521 lines
17 KiB
C
521 lines
17 KiB
C
/*
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* aes_icm.c
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*
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* AES Integer Counter Mode
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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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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#define ALIGN_32 0
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#include "aes_icm.h"
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#include "alloc.h"
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srtp_debug_module_t srtp_mod_aes_icm = {
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0, /* debugging is off by default */
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"aes icm" /* printable module name */
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};
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extern const srtp_cipher_type_t srtp_aes_icm_128;
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extern const srtp_cipher_type_t srtp_aes_icm_256;
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/*
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* integer counter mode works as follows:
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*
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* 16 bits
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* <----->
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* +------+------+------+------+------+------+------+------+
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* | nonce | pakcet index | ctr |---+
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* +------+------+------+------+------+------+------+------+ |
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* |
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* +------+------+------+------+------+------+------+------+ v
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* | salt |000000|->(+)
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* +------+------+------+------+------+------+------+------+ |
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* |
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* +---------+
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* | encrypt |
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* +---------+
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* |
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* +------+------+------+------+------+------+------+------+ |
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* | keystream block |<--+
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* +------+------+------+------+------+------+------+------+
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*
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* All fields are big-endian
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*
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* ctr is the block counter, which increments from zero for
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* each packet (16 bits wide)
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*
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* packet index is distinct for each packet (48 bits wide)
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*
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* nonce can be distinct across many uses of the same key, or
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* can be a fixed value per key, or can be per-packet randomness
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* (64 bits)
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*
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*/
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static srtp_err_status_t srtp_aes_icm_alloc (srtp_cipher_t **c, int key_len, int tlen)
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{
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srtp_aes_icm_ctx_t *icm;
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debug_print(srtp_mod_aes_icm,
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"allocating cipher with key length %d", key_len);
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/*
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* The check for key_len = 30/46 does not apply. Our usage
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* of aes functions with key_len = values other than 30
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* has not broken anything. Don't know what would be the
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* effect of skipping this check for srtp in general.
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*/
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if (key_len != SRTP_AES_ICM_128_KEY_LEN_WSALT && key_len != SRTP_AES_ICM_256_KEY_LEN_WSALT) {
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return srtp_err_status_bad_param;
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}
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/* allocate memory a cipher of type aes_icm */
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*c = (srtp_cipher_t *)srtp_crypto_alloc(sizeof(srtp_cipher_t));
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if (*c == NULL) {
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return srtp_err_status_alloc_fail;
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}
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memset(*c, 0x0, sizeof(srtp_cipher_t));
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icm = (srtp_aes_icm_ctx_t *)srtp_crypto_alloc(sizeof(srtp_aes_icm_ctx_t));
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if (icm == NULL) {
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srtp_crypto_free(*c);
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return srtp_err_status_alloc_fail;
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}
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memset(icm, 0x0, sizeof(srtp_aes_icm_ctx_t));
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/* set pointers */
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(*c)->state = icm;
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switch (key_len) {
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case SRTP_AES_ICM_256_KEY_LEN_WSALT:
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(*c)->algorithm = SRTP_AES_ICM_256;
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(*c)->type = &srtp_aes_icm_256;
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break;
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default:
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(*c)->algorithm = SRTP_AES_ICM_128;
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(*c)->type = &srtp_aes_icm_128;
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break;
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}
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/* set key size */
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icm->key_size = key_len;
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(*c)->key_len = key_len;
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return srtp_err_status_ok;
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}
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static srtp_err_status_t srtp_aes_icm_dealloc (srtp_cipher_t *c)
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{
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srtp_aes_icm_ctx_t *ctx;
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if (c == NULL) {
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return srtp_err_status_bad_param;
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}
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ctx = (srtp_aes_icm_ctx_t *)c->state;
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if (ctx) {
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/* zeroize the key material */
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octet_string_set_to_zero(ctx, sizeof(srtp_aes_icm_ctx_t));
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srtp_crypto_free(ctx);
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}
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/* free the cipher context */
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srtp_crypto_free(c);
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return srtp_err_status_ok;
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}
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/*
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* aes_icm_context_init(...) initializes the aes_icm_context
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* using the value in key[].
