Merge pull request #2735 from jareckib/master

[RRG-proxmark3.git] / common / mbedtls / psa_crypto.c

/*
 *  PSA crypto layer on top of Mbed TLS crypto
 */
/*
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#include "common.h"

#if defined(MBEDTLS_PSA_CRYPTO_C)

#if defined(MBEDTLS_PSA_CRYPTO_CONFIG)
#include "check_crypto_config.h"
#endif

#include "psa_crypto_service_integration.h"
#include "psa/crypto.h"

#include "psa_crypto_core.h"
#include "psa_crypto_invasive.h"
#include "psa_crypto_driver_wrappers.h"
#include "psa_crypto_ecp.h"
#include "psa_crypto_rsa.h"
#include "psa_crypto_ecp.h"
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
#include "psa_crypto_se.h"
#endif
#include "psa_crypto_slot_management.h"
/* Include internal declarations that are useful for implementing persistently
 * stored keys. */
#include "psa_crypto_storage.h"

#include "psa_crypto_random_impl.h"

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "mbedtls/platform.h"
#if !defined(MBEDTLS_PLATFORM_C)
#define mbedtls_calloc calloc
#define mbedtls_free   free
#endif

#include "mbedtls/aes.h"
#include "mbedtls/arc4.h"
#include "mbedtls/asn1.h"
#include "mbedtls/asn1write.h"
#include "mbedtls/bignum.h"
#include "mbedtls/blowfish.h"
#include "mbedtls/camellia.h"
#include "mbedtls/chacha20.h"
#include "mbedtls/chachapoly.h"
#include "mbedtls/cipher.h"
#include "mbedtls/ccm.h"
#include "mbedtls/cmac.h"
#include "mbedtls/des.h"
#include "mbedtls/ecdh.h"
#include "mbedtls/ecp.h"
#include "mbedtls/entropy.h"
#include "mbedtls/error.h"
#include "mbedtls/gcm.h"
#include "mbedtls/md2.h"
#include "mbedtls/md4.h"
#include "mbedtls/md5.h"
#include "mbedtls/md.h"
#include "mbedtls/md_internal.h"
#include "mbedtls/pk.h"
#include "mbedtls/pk_internal.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include "mbedtls/ripemd160.h"
#include "mbedtls/rsa.h"
#include "mbedtls/sha1.h"
#include "mbedtls/sha256.h"
#include "mbedtls/sha512.h"
#include "mbedtls/xtea.h"

#define ARRAY_LENGTH( array ) ( sizeof( array ) / sizeof( *( array ) ) )

/* constant-time buffer comparison */
static inline int safer_memcmp(const uint8_t *a, const uint8_t *b, size_t n) {
    size_t i;
    unsigned char diff = 0;

    for (i = 0; i < n; i++)
        diff |= a[i] ^ b[i];

    return (diff);
}



/****************************************************************/
/* Global data, support functions and library management */
/****************************************************************/

static int key_type_is_raw_bytes(psa_key_type_t type) {
    return (PSA_KEY_TYPE_IS_UNSTRUCTURED(type));
}

/* Values for psa_global_data_t::rng_state */
#define RNG_NOT_INITIALIZED 0
#define RNG_INITIALIZED 1
#define RNG_SEEDED 2

typedef struct {
    mbedtls_psa_random_context_t rng;
    unsigned initialized : 1;
    unsigned rng_state : 2;
} psa_global_data_t;

static psa_global_data_t global_data;

#if !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
mbedtls_psa_drbg_context_t *const mbedtls_psa_random_state =
    &global_data.rng.drbg;
#endif

#define GUARD_MODULE_INITIALIZED        \
    if( global_data.initialized == 0 )  \
        return( PSA_ERROR_BAD_STATE );

psa_status_t mbedtls_to_psa_error(int ret) {
    /* Mbed TLS error codes can combine a high-level error code and a
     * low-level error code. The low-level error usually reflects the
     * root cause better, so dispatch on that preferably. */
    int low_level_ret = - (-ret & 0x007f);
    switch (low_level_ret != 0 ? low_level_ret : ret) {
        case 0:
            return (PSA_SUCCESS);

        case MBEDTLS_ERR_AES_INVALID_KEY_LENGTH:
        case MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH:
        case MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_AES_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_ARC4_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_ASN1_OUT_OF_DATA:
        case MBEDTLS_ERR_ASN1_UNEXPECTED_TAG:
        case MBEDTLS_ERR_ASN1_INVALID_LENGTH:
        case MBEDTLS_ERR_ASN1_LENGTH_MISMATCH:
        case MBEDTLS_ERR_ASN1_INVALID_DATA:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_ASN1_ALLOC_FAILED:
            return (PSA_ERROR_INSUFFICIENT_MEMORY);
        case MBEDTLS_ERR_ASN1_BUF_TOO_SMALL:
            return (PSA_ERROR_BUFFER_TOO_SMALL);

#if defined(MBEDTLS_ERR_BLOWFISH_BAD_INPUT_DATA)
        case MBEDTLS_ERR_BLOWFISH_BAD_INPUT_DATA:
#elif defined(MBEDTLS_ERR_BLOWFISH_INVALID_KEY_LENGTH)
        case MBEDTLS_ERR_BLOWFISH_INVALID_KEY_LENGTH:
#endif
        case MBEDTLS_ERR_BLOWFISH_INVALID_INPUT_LENGTH:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_BLOWFISH_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

#if defined(MBEDTLS_ERR_CAMELLIA_BAD_INPUT_DATA)
        case MBEDTLS_ERR_CAMELLIA_BAD_INPUT_DATA:
#elif defined(MBEDTLS_ERR_CAMELLIA_INVALID_KEY_LENGTH)
        case MBEDTLS_ERR_CAMELLIA_INVALID_KEY_LENGTH:
#endif
        case MBEDTLS_ERR_CAMELLIA_INVALID_INPUT_LENGTH:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_CAMELLIA_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_CCM_BAD_INPUT:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_CCM_AUTH_FAILED:
            return (PSA_ERROR_INVALID_SIGNATURE);
        case MBEDTLS_ERR_CCM_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA:
            return (PSA_ERROR_INVALID_ARGUMENT);

        case MBEDTLS_ERR_CHACHAPOLY_BAD_STATE:
            return (PSA_ERROR_BAD_STATE);
        case MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED:
            return (PSA_ERROR_INVALID_SIGNATURE);

        case MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_CIPHER_ALLOC_FAILED:
            return (PSA_ERROR_INSUFFICIENT_MEMORY);
        case MBEDTLS_ERR_CIPHER_INVALID_PADDING:
            return (PSA_ERROR_INVALID_PADDING);
        case MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_CIPHER_AUTH_FAILED:
            return (PSA_ERROR_INVALID_SIGNATURE);
        case MBEDTLS_ERR_CIPHER_INVALID_CONTEXT:
            return (PSA_ERROR_CORRUPTION_DETECTED);
        case MBEDTLS_ERR_CIPHER_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_CMAC_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

#if !( defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) ||      \
       defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE) )
        /* Only check CTR_DRBG error codes if underlying mbedtls_xxx
         * functions are passed a CTR_DRBG instance. */
        case MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED:
            return (PSA_ERROR_INSUFFICIENT_ENTROPY);
        case MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG:
        case MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR:
            return (PSA_ERROR_INSUFFICIENT_ENTROPY);
#endif

        case MBEDTLS_ERR_DES_INVALID_INPUT_LENGTH:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_DES_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED:
        case MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE:
        case MBEDTLS_ERR_ENTROPY_SOURCE_FAILED:
            return (PSA_ERROR_INSUFFICIENT_ENTROPY);

        case MBEDTLS_ERR_GCM_AUTH_FAILED:
            return (PSA_ERROR_INVALID_SIGNATURE);
        case MBEDTLS_ERR_GCM_BAD_INPUT:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_GCM_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

#if !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) &&        \
    defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE)
        /* Only check HMAC_DRBG error codes if underlying mbedtls_xxx
         * functions are passed a HMAC_DRBG instance. */
        case MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED:
            return (PSA_ERROR_INSUFFICIENT_ENTROPY);
        case MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG:
        case MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR:
            return (PSA_ERROR_INSUFFICIENT_ENTROPY);
#endif

        case MBEDTLS_ERR_MD2_HW_ACCEL_FAILED:
        case MBEDTLS_ERR_MD4_HW_ACCEL_FAILED:
        case MBEDTLS_ERR_MD5_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_MD_BAD_INPUT_DATA:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_MD_ALLOC_FAILED:
            return (PSA_ERROR_INSUFFICIENT_MEMORY);
        case MBEDTLS_ERR_MD_FILE_IO_ERROR:
            return (PSA_ERROR_STORAGE_FAILURE);
        case MBEDTLS_ERR_MD_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_MPI_FILE_IO_ERROR:
            return (PSA_ERROR_STORAGE_FAILURE);
        case MBEDTLS_ERR_MPI_BAD_INPUT_DATA:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_MPI_INVALID_CHARACTER:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL:
            return (PSA_ERROR_BUFFER_TOO_SMALL);
        case MBEDTLS_ERR_MPI_NEGATIVE_VALUE:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_MPI_DIVISION_BY_ZERO:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_MPI_NOT_ACCEPTABLE:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_MPI_ALLOC_FAILED:
            return (PSA_ERROR_INSUFFICIENT_MEMORY);

        case MBEDTLS_ERR_PK_ALLOC_FAILED:
            return (PSA_ERROR_INSUFFICIENT_MEMORY);
        case MBEDTLS_ERR_PK_TYPE_MISMATCH:
        case MBEDTLS_ERR_PK_BAD_INPUT_DATA:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_PK_FILE_IO_ERROR:
            return (PSA_ERROR_STORAGE_FAILURE);
        case MBEDTLS_ERR_PK_KEY_INVALID_VERSION:
        case MBEDTLS_ERR_PK_KEY_INVALID_FORMAT:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_PK_UNKNOWN_PK_ALG:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_PK_PASSWORD_REQUIRED:
        case MBEDTLS_ERR_PK_PASSWORD_MISMATCH:
            return (PSA_ERROR_NOT_PERMITTED);
        case MBEDTLS_ERR_PK_INVALID_PUBKEY:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_PK_INVALID_ALG:
        case MBEDTLS_ERR_PK_UNKNOWN_NAMED_CURVE:
        case MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_PK_SIG_LEN_MISMATCH:
            return (PSA_ERROR_INVALID_SIGNATURE);
        case MBEDTLS_ERR_PK_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);
        case MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED:
            return (PSA_ERROR_NOT_SUPPORTED);

        case MBEDTLS_ERR_RIPEMD160_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_RSA_BAD_INPUT_DATA:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_RSA_INVALID_PADDING:
            return (PSA_ERROR_INVALID_PADDING);
        case MBEDTLS_ERR_RSA_KEY_GEN_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);
        case MBEDTLS_ERR_RSA_KEY_CHECK_FAILED:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_RSA_PUBLIC_FAILED:
        case MBEDTLS_ERR_RSA_PRIVATE_FAILED:
            return (PSA_ERROR_CORRUPTION_DETECTED);
        case MBEDTLS_ERR_RSA_VERIFY_FAILED:
            return (PSA_ERROR_INVALID_SIGNATURE);
        case MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE:
            return (PSA_ERROR_BUFFER_TOO_SMALL);
        case MBEDTLS_ERR_RSA_RNG_FAILED:
            return (PSA_ERROR_INSUFFICIENT_ENTROPY);
        case MBEDTLS_ERR_RSA_UNSUPPORTED_OPERATION:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_RSA_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_SHA1_HW_ACCEL_FAILED:
        case MBEDTLS_ERR_SHA256_HW_ACCEL_FAILED:
        case MBEDTLS_ERR_SHA512_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_XTEA_INVALID_INPUT_LENGTH:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_XTEA_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_ECP_BAD_INPUT_DATA:
        case MBEDTLS_ERR_ECP_INVALID_KEY:
            return (PSA_ERROR_INVALID_ARGUMENT);
        case MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL:
            return (PSA_ERROR_BUFFER_TOO_SMALL);
        case MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE:
            return (PSA_ERROR_NOT_SUPPORTED);
        case MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH:
        case MBEDTLS_ERR_ECP_VERIFY_FAILED:
            return (PSA_ERROR_INVALID_SIGNATURE);
        case MBEDTLS_ERR_ECP_ALLOC_FAILED:
            return (PSA_ERROR_INSUFFICIENT_MEMORY);
        case MBEDTLS_ERR_ECP_RANDOM_FAILED:
            return (PSA_ERROR_INSUFFICIENT_ENTROPY);
        case MBEDTLS_ERR_ECP_HW_ACCEL_FAILED:
            return (PSA_ERROR_HARDWARE_FAILURE);

        case MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED:
            return (PSA_ERROR_CORRUPTION_DETECTED);

        default:
            return (PSA_ERROR_GENERIC_ERROR);
    }
}




/****************************************************************/
/* Key management */
/****************************************************************/

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
static inline int psa_key_slot_is_external(const psa_key_slot_t *slot) {
    return (psa_key_lifetime_is_external(slot->attr.lifetime));
}
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

/* For now the MBEDTLS_PSA_ACCEL_ guards are also used here since the
 * current test driver in key_management.c is using this function
 * when accelerators are used for ECC key pair and public key.
 * Once that dependency is resolved these guards can be removed.
 */
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) || \
    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY) || \
    defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_KEY_PAIR) || \
    defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_PUBLIC_KEY)
mbedtls_ecp_group_id mbedtls_ecc_group_of_psa(psa_ecc_family_t curve,
                                              size_t bits,
                                              int bits_is_sloppy) {
    switch (curve) {
        case PSA_ECC_FAMILY_SECP_R1:
            switch (bits) {
                case 192:
                    return (MBEDTLS_ECP_DP_SECP192R1);
                case 224:
                    return (MBEDTLS_ECP_DP_SECP224R1);
                case 256:
                    return (MBEDTLS_ECP_DP_SECP256R1);
                case 384:
                    return (MBEDTLS_ECP_DP_SECP384R1);
                case 521:
                    return (MBEDTLS_ECP_DP_SECP521R1);
                case 528:
                    if (bits_is_sloppy)
                        return (MBEDTLS_ECP_DP_SECP521R1);
                    break;
            }
            break;

        case PSA_ECC_FAMILY_BRAINPOOL_P_R1:
            switch (bits) {
                case 256:
                    return (MBEDTLS_ECP_DP_BP256R1);
                case 384:
                    return (MBEDTLS_ECP_DP_BP384R1);
                case 512:
                    return (MBEDTLS_ECP_DP_BP512R1);
            }
            break;

        case PSA_ECC_FAMILY_MONTGOMERY:
            switch (bits) {
                case 255:
                    return (MBEDTLS_ECP_DP_CURVE25519);
                case 256:
                    if (bits_is_sloppy)
                        return (MBEDTLS_ECP_DP_CURVE25519);
                    break;
                case 448:
                    return (MBEDTLS_ECP_DP_CURVE448);
            }
            break;

        case PSA_ECC_FAMILY_SECP_K1:
            switch (bits) {
                case 192:
                    return (MBEDTLS_ECP_DP_SECP192K1);
                case 224:
                    return (MBEDTLS_ECP_DP_SECP224K1);
                case 256:
                    return (MBEDTLS_ECP_DP_SECP256K1);
            }
            break;
    }

    return (MBEDTLS_ECP_DP_NONE);
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) ||
        * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY) ||
        * defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_KEY_PAIR) ||
        * defined(MBEDTLS_PSA_ACCEL_KEY_TYPE_ECC_PUBLIC_KEY) */

static psa_status_t validate_unstructured_key_bit_size(psa_key_type_t type,
                                                       size_t bits) {
    /* Check that the bit size is acceptable for the key type */
    switch (type) {
        case PSA_KEY_TYPE_RAW_DATA:
        case PSA_KEY_TYPE_HMAC:
        case PSA_KEY_TYPE_DERIVE:
            break;
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_AES)
        case PSA_KEY_TYPE_AES:
            if (bits != 128 && bits != 192 && bits != 256)
                return (PSA_ERROR_INVALID_ARGUMENT);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_CAMELLIA)
        case PSA_KEY_TYPE_CAMELLIA:
            if (bits != 128 && bits != 192 && bits != 256)
                return (PSA_ERROR_INVALID_ARGUMENT);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES)
        case PSA_KEY_TYPE_DES:
            if (bits != 64 && bits != 128 && bits != 192)
                return (PSA_ERROR_INVALID_ARGUMENT);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ARC4)
        case PSA_KEY_TYPE_ARC4:
            if (bits < 8 || bits > 2048)
                return (PSA_ERROR_INVALID_ARGUMENT);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_CHACHA20)
        case PSA_KEY_TYPE_CHACHA20:
            if (bits != 256)
                return (PSA_ERROR_INVALID_ARGUMENT);
            break;
#endif
        default:
            return (PSA_ERROR_NOT_SUPPORTED);
    }
    if (bits % 8 != 0)
        return (PSA_ERROR_INVALID_ARGUMENT);

    return (PSA_SUCCESS);
}

/** Return the size of the key in the given slot, in bits.
 *
 * \param[in] slot      A key slot.
 *
 * \return The key size in bits, read from the metadata in the slot.
 */
static inline size_t psa_get_key_slot_bits(const psa_key_slot_t *slot) {
    return (slot->attr.bits);
}

/** Check whether a given key type is valid for use with a given MAC algorithm
 *
 * Upon successful return of this function, the behavior of #PSA_MAC_LENGTH
 * when called with the validated \p algorithm and \p key_type is well-defined.
 *
 * \param[in] algorithm     The specific MAC algorithm (can be wildcard).
 * \param[in] key_type      The key type of the key to be used with the
 *                          \p algorithm.
 *
 * \retval #PSA_SUCCESS
 *         The \p key_type is valid for use with the \p algorithm
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The \p key_type is not valid for use with the \p algorithm
 */
MBEDTLS_STATIC_TESTABLE psa_status_t psa_mac_key_can_do(
    psa_algorithm_t algorithm,
    psa_key_type_t key_type) {
    if (PSA_ALG_IS_HMAC(algorithm)) {
        if (key_type == PSA_KEY_TYPE_HMAC)
            return (PSA_SUCCESS);
    }

    if (PSA_ALG_IS_BLOCK_CIPHER_MAC(algorithm)) {
        /* Check that we're calling PSA_BLOCK_CIPHER_BLOCK_LENGTH with a cipher
         * key. */
        if ((key_type & PSA_KEY_TYPE_CATEGORY_MASK) ==
                PSA_KEY_TYPE_CATEGORY_SYMMETRIC) {
            /* PSA_BLOCK_CIPHER_BLOCK_LENGTH returns 1 for stream ciphers and
             * the block length (larger than 1) for block ciphers. */
            if (PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type) > 1)
                return (PSA_SUCCESS);
        }
    }

    return (PSA_ERROR_INVALID_ARGUMENT);
}

/** Try to allocate a buffer to an empty key slot.
 *
 * \param[in,out] slot          Key slot to attach buffer to.
 * \param[in] buffer_length     Requested size of the buffer.
 *
 * \retval #PSA_SUCCESS
 *         The buffer has been successfully allocated.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 *         Not enough memory was available for allocation.
 * \retval #PSA_ERROR_ALREADY_EXISTS
 *         Trying to allocate a buffer to a non-empty key slot.
 */
static psa_status_t psa_allocate_buffer_to_slot(psa_key_slot_t *slot,
                                                size_t buffer_length) {
    if (slot->key.data != NULL)
        return (PSA_ERROR_ALREADY_EXISTS);

    slot->key.data = mbedtls_calloc(1, buffer_length);
    if (slot->key.data == NULL)
        return (PSA_ERROR_INSUFFICIENT_MEMORY);

    slot->key.bytes = buffer_length;
    return (PSA_SUCCESS);
}

psa_status_t psa_copy_key_material_into_slot(psa_key_slot_t *slot,
                                             const uint8_t *data,
                                             size_t data_length) {
    psa_status_t status = psa_allocate_buffer_to_slot(slot,
                                                      data_length);
    if (status != PSA_SUCCESS)
        return (status);

    memcpy(slot->key.data, data, data_length);
    return (PSA_SUCCESS);
}

psa_status_t psa_import_key_into_slot(
    const psa_key_attributes_t *attributes,
    const uint8_t *data, size_t data_length,
    uint8_t *key_buffer, size_t key_buffer_size,
    size_t *key_buffer_length, size_t *bits) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_type_t type = attributes->core.type;

    /* zero-length keys are never supported. */
    if (data_length == 0)
        return (PSA_ERROR_NOT_SUPPORTED);

    if (key_type_is_raw_bytes(type)) {
        *bits = PSA_BYTES_TO_BITS(data_length);

        /* Ensure that the bytes-to-bits conversion hasn't overflown. */
        if (data_length > SIZE_MAX / 8)
            return (PSA_ERROR_NOT_SUPPORTED);

        /* Enforce a size limit, and in particular ensure that the bit
         * size fits in its representation type. */
        if ((*bits) > PSA_MAX_KEY_BITS)
            return (PSA_ERROR_NOT_SUPPORTED);

        status = validate_unstructured_key_bit_size(type, *bits);
        if (status != PSA_SUCCESS)
            return (status);

        /* Copy the key material. */
        memcpy(key_buffer, data, data_length);
        *key_buffer_length = data_length;
        (void)key_buffer_size;

        return (PSA_SUCCESS);
    } else if (PSA_KEY_TYPE_IS_ASYMMETRIC(type)) {
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) || \
    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY)
        if (PSA_KEY_TYPE_IS_ECC(type)) {
            return (mbedtls_psa_ecp_import_key(attributes,
                                               data, data_length,
                                               key_buffer, key_buffer_size,
                                               key_buffer_length,
                                               bits));
        }
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) ||
        * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY) */
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) || \
    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY)
        if (PSA_KEY_TYPE_IS_RSA(type)) {
            return (mbedtls_psa_rsa_import_key(attributes,
                                               data, data_length,
                                               key_buffer, key_buffer_size,
                                               key_buffer_length,
                                               bits));
        }
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) ||
        * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY) */
    }

    return (PSA_ERROR_NOT_SUPPORTED);
}

/** Calculate the intersection of two algorithm usage policies.
 *
 * Return 0 (which allows no operation) on incompatibility.
 */
static psa_algorithm_t psa_key_policy_algorithm_intersection(
    psa_key_type_t key_type,
    psa_algorithm_t alg1,
    psa_algorithm_t alg2) {
    /* Common case: both sides actually specify the same policy. */
    if (alg1 == alg2)
        return (alg1);
    /* If the policies are from the same hash-and-sign family, check
     * if one is a wildcard. If so the other has the specific algorithm. */
    if (PSA_ALG_IS_HASH_AND_SIGN(alg1) &&
            PSA_ALG_IS_HASH_AND_SIGN(alg2) &&
            (alg1 & ~PSA_ALG_HASH_MASK) == (alg2 & ~PSA_ALG_HASH_MASK)) {
        if (PSA_ALG_SIGN_GET_HASH(alg1) == PSA_ALG_ANY_HASH)
            return (alg2);
        if (PSA_ALG_SIGN_GET_HASH(alg2) == PSA_ALG_ANY_HASH)
            return (alg1);
    }
    /* If the policies are from the same AEAD family, check whether
     * one of them is a minimum-tag-length wildcard. Calculate the most
     * restrictive tag length. */
    if (PSA_ALG_IS_AEAD(alg1) && PSA_ALG_IS_AEAD(alg2) &&
            (PSA_ALG_AEAD_WITH_SHORTENED_TAG(alg1, 0) ==
             PSA_ALG_AEAD_WITH_SHORTENED_TAG(alg2, 0))) {
        size_t alg1_len = PSA_ALG_AEAD_GET_TAG_LENGTH(alg1);
        size_t alg2_len = PSA_ALG_AEAD_GET_TAG_LENGTH(alg2);
        size_t restricted_len = alg1_len > alg2_len ? alg1_len : alg2_len;

        /* If both are wildcards, return most restrictive wildcard */
        if (((alg1 & PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG) != 0) &&
                ((alg2 & PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG) != 0)) {
            return (PSA_ALG_AEAD_WITH_AT_LEAST_THIS_LENGTH_TAG(
                        alg1, restricted_len));
        }
        /* If only one is a wildcard, return specific algorithm if compatible. */
        if (((alg1 & PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG) != 0) &&
                (alg1_len <= alg2_len)) {
            return (alg2);
        }
        if (((alg2 & PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG) != 0) &&
                (alg2_len <= alg1_len)) {
            return (alg1);
        }
    }
    /* If the policies are from the same MAC family, check whether one
     * of them is a minimum-MAC-length policy. Calculate the most
     * restrictive tag length. */
    if (PSA_ALG_IS_MAC(alg1) && PSA_ALG_IS_MAC(alg2) &&
            (PSA_ALG_FULL_LENGTH_MAC(alg1) ==
             PSA_ALG_FULL_LENGTH_MAC(alg2))) {
        /* Validate the combination of key type and algorithm. Since the base
         * algorithm of alg1 and alg2 are the same, we only need this once. */
        if (PSA_SUCCESS != psa_mac_key_can_do(alg1, key_type))
            return (0);

