blob: be4065908a31d09064a8c8b2667083fa9f62b509 [file] [log] [blame]
/*
* hmac.c
*
* implementation of hmac srtp_auth_type_t
*
* David A. McGrew
* Cisco Systems, Inc.
*/
/*
*
* Copyright(c) 2001-2006 Cisco Systems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* Neither the name of the Cisco Systems, Inc. nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "hmac.h"
#include "alloc.h"
/* the debug module for authentiation */
srtp_debug_module_t srtp_mod_hmac = {
0, /* debugging is off by default */
"hmac sha-1" /* printable name for module */
};
static srtp_err_status_t srtp_hmac_alloc (srtp_auth_t **a, int key_len, int out_len)
{
extern srtp_auth_type_t srtp_hmac;
uint8_t *pointer;
debug_print(srtp_mod_hmac, "allocating auth func with key length %d", key_len);
debug_print(srtp_mod_hmac, " tag length %d", out_len);
/*
* check key length - note that we don't support keys larger
* than 20 bytes yet
*/
if (key_len > 20) {
return srtp_err_status_bad_param;
}
/* check output length - should be less than 20 bytes */
if (out_len > 20) {
return srtp_err_status_bad_param;
}
/* allocate memory for auth and srtp_hmac_ctx_t structures */
pointer = (uint8_t*)srtp_crypto_alloc(sizeof(srtp_hmac_ctx_t) + sizeof(srtp_auth_t));
if (pointer == NULL) {
return srtp_err_status_alloc_fail;
}
/* set pointers */
*a = (srtp_auth_t*)pointer;
(*a)->type = &srtp_hmac;
(*a)->state = pointer + sizeof(srtp_auth_t);
(*a)->out_len = out_len;
(*a)->key_len = key_len;
(*a)->prefix_len = 0;
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_hmac_dealloc (srtp_auth_t *a)
{
/* zeroize entire state*/
octet_string_set_to_zero((uint8_t*)a,
sizeof(srtp_hmac_ctx_t) + sizeof(srtp_auth_t));
/* free memory */
srtp_crypto_free(a);
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_hmac_init (srtp_hmac_ctx_t *state, const uint8_t *key, int key_len)
{
int i;
uint8_t ipad[64];
/*
* check key length - note that we don't support keys larger
* than 20 bytes yet
*/
if (key_len > 20) {
return srtp_err_status_bad_param;
}
/*
* set values of ipad and opad by exoring the key into the
* appropriate constant values
*/
for (i = 0; i < key_len; i++) {
ipad[i] = key[i] ^ 0x36;
state->opad[i] = key[i] ^ 0x5c;
}
/* set the rest of ipad, opad to constant values */
for (; i < 64; i++) {
ipad[i] = 0x36;
((uint8_t*)state->opad)[i] = 0x5c;
}
debug_print(srtp_mod_hmac, "ipad: %s", srtp_octet_string_hex_string(ipad, 64));
/* initialize sha1 context */
srtp_sha1_init(&state->init_ctx);
/* hash ipad ^ key */
srtp_sha1_update(&state->init_ctx, ipad, 64);
memcpy(&state->ctx, &state->init_ctx, sizeof(srtp_sha1_ctx_t));
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_hmac_start (srtp_hmac_ctx_t *state)
{
memcpy(&state->ctx, &state->init_ctx, sizeof(srtp_sha1_ctx_t));
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_hmac_update (srtp_hmac_ctx_t *state, const uint8_t *message, int msg_octets)
{
debug_print(srtp_mod_hmac, "input: %s",
srtp_octet_string_hex_string(message, msg_octets));
/* hash message into sha1 context */
srtp_sha1_update(&state->ctx, message, msg_octets);
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_hmac_compute (srtp_hmac_ctx_t *state, const void *message,
int msg_octets, int tag_len, uint8_t *result)
{
uint32_t hash_value[5];
uint32_t H[5];
int i;
/* check tag length, return error if we can't provide the value expected */
if (tag_len > 20) {
return srtp_err_status_bad_param;
}
/* hash message, copy output into H */
srtp_hmac_update(state, (const uint8_t*)message, msg_octets);
srtp_sha1_final(&state->ctx, H);
/*
* note that we don't need to debug_print() the input, since the
* function hmac_update() already did that for us
*/
debug_print(srtp_mod_hmac, "intermediate state: %s",
srtp_octet_string_hex_string((uint8_t*)H, 20));
/* re-initialize hash context */
srtp_sha1_init(&state->ctx);
/* hash opad ^ key */
srtp_sha1_update(&state->ctx, (uint8_t*)state->opad, 64);
/* hash the result of the inner hash */
srtp_sha1_update(&state->ctx, (uint8_t*)H, 20);
/* the result is returned in the array hash_value[] */
srtp_sha1_final(&state->ctx, hash_value);
/* copy hash_value to *result */
for (i = 0; i < tag_len; i++) {
result[i] = ((uint8_t*)hash_value)[i];
}
debug_print(srtp_mod_hmac, "output: %s",
srtp_octet_string_hex_string((uint8_t*)hash_value, tag_len));
return srtp_err_status_ok;
}
/* begin test case 0 */
static uint8_t srtp_hmac_test_case_0_key[20] = {
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
0x0b, 0x0b, 0x0b, 0x0b
};
static uint8_t srtp_hmac_test_case_0_data[8] = {
0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65 /* "Hi There" */
};
static uint8_t srtp_hmac_test_case_0_tag[20] = {
0xb6, 0x17, 0x31, 0x86, 0x55, 0x05, 0x72, 0x64,
0xe2, 0x8b, 0xc0, 0xb6, 0xfb, 0x37, 0x8c, 0x8e,
0xf1, 0x46, 0xbe, 0x00
};
static srtp_auth_test_case_t srtp_hmac_test_case_0 = {
20, /* octets in key */
srtp_hmac_test_case_0_key, /* key */
8, /* octets in data */
srtp_hmac_test_case_0_data, /* data */
20, /* octets in tag */
srtp_hmac_test_case_0_tag, /* tag */
NULL /* pointer to next testcase */
};
/* end test case 0 */
static char srtp_hmac_description[] = "hmac sha-1 authentication function";
/*
* srtp_auth_type_t hmac is the hmac metaobject
*/
srtp_auth_type_t srtp_hmac = {
(auth_alloc_func)srtp_hmac_alloc,
(auth_dealloc_func)srtp_hmac_dealloc,
(auth_init_func)srtp_hmac_init,
(auth_compute_func)srtp_hmac_compute,
(auth_update_func)srtp_hmac_update,
(auth_start_func)srtp_hmac_start,
(char*)srtp_hmac_description,
(srtp_auth_test_case_t*)&srtp_hmac_test_case_0,
(srtp_debug_module_t*)&srtp_mod_hmac,
(srtp_auth_type_id_t)SRTP_HMAC_SHA1
};