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			283 lines
		
	
	
	
		
			8.5 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			283 lines
		
	
	
	
		
			8.5 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
| /*
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|  * hmac.c
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|  *
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|  * implementation of hmac srtp_auth_type_t
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|  *
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|  * David A. McGrew
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|  * Cisco Systems, Inc.
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|  */
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| /*
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|  *
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|  * Copyright(c) 2001-2017 Cisco Systems, Inc.
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|  * All rights reserved.
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|  *
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|  * Redistribution and use in source and binary forms, with or without
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|  * modification, are permitted provided that the following conditions
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|  * are met:
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|  *
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|  *   Redistributions of source code must retain the above copyright
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|  *   notice, this list of conditions and the following disclaimer.
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|  *
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|  *   Redistributions in binary form must reproduce the above
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|  *   copyright notice, this list of conditions and the following
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|  *   disclaimer in the documentation and/or other materials provided
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|  *   with the distribution.
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|  *
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|  *   Neither the name of the Cisco Systems, Inc. nor the names of its
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|  *   contributors may be used to endorse or promote products derived
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|  *   from this software without specific prior written permission.
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|  *
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|  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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|  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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|  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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|  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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|  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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|  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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|  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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|  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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|  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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|  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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|  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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|  * OF THE POSSIBILITY OF SUCH DAMAGE.
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|  *
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|  */
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| 
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| #ifdef HAVE_CONFIG_H
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| #include <config.h>
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| #endif
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| 
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| #include "hmac.h"
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| #include "alloc.h"
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| #include "cipher_types.h"
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| 
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| /* the debug module for authentiation */
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| 
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| srtp_debug_module_t srtp_mod_hmac = {
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|     0,           /* debugging is off by default */
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|     "hmac sha-1" /* printable name for module   */
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| };
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| 
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| static srtp_err_status_t srtp_hmac_alloc(srtp_auth_t **a,
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|                                          int key_len,
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|                                          int out_len)
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| {
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|     extern const srtp_auth_type_t srtp_hmac;
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|     uint8_t *pointer;
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| 
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|     debug_print(srtp_mod_hmac, "allocating auth func with key length %d",
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|                 key_len);
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|     debug_print(srtp_mod_hmac, "                          tag length %d",
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|                 out_len);
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| 
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|     /*
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|      * check key length - note that we don't support keys larger
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|      * than 20 bytes yet
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|      */
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|     if (key_len > 20) {
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|         return srtp_err_status_bad_param;
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|     }
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| 
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|     /* check output length - should be less than 20 bytes */
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|     if (out_len > 20) {
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|         return srtp_err_status_bad_param;
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|     }
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| 
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|     /* allocate memory for auth and srtp_hmac_ctx_t structures */
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|     pointer = (uint8_t *)srtp_crypto_alloc(sizeof(srtp_hmac_ctx_t) +
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|                                            sizeof(srtp_auth_t));
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|     if (pointer == NULL) {
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|         return srtp_err_status_alloc_fail;
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|     }
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| 
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|     /* set pointers */
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|     *a = (srtp_auth_t *)pointer;
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|     (*a)->type = &srtp_hmac;
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|     (*a)->state = pointer + sizeof(srtp_auth_t);
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|     (*a)->out_len = out_len;
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|     (*a)->key_len = key_len;
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|     (*a)->prefix_len = 0;
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| 
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|     return srtp_err_status_ok;
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| }
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| 
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| static srtp_err_status_t srtp_hmac_dealloc(srtp_auth_t *a)
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| {
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|     /* zeroize entire state*/
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|     octet_string_set_to_zero(a, sizeof(srtp_hmac_ctx_t) + sizeof(srtp_auth_t));
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| 
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|     /* free memory */
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|     srtp_crypto_free(a);
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| 
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|     return srtp_err_status_ok;
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| }
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| 
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| static srtp_err_status_t srtp_hmac_init(void *statev,
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|                                         const uint8_t *key,
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|                                         int key_len)
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| {
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|     srtp_hmac_ctx_t *state = (srtp_hmac_ctx_t *)statev;
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|     int i;
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|     uint8_t ipad[64];
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| 
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|     /*
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|      * check key length - note that we don't support keys larger
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|      * than 20 bytes yet
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|      */
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|     if (key_len > 20) {
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|         return srtp_err_status_bad_param;
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|     }
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| 
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|     /*
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|      * set values of ipad and opad by exoring the key into the
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|      * appropriate constant values
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|      */
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|     for (i = 0; i < key_len; i++) {
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|         ipad[i] = key[i] ^ 0x36;
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|         state->opad[i] = key[i] ^ 0x5c;
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|     }
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|     /* set the rest of ipad, opad to constant values */
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|     for (; i < 64; i++) {
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|         ipad[i] = 0x36;
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|         ((uint8_t *)state->opad)[i] = 0x5c;
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|     }