        /* Get the (exact or at-least) output lengths for both sides of the
         * requested intersection. None of the currently supported algorithms
         * have an output length dependent on the actual key size, so setting it
         * to a bogus value of 0 is currently OK.
         *
         * Note that for at-least-this-length wildcard algorithms, the output
         * length is set to the shortest allowed length, which allows us to
         * calculate the most restrictive tag length for the intersection. */
        size_t alg1_len = PSA_MAC_LENGTH(key_type, 0, alg1);
        size_t alg2_len = PSA_MAC_LENGTH(key_type, 0, alg2);
        size_t restricted_len = alg1_len > alg2_len ? alg1_len : alg2_len;

        /* If both are wildcards, return most restrictive wildcard */
        if (((alg1 & PSA_ALG_MAC_AT_LEAST_THIS_LENGTH_FLAG) != 0) &&
                ((alg2 & PSA_ALG_MAC_AT_LEAST_THIS_LENGTH_FLAG) != 0)) {
            return (PSA_ALG_AT_LEAST_THIS_LENGTH_MAC(alg1, restricted_len));
        }

        /* If only one is an at-least-this-length policy, the intersection would
         * be the other (fixed-length) policy as long as said fixed length is
         * equal to or larger than the shortest allowed length. */
        if ((alg1 & PSA_ALG_MAC_AT_LEAST_THIS_LENGTH_FLAG) != 0) {
            return ((alg1_len <= alg2_len) ? alg2 : 0);
        }
        if ((alg2 & PSA_ALG_MAC_AT_LEAST_THIS_LENGTH_FLAG) != 0) {
            return ((alg2_len <= alg1_len) ? alg1 : 0);
        }

        /* If none of them are wildcards, check whether they define the same tag
         * length. This is still possible here when one is default-length and
         * the other specific-length. Ensure to always return the
         * specific-length version for the intersection. */
        if (alg1_len == alg2_len)
            return (PSA_ALG_TRUNCATED_MAC(alg1, alg1_len));
    }
    /* If the policies are incompatible, allow nothing. */
    return (0);
}

static int psa_key_algorithm_permits(psa_key_type_t key_type,
                                     psa_algorithm_t policy_alg,
                                     psa_algorithm_t requested_alg) {
    /* Common case: the policy only allows requested_alg. */
    if (requested_alg == policy_alg)
        return (1);
    /* If policy_alg is a hash-and-sign with a wildcard for the hash,
     * and requested_alg is the same hash-and-sign family with any hash,
     * then requested_alg is compliant with policy_alg. */
    if (PSA_ALG_IS_HASH_AND_SIGN(requested_alg) &&
            PSA_ALG_SIGN_GET_HASH(policy_alg) == PSA_ALG_ANY_HASH) {
        return ((policy_alg & ~PSA_ALG_HASH_MASK) ==
                (requested_alg & ~PSA_ALG_HASH_MASK));
    }
    /* If policy_alg is a wildcard AEAD algorithm of the same base as
     * the requested algorithm, check the requested tag length to be
     * equal-length or longer than the wildcard-specified length. */
    if (PSA_ALG_IS_AEAD(policy_alg) &&
            PSA_ALG_IS_AEAD(requested_alg) &&
            (PSA_ALG_AEAD_WITH_SHORTENED_TAG(policy_alg, 0) ==
             PSA_ALG_AEAD_WITH_SHORTENED_TAG(requested_alg, 0)) &&
            ((policy_alg & PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG) != 0)) {
        return (PSA_ALG_AEAD_GET_TAG_LENGTH(policy_alg) <=
                PSA_ALG_AEAD_GET_TAG_LENGTH(requested_alg));
    }
    /* If policy_alg is a MAC algorithm of the same base as the requested
     * algorithm, check whether their MAC lengths are compatible. */
    if (PSA_ALG_IS_MAC(policy_alg) &&
            PSA_ALG_IS_MAC(requested_alg) &&
            (PSA_ALG_FULL_LENGTH_MAC(policy_alg) ==
             PSA_ALG_FULL_LENGTH_MAC(requested_alg))) {
        /* Validate the combination of key type and algorithm. Since the policy
         * and requested algorithms are the same, we only need this once. */
        if (PSA_SUCCESS != psa_mac_key_can_do(policy_alg, key_type))
            return (0);

        /* Get both the requested output length for the algorithm which is to be
         * verified, and the default output length for the base algorithm.
         * Note that none of the currently supported algorithms have an output
         * length dependent on actual key size, so setting it to a bogus value
         * of 0 is currently OK. */
        size_t requested_output_length = PSA_MAC_LENGTH(
                                             key_type, 0, requested_alg);
        size_t default_output_length = PSA_MAC_LENGTH(
                                           key_type, 0,
                                           PSA_ALG_FULL_LENGTH_MAC(requested_alg));

        /* If the policy is default-length, only allow an algorithm with
         * a declared exact-length matching the default. */
        if (PSA_MAC_TRUNCATED_LENGTH(policy_alg) == 0)
            return (requested_output_length == default_output_length);

        /* If the requested algorithm is default-length, allow it if the policy
         * length exactly matches the default length. */
        if (PSA_MAC_TRUNCATED_LENGTH(requested_alg) == 0 &&
                PSA_MAC_TRUNCATED_LENGTH(policy_alg) == default_output_length) {
            return (1);
        }

        /* If policy_alg is an at-least-this-length wildcard MAC algorithm,
         * check for the requested MAC length to be equal to or longer than the
         * minimum allowed length. */
        if ((policy_alg & PSA_ALG_MAC_AT_LEAST_THIS_LENGTH_FLAG) != 0) {
            return (PSA_MAC_TRUNCATED_LENGTH(policy_alg) <=
                    requested_output_length);
        }
    }
    /* If policy_alg is a generic key agreement operation, then using it for
     * a key derivation with that key agreement should also be allowed. This
     * behaviour is expected to be defined in a future specification version. */
    if (PSA_ALG_IS_RAW_KEY_AGREEMENT(policy_alg) &&
            PSA_ALG_IS_KEY_AGREEMENT(requested_alg)) {
        return (PSA_ALG_KEY_AGREEMENT_GET_BASE(requested_alg) ==
                policy_alg);
    }
    /* If it isn't explicitly permitted, it's forbidden. */
    return (0);
}

/** Test whether a policy permits an algorithm.
 *
 * The caller must test usage flags separately.
 *
 * \note This function requires providing the key type for which the policy is
 *       being validated, since some algorithm policy definitions (e.g. MAC)
 *       have different properties depending on what kind of cipher it is
 *       combined with.
 *
 * \retval PSA_SUCCESS                  When \p alg is a specific algorithm
 *                                      allowed by the \p policy.
 * \retval PSA_ERROR_INVALID_ARGUMENT   When \p alg is not a specific algorithm
 * \retval PSA_ERROR_NOT_PERMITTED      When \p alg is a specific algorithm, but
 *                                      the \p policy does not allow it.
 */
static psa_status_t psa_key_policy_permits(const psa_key_policy_t *policy,
                                           psa_key_type_t key_type,
                                           psa_algorithm_t alg) {
    /* '0' is not a valid algorithm */
    if (alg == 0)
        return (PSA_ERROR_INVALID_ARGUMENT);

    /* A requested algorithm cannot be a wildcard. */
    if (PSA_ALG_IS_WILDCARD(alg))
        return (PSA_ERROR_INVALID_ARGUMENT);

    if (psa_key_algorithm_permits(key_type, policy->alg, alg) ||
            psa_key_algorithm_permits(key_type, policy->alg2, alg))
        return (PSA_SUCCESS);
    else
        return (PSA_ERROR_NOT_PERMITTED);
}

/** Restrict a key policy based on a constraint.
 *
 * \note This function requires providing the key type for which the policy is
 *       being restricted, since some algorithm policy definitions (e.g. MAC)
 *       have different properties depending on what kind of cipher it is
 *       combined with.
 *
 * \param[in] key_type      The key type for which to restrict the policy
 * \param[in,out] policy    The policy to restrict.
 * \param[in] constraint    The policy constraint to apply.
 *
 * \retval #PSA_SUCCESS
 *         \c *policy contains the intersection of the original value of
 *         \c *policy and \c *constraint.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         \c key_type, \c *policy and \c *constraint are incompatible.
 *         \c *policy is unchanged.
 */
static psa_status_t psa_restrict_key_policy(
    psa_key_type_t key_type,
    psa_key_policy_t *policy,
    const psa_key_policy_t *constraint) {
    psa_algorithm_t intersection_alg =
        psa_key_policy_algorithm_intersection(key_type, policy->alg,
                                              constraint->alg);
    psa_algorithm_t intersection_alg2 =
        psa_key_policy_algorithm_intersection(key_type, policy->alg2,
                                              constraint->alg2);
    if (intersection_alg == 0 && policy->alg != 0 && constraint->alg != 0)
        return (PSA_ERROR_INVALID_ARGUMENT);
    if (intersection_alg2 == 0 && policy->alg2 != 0 && constraint->alg2 != 0)
        return (PSA_ERROR_INVALID_ARGUMENT);
    policy->usage &= constraint->usage;
    policy->alg = intersection_alg;
    policy->alg2 = intersection_alg2;
    return (PSA_SUCCESS);
}

/** Get the description of a key given its identifier and policy constraints
 *  and lock it.
 *
 * The key must have allow all the usage flags set in \p usage. If \p alg is
 * nonzero, the key must allow operations with this algorithm. If \p alg is
 * zero, the algorithm is not checked.
 *
 * In case of a persistent key, the function loads the description of the key
 * into a key slot if not already done.
 *
 * On success, the returned key slot is locked. It is the responsibility of
 * the caller to unlock the key slot when it does not access it anymore.
 */
static psa_status_t psa_get_and_lock_key_slot_with_policy(
    mbedtls_svc_key_id_t key,
    psa_key_slot_t **p_slot,
    psa_key_usage_t usage,
    psa_algorithm_t alg) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    status = psa_get_and_lock_key_slot(key, p_slot);
    if (status != PSA_SUCCESS)
        return (status);
    slot = *p_slot;

    /* Enforce that usage policy for the key slot contains all the flags
     * required by the usage parameter. There is one exception: public
     * keys can always be exported, so we treat public key objects as
     * if they had the export flag. */
    if (PSA_KEY_TYPE_IS_PUBLIC_KEY(slot->attr.type))
        usage &= ~PSA_KEY_USAGE_EXPORT;

    if ((slot->attr.policy.usage & usage) != usage) {
        status = PSA_ERROR_NOT_PERMITTED;
        goto error;
    }

    /* Enforce that the usage policy permits the requested algortihm. */
    if (alg != 0) {
        status = psa_key_policy_permits(&slot->attr.policy,
                                        slot->attr.type,
                                        alg);
        if (status != PSA_SUCCESS)
            goto error;
    }

    return (PSA_SUCCESS);

error:
    *p_slot = NULL;
    psa_unlock_key_slot(slot);

    return (status);
}

/** Get a key slot containing a transparent key and lock it.
 *
 * A transparent key is a key for which the key material is directly
 * available, as opposed to a key in a secure element.
 *
 * This is a temporary function to use instead of
 * psa_get_and_lock_key_slot_with_policy() until secure element support is
 * fully implemented.
 *
 * On success, the returned key slot is locked. It is the responsibility of the
 * caller to unlock the key slot when it does not access it anymore.
 */
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
static psa_status_t psa_get_and_lock_transparent_key_slot_with_policy(
    mbedtls_svc_key_id_t key,
    psa_key_slot_t **p_slot,
    psa_key_usage_t usage,
    psa_algorithm_t alg) {
    psa_status_t status = psa_get_and_lock_key_slot_with_policy(key, p_slot,
                                                                usage, alg);
    if (status != PSA_SUCCESS)
        return (status);

    if (psa_key_slot_is_external(*p_slot)) {
        psa_unlock_key_slot(*p_slot);
        *p_slot = NULL;
        return (PSA_ERROR_NOT_SUPPORTED);
    }

    return (PSA_SUCCESS);
}
#else /* MBEDTLS_PSA_CRYPTO_SE_C */
/* With no secure element support, all keys are transparent. */
#define psa_get_and_lock_transparent_key_slot_with_policy( key, p_slot, usage, alg )   \
    psa_get_and_lock_key_slot_with_policy( key, p_slot, usage, alg )
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

/** Wipe key data from a slot. Preserve metadata such as the policy. */
static psa_status_t psa_remove_key_data_from_memory(psa_key_slot_t *slot) {
    /* Data pointer will always be either a valid pointer or NULL in an
     * initialized slot, so we can just free it. */
    if (slot->key.data != NULL)
        mbedtls_platform_zeroize(slot->key.data, slot->key.bytes);

    mbedtls_free(slot->key.data);
    slot->key.data = NULL;
    slot->key.bytes = 0;

    return (PSA_SUCCESS);
}

/** Completely wipe a slot in memory, including its policy.
 * Persistent storage is not affected. */
psa_status_t psa_wipe_key_slot(psa_key_slot_t *slot) {
    psa_status_t status = psa_remove_key_data_from_memory(slot);

    /*
     * As the return error code may not be handled in case of multiple errors,
     * do our best to report an unexpected lock counter: if available
     * call MBEDTLS_PARAM_FAILED that may terminate execution (if called as
     * part of the execution of a test suite this will stop the test suite
     * execution).
     */
    if (slot->lock_count != 1) {
#ifdef MBEDTLS_CHECK_PARAMS
        MBEDTLS_PARAM_FAILED(slot->lock_count == 1);
#endif
        status = PSA_ERROR_CORRUPTION_DETECTED;
    }

    /* Multipart operations may still be using the key. This is safe
     * because all multipart operation objects are independent from
     * the key slot: if they need to access the key after the setup
     * phase, they have a copy of the key. Note that this means that
     * key material can linger until all operations are completed. */
    /* At this point, key material and other type-specific content has
     * been wiped. Clear remaining metadata. We can call memset and not
     * zeroize because the metadata is not particularly sensitive. */
    memset(slot, 0, sizeof(*slot));
    return (status);
}

psa_status_t psa_destroy_key(mbedtls_svc_key_id_t key) {
    psa_key_slot_t *slot;
    psa_status_t status; /* status of the last operation */
    psa_status_t overall_status = PSA_SUCCESS;
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    psa_se_drv_table_entry_t *driver;
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

    if (mbedtls_svc_key_id_is_null(key))
        return (PSA_SUCCESS);

    /*
     * Get the description of the key in a key slot. In case of a persistent
     * key, this will load the key description from persistent memory if not
     * done yet. We cannot avoid this loading as without it we don't know if
     * the key is operated by an SE or not and this information is needed by
     * the current implementation.
     */
    status = psa_get_and_lock_key_slot(key, &slot);
    if (status != PSA_SUCCESS)
        return (status);

    /*
     * If the key slot containing the key description is under access by the
     * library (apart from the present access), the key cannot be destroyed
     * yet. For the time being, just return in error. Eventually (to be
     * implemented), the key should be destroyed when all accesses have
     * stopped.
     */
    if (slot->lock_count > 1) {
        psa_unlock_key_slot(slot);
        return (PSA_ERROR_GENERIC_ERROR);
    }

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    driver = psa_get_se_driver_entry(slot->attr.lifetime);
    if (driver != NULL) {
        /* For a key in a secure element, we need to do three things:
         * remove the key file in internal storage, destroy the
         * key inside the secure element, and update the driver's
         * persistent data. Start a transaction that will encompass these
         * three actions. */
        psa_crypto_prepare_transaction(PSA_CRYPTO_TRANSACTION_DESTROY_KEY);
        psa_crypto_transaction.key.lifetime = slot->attr.lifetime;
        psa_crypto_transaction.key.slot = psa_key_slot_get_slot_number(slot);
        psa_crypto_transaction.key.id = slot->attr.id;
        status = psa_crypto_save_transaction();
        if (status != PSA_SUCCESS) {
            (void) psa_crypto_stop_transaction();
            /* We should still try to destroy the key in the secure
             * element and the key metadata in storage. This is especially
             * important if the error is that the storage is full.
             * But how to do it exactly without risking an inconsistent
             * state after a reset?
             * https://github.com/ARMmbed/mbed-crypto/issues/215
             */
            overall_status = status;
            goto exit;
        }

        status = psa_destroy_se_key(driver,
                                    psa_key_slot_get_slot_number(slot));
        if (overall_status == PSA_SUCCESS)
            overall_status = status;
    }
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
    if (! PSA_KEY_LIFETIME_IS_VOLATILE(slot->attr.lifetime)) {
        status = psa_destroy_persistent_key(slot->attr.id);
        if (overall_status == PSA_SUCCESS)
            overall_status = status;

        /* TODO: other slots may have a copy of the same key. We should
         * invalidate them.
         * https://github.com/ARMmbed/mbed-crypto/issues/214
         */
    }
#endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    if (driver != NULL) {
        status = psa_save_se_persistent_data(driver);
        if (overall_status == PSA_SUCCESS)
            overall_status = status;
        status = psa_crypto_stop_transaction();
        if (overall_status == PSA_SUCCESS)
            overall_status = status;
    }
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
exit:
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
    status = psa_wipe_key_slot(slot);
    /* Prioritize CORRUPTION_DETECTED from wiping over a storage error */
    if (overall_status == PSA_SUCCESS)
        overall_status = status;
    return (overall_status);
}

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) || \
    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY)
static psa_status_t psa_get_rsa_public_exponent(
    const mbedtls_rsa_context *rsa,
    psa_key_attributes_t *attributes) {
    mbedtls_mpi mpi;
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    uint8_t *buffer = NULL;
    size_t buflen;
    mbedtls_mpi_init(&mpi);

    ret = mbedtls_rsa_export(rsa, NULL, NULL, NULL, NULL, &mpi);
    if (ret != 0)
        goto exit;
    if (mbedtls_mpi_cmp_int(&mpi, 65537) == 0) {
        /* It's the default value, which is reported as an empty string,
         * so there's nothing to do. */
        goto exit;
    }

    buflen = mbedtls_mpi_size(&mpi);
    buffer = mbedtls_calloc(1, buflen);
    if (buffer == NULL) {
        ret = MBEDTLS_ERR_MPI_ALLOC_FAILED;
        goto exit;
    }
    ret = mbedtls_mpi_write_binary(&mpi, buffer, buflen);
    if (ret != 0)
        goto exit;
    attributes->domain_parameters = buffer;
    attributes->domain_parameters_size = buflen;

exit:
    mbedtls_mpi_free(&mpi);
    if (ret != 0)
        mbedtls_free(buffer);
    return (mbedtls_to_psa_error(ret));
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) ||
        * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY) */

/** Retrieve all the publicly-accessible attributes of a key.
 */
psa_status_t psa_get_key_attributes(mbedtls_svc_key_id_t key,
                                    psa_key_attributes_t *attributes) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    psa_reset_key_attributes(attributes);

    status = psa_get_and_lock_key_slot_with_policy(key, &slot, 0, 0);
    if (status != PSA_SUCCESS)
        return (status);

    attributes->core = slot->attr;
    attributes->core.flags &= (MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY |
                               MBEDTLS_PSA_KA_MASK_DUAL_USE);

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    if (psa_key_slot_is_external(slot))
        psa_set_key_slot_number(attributes,
                                psa_key_slot_get_slot_number(slot));
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

    switch (slot->attr.type) {
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) || \
    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY)
        case PSA_KEY_TYPE_RSA_KEY_PAIR:
        case PSA_KEY_TYPE_RSA_PUBLIC_KEY:
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
            /* TODO: reporting the public exponent for opaque keys
             * is not yet implemented.
             * https://github.com/ARMmbed/mbed-crypto/issues/216
             */
            if (psa_key_slot_is_external(slot))
                break;
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
            {
                mbedtls_rsa_context *rsa = NULL;

                status = mbedtls_psa_rsa_load_representation(
                             slot->attr.type,
                             slot->key.data,
                             slot->key.bytes,
                             &rsa);
                if (status != PSA_SUCCESS)
                    break;

                status = psa_get_rsa_public_exponent(rsa,
                                                     attributes);
                mbedtls_rsa_free(rsa);
                mbedtls_free(rsa);
            }
            break;
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) ||
        * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY) */
        default:
            /* Nothing else to do. */
            break;
    }

    if (status != PSA_SUCCESS)
        psa_reset_key_attributes(attributes);

    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
psa_status_t psa_get_key_slot_number(
    const psa_key_attributes_t *attributes,
    psa_key_slot_number_t *slot_number) {
    if (attributes->core.flags & MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER) {
        *slot_number = attributes->slot_number;
        return (PSA_SUCCESS);
    } else
        return (PSA_ERROR_INVALID_ARGUMENT);
}
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

static psa_status_t psa_export_key_buffer_internal(const uint8_t *key_buffer,
                                                   size_t key_buffer_size,
                                                   uint8_t *data,
                                                   size_t data_size,
                                                   size_t *data_length) {
    if (key_buffer_size > data_size)
        return (PSA_ERROR_BUFFER_TOO_SMALL);
    memcpy(data, key_buffer, key_buffer_size);
    memset(data + key_buffer_size, 0,
           data_size - key_buffer_size);
    *data_length = key_buffer_size;
    return (PSA_SUCCESS);
}

psa_status_t psa_export_key_internal(
    const psa_key_attributes_t *attributes,
    const uint8_t *key_buffer, size_t key_buffer_size,
    uint8_t *data, size_t data_size, size_t *data_length) {
    psa_key_type_t type = attributes->core.type;

    if (key_type_is_raw_bytes(type) ||
            PSA_KEY_TYPE_IS_RSA(type)   ||
            PSA_KEY_TYPE_IS_ECC(type)) {
        return (psa_export_key_buffer_internal(
                    key_buffer, key_buffer_size,
                    data, data_size, data_length));
    } else {
        /* This shouldn't happen in the reference implementation, but
           it is valid for a special-purpose implementation to omit
           support for exporting certain key types. */
        return (PSA_ERROR_NOT_SUPPORTED);
    }
}

psa_status_t psa_export_key(mbedtls_svc_key_id_t key,
                            uint8_t *data,
                            size_t data_size,
                            size_t *data_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    /* Reject a zero-length output buffer now, since this can never be a
     * valid key representation. This way we know that data must be a valid
     * pointer and we can do things like memset(data, ..., data_size). */
    if (data_size == 0)
        return (PSA_ERROR_BUFFER_TOO_SMALL);

    /* Set the key to empty now, so that even when there are errors, we always
     * set data_length to a value between 0 and data_size. On error, setting
     * the key to empty is a good choice because an empty key representation is
     * unlikely to be accepted anywhere. */
    *data_length = 0;

    /* Export requires the EXPORT flag. There is an exception for public keys,
     * which don't require any flag, but
     * psa_get_and_lock_key_slot_with_policy() takes care of this.
     */
    status = psa_get_and_lock_key_slot_with_policy(key, &slot,
                                                   PSA_KEY_USAGE_EXPORT, 0);
    if (status != PSA_SUCCESS)
        return (status);

    psa_key_attributes_t attributes = {
        .core = slot->attr
    };
    status = psa_driver_wrapper_export_key(&attributes,
                                           slot->key.data, slot->key.bytes,
                                           data, data_size, data_length);

    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}

psa_status_t psa_export_public_key_internal(
    const psa_key_attributes_t *attributes,
    const uint8_t *key_buffer,
    size_t key_buffer_size,
    uint8_t *data,
    size_t data_size,
    size_t *data_length) {
    psa_key_type_t type = attributes->core.type;

    if (PSA_KEY_TYPE_IS_RSA(type) || PSA_KEY_TYPE_IS_ECC(type)) {
        if (PSA_KEY_TYPE_IS_PUBLIC_KEY(type)) {
            /* Exporting public -> public */
            return (psa_export_key_buffer_internal(
                        key_buffer, key_buffer_size,
                        data, data_size, data_length));
        }

        if (PSA_KEY_TYPE_IS_RSA(type)) {
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) || \
    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY)
            return (mbedtls_psa_rsa_export_public_key(attributes,
                                                      key_buffer,
                                                      key_buffer_size,
                                                      data,
                                                      data_size,
                                                      data_length));
#else
            /* We don't know how to convert a private RSA key to public. */
            return (PSA_ERROR_NOT_SUPPORTED);
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) ||
        * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY) */
        } else {
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) || \
    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY)
            return (mbedtls_psa_ecp_export_public_key(attributes,
                                                      key_buffer,
                                                      key_buffer_size,
                                                      data,
                                                      data_size,
                                                      data_length));
#else
            /* We don't know how to convert a private ECC key to public */
            return (PSA_ERROR_NOT_SUPPORTED);
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) ||
        * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_PUBLIC_KEY) */
        }
    } else {
        /* This shouldn't happen in the reference implementation, but
           it is valid for a special-purpose implementation to omit
           support for exporting certain key types. */
        return (PSA_ERROR_NOT_SUPPORTED);
    }
}

psa_status_t psa_export_public_key(mbedtls_svc_key_id_t key,
                                   uint8_t *data,
                                   size_t data_size,
                                   size_t *data_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    /* Reject a zero-length output buffer now, since this can never be a
     * valid key representation. This way we know that data must be a valid
     * pointer and we can do things like memset(data, ..., data_size). */
    if (data_size == 0)
        return (PSA_ERROR_BUFFER_TOO_SMALL);

