D-Modem/pjproject-2.11.1/third_party/srtp/crypto/cipher/null_cipher.c
2021-10-29 14:41:03 -04:00

156 lines
4.7 KiB
C

/*
* null_cipher.c
*
* A null cipher implementation. This cipher leaves the plaintext
* unchanged.
*
* David A. McGrew
* Cisco Systems, Inc.
*/
/*
*
* Copyright (c) 2001-2017 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 "datatypes.h"
#include "null_cipher.h"
#include "err.h" /* for srtp_debug */
#include "alloc.h"
/* the null_cipher uses the cipher debug module */
extern srtp_debug_module_t srtp_mod_cipher;
static srtp_err_status_t srtp_null_cipher_alloc (srtp_cipher_t **c, int key_len, int tlen)
{
extern const srtp_cipher_type_t srtp_null_cipher;
debug_print(srtp_mod_cipher,
"allocating cipher with key length %d", key_len);
/* allocate memory a cipher of type null_cipher */
*c = (srtp_cipher_t *)srtp_crypto_alloc(sizeof(srtp_cipher_t));
if (*c == NULL) {
return srtp_err_status_alloc_fail;
}
memset(*c, 0x0, sizeof(srtp_cipher_t));
/* set pointers */
(*c)->algorithm = SRTP_NULL_CIPHER;
(*c)->type = &srtp_null_cipher;
(*c)->state = (void *) 0x1; /* The null cipher does not maintain state */
/* set key size */
(*c)->key_len = key_len;
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_null_cipher_dealloc (srtp_cipher_t *c)
{
extern const srtp_cipher_type_t srtp_null_cipher;
/* zeroize entire state*/
octet_string_set_to_zero(c, sizeof(srtp_cipher_t));
/* free memory of type null_cipher */
srtp_crypto_free(c);
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_null_cipher_init (void *cv, const uint8_t *key)
{
/* srtp_null_cipher_ctx_t *c = (srtp_null_cipher_ctx_t *)cv; */
debug_print(srtp_mod_cipher, "initializing null cipher", NULL);
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_null_cipher_set_iv (void *cv, uint8_t *iv, srtp_cipher_direction_t dir)
{
/* srtp_null_cipher_ctx_t *c = (srtp_null_cipher_ctx_t *)cv; */
return srtp_err_status_ok;
}
static srtp_err_status_t srtp_null_cipher_encrypt (void *cv,
unsigned char *buf, unsigned int *bytes_to_encr)
{
/* srtp_null_cipher_ctx_t *c = (srtp_null_cipher_ctx_t *)cv; */
return srtp_err_status_ok;
}
static const char srtp_null_cipher_description[] = "null cipher";
static const srtp_cipher_test_case_t srtp_null_cipher_test_0 = {
0, /* octets in key */
NULL, /* key */
0, /* packet index */
0, /* octets in plaintext */
NULL, /* plaintext */
0, /* octets in plaintext */
NULL, /* ciphertext */
0,
NULL,
0,
NULL /* pointer to next testcase */
};
/*
* note: the decrypt function is idential to the encrypt function
*/
const srtp_cipher_type_t srtp_null_cipher = {
srtp_null_cipher_alloc,
srtp_null_cipher_dealloc,
srtp_null_cipher_init,
0, /* set_aad */
srtp_null_cipher_encrypt,
srtp_null_cipher_encrypt,
srtp_null_cipher_set_iv,
0, /* get_tag */
srtp_null_cipher_description,
&srtp_null_cipher_test_0,
SRTP_NULL_CIPHER
};