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/*
* hmac_mbedtls.c
*
* Implementation of hmac srtp_auth_type_t that leverages Mbedtls
*
* YongCheng Yang
*/
/*
*
* Copyright(c) 2013-2017, 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 "auth.h"
#include "alloc.h"
#include "err.h" /* for srtp_debug */
#include "auth_test_cases.h"
#include <mbedtls/md.h>
#define SHA1_DIGEST_SIZE 20
/* the debug module for authentiation */
srtp_debug_module_t srtp_mod_hmac = {
0, /* debugging is off by default */
"hmac sha-1 mbedtls" /* printable name for module */
};
static srtp_err_status_t srtp_hmac_mbedtls_alloc(srtp_auth_t **a,
int key_len,
int out_len)
{
extern const srtp_auth_type_t srtp_hmac;
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 output length - should be less than 20 bytes */
if (key_len > SHA1_DIGEST_SIZE) {
return srtp_err_status_bad_param;
}
/* check output length - should be less than 20 bytes */
if (out_len > SHA1_DIGEST_SIZE) {
return srtp_err_status_bad_param;
}
*a = (srtp_auth_t *)srtp_crypto_alloc(sizeof(srtp_auth_t));
if (*a == NULL) {
return srtp_err_status_alloc_fail;
}
// allocate the buffer of mbedtls context.
(*a)->state = srtp_crypto_alloc(sizeof(mbedtls_md_context_t));
if ((*a)->state == NULL) {
srtp_crypto_free(*a);
*a = NULL;
return srtp_err_status_alloc_fail;
}
mbedtls_md_init((mbedtls_md_context_t *)(*a)->state);
/* set pointers */
(*a)->type = &srtp_hmac;
(*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_mbedtls_dealloc(srtp_auth_t *a)
{
mbedtls_md_context_t *hmac_ctx;
hmac_ctx = (mbedtls_md_context_t *)a->state;
mbedtls_md_free(hmac_ctx);
srtp_crypto_free(hmac_ctx);
/* zeroize entire state*/
octet_string_set_to_zero(a, sizeof(srtp_auth_t));
/* free memory */
srtp_crypto_free(a);
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_hmac_mbedtls_start(void *statev)
{
mbedtls_md_context_t *state = (mbedtls_md_context_t *)statev;
if (mbedtls_md_hmac_reset(state) != 0)
return srtp_err_status_auth_fail;
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_hmac_mbedtls_init(void *statev,
const uint8_t *key,
int key_len)
{
mbedtls_md_context_t *state = (mbedtls_md_context_t *)statev;
const mbedtls_md_info_t *info = NULL;
info = mbedtls_md_info_from_type(MBEDTLS_MD_SHA1);
if (info == NULL)
return srtp_err_status_auth_fail;
if (mbedtls_md_setup(state, info, 1) != 0)
return srtp_err_status_auth_fail;
debug_print(srtp_mod_hmac, "mbedtls setup, name: %s",
mbedtls_md_get_name(info));
debug_print(srtp_mod_hmac, "mbedtls setup, size: %d",
mbedtls_md_get_size(info));
if (mbedtls_md_hmac_starts(state, key, key_len) != 0)
return srtp_err_status_auth_fail;
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_hmac_mbedtls_update(void *statev,
const uint8_t *message,
int msg_octets)
{
mbedtls_md_context_t *state = (mbedtls_md_context_t *)statev;
debug_print(srtp_mod_hmac, "input: %s",
srtp_octet_string_hex_string(message, msg_octets));
if (mbedtls_md_hmac_update(state, message, msg_octets) != 0)
return srtp_err_status_auth_fail;
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_hmac_mbedtls_compute(void *statev,
const uint8_t *message,
int msg_octets,
int tag_len,
uint8_t *result)
{
mbedtls_md_context_t *state = (mbedtls_md_context_t *)statev;
uint8_t hash_value[SHA1_DIGEST_SIZE];
int i;
/* check tag length, return error if we can't provide the value expected */
if (tag_len > SHA1_DIGEST_SIZE) {
return srtp_err_status_bad_param;
}
/* hash message, copy output into H */
if (mbedtls_md_hmac_update(statev, message, msg_octets) != 0)
return srtp_err_status_auth_fail;
if (mbedtls_md_hmac_finish(state, hash_value) != 0)
return srtp_err_status_auth_fail;
/* copy hash_value to *result */
for (i = 0; i < tag_len; i++) {
result[i] = hash_value[i];
}
debug_print(srtp_mod_hmac, "output: %s",
srtp_octet_string_hex_string(hash_value, tag_len));
return srtp_err_status_ok;
}
/* end test case 0 */
static const char srtp_hmac_mbedtls_description[] =
"hmac sha-1 authentication function using mbedtls";
/*
* srtp_auth_type_t hmac is the hmac metaobject
*/
const srtp_auth_type_t srtp_hmac = {
srtp_hmac_mbedtls_alloc, /* */
srtp_hmac_mbedtls_dealloc, /* */
srtp_hmac_mbedtls_init, /* */
srtp_hmac_mbedtls_compute, /* */
srtp_hmac_mbedtls_update, /* */
srtp_hmac_mbedtls_start, /* */
srtp_hmac_mbedtls_description, /* */
&srtp_hmac_test_case_0, /* */
SRTP_HMAC_SHA1 /* */
};
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