1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
|
/*
* cipher.h
*
* common interface to ciphers
*
* 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.
*
*/
#ifndef SRTP_CIPHER_H
#define SRTP_CIPHER_H
#include "srtp.h"
#include "crypto_types.h" /* for values of cipher_type_id_t */
#ifdef __cplusplus
extern "C" {
#endif
/*
* srtp_cipher_direction_t defines a particular cipher operation.
*
* A srtp_cipher_direction_t is an enum that describes a particular cipher
* operation, i.e. encryption or decryption. For some ciphers, this
* distinction does not matter, but for others, it is essential.
*/
typedef enum {
srtp_direction_encrypt, /**< encryption (convert plaintext to ciphertext) */
srtp_direction_decrypt, /**< decryption (convert ciphertext to plaintext) */
srtp_direction_any /**< encryption or decryption */
} srtp_cipher_direction_t;
/*
* the srtp_cipher_pointer_t definition is needed
* as srtp_cipher_t is not yet defined
*/
typedef struct srtp_cipher_t *srtp_cipher_pointer_t;
/*
* a srtp_cipher_alloc_func_t allocates (but does not initialize) a
* srtp_cipher_t
*/
typedef srtp_err_status_t (*srtp_cipher_alloc_func_t)(srtp_cipher_pointer_t *cp,
int key_len,
int tag_len);
/*
* a srtp_cipher_init_func_t [re-]initializes a cipher_t with a given key
*/
typedef srtp_err_status_t (*srtp_cipher_init_func_t)(void *state,
const uint8_t *key);
/* a srtp_cipher_dealloc_func_t de-allocates a cipher_t */
typedef srtp_err_status_t (*srtp_cipher_dealloc_func_t)(
srtp_cipher_pointer_t cp);
/*
* a srtp_cipher_set_aad_func_t processes the AAD data for AEAD ciphers
*/
typedef srtp_err_status_t (*srtp_cipher_set_aad_func_t)(void *state,
const uint8_t *aad,
uint32_t aad_len);
/* a srtp_cipher_encrypt_func_t encrypts data in-place */
typedef srtp_err_status_t (*srtp_cipher_encrypt_func_t)(
void *state,
uint8_t *buffer,
unsigned int *octets_to_encrypt);
/* a srtp_cipher_decrypt_func_t decrypts data in-place */
typedef srtp_err_status_t (*srtp_cipher_decrypt_func_t)(
void *state,
uint8_t *buffer,
unsigned int *octets_to_decrypt);
/*
* a srtp_cipher_set_iv_func_t function sets the current initialization vector
*/
typedef srtp_err_status_t (*srtp_cipher_set_iv_func_t)(
void *state,
uint8_t *iv,
srtp_cipher_direction_t direction);
/*
* a cipher_get_tag_func_t function is used to get the authentication
* tag that was calculated by an AEAD cipher.
*/
typedef srtp_err_status_t (*srtp_cipher_get_tag_func_t)(void *state,
uint8_t *tag,
uint32_t *len);
/*
* srtp_cipher_test_case_t is a (list of) key, salt, plaintext, ciphertext,
* and aad values that are known to be correct for a
* particular cipher. this data can be used to test an implementation
* in an on-the-fly self test of the correctness of the implementation.