    /* Set the key to empty now, so that even when there are errors, we always
     * set data_length to a value between 0 and data_size. On error, setting
     * the key to empty is a good choice because an empty key representation is
     * unlikely to be accepted anywhere. */
    *data_length = 0;

    /* Exporting a public key doesn't require a usage flag. */
    status = psa_get_and_lock_key_slot_with_policy(key, &slot, 0, 0);
    if (status != PSA_SUCCESS)
        return (status);

    if (! PSA_KEY_TYPE_IS_ASYMMETRIC(slot->attr.type)) {
        status = PSA_ERROR_INVALID_ARGUMENT;
        goto exit;
    }

    psa_key_attributes_t attributes = {
        .core = slot->attr
    };
    status = psa_driver_wrapper_export_public_key(
                 &attributes, slot->key.data, slot->key.bytes,
                 data, data_size, data_length);

exit:
    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}

#if defined(static_assert)
static_assert((MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY &MBEDTLS_PSA_KA_MASK_DUAL_USE) == 0,
              "One or more key attribute flag is listed as both external-only and dual-use");
static_assert((PSA_KA_MASK_INTERNAL_ONLY &MBEDTLS_PSA_KA_MASK_DUAL_USE) == 0,
              "One or more key attribute flag is listed as both internal-only and dual-use");
static_assert((PSA_KA_MASK_INTERNAL_ONLY &MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY) == 0,
              "One or more key attribute flag is listed as both internal-only and external-only");
#endif

/** Validate that a key policy is internally well-formed.
 *
 * This function only rejects invalid policies. It does not validate the
 * consistency of the policy with respect to other attributes of the key
 * such as the key type.
 */
static psa_status_t psa_validate_key_policy(const psa_key_policy_t *policy) {
    if ((policy->usage & ~(PSA_KEY_USAGE_EXPORT |
                           PSA_KEY_USAGE_COPY |
                           PSA_KEY_USAGE_ENCRYPT |
                           PSA_KEY_USAGE_DECRYPT |
                           PSA_KEY_USAGE_SIGN_HASH |
                           PSA_KEY_USAGE_VERIFY_HASH |
                           PSA_KEY_USAGE_DERIVE)) != 0)
        return (PSA_ERROR_INVALID_ARGUMENT);

    return (PSA_SUCCESS);
}

/** Validate the internal consistency of key attributes.
 *
 * This function only rejects invalid attribute values. If does not
 * validate the consistency of the attributes with any key data that may
 * be involved in the creation of the key.
 *
 * Call this function early in the key creation process.
 *
 * \param[in] attributes    Key attributes for the new key.
 * \param[out] p_drv        On any return, the driver for the key, if any.
 *                          NULL for a transparent key.
 *
 */
static psa_status_t psa_validate_key_attributes(
    const psa_key_attributes_t *attributes,
    psa_se_drv_table_entry_t **p_drv) {
    psa_status_t status = PSA_ERROR_INVALID_ARGUMENT;
    psa_key_lifetime_t lifetime = psa_get_key_lifetime(attributes);
    mbedtls_svc_key_id_t key = psa_get_key_id(attributes);

    status = psa_validate_key_location(lifetime, p_drv);
    if (status != PSA_SUCCESS)
        return (status);

    status = psa_validate_key_persistence(lifetime);
    if (status != PSA_SUCCESS)
        return (status);

    if (PSA_KEY_LIFETIME_IS_VOLATILE(lifetime)) {
        if (MBEDTLS_SVC_KEY_ID_GET_KEY_ID(key) != 0)
            return (PSA_ERROR_INVALID_ARGUMENT);
    } else {
        status = psa_validate_key_id(psa_get_key_id(attributes), 0);
        if (status != PSA_SUCCESS)
            return (status);
    }

    status = psa_validate_key_policy(&attributes->core.policy);
    if (status != PSA_SUCCESS)
        return (status);

    /* Refuse to create overly large keys.
     * Note that this doesn't trigger on import if the attributes don't
     * explicitly specify a size (so psa_get_key_bits returns 0), so
     * psa_import_key() needs its own checks. */
    if (psa_get_key_bits(attributes) > PSA_MAX_KEY_BITS)
        return (PSA_ERROR_NOT_SUPPORTED);

    /* Reject invalid flags. These should not be reachable through the API. */
    if (attributes->core.flags & ~(MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY |
                                   MBEDTLS_PSA_KA_MASK_DUAL_USE))
        return (PSA_ERROR_INVALID_ARGUMENT);

    return (PSA_SUCCESS);
}

/** Prepare a key slot to receive key material.
 *
 * This function allocates a key slot and sets its metadata.
 *
 * If this function fails, call psa_fail_key_creation().
 *
 * This function is intended to be used as follows:
 * -# Call psa_start_key_creation() to allocate a key slot, prepare
 *    it with the specified attributes, and in case of a volatile key assign it
 *    a volatile key identifier.
 * -# Populate the slot with the key material.
 * -# Call psa_finish_key_creation() to finalize the creation of the slot.
 * In case of failure at any step, stop the sequence and call
 * psa_fail_key_creation().
 *
 * On success, the key slot is locked. It is the responsibility of the caller
 * to unlock the key slot when it does not access it anymore.
 *
 * \param method            An identification of the calling function.
 * \param[in] attributes    Key attributes for the new key.
 * \param[out] p_slot       On success, a pointer to the prepared slot.
 * \param[out] p_drv        On any return, the driver for the key, if any.
 *                          NULL for a transparent key.
 *
 * \retval #PSA_SUCCESS
 *         The key slot is ready to receive key material.
 * \return If this function fails, the key slot is an invalid state.
 *         You must call psa_fail_key_creation() to wipe and free the slot.
 */
static psa_status_t psa_start_key_creation(
    psa_key_creation_method_t method,
    const psa_key_attributes_t *attributes,
    psa_key_slot_t **p_slot,
    psa_se_drv_table_entry_t **p_drv) {
    psa_status_t status;
    psa_key_id_t volatile_key_id;
    psa_key_slot_t *slot;

    (void) method;
    *p_drv = NULL;

    status = psa_validate_key_attributes(attributes, p_drv);
    if (status != PSA_SUCCESS)
        return (status);

    status = psa_get_empty_key_slot(&volatile_key_id, p_slot);
    if (status != PSA_SUCCESS)
        return (status);
    slot = *p_slot;

    /* We're storing the declared bit-size of the key. It's up to each
     * creation mechanism to verify that this information is correct.
     * It's automatically correct for mechanisms that use the bit-size as
     * an input (generate, device) but not for those where the bit-size
     * is optional (import, copy). In case of a volatile key, assign it the
     * volatile key identifier associated to the slot returned to contain its
     * definition. */

    slot->attr = attributes->core;
    if (PSA_KEY_LIFETIME_IS_VOLATILE(slot->attr.lifetime)) {
#if !defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER)
        slot->attr.id = volatile_key_id;
#else
        slot->attr.id.key_id = volatile_key_id;
#endif
    }

    /* Erase external-only flags from the internal copy. To access
     * external-only flags, query `attributes`. Thanks to the check
     * in psa_validate_key_attributes(), this leaves the dual-use
     * flags and any internal flag that psa_get_empty_key_slot()
     * may have set. */
    slot->attr.flags &= ~MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY;

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    /* For a key in a secure element, we need to do three things
     * when creating or registering a persistent key:
     * create the key file in internal storage, create the
     * key inside the secure element, and update the driver's
     * persistent data. This is done by starting a transaction that will
     * encompass these three actions.
     * For registering a volatile key, we just need to find an appropriate
     * slot number inside the SE. Since the key is designated volatile, creating
     * a transaction is not required. */
    /* The first thing to do is to find a slot number for the new key.
     * We save the slot number in persistent storage as part of the
     * transaction data. It will be needed to recover if the power
     * fails during the key creation process, to clean up on the secure
     * element side after restarting. Obtaining a slot number from the
     * secure element driver updates its persistent state, but we do not yet
     * save the driver's persistent state, so that if the power fails,
     * we can roll back to a state where the key doesn't exist. */
    if (*p_drv != NULL) {
        psa_key_slot_number_t slot_number;
        status = psa_find_se_slot_for_key(attributes, method, *p_drv,
                                          &slot_number);
        if (status != PSA_SUCCESS)
            return (status);

        if (! PSA_KEY_LIFETIME_IS_VOLATILE(attributes->core.lifetime)) {
            psa_crypto_prepare_transaction(PSA_CRYPTO_TRANSACTION_CREATE_KEY);
            psa_crypto_transaction.key.lifetime = slot->attr.lifetime;
            psa_crypto_transaction.key.slot = slot_number;
            psa_crypto_transaction.key.id = slot->attr.id;
            status = psa_crypto_save_transaction();
            if (status != PSA_SUCCESS) {
                (void) psa_crypto_stop_transaction();
                return (status);
            }
        }

        status = psa_copy_key_material_into_slot(
                     slot, (uint8_t *)(&slot_number), sizeof(slot_number));
    }

    if (*p_drv == NULL && method == PSA_KEY_CREATION_REGISTER) {
        /* Key registration only makes sense with a secure element. */
        return (PSA_ERROR_INVALID_ARGUMENT);
    }
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

    return (PSA_SUCCESS);
}

/** Finalize the creation of a key once its key material has been set.
 *
 * This entails writing the key to persistent storage.
 *
 * If this function fails, call psa_fail_key_creation().
 * See the documentation of psa_start_key_creation() for the intended use
 * of this function.
 *
 * If the finalization succeeds, the function unlocks the key slot (it was
 * locked by psa_start_key_creation()) and the key slot cannot be accessed
 * anymore as part of the key creation process.
 *
 * \param[in,out] slot  Pointer to the slot with key material.
 * \param[in] driver    The secure element driver for the key,
 *                      or NULL for a transparent key.
 * \param[out] key      On success, identifier of the key. Note that the
 *                      key identifier is also stored in the key slot.
 *
 * \retval #PSA_SUCCESS
 *         The key was successfully created.
 * \retval #PSA_ERROR_INSUFFICIENT_MEMORY
 * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
 * \retval #PSA_ERROR_ALREADY_EXISTS
 * \retval #PSA_ERROR_DATA_INVALID
 * \retval #PSA_ERROR_DATA_CORRUPT
 * \retval #PSA_ERROR_STORAGE_FAILURE
 *
 * \return If this function fails, the key slot is an invalid state.
 *         You must call psa_fail_key_creation() to wipe and free the slot.
 */
static psa_status_t psa_finish_key_creation(
    psa_key_slot_t *slot,
    psa_se_drv_table_entry_t *driver,
    mbedtls_svc_key_id_t *key) {
    psa_status_t status = PSA_SUCCESS;
    (void) slot;
    (void) driver;

#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
    if (! PSA_KEY_LIFETIME_IS_VOLATILE(slot->attr.lifetime)) {
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
        if (driver != NULL) {
            psa_se_key_data_storage_t data;
            psa_key_slot_number_t slot_number =
                psa_key_slot_get_slot_number(slot) ;

#if defined(static_assert)
            static_assert(sizeof(slot_number) ==
                          sizeof(data.slot_number),
                          "Slot number size does not match psa_se_key_data_storage_t");
#endif
            memcpy(&data.slot_number, &slot_number, sizeof(slot_number));
            status = psa_save_persistent_key(&slot->attr,
                                             (uint8_t *) &data,
                                             sizeof(data));
        } else
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
        {
            /* Key material is saved in export representation in the slot, so
             * just pass the slot buffer for storage. */
            status = psa_save_persistent_key(&slot->attr,
                                             slot->key.data,
                                             slot->key.bytes);
        }
    }
#endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    /* Finish the transaction for a key creation. This does not
     * happen when registering an existing key. Detect this case
     * by checking whether a transaction is in progress (actual
     * creation of a persistent key in a secure element requires a transaction,
     * but registration or volatile key creation doesn't use one). */
    if (driver != NULL &&
            psa_crypto_transaction.unknown.type == PSA_CRYPTO_TRANSACTION_CREATE_KEY) {
        status = psa_save_se_persistent_data(driver);
        if (status != PSA_SUCCESS) {
            psa_destroy_persistent_key(slot->attr.id);
            return (status);
        }
        status = psa_crypto_stop_transaction();
    }
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

    if (status == PSA_SUCCESS) {
        *key = slot->attr.id;
        status = psa_unlock_key_slot(slot);
        if (status != PSA_SUCCESS)
            *key = MBEDTLS_SVC_KEY_ID_INIT;
    }

    return (status);
}

/** Abort the creation of a key.
 *
 * You may call this function after calling psa_start_key_creation(),
 * or after psa_finish_key_creation() fails. In other circumstances, this
 * function may not clean up persistent storage.
 * See the documentation of psa_start_key_creation() for the intended use
 * of this function.
 *
 * \param[in,out] slot  Pointer to the slot with key material.
 * \param[in] driver    The secure element driver for the key,
 *                      or NULL for a transparent key.
 */
static void psa_fail_key_creation(psa_key_slot_t *slot,
                                  psa_se_drv_table_entry_t *driver) {
    (void) driver;

    if (slot == NULL)
        return;

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    /* TODO: If the key has already been created in the secure
     * element, and the failure happened later (when saving metadata
     * to internal storage), we need to destroy the key in the secure
     * element.
     * https://github.com/ARMmbed/mbed-crypto/issues/217
     */

    /* Abort the ongoing transaction if any (there may not be one if
     * the creation process failed before starting one, or if the
     * key creation is a registration of a key in a secure element).
     * Earlier functions must already have done what it takes to undo any
     * partial creation. All that's left is to update the transaction data
     * itself. */
    (void) psa_crypto_stop_transaction();
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

    psa_wipe_key_slot(slot);
}

/** Validate optional attributes during key creation.
 *
 * Some key attributes are optional during key creation. If they are
 * specified in the attributes structure, check that they are consistent
 * with the data in the slot.
 *
 * This function should be called near the end of key creation, after
 * the slot in memory is fully populated but before saving persistent data.
 */
static psa_status_t psa_validate_optional_attributes(
    const psa_key_slot_t *slot,
    const psa_key_attributes_t *attributes) {
    if (attributes->core.type != 0) {
        if (attributes->core.type != slot->attr.type)
            return (PSA_ERROR_INVALID_ARGUMENT);
    }

    if (attributes->domain_parameters_size != 0) {
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) || \
    defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY)
        if (PSA_KEY_TYPE_IS_RSA(slot->attr.type)) {
            mbedtls_rsa_context *rsa = NULL;
            mbedtls_mpi actual, required;
            int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

            psa_status_t status = mbedtls_psa_rsa_load_representation(
                                      slot->attr.type,
                                      slot->key.data,
                                      slot->key.bytes,
                                      &rsa);
            if (status != PSA_SUCCESS)
                return (status);

            mbedtls_mpi_init(&actual);
            mbedtls_mpi_init(&required);
            ret = mbedtls_rsa_export(rsa,
                                     NULL, NULL, NULL, NULL, &actual);
            mbedtls_rsa_free(rsa);
            mbedtls_free(rsa);
            if (ret != 0)
                goto rsa_exit;
            ret = mbedtls_mpi_read_binary(&required,
                                          attributes->domain_parameters,
                                          attributes->domain_parameters_size);
            if (ret != 0)
                goto rsa_exit;
            if (mbedtls_mpi_cmp_mpi(&actual, &required) != 0)
                ret = MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
rsa_exit:
            mbedtls_mpi_free(&actual);
            mbedtls_mpi_free(&required);
            if (ret != 0)
                return (mbedtls_to_psa_error(ret));
        } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) ||
        * defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_PUBLIC_KEY) */
        {
            return (PSA_ERROR_INVALID_ARGUMENT);
        }
    }

    if (attributes->core.bits != 0) {
        if (attributes->core.bits != slot->attr.bits)
            return (PSA_ERROR_INVALID_ARGUMENT);
    }

    return (PSA_SUCCESS);
}

psa_status_t psa_import_key(const psa_key_attributes_t *attributes,
                            const uint8_t *data,
                            size_t data_length,
                            mbedtls_svc_key_id_t *key) {
    psa_status_t status;
    psa_key_slot_t *slot = NULL;
    psa_se_drv_table_entry_t *driver = NULL;
    size_t bits;

    *key = MBEDTLS_SVC_KEY_ID_INIT;

    /* Reject zero-length symmetric keys (including raw data key objects).
     * This also rejects any key which might be encoded as an empty string,
     * which is never valid. */
    if (data_length == 0)
        return (PSA_ERROR_INVALID_ARGUMENT);

    status = psa_start_key_creation(PSA_KEY_CREATION_IMPORT, attributes,
                                    &slot, &driver);
    if (status != PSA_SUCCESS)
        goto exit;

    /* In the case of a transparent key or an opaque key stored in local
     * storage (thus not in the case of generating a key in a secure element
     * or cryptoprocessor with storage), we have to allocate a buffer to
     * hold the generated key material. */
    if (slot->key.data == NULL) {
        status = psa_allocate_buffer_to_slot(slot, data_length);
        if (status != PSA_SUCCESS)
            goto exit;
    }

    bits = slot->attr.bits;
    status = psa_driver_wrapper_import_key(attributes,
                                           data, data_length,
                                           slot->key.data,
                                           slot->key.bytes,
                                           &slot->key.bytes, &bits);
    if (status != PSA_SUCCESS)
        goto exit;

    if (slot->attr.bits == 0)
        slot->attr.bits = (psa_key_bits_t) bits;
    else if (bits != slot->attr.bits) {
        status = PSA_ERROR_INVALID_ARGUMENT;
        goto exit;
    }

    status = psa_validate_optional_attributes(slot, attributes);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_finish_key_creation(slot, driver, key);
exit:
    if (status != PSA_SUCCESS)
        psa_fail_key_creation(slot, driver);

    return (status);
}

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
psa_status_t mbedtls_psa_register_se_key(
    const psa_key_attributes_t *attributes) {
    psa_status_t status;
    psa_key_slot_t *slot = NULL;
    psa_se_drv_table_entry_t *driver = NULL;
    mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT;

    /* Leaving attributes unspecified is not currently supported.
     * It could make sense to query the key type and size from the
     * secure element, but not all secure elements support this
     * and the driver HAL doesn't currently support it. */
    if (psa_get_key_type(attributes) == PSA_KEY_TYPE_NONE)
        return (PSA_ERROR_NOT_SUPPORTED);
    if (psa_get_key_bits(attributes) == 0)
        return (PSA_ERROR_NOT_SUPPORTED);

    status = psa_start_key_creation(PSA_KEY_CREATION_REGISTER, attributes,
                                    &slot, &driver);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_finish_key_creation(slot, driver, &key);

exit:
    if (status != PSA_SUCCESS)
        psa_fail_key_creation(slot, driver);

    /* Registration doesn't keep the key in RAM. */
    psa_close_key(key);
    return (status);
}
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

static psa_status_t psa_copy_key_material(const psa_key_slot_t *source,
                                          psa_key_slot_t *target) {
    psa_status_t status = psa_copy_key_material_into_slot(target,
                                                          source->key.data,
                                                          source->key.bytes);
    if (status != PSA_SUCCESS)
        return (status);

    target->attr.type = source->attr.type;
    target->attr.bits = source->attr.bits;

    return (PSA_SUCCESS);
}

psa_status_t psa_copy_key(mbedtls_svc_key_id_t source_key,
                          const psa_key_attributes_t *specified_attributes,
                          mbedtls_svc_key_id_t *target_key) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *source_slot = NULL;
    psa_key_slot_t *target_slot = NULL;
    psa_key_attributes_t actual_attributes = *specified_attributes;
    psa_se_drv_table_entry_t *driver = NULL;

    *target_key = MBEDTLS_SVC_KEY_ID_INIT;

    status = psa_get_and_lock_transparent_key_slot_with_policy(
                 source_key, &source_slot, PSA_KEY_USAGE_COPY, 0);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_validate_optional_attributes(source_slot,
                                              specified_attributes);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_restrict_key_policy(source_slot->attr.type,
                                     &actual_attributes.core.policy,
                                     &source_slot->attr.policy);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_start_key_creation(PSA_KEY_CREATION_COPY, &actual_attributes,
                                    &target_slot, &driver);
    if (status != PSA_SUCCESS)
        goto exit;

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    if (driver != NULL) {
        /* Copying to a secure element is not implemented yet. */
        status = PSA_ERROR_NOT_SUPPORTED;
        goto exit;
    }
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

    status = psa_copy_key_material(source_slot, target_slot);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_finish_key_creation(target_slot, driver, target_key);
exit:
    if (status != PSA_SUCCESS)
        psa_fail_key_creation(target_slot, driver);

    unlock_status = psa_unlock_key_slot(source_slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}



/****************************************************************/
/* Message digests */
/****************************************************************/

