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