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 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 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 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 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 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 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