#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA)
const mbedtls_md_info_t *mbedtls_md_info_from_psa(psa_algorithm_t alg) {
    switch (alg) {
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD2)
        case PSA_ALG_MD2:
            return (&mbedtls_md2_info);
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD4)
        case PSA_ALG_MD4:
            return (&mbedtls_md4_info);
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD5)
        case PSA_ALG_MD5:
            return (&mbedtls_md5_info);
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RIPEMD160)
        case PSA_ALG_RIPEMD160:
            return (&mbedtls_ripemd160_info);
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_1)
        case PSA_ALG_SHA_1:
            return (&mbedtls_sha1_info);
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_224)
        case PSA_ALG_SHA_224:
            return (&mbedtls_sha224_info);
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_256)
        case PSA_ALG_SHA_256:
            return (&mbedtls_sha256_info);
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_384)
        case PSA_ALG_SHA_384:
            return (&mbedtls_sha384_info);
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_512)
        case PSA_ALG_SHA_512:
            return (&mbedtls_sha512_info);
#endif
        default:
            return (NULL);
    }
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA) */

psa_status_t psa_hash_abort(psa_hash_operation_t *operation) {
    switch (operation->alg) {
        case 0:
            /* The object has (apparently) been initialized but it is not
             * in use. It's ok to call abort on such an object, and there's
             * nothing to do. */
            break;
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD2)
        case PSA_ALG_MD2:
            mbedtls_md2_free(&operation->ctx.md2);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD4)
        case PSA_ALG_MD4:
            mbedtls_md4_free(&operation->ctx.md4);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD5)
        case PSA_ALG_MD5:
            mbedtls_md5_free(&operation->ctx.md5);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RIPEMD160)
        case PSA_ALG_RIPEMD160:
            mbedtls_ripemd160_free(&operation->ctx.ripemd160);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_1)
        case PSA_ALG_SHA_1:
            mbedtls_sha1_free(&operation->ctx.sha1);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_224)
        case PSA_ALG_SHA_224:
            mbedtls_sha256_free(&operation->ctx.sha256);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_256)
        case PSA_ALG_SHA_256:
            mbedtls_sha256_free(&operation->ctx.sha256);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_384)
        case PSA_ALG_SHA_384:
            mbedtls_sha512_free(&operation->ctx.sha512);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_512)
        case PSA_ALG_SHA_512:
            mbedtls_sha512_free(&operation->ctx.sha512);
            break;
#endif
        default:
            return (PSA_ERROR_BAD_STATE);
    }
    operation->alg = 0;
    return (PSA_SUCCESS);
}

psa_status_t psa_hash_setup(psa_hash_operation_t *operation,
                            psa_algorithm_t alg) {
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    /* A context must be freshly initialized before it can be set up. */
    if (operation->alg != 0) {
        return (PSA_ERROR_BAD_STATE);
    }

    switch (alg) {
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD2)
        case PSA_ALG_MD2:
            mbedtls_md2_init(&operation->ctx.md2);
            ret = mbedtls_md2_starts_ret(&operation->ctx.md2);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD4)
        case PSA_ALG_MD4:
            mbedtls_md4_init(&operation->ctx.md4);
            ret = mbedtls_md4_starts_ret(&operation->ctx.md4);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD5)
        case PSA_ALG_MD5:
            mbedtls_md5_init(&operation->ctx.md5);
            ret = mbedtls_md5_starts_ret(&operation->ctx.md5);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RIPEMD160)
        case PSA_ALG_RIPEMD160:
            mbedtls_ripemd160_init(&operation->ctx.ripemd160);
            ret = mbedtls_ripemd160_starts_ret(&operation->ctx.ripemd160);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_1)
        case PSA_ALG_SHA_1:
            mbedtls_sha1_init(&operation->ctx.sha1);
            ret = mbedtls_sha1_starts_ret(&operation->ctx.sha1);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_224)
        case PSA_ALG_SHA_224:
            mbedtls_sha256_init(&operation->ctx.sha256);
            ret = mbedtls_sha256_starts_ret(&operation->ctx.sha256, 1);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_256)
        case PSA_ALG_SHA_256:
            mbedtls_sha256_init(&operation->ctx.sha256);
            ret = mbedtls_sha256_starts_ret(&operation->ctx.sha256, 0);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_384)
        case PSA_ALG_SHA_384:
            mbedtls_sha512_init(&operation->ctx.sha512);
            ret = mbedtls_sha512_starts_ret(&operation->ctx.sha512, 1);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_512)
        case PSA_ALG_SHA_512:
            mbedtls_sha512_init(&operation->ctx.sha512);
            ret = mbedtls_sha512_starts_ret(&operation->ctx.sha512, 0);
            break;
#endif
        default:
            return (PSA_ALG_IS_HASH(alg) ?
                    PSA_ERROR_NOT_SUPPORTED :
                    PSA_ERROR_INVALID_ARGUMENT);
    }
    if (ret == 0)
        operation->alg = alg;
    else
        psa_hash_abort(operation);
    return (mbedtls_to_psa_error(ret));
}

psa_status_t psa_hash_update(psa_hash_operation_t *operation,
                             const uint8_t *input,
                             size_t input_length) {
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    /* Don't require hash implementations to behave correctly on a
     * zero-length input, which may have an invalid pointer. */
    if (input_length == 0)
        return (PSA_SUCCESS);

    switch (operation->alg) {
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD2)
        case PSA_ALG_MD2:
            ret = mbedtls_md2_update_ret(&operation->ctx.md2,
                                         input, input_length);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD4)
        case PSA_ALG_MD4:
            ret = mbedtls_md4_update_ret(&operation->ctx.md4,
                                         input, input_length);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD5)
        case PSA_ALG_MD5:
            ret = mbedtls_md5_update_ret(&operation->ctx.md5,
                                         input, input_length);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RIPEMD160)
        case PSA_ALG_RIPEMD160:
            ret = mbedtls_ripemd160_update_ret(&operation->ctx.ripemd160,
                                               input, input_length);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_1)
        case PSA_ALG_SHA_1:
            ret = mbedtls_sha1_update_ret(&operation->ctx.sha1,
                                          input, input_length);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_224)
        case PSA_ALG_SHA_224:
            ret = mbedtls_sha256_update_ret(&operation->ctx.sha256,
                                            input, input_length);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_256)
        case PSA_ALG_SHA_256:
            ret = mbedtls_sha256_update_ret(&operation->ctx.sha256,
                                            input, input_length);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_384)
        case PSA_ALG_SHA_384:
            ret = mbedtls_sha512_update_ret(&operation->ctx.sha512,
                                            input, input_length);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_512)
        case PSA_ALG_SHA_512:
            ret = mbedtls_sha512_update_ret(&operation->ctx.sha512,
                                            input, input_length);
            break;
#endif
        default:
            (void)input;
            return (PSA_ERROR_BAD_STATE);
    }

    if (ret != 0)
        psa_hash_abort(operation);
    return (mbedtls_to_psa_error(ret));
}

psa_status_t psa_hash_finish(psa_hash_operation_t *operation,
                             uint8_t *hash,
                             size_t hash_size,
                             size_t *hash_length) {
    psa_status_t status;
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    size_t actual_hash_length = PSA_HASH_LENGTH(operation->alg);

    /* Fill the output buffer with something that isn't a valid hash
     * (barring an attack on the hash and deliberately-crafted input),
     * in case the caller doesn't check the return status properly. */
    *hash_length = hash_size;
    /* If hash_size is 0 then hash may be NULL and then the
     * call to memset would have undefined behavior. */
    if (hash_size != 0)
        memset(hash, '!', hash_size);

    if (hash_size < actual_hash_length) {
        status = PSA_ERROR_BUFFER_TOO_SMALL;
        goto exit;
    }

    switch (operation->alg) {
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD2)
        case PSA_ALG_MD2:
            ret = mbedtls_md2_finish_ret(&operation->ctx.md2, hash);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD4)
        case PSA_ALG_MD4:
            ret = mbedtls_md4_finish_ret(&operation->ctx.md4, hash);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD5)
        case PSA_ALG_MD5:
            ret = mbedtls_md5_finish_ret(&operation->ctx.md5, hash);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RIPEMD160)
        case PSA_ALG_RIPEMD160:
            ret = mbedtls_ripemd160_finish_ret(&operation->ctx.ripemd160, hash);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_1)
        case PSA_ALG_SHA_1:
            ret = mbedtls_sha1_finish_ret(&operation->ctx.sha1, hash);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_224)
        case PSA_ALG_SHA_224:
            ret = mbedtls_sha256_finish_ret(&operation->ctx.sha256, hash);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_256)
        case PSA_ALG_SHA_256:
            ret = mbedtls_sha256_finish_ret(&operation->ctx.sha256, hash);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_384)
        case PSA_ALG_SHA_384:
            ret = mbedtls_sha512_finish_ret(&operation->ctx.sha512, hash);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_512)
        case PSA_ALG_SHA_512:
            ret = mbedtls_sha512_finish_ret(&operation->ctx.sha512, hash);
            break;
#endif
        default:
            return (PSA_ERROR_BAD_STATE);
    }
    status = mbedtls_to_psa_error(ret);

exit:
    if (status == PSA_SUCCESS) {
        *hash_length = actual_hash_length;
        return (psa_hash_abort(operation));
    } else {
        psa_hash_abort(operation);
        return (status);
    }
}

psa_status_t psa_hash_verify(psa_hash_operation_t *operation,
                             const uint8_t *hash,
                             size_t hash_length) {
    uint8_t actual_hash[MBEDTLS_MD_MAX_SIZE];
    size_t actual_hash_length;
    psa_status_t status = psa_hash_finish(operation,
                                          actual_hash, sizeof(actual_hash),
                                          &actual_hash_length);
    if (status != PSA_SUCCESS)
        return (status);
    if (actual_hash_length != hash_length)
        return (PSA_ERROR_INVALID_SIGNATURE);
    if (safer_memcmp(hash, actual_hash, actual_hash_length) != 0)
        return (PSA_ERROR_INVALID_SIGNATURE);
    return (PSA_SUCCESS);
}

psa_status_t psa_hash_compute(psa_algorithm_t alg,
                              const uint8_t *input, size_t input_length,
                              uint8_t *hash, size_t hash_size,
                              size_t *hash_length) {
    psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT;
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;

    *hash_length = hash_size;
    status = psa_hash_setup(&operation, alg);
    if (status != PSA_SUCCESS)
        goto exit;
    status = psa_hash_update(&operation, input, input_length);
    if (status != PSA_SUCCESS)
        goto exit;
    status = psa_hash_finish(&operation, hash, hash_size, hash_length);
    if (status != PSA_SUCCESS)
        goto exit;

exit:
    if (status == PSA_SUCCESS)
        status = psa_hash_abort(&operation);
    else
        psa_hash_abort(&operation);
    return (status);
}

psa_status_t psa_hash_compare(psa_algorithm_t alg,
                              const uint8_t *input, size_t input_length,
                              const uint8_t *hash, size_t hash_length) {
    psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT;
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;

    status = psa_hash_setup(&operation, alg);
    if (status != PSA_SUCCESS)
        goto exit;
    status = psa_hash_update(&operation, input, input_length);
    if (status != PSA_SUCCESS)
        goto exit;
    status = psa_hash_verify(&operation, hash, hash_length);
    if (status != PSA_SUCCESS)
        goto exit;

exit:
    if (status == PSA_SUCCESS)
        status = psa_hash_abort(&operation);
    else
        psa_hash_abort(&operation);
    return (status);
}

psa_status_t psa_hash_clone(const psa_hash_operation_t *source_operation,
                            psa_hash_operation_t *target_operation) {
    if (target_operation->alg != 0)
        return (PSA_ERROR_BAD_STATE);

    switch (source_operation->alg) {
        case 0:
            return (PSA_ERROR_BAD_STATE);
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD2)
        case PSA_ALG_MD2:
            mbedtls_md2_clone(&target_operation->ctx.md2,
                              &source_operation->ctx.md2);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD4)
        case PSA_ALG_MD4:
            mbedtls_md4_clone(&target_operation->ctx.md4,
                              &source_operation->ctx.md4);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_MD5)
        case PSA_ALG_MD5:
            mbedtls_md5_clone(&target_operation->ctx.md5,
                              &source_operation->ctx.md5);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RIPEMD160)
        case PSA_ALG_RIPEMD160:
            mbedtls_ripemd160_clone(&target_operation->ctx.ripemd160,
                                    &source_operation->ctx.ripemd160);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_1)
        case PSA_ALG_SHA_1:
            mbedtls_sha1_clone(&target_operation->ctx.sha1,
                               &source_operation->ctx.sha1);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_224)
        case PSA_ALG_SHA_224:
            mbedtls_sha256_clone(&target_operation->ctx.sha256,
                                 &source_operation->ctx.sha256);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_256)
        case PSA_ALG_SHA_256:
            mbedtls_sha256_clone(&target_operation->ctx.sha256,
                                 &source_operation->ctx.sha256);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_384)
        case PSA_ALG_SHA_384:
            mbedtls_sha512_clone(&target_operation->ctx.sha512,
                                 &source_operation->ctx.sha512);
            break;
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_SHA_512)
        case PSA_ALG_SHA_512:
            mbedtls_sha512_clone(&target_operation->ctx.sha512,
                                 &source_operation->ctx.sha512);
            break;
#endif
        default:
            return (PSA_ERROR_NOT_SUPPORTED);
    }

    target_operation->alg = source_operation->alg;
    return (PSA_SUCCESS);
}


/****************************************************************/
/* MAC */
/****************************************************************/

static const mbedtls_cipher_info_t *mbedtls_cipher_info_from_psa(
    psa_algorithm_t alg,
    psa_key_type_t key_type,
    size_t key_bits,
    mbedtls_cipher_id_t *cipher_id) {
    mbedtls_cipher_mode_t mode;
    mbedtls_cipher_id_t cipher_id_tmp;

    if (PSA_ALG_IS_AEAD(alg))
        alg = PSA_ALG_AEAD_WITH_SHORTENED_TAG(alg, 0);

    if (PSA_ALG_IS_CIPHER(alg) || PSA_ALG_IS_AEAD(alg)) {
        switch (alg) {
            case PSA_ALG_STREAM_CIPHER:
                mode = MBEDTLS_MODE_STREAM;
                break;
            case PSA_ALG_CTR:
                mode = MBEDTLS_MODE_CTR;
                break;
            case PSA_ALG_CFB:
                mode = MBEDTLS_MODE_CFB;
                break;
            case PSA_ALG_OFB:
                mode = MBEDTLS_MODE_OFB;
                break;
            case PSA_ALG_ECB_NO_PADDING:
                mode = MBEDTLS_MODE_ECB;
                break;
            case PSA_ALG_CBC_NO_PADDING:
                mode = MBEDTLS_MODE_CBC;
                break;
            case PSA_ALG_CBC_PKCS7:
                mode = MBEDTLS_MODE_CBC;
                break;
            case PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, 0):
                mode = MBEDTLS_MODE_CCM;
                break;
            case PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_GCM, 0):
                mode = MBEDTLS_MODE_GCM;
                break;
            case PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CHACHA20_POLY1305, 0):
                mode = MBEDTLS_MODE_CHACHAPOLY;
                break;
            default:
                return (NULL);
        }
    } else if (alg == PSA_ALG_CMAC)
        mode = MBEDTLS_MODE_ECB;
    else
        return (NULL);

    switch (key_type) {
        case PSA_KEY_TYPE_AES:
            cipher_id_tmp = MBEDTLS_CIPHER_ID_AES;
            break;
        case PSA_KEY_TYPE_DES:
            /* key_bits is 64 for Single-DES, 128 for two-key Triple-DES,
             * and 192 for three-key Triple-DES. */
            if (key_bits == 64)
                cipher_id_tmp = MBEDTLS_CIPHER_ID_DES;
            else
                cipher_id_tmp = MBEDTLS_CIPHER_ID_3DES;
            /* mbedtls doesn't recognize two-key Triple-DES as an algorithm,
             * but two-key Triple-DES is functionally three-key Triple-DES
             * with K1=K3, so that's how we present it to mbedtls. */
            if (key_bits == 128)
                key_bits = 192;
            break;
        case PSA_KEY_TYPE_CAMELLIA:
            cipher_id_tmp = MBEDTLS_CIPHER_ID_CAMELLIA;
            break;
        case PSA_KEY_TYPE_ARC4:
            cipher_id_tmp = MBEDTLS_CIPHER_ID_ARC4;
            break;
        case PSA_KEY_TYPE_CHACHA20:
            cipher_id_tmp = MBEDTLS_CIPHER_ID_CHACHA20;
            break;
        default:
            return (NULL);
    }
    if (cipher_id != NULL)
        *cipher_id = cipher_id_tmp;

    return (mbedtls_cipher_info_from_values(cipher_id_tmp,
                                            (int) key_bits, mode));
}

#if defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC)
static size_t psa_get_hash_block_size(psa_algorithm_t alg) {
    switch (alg) {
        case PSA_ALG_MD2:
            return (16);
        case PSA_ALG_MD4:
            return (64);
        case PSA_ALG_MD5:
            return (64);
        case PSA_ALG_RIPEMD160:
            return (64);
        case PSA_ALG_SHA_1:
            return (64);
        case PSA_ALG_SHA_224:
            return (64);
        case PSA_ALG_SHA_256:
            return (64);
        case PSA_ALG_SHA_384:
            return (128);
        case PSA_ALG_SHA_512:
            return (128);
        default:
            return (0);
    }
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC) */

/* Initialize the MAC operation structure. Once this function has been
 * called, psa_mac_abort can run and will do the right thing. */
static psa_status_t psa_mac_init(psa_mac_operation_t *operation,
                                 psa_algorithm_t alg) {
    psa_status_t status = PSA_ERROR_NOT_SUPPORTED;

    operation->alg = PSA_ALG_FULL_LENGTH_MAC(alg);
    operation->key_set = 0;
    operation->iv_set = 0;
    operation->iv_required = 0;
    operation->has_input = 0;
    operation->is_sign = 0;

#if defined(MBEDTLS_CMAC_C)
    if (operation->alg == PSA_ALG_CMAC) {
        operation->iv_required = 0;
        mbedtls_cipher_init(&operation->ctx.cmac);
        status = PSA_SUCCESS;
    } else
#endif /* MBEDTLS_CMAC_C */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC)
        if (PSA_ALG_IS_HMAC(operation->alg)) {
            /* We'll set up the hash operation later in psa_hmac_setup_internal. */
            operation->ctx.hmac.hash_ctx.alg = 0;
            status = PSA_SUCCESS;
        } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HMAC */
        {
            if (! PSA_ALG_IS_MAC(alg))
                status = PSA_ERROR_INVALID_ARGUMENT;
        }

    if (status != PSA_SUCCESS)
        memset(operation, 0, sizeof(*operation));
    return (status);
}

#if defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC)
static psa_status_t psa_hmac_abort_internal(psa_hmac_internal_data *hmac) {
    mbedtls_platform_zeroize(hmac->opad, sizeof(hmac->opad));
    return (psa_hash_abort(&hmac->hash_ctx));
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HMAC */

psa_status_t psa_mac_abort(psa_mac_operation_t *operation) {
    if (operation->alg == 0) {
        /* The object has (apparently) been initialized but it is not
         * in use. It's ok to call abort on such an object, and there's
         * nothing to do. */
        return (PSA_SUCCESS);
    } else
#if defined(MBEDTLS_CMAC_C)
        if (operation->alg == PSA_ALG_CMAC) {
            mbedtls_cipher_free(&operation->ctx.cmac);
        } else
#endif /* MBEDTLS_CMAC_C */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC)
            if (PSA_ALG_IS_HMAC(operation->alg)) {
                psa_hmac_abort_internal(&operation->ctx.hmac);
            } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HMAC */
            {
                /* Sanity check (shouldn't happen: operation->alg should
                 * always have been initialized to a valid value). */
                goto bad_state;
            }

    operation->alg = 0;
    operation->key_set = 0;
    operation->iv_set = 0;
    operation->iv_required = 0;
    operation->has_input = 0;
    operation->is_sign = 0;

    return (PSA_SUCCESS);

bad_state:
    /* If abort is called on an uninitialized object, we can't trust
     * anything. Wipe the object in case it contains confidential data.
     * This may result in a memory leak if a pointer gets overwritten,
     * but it's too late to do anything about this. */
    memset(operation, 0, sizeof(*operation));
    return (PSA_ERROR_BAD_STATE);
}

#if defined(MBEDTLS_CMAC_C)
static psa_status_t psa_cmac_setup(psa_mac_operation_t *operation,
                                   psa_key_slot_t *slot) {
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    const mbedtls_cipher_info_t *cipher_info =
        mbedtls_cipher_info_from_psa(PSA_ALG_CMAC,
                                     slot->attr.type, slot->attr.bits,
                                     NULL);
    if (cipher_info == NULL)
        return (PSA_ERROR_NOT_SUPPORTED);

    ret = mbedtls_cipher_setup(&operation->ctx.cmac, cipher_info);
    if (ret != 0)
        goto exit;

    ret = mbedtls_cipher_cmac_starts(&operation->ctx.cmac,
                                     slot->key.data,
                                     slot->attr.bits);
exit:
    return (mbedtls_to_psa_error(ret));
}
#endif /* MBEDTLS_CMAC_C */

#if defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC)
static psa_status_t psa_hmac_setup_internal(psa_hmac_internal_data *hmac,
                                            const uint8_t *key,
                                            size_t key_length,
                                            psa_algorithm_t hash_alg) {
    uint8_t ipad[PSA_HMAC_MAX_HASH_BLOCK_SIZE];
    size_t i;
    size_t hash_size = PSA_HASH_LENGTH(hash_alg);
    size_t block_size = psa_get_hash_block_size(hash_alg);
    psa_status_t status;

    /* Sanity checks on block_size, to guarantee that there won't be a buffer
     * overflow below. This should never trigger if the hash algorithm
     * is implemented correctly. */
    /* The size checks against the ipad and opad buffers cannot be written
     * `block_size > sizeof( ipad ) || block_size > sizeof( hmac->opad )`
     * because that triggers -Wlogical-op on GCC 7.3. */
    if (block_size > sizeof(ipad))
        return (PSA_ERROR_NOT_SUPPORTED);
    if (block_size > sizeof(hmac->opad))
        return (PSA_ERROR_NOT_SUPPORTED);
    if (block_size < hash_size)
        return (PSA_ERROR_NOT_SUPPORTED);

    if (key_length > block_size) {
        status = psa_hash_compute(hash_alg, key, key_length,
                                  ipad, sizeof(ipad), &key_length);
        if (status != PSA_SUCCESS)
            goto cleanup;
    }
    /* A 0-length key is not commonly used in HMAC when used as a MAC,
     * but it is permitted. It is common when HMAC is used in HKDF, for
     * example. Don't call `memcpy` in the 0-length because `key` could be
     * an invalid pointer which would make the behavior undefined. */
    else if (key_length != 0)
        memcpy(ipad, key, key_length);

    /* ipad contains the key followed by garbage. Xor and fill with 0x36
     * to create the ipad value. */
    for (i = 0; i < key_length; i++)
        ipad[i] ^= 0x36;
    memset(ipad + key_length, 0x36, block_size - key_length);

    /* Copy the key material from ipad to opad, flipping the requisite bits,
     * and filling the rest of opad with the requisite constant. */
    for (i = 0; i < key_length; i++)
        hmac->opad[i] = ipad[i] ^ 0x36 ^ 0x5C;
    memset(hmac->opad + key_length, 0x5C, block_size - key_length);

    status = psa_hash_setup(&hmac->hash_ctx, hash_alg);
    if (status != PSA_SUCCESS)
        goto cleanup;

    status = psa_hash_update(&hmac->hash_ctx, ipad, block_size);

cleanup:
    mbedtls_platform_zeroize(ipad, sizeof(ipad));

    return (status);
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HMAC */

static psa_status_t psa_mac_setup(psa_mac_operation_t *operation,
                                  mbedtls_svc_key_id_t key,
                                  psa_algorithm_t alg,
                                  int is_sign) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;
    psa_key_usage_t usage =
        is_sign ? PSA_KEY_USAGE_SIGN_HASH : PSA_KEY_USAGE_VERIFY_HASH;

    /* A context must be freshly initialized before it can be set up. */
    if (operation->alg != 0) {
        return (PSA_ERROR_BAD_STATE);
    }

    status = psa_mac_init(operation, alg);
    if (status != PSA_SUCCESS)
        return (status);
    if (is_sign)
        operation->is_sign = 1;

    status = psa_get_and_lock_transparent_key_slot_with_policy(
                 key, &slot, usage, alg);
    if (status != PSA_SUCCESS)
        goto exit;

    /* Validate the combination of key type and algorithm */
    status = psa_mac_key_can_do(alg, slot->attr.type);
    if (status != PSA_SUCCESS)
        goto exit;

    /* Get the output length for the algorithm and key combination. None of the
     * currently supported algorithms have an output length dependent on actual
     * key size, so setting it to a bogus value is currently OK. */
    operation->mac_size = PSA_MAC_LENGTH(slot->attr.type, 0, alg);

    if (operation->mac_size < 4) {
        /* A very short MAC is too short for security since it can be
         * brute-forced. Ancient protocols with 32-bit MACs do exist,
         * so we make this our minimum, even though 32 bits is still
         * too small for security. */
        status = PSA_ERROR_NOT_SUPPORTED;
        goto exit;
    }

    if (operation->mac_size >
            PSA_MAC_LENGTH(slot->attr.type, 0, PSA_ALG_FULL_LENGTH_MAC(alg))) {
        /* It's impossible to "truncate" to a larger length than the full length
         * of the algorithm. */
        status = PSA_ERROR_INVALID_ARGUMENT;
        goto exit;
    }

#if defined(MBEDTLS_CMAC_C)
    if (PSA_ALG_FULL_LENGTH_MAC(alg) == PSA_ALG_CMAC) {
        status = psa_cmac_setup(operation, slot);
    } else
#endif /* MBEDTLS_CMAC_C */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC)
        if (PSA_ALG_IS_HMAC(alg)) {
            /* Sanity check. This shouldn't fail on a valid configuration. */
            if (operation->mac_size > sizeof(operation->ctx.hmac.opad)) {
                status = PSA_ERROR_NOT_SUPPORTED;
                goto exit;
            }

            if (slot->attr.type != PSA_KEY_TYPE_HMAC) {
                status = PSA_ERROR_INVALID_ARGUMENT;
                goto exit;
            }

            status = psa_hmac_setup_internal(&operation->ctx.hmac,
                                             slot->key.data,
                                             slot->key.bytes,
                                             PSA_ALG_HMAC_GET_HASH(alg));
        } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HMAC */
        {
            status = PSA_ERROR_NOT_SUPPORTED;
        }

exit:
    if (status != PSA_SUCCESS) {
        psa_mac_abort(operation);
    } else {
        operation->key_set = 1;
    }

    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}

psa_status_t psa_mac_sign_setup(psa_mac_operation_t *operation,
                                mbedtls_svc_key_id_t key,
                                psa_algorithm_t alg) {
    return (psa_mac_setup(operation, key, alg, 1));
}

psa_status_t psa_mac_verify_setup(psa_mac_operation_t *operation,
                                  mbedtls_svc_key_id_t key,
                                  psa_algorithm_t alg) {
    return (psa_mac_setup(operation, key, alg, 0));
}

psa_status_t psa_mac_update(psa_mac_operation_t *operation,
                            const uint8_t *input,
                            size_t input_length) {
    psa_status_t status = PSA_ERROR_BAD_STATE;
    if (! operation->key_set)
        return (PSA_ERROR_BAD_STATE);
    if (operation->iv_required && ! operation->iv_set)
        return (PSA_ERROR_BAD_STATE);
    operation->has_input = 1;

#if defined(MBEDTLS_CMAC_C)
    if (operation->alg == PSA_ALG_CMAC) {
        int ret = mbedtls_cipher_cmac_update(&operation->ctx.cmac,
                                             input, input_length);
        status = mbedtls_to_psa_error(ret);
    } else
#endif /* MBEDTLS_CMAC_C */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC)
        if (PSA_ALG_IS_HMAC(operation->alg)) {
            status = psa_hash_update(&operation->ctx.hmac.hash_ctx, input,
                                     input_length);
        } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HMAC */
        {
            /* This shouldn't happen if `operation` was initialized by
             * a setup function. */
            return (PSA_ERROR_BAD_STATE);
        }

    if (status != PSA_SUCCESS)
        psa_mac_abort(operation);
    return (status);
}