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| 
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|     debug_print(srtp_mod_hmac, "ipad: %s",
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|                 srtp_octet_string_hex_string(ipad, 64));
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| 
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|     /* initialize sha1 context */
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|     srtp_sha1_init(&state->init_ctx);
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| 
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|     /* hash ipad ^ key */
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|     srtp_sha1_update(&state->init_ctx, ipad, 64);
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|     memcpy(&state->ctx, &state->init_ctx, sizeof(srtp_sha1_ctx_t));
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| 
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|     return srtp_err_status_ok;
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| }
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| 
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| static srtp_err_status_t srtp_hmac_start(void *statev)
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| {
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|     srtp_hmac_ctx_t *state = (srtp_hmac_ctx_t *)statev;
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| 
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|     memcpy(&state->ctx, &state->init_ctx, sizeof(srtp_sha1_ctx_t));
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| 
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|     return srtp_err_status_ok;
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| }
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| 
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| static srtp_err_status_t srtp_hmac_update(void *statev,
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|                                           const uint8_t *message,
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|                                           int msg_octets)
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| {
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|     srtp_hmac_ctx_t *state = (srtp_hmac_ctx_t *)statev;
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| 
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|     debug_print(srtp_mod_hmac, "input: %s",
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|                 srtp_octet_string_hex_string(message, msg_octets));
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| 
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|     /* hash message into sha1 context */
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|     srtp_sha1_update(&state->ctx, message, msg_octets);
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| 
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|     return srtp_err_status_ok;
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| }
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| 
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| static srtp_err_status_t srtp_hmac_compute(void *statev,
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|                                            const uint8_t *message,
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|                                            int msg_octets,
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|                                            int tag_len,
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|                                            uint8_t *result)
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| {
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|     srtp_hmac_ctx_t *state = (srtp_hmac_ctx_t *)statev;
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|     uint32_t hash_value[5];
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|     uint32_t H[5];
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|     int i;
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| 
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|     /* check tag length, return error if we can't provide the value expected */
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|     if (tag_len > 20) {
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|         return srtp_err_status_bad_param;
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|     }
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| 
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|     /* hash message, copy output into H */
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|     srtp_hmac_update(state, message, msg_octets);
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|     srtp_sha1_final(&state->ctx, H);
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| 
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|     /*
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|      * note that we don't need to debug_print() the input, since the
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|      * function hmac_update() already did that for us
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|      */
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|     debug_print(srtp_mod_hmac, "intermediate state: %s",
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|                 srtp_octet_string_hex_string((uint8_t *)H, 20));
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| 
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|     /* re-initialize hash context */
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|     srtp_sha1_init(&state->ctx);
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| 
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|     /* hash opad ^ key  */
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|     srtp_sha1_update(&state->ctx, (uint8_t *)state->opad, 64);
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| 
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|     /* hash the result of the inner hash */
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|     srtp_sha1_update(&state->ctx, (uint8_t *)H, 20);
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| 
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|     /* the result is returned in the array hash_value[] */
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|     srtp_sha1_final(&state->ctx, hash_value);
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| 
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|     /* copy hash_value to *result */
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|     for (i = 0; i < tag_len; i++) {
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|         result[i] = ((uint8_t *)hash_value)[i];
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|     }
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| 
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|     debug_print(srtp_mod_hmac, "output: %s",
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|                 srtp_octet_string_hex_string((uint8_t *)hash_value, tag_len));
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| 
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|     return srtp_err_status_ok;
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| }
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| 
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| /* begin test case 0 */
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| /* clang-format off */
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| static const uint8_t srtp_hmac_test_case_0_key[20] = {
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|     0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
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|     0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
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|     0x0b, 0x0b, 0x0b, 0x0b
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| };
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| /* clang-format on */
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| 
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| /* clang-format off */
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| static const uint8_t srtp_hmac_test_case_0_data[8] = {
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|     0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65 /* "Hi There" */
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| };
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| /* clang-format on */
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| 
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| /* clang-format off */
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| static const uint8_t srtp_hmac_test_case_0_tag[20] = {
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|     0xb6, 0x17, 0x31, 0x86, 0x55, 0x05, 0x72, 0x64,
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|     0xe2, 0x8b, 0xc0, 0xb6, 0xfb, 0x37, 0x8c, 0x8e,
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|     0xf1, 0x46, 0xbe, 0x00
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| };
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| /* clang-format on */
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| 
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| static const srtp_auth_test_case_t srtp_hmac_test_case_0 = {
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|     20,                         /* octets in key            */
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|     srtp_hmac_test_case_0_key,  /* key                      */
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|     8,                          /* octets in data           */
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|     srtp_hmac_test_case_0_data, /* data                     */
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|     20,                         /* octets in tag            */
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|     srtp_hmac_test_case_0_tag,  /* tag                      */
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|     NULL                        /* pointer to next testcase */
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| };
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| 
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| /* end test case 0 */
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| 
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| static const char srtp_hmac_description[] =
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|     "hmac sha-1 authentication function";
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| 
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| /*
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|  * srtp_auth_type_t hmac is the hmac metaobject
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|  */
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| 
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| const srtp_auth_type_t srtp_hmac = {
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|     srtp_hmac_alloc,        /* */
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|     srtp_hmac_dealloc,      /* */
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|     srtp_hmac_init,         /* */
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|     srtp_hmac_compute,      /* */
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|     srtp_hmac_update,       /* */
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|     srtp_hmac_start,        /* */
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|     srtp_hmac_description,  /* */
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|     &srtp_hmac_test_case_0, /* */
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|     SRTP_HMAC_SHA1          /* */
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| };
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