1 /*
2 * hmac.c
3 *
4 * implementation of hmac auth_type_t
5 *
6 * David A. McGrew
7 * Cisco Systems, Inc.
8 */
9 /*
10 *
11 * Copyright(c) 2001-2006 Cisco Systems, Inc.
12 * All rights reserved.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 *
18 * Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 *
21 * Redistributions in binary form must reproduce the above
22 * copyright notice, this list of conditions and the following
23 * disclaimer in the documentation and/or other materials provided
24 * with the distribution.
25 *
26 * Neither the name of the Cisco Systems, Inc. nor the names of its
27 * contributors may be used to endorse or promote products derived
28 * from this software without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
31 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
32 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
33 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
34 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
35 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
36 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
37 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
41 * OF THE POSSIBILITY OF SUCH DAMAGE.
42 *
43 */
44
45 #include "hmac.h"
46 #include "alloc.h"
47
48 /* the debug module for authentiation */
49
50 debug_module_t mod_hmac = {
51 0, /* debugging is off by default */
52 "hmac sha-1" /* printable name for module */
53 };
54
55
56 err_status_t
hmac_alloc(auth_t ** a,int key_len,int out_len)57 hmac_alloc(auth_t **a, int key_len, int out_len) {
58 extern auth_type_t hmac;
59 uint8_t *pointer;
60
61 debug_print(mod_hmac, "allocating auth func with key length %d", key_len);
62 debug_print(mod_hmac, " tag length %d", out_len);
63
64 /*
65 * check key length - note that we don't support keys larger
66 * than 20 bytes yet
67 */
68 if (key_len > 20)
69 return err_status_bad_param;
70
71 /* check output length - should be less than 20 bytes */
72 if (out_len > 20)
73 return err_status_bad_param;
74
75 /* allocate memory for auth and hmac_ctx_t structures */
76 pointer = (uint8_t*)crypto_alloc(sizeof(hmac_ctx_t) + sizeof(auth_t));
77 if (pointer == NULL)
78 return err_status_alloc_fail;
79
80 /* set pointers */
81 *a = (auth_t *)pointer;
82 (*a)->type = &hmac;
83 (*a)->state = pointer + sizeof(auth_t);
84 (*a)->out_len = out_len;
85 (*a)->key_len = key_len;
86 (*a)->prefix_len = 0;
87
88 /* increment global count of all hmac uses */
89 hmac.ref_count++;
90
91 return err_status_ok;
92 }
93
94 err_status_t
hmac_dealloc(auth_t * a)95 hmac_dealloc(auth_t *a) {
96 extern auth_type_t hmac;
97
98 /* zeroize entire state*/
99 octet_string_set_to_zero((uint8_t *)a,
100 sizeof(hmac_ctx_t) + sizeof(auth_t));
101
102 /* free memory */
103 crypto_free(a);
104
105 /* decrement global count of all hmac uses */
106 hmac.ref_count--;
107
108 return err_status_ok;
109 }
110
111 err_status_t
hmac_init(hmac_ctx_t * state,const uint8_t * key,int key_len)112 hmac_init(hmac_ctx_t *state, const uint8_t *key, int key_len) {
113 int i;
114 uint8_t ipad[64];
115
116 /*
117 * check key length - note that we don't support keys larger
118 * than 20 bytes yet
119 */
120 if (key_len > 20)
121 return err_status_bad_param;
122
123 /*
124 * set values of ipad and opad by exoring the key into the
125 * appropriate constant values
126 */
127 for (i=0; i < key_len; i++) {
128 ipad[i] = key[i] ^ 0x36;
129 state->opad[i] = key[i] ^ 0x5c;
130 }
131 /* set the rest of ipad, opad to constant values */
132 for ( ; i < 64; i++) {
133 ipad[i] = 0x36;
134 ((uint8_t *)state->opad)[i] = 0x5c;
135 }
136
137 debug_print(mod_hmac, "ipad: %s", octet_string_hex_string(ipad, 64));
