1 /*
2 * null_cipher.c
3 *
4 * A null cipher implementation. This cipher leaves the plaintext
5 * unchanged.
6 *
7 * David A. McGrew
8 * Cisco Systems, Inc.
9 */
10
11 /*
12 *
13 * Copyright (c) 2001-2017 Cisco Systems, Inc.
14 * All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 *
20 * Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 *
23 * Redistributions in binary form must reproduce the above
24 * copyright notice, this list of conditions and the following
25 * disclaimer in the documentation and/or other materials provided
26 * with the distribution.
27 *
28 * Neither the name of the Cisco Systems, Inc. nor the names of its
29 * contributors may be used to endorse or promote products derived
30 * from this software without specific prior written permission.
31 *
32 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
33 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
34 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
35 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
36 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
37 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
38 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
39 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
40 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
41 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
42 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
43 * OF THE POSSIBILITY OF SUCH DAMAGE.
44 *
45 */
46
47 #ifdef HAVE_CONFIG_H
48 #include <config.h>
49 #endif
50
51 #include "datatypes.h"
52 #include "null_cipher.h"
53 #include "err.h" /* for srtp_debug */
54 #include "alloc.h"
55 #include "cipher_types.h"
56
srtp_null_cipher_alloc(srtp_cipher_t ** c,int key_len,int tlen)57 static srtp_err_status_t srtp_null_cipher_alloc(srtp_cipher_t **c,
58 int key_len,
59 int tlen)
60 {
61 extern const srtp_cipher_type_t srtp_null_cipher;
62
63 debug_print(srtp_mod_cipher, "allocating cipher with key length %d",
64 key_len);
65
66 /* allocate memory a cipher of type null_cipher */
67 *c = (srtp_cipher_t *)srtp_crypto_alloc(sizeof(srtp_cipher_t));
68 if (*c == NULL) {
69 return srtp_err_status_alloc_fail;
70 }
71
72 /* set pointers */
73 (*c)->algorithm = SRTP_NULL_CIPHER;
74 (*c)->type = &srtp_null_cipher;
75 (*c)->state = (void *)0x1; /* The null cipher does not maintain state */
76
77 /* set key size */
78 (*c)->key_len = key_len;
79
80 return srtp_err_status_ok;
81 }
82
srtp_null_cipher_dealloc(srtp_cipher_t * c)83 static srtp_err_status_t srtp_null_cipher_dealloc(srtp_cipher_t *c)
84 {
85 extern const srtp_cipher_type_t srtp_null_cipher;
86
87 /* zeroize entire state*/
88 octet_string_set_to_zero(c, sizeof(srtp_cipher_t));
89
90 /* free memory of type null_cipher */
91 srtp_crypto_free(c);
92
93 return srtp_err_status_ok;
94 }
95
srtp_null_cipher_init(void * cv,const uint8_t * key)96 static srtp_err_status_t srtp_null_cipher_init(void *cv, const uint8_t *key)
97 {
98 /* srtp_null_cipher_ctx_t *c = (srtp_null_cipher_ctx_t *)cv; */
99
100 debug_print(srtp_mod_cipher, "initializing null cipher", NULL);
101
102 return srtp_err_status_ok;
103 }
104
srtp_null_cipher_set_iv(void * cv,uint8_t * iv,srtp_cipher_direction_t dir)105 static srtp_err_status_t srtp_null_cipher_set_iv(void *cv,
106 uint8_t *iv,
107 srtp_cipher_direction_t dir)
108 {
109 /* srtp_null_cipher_ctx_t *c = (srtp_null_cipher_ctx_t *)cv; */
110 return srtp_err_status_ok;
111 }
112
srtp_null_cipher_encrypt(void * cv,unsigned char * buf,unsigned int * bytes_to_encr)113 static srtp_err_status_t srtp_null_cipher_encrypt(void *cv,
114 unsigned char *buf,
115 unsigned int *bytes_to_encr)
116 {
117 /* srtp_null_cipher_ctx_t *c = (srtp_null_cipher_ctx_t *)cv; */
118 return srtp_err_status_ok;
119 }
120
121 static const char srtp_null_cipher_description[] = "null cipher";
122
123 static const srtp_cipher_test_case_t srtp_null_cipher_test_0 = {
124 0, /* octets in key */
125 NULL, /* key */
126 0, /* packet index */
127 0, /* octets in plaintext */
128 NULL, /* plaintext */
129 0, /* octets in plaintext */
130 NULL, /* ciphertext */
131 0, /* */
132 NULL, /* */
133 0, /* */
134 NULL /* pointer to next testcase */
135 };
136
137 /*
138 * note: the decrypt function is idential to the encrypt function
139 */
140
141 const srtp_cipher_type_t srtp_null_cipher = {
142 srtp_null_cipher_alloc, /* */
143 srtp_null_cipher_dealloc, /* */
144 srtp_null_cipher_init, /* */
145 0, /* set_aad */
146 srtp_null_cipher_encrypt, /* */
147 srtp_null_cipher_encrypt, /* */
148 srtp_null_cipher_set_iv, /* */
149 0, /* get_tag */
150 srtp_null_cipher_description, /* */
151 &srtp_null_cipher_test_0, /* */
152 SRTP_NULL_CIPHER /* */
153 };
154