1 /*
2 * hmac_ossl.c
3 *
4 * Implementation of hmac srtp_auth_type_t that leverages OpenSSL
5 *
6 * John A. Foley
7 * Cisco Systems, Inc.
8 */
9 /*
10 *
11 * Copyright(c) 2013-2017, 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 #ifdef HAVE_CONFIG_H
46 #include <config.h>
47 #endif
48
49 #include "auth.h"
50 #include "alloc.h"
51 #include "err.h" /* for srtp_debug */
52 #include <openssl/evp.h>
53 #include <openssl/hmac.h>
54
55 #define SHA1_DIGEST_SIZE 20
56
57 /* the debug module for authentiation */
58
59 srtp_debug_module_t srtp_mod_hmac = {
60 0, /* debugging is off by default */
61 "hmac sha-1 openssl" /* printable name for module */
62 };
63
srtp_hmac_alloc(srtp_auth_t ** a,int key_len,int out_len)64 static srtp_err_status_t srtp_hmac_alloc(srtp_auth_t **a,
65 int key_len,
66 int out_len)
67 {
68 extern const srtp_auth_type_t srtp_hmac;
69
70 debug_print(srtp_mod_hmac, "allocating auth func with key length %d",
71 key_len);
72 debug_print(srtp_mod_hmac, " tag length %d",
73 out_len);
74
75 /* check output length - should be less than 20 bytes */
76 if (out_len > SHA1_DIGEST_SIZE) {
77 return srtp_err_status_bad_param;
78 }
79
80 /* OpenSSL 1.1.0 made HMAC_CTX an opaque structure, which must be allocated
81 using HMAC_CTX_new. But this function doesn't exist in OpenSSL 1.0.x. */
82 #if OPENSSL_VERSION_NUMBER < 0x10100000L || LIBRESSL_VERSION_NUMBER
83 {
84 /* allocate memory for auth and HMAC_CTX structures */
85 uint8_t *pointer;
86 HMAC_CTX *new_hmac_ctx;
87 pointer = (uint8_t *)srtp_crypto_alloc(sizeof(HMAC_CTX) +
88 sizeof(srtp_auth_t));
89 if (pointer == NULL) {
90 return srtp_err_status_alloc_fail;
91 }
92 *a = (srtp_auth_t *)pointer;
93 (*a)->state = pointer + sizeof(srtp_auth_t);
94 new_hmac_ctx = (HMAC_CTX *)((*a)->state);
95
96 HMAC_CTX_init(new_hmac_ctx);
97 }
98
99 #else
100 *a = (srtp_auth_t *)srtp_crypto_alloc(sizeof(srtp_auth_t));
101 if (*a == NULL) {
102 return srtp_err_status_alloc_fail;
103 }
104
105 (*a)->state = HMAC_CTX_new();
106 if ((*a)->state == NULL) {
107 srtp_crypto_free(*a);
108 *a = NULL;
109 return srtp_err_status_alloc_fail;
110 }
111 #endif
112
113 /* set pointers */
114 (*a)->type = &srtp_hmac;
115 (*a)->out_len = out_len;
116 (*a)->key_len = key_len;
117 (*a)->prefix_len = 0;
118
119 return srtp_err_status_ok;
120 }
121
srtp_hmac_dealloc(srtp_auth_t * a)122 static srtp_err_status_t srtp_hmac_dealloc(srtp_auth_t *a)
123 {
124 HMAC_CTX *hmac_ctx;
125
126 hmac_ctx = (HMAC_CTX *)a->state;
127
128 #if OPENSSL_VERSION_NUMBER < 0x10100000L || LIBRESSL_VERSION_NUMBER
129 HMAC_CTX_cleanup(hmac_ctx);
130
131 /* zeroize entire state*/
132 octet_string_set_to_zero(a, sizeof(HMAC_CTX) + sizeof(srtp_auth_t));
133
134 #else
135 HMAC_CTX_free(hmac_ctx);
136
137 /* zeroize entire state*/
138 octet_string_set_to_zero(a, sizeof(srtp_auth_t));
139 #endif
140
141 /* free memory */
142 srtp_crypto_free(a);
143
144 return srtp_err_status_ok;
145 }
146
srtp_hmac_start(void * statev)147 static srtp_err_status_t srtp_hmac_start(void *statev)
148 {
149 HMAC_CTX *state = (HMAC_CTX *)statev;
150
151 if (HMAC_Init_ex(state, NULL, 0, NULL, NULL) == 0)
152 return srtp_err_status_auth_fail;
153
154 return srtp_err_status_ok;
155 }
156
srtp_hmac_init(void * statev,const uint8_t * key,int key_len)157 static srtp_err_status_t srtp_hmac_init(void *statev,
158 const uint8_t *key,
159 int key_len)
160 {
161 HMAC_CTX *state = (HMAC_CTX *)statev;