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*
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* the key is the secret key
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*
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* the salt is unpredictable (but not necessarily secret) data which
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* randomizes the starting point in the keystream
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*/
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static srtp_err_status_t srtp_aes_icm_context_init (void *cv, const uint8_t *key)
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{
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srtp_aes_icm_ctx_t *c = (srtp_aes_icm_ctx_t *)cv;
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srtp_err_status_t status;
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int base_key_len, copy_len;
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if (c->key_size == SRTP_AES_ICM_128_KEY_LEN_WSALT || c->key_size == SRTP_AES_ICM_256_KEY_LEN_WSALT) {
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base_key_len = c->key_size - SRTP_SALT_LEN;
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} else{
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return srtp_err_status_bad_param;
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}
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/*
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* set counter and initial values to 'offset' value, being careful not to
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* go past the end of the key buffer
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*/
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v128_set_to_zero(&c->counter);
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v128_set_to_zero(&c->offset);
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copy_len = c->key_size - base_key_len;
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/* force last two octets of the offset to be left zero (for srtp compatibility) */
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if (copy_len > SRTP_SALT_LEN) {
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copy_len = SRTP_SALT_LEN;
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}
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memcpy(&c->counter, key + base_key_len, copy_len);
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memcpy(&c->offset, key + base_key_len, copy_len);
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debug_print(srtp_mod_aes_icm,
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"key: %s", srtp_octet_string_hex_string(key, base_key_len));
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debug_print(srtp_mod_aes_icm,
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"offset: %s", v128_hex_string(&c->offset));
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/* expand key */
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status = srtp_aes_expand_encryption_key(key, base_key_len, &c->expanded_key);
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if (status) {
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v128_set_to_zero(&c->counter);
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v128_set_to_zero(&c->offset);
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return status;
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}
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/* indicate that the keystream_buffer is empty */
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c->bytes_in_buffer = 0;
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return srtp_err_status_ok;
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}
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/*
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* aes_icm_set_iv(c, iv) sets the counter value to the exor of iv with
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* the offset
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*/
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static srtp_err_status_t srtp_aes_icm_set_iv (void *cv, uint8_t *iv, srtp_cipher_direction_t direction)
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{
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srtp_aes_icm_ctx_t *c = (srtp_aes_icm_ctx_t *)cv;
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v128_t nonce;
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/* set nonce (for alignment) */
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v128_copy_octet_string(&nonce, iv);
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debug_print(srtp_mod_aes_icm,
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"setting iv: %s", v128_hex_string(&nonce));
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v128_xor(&c->counter, &c->offset, &nonce);
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debug_print(srtp_mod_aes_icm,
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"set_counter: %s", v128_hex_string(&c->counter));
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/* indicate that the keystream_buffer is empty */
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c->bytes_in_buffer = 0;
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return srtp_err_status_ok;
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}
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/*
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* aes_icm_advance(...) refills the keystream_buffer and
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* advances the block index of the sicm_context forward by one
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*
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* this is an internal, hopefully inlined function
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*/
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static void srtp_aes_icm_advance (srtp_aes_icm_ctx_t *c)
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{
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/* fill buffer with new keystream */
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v128_copy(&c->keystream_buffer, &c->counter);
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srtp_aes_encrypt(&c->keystream_buffer, &c->expanded_key);
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c->bytes_in_buffer = sizeof(v128_t);
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debug_print(srtp_mod_aes_icm, "counter: %s",
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v128_hex_string(&c->counter));
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debug_print(srtp_mod_aes_icm, "ciphertext: %s",
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v128_hex_string(&c->keystream_buffer));
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/* clock counter forward */
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if (!++(c->counter.v8[15])) {
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++(c->counter.v8[14]);
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}
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}
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/*e
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* icm_encrypt deals with the following cases:
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*
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* bytes_to_encr < bytes_in_buffer
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* - add keystream into data
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*
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* bytes_to_encr > bytes_in_buffer
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* - add keystream into data until keystream_buffer is depleted
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* - loop over blocks, filling keystream_buffer and then
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* adding keystream into data
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* - fill buffer then add in remaining (< 16) bytes of keystream
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*/
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static srtp_err_status_t srtp_aes_icm_encrypt (void *cv,
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unsigned char *buf, unsigned int *enc_len)
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{
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srtp_aes_icm_ctx_t *c = (srtp_aes_icm_ctx_t*)cv;
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unsigned int bytes_to_encr = *enc_len;
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unsigned int i;
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uint32_t *b;
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/* check that there's enough segment left*/
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if ((bytes_to_encr + htons(c->counter.v16[7])) > 0xffff) {
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return srtp_err_status_terminus;
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}
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debug_print(srtp_mod_aes_icm, "block index: %d",
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htons(c->counter.v16[7]));
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if (bytes_to_encr <= (unsigned int)c->bytes_in_buffer) {
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/* deal with odd case of small bytes_to_encr */
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for (i = (sizeof(v128_t) - c->bytes_in_buffer);
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i < (sizeof(v128_t) - c->bytes_in_buffer + bytes_to_encr); i++) {
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*buf++ ^= c->keystream_buffer.v8[i];
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}
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c->bytes_in_buffer -= bytes_to_encr;
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/* return now to avoid the main loop */
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return srtp_err_status_ok;
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} else {
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/* encrypt bytes until the remaining data is 16-byte aligned */
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for (i = (sizeof(v128_t) - c->bytes_in_buffer); i < sizeof(v128_t); i++) {
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*buf++ ^= c->keystream_buffer.v8[i];
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}
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bytes_to_encr -= c->bytes_in_buffer;
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c->bytes_in_buffer = 0;
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}
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/* now loop over entire 16-byte blocks of keystream */
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for (i = 0; i < (bytes_to_encr / sizeof(v128_t)); i++) {
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/* fill buffer with new keystream */
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srtp_aes_icm_advance(c);
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/*
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* add keystream into the data buffer (this would be a lot faster
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* if we could assume 32-bit alignment!)