#if defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC)
static psa_status_t psa_hmac_finish_internal(psa_hmac_internal_data *hmac,
                                             uint8_t *mac,
                                             size_t mac_size) {
    uint8_t tmp[MBEDTLS_MD_MAX_SIZE];
    psa_algorithm_t hash_alg = hmac->hash_ctx.alg;
    size_t hash_size = 0;
    size_t block_size = psa_get_hash_block_size(hash_alg);
    psa_status_t status;

    status = psa_hash_finish(&hmac->hash_ctx, tmp, sizeof(tmp), &hash_size);
    if (status != PSA_SUCCESS)
        return (status);
    /* From here on, tmp needs to be wiped. */

    status = psa_hash_setup(&hmac->hash_ctx, hash_alg);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_hash_update(&hmac->hash_ctx, hmac->opad, block_size);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_hash_update(&hmac->hash_ctx, tmp, hash_size);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_hash_finish(&hmac->hash_ctx, tmp, sizeof(tmp), &hash_size);
    if (status != PSA_SUCCESS)
        goto exit;

    memcpy(mac, tmp, mac_size);

exit:
    mbedtls_platform_zeroize(tmp, hash_size);
    return (status);
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HMAC */

static psa_status_t psa_mac_finish_internal(psa_mac_operation_t *operation,
                                            uint8_t *mac,
                                            size_t mac_size) {
    if (! operation->key_set)
        return (PSA_ERROR_BAD_STATE);
    if (operation->iv_required && ! operation->iv_set)
        return (PSA_ERROR_BAD_STATE);

    if (mac_size < operation->mac_size)
        return (PSA_ERROR_BUFFER_TOO_SMALL);

#if defined(MBEDTLS_CMAC_C)
    if (operation->alg == PSA_ALG_CMAC) {
        uint8_t tmp[PSA_BLOCK_CIPHER_BLOCK_MAX_SIZE];
        int ret = mbedtls_cipher_cmac_finish(&operation->ctx.cmac, tmp);
        if (ret == 0)
            memcpy(mac, tmp, operation->mac_size);
        mbedtls_platform_zeroize(tmp, sizeof(tmp));
        return (mbedtls_to_psa_error(ret));
    } else
#endif /* MBEDTLS_CMAC_C */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_HMAC)
        if (PSA_ALG_IS_HMAC(operation->alg)) {
            return (psa_hmac_finish_internal(&operation->ctx.hmac,
                                             mac, operation->mac_size));
        } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HMAC */
        {
            /* This shouldn't happen if `operation` was initialized by
             * a setup function. */
            return (PSA_ERROR_BAD_STATE);
        }
}

psa_status_t psa_mac_sign_finish(psa_mac_operation_t *operation,
                                 uint8_t *mac,
                                 size_t mac_size,
                                 size_t *mac_length) {
    psa_status_t status;

    if (operation->alg == 0) {
        return (PSA_ERROR_BAD_STATE);
    }

    /* Fill the output buffer with something that isn't a valid mac
     * (barring an attack on the mac and deliberately-crafted input),
     * in case the caller doesn't check the return status properly. */
    *mac_length = mac_size;
    /* If mac_size is 0 then mac may be NULL and then the
     * call to memset would have undefined behavior. */
    if (mac_size != 0)
        memset(mac, '!', mac_size);

    if (! operation->is_sign) {
        return (PSA_ERROR_BAD_STATE);
    }

    status = psa_mac_finish_internal(operation, mac, mac_size);

    if (status == PSA_SUCCESS) {
        status = psa_mac_abort(operation);
        if (status == PSA_SUCCESS)
            *mac_length = operation->mac_size;
        else
            memset(mac, '!', mac_size);
    } else
        psa_mac_abort(operation);
    return (status);
}

psa_status_t psa_mac_verify_finish(psa_mac_operation_t *operation,
                                   const uint8_t *mac,
                                   size_t mac_length) {
    uint8_t actual_mac[PSA_MAC_MAX_SIZE];
    psa_status_t status;

    if (operation->alg == 0) {
        return (PSA_ERROR_BAD_STATE);
    }

    if (operation->is_sign) {
        return (PSA_ERROR_BAD_STATE);
    }
    if (operation->mac_size != mac_length) {
        status = PSA_ERROR_INVALID_SIGNATURE;
        goto cleanup;
    }

    status = psa_mac_finish_internal(operation,
                                     actual_mac, sizeof(actual_mac));
    if (status != PSA_SUCCESS)
        goto cleanup;

    if (safer_memcmp(mac, actual_mac, mac_length) != 0)
        status = PSA_ERROR_INVALID_SIGNATURE;

cleanup:
    if (status == PSA_SUCCESS)
        status = psa_mac_abort(operation);
    else
        psa_mac_abort(operation);

    mbedtls_platform_zeroize(actual_mac, sizeof(actual_mac));

    return (status);
}



/****************************************************************/
/* Asymmetric cryptography */
/****************************************************************/

psa_status_t psa_sign_hash_internal(
    const psa_key_attributes_t *attributes,
    const uint8_t *key_buffer, size_t key_buffer_size,
    psa_algorithm_t alg, const uint8_t *hash, size_t hash_length,
    uint8_t *signature, size_t signature_size, size_t *signature_length) {
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS)
    if (attributes->core.type == PSA_KEY_TYPE_RSA_KEY_PAIR) {
        return (mbedtls_psa_rsa_sign_hash(
                    attributes,
                    key_buffer, key_buffer_size,
                    alg, hash, hash_length,
                    signature, signature_size, signature_length));
    } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS) */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA)
        if (PSA_KEY_TYPE_IS_ECC(attributes->core.type)) {
            if (PSA_ALG_IS_ECDSA(alg)) {
                return (mbedtls_psa_ecdsa_sign_hash(
                            attributes,
                            key_buffer, key_buffer_size,
                            alg, hash, hash_length,
                            signature, signature_size, signature_length));
            } else {
                return (PSA_ERROR_INVALID_ARGUMENT);
            }
        } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA) */
        {
            (void)attributes;
            (void)key_buffer;
            (void)key_buffer_size;
            (void)alg;
            (void)hash;
            (void)hash_length;
            (void)signature;
            (void)signature_size;
            (void)signature_length;

            return (PSA_ERROR_NOT_SUPPORTED);
        }
}

psa_status_t psa_sign_hash(mbedtls_svc_key_id_t key,
                           psa_algorithm_t alg,
                           const uint8_t *hash,
                           size_t hash_length,
                           uint8_t *signature,
                           size_t signature_size,
                           size_t *signature_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    *signature_length = signature_size;
    /* Immediately reject a zero-length signature buffer. This guarantees
     * that signature must be a valid pointer. (On the other hand, the hash
     * buffer can in principle be empty since it doesn't actually have
     * to be a hash.) */
    if (signature_size == 0)
        return (PSA_ERROR_BUFFER_TOO_SMALL);

    status = psa_get_and_lock_key_slot_with_policy(key, &slot,
                                                   PSA_KEY_USAGE_SIGN_HASH,
                                                   alg);
    if (status != PSA_SUCCESS)
        goto exit;
    if (! PSA_KEY_TYPE_IS_KEY_PAIR(slot->attr.type)) {
        status = PSA_ERROR_INVALID_ARGUMENT;
        goto exit;
    }

    psa_key_attributes_t attributes = {
        .core = slot->attr
    };

    status = psa_driver_wrapper_sign_hash(
                 &attributes, slot->key.data, slot->key.bytes,
                 alg, hash, hash_length,
                 signature, signature_size, signature_length);

exit:
    /* Fill the unused part of the output buffer (the whole buffer on error,
     * the trailing part on success) with something that isn't a valid mac
     * (barring an attack on the mac and deliberately-crafted input),
     * in case the caller doesn't check the return status properly. */
    if (status == PSA_SUCCESS)
        memset(signature + *signature_length, '!',
               signature_size - *signature_length);
    else
        memset(signature, '!', signature_size);
    /* If signature_size is 0 then we have nothing to do. We must not call
     * memset because signature may be NULL in this case. */

    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}

psa_status_t psa_verify_hash_internal(
    const psa_key_attributes_t *attributes,
    const uint8_t *key_buffer, size_t key_buffer_size,
    psa_algorithm_t alg, const uint8_t *hash, size_t hash_length,
    const uint8_t *signature, size_t signature_length) {
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS)
    if (PSA_KEY_TYPE_IS_RSA(attributes->core.type)) {
        return (mbedtls_psa_rsa_verify_hash(
                    attributes,
                    key_buffer, key_buffer_size,
                    alg, hash, hash_length,
                    signature, signature_length));
    } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_SIGN) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PSS) */
        if (PSA_KEY_TYPE_IS_ECC(attributes->core.type)) {
#if defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA)
            if (PSA_ALG_IS_ECDSA(alg)) {
                return (mbedtls_psa_ecdsa_verify_hash(
                            attributes,
                            key_buffer, key_buffer_size,
                            alg, hash, hash_length,
                            signature, signature_length));
            } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA) */
            {
                return (PSA_ERROR_INVALID_ARGUMENT);
            }
        } else {
            (void)key_buffer;
            (void)key_buffer_size;
            (void)alg;
            (void)hash;
            (void)hash_length;
            (void)signature;
            (void)signature_length;

            return (PSA_ERROR_NOT_SUPPORTED);
        }
}

psa_status_t psa_verify_hash(mbedtls_svc_key_id_t key,
                             psa_algorithm_t alg,
                             const uint8_t *hash,
                             size_t hash_length,
                             const uint8_t *signature,
                             size_t signature_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    status = psa_get_and_lock_key_slot_with_policy(key, &slot,
                                                   PSA_KEY_USAGE_VERIFY_HASH,
                                                   alg);
    if (status != PSA_SUCCESS)
        return (status);

    psa_key_attributes_t attributes = {
        .core = slot->attr
    };

    status = psa_driver_wrapper_verify_hash(
                 &attributes, slot->key.data, slot->key.bytes,
                 alg, hash, hash_length,
                 signature, signature_length);

    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}

#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP)
static void psa_rsa_oaep_set_padding_mode(psa_algorithm_t alg,
                                          mbedtls_rsa_context *rsa) {
    psa_algorithm_t hash_alg = PSA_ALG_RSA_OAEP_GET_HASH(alg);
    const mbedtls_md_info_t *md_info = mbedtls_md_info_from_psa(hash_alg);
    mbedtls_md_type_t md_alg = mbedtls_md_get_type(md_info);
    mbedtls_rsa_set_padding(rsa, MBEDTLS_RSA_PKCS_V21, md_alg);
}
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP) */

psa_status_t psa_asymmetric_encrypt(mbedtls_svc_key_id_t key,
                                    psa_algorithm_t alg,
                                    const uint8_t *input,
                                    size_t input_length,
                                    const uint8_t *salt,
                                    size_t salt_length,
                                    uint8_t *output,
                                    size_t output_size,
                                    size_t *output_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    (void) input;
    (void) input_length;
    (void) salt;
    (void) output;
    (void) output_size;

    *output_length = 0;

    if (! PSA_ALG_IS_RSA_OAEP(alg) && salt_length != 0)
        return (PSA_ERROR_INVALID_ARGUMENT);

    status = psa_get_and_lock_transparent_key_slot_with_policy(
                 key, &slot, PSA_KEY_USAGE_ENCRYPT, alg);
    if (status != PSA_SUCCESS)
        return (status);
    if (!(PSA_KEY_TYPE_IS_PUBLIC_KEY(slot->attr.type) ||
            PSA_KEY_TYPE_IS_KEY_PAIR(slot->attr.type))) {
        status = PSA_ERROR_INVALID_ARGUMENT;
        goto exit;
    }

#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP)
    if (PSA_KEY_TYPE_IS_RSA(slot->attr.type)) {
        mbedtls_rsa_context *rsa = NULL;
        status = mbedtls_psa_rsa_load_representation(slot->attr.type,
                                                     slot->key.data,
                                                     slot->key.bytes,
                                                     &rsa);
        if (status != PSA_SUCCESS)
            goto rsa_exit;

        if (output_size < mbedtls_rsa_get_len(rsa)) {
            status = PSA_ERROR_BUFFER_TOO_SMALL;
            goto rsa_exit;
        }
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT)
        if (alg == PSA_ALG_RSA_PKCS1V15_CRYPT) {
            status = mbedtls_to_psa_error(
                         mbedtls_rsa_pkcs1_encrypt(rsa,
                                                   mbedtls_psa_get_random,
                                                   MBEDTLS_PSA_RANDOM_STATE,
                                                   MBEDTLS_RSA_PUBLIC,
                                                   input_length,
                                                   input,
                                                   output));
        } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP)
            if (PSA_ALG_IS_RSA_OAEP(alg)) {
                psa_rsa_oaep_set_padding_mode(alg, rsa);
                status = mbedtls_to_psa_error(
                             mbedtls_rsa_rsaes_oaep_encrypt(rsa,
                                                            mbedtls_psa_get_random,
                                                            MBEDTLS_PSA_RANDOM_STATE,
                                                            MBEDTLS_RSA_PUBLIC,
                                                            salt, salt_length,
                                                            input_length,
                                                            input,
                                                            output));
            } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP */
            {
                status = PSA_ERROR_INVALID_ARGUMENT;
                goto rsa_exit;
            }
rsa_exit:
        if (status == PSA_SUCCESS)
            *output_length = mbedtls_rsa_get_len(rsa);

        mbedtls_rsa_free(rsa);
        mbedtls_free(rsa);
    } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP) */
    {
        status = PSA_ERROR_NOT_SUPPORTED;
    }

exit:
    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}

psa_status_t psa_asymmetric_decrypt(mbedtls_svc_key_id_t key,
                                    psa_algorithm_t alg,
                                    const uint8_t *input,
                                    size_t input_length,
                                    const uint8_t *salt,
                                    size_t salt_length,
                                    uint8_t *output,
                                    size_t output_size,
                                    size_t *output_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    (void) input;
    (void) input_length;
    (void) salt;
    (void) output;
    (void) output_size;

    *output_length = 0;

    if (! PSA_ALG_IS_RSA_OAEP(alg) && salt_length != 0)
        return (PSA_ERROR_INVALID_ARGUMENT);

    status = psa_get_and_lock_transparent_key_slot_with_policy(
                 key, &slot, PSA_KEY_USAGE_DECRYPT, alg);
    if (status != PSA_SUCCESS)
        return (status);
    if (! PSA_KEY_TYPE_IS_KEY_PAIR(slot->attr.type)) {
        status = PSA_ERROR_INVALID_ARGUMENT;
        goto exit;
    }

#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP)
    if (slot->attr.type == PSA_KEY_TYPE_RSA_KEY_PAIR) {
        mbedtls_rsa_context *rsa = NULL;
        status = mbedtls_psa_rsa_load_representation(slot->attr.type,
                                                     slot->key.data,
                                                     slot->key.bytes,
                                                     &rsa);
        if (status != PSA_SUCCESS)
            goto exit;

        if (input_length != mbedtls_rsa_get_len(rsa)) {
            status = PSA_ERROR_INVALID_ARGUMENT;
            goto rsa_exit;
        }

#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT)
        if (alg == PSA_ALG_RSA_PKCS1V15_CRYPT) {
            status = mbedtls_to_psa_error(
                         mbedtls_rsa_pkcs1_decrypt(rsa,
                                                   mbedtls_psa_get_random,
                                                   MBEDTLS_PSA_RANDOM_STATE,
                                                   MBEDTLS_RSA_PRIVATE,
                                                   output_length,
                                                   input,
                                                   output,
                                                   output_size));
        } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP)
            if (PSA_ALG_IS_RSA_OAEP(alg)) {
                psa_rsa_oaep_set_padding_mode(alg, rsa);
                status = mbedtls_to_psa_error(
                             mbedtls_rsa_rsaes_oaep_decrypt(rsa,
                                                            mbedtls_psa_get_random,
                                                            MBEDTLS_PSA_RANDOM_STATE,
                                                            MBEDTLS_RSA_PRIVATE,
                                                            salt, salt_length,
                                                            output_length,
                                                            input,
                                                            output,
                                                            output_size));
            } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP */
            {
                status = PSA_ERROR_INVALID_ARGUMENT;
            }

rsa_exit:
        mbedtls_rsa_free(rsa);
        mbedtls_free(rsa);
    } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_PKCS1V15_CRYPT) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_RSA_OAEP) */
    {
        status = PSA_ERROR_NOT_SUPPORTED;
    }

exit:
    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}



/****************************************************************/
/* Symmetric cryptography */
/****************************************************************/

static psa_status_t psa_cipher_setup(psa_cipher_operation_t *operation,
                                     mbedtls_svc_key_id_t key,
                                     psa_algorithm_t alg,
                                     mbedtls_operation_t cipher_operation) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    int ret = 0;
    psa_key_slot_t *slot;
    size_t key_bits;
    const mbedtls_cipher_info_t *cipher_info = NULL;
    psa_key_usage_t usage = (cipher_operation == MBEDTLS_ENCRYPT ?
                             PSA_KEY_USAGE_ENCRYPT :
                             PSA_KEY_USAGE_DECRYPT);

    /* A context must be freshly initialized before it can be set up. */
    if (operation->alg != 0)
        return (PSA_ERROR_BAD_STATE);

    /* The requested algorithm must be one that can be processed by cipher. */
    if (! PSA_ALG_IS_CIPHER(alg))
        return (PSA_ERROR_INVALID_ARGUMENT);

    /* Fetch key material from key storage. */
    status = psa_get_and_lock_key_slot_with_policy(key, &slot, usage, alg);
    if (status != PSA_SUCCESS)
        goto exit;

    /* Initialize the operation struct members, except for alg. The alg member
     * is used to indicate to psa_cipher_abort that there are resources to free,
     * so we only set it after resources have been allocated/initialized. */
    operation->key_set = 0;
    operation->iv_set = 0;
    operation->mbedtls_in_use = 0;
    operation->iv_size = 0;
    operation->block_size = 0;
    if (alg == PSA_ALG_ECB_NO_PADDING)
        operation->iv_required = 0;
    else
        operation->iv_required = 1;

    /* Try doing the operation through a driver before using software fallback. */
    if (cipher_operation == MBEDTLS_ENCRYPT)
        status = psa_driver_wrapper_cipher_encrypt_setup(&operation->ctx.driver,
                                                         slot,
                                                         alg);
    else
        status = psa_driver_wrapper_cipher_decrypt_setup(&operation->ctx.driver,
                                                         slot,
                                                         alg);

    if (status == PSA_SUCCESS) {
        /* Once the driver context is initialised, it needs to be freed using
        * psa_cipher_abort. Indicate this through setting alg. */
        operation->alg = alg;
    }

    if (status != PSA_ERROR_NOT_SUPPORTED ||
            psa_key_lifetime_is_external(slot->attr.lifetime))
        goto exit;

    /* Proceed with initializing an mbed TLS cipher context if no driver is
     * available for the given algorithm & key. */
    mbedtls_cipher_init(&operation->ctx.cipher);

    /* Once the cipher context is initialised, it needs to be freed using
     * psa_cipher_abort. Indicate there is something to be freed through setting
     * alg, and indicate the operation is being done using mbedtls crypto through
     * setting mbedtls_in_use. */
    operation->alg = alg;
    operation->mbedtls_in_use = 1;

    key_bits = psa_get_key_slot_bits(slot);
    cipher_info = mbedtls_cipher_info_from_psa(alg, slot->attr.type, key_bits, NULL);
    if (cipher_info == NULL) {
        status = PSA_ERROR_NOT_SUPPORTED;
        goto exit;
    }

    ret = mbedtls_cipher_setup(&operation->ctx.cipher, cipher_info);
    if (ret != 0)
        goto exit;

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES)
    if (slot->attr.type == PSA_KEY_TYPE_DES && key_bits == 128) {
        /* Two-key Triple-DES is 3-key Triple-DES with K1=K3 */
        uint8_t keys[24];
        memcpy(keys, slot->key.data, 16);
        memcpy(keys + 16, slot->key.data, 8);
        ret = mbedtls_cipher_setkey(&operation->ctx.cipher,
                                    keys,
                                    192, cipher_operation);
    } else
#endif
    {
        ret = mbedtls_cipher_setkey(&operation->ctx.cipher,
                                    slot->key.data,
                                    (int) key_bits, cipher_operation);
    }
    if (ret != 0)
        goto exit;

#if defined(MBEDTLS_PSA_BUILTIN_ALG_CBC_NO_PADDING) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_CBC_PKCS7)
    switch (alg) {
        case PSA_ALG_CBC_NO_PADDING:
            ret = mbedtls_cipher_set_padding_mode(&operation->ctx.cipher,
                                                  MBEDTLS_PADDING_NONE);
            break;
        case PSA_ALG_CBC_PKCS7:
            ret = mbedtls_cipher_set_padding_mode(&operation->ctx.cipher,
                                                  MBEDTLS_PADDING_PKCS7);
            break;
        default:
            /* The algorithm doesn't involve padding. */
            ret = 0;
            break;
    }
    if (ret != 0)
        goto exit;
#endif /* MBEDTLS_PSA_BUILTIN_ALG_CBC_NO_PADDING || MBEDTLS_PSA_BUILTIN_ALG_CBC_PKCS7 */

    operation->block_size = (PSA_ALG_IS_STREAM_CIPHER(alg) ? 1 :
                             PSA_BLOCK_CIPHER_BLOCK_LENGTH(slot->attr.type));
    if ((alg & PSA_ALG_CIPHER_FROM_BLOCK_FLAG) != 0 &&
            alg != PSA_ALG_ECB_NO_PADDING) {
        operation->iv_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(slot->attr.type);
    }
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_CHACHA20)
    else if (alg == PSA_ALG_STREAM_CIPHER && slot->attr.type == PSA_KEY_TYPE_CHACHA20)
        operation->iv_size = 12;
#endif

    status = PSA_SUCCESS;

exit:
    if (ret != 0)
        status = mbedtls_to_psa_error(ret);
    if (status == PSA_SUCCESS) {
        /* Update operation flags for both driver and software implementations */
        operation->key_set = 1;
    } else
        psa_cipher_abort(operation);

    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}

psa_status_t psa_cipher_encrypt_setup(psa_cipher_operation_t *operation,
                                      mbedtls_svc_key_id_t key,
                                      psa_algorithm_t alg) {
    return (psa_cipher_setup(operation, key, alg, MBEDTLS_ENCRYPT));
}

psa_status_t psa_cipher_decrypt_setup(psa_cipher_operation_t *operation,
                                      mbedtls_svc_key_id_t key,
                                      psa_algorithm_t alg) {
    return (psa_cipher_setup(operation, key, alg, MBEDTLS_DECRYPT));
}

psa_status_t psa_cipher_generate_iv(psa_cipher_operation_t *operation,
                                    uint8_t *iv,
                                    size_t iv_size,
                                    size_t *iv_length) {
    psa_status_t status;
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    if (operation->iv_set || ! operation->iv_required) {
        return (PSA_ERROR_BAD_STATE);
    }

    if (operation->mbedtls_in_use == 0) {
        status = psa_driver_wrapper_cipher_generate_iv(&operation->ctx.driver,
                                                       iv,
                                                       iv_size,
                                                       iv_length);
        goto exit;
    }

    if (iv_size < operation->iv_size) {
        status = PSA_ERROR_BUFFER_TOO_SMALL;
        goto exit;
    }
    ret = mbedtls_psa_get_random(MBEDTLS_PSA_RANDOM_STATE,
                                 iv, operation->iv_size);
    if (ret != 0) {
        status = mbedtls_to_psa_error(ret);
        goto exit;
    }

    *iv_length = operation->iv_size;
    status = psa_cipher_set_iv(operation, iv, *iv_length);

exit:
    if (status == PSA_SUCCESS)
        operation->iv_set = 1;
    else
        psa_cipher_abort(operation);
    return (status);
}

psa_status_t psa_cipher_set_iv(psa_cipher_operation_t *operation,
                               const uint8_t *iv,
                               size_t iv_length) {
    psa_status_t status;
    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
    if (operation->iv_set || ! operation->iv_required) {
        return (PSA_ERROR_BAD_STATE);
    }

    if (operation->mbedtls_in_use == 0) {
        status = psa_driver_wrapper_cipher_set_iv(&operation->ctx.driver,
                                                  iv,
                                                  iv_length);
        goto exit;
    }

    if (iv_length != operation->iv_size) {
        status = PSA_ERROR_INVALID_ARGUMENT;
        goto exit;
    }
    ret = mbedtls_cipher_set_iv(&operation->ctx.cipher, iv, iv_length);
    status = mbedtls_to_psa_error(ret);
exit:
    if (status == PSA_SUCCESS)
        operation->iv_set = 1;
    else
        psa_cipher_abort(operation);
    return (status);
}

