include/crypto/xts.h

   1 #ifndef _CRYPTO_XTS_H
   2 #define _CRYPTO_XTS_H
   3
   4 #include <crypto/b128ops.h>
   5 #include <crypto/internal/skcipher.h>
   6 #include <linux/fips.h>
   7
   8 struct scatterlist;
   9 struct blkcipher_desc;
  10
  11 #define XTS_BLOCK_SIZE 16
  12
  13 struct xts_crypt_req {
  14         le128 *tbuf;
  15         unsigned int tbuflen;
  16
  17         void *tweak_ctx;
  18         void (*tweak_fn)(void *ctx, u8* dst, const u8* src);
  19         void *crypt_ctx;
  20         void (*crypt_fn)(void *ctx, u8 *blks, unsigned int nbytes);
  21 };
  22
  23 #define XTS_TWEAK_CAST(x) ((void (*)(void *, u8*, const u8*))(x))
  24
  25 int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
  26               struct scatterlist *src, unsigned int nbytes,
  27               struct xts_crypt_req *req);
  28
  29 static inline int xts_check_key(struct crypto_tfm *tfm,
  30                                 const u8 *key, unsigned int keylen)
  31 {
  32         u32 *flags = &tfm->crt_flags;
  33
  34         /*
  35          * key consists of keys of equal size concatenated, therefore
  36          * the length must be even.
  37          */
  38         if (keylen % 2) {
  39                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
  40                 return -EINVAL;
  41         }
  42
  43         /* ensure that the AES and tweak key are not identical */
  44         if (fips_enabled &&
  45             !crypto_memneq(key, key + (keylen / 2), keylen / 2)) {
  46                 *flags |= CRYPTO_TFM_RES_WEAK_KEY;
  47                 return -EINVAL;
  48         }
  49
  50         return 0;
  51 }
  52
  53 static inline int xts_verify_key(struct crypto_skcipher *tfm,
  54                                  const u8 *key, unsigned int keylen)
  55 {
  56         /*
  57          * key consists of keys of equal size concatenated, therefore
  58          * the length must be even.
  59          */
  60         if (keylen % 2) {
  61                 crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
  62                 return -EINVAL;
  63         }
  64
  65         /* ensure that the AES and tweak key are not identical */
  66         if ((fips_enabled || crypto_skcipher_get_flags(tfm) &
  67                              CRYPTO_TFM_REQ_WEAK_KEY) &&
  68             !crypto_memneq(key, key + (keylen / 2), keylen / 2)) {
  69                 crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_WEAK_KEY);
  70                 return -EINVAL;
  71         }
  72
  73         return 0;
  74 }
  75
  76 #endif  /* _CRYPTO_XTS_H */