1 /* dtls -- a very basic DTLS implementation
2 *
3 * Copyright (C) 2011--2012 Olaf Bergmann <bergmann@tzi.org>
4 *
5 * Permission is hereby granted, free of charge, to any person
6 * obtaining a copy of this software and associated documentation
7 * files (the "Software"), to deal in the Software without
8 * restriction, including without limitation the rights to use, copy,
9 * modify, merge, publish, distribute, sublicense, and/or sell copies
10 * of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be
14 * included in all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
20 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
21 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE.
24 */
25
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <string.h>
29
30 #include "dtls_config.h"
31
32 #ifdef HAVE_ASSERT_H
33 #include <assert.h>
34 #else
35 #define assert(x)
36 #endif
37
38 #include "debug.h"
39 #include "hmac.h"
40
41 /* use malloc()/free() on platforms other than Contiki */
42 #ifndef WITH_CONTIKI
43 #include <stdlib.h>
44
45 static inline dtls_hmac_context_t *
dtls_hmac_context_new()46 dtls_hmac_context_new() {
47 return (dtls_hmac_context_t *)malloc(sizeof(dtls_hmac_context_t));
48 }
49
50 static inline void
dtls_hmac_context_free(dtls_hmac_context_t * ctx)51 dtls_hmac_context_free(dtls_hmac_context_t *ctx) {
52 free(ctx);
53 }
54
55 #else /* WITH_CONTIKI */
56 #include "memb.h"
57 MEMB(hmac_context_storage, dtls_hmac_context_t, DTLS_HASH_MAX);
58
59 static inline dtls_hmac_context_t *
dtls_hmac_context_new()60 dtls_hmac_context_new() {
61 return (dtls_hmac_context_t *)memb_alloc(&hmac_context_storage);
62 }
63
64 static inline void
dtls_hmac_context_free(dtls_hmac_context_t * ctx)65 dtls_hmac_context_free(dtls_hmac_context_t *ctx) {
66 memb_free(&hmac_context_storage, ctx);
67 }
68
69 void
dtls_hmac_storage_init()70 dtls_hmac_storage_init() {
71 memb_init(&hmac_context_storage);
72 }
73 #endif /* WITH_CONTIKI */
74
75 void
dtls_hmac_update(dtls_hmac_context_t * ctx,const unsigned char * input,size_t ilen)76 dtls_hmac_update(dtls_hmac_context_t *ctx,
77 const unsigned char *input, size_t ilen) {
78 assert(ctx);
79 dtls_hash_update(&ctx->data, input, ilen);
80 }
81
82 dtls_hmac_context_t *
dtls_hmac_new(const unsigned char * key,size_t klen)83 dtls_hmac_new(const unsigned char *key, size_t klen) {
84 dtls_hmac_context_t *ctx;
85
86 ctx = dtls_hmac_context_new();
87 if (ctx)
88 dtls_hmac_init(ctx, key, klen);
89
90 return ctx;
91 }
92
93 void
dtls_hmac_init(dtls_hmac_context_t * ctx,const unsigned char * key,size_t klen)94 dtls_hmac_init(dtls_hmac_context_t *ctx, const unsigned char *key, size_t klen) {
95 int i;
96
97 assert(ctx);
98
99 memset(ctx, 0, sizeof(dtls_hmac_context_t));
100
101 if (klen > DTLS_HMAC_BLOCKSIZE) {
102 dtls_hash_init(&ctx->data);
103 dtls_hash_update(&ctx->data, key, klen);
104 dtls_hash_finalize(ctx->pad, &ctx->data);
105 } else
106 memcpy(ctx->pad, key, klen);
107
108 /* create ipad: */
109 for (i=0; i < DTLS_HMAC_BLOCKSIZE; ++i)
110 ctx->pad[i] ^= 0x36;
111
112 dtls_hash_init(&ctx->data);
113 dtls_hmac_update(ctx, ctx->pad, DTLS_HMAC_BLOCKSIZE);
114
115 /* create opad by xor-ing pad[i] with 0x36 ^ 0x5C: */
116 for (i=0; i < DTLS_HMAC_BLOCKSIZE; ++i)
117 ctx->pad[i] ^= 0x6A;
118 }
119
120 void
dtls_hmac_free(dtls_hmac_context_t * ctx)121 dtls_hmac_free(dtls_hmac_context_t *ctx) {
122 if (ctx)
123 dtls_hmac_context_free(ctx);
124 }
125
126 int
dtls_hmac_finalize(dtls_hmac_context_t * ctx,unsigned char * result)127 dtls_hmac_finalize(dtls_hmac_context_t *ctx, unsigned char *result) {
128 unsigned char buf[DTLS_HMAC_DIGEST_SIZE];
129 size_t len;
130
131 assert(ctx);
132 assert(result);
133
134 len = dtls_hash_finalize(buf, &ctx->data);
135
136 dtls_hash_init(&ctx->data);
137 dtls_hash_update(&ctx->data, ctx->pad, DTLS_HMAC_BLOCKSIZE);
138 dtls_hash_update(&ctx->data, buf, len);
139
140 len = dtls_hash_finalize(result, &ctx->data);
141
142 return len;
143 }
144
145 #ifdef HMAC_TEST
146 #include <stdio.h>
147
main(int argc,char ** argv)148 int main(int argc, char **argv) {
149 static unsigned char buf[DTLS_HMAC_DIGEST_SIZE];
150 size_t len, i;
151 dtls_hmac_context_t *ctx;
152
153 if (argc < 3) {
154 fprintf(stderr, "usage: %s key text", argv[0]);
155 return -1;
156 }
157
158 dtls_hmac_storage_init();
159 ctx = dtls_hmac_new(argv[1], strlen(argv[1]));
160 assert(ctx);
161 dtls_hmac_update(ctx, argv[2], strlen(argv[2]));
162
163 len = dtls_hmac_finalize(ctx, buf);
164
165 for(i = 0; i < len; i++)
166 printf("%02x", buf[i]);
167 printf("\n");
168
169 dtls_hmac_free(ctx);
170
171 return 0;
172 }
173 #endif
174