/* Process input for which the algorithm is set to ECB mode. This requires
 * manual processing, since the PSA API is defined as being able to process
 * arbitrary-length calls to psa_cipher_update() with ECB mode, but the
 * underlying mbedtls_cipher_update only takes full blocks. */
static psa_status_t psa_cipher_update_ecb_internal(
    mbedtls_cipher_context_t *ctx,
    const uint8_t *input,
    size_t input_length,
    uint8_t *output,
    size_t output_size,
    size_t *output_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    size_t block_size = ctx->cipher_info->block_size;
    size_t internal_output_length = 0;
    *output_length = 0;

    if (input_length == 0) {
        status = PSA_SUCCESS;
        goto exit;
    }

    if (ctx->unprocessed_len > 0) {
        /* Fill up to block size, and run the block if there's a full one. */
        size_t bytes_to_copy = block_size - ctx->unprocessed_len;

        if (input_length < bytes_to_copy)
            bytes_to_copy = input_length;

        memcpy(&(ctx->unprocessed_data[ctx->unprocessed_len]),
               input, bytes_to_copy);
        input_length -= bytes_to_copy;
        input += bytes_to_copy;
        ctx->unprocessed_len += bytes_to_copy;

        if (ctx->unprocessed_len == block_size) {
            status = mbedtls_to_psa_error(
                         mbedtls_cipher_update(ctx,
                                               ctx->unprocessed_data,
                                               block_size,
                                               output, &internal_output_length));

            if (status != PSA_SUCCESS)
                goto exit;

            output += internal_output_length;
            output_size -= internal_output_length;
            *output_length += internal_output_length;
            ctx->unprocessed_len = 0;
        }
    }

    while (input_length >= block_size) {
        /* Run all full blocks we have, one by one */
        status = mbedtls_to_psa_error(
                     mbedtls_cipher_update(ctx, input,
                                           block_size,
                                           output, &internal_output_length));

        if (status != PSA_SUCCESS)
            goto exit;

        input_length -= block_size;
        input += block_size;

        output += internal_output_length;
        output_size -= internal_output_length;
        *output_length += internal_output_length;
    }

    if (input_length > 0) {
        /* Save unprocessed bytes for later processing */
        memcpy(&(ctx->unprocessed_data[ctx->unprocessed_len]),
               input, input_length);
        ctx->unprocessed_len += input_length;
    }

    status = PSA_SUCCESS;

exit:
    return (status);
}

psa_status_t psa_cipher_update(psa_cipher_operation_t *operation,
                               const uint8_t *input,
                               size_t input_length,
                               uint8_t *output,
                               size_t output_size,
                               size_t *output_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    size_t expected_output_size;
    if (operation->alg == 0) {
        return (PSA_ERROR_BAD_STATE);
    }
    if (operation->iv_required && ! operation->iv_set) {
        return (PSA_ERROR_BAD_STATE);
    }

    if (operation->mbedtls_in_use == 0) {
        status = psa_driver_wrapper_cipher_update(&operation->ctx.driver,
                                                  input,
                                                  input_length,
                                                  output,
                                                  output_size,
                                                  output_length);
        goto exit;
    }

    if (! PSA_ALG_IS_STREAM_CIPHER(operation->alg)) {
        /* Take the unprocessed partial block left over from previous
         * update calls, if any, plus the input to this call. Remove
         * the last partial block, if any. You get the data that will be
         * output in this call. */
        expected_output_size =
            (operation->ctx.cipher.unprocessed_len + input_length)
            / operation->block_size * operation->block_size;
    } else {
        expected_output_size = input_length;
    }

    if (output_size < expected_output_size) {
        status = PSA_ERROR_BUFFER_TOO_SMALL;
        goto exit;
    }

    if (operation->alg == PSA_ALG_ECB_NO_PADDING) {
        /* mbedtls_cipher_update has an API inconsistency: it will only
        * process a single block at a time in ECB mode. Abstract away that
        * inconsistency here to match the PSA API behaviour. */
        status = psa_cipher_update_ecb_internal(&operation->ctx.cipher,
                                                input,
                                                input_length,
                                                output,
                                                output_size,
                                                output_length);
    } else {
        status = mbedtls_to_psa_error(
                     mbedtls_cipher_update(&operation->ctx.cipher, input,
                                           input_length, output, output_length));
    }
exit:
    if (status != PSA_SUCCESS)
        psa_cipher_abort(operation);
    return (status);
}

psa_status_t psa_cipher_finish(psa_cipher_operation_t *operation,
                               uint8_t *output,
                               size_t output_size,
                               size_t *output_length) {
    psa_status_t status = PSA_ERROR_GENERIC_ERROR;
    uint8_t temp_output_buffer[MBEDTLS_MAX_BLOCK_LENGTH];
    if (operation->alg == 0) {
        return (PSA_ERROR_BAD_STATE);
    }
    if (operation->iv_required && ! operation->iv_set) {
        return (PSA_ERROR_BAD_STATE);
    }

    if (operation->mbedtls_in_use == 0) {
        status = psa_driver_wrapper_cipher_finish(&operation->ctx.driver,
                                                  output,
                                                  output_size,
                                                  output_length);
        goto exit;
    }

    if (operation->ctx.cipher.unprocessed_len != 0) {
        if (operation->alg == PSA_ALG_ECB_NO_PADDING ||
                operation->alg == PSA_ALG_CBC_NO_PADDING) {
            status = PSA_ERROR_INVALID_ARGUMENT;
            goto exit;
        }
    }

    status = mbedtls_to_psa_error(
                 mbedtls_cipher_finish(&operation->ctx.cipher,
                                       temp_output_buffer,
                                       output_length));
    if (status != PSA_SUCCESS)
        goto exit;

    if (*output_length == 0)
        ; /* Nothing to copy. Note that output may be NULL in this case. */
    else if (output_size >= *output_length)
        memcpy(output, temp_output_buffer, *output_length);
    else
        status = PSA_ERROR_BUFFER_TOO_SMALL;

exit:
    if (operation->mbedtls_in_use == 1)
        mbedtls_platform_zeroize(temp_output_buffer, sizeof(temp_output_buffer));

    if (status == PSA_SUCCESS)
        return (psa_cipher_abort(operation));
    else {
        *output_length = 0;
        (void) psa_cipher_abort(operation);

        return (status);
    }
}

psa_status_t psa_cipher_abort(psa_cipher_operation_t *operation) {
    if (operation->alg == 0) {
        /* The object has (apparently) been initialized but it is not (yet)
         * in use. It's ok to call abort on such an object, and there's
         * nothing to do. */
        return (PSA_SUCCESS);
    }

    /* Sanity check (shouldn't happen: operation->alg should
     * always have been initialized to a valid value). */
    if (! PSA_ALG_IS_CIPHER(operation->alg))
        return (PSA_ERROR_BAD_STATE);

    if (operation->mbedtls_in_use == 0)
        psa_driver_wrapper_cipher_abort(&operation->ctx.driver);
    else
        mbedtls_cipher_free(&operation->ctx.cipher);

    operation->alg = 0;
    operation->key_set = 0;
    operation->iv_set = 0;
    operation->mbedtls_in_use = 0;
    operation->iv_size = 0;
    operation->block_size = 0;
    operation->iv_required = 0;

    return (PSA_SUCCESS);
}




/****************************************************************/
/* AEAD */
/****************************************************************/

typedef struct {
    psa_key_slot_t *slot;
    const mbedtls_cipher_info_t *cipher_info;
    union {
        unsigned dummy; /* Make the union non-empty even with no supported algorithms. */
#if defined(MBEDTLS_CCM_C)
        mbedtls_ccm_context ccm;
#endif /* MBEDTLS_CCM_C */
#if defined(MBEDTLS_GCM_C)
        mbedtls_gcm_context gcm;
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CHACHAPOLY_C)
        mbedtls_chachapoly_context chachapoly;
#endif /* MBEDTLS_CHACHAPOLY_C */
    } ctx;
    psa_algorithm_t core_alg;
    uint8_t full_tag_length;
    uint8_t tag_length;
} aead_operation_t;

#define AEAD_OPERATION_INIT {0, 0, {0}, 0, 0, 0}

static void psa_aead_abort_internal(aead_operation_t *operation) {
    switch (operation->core_alg) {
#if defined(MBEDTLS_CCM_C)
        case PSA_ALG_CCM:
            mbedtls_ccm_free(&operation->ctx.ccm);
            break;
#endif /* MBEDTLS_CCM_C */
#if defined(MBEDTLS_GCM_C)
        case PSA_ALG_GCM:
            mbedtls_gcm_free(&operation->ctx.gcm);
            break;
#endif /* MBEDTLS_GCM_C */
    }

    psa_unlock_key_slot(operation->slot);
}

static psa_status_t psa_aead_setup(aead_operation_t *operation,
                                   mbedtls_svc_key_id_t key,
                                   psa_key_usage_t usage,
                                   psa_algorithm_t alg) {
    psa_status_t status;
    size_t key_bits;
    mbedtls_cipher_id_t cipher_id;

    status = psa_get_and_lock_transparent_key_slot_with_policy(
                 key, &operation->slot, usage, alg);
    if (status != PSA_SUCCESS)
        return (status);

    key_bits = psa_get_key_slot_bits(operation->slot);

    operation->cipher_info =
        mbedtls_cipher_info_from_psa(alg, operation->slot->attr.type, key_bits,
                                     &cipher_id);
    if (operation->cipher_info == NULL) {
        status = PSA_ERROR_NOT_SUPPORTED;
        goto cleanup;
    }

    switch (PSA_ALG_AEAD_WITH_SHORTENED_TAG(alg, 0)) {
#if defined(MBEDTLS_CCM_C)
        case PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, 0):
            operation->core_alg = PSA_ALG_CCM;
            operation->full_tag_length = 16;
            /* CCM allows the following tag lengths: 4, 6, 8, 10, 12, 14, 16.
             * The call to mbedtls_ccm_encrypt_and_tag or
             * mbedtls_ccm_auth_decrypt will validate the tag length. */
            if (PSA_BLOCK_CIPHER_BLOCK_LENGTH(operation->slot->attr.type) != 16) {
                status = PSA_ERROR_INVALID_ARGUMENT;
                goto cleanup;
            }
            mbedtls_ccm_init(&operation->ctx.ccm);
            status = mbedtls_to_psa_error(
                         mbedtls_ccm_setkey(&operation->ctx.ccm, cipher_id,
                                            operation->slot->key.data,
                                            (unsigned int) key_bits));
            if (status != 0)
                goto cleanup;
            break;
#endif /* MBEDTLS_CCM_C */

#if defined(MBEDTLS_GCM_C)
        case PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_GCM, 0):
            operation->core_alg = PSA_ALG_GCM;
            operation->full_tag_length = 16;
            /* GCM allows the following tag lengths: 4, 8, 12, 13, 14, 15, 16.
             * The call to mbedtls_gcm_crypt_and_tag or
             * mbedtls_gcm_auth_decrypt will validate the tag length. */
            if (PSA_BLOCK_CIPHER_BLOCK_LENGTH(operation->slot->attr.type) != 16) {
                status = PSA_ERROR_INVALID_ARGUMENT;
                goto cleanup;
            }
            mbedtls_gcm_init(&operation->ctx.gcm);
            status = mbedtls_to_psa_error(
                         mbedtls_gcm_setkey(&operation->ctx.gcm, cipher_id,
                                            operation->slot->key.data,
                                            (unsigned int) key_bits));
            if (status != 0)
                goto cleanup;
            break;
#endif /* MBEDTLS_GCM_C */

#if defined(MBEDTLS_CHACHAPOLY_C)
        case PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CHACHA20_POLY1305, 0):
            operation->core_alg = PSA_ALG_CHACHA20_POLY1305;
            operation->full_tag_length = 16;
            /* We only support the default tag length. */
            if (alg != PSA_ALG_CHACHA20_POLY1305) {
                status = PSA_ERROR_NOT_SUPPORTED;
                goto cleanup;
            }
            mbedtls_chachapoly_init(&operation->ctx.chachapoly);
            status = mbedtls_to_psa_error(
                         mbedtls_chachapoly_setkey(&operation->ctx.chachapoly,
                                                   operation->slot->key.data));
            if (status != 0)
                goto cleanup;
            break;
#endif /* MBEDTLS_CHACHAPOLY_C */

        default:
            status = PSA_ERROR_NOT_SUPPORTED;
            goto cleanup;
    }

    if (PSA_AEAD_TAG_LENGTH(alg) > operation->full_tag_length) {
        status = PSA_ERROR_INVALID_ARGUMENT;
        goto cleanup;
    }
    operation->tag_length = PSA_AEAD_TAG_LENGTH(alg);

    return (PSA_SUCCESS);

cleanup:
    psa_aead_abort_internal(operation);
    return (status);
}

psa_status_t psa_aead_encrypt(mbedtls_svc_key_id_t key,
                              psa_algorithm_t alg,
                              const uint8_t *nonce,
                              size_t nonce_length,
                              const uint8_t *additional_data,
                              size_t additional_data_length,
                              const uint8_t *plaintext,
                              size_t plaintext_length,
                              uint8_t *ciphertext,
                              size_t ciphertext_size,
                              size_t *ciphertext_length) {
    psa_status_t status;
    aead_operation_t operation = AEAD_OPERATION_INIT;
    uint8_t *tag;

    *ciphertext_length = 0;

    status = psa_aead_setup(&operation, key, PSA_KEY_USAGE_ENCRYPT, alg);
    if (status != PSA_SUCCESS)
        return (status);

    /* For all currently supported modes, the tag is at the end of the
     * ciphertext. */
    if (ciphertext_size < (plaintext_length + operation.tag_length)) {
        status = PSA_ERROR_BUFFER_TOO_SMALL;
        goto exit;
    }
    tag = ciphertext + plaintext_length;

#if defined(MBEDTLS_GCM_C)
    if (operation.core_alg == PSA_ALG_GCM) {
        status = mbedtls_to_psa_error(
                     mbedtls_gcm_crypt_and_tag(&operation.ctx.gcm,
                                               MBEDTLS_GCM_ENCRYPT,
                                               plaintext_length,
                                               nonce, nonce_length,
                                               additional_data, additional_data_length,
                                               plaintext, ciphertext,
                                               operation.tag_length, tag));
    } else
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
        if (operation.core_alg == PSA_ALG_CCM) {
            status = mbedtls_to_psa_error(
                         mbedtls_ccm_encrypt_and_tag(&operation.ctx.ccm,
                                                     plaintext_length,
                                                     nonce, nonce_length,
                                                     additional_data,
                                                     additional_data_length,
                                                     plaintext, ciphertext,
                                                     tag, operation.tag_length));
        } else
#endif /* MBEDTLS_CCM_C */
#if defined(MBEDTLS_CHACHAPOLY_C)
            if (operation.core_alg == PSA_ALG_CHACHA20_POLY1305) {
                if (nonce_length != 12 || operation.tag_length != 16) {
                    status = PSA_ERROR_NOT_SUPPORTED;
                    goto exit;
                }
                status = mbedtls_to_psa_error(
                             mbedtls_chachapoly_encrypt_and_tag(&operation.ctx.chachapoly,
                                                                plaintext_length,
                                                                nonce,
                                                                additional_data,
                                                                additional_data_length,
                                                                plaintext,
                                                                ciphertext,
                                                                tag));
            } else
#endif /* MBEDTLS_CHACHAPOLY_C */
            {
                (void) tag;
                return (PSA_ERROR_NOT_SUPPORTED);
            }

    if (status != PSA_SUCCESS && ciphertext_size != 0)
        memset(ciphertext, 0, ciphertext_size);

exit:
    psa_aead_abort_internal(&operation);
    if (status == PSA_SUCCESS)
        *ciphertext_length = plaintext_length + operation.tag_length;
    return (status);
}

/* Locate the tag in a ciphertext buffer containing the encrypted data
 * followed by the tag. Return the length of the part preceding the tag in
 * *plaintext_length. This is the size of the plaintext in modes where
 * the encrypted data has the same size as the plaintext, such as
 * CCM and GCM. */
static psa_status_t psa_aead_unpadded_locate_tag(size_t tag_length,
                                                 const uint8_t *ciphertext,
                                                 size_t ciphertext_length,
                                                 size_t plaintext_size,
                                                 const uint8_t **p_tag) {
    size_t payload_length;
    if (tag_length > ciphertext_length)
        return (PSA_ERROR_INVALID_ARGUMENT);
    payload_length = ciphertext_length - tag_length;
    if (payload_length > plaintext_size)
        return (PSA_ERROR_BUFFER_TOO_SMALL);
    *p_tag = ciphertext + payload_length;
    return (PSA_SUCCESS);
}

psa_status_t psa_aead_decrypt(mbedtls_svc_key_id_t key,
                              psa_algorithm_t alg,
                              const uint8_t *nonce,
                              size_t nonce_length,
                              const uint8_t *additional_data,
                              size_t additional_data_length,
                              const uint8_t *ciphertext,
                              size_t ciphertext_length,
                              uint8_t *plaintext,
                              size_t plaintext_size,
                              size_t *plaintext_length) {
    psa_status_t status;
    aead_operation_t operation = AEAD_OPERATION_INIT;
    const uint8_t *tag = NULL;

    *plaintext_length = 0;

    status = psa_aead_setup(&operation, key, PSA_KEY_USAGE_DECRYPT, alg);
    if (status != PSA_SUCCESS)
        return (status);

    status = psa_aead_unpadded_locate_tag(operation.tag_length,
                                          ciphertext, ciphertext_length,
                                          plaintext_size, &tag);
    if (status != PSA_SUCCESS)
        goto exit;

#if defined(MBEDTLS_GCM_C)
    if (operation.core_alg == PSA_ALG_GCM) {
        status = mbedtls_to_psa_error(
                     mbedtls_gcm_auth_decrypt(&operation.ctx.gcm,
                                              ciphertext_length - operation.tag_length,
                                              nonce, nonce_length,
                                              additional_data,
                                              additional_data_length,
                                              tag, operation.tag_length,
                                              ciphertext, plaintext));
    } else
#endif /* MBEDTLS_GCM_C */
#if defined(MBEDTLS_CCM_C)
        if (operation.core_alg == PSA_ALG_CCM) {
            status = mbedtls_to_psa_error(
                         mbedtls_ccm_auth_decrypt(&operation.ctx.ccm,
                                                  ciphertext_length - operation.tag_length,
                                                  nonce, nonce_length,
                                                  additional_data,
                                                  additional_data_length,
                                                  ciphertext, plaintext,
                                                  tag, operation.tag_length));
        } else
#endif /* MBEDTLS_CCM_C */
#if defined(MBEDTLS_CHACHAPOLY_C)
            if (operation.core_alg == PSA_ALG_CHACHA20_POLY1305) {
                if (nonce_length != 12 || operation.tag_length != 16) {
                    status = PSA_ERROR_NOT_SUPPORTED;
                    goto exit;
                }
                status = mbedtls_to_psa_error(
                             mbedtls_chachapoly_auth_decrypt(&operation.ctx.chachapoly,
                                                             ciphertext_length - operation.tag_length,
                                                             nonce,
                                                             additional_data,
                                                             additional_data_length,
                                                             tag,
                                                             ciphertext,
                                                             plaintext));
            } else
#endif /* MBEDTLS_CHACHAPOLY_C */
            {
                return (PSA_ERROR_NOT_SUPPORTED);
            }

    if (status != PSA_SUCCESS && plaintext_size != 0)
        memset(plaintext, 0, plaintext_size);

exit:
    psa_aead_abort_internal(&operation);
    if (status == PSA_SUCCESS)
        *plaintext_length = ciphertext_length - operation.tag_length;
    return (status);
}



/****************************************************************/
/* Generators */
/****************************************************************/

#if defined(MBEDTLS_PSA_BUILTIN_ALG_HKDF) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
#define AT_LEAST_ONE_BUILTIN_KDF
#endif

#define HKDF_STATE_INIT 0 /* no input yet */
#define HKDF_STATE_STARTED 1 /* got salt */
#define HKDF_STATE_KEYED 2 /* got key */
#define HKDF_STATE_OUTPUT 3 /* output started */

static psa_algorithm_t psa_key_derivation_get_kdf_alg(
    const psa_key_derivation_operation_t *operation) {
    if (PSA_ALG_IS_KEY_AGREEMENT(operation->alg))
        return (PSA_ALG_KEY_AGREEMENT_GET_KDF(operation->alg));
    else
        return (operation->alg);
}

psa_status_t psa_key_derivation_abort(psa_key_derivation_operation_t *operation) {
    psa_status_t status = PSA_SUCCESS;
    psa_algorithm_t kdf_alg = psa_key_derivation_get_kdf_alg(operation);
    if (kdf_alg == 0) {
        /* The object has (apparently) been initialized but it is not
         * in use. It's ok to call abort on such an object, and there's
         * nothing to do. */
    } else
#if defined(MBEDTLS_PSA_BUILTIN_ALG_HKDF)
        if (PSA_ALG_IS_HKDF(kdf_alg)) {
            mbedtls_free(operation->ctx.hkdf.info);
            status = psa_hmac_abort_internal(&operation->ctx.hkdf.hmac);
        } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_HKDF */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
            if (PSA_ALG_IS_TLS12_PRF(kdf_alg) ||
                    /* TLS-1.2 PSK-to-MS KDF uses the same core as TLS-1.2 PRF */
                    PSA_ALG_IS_TLS12_PSK_TO_MS(kdf_alg)) {
                if (operation->ctx.tls12_prf.seed != NULL) {
                    mbedtls_platform_zeroize(operation->ctx.tls12_prf.seed,
                                             operation->ctx.tls12_prf.seed_length);
                    mbedtls_free(operation->ctx.tls12_prf.seed);
                }

                if (operation->ctx.tls12_prf.label != NULL) {
                    mbedtls_platform_zeroize(operation->ctx.tls12_prf.label,
                                             operation->ctx.tls12_prf.label_length);
                    mbedtls_free(operation->ctx.tls12_prf.label);
                }

                status = psa_hmac_abort_internal(&operation->ctx.tls12_prf.hmac);

                /* We leave the fields Ai and output_block to be erased safely by the
                 * mbedtls_platform_zeroize() in the end of this function. */
            } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF) ||
        * defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS) */
            {
                status = PSA_ERROR_BAD_STATE;
            }
    mbedtls_platform_zeroize(operation, sizeof(*operation));
    return (status);
}

psa_status_t psa_key_derivation_get_capacity(const psa_key_derivation_operation_t *operation,
                                             size_t *capacity) {
    if (operation->alg == 0) {
        /* This is a blank key derivation operation. */
        return (PSA_ERROR_BAD_STATE);
    }

    *capacity = operation->capacity;
    return (PSA_SUCCESS);
}

psa_status_t psa_key_derivation_set_capacity(psa_key_derivation_operation_t *operation,
                                             size_t capacity) {
    if (operation->alg == 0)
        return (PSA_ERROR_BAD_STATE);
    if (capacity > operation->capacity)
        return (PSA_ERROR_INVALID_ARGUMENT);
    operation->capacity = capacity;
    return (PSA_SUCCESS);
}

#if defined(MBEDTLS_PSA_BUILTIN_ALG_HKDF)
/* Read some bytes from an HKDF-based operation. This performs a chunk
 * of the expand phase of the HKDF algorithm. */
static psa_status_t psa_key_derivation_hkdf_read(psa_hkdf_key_derivation_t *hkdf,
                                                 psa_algorithm_t hash_alg,
                                                 uint8_t *output,
                                                 size_t output_length) {
    uint8_t hash_length = PSA_HASH_LENGTH(hash_alg);
    psa_status_t status;

    if (hkdf->state < HKDF_STATE_KEYED || ! hkdf->info_set)
        return (PSA_ERROR_BAD_STATE);
    hkdf->state = HKDF_STATE_OUTPUT;

    while (output_length != 0) {
        /* Copy what remains of the current block */
        uint8_t n = hash_length - hkdf->offset_in_block;
        if (n > output_length)
            n = (uint8_t) output_length;
        memcpy(output, hkdf->output_block + hkdf->offset_in_block, n);
        output += n;
        output_length -= n;
        hkdf->offset_in_block += n;
        if (output_length == 0)
            break;
        /* We can't be wanting more output after block 0xff, otherwise
         * the capacity check in psa_key_derivation_output_bytes() would have
         * prevented this call. It could happen only if the operation
         * object was corrupted or if this function is called directly
         * inside the library. */
        if (hkdf->block_number == 0xff)
            return (PSA_ERROR_BAD_STATE);