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*/
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#if ALIGN_32
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b = (uint32_t*)buf;
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*b++ ^= c->keystream_buffer.v32[0];
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*b++ ^= c->keystream_buffer.v32[1];
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*b++ ^= c->keystream_buffer.v32[2];
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*b++ ^= c->keystream_buffer.v32[3];
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buf = (uint8_t*)b;
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#else
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if ((((unsigned long)buf) & 0x03) != 0) {
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*buf++ ^= c->keystream_buffer.v8[0];
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*buf++ ^= c->keystream_buffer.v8[1];
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*buf++ ^= c->keystream_buffer.v8[2];
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*buf++ ^= c->keystream_buffer.v8[3];
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*buf++ ^= c->keystream_buffer.v8[4];
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*buf++ ^= c->keystream_buffer.v8[5];
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*buf++ ^= c->keystream_buffer.v8[6];
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*buf++ ^= c->keystream_buffer.v8[7];
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*buf++ ^= c->keystream_buffer.v8[8];
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*buf++ ^= c->keystream_buffer.v8[9];
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*buf++ ^= c->keystream_buffer.v8[10];
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*buf++ ^= c->keystream_buffer.v8[11];
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*buf++ ^= c->keystream_buffer.v8[12];
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*buf++ ^= c->keystream_buffer.v8[13];
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*buf++ ^= c->keystream_buffer.v8[14];
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*buf++ ^= c->keystream_buffer.v8[15];
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} else {
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b = (uint32_t*)buf;
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*b++ ^= c->keystream_buffer.v32[0];
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*b++ ^= c->keystream_buffer.v32[1];
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*b++ ^= c->keystream_buffer.v32[2];
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*b++ ^= c->keystream_buffer.v32[3];
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buf = (uint8_t*)b;
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}
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#endif /* #if ALIGN_32 */
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}
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/* if there is a tail end of the data, process it */
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if ((bytes_to_encr & 0xf) != 0) {
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/* fill buffer with new keystream */
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srtp_aes_icm_advance(c);
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for (i = 0; i < (bytes_to_encr & 0xf); i++) {
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*buf++ ^= c->keystream_buffer.v8[i];
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}
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/* reset the keystream buffer size to right value */
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c->bytes_in_buffer = sizeof(v128_t) - i;
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} else {
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/* no tail, so just reset the keystream buffer size to zero */
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c->bytes_in_buffer = 0;
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}
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return srtp_err_status_ok;
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}
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static const char srtp_aes_icm_128_description[] = "AES-128 integer counter mode";
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static const char srtp_aes_icm_256_description[] = "AES-256 integer counter mode";
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static const uint8_t srtp_aes_icm_128_test_case_0_key[SRTP_AES_ICM_128_KEY_LEN_WSALT] = {
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0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6,
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0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c,
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0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
