lavu: Add an API for calculating HMAC (RFC 2104)
[libav.git] / 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 }