        /* We need a new block */
        ++hkdf->block_number;
        hkdf->offset_in_block = 0;
        status = psa_hmac_setup_internal(&hkdf->hmac,
                                         hkdf->prk, hash_length,
                                         hash_alg);
        if (status != PSA_SUCCESS)
            return (status);
        if (hkdf->block_number != 1) {
            status = psa_hash_update(&hkdf->hmac.hash_ctx,
                                     hkdf->output_block,
                                     hash_length);
            if (status != PSA_SUCCESS)
                return (status);
        }
        status = psa_hash_update(&hkdf->hmac.hash_ctx,
                                 hkdf->info,
                                 hkdf->info_length);
        if (status != PSA_SUCCESS)
            return (status);
        status = psa_hash_update(&hkdf->hmac.hash_ctx,
                                 &hkdf->block_number, 1);
        if (status != PSA_SUCCESS)
            return (status);
        status = psa_hmac_finish_internal(&hkdf->hmac,
                                          hkdf->output_block,
                                          sizeof(hkdf->output_block));
        if (status != PSA_SUCCESS)
            return (status);
    }

    return (PSA_SUCCESS);
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HKDF */

#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
static psa_status_t psa_key_derivation_tls12_prf_generate_next_block(
    psa_tls12_prf_key_derivation_t *tls12_prf,
    psa_algorithm_t alg) {
    psa_algorithm_t hash_alg = PSA_ALG_HKDF_GET_HASH(alg);
    uint8_t hash_length = PSA_HASH_LENGTH(hash_alg);
    psa_hash_operation_t backup = PSA_HASH_OPERATION_INIT;
    psa_status_t status, cleanup_status;

    /* We can't be wanting more output after block 0xff, otherwise
     * the capacity check in psa_key_derivation_output_bytes() would have
     * prevented this call. It could happen only if the operation
     * object was corrupted or if this function is called directly
     * inside the library. */
    if (tls12_prf->block_number == 0xff)
        return (PSA_ERROR_CORRUPTION_DETECTED);

    /* We need a new block */
    ++tls12_prf->block_number;
    tls12_prf->left_in_block = hash_length;

    /* Recall the definition of the TLS-1.2-PRF from RFC 5246:
     *
     * PRF(secret, label, seed) = P_<hash>(secret, label + seed)
     *
     * P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
     *                        HMAC_hash(secret, A(2) + seed) +
     *                        HMAC_hash(secret, A(3) + seed) + ...
     *
     * A(0) = seed
     * A(i) = HMAC_hash(secret, A(i-1))
     *
     * The `psa_tls12_prf_key_derivation` structure saves the block
     * `HMAC_hash(secret, A(i) + seed)` from which the output
     * is currently extracted as `output_block` and where i is
     * `block_number`.
     */

    /* Save the hash context before using it, to preserve the hash state with
     * only the inner padding in it. We need this, because inner padding depends
     * on the key (secret in the RFC's terminology). */
    status = psa_hash_clone(&tls12_prf->hmac.hash_ctx, &backup);
    if (status != PSA_SUCCESS)
        goto cleanup;

    /* Calculate A(i) where i = tls12_prf->block_number. */
    if (tls12_prf->block_number == 1) {
        /* A(1) = HMAC_hash(secret, A(0)), where A(0) = seed. (The RFC overloads
         * the variable seed and in this instance means it in the context of the
         * P_hash function, where seed = label + seed.) */
        status = psa_hash_update(&tls12_prf->hmac.hash_ctx,
                                 tls12_prf->label, tls12_prf->label_length);
        if (status != PSA_SUCCESS)
            goto cleanup;
        status = psa_hash_update(&tls12_prf->hmac.hash_ctx,
                                 tls12_prf->seed, tls12_prf->seed_length);
        if (status != PSA_SUCCESS)
            goto cleanup;
    } else {
        /* A(i) = HMAC_hash(secret, A(i-1)) */
        status = psa_hash_update(&tls12_prf->hmac.hash_ctx,
                                 tls12_prf->Ai, hash_length);
        if (status != PSA_SUCCESS)
            goto cleanup;
    }

    status = psa_hmac_finish_internal(&tls12_prf->hmac,
                                      tls12_prf->Ai, hash_length);
    if (status != PSA_SUCCESS)
        goto cleanup;
    status = psa_hash_clone(&backup, &tls12_prf->hmac.hash_ctx);
    if (status != PSA_SUCCESS)
        goto cleanup;

    /* Calculate HMAC_hash(secret, A(i) + label + seed). */
    status = psa_hash_update(&tls12_prf->hmac.hash_ctx,
                             tls12_prf->Ai, hash_length);
    if (status != PSA_SUCCESS)
        goto cleanup;
    status = psa_hash_update(&tls12_prf->hmac.hash_ctx,
                             tls12_prf->label, tls12_prf->label_length);
    if (status != PSA_SUCCESS)
        goto cleanup;
    status = psa_hash_update(&tls12_prf->hmac.hash_ctx,
                             tls12_prf->seed, tls12_prf->seed_length);
    if (status != PSA_SUCCESS)
        goto cleanup;
    status = psa_hmac_finish_internal(&tls12_prf->hmac,
                                      tls12_prf->output_block, hash_length);
    if (status != PSA_SUCCESS)
        goto cleanup;
    status = psa_hash_clone(&backup, &tls12_prf->hmac.hash_ctx);
    if (status != PSA_SUCCESS)
        goto cleanup;


cleanup:

    cleanup_status = psa_hash_abort(&backup);
    if (status == PSA_SUCCESS && cleanup_status != PSA_SUCCESS)
        status = cleanup_status;

    return (status);
}

static psa_status_t psa_key_derivation_tls12_prf_read(
    psa_tls12_prf_key_derivation_t *tls12_prf,
    psa_algorithm_t alg,
    uint8_t *output,
    size_t output_length) {
    psa_algorithm_t hash_alg = PSA_ALG_TLS12_PRF_GET_HASH(alg);
    uint8_t hash_length = PSA_HASH_LENGTH(hash_alg);
    psa_status_t status;
    uint8_t offset, length;

    while (output_length != 0) {
        /* Check if we have fully processed the current block. */
        if (tls12_prf->left_in_block == 0) {
            status = psa_key_derivation_tls12_prf_generate_next_block(tls12_prf,
                                                                      alg);
            if (status != PSA_SUCCESS)
                return (status);

            continue;
        }

        if (tls12_prf->left_in_block > output_length)
            length = (uint8_t) output_length;
        else
            length = tls12_prf->left_in_block;

        offset = hash_length - tls12_prf->left_in_block;
        memcpy(output, tls12_prf->output_block + offset, length);
        output += length;
        output_length -= length;
        tls12_prf->left_in_block -= length;
    }

    return (PSA_SUCCESS);
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF ||
        * MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS */

psa_status_t psa_key_derivation_output_bytes(
    psa_key_derivation_operation_t *operation,
    uint8_t *output,
    size_t output_length) {
    psa_status_t status;
    psa_algorithm_t kdf_alg = psa_key_derivation_get_kdf_alg(operation);

    if (operation->alg == 0) {
        /* This is a blank operation. */
        return (PSA_ERROR_BAD_STATE);
    }

    if (output_length > operation->capacity) {
        operation->capacity = 0;
        /* Go through the error path to wipe all confidential data now
         * that the operation object is useless. */
        status = PSA_ERROR_INSUFFICIENT_DATA;
        goto exit;
    }
    if (output_length == 0 && operation->capacity == 0) {
        /* Edge case: this is a finished operation, and 0 bytes
         * were requested. The right error in this case could
         * be either INSUFFICIENT_CAPACITY or BAD_STATE. Return
         * INSUFFICIENT_CAPACITY, which is right for a finished
         * operation, for consistency with the case when
         * output_length > 0. */
        return (PSA_ERROR_INSUFFICIENT_DATA);
    }
    operation->capacity -= output_length;

#if defined(MBEDTLS_PSA_BUILTIN_ALG_HKDF)
    if (PSA_ALG_IS_HKDF(kdf_alg)) {
        psa_algorithm_t hash_alg = PSA_ALG_HKDF_GET_HASH(kdf_alg);
        status = psa_key_derivation_hkdf_read(&operation->ctx.hkdf, hash_alg,
                                              output, output_length);
    } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HKDF */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
        if (PSA_ALG_IS_TLS12_PRF(kdf_alg) ||
                PSA_ALG_IS_TLS12_PSK_TO_MS(kdf_alg)) {
            status = psa_key_derivation_tls12_prf_read(&operation->ctx.tls12_prf,
                                                       kdf_alg, output,
                                                       output_length);
        } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF ||
        * MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS */
        {
            (void) kdf_alg;
            return (PSA_ERROR_BAD_STATE);
        }

exit:
    if (status != PSA_SUCCESS) {
        /* Preserve the algorithm upon errors, but clear all sensitive state.
         * This allows us to differentiate between exhausted operations and
         * blank operations, so we can return PSA_ERROR_BAD_STATE on blank
         * operations. */
        psa_algorithm_t alg = operation->alg;
        psa_key_derivation_abort(operation);
        operation->alg = alg;
        memset(output, '!', output_length);
    }
    return (status);
}

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES)
static void psa_des_set_key_parity(uint8_t *data, size_t data_size) {
    if (data_size >= 8)
        mbedtls_des_key_set_parity(data);
    if (data_size >= 16)
        mbedtls_des_key_set_parity(data + 8);
    if (data_size >= 24)
        mbedtls_des_key_set_parity(data + 16);
}
#endif /* MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES */

static psa_status_t psa_generate_derived_key_internal(
    psa_key_slot_t *slot,
    size_t bits,
    psa_key_derivation_operation_t *operation) {
    uint8_t *data = NULL;
    size_t bytes = PSA_BITS_TO_BYTES(bits);
    psa_status_t status;

    if (! key_type_is_raw_bytes(slot->attr.type))
        return (PSA_ERROR_INVALID_ARGUMENT);
    if (bits % 8 != 0)
        return (PSA_ERROR_INVALID_ARGUMENT);
    data = mbedtls_calloc(1, bytes);
    if (data == NULL)
        return (PSA_ERROR_INSUFFICIENT_MEMORY);

    status = psa_key_derivation_output_bytes(operation, data, bytes);
    if (status != PSA_SUCCESS)
        goto exit;
#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES)
    if (slot->attr.type == PSA_KEY_TYPE_DES)
        psa_des_set_key_parity(data, bytes);
#endif /* MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES */

    status = psa_allocate_buffer_to_slot(slot, bytes);
    if (status != PSA_SUCCESS)
        goto exit;

    slot->attr.bits = (psa_key_bits_t) bits;
    psa_key_attributes_t attributes = {
        .core = slot->attr
    };

    status = psa_driver_wrapper_import_key(&attributes,
                                           data, bytes,
                                           slot->key.data,
                                           slot->key.bytes,
                                           &slot->key.bytes, &bits);
    if (bits != slot->attr.bits)
        status = PSA_ERROR_INVALID_ARGUMENT;

exit:
    mbedtls_free(data);
    return (status);
}

psa_status_t psa_key_derivation_output_key(const psa_key_attributes_t *attributes,
                                           psa_key_derivation_operation_t *operation,
                                           mbedtls_svc_key_id_t *key) {
    psa_status_t status;
    psa_key_slot_t *slot = NULL;
    psa_se_drv_table_entry_t *driver = NULL;

    *key = MBEDTLS_SVC_KEY_ID_INIT;

    /* Reject any attempt to create a zero-length key so that we don't
     * risk tripping up later, e.g. on a malloc(0) that returns NULL. */
    if (psa_get_key_bits(attributes) == 0)
        return (PSA_ERROR_INVALID_ARGUMENT);

    if (! operation->can_output_key)
        return (PSA_ERROR_NOT_PERMITTED);

    status = psa_start_key_creation(PSA_KEY_CREATION_DERIVE, attributes,
                                    &slot, &driver);
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    if (driver != NULL) {
        /* Deriving a key in a secure element is not implemented yet. */
        status = PSA_ERROR_NOT_SUPPORTED;
    }
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
    if (status == PSA_SUCCESS) {
        status = psa_generate_derived_key_internal(slot,
                                                   attributes->core.bits,
                                                   operation);
    }
    if (status == PSA_SUCCESS)
        status = psa_finish_key_creation(slot, driver, key);
    if (status != PSA_SUCCESS)
        psa_fail_key_creation(slot, driver);

    return (status);
}



/****************************************************************/
/* Key derivation */
/****************************************************************/

#if defined(AT_LEAST_ONE_BUILTIN_KDF)
static psa_status_t psa_key_derivation_setup_kdf(
    psa_key_derivation_operation_t *operation,
    psa_algorithm_t kdf_alg) {
    int is_kdf_alg_supported;

    /* Make sure that operation->ctx is properly zero-initialised. (Macro
     * initialisers for this union leave some bytes unspecified.) */
    memset(&operation->ctx, 0, sizeof(operation->ctx));

    /* Make sure that kdf_alg is a supported key derivation algorithm. */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_HKDF)
    if (PSA_ALG_IS_HKDF(kdf_alg))
        is_kdf_alg_supported = 1;
    else
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF)
        if (PSA_ALG_IS_TLS12_PRF(kdf_alg))
            is_kdf_alg_supported = 1;
        else
#endif
#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
            if (PSA_ALG_IS_TLS12_PSK_TO_MS(kdf_alg))
                is_kdf_alg_supported = 1;
            else
#endif
                is_kdf_alg_supported = 0;

    if (is_kdf_alg_supported) {
        psa_algorithm_t hash_alg = PSA_ALG_HKDF_GET_HASH(kdf_alg);
        size_t hash_size = PSA_HASH_LENGTH(hash_alg);
        if (hash_size == 0)
            return (PSA_ERROR_NOT_SUPPORTED);
        if ((PSA_ALG_IS_TLS12_PRF(kdf_alg) ||
                PSA_ALG_IS_TLS12_PSK_TO_MS(kdf_alg)) &&
                !(hash_alg == PSA_ALG_SHA_256 || hash_alg == PSA_ALG_SHA_384)) {
            return (PSA_ERROR_NOT_SUPPORTED);
        }
        operation->capacity = 255 * hash_size;
        return (PSA_SUCCESS);
    }

    return (PSA_ERROR_NOT_SUPPORTED);
}
#endif /* AT_LEAST_ONE_BUILTIN_KDF */

psa_status_t psa_key_derivation_setup(psa_key_derivation_operation_t *operation,
                                      psa_algorithm_t alg) {
    psa_status_t status;

    if (operation->alg != 0)
        return (PSA_ERROR_BAD_STATE);

    if (PSA_ALG_IS_RAW_KEY_AGREEMENT(alg))
        return (PSA_ERROR_INVALID_ARGUMENT);
    else if (PSA_ALG_IS_KEY_AGREEMENT(alg)) {
#if defined(AT_LEAST_ONE_BUILTIN_KDF)
        psa_algorithm_t kdf_alg = PSA_ALG_KEY_AGREEMENT_GET_KDF(alg);
        status = psa_key_derivation_setup_kdf(operation, kdf_alg);
#else
        return (PSA_ERROR_NOT_SUPPORTED);
#endif /* AT_LEAST_ONE_BUILTIN_KDF */
    } else if (PSA_ALG_IS_KEY_DERIVATION(alg)) {
#if defined(AT_LEAST_ONE_BUILTIN_KDF)
        status = psa_key_derivation_setup_kdf(operation, alg);
#else
        return (PSA_ERROR_NOT_SUPPORTED);
#endif /* AT_LEAST_ONE_BUILTIN_KDF */
    } else
        return (PSA_ERROR_INVALID_ARGUMENT);

    if (status == PSA_SUCCESS)
        operation->alg = alg;
    return (status);
}

#if defined(MBEDTLS_PSA_BUILTIN_ALG_HKDF)
static psa_status_t psa_hkdf_input(psa_hkdf_key_derivation_t *hkdf,
                                   psa_algorithm_t hash_alg,
                                   psa_key_derivation_step_t step,
                                   const uint8_t *data,
                                   size_t data_length) {
    psa_status_t status;
    switch (step) {
        case PSA_KEY_DERIVATION_INPUT_SALT:
            if (hkdf->state != HKDF_STATE_INIT)
                return (PSA_ERROR_BAD_STATE);
            status = psa_hmac_setup_internal(&hkdf->hmac,
                                             data, data_length,
                                             hash_alg);
            if (status != PSA_SUCCESS)
                return (status);
            hkdf->state = HKDF_STATE_STARTED;
            return (PSA_SUCCESS);
        case PSA_KEY_DERIVATION_INPUT_SECRET:
            /* If no salt was provided, use an empty salt. */
            if (hkdf->state == HKDF_STATE_INIT) {
                status = psa_hmac_setup_internal(&hkdf->hmac,
                                                 NULL, 0,
                                                 hash_alg);
                if (status != PSA_SUCCESS)
                    return (status);
                hkdf->state = HKDF_STATE_STARTED;
            }
            if (hkdf->state != HKDF_STATE_STARTED)
                return (PSA_ERROR_BAD_STATE);
            status = psa_hash_update(&hkdf->hmac.hash_ctx,
                                     data, data_length);
            if (status != PSA_SUCCESS)
                return (status);
            status = psa_hmac_finish_internal(&hkdf->hmac,
                                              hkdf->prk,
                                              sizeof(hkdf->prk));
            if (status != PSA_SUCCESS)
                return (status);
            hkdf->offset_in_block = PSA_HASH_LENGTH(hash_alg);
            hkdf->block_number = 0;
            hkdf->state = HKDF_STATE_KEYED;
            return (PSA_SUCCESS);
        case PSA_KEY_DERIVATION_INPUT_INFO:
            if (hkdf->state == HKDF_STATE_OUTPUT)
                return (PSA_ERROR_BAD_STATE);
            if (hkdf->info_set)
                return (PSA_ERROR_BAD_STATE);
            hkdf->info_length = data_length;
            if (data_length != 0) {
                hkdf->info = mbedtls_calloc(1, data_length);
                if (hkdf->info == NULL)
                    return (PSA_ERROR_INSUFFICIENT_MEMORY);
                memcpy(hkdf->info, data, data_length);
            }
            hkdf->info_set = 1;
            return (PSA_SUCCESS);
        default:
            return (PSA_ERROR_INVALID_ARGUMENT);
    }
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HKDF */

#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF) || \
    defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
static psa_status_t psa_tls12_prf_set_seed(psa_tls12_prf_key_derivation_t *prf,
                                           const uint8_t *data,
                                           size_t data_length) {
    if (prf->state != PSA_TLS12_PRF_STATE_INIT)
        return (PSA_ERROR_BAD_STATE);

    if (data_length != 0) {
        prf->seed = mbedtls_calloc(1, data_length);
        if (prf->seed == NULL)
            return (PSA_ERROR_INSUFFICIENT_MEMORY);

        memcpy(prf->seed, data, data_length);
        prf->seed_length = data_length;
    }

    prf->state = PSA_TLS12_PRF_STATE_SEED_SET;

    return (PSA_SUCCESS);
}

static psa_status_t psa_tls12_prf_set_key(psa_tls12_prf_key_derivation_t *prf,
                                          psa_algorithm_t hash_alg,
                                          const uint8_t *data,
                                          size_t data_length) {
    psa_status_t status;
    if (prf->state != PSA_TLS12_PRF_STATE_SEED_SET)
        return (PSA_ERROR_BAD_STATE);

    status = psa_hmac_setup_internal(&prf->hmac, data, data_length, hash_alg);
    if (status != PSA_SUCCESS)
        return (status);

    prf->state = PSA_TLS12_PRF_STATE_KEY_SET;

    return (PSA_SUCCESS);
}

static psa_status_t psa_tls12_prf_set_label(psa_tls12_prf_key_derivation_t *prf,
                                            const uint8_t *data,
                                            size_t data_length) {
    if (prf->state != PSA_TLS12_PRF_STATE_KEY_SET)
        return (PSA_ERROR_BAD_STATE);

    if (data_length != 0) {
        prf->label = mbedtls_calloc(1, data_length);
        if (prf->label == NULL)
            return (PSA_ERROR_INSUFFICIENT_MEMORY);

        memcpy(prf->label, data, data_length);
        prf->label_length = data_length;
    }

    prf->state = PSA_TLS12_PRF_STATE_LABEL_SET;

    return (PSA_SUCCESS);
}

static psa_status_t psa_tls12_prf_input(psa_tls12_prf_key_derivation_t *prf,
                                        psa_algorithm_t hash_alg,
                                        psa_key_derivation_step_t step,
                                        const uint8_t *data,
                                        size_t data_length) {
    switch (step) {
        case PSA_KEY_DERIVATION_INPUT_SEED:
            return (psa_tls12_prf_set_seed(prf, data, data_length));
        case PSA_KEY_DERIVATION_INPUT_SECRET:
            return (psa_tls12_prf_set_key(prf, hash_alg, data, data_length));
        case PSA_KEY_DERIVATION_INPUT_LABEL:
            return (psa_tls12_prf_set_label(prf, data, data_length));
        default:
            return (PSA_ERROR_INVALID_ARGUMENT);
    }
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF) ||
        * MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS */

#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
static psa_status_t psa_tls12_prf_psk_to_ms_set_key(
    psa_tls12_prf_key_derivation_t *prf,
    psa_algorithm_t hash_alg,
    const uint8_t *data,
    size_t data_length) {
    psa_status_t status;
    uint8_t pms[ 4 + 2 * PSA_TLS12_PSK_TO_MS_PSK_MAX_SIZE ];
    uint8_t *cur = pms;

    if (data_length > PSA_TLS12_PSK_TO_MS_PSK_MAX_SIZE)
        return (PSA_ERROR_INVALID_ARGUMENT);

    /* Quoting RFC 4279, Section 2:
     *
     * The premaster secret is formed as follows: if the PSK is N octets
     * long, concatenate a uint16 with the value N, N zero octets, a second
     * uint16 with the value N, and the PSK itself.
     */

    *cur++ = (data_length >> 8) & 0xff;
    *cur++ = (data_length >> 0) & 0xff;
    memset(cur, 0, data_length);
    cur += data_length;
    *cur++ = pms[0];
    *cur++ = pms[1];
    memcpy(cur, data, data_length);
    cur += data_length;

    status = psa_tls12_prf_set_key(prf, hash_alg, pms, cur - pms);

    mbedtls_platform_zeroize(pms, sizeof(pms));
    return (status);
}

static psa_status_t psa_tls12_prf_psk_to_ms_input(
    psa_tls12_prf_key_derivation_t *prf,
    psa_algorithm_t hash_alg,
    psa_key_derivation_step_t step,
    const uint8_t *data,
    size_t data_length) {
    if (step == PSA_KEY_DERIVATION_INPUT_SECRET) {
        return (psa_tls12_prf_psk_to_ms_set_key(prf, hash_alg,
                                                data, data_length));
    }

    return (psa_tls12_prf_input(prf, hash_alg, step, data, data_length));
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS */

/** Check whether the given key type is acceptable for the given
 * input step of a key derivation.
 *
 * Secret inputs must have the type #PSA_KEY_TYPE_DERIVE.
 * Non-secret inputs must have the type #PSA_KEY_TYPE_RAW_DATA.
 * Both secret and non-secret inputs can alternatively have the type
 * #PSA_KEY_TYPE_NONE, which is never the type of a key object, meaning
 * that the input was passed as a buffer rather than via a key object.
 */
static int psa_key_derivation_check_input_type(
    psa_key_derivation_step_t step,
    psa_key_type_t key_type) {
    switch (step) {
        case PSA_KEY_DERIVATION_INPUT_SECRET:
            if (key_type == PSA_KEY_TYPE_DERIVE)
                return (PSA_SUCCESS);
            if (key_type == PSA_KEY_TYPE_NONE)
                return (PSA_SUCCESS);
            break;
        case PSA_KEY_DERIVATION_INPUT_LABEL:
        case PSA_KEY_DERIVATION_INPUT_SALT:
        case PSA_KEY_DERIVATION_INPUT_INFO:
        case PSA_KEY_DERIVATION_INPUT_SEED:
            if (key_type == PSA_KEY_TYPE_RAW_DATA)
                return (PSA_SUCCESS);
            if (key_type == PSA_KEY_TYPE_NONE)
                return (PSA_SUCCESS);
            break;
    }
    return (PSA_ERROR_INVALID_ARGUMENT);
}

static psa_status_t psa_key_derivation_input_internal(
    psa_key_derivation_operation_t *operation,
    psa_key_derivation_step_t step,
    psa_key_type_t key_type,
    const uint8_t *data,
    size_t data_length) {
    psa_status_t status;
    psa_algorithm_t kdf_alg = psa_key_derivation_get_kdf_alg(operation);

    status = psa_key_derivation_check_input_type(step, key_type);
    if (status != PSA_SUCCESS)
        goto exit;

