Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 1 | /* |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 2 | Copyright (C) 2006 - 2012 Werner Dittmann |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 3 | |
| 4 | This library is free software; you can redistribute it and/or |
| 5 | modify it under the terms of the GNU Lesser General Public |
| 6 | License as published by the Free Software Foundation; either |
| 7 | version 2.1 of the License, or (at your option) any later version. |
| 8 | |
| 9 | This library is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | Lesser General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU Lesser General Public |
| 15 | License along with this library; if not, write to the Free Software |
| 16 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 17 | */ |
| 18 | |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 19 | #ifndef CRYPTOCONTEXT_H |
| 20 | #define CRYPTOCONTEXT_H |
| 21 | |
| 22 | /** |
| 23 | * @file CryptoContext.h |
| 24 | * @brief The C++ SRTP implementation |
| 25 | * @ingroup Z_SRTP |
| 26 | * @{ |
| 27 | */ |
| 28 | |
| 29 | #define REPLAY_WINDOW_SIZE 64 |
| 30 | |
| 31 | const int SrtpAuthenticationNull = 0; |
| 32 | const int SrtpAuthenticationSha1Hmac = 1; |
| 33 | const int SrtpAuthenticationSkeinHmac = 2; |
| 34 | |
| 35 | const int SrtpEncryptionNull = 0; |
| 36 | const int SrtpEncryptionAESCM = 1; |
| 37 | const int SrtpEncryptionAESF8 = 2; |
| 38 | const int SrtpEncryptionTWOCM = 3; |
| 39 | const int SrtpEncryptionTWOF8 = 4; |
| 40 | |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 41 | // Check if included via CryptoContextCtrl.cpp - avoid double definitions |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 42 | #ifndef CRYPTOCONTEXTCTRL_H |
| 43 | |
| 44 | #include <stdint.h> |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 45 | |
| 46 | class SrtpSymCrypto; |
| 47 | |
| 48 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 49 | * @brief Implementation for a SRTP cryptographic context. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 50 | * |
| 51 | * This class holds data and provides functions that implement a |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 52 | * cryptographic context for SRTP. Refer to RFC 3711, chapter 3.2 for some |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 53 | * more detailed information about the SRTP cryptographic context. |
| 54 | * |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 55 | * Each SRTP cryptographic context uses a RTP source identified by |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 56 | * its SSRC. Thus you can independently protect each source inside a RTP |
| 57 | * session. |
| 58 | * |
| 59 | * Key management mechanisms negotiate the parameters for the SRTP |
| 60 | * cryptographic context, such as master key, key length, authentication |
| 61 | * length and so on. The key management mechanisms are not part of |
| 62 | * SRTP. Refer to MIKEY (RFC 3880) or to Phil Zimmermann's ZRTP protocol |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 63 | * (RFC6189). After key management negotiated the data the application can |
| 64 | * setup the SRTP cryptographic context and enable SRTP processing. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 65 | * |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 66 | * This SRTP context implementation supports RTP only. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 67 | * |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 68 | * A short eample how to setup a SRTP CryptoContext: |
| 69 | @verbatim |
| 70 | |
| 71 | // First some key and salt data - this data is just for demo purposes |
| 72 | uint8 masterKey[] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, |
| 73 | 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f }; |
| 74 | |
| 75 | uint8 masterSalt[] = { 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, |
| 76 | 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d }; |
| 77 | |
| 78 | ... |
| 79 | |
| 80 | CryptoContext* cryptoCtxSend = |
| 81 | new CryptoContext(0xfeedbacc, |
| 82 | 0, // roc, |
| 83 | 0L, // keyderivation rate << 48, |
| 84 | SrtpEncryptionAESCM, // encryption algo |
| 85 | SrtpAuthenticationSha1Hmac, // authtication algo |
| 86 | masterKey, // Master Key data |
| 87 | 128 / 8, // Master Key length in bytes |
| 88 | masterSalt, // Master Salt data |
| 89 | 112 / 8, // Master Salt length in bytes |
| 90 | 128 / 8, // encryption keylength in bytes |
| 91 | 160 / 8, // authentication key length in bytes (SHA1) |
| 92 | 112 / 8, // session salt length in bytes |
| 93 | 80 / 8); // authentication tag length in bytes |
| 94 | |
| 95 | cryptoCtxSend->deriveSrtpKeys(0); |
| 96 | |
| 97 | .... |
| 98 | |
| 99 | // To protect a RTP packet |
| 100 | // buffer: pointer to the RTP packet, length of the RTP data, newLength is a |
| 101 | // pointer to a size_t that gets the updated length. |
| 102 | bool rc = SrtpHandler::protect(cryptoCtxSend, buffer, length, newLength); |
| 103 | |
| 104 | // To unprotect a SRTP packet: |
| 105 | // buffer: pointer to the RTP packet, length of the SRTP data, newLength is a |
| 106 | // pointer to a size_t that gets the updated length. |
| 107 | int32_t rc = SrtpHandler::unprotect(cryptoCtxRecv, buffer, length, newLength); |
| 108 | |
| 109 | @endverbatim |
| 110 | * |
| 111 | * @note You need two CryptoContext instances - one for the sending channel the |
| 112 | * other one for the receiving channel. |
| 113 | * |
| 114 | * Before an appliction can use a CryptoContext it must call the key derivation |
| 115 | * function deriveSrtpKeys() first. Only then this SRTP cryptographic context is ready |
| 116 | * to protect or unprotect a RTP SSRC stream. |
| 117 | * |
| 118 | * Together with the newCryptoContextForSSRC() function an application can prepare a |
| 119 | * CryptoContext and save it as template. Once it needs a new CryptoContext, say |
| 120 | * for a new SSRC, it calls newCryptoContextForSSRC() on the saved context to get an |
| 121 | * initialized copy and then call deriveSrtpKeys() to compute and process the keys. |
| 122 | * |
| 123 | * @note A saved, pre-initialized template contains the non-processed keys. Only |
