include/crypto/internal/des.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * DES & Triple DES EDE key verification helpers
   4  */
   5
   6 #ifndef __CRYPTO_INTERNAL_DES_H
   7 #define __CRYPTO_INTERNAL_DES_H
   8
   9 #include <linux/crypto.h>
  10 #include <linux/fips.h>
  11 #include <crypto/des.h>
  12 #include <crypto/aead.h>
  13 #include <crypto/skcipher.h>
  14
  15 /**
  16  * crypto_des_verify_key - Check whether a DES key is weak
  17  * @tfm: the crypto algo
  18  * @key: the key buffer
  19  *
  20  * Returns -EINVAL if the key is weak and the crypto TFM does not permit weak
  21  * keys. Otherwise, 0 is returned.
  22  *
  23  * It is the job of the caller to ensure that the size of the key equals
  24  * DES_KEY_SIZE.
  25  */
  26 static inline int crypto_des_verify_key(struct crypto_tfm *tfm, const u8 *key)
  27 {
  28         struct des_ctx tmp;
  29         int err;
  30
  31         err = des_expand_key(&tmp, key, DES_KEY_SIZE);
  32         if (err == -ENOKEY) {
  33                 if (crypto_tfm_get_flags(tfm) & CRYPTO_TFM_REQ_FORBID_WEAK_KEYS)
  34                         err = -EINVAL;
  35                 else
  36                         err = 0;
  37         }
  38         memzero_explicit(&tmp, sizeof(tmp));
  39         return err;
  40 }
  41
  42 /*
  43  * RFC2451:
  44  *
  45  *   For DES-EDE3, there is no known need to reject weak or
  46  *   complementation keys.  Any weakness is obviated by the use of
  47  *   multiple keys.
  48  *
  49  *   However, if the first two or last two independent 64-bit keys are
  50  *   equal (k1 == k2 or k2 == k3), then the DES3 operation is simply the
  51  *   same as DES.  Implementers MUST reject keys that exhibit this
  52  *   property.
  53  *
  54  */
  55 static inline int des3_ede_verify_key(const u8 *key, unsigned int key_len,
  56                                       bool check_weak)
  57 {
  58         int ret = fips_enabled ? -EINVAL : -ENOKEY;
  59         u32 K[6];
  60
  61         memcpy(K, key, DES3_EDE_KEY_SIZE);
  62
  63         if ((!((K[0] ^ K[2]) | (K[1] ^ K[3])) ||
  64              !((K[2] ^ K[4]) | (K[3] ^ K[5]))) &&
  65             (fips_enabled || check_weak))
  66                 goto bad;
  67
  68         if ((!((K[0] ^ K[4]) | (K[1] ^ K[5]))) && fips_enabled)
  69                 goto bad;
  70
  71         ret = 0;
  72 bad:
  73         memzero_explicit(K, DES3_EDE_KEY_SIZE);
  74
  75         return ret;
  76 }
  77
  78 /**
  79  * crypto_des3_ede_verify_key - Check whether a DES3-EDE key is weak
  80  * @tfm: the crypto algo
  81  * @key: the key buffer
  82  *
  83  * Returns -EINVAL if the key is weak and the crypto TFM does not permit weak
  84  * keys or when running in FIPS mode. Otherwise, 0 is returned. Note that some
  85  * keys are rejected in FIPS mode even if weak keys are permitted by the TFM
  86  * flags.
  87  *
  88  * It is the job of the caller to ensure that the size of the key equals
  89  * DES3_EDE_KEY_SIZE.
  90  */
  91 static inline int crypto_des3_ede_verify_key(struct crypto_tfm *tfm,
  92                                              const u8 *key)
  93 {
  94         return des3_ede_verify_key(key, DES3_EDE_KEY_SIZE,
  95                                    crypto_tfm_get_flags(tfm) &
  96                                    CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
  97 }
  98
  99 static inline int verify_skcipher_des_key(struct crypto_skcipher *tfm,
 100                                           const u8 *key)
 101 {
 102         return crypto_des_verify_key(crypto_skcipher_tfm(tfm), key);
 103 }
 104
 105 static inline int verify_skcipher_des3_key(struct crypto_skcipher *tfm,
 106                                            const u8 *key)
 107 {
 108         return crypto_des3_ede_verify_key(crypto_skcipher_tfm(tfm), key);
 109 }
 110
 111 static inline int verify_aead_des_key(struct crypto_aead *tfm, const u8 *key,
 112                                       int keylen)
 113 {
 114         if (keylen != DES_KEY_SIZE)
 115                 return -EINVAL;
 116         return crypto_des_verify_key(crypto_aead_tfm(tfm), key);
 117 }
 118
 119 static inline int verify_aead_des3_key(struct crypto_aead *tfm, const u8 *key,
 120                                        int keylen)
 121 {
 122         if (keylen != DES3_EDE_KEY_SIZE)
 123                 return -EINVAL;
 124         return crypto_des3_ede_verify_key(crypto_aead_tfm(tfm), key);
 125 }
 126
 127 #endif /* __CRYPTO_INTERNAL_DES_H */