#if defined(MBEDTLS_PSA_BUILTIN_ALG_HKDF)
    if (PSA_ALG_IS_HKDF(kdf_alg)) {
        status = psa_hkdf_input(&operation->ctx.hkdf,
                                PSA_ALG_HKDF_GET_HASH(kdf_alg),
                                step, data, data_length);
    } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_HKDF */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF)
        if (PSA_ALG_IS_TLS12_PRF(kdf_alg)) {
            status = psa_tls12_prf_input(&operation->ctx.tls12_prf,
                                         PSA_ALG_HKDF_GET_HASH(kdf_alg),
                                         step, data, data_length);
        } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_TLS12_PRF */
#if defined(MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS)
            if (PSA_ALG_IS_TLS12_PSK_TO_MS(kdf_alg)) {
                status = psa_tls12_prf_psk_to_ms_input(&operation->ctx.tls12_prf,
                                                       PSA_ALG_HKDF_GET_HASH(kdf_alg),
                                                       step, data, data_length);
            } else
#endif /* MBEDTLS_PSA_BUILTIN_ALG_TLS12_PSK_TO_MS */
            {
                /* This can't happen unless the operation object was not initialized */
                (void) data;
                (void) data_length;
                (void) kdf_alg;
                return (PSA_ERROR_BAD_STATE);
            }

exit:
    if (status != PSA_SUCCESS)
        psa_key_derivation_abort(operation);
    return (status);
}

psa_status_t psa_key_derivation_input_bytes(
    psa_key_derivation_operation_t *operation,
    psa_key_derivation_step_t step,
    const uint8_t *data,
    size_t data_length) {
    return (psa_key_derivation_input_internal(operation, step,
                                              PSA_KEY_TYPE_NONE,
                                              data, data_length));
}

psa_status_t psa_key_derivation_input_key(
    psa_key_derivation_operation_t *operation,
    psa_key_derivation_step_t step,
    mbedtls_svc_key_id_t key) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    status = psa_get_and_lock_transparent_key_slot_with_policy(
                 key, &slot, PSA_KEY_USAGE_DERIVE, operation->alg);
    if (status != PSA_SUCCESS) {
        psa_key_derivation_abort(operation);
        return (status);
    }

    /* Passing a key object as a SECRET input unlocks the permission
     * to output to a key object. */
    if (step == PSA_KEY_DERIVATION_INPUT_SECRET)
        operation->can_output_key = 1;

    status = psa_key_derivation_input_internal(operation,
                                               step, slot->attr.type,
                                               slot->key.data,
                                               slot->key.bytes);

    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}



/****************************************************************/
/* Key agreement */
/****************************************************************/

#if defined(MBEDTLS_PSA_BUILTIN_ALG_ECDH)
static psa_status_t psa_key_agreement_ecdh(const uint8_t *peer_key,
                                           size_t peer_key_length,
                                           const mbedtls_ecp_keypair *our_key,
                                           uint8_t *shared_secret,
                                           size_t shared_secret_size,
                                           size_t *shared_secret_length) {
    mbedtls_ecp_keypair *their_key = NULL;
    mbedtls_ecdh_context ecdh;
    psa_status_t status;
    size_t bits = 0;
    psa_ecc_family_t curve = mbedtls_ecc_group_to_psa(our_key->grp.id, &bits);
    mbedtls_ecdh_init(&ecdh);

    status = mbedtls_psa_ecp_load_representation(
                 PSA_KEY_TYPE_ECC_PUBLIC_KEY(curve),
                 bits,
                 peer_key,
                 peer_key_length,
                 &their_key);
    if (status != PSA_SUCCESS)
        goto exit;

    status = mbedtls_to_psa_error(
                 mbedtls_ecdh_get_params(&ecdh, their_key, MBEDTLS_ECDH_THEIRS));
    if (status != PSA_SUCCESS)
        goto exit;
    status = mbedtls_to_psa_error(
                 mbedtls_ecdh_get_params(&ecdh, our_key, MBEDTLS_ECDH_OURS));
    if (status != PSA_SUCCESS)
        goto exit;

    status = mbedtls_to_psa_error(
                 mbedtls_ecdh_calc_secret(&ecdh,
                                          shared_secret_length,
                                          shared_secret, shared_secret_size,
                                          mbedtls_psa_get_random,
                                          MBEDTLS_PSA_RANDOM_STATE));
    if (status != PSA_SUCCESS)
        goto exit;
    if (PSA_BITS_TO_BYTES(bits) != *shared_secret_length)
        status = PSA_ERROR_CORRUPTION_DETECTED;

exit:
    if (status != PSA_SUCCESS)
        mbedtls_platform_zeroize(shared_secret, shared_secret_size);
    mbedtls_ecdh_free(&ecdh);
    mbedtls_ecp_keypair_free(their_key);
    mbedtls_free(their_key);

    return (status);
}
#endif /* MBEDTLS_PSA_BUILTIN_ALG_ECDH */

#define PSA_KEY_AGREEMENT_MAX_SHARED_SECRET_SIZE MBEDTLS_ECP_MAX_BYTES

static psa_status_t psa_key_agreement_raw_internal(psa_algorithm_t alg,
                                                   psa_key_slot_t *private_key,
                                                   const uint8_t *peer_key,
                                                   size_t peer_key_length,
                                                   uint8_t *shared_secret,
                                                   size_t shared_secret_size,
                                                   size_t *shared_secret_length) {
    switch (alg) {
#if defined(MBEDTLS_PSA_BUILTIN_ALG_ECDH)
        case PSA_ALG_ECDH:
            if (! PSA_KEY_TYPE_IS_ECC_KEY_PAIR(private_key->attr.type))
                return (PSA_ERROR_INVALID_ARGUMENT);
            mbedtls_ecp_keypair *ecp = NULL;
            psa_status_t status = mbedtls_psa_ecp_load_representation(
                                      private_key->attr.type,
                                      private_key->attr.bits,
                                      private_key->key.data,
                                      private_key->key.bytes,
                                      &ecp);
            if (status != PSA_SUCCESS)
                return (status);
            status = psa_key_agreement_ecdh(peer_key, peer_key_length,
                                            ecp,
                                            shared_secret, shared_secret_size,
                                            shared_secret_length);
            mbedtls_ecp_keypair_free(ecp);
            mbedtls_free(ecp);
            return (status);
#endif /* MBEDTLS_PSA_BUILTIN_ALG_ECDH */
        default:
            (void) private_key;
            (void) peer_key;
            (void) peer_key_length;
            (void) shared_secret;
            (void) shared_secret_size;
            (void) shared_secret_length;
            return (PSA_ERROR_NOT_SUPPORTED);
    }
}

/* Note that if this function fails, you must call psa_key_derivation_abort()
 * to potentially free embedded data structures and wipe confidential data.
 */
static psa_status_t psa_key_agreement_internal(psa_key_derivation_operation_t *operation,
                                               psa_key_derivation_step_t step,
                                               psa_key_slot_t *private_key,
                                               const uint8_t *peer_key,
                                               size_t peer_key_length) {
    psa_status_t status;
    uint8_t shared_secret[PSA_KEY_AGREEMENT_MAX_SHARED_SECRET_SIZE];
    size_t shared_secret_length = 0;
    psa_algorithm_t ka_alg = PSA_ALG_KEY_AGREEMENT_GET_BASE(operation->alg);

    /* Step 1: run the secret agreement algorithm to generate the shared
     * secret. */
    status = psa_key_agreement_raw_internal(ka_alg,
                                            private_key,
                                            peer_key, peer_key_length,
                                            shared_secret,
                                            sizeof(shared_secret),
                                            &shared_secret_length);
    if (status != PSA_SUCCESS)
        goto exit;

    /* Step 2: set up the key derivation to generate key material from
     * the shared secret. A shared secret is permitted wherever a key
     * of type DERIVE is permitted. */
    status = psa_key_derivation_input_internal(operation, step,
                                               PSA_KEY_TYPE_DERIVE,
                                               shared_secret,
                                               shared_secret_length);
exit:
    mbedtls_platform_zeroize(shared_secret, shared_secret_length);
    return (status);
}

psa_status_t psa_key_derivation_key_agreement(psa_key_derivation_operation_t *operation,
                                              psa_key_derivation_step_t step,
                                              mbedtls_svc_key_id_t private_key,
                                              const uint8_t *peer_key,
                                              size_t peer_key_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot;

    if (! PSA_ALG_IS_KEY_AGREEMENT(operation->alg))
        return (PSA_ERROR_INVALID_ARGUMENT);
    status = psa_get_and_lock_transparent_key_slot_with_policy(
                 private_key, &slot, PSA_KEY_USAGE_DERIVE, operation->alg);
    if (status != PSA_SUCCESS)
        return (status);
    status = psa_key_agreement_internal(operation, step,
                                        slot,
                                        peer_key, peer_key_length);
    if (status != PSA_SUCCESS)
        psa_key_derivation_abort(operation);
    else {
        /* If a private key has been added as SECRET, we allow the derived
         * key material to be used as a key in PSA Crypto. */
        if (step == PSA_KEY_DERIVATION_INPUT_SECRET)
            operation->can_output_key = 1;
    }

    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}

psa_status_t psa_raw_key_agreement(psa_algorithm_t alg,
                                   mbedtls_svc_key_id_t private_key,
                                   const uint8_t *peer_key,
                                   size_t peer_key_length,
                                   uint8_t *output,
                                   size_t output_size,
                                   size_t *output_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_slot_t *slot = NULL;

    if (! PSA_ALG_IS_KEY_AGREEMENT(alg)) {
        status = PSA_ERROR_INVALID_ARGUMENT;
        goto exit;
    }
    status = psa_get_and_lock_transparent_key_slot_with_policy(
                 private_key, &slot, PSA_KEY_USAGE_DERIVE, alg);
    if (status != PSA_SUCCESS)
        goto exit;

    status = psa_key_agreement_raw_internal(alg, slot,
                                            peer_key, peer_key_length,
                                            output, output_size,
                                            output_length);

exit:
    if (status != PSA_SUCCESS) {
        /* If an error happens and is not handled properly, the output
         * may be used as a key to protect sensitive data. Arrange for such
         * a key to be random, which is likely to result in decryption or
         * verification errors. This is better than filling the buffer with
         * some constant data such as zeros, which would result in the data
         * being protected with a reproducible, easily knowable key.
         */
        psa_generate_random(output, output_size);
        *output_length = output_size;
    }

    unlock_status = psa_unlock_key_slot(slot);

    return ((status == PSA_SUCCESS) ? unlock_status : status);
}



/****************************************************************/
/* Random generation */
/****************************************************************/

/** Initialize the PSA random generator.
 */
static void mbedtls_psa_random_init(mbedtls_psa_random_context_t *rng) {
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
    memset(rng, 0, sizeof(*rng));
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */

    /* Set default configuration if
     * mbedtls_psa_crypto_configure_entropy_sources() hasn't been called. */
    if (rng->entropy_init == NULL)
        rng->entropy_init = mbedtls_entropy_init;
    if (rng->entropy_free == NULL)
        rng->entropy_free = mbedtls_entropy_free;

    rng->entropy_init(&rng->entropy);
#if defined(MBEDTLS_PSA_INJECT_ENTROPY) && \
    defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES)
    /* The PSA entropy injection feature depends on using NV seed as an entropy
     * source. Add NV seed as an entropy source for PSA entropy injection. */
    mbedtls_entropy_add_source(&rng->entropy,
                               mbedtls_nv_seed_poll, NULL,
                               MBEDTLS_ENTROPY_BLOCK_SIZE,
                               MBEDTLS_ENTROPY_SOURCE_STRONG);
#endif

    mbedtls_psa_drbg_init(MBEDTLS_PSA_RANDOM_STATE);
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}

/** Deinitialize the PSA random generator.
 */
static void mbedtls_psa_random_free(mbedtls_psa_random_context_t *rng) {
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
    memset(rng, 0, sizeof(*rng));
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
    mbedtls_psa_drbg_free(MBEDTLS_PSA_RANDOM_STATE);
    rng->entropy_free(&rng->entropy);
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}

/** Seed the PSA random generator.
 */
static psa_status_t mbedtls_psa_random_seed(mbedtls_psa_random_context_t *rng) {
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
    /* Do nothing: the external RNG seeds itself. */
    (void) rng;
    return (PSA_SUCCESS);
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
    const unsigned char drbg_seed[] = "PSA";
    int ret = mbedtls_psa_drbg_seed(&rng->entropy,
                                    drbg_seed, sizeof(drbg_seed) - 1);
    return mbedtls_to_psa_error(ret);
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}

psa_status_t psa_generate_random(uint8_t *output,
                                 size_t output_size) {
    GUARD_MODULE_INITIALIZED;

#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)

    size_t output_length = 0;
    psa_status_t status = mbedtls_psa_external_get_random(&global_data.rng,
                                                          output, output_size,
                                                          &output_length);
    if (status != PSA_SUCCESS)
        return (status);
    /* Breaking up a request into smaller chunks is currently not supported
     * for the extrernal RNG interface. */
    if (output_length != output_size)
        return (PSA_ERROR_INSUFFICIENT_ENTROPY);
    return (PSA_SUCCESS);

#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */

    while (output_size > 0) {
        size_t request_size =
            (output_size > MBEDTLS_PSA_RANDOM_MAX_REQUEST ?
             MBEDTLS_PSA_RANDOM_MAX_REQUEST :
             output_size);
        int ret = mbedtls_psa_get_random(MBEDTLS_PSA_RANDOM_STATE,
                                         output, request_size);
        if (ret != 0)
            return (mbedtls_to_psa_error(ret));
        output_size -= request_size;
        output += request_size;
    }
    return (PSA_SUCCESS);
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}

/* Wrapper function allowing the classic API to use the PSA RNG.
 *
 * `mbedtls_psa_get_random(MBEDTLS_PSA_RANDOM_STATE, ...)` calls
 * `psa_generate_random(...)`. The state parameter is ignored since the
 * PSA API doesn't support passing an explicit state.
 *
 * In the non-external case, psa_generate_random() calls an
 * `mbedtls_xxx_drbg_random` function which has exactly the same signature
 * and semantics as mbedtls_psa_get_random(). As an optimization,
 * instead of doing this back-and-forth between the PSA API and the
 * classic API, psa_crypto_random_impl.h defines `mbedtls_psa_get_random`
 * as a constant function pointer to `mbedtls_xxx_drbg_random`.
 */
#if defined (MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
int mbedtls_psa_get_random(void *p_rng,
                           unsigned char *output,
                           size_t output_size) {
    /* This function takes a pointer to the RNG state because that's what
     * classic mbedtls functions using an RNG expect. The PSA RNG manages
     * its own state internally and doesn't let the caller access that state.
     * So we just ignore the state parameter, and in practice we'll pass
     * NULL. */
    (void) p_rng;
    psa_status_t status = psa_generate_random(output, output_size);
    if (status == PSA_SUCCESS)
        return (0);
    else
        return (MBEDTLS_ERR_ENTROPY_SOURCE_FAILED);
}
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */

#if defined(MBEDTLS_PSA_INJECT_ENTROPY)
#include "mbedtls/entropy_poll.h"

psa_status_t mbedtls_psa_inject_entropy(const uint8_t *seed,
                                        size_t seed_size) {
    if (global_data.initialized)
        return (PSA_ERROR_NOT_PERMITTED);

    if (((seed_size < MBEDTLS_ENTROPY_MIN_PLATFORM) ||
            (seed_size < MBEDTLS_ENTROPY_BLOCK_SIZE)) ||
            (seed_size > MBEDTLS_ENTROPY_MAX_SEED_SIZE))
        return (PSA_ERROR_INVALID_ARGUMENT);

    return (mbedtls_psa_storage_inject_entropy(seed, seed_size));
}
#endif /* MBEDTLS_PSA_INJECT_ENTROPY */

/** Validate the key type and size for key generation
 *
 * \param  type  The key type
 * \param  bits  The number of bits of the key
 *
 * \retval #PSA_SUCCESS
 *         The key type and size are valid.
 * \retval #PSA_ERROR_INVALID_ARGUMENT
 *         The size in bits of the key is not valid.
 * \retval #PSA_ERROR_NOT_SUPPORTED
 *         The type and/or the size in bits of the key or the combination of
 *         the two is not supported.
 */
static psa_status_t psa_validate_key_type_and_size_for_key_generation(
    psa_key_type_t type, size_t bits) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;

    if (key_type_is_raw_bytes(type)) {
        status = validate_unstructured_key_bit_size(type, bits);
        if (status != PSA_SUCCESS)
            return (status);
    } else
#if defined(PSA_WANT_KEY_TYPE_RSA_KEY_PAIR)
        if (PSA_KEY_TYPE_IS_RSA(type) && PSA_KEY_TYPE_IS_KEY_PAIR(type)) {
            if (bits > PSA_VENDOR_RSA_MAX_KEY_BITS)
                return (PSA_ERROR_NOT_SUPPORTED);

            /* Accept only byte-aligned keys, for the same reasons as
             * in psa_import_rsa_key(). */
            if (bits % 8 != 0)
                return (PSA_ERROR_NOT_SUPPORTED);
        } else
#endif /* defined(PSA_WANT_KEY_TYPE_RSA_KEY_PAIR) */

#if defined(PSA_WANT_KEY_TYPE_ECC_KEY_PAIR)
            if (PSA_KEY_TYPE_IS_ECC(type) && PSA_KEY_TYPE_IS_KEY_PAIR(type)) {
                /* To avoid empty block, return successfully here. */
                return (PSA_SUCCESS);
            } else
#endif /* defined(PSA_WANT_KEY_TYPE_ECC_KEY_PAIR) */
            {
                return (PSA_ERROR_NOT_SUPPORTED);
            }

    return (PSA_SUCCESS);
}

psa_status_t psa_generate_key_internal(
    const psa_key_attributes_t *attributes,
    uint8_t *key_buffer, size_t key_buffer_size, size_t *key_buffer_length) {
    psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
    psa_key_type_t type = attributes->core.type;

    if ((attributes->domain_parameters == NULL) &&
            (attributes->domain_parameters_size != 0))
        return (PSA_ERROR_INVALID_ARGUMENT);

    if (key_type_is_raw_bytes(type)) {
        status = psa_generate_random(key_buffer, key_buffer_size);
        if (status != PSA_SUCCESS)
            return (status);

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES)
        if (type == PSA_KEY_TYPE_DES)
            psa_des_set_key_parity(key_buffer, key_buffer_size);
#endif /* MBEDTLS_PSA_BUILTIN_KEY_TYPE_DES */
    } else

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR)
        if (type == PSA_KEY_TYPE_RSA_KEY_PAIR) {
            return (mbedtls_psa_rsa_generate_key(attributes,
                                                 key_buffer,
                                                 key_buffer_size,
                                                 key_buffer_length));
        } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR) */

#if defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR)
            if (PSA_KEY_TYPE_IS_ECC(type) && PSA_KEY_TYPE_IS_KEY_PAIR(type)) {
                return (mbedtls_psa_ecp_generate_key(attributes,
                                                     key_buffer,
                                                     key_buffer_size,
                                                     key_buffer_length));
            } else
#endif /* defined(MBEDTLS_PSA_BUILTIN_KEY_TYPE_ECC_KEY_PAIR) */
            {
                (void)key_buffer_length;
                return (PSA_ERROR_NOT_SUPPORTED);
            }

    return (PSA_SUCCESS);
}

psa_status_t psa_generate_key(const psa_key_attributes_t *attributes,
                              mbedtls_svc_key_id_t *key) {
    psa_status_t status;
    psa_key_slot_t *slot = NULL;
    psa_se_drv_table_entry_t *driver = NULL;
    size_t key_buffer_size;

    *key = MBEDTLS_SVC_KEY_ID_INIT;

    /* Reject any attempt to create a zero-length key so that we don't
     * risk tripping up later, e.g. on a malloc(0) that returns NULL. */
    if (psa_get_key_bits(attributes) == 0)
        return (PSA_ERROR_INVALID_ARGUMENT);

    status = psa_start_key_creation(PSA_KEY_CREATION_GENERATE, attributes,
                                    &slot, &driver);
    if (status != PSA_SUCCESS)
        goto exit;

    /* In the case of a transparent key or an opaque key stored in local
     * storage (thus not in the case of generating a key in a secure element
     * or cryptoprocessor with storage), we have to allocate a buffer to
     * hold the generated key material. */
    if (slot->key.data == NULL) {
        if (PSA_KEY_LIFETIME_GET_LOCATION(attributes->core.lifetime) ==
                PSA_KEY_LOCATION_LOCAL_STORAGE) {
            status = psa_validate_key_type_and_size_for_key_generation(
                         attributes->core.type, attributes->core.bits);
            if (status != PSA_SUCCESS)
                goto exit;

            key_buffer_size = PSA_EXPORT_KEY_OUTPUT_SIZE(
                                  attributes->core.type,
                                  attributes->core.bits);
        } else {
            status = psa_driver_wrapper_get_key_buffer_size(
                         attributes, &key_buffer_size);
            if (status != PSA_SUCCESS)
                goto exit;
        }

        status = psa_allocate_buffer_to_slot(slot, key_buffer_size);
        if (status != PSA_SUCCESS)
            goto exit;
    }

    status = psa_driver_wrapper_generate_key(attributes,
                                             slot->key.data, slot->key.bytes, &slot->key.bytes);

    if (status != PSA_SUCCESS)
        psa_remove_key_data_from_memory(slot);

exit:
    if (status == PSA_SUCCESS)
        status = psa_finish_key_creation(slot, driver, key);
    if (status != PSA_SUCCESS)
        psa_fail_key_creation(slot, driver);

    return (status);
}

/****************************************************************/
/* Module setup */
/****************************************************************/

#if !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
psa_status_t mbedtls_psa_crypto_configure_entropy_sources(
    void (* entropy_init)(mbedtls_entropy_context *ctx),
    void (* entropy_free)(mbedtls_entropy_context *ctx)) {
    if (global_data.rng_state != RNG_NOT_INITIALIZED)
        return (PSA_ERROR_BAD_STATE);
    global_data.rng.entropy_init = entropy_init;
    global_data.rng.entropy_free = entropy_free;
    return (PSA_SUCCESS);
}
#endif /* !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) */

void mbedtls_psa_crypto_free(void) {
    psa_wipe_all_key_slots();
    if (global_data.rng_state != RNG_NOT_INITIALIZED) {
        mbedtls_psa_random_free(&global_data.rng);
    }
    /* Wipe all remaining data, including configuration.
     * In particular, this sets all state indicator to the value
     * indicating "uninitialized". */
    mbedtls_platform_zeroize(&global_data, sizeof(global_data));
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    /* Unregister all secure element drivers, so that we restart from
     * a pristine state. */
    psa_unregister_all_se_drivers();
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
}

#if defined(PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS)
/** Recover a transaction that was interrupted by a power failure.
 *
 * This function is called during initialization, before psa_crypto_init()
 * returns. If this function returns a failure status, the initialization
 * fails.
 */
static psa_status_t psa_crypto_recover_transaction(
    const psa_crypto_transaction_t *transaction) {
    switch (transaction->unknown.type) {
        case PSA_CRYPTO_TRANSACTION_CREATE_KEY:
        case PSA_CRYPTO_TRANSACTION_DESTROY_KEY:
        /* TODO - fall through to the failure case until this
         * is implemented.
         * https://github.com/ARMmbed/mbed-crypto/issues/218
         */
        default:
            /* We found an unsupported transaction in the storage.
             * We don't know what state the storage is in. Give up. */
            return (PSA_ERROR_DATA_INVALID);
    }
}
#endif /* PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS */

psa_status_t psa_crypto_init(void) {
    psa_status_t status;

    /* Double initialization is explicitly allowed. */
    if (global_data.initialized != 0)
        return (PSA_SUCCESS);

    /* Initialize and seed the random generator. */
    mbedtls_psa_random_init(&global_data.rng);
    global_data.rng_state = RNG_INITIALIZED;
    status = mbedtls_psa_random_seed(&global_data.rng);
    if (status != PSA_SUCCESS)
        goto exit;
    global_data.rng_state = RNG_SEEDED;

    status = psa_initialize_key_slots();
    if (status != PSA_SUCCESS)
        goto exit;

#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
    status = psa_init_all_se_drivers();
    if (status != PSA_SUCCESS)
        goto exit;
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */

#if defined(PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS)
    status = psa_crypto_load_transaction();
    if (status == PSA_SUCCESS) {
        status = psa_crypto_recover_transaction(&psa_crypto_transaction);
        if (status != PSA_SUCCESS)
            goto exit;
        status = psa_crypto_stop_transaction();
    } else if (status == PSA_ERROR_DOES_NOT_EXIST) {
        /* There's no transaction to complete. It's all good. */
        status = PSA_SUCCESS;
    }
#endif /* PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS */

    /* All done. */
    global_data.initialized = 1;

exit:
    if (status != PSA_SUCCESS)
        mbedtls_psa_crypto_free();
    return (status);
}

#endif /* MBEDTLS_PSA_CRYPTO_C */