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comparison: netwerk/srtp/src/include/ekt.h

netwerk/srtp/src/include/ekt.h

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1 /*
2 * ekt.h
3 *
4 * interface to Encrypted Key Transport for SRTP
5 *
6 * David McGrew
7 * Cisco Systems, Inc.
8 */
9 /*
10 *
11 * Copyright (c) 2001-2005 Cisco Systems, Inc.
12 * All rights reserved.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 *
18 * Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 *
21 * Redistributions in binary form must reproduce the above
22 * copyright notice, this list of conditions and the following
23 * disclaimer in the documentation and/or other materials provided
24 * with the distribution.
25 *
26 * Neither the name of the Cisco Systems, Inc. nor the names of its
27 * contributors may be used to endorse or promote products derived
28 * from this software without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
31 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
32 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
33 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
34 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
35 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
36 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
37 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
41 * OF THE POSSIBILITY OF SUCH DAMAGE.
42 *
43 */
44
45
46
47 /*
48 * EKT implementation strategy
49 *
50 * use stream_template approach
51 *
52 * in srtp_unprotect, when a new stream appears, check if template has
53 * EKT defined, and if it does, then apply EKT processing
54 *
55 * question: will we want to allow key-sharing templates in addition
56 * to EKT templates? could define a new ssrc_type_t that's associated
57 * with an EKT, e.g. ssrc_any_ekt.
58 *
59 *
60 */
61
62 #ifndef EKT_H
63 #define EKT_H
64
65 #ifdef __cplusplus
66 extern "C" {
67 #endif
68
69 #include "srtp_priv.h"
70
71 #define EKT_CIPHER_DEFAULT 1
72 #define EKT_CIPHER_AES_128_ECB 1
73 #define EKT_CIPHER_AES_192_KEY_WRAP 2
74 #define EKT_CIPHER_AES_256_KEY_WRAP 3
75
76 typedef uint16_t ekt_spi_t;
77
78
79 unsigned
80 ekt_octets_after_base_tag(ekt_stream_t ekt);
81
82 /*
83 * an srtp_policy_t structure can contain a pointer to an
84 * ekt_policy_t structure
85 *
86 * this structure holds all of the high level EKT information, and it
87 * is passed into libsrtp to indicate what policy should be in effect
88 */
89
90 typedef struct ekt_policy_ctx_t {
91 ekt_spi_t spi; /* security parameter index */
92 uint8_t ekt_cipher_type;
93 uint8_t *ekt_key;
94 struct ekt_policy_ctx_t *next_ekt_policy;
95 } ekt_policy_ctx_t;
96
97
98 /*
99 * an ekt_data_t structure holds the data corresponding to an ekt key,
100 * spi, and so on
101 */
102
103 typedef struct ekt_data_t {
104 ekt_spi_t spi;
105 uint8_t ekt_cipher_type;
106 aes_expanded_key_t ekt_enc_key;
107 aes_expanded_key_t ekt_dec_key;
108 struct ekt_data_t *next_ekt_data;
109 } ekt_data_t;
110
111 /*
112 * an srtp_stream_ctx_t can contain an ekt_stream_ctx_t
113 *
114 * an ekt_stream_ctx_t structure holds all of the EKT information for
115 * a specific SRTP stream
116 */
117
118 typedef struct ekt_stream_ctx_t {
119 ekt_data_t *data;
120 uint16_t isn; /* initial sequence number */
121 uint8_t encrypted_master_key[SRTP_MAX_KEY_LEN];
122 } ekt_stream_ctx_t;
123
124
125
126 err_status_t
127 ekt_alloc(ekt_stream_t *stream_data, ekt_policy_t policy);
128
129 err_status_t
130 ekt_stream_init(ekt_stream_t e,
131 ekt_spi_t spi,
132 void *ekt_key,
133 unsigned ekt_cipher_type);
134
135 err_status_t
136 ekt_stream_init_from_policy(ekt_stream_t e, ekt_policy_t p);
137
138
139
140 err_status_t
141 srtp_stream_init_from_ekt(srtp_stream_t stream,
142 const void *srtcp_hdr,
143 unsigned pkt_octet_len);
144
145
146 void
147 ekt_write_data(ekt_stream_t ekt,
148 uint8_t *base_tag,
149 unsigned base_tag_len,
150 int *packet_len,
151 xtd_seq_num_t pkt_index);
152
153 /*
154 * We handle EKT by performing some additional steps before
155 * authentication (copying the auth tag into a temporary location,
156 * zeroizing the "base tag" field in the packet)
157 *
158 * With EKT, the tag_len parameter is actually the base tag
159 * length
160 */
161
162 err_status_t
163 ekt_tag_verification_preproces(uint8_t *pkt_tag,
164 uint8_t *pkt_tag_copy,
165 unsigned tag_len);
166
167 err_status_t
168 ekt_tag_verification_postproces(uint8_t *pkt_tag,
169 uint8_t *pkt_tag_copy,
170 unsigned tag_len);
171
172
173 /*
174 * @brief EKT pre-processing for srtcp tag generation
175 *
176 * This function does the pre-processing of the SRTCP authentication
177 * tag format. When EKT is used, it consists of writing the Encrypted
178 * Master Key, the SRTP ROC, the Initial Sequence Number, and SPI
179 * fields. The Base Authentication Tag field is set to the all-zero
180 * value
181 *
182 * When EKT is not used, this function is a no-op.
183 *
184 */
185
186 err_status_t
187 srtp_stream_srtcp_auth_tag_generation_preprocess(const srtp_stream_t *s,
188 uint8_t *pkt_tag,
189 unsigned pkt_octet_len);
190
191 /* it's not clear that a tag_generation_postprocess function is needed */
192
193 err_status_t
194 srtcp_auth_tag_generation_postprocess(void);
195
196
197 #ifdef __cplusplus
198 }
199 #endif
200
201 #endif /* EKT_H */

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