include/crypto/xts.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _CRYPTO_XTS_H
   3 #define _CRYPTO_XTS_H
   4
   5 #include <crypto/b128ops.h>
   6 #include <crypto/internal/skcipher.h>
   7 #include <linux/fips.h>
   8
   9 #define XTS_BLOCK_SIZE 16
  10
  11 #define XTS_TWEAK_CAST(x) ((void (*)(void *, u8*, const u8*))(x))
  12
  13 static inline int xts_check_key(struct crypto_tfm *tfm,
  14                                 const u8 *key, unsigned int keylen)
  15 {
  16         u32 *flags = &tfm->crt_flags;
  17
  18         /*
  19          * key consists of keys of equal size concatenated, therefore
  20          * the length must be even.
  21          */
  22         if (keylen % 2) {
  23                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
  24                 return -EINVAL;
  25         }
  26
  27         /* ensure that the AES and tweak key are not identical */
  28         if (fips_enabled &&
  29             !crypto_memneq(key, key + (keylen / 2), keylen / 2)) {
  30                 *flags |= CRYPTO_TFM_RES_WEAK_KEY;
  31                 return -EINVAL;
  32         }
  33
  34         return 0;
  35 }
  36
  37 static inline int xts_verify_key(struct crypto_skcipher *tfm,
  38                                  const u8 *key, unsigned int keylen)
  39 {
  40         /*
  41          * key consists of keys of equal size concatenated, therefore
  42          * the length must be even.
  43          */
  44         if (keylen % 2) {
  45                 crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  46                 return -EINVAL;
  47         }
  48
  49         /* ensure that the AES and tweak key are not identical */
  50         if ((fips_enabled || crypto_skcipher_get_flags(tfm) &
  51                              CRYPTO_TFM_REQ_WEAK_KEY) &&
  52             !crypto_memneq(key, key + (keylen / 2), keylen / 2)) {
  53                 crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_WEAK_KEY);
  54                 return -EINVAL;
  55         }
  56
  57         return 0;
  58 }
  59
  60 #endif  /* _CRYPTO_XTS_H */