162
163 if (HMAC_Init_ex(state, key, key_len, EVP_sha1(), NULL) == 0)
164 return srtp_err_status_auth_fail;
165
166 return srtp_err_status_ok;
167 }
168
srtp_hmac_update(void * statev,const uint8_t * message,int msg_octets)169 static srtp_err_status_t srtp_hmac_update(void *statev,
170 const uint8_t *message,
171 int msg_octets)
172 {
173 HMAC_CTX *state = (HMAC_CTX *)statev;
174
175 debug_print(srtp_mod_hmac, "input: %s",
176 srtp_octet_string_hex_string(message, msg_octets));
177
178 if (HMAC_Update(state, message, msg_octets) == 0)
179 return srtp_err_status_auth_fail;
180
181 return srtp_err_status_ok;
182 }
183
srtp_hmac_compute(void * statev,const uint8_t * message,int msg_octets,int tag_len,uint8_t * result)184 static srtp_err_status_t srtp_hmac_compute(void *statev,
185 const uint8_t *message,
186 int msg_octets,
187 int tag_len,
188 uint8_t *result)
189 {
190 HMAC_CTX *state = (HMAC_CTX *)statev;
191 uint8_t hash_value[SHA1_DIGEST_SIZE];
192 int i;
193 unsigned int len;
194
195 /* check tag length, return error if we can't provide the value expected */
196 if (tag_len > SHA1_DIGEST_SIZE) {
197 return srtp_err_status_bad_param;
198 }
199
200 /* hash message, copy output into H */
201 if (HMAC_Update(state, message, msg_octets) == 0)
202 return srtp_err_status_auth_fail;
203
204 if (HMAC_Final(state, hash_value, &len) == 0)
205 return srtp_err_status_auth_fail;
206
207 if (len < tag_len)
208 return srtp_err_status_auth_fail;
209
210 /* copy hash_value to *result */
211 for (i = 0; i < tag_len; i++) {
212 result[i] = hash_value[i];
213 }
214
215 debug_print(srtp_mod_hmac, "output: %s",
216 srtp_octet_string_hex_string(hash_value, tag_len));
217
218 return srtp_err_status_ok;
219 }
220
221 /* begin test case 0 */
222 /* clang-format off */
223 static const uint8_t srtp_hmac_test_case_0_key[SHA1_DIGEST_SIZE] = {
224 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
225 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
226 0x0b, 0x0b, 0x0b, 0x0b
227 };
228 /* clang-format on */
229
230 /* clang-format off */
231 static const uint8_t srtp_hmac_test_case_0_data[8] = {
232 0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65 /* "Hi There" */
233 };
234 /* clang-format on */
235
236 /* clang-format off */
237 static const uint8_t srtp_hmac_test_case_0_tag[SHA1_DIGEST_SIZE] = {
238 0xb6, 0x17, 0x31, 0x86, 0x55, 0x05, 0x72, 0x64,
239 0xe2, 0x8b, 0xc0, 0xb6, 0xfb, 0x37, 0x8c, 0x8e,
240 0xf1, 0x46, 0xbe, 0x00
241 };
242 /* clang-format on */
243
244 static const srtp_auth_test_case_t srtp_hmac_test_case_0 = {
245 sizeof(srtp_hmac_test_case_0_key), /* octets in key */
246 srtp_hmac_test_case_0_key, /* key */
247 sizeof(srtp_hmac_test_case_0_data), /* octets in data */
248 srtp_hmac_test_case_0_data, /* data */
249 sizeof(srtp_hmac_test_case_0_tag), /* octets in tag */
250 srtp_hmac_test_case_0_tag, /* tag */
251 NULL /* pointer to next testcase */
252 };
253
254 /* end test case 0 */
255
256 static const char srtp_hmac_description[] =
257 "hmac sha-1 authentication function";
258
259 /*
260 * srtp_auth_type_t hmac is the hmac metaobject
261 */
262
263 const srtp_auth_type_t srtp_hmac = {
264 srtp_hmac_alloc, /* */
265 srtp_hmac_dealloc, /* */
266 srtp_hmac_init, /* */
267 srtp_hmac_compute, /* */
268 srtp_hmac_update, /* */
269 srtp_hmac_start, /* */
270 srtp_hmac_description, /* */
271 &srtp_hmac_test_case_0, /* */
272 SRTP_HMAC_SHA1 /* */
273 };
274