* (see the srtp_cipher_type_self_test() function below)
*/
typedef struct srtp_cipher_test_case_t {
int key_length_octets; /* octets in key */
const uint8_t *key; /* key */
uint8_t *idx; /* packet index */
unsigned int plaintext_length_octets; /* octets in plaintext */
const uint8_t *plaintext; /* plaintext */
unsigned int ciphertext_length_octets; /* octets in plaintext */
const uint8_t *ciphertext; /* ciphertext */
int aad_length_octets; /* octets in AAD */
const uint8_t *aad; /* AAD */
int tag_length_octets; /* Length of AEAD tag */
const struct srtp_cipher_test_case_t
*next_test_case; /* pointer to next testcase */
} srtp_cipher_test_case_t;
/* srtp_cipher_type_t defines the 'metadata' for a particular cipher type */
typedef struct srtp_cipher_type_t {
srtp_cipher_alloc_func_t alloc;
srtp_cipher_dealloc_func_t dealloc;
srtp_cipher_init_func_t init;
srtp_cipher_set_aad_func_t set_aad;
srtp_cipher_encrypt_func_t encrypt;
srtp_cipher_encrypt_func_t decrypt;
srtp_cipher_set_iv_func_t set_iv;
srtp_cipher_get_tag_func_t get_tag;
const char *description;
const srtp_cipher_test_case_t *test_data;
srtp_cipher_type_id_t id;
} srtp_cipher_type_t;
/*
* srtp_cipher_t defines an instantiation of a particular cipher, with fixed
* key length, key and salt values
*/
typedef struct srtp_cipher_t {
const srtp_cipher_type_t *type;
void *state;
int key_len;
int algorithm;
} srtp_cipher_t;
/* some bookkeeping functions */
int srtp_cipher_get_key_length(const srtp_cipher_t *c);
/*
* srtp_cipher_type_self_test() tests a cipher against test cases provided in
* an array of values of key/srtp_xtd_seq_num_t/plaintext/ciphertext
* that is known to be good
*/
srtp_err_status_t srtp_cipher_type_self_test(const srtp_cipher_type_t *ct);
/*
* srtp_cipher_type_test() tests a cipher against external test cases provided
* in
* an array of values of key/srtp_xtd_seq_num_t/plaintext/ciphertext
* that is known to be good
*/
srtp_err_status_t srtp_cipher_type_test(
const srtp_cipher_type_t *ct,
const srtp_cipher_test_case_t *test_data);
/*
* srtp_cipher_bits_per_second(c, l, t) computes (an estimate of) the
* number of bits that a cipher implementation can encrypt in a second
*
* c is a cipher (which MUST be allocated and initialized already), l
* is the length in octets of the test data to be encrypted, and t is
* the number of trials
*
* if an error is encountered, then the value 0 is returned
*/
uint64_t srtp_cipher_bits_per_second(srtp_cipher_t *c,
int octets_in_buffer,
int num_trials);
srtp_err_status_t srtp_cipher_type_alloc(const srtp_cipher_type_t *ct,
srtp_cipher_t **c,
int key_len,
int tlen);
srtp_err_status_t srtp_cipher_dealloc(srtp_cipher_t *c);
srtp_err_status_t srtp_cipher_init(srtp_cipher_t *c, const uint8_t *key);
srtp_err_status_t srtp_cipher_set_iv(srtp_cipher_t *c,
uint8_t *iv,
int direction);
srtp_err_status_t srtp_cipher_output(srtp_cipher_t *c,
uint8_t *buffer,
uint32_t *num_octets_to_output);
srtp_err_status_t srtp_cipher_encrypt(srtp_cipher_t *c,
uint8_t *buffer,
uint32_t *num_octets_to_output);
srtp_err_status_t srtp_cipher_decrypt(srtp_cipher_t *c,
uint8_t *buffer,
uint32_t *num_octets_to_output);
srtp_err_status_t srtp_cipher_get_tag(srtp_cipher_t *c,
uint8_t *buffer,
uint32_t *tag_len);
srtp_err_status_t srtp_cipher_set_aad(srtp_cipher_t *c,
const uint8_t *aad,
uint32_t aad_len);
/*
* srtp_replace_cipher_type(ct, id)
*
* replaces srtp's existing cipher implementation for the cipher_type id
* with a new one passed in externally. The new cipher must pass all the
* existing cipher_type's self tests as well as its own.
*/
srtp_err_status_t srtp_replace_cipher_type(const srtp_cipher_type_t *ct,
srtp_cipher_type_id_t id);
#ifdef __cplusplus
}
#endif
#endif /* SRTP_CIPHER_H */
|
