LXR linux/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
  13static 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
  37static 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_FORBID_WEAK_KEYS)) &&
  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 */
  61