138
139 /* initialize sha1 context */
140 sha1_init(&state->init_ctx);
141
142 /* hash ipad ^ key */
143 sha1_update(&state->init_ctx, ipad, 64);
144 memcpy(&state->ctx, &state->init_ctx, sizeof(sha1_ctx_t));
145
146 return err_status_ok;
147 }
148
149 err_status_t
hmac_start(hmac_ctx_t * state)150 hmac_start(hmac_ctx_t *state) {
151
152 memcpy(&state->ctx, &state->init_ctx, sizeof(sha1_ctx_t));
153
154 return err_status_ok;
155 }
156
157 err_status_t
hmac_update(hmac_ctx_t * state,const uint8_t * message,int msg_octets)158 hmac_update(hmac_ctx_t *state, const uint8_t *message, int msg_octets) {
159
160 debug_print(mod_hmac, "input: %s",
161 octet_string_hex_string(message, msg_octets));
162
163 /* hash message into sha1 context */
164 sha1_update(&state->ctx, message, msg_octets);
165
166 return err_status_ok;
167 }
168
169 err_status_t
hmac_compute(hmac_ctx_t * state,const void * message,int msg_octets,int tag_len,uint8_t * result)170 hmac_compute(hmac_ctx_t *state, const void *message,
171 int msg_octets, int tag_len, uint8_t *result) {
172 uint32_t hash_value[5];
173 uint32_t H[5];
174 int i;
175
176 /* check tag length, return error if we can't provide the value expected */
177 if (tag_len > 20)
178 return err_status_bad_param;
179
180 /* hash message, copy output into H */
181 hmac_update(state, (const uint8_t*)message, msg_octets);
182 sha1_final(&state->ctx, H);
183
184 /*
185 * note that we don't need to debug_print() the input, since the
186 * function hmac_update() already did that for us
187 */
188 debug_print(mod_hmac, "intermediate state: %s",
189 octet_string_hex_string((uint8_t *)H, 20));
190
191 /* re-initialize hash context */
192 sha1_init(&state->ctx);
193
194 /* hash opad ^ key */
195 sha1_update(&state->ctx, (uint8_t *)state->opad, 64);
196
197 /* hash the result of the inner hash */
198 sha1_update(&state->ctx, (uint8_t *)H, 20);
199
200 /* the result is returned in the array hash_value[] */
201 sha1_final(&state->ctx, hash_value);
202
203 /* copy hash_value to *result */
204 for (i=0; i < tag_len; i++)
205 result[i] = ((uint8_t *)hash_value)[i];
206
207 debug_print(mod_hmac, "output: %s",
208 octet_string_hex_string((uint8_t *)hash_value, tag_len));
209
210 return err_status_ok;
211 }
212
213
214 /* begin test case 0 */
215
216 uint8_t
217 hmac_test_case_0_key[20] = {
218 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
219 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
220 0x0b, 0x0b, 0x0b, 0x0b
221 };
222
223 uint8_t
224 hmac_test_case_0_data[8] = {
225 0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65 /* "Hi There" */
226 };
227
228 uint8_t
229 hmac_test_case_0_tag[20] = {
230 0xb6, 0x17, 0x31, 0x86, 0x55, 0x05, 0x72, 0x64,
231 0xe2, 0x8b, 0xc0, 0xb6, 0xfb, 0x37, 0x8c, 0x8e,
232 0xf1, 0x46, 0xbe, 0x00
233 };
234
235 auth_test_case_t
236 hmac_test_case_0 = {
237 20, /* octets in key */
238 hmac_test_case_0_key, /* key */
239 8, /* octets in data */
240 hmac_test_case_0_data, /* data */
241 20, /* octets in tag */
242 hmac_test_case_0_tag, /* tag */
243 NULL /* pointer to next testcase */
244 };
245
246 /* end test case 0 */
247
248 char hmac_description[] = "hmac sha-1 authentication function";
249
250 /*
251 * auth_type_t hmac is the hmac metaobject
252 */
253
254 auth_type_t
255 hmac = {
256 (auth_alloc_func) hmac_alloc,
257 (auth_dealloc_func) hmac_dealloc,
258 (auth_init_func) hmac_init,
259 (auth_compute_func) hmac_compute,
260 (auth_update_func) hmac_update,
261 (auth_start_func) hmac_start,
262 (char *) hmac_description,
263 (int) 0, /* instance count */
264 (auth_test_case_t *) &hmac_test_case_0,
265 (debug_module_t *) &mod_hmac
266 };
267
268