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0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd
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};
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static uint8_t srtp_aes_icm_128_test_case_0_nonce[16] = {
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
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};
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static const uint8_t srtp_aes_icm_128_test_case_0_plaintext[32] = {
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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};
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static const uint8_t srtp_aes_icm_128_test_case_0_ciphertext[32] = {
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0xe0, 0x3e, 0xad, 0x09, 0x35, 0xc9, 0x5e, 0x80,
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0xe1, 0x66, 0xb1, 0x6d, 0xd9, 0x2b, 0x4e, 0xb4,
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0xd2, 0x35, 0x13, 0x16, 0x2b, 0x02, 0xd0, 0xf7,
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0x2a, 0x43, 0xa2, 0xfe, 0x4a, 0x5f, 0x97, 0xab
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};
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static const srtp_cipher_test_case_t srtp_aes_icm_128_test_case_0 = {
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SRTP_AES_ICM_128_KEY_LEN_WSALT, /* octets in key */
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srtp_aes_icm_128_test_case_0_key, /* key */
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srtp_aes_icm_128_test_case_0_nonce, /* packet index */
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32, /* octets in plaintext */
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srtp_aes_icm_128_test_case_0_plaintext, /* plaintext */
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32, /* octets in ciphertext */
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srtp_aes_icm_128_test_case_0_ciphertext, /* ciphertext */
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0,
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NULL,
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0,
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NULL /* pointer to next testcase */
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};
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static const uint8_t srtp_aes_icm_256_test_case_0_key[SRTP_AES_ICM_256_KEY_LEN_WSALT] = {
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0x57, 0xf8, 0x2f, 0xe3, 0x61, 0x3f, 0xd1, 0x70,
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0xa8, 0x5e, 0xc9, 0x3c, 0x40, 0xb1, 0xf0, 0x92,
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0x2e, 0xc4, 0xcb, 0x0d, 0xc0, 0x25, 0xb5, 0x82,
|
|
0x72, 0x14, 0x7c, 0xc4, 0x38, 0x94, 0x4a, 0x98,
|
|
0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
|
|
0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd
|
|
};
|
|
|
|
static uint8_t srtp_aes_icm_256_test_case_0_nonce[16] = {
|
|
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
|
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
|
|
};
|
|
|
|
static const uint8_t srtp_aes_icm_256_test_case_0_plaintext[32] = {
|
|
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
|
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
|
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
|
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
|
};
|
|
|
|
static const uint8_t srtp_aes_icm_256_test_case_0_ciphertext[32] = {
|
|
0x92, 0xbd, 0xd2, 0x8a, 0x93, 0xc3, 0xf5, 0x25,
|
|
0x11, 0xc6, 0x77, 0xd0, 0x8b, 0x55, 0x15, 0xa4,
|
|
0x9d, 0xa7, 0x1b, 0x23, 0x78, 0xa8, 0x54, 0xf6,
|
|
0x70, 0x50, 0x75, 0x6d, 0xed, 0x16, 0x5b, 0xac
|
|
};
|
|
|
|
static const srtp_cipher_test_case_t srtp_aes_icm_256_test_case_0 = {
|
|
SRTP_AES_ICM_256_KEY_LEN_WSALT, /* octets in key */
|
|
srtp_aes_icm_256_test_case_0_key, /* key */
|
|
srtp_aes_icm_256_test_case_0_nonce, /* packet index */
|
|
32, /* octets in plaintext */
|
|
srtp_aes_icm_256_test_case_0_plaintext, /* plaintext */
|
|
32, /* octets in ciphertext */
|
|
srtp_aes_icm_256_test_case_0_ciphertext, /* ciphertext */
|
|
0,
|
|
NULL,
|
|
0,
|
|
NULL, /* pointer to next testcase */
|
|
};
|
|
|
|
|
|
|
|
/*
|
|
* note: the encrypt function is identical to the decrypt function
|
|
*/
|
|
|
|
const srtp_cipher_type_t srtp_aes_icm_128 = {
|
|
srtp_aes_icm_alloc,
|
|
srtp_aes_icm_dealloc,
|
|
srtp_aes_icm_context_init,
|
|
0, /* set_aad */
|
|
srtp_aes_icm_encrypt,
|
|
srtp_aes_icm_encrypt,
|
|
srtp_aes_icm_set_iv,
|
|
0, /* get_tag */
|
|
srtp_aes_icm_128_description,
|
|
&srtp_aes_icm_128_test_case_0,
|
|
SRTP_AES_ICM_128
|
|
};
|
|
|
|
const srtp_cipher_type_t srtp_aes_icm_256 = {
|
|
srtp_aes_icm_alloc,
|
|
srtp_aes_icm_dealloc,
|
|
srtp_aes_icm_context_init,
|
|
0, /* set_aad */
|
|
srtp_aes_icm_encrypt,
|
|
srtp_aes_icm_encrypt,
|
|
srtp_aes_icm_set_iv,
|
|
0, /* get_tag */
|
|
srtp_aes_icm_256_description,
|
|
&srtp_aes_icm_256_test_case_0,
|
|
SRTP_AES_ICM_256
|
|
};
|