libavutil/hmac.c

   1 /*
   2  * Copyright (C) 2012 Martin Storsjo
   3  *
   4  * This file is part of Libav.
   5  *
   6  * Libav is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * Libav is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with Libav; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include <string.h>
  22
  23 #include "hmac.h"
  24 #include "md5.h"
  25 #include "sha.h"
  26 #include "mem.h"
  27
  28 #define MAX_HASHLEN 20
  29 #define MAX_BLOCKLEN 64
  30
  31 struct AVHMAC {
  32     void *hash;
  33     int blocklen, hashlen;
  34     void (*final)(void*, uint8_t*);
  35     void (*update)(void*, const uint8_t*, int len);
  36     void (*init)(void*);
  37     uint8_t key[MAX_BLOCKLEN];
  38     int keylen;
  39 };
  40
  41 static void sha1_init(void *ctx)
  42 {
  43     av_sha_init(ctx, 160);
  44 }
  45
  46 AVHMAC *av_hmac_alloc(enum AVHMACType type)
  47 {
  48     AVHMAC *c = av_mallocz(sizeof(*c));
  49     if (!c)
  50         return NULL;
  51     switch (type) {
  52     case AV_HMAC_MD5:
  53         c->blocklen = 64;
  54         c->hashlen  = 16;
  55         c->init     = av_md5_init;
  56         c->update   = av_md5_update;
  57         c->final    = av_md5_final;
  58         c->hash     = av_md5_alloc();
  59         break;
  60     case AV_HMAC_SHA1:
  61         c->blocklen = 64;
  62         c->hashlen  = 20;
  63         c->init     = sha1_init;
  64         c->update   = av_sha_update;
  65         c->final    = av_sha_final;
  66         c->hash     = av_sha_alloc();
  67         break;
  68     default:
  69         av_free(c);
  70         return NULL;
  71     }
  72     if (!c->hash) {
  73         av_free(c);
  74         return NULL;
  75     }
  76     return c;
  77 }
  78
  79 void av_hmac_free(AVHMAC *c)
  80 {
  81     if (!c)
  82         return;
  83     av_free(c->hash);
  84     av_free(c);
  85 }
  86
  87 void av_hmac_init(AVHMAC *c, const uint8_t *key, unsigned int keylen)
  88 {
  89     int i;
  90     uint8_t block[MAX_BLOCKLEN];
  91     if (keylen > c->blocklen) {
  92         c->init(c->hash);
  93         c->update(c->hash, key, keylen);
  94         c->final(c->hash, c->key);
  95         c->keylen = c->hashlen;
  96     } else {
  97         memcpy(c->key, key, keylen);
  98         c->keylen = keylen;
  99     }
 100     c->init(c->hash);
 101     for (i = 0; i < c->keylen; i++)
 102         block[i] = c->key[i] ^ 0x36;
 103     for (i = c->keylen; i < c->blocklen; i++)
 104         block[i] = 0x36;
 105     c->update(c->hash, block, c->blocklen);
 106 }
 107
 108 void av_hmac_update(AVHMAC *c, const uint8_t *data, unsigned int len)
 109 {
 110     c->update(c->hash, data, len);
 111 }
 112
 113 int av_hmac_final(AVHMAC *c, uint8_t *out, unsigned int outlen)
 114 {
 115     uint8_t block[MAX_BLOCKLEN];
 116     int i;
 117     if (outlen < c->hashlen)
 118         return AVERROR(EINVAL);
 119     c->final(c->hash, out);
 120     c->init(c->hash);
 121     for (i = 0; i < c->keylen; i++)
 122         block[i] = c->key[i] ^ 0x5C;
 123     for (i = c->keylen; i < c->blocklen; i++)
 124         block[i] = 0x5C;
 125     c->update(c->hash, block, c->blocklen);
 126     c->update(c->hash, out, c->hashlen);
 127     c->final(c->hash, out);
 128     return c->hashlen;
 129 }
 130
 131 int av_hmac_calc(AVHMAC *c, const uint8_t *data, unsigned int len,
 132                  const uint8_t *key, unsigned int keylen,
 133                  uint8_t *out, unsigned int outlen)
 134 {
 135     av_hmac_init(c, key, keylen);
 136     av_hmac_update(c, data, len);
 137     return av_hmac_final(c, out, outlen);
 138 }