156 lines
4.7 KiB
C
156 lines
4.7 KiB
C
/*
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* null_cipher.c
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*
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* A null cipher implementation. This cipher leaves the plaintext
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* unchanged.
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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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#include "datatypes.h"
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#include "null_cipher.h"
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#include "err.h" /* for srtp_debug */
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#include "alloc.h"
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/* the null_cipher uses the cipher debug module */
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extern srtp_debug_module_t srtp_mod_cipher;
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static srtp_err_status_t srtp_null_cipher_alloc (srtp_cipher_t **c, int key_len, int tlen)
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{
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extern const srtp_cipher_type_t srtp_null_cipher;
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debug_print(srtp_mod_cipher,
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"allocating cipher with key length %d", key_len);
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/* allocate memory a cipher of type null_cipher */
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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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/* set pointers */
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(*c)->algorithm = SRTP_NULL_CIPHER;
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(*c)->type = &srtp_null_cipher;
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(*c)->state = (void *) 0x1; /* The null cipher does not maintain state */
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/* set key size */
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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_null_cipher_dealloc (srtp_cipher_t *c)
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{
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extern const srtp_cipher_type_t srtp_null_cipher;
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/* zeroize entire state*/
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octet_string_set_to_zero(c, sizeof(srtp_cipher_t));
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/* free memory of type null_cipher */
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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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static srtp_err_status_t srtp_null_cipher_init (void *cv, const uint8_t *key)
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{
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/* srtp_null_cipher_ctx_t *c = (srtp_null_cipher_ctx_t *)cv; */
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debug_print(srtp_mod_cipher, "initializing null cipher", NULL);
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return srtp_err_status_ok;
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}
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static srtp_err_status_t srtp_null_cipher_set_iv (void *cv, uint8_t *iv, srtp_cipher_direction_t dir)
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{
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/* srtp_null_cipher_ctx_t *c = (srtp_null_cipher_ctx_t *)cv; */
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return srtp_err_status_ok;
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}
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static srtp_err_status_t srtp_null_cipher_encrypt (void *cv,
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unsigned char *buf, unsigned int *bytes_to_encr)
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{
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/* srtp_null_cipher_ctx_t *c = (srtp_null_cipher_ctx_t *)cv; */
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return srtp_err_status_ok;
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}
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static const char srtp_null_cipher_description[] = "null cipher";
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static const srtp_cipher_test_case_t srtp_null_cipher_test_0 = {
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0, /* octets in key */
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NULL, /* key */
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0, /* packet index */
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0, /* octets in plaintext */
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NULL, /* plaintext */
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0, /* octets in plaintext */
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NULL, /* 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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/*
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* note: the decrypt function is idential to the encrypt function
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*/
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const srtp_cipher_type_t srtp_null_cipher = {
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srtp_null_cipher_alloc,
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srtp_null_cipher_dealloc,
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srtp_null_cipher_init,
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0, /* set_aad */
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srtp_null_cipher_encrypt,
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srtp_null_cipher_encrypt,
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srtp_null_cipher_set_iv,
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0, /* get_tag */
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srtp_null_cipher_description,
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&srtp_null_cipher_test_0,
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SRTP_NULL_CIPHER
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};
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