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 <asm/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         tmp.page = virt_to_page(key);
  29         tmp.offset = ((long)key & ~PAGE_MASK);
  30         tmp.length = keylen;
  31         crypto_digest_digest(tfm, &tmp, 1, key);
  32
  33 }
  34
  35 int crypto_alloc_hmac_block(struct crypto_tfm *tfm)
  36 {
  37         int ret = 0;
  38
  39         BUG_ON(!crypto_tfm_alg_blocksize(tfm));
  40
  41         tfm->crt_digest.dit_hmac_block = kmalloc(crypto_tfm_alg_blocksize(tfm),
  42                                                  GFP_KERNEL);
  43         if (tfm->crt_digest.dit_hmac_block == NULL)
  44                 ret = -ENOMEM;
  45
  46         return ret;
  47
  48 }
  49
  50 void crypto_free_hmac_block(struct crypto_tfm *tfm)
  51 {
  52         if (tfm->crt_digest.dit_hmac_block)
  53                 kfree(tfm->crt_digest.dit_hmac_block);
  54 }
  55
  56 void crypto_hmac_init(struct crypto_tfm *tfm, u8 *key, unsigned int *keylen)
  57 {
  58         unsigned int i;
  59         struct scatterlist tmp;
  60         char *ipad = tfm->crt_digest.dit_hmac_block;
  61
  62         if (*keylen > crypto_tfm_alg_blocksize(tfm)) {
  63                 hash_key(tfm, key, *keylen);
  64                 *keylen = crypto_tfm_alg_digestsize(tfm);
  65         }
  66
  67         memset(ipad, 0, crypto_tfm_alg_blocksize(tfm));
  68         memcpy(ipad, key, *keylen);
  69
  70         for (i = 0; i < crypto_tfm_alg_blocksize(tfm); i++)
  71                 ipad[i] ^= 0x36;
  72
  73         tmp.page = virt_to_page(ipad);
  74         tmp.offset = ((long)ipad & ~PAGE_MASK);
  75         tmp.length = crypto_tfm_alg_blocksize(tfm);
  76
  77         crypto_digest_init(tfm);
  78         crypto_digest_update(tfm, &tmp, 1);
  79 }
  80
  81 void crypto_hmac_update(struct crypto_tfm *tfm,
  82                         struct scatterlist *sg, unsigned int nsg)
  83 {
  84         crypto_digest_update(tfm, sg, nsg);
  85 }
  86
  87 void crypto_hmac_final(struct crypto_tfm *tfm, u8 *key,
  88                        unsigned int *keylen, u8 *out)
  89 {
  90         unsigned int i;
  91         struct scatterlist tmp;
  92         char *opad = tfm->crt_digest.dit_hmac_block;
  93
  94         if (*keylen > crypto_tfm_alg_blocksize(tfm)) {
  95                 hash_key(tfm, key, *keylen);
  96                 *keylen = crypto_tfm_alg_digestsize(tfm);
  97         }
  98
  99         crypto_digest_final(tfm, out);
 100
 101         memset(opad, 0, crypto_tfm_alg_blocksize(tfm));
 102         memcpy(opad, key, *keylen);
 103
 104         for (i = 0; i < crypto_tfm_alg_blocksize(tfm); i++)
 105                 opad[i] ^= 0x5c;
 106
 107         tmp.page = virt_to_page(opad);
 108         tmp.offset = ((long)opad & ~PAGE_MASK);
 109         tmp.length = crypto_tfm_alg_blocksize(tfm);
 110
 111         crypto_digest_init(tfm);
 112         crypto_digest_update(tfm, &tmp, 1);
 113
 114         tmp.page = virt_to_page(out);
 115         tmp.offset = ((long)out & ~PAGE_MASK);
 116         tmp.length = crypto_tfm_alg_digestsize(tfm);
 117
 118         crypto_digest_update(tfm, &tmp, 1);
 119         crypto_digest_final(tfm, out);
 120 }
 121
 122 void crypto_hmac(struct crypto_tfm *tfm, u8 *key, unsigned int *keylen,
 123                  struct scatterlist *sg, unsigned int nsg, u8 *out)
 124 {
 125         crypto_hmac_init(tfm, key, keylen);
 126         crypto_hmac_update(tfm, sg, nsg);
 127         crypto_hmac_final(tfm, key, keylen, out);
 128 }
 129
 130 EXPORT_SYMBOL_GPL(crypto_hmac_init);
 131 EXPORT_SYMBOL_GPL(crypto_hmac_update);
 132 EXPORT_SYMBOL_GPL(crypto_hmac_final);
 133 EXPORT_SYMBOL_GPL(crypto_hmac);
 134