crypto/hmac.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
   5  *
   6  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
   7  *
   8  * The HMAC implementation is derived from USAGI.
   9  * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI
  10  *
  11  * This program is free software; you can redistribute it and/or modify it
  12  * under the terms of the GNU General Public License as published by the Free
  13  * Software Foundation; either version 2 of the License, or (at your option)
  14  * any later version.
  15  *
  16  */
  17 #include <linux/crypto.h>
  18 #include <linux/mm.h>
  19 #include <linux/highmem.h>
  20 #include <linux/slab.h>
  21 #include <linux/scatterlist.h>
  22 #include "internal.h"
  23
  24 static void hash_key(struct crypto_tfm *tfm, u8 *key, unsigned int keylen)
  25 {
  26         struct scatterlist tmp;
  27
  28         sg_set_buf(&tmp, key, keylen);
  29         crypto_digest_digest(tfm, &tmp, 1, key);
  30 }
  31
  32 int crypto_alloc_hmac_block(struct crypto_tfm *tfm)
  33 {
  34         int ret = 0;
  35
  36         BUG_ON(!crypto_tfm_alg_blocksize(tfm));
  37
  38         tfm->crt_digest.dit_hmac_block = kmalloc(crypto_tfm_alg_blocksize(tfm),
  39                                                  GFP_KERNEL);
  40         if (tfm->crt_digest.dit_hmac_block == NULL)
  41                 ret = -ENOMEM;
  42
  43         return ret;
  44
  45 }
  46
  47 void crypto_free_hmac_block(struct crypto_tfm *tfm)
  48 {
  49         kfree(tfm->crt_digest.dit_hmac_block);
  50 }
  51
  52 void crypto_hmac_init(struct crypto_tfm *tfm, u8 *key, unsigned int *keylen)
  53 {
  54         unsigned int i;
  55         struct scatterlist tmp;
  56         char *ipad = tfm->crt_digest.dit_hmac_block;
  57
  58         if (*keylen > crypto_tfm_alg_blocksize(tfm)) {
  59                 hash_key(tfm, key, *keylen);
  60                 *keylen = crypto_tfm_alg_digestsize(tfm);
  61         }
  62
  63         memset(ipad, 0, crypto_tfm_alg_blocksize(tfm));
  64         memcpy(ipad, key, *keylen);
  65
  66         for (i = 0; i < crypto_tfm_alg_blocksize(tfm); i++)
  67                 ipad[i] ^= 0x36;
  68
  69         sg_set_buf(&tmp, ipad, crypto_tfm_alg_blocksize(tfm));
  70
  71         crypto_digest_init(tfm);
  72         crypto_digest_update(tfm, &tmp, 1);
  73 }
  74
  75 void crypto_hmac_update(struct crypto_tfm *tfm,
  76                         struct scatterlist *sg, unsigned int nsg)
  77 {
  78         crypto_digest_update(tfm, sg, nsg);
  79 }
  80
  81 void crypto_hmac_final(struct crypto_tfm *tfm, u8 *key,
  82                        unsigned int *keylen, u8 *out)
  83 {
  84         unsigned int i;
  85         struct scatterlist tmp;
  86         char *opad = tfm->crt_digest.dit_hmac_block;
  87
  88         if (*keylen > crypto_tfm_alg_blocksize(tfm)) {
  89                 hash_key(tfm, key, *keylen);
  90                 *keylen = crypto_tfm_alg_digestsize(tfm);
  91         }
  92
  93         crypto_digest_final(tfm, out);
  94
  95         memset(opad, 0, crypto_tfm_alg_blocksize(tfm));
  96         memcpy(opad, key, *keylen);
  97
  98         for (i = 0; i < crypto_tfm_alg_blocksize(tfm); i++)
  99                 opad[i] ^= 0x5c;
 100
 101         sg_set_buf(&tmp, opad, crypto_tfm_alg_blocksize(tfm));
 102
 103         crypto_digest_init(tfm);
 104         crypto_digest_update(tfm, &tmp, 1);
 105
 106         sg_set_buf(&tmp, out, crypto_tfm_alg_digestsize(tfm));
 107
 108         crypto_digest_update(tfm, &tmp, 1);
 109         crypto_digest_final(tfm, out);
 110 }
 111
 112 void crypto_hmac(struct crypto_tfm *tfm, u8 *key, unsigned int *keylen,
 113                  struct scatterlist *sg, unsigned int nsg, u8 *out)
 114 {
 115         crypto_hmac_init(tfm, key, keylen);
 116         crypto_hmac_update(tfm, sg, nsg);
 117         crypto_hmac_final(tfm, key, keylen, out);
 118 }
 119
 120 EXPORT_SYMBOL_GPL(crypto_hmac_init);
 121 EXPORT_SYMBOL_GPL(crypto_hmac_update);
 122 EXPORT_SYMBOL_GPL(crypto_hmac_final);
 123 EXPORT_SYMBOL_GPL(crypto_hmac);
 124