| 124 | * the method deriveSrtpKeys() processes the keys and cleares them. Thus don't store |
| 125 | * CryptoContext templates if the application cannot protect the templates against |
| 126 | * reading from other possibly rogue applications. |
| 127 | * |
| 128 | * @sa SrtpHandler |
| 129 | * |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 130 | * @author Werner Dittmann <Werner.Dittmann@t-online.de> |
| 131 | */ |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 132 | class CryptoContext { |
| 133 | public: |
| 134 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 135 | * @brief Constructor for an active SRTP cryptographic context. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 136 | * |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 137 | * This constructor creates an pre-initialized SRTP cryptographic context were |
| 138 | * algorithms are allocated, keys are stored and so on. An application can |
| 139 | * call newCryptoContextForSSRC() to get a full copy of this pre-initialized |
| 140 | * CryptoContext. |
| 141 | * |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 142 | * |
| 143 | * @param ssrc |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 144 | * The RTP SSRC that this SRTP cryptographic context belongs to. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 145 | * |
| 146 | * @param roc |
| 147 | * The initial Roll-Over-Counter according to RFC 3711. These are the |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 148 | * upper 32 bit of the overall 48 bit SRTP packet index. Usually set to zero. |
| 149 | * Refer to chapter 3.2.1 of the RFC. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 150 | * |
| 151 | * @param keyDerivRate |
| 152 | * The key derivation rate defines when to recompute the SRTP session |
| 153 | * keys. Refer to chapter 4.3.1 in the RFC. |
| 154 | * |
| 155 | * @param ealg |
| 156 | * The encryption algorithm to use. Possible values are <code> |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 157 | * SrtpEncryptionNull, SrtpEncryptionAESCM, SrtpEncryptionAESF8, |
| 158 | * SrtpEncryptionTWOCM, SrtpEncryptionTWOF8</code>. See chapter 4.1.1 |
| 159 | * for AESCM (Counter mode) and 4.1.2 for AES F8 mode. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 160 | * |
| 161 | * @param aalg |
| 162 | * The authentication algorithm to use. Possible values are <code> |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 163 | * SrtpEncryptionNull, SrtpAuthenticationSha1Hmac, SrtpAuthenticationSkeinHmac |
| 164 | * </code>. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 165 | * |
| 166 | * @param masterKey |
| 167 | * Pointer to the master key for this SRTP cryptographic context. |
| 168 | * Must point to <code>masterKeyLength</code> bytes. Refer to chapter |
| 169 | * 3.2.1 of the RFC about the role of the master key. |
| 170 | * |
| 171 | * @param masterKeyLength |
| 172 | * The length in bytes of the master key in bytes. The length must |
| 173 | * match the selected encryption algorithm. Because SRTP uses AES |
| 174 | * based encryption only, then master key length may be 16 or 32 |
| 175 | * bytes (128 or 256 bit master key) |
| 176 | * |
| 177 | * @param masterSalt |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 178 | * SRTP uses the master salt to generate the initialization vector |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 179 | * that in turn is input to compute the session key, session |
| 180 | * authentication key and the session salt. |
| 181 | * |
| 182 | * @param masterSaltLength |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 183 | * The length in bytes of the master salt data in bytes. According to |
| 184 | * RFC3711 the standard value for the master salt length should |
| 185 | * be 14 bytes (112 bit). |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 186 | * |
| 187 | * @param ekeyl |
| 188 | * The length in bytes of the session encryption key that SRTP shall |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 189 | * generate and use. Usually the same length as for the master key |
| 190 | * length, however you may use a different length as well. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 191 | * |
| 192 | * @param akeyl |
| 193 | * The length in bytes of the session authentication key. SRTP |
| 194 | * computes this key and uses it as input to the authentication |
| 195 | * algorithm. |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 196 | * This is usually 160 bits (20 bytes) for @c SrtpAuthenticationSha1Hmac |
| 197 | * and 256 bits (32 bytes) for @c SrtpAuthenticationSkeinHmac. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 198 | * |
| 199 | * @param skeyl |
| 200 | * The length in bytes of the session salt. SRTP computes this salt |
| 201 | * key and uses it as input during encryption. The length usually |
| 202 | * is the same as the master salt length. |
| 203 | * |
| 204 | * @param tagLength |
| 205 | * The length is bytes of the authentication tag that SRTP appends |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 206 | * to the RTP packet. The @c CryptoContext supports @c SrtpAuthenticationSha1Hmac |
| 207 | * with 4 and 10 byte (32 and 80 bits) and @c SrtpAuthenticationSkeinHmac |
| 208 | * with 4 and 8 bytes (32 and 64 bits) tag length. Refer to chapter 4.2. in RFC 3711. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 209 | */ |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 210 | CryptoContext(uint32_t ssrc, int32_t roc, |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 211 | int64_t keyDerivRate, |
| 212 | const int32_t ealg, |
| 213 | const int32_t aalg, |
| 214 | uint8_t* masterKey, |
| 215 | int32_t masterKeyLength, |
| 216 | uint8_t* masterSalt, |
| 217 | int32_t masterSaltLength, |
| 218 | int32_t ekeyl, |
| 219 | int32_t akeyl, |
| 220 | int32_t skeyl, |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 221 | int32_t tagLength); |
| 222 | |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 223 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 224 | * @brief Destructor. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 225 | * |
| 226 | * Cleans the SRTP cryptographic context. |
| 227 | */ |
| 228 | ~CryptoContext(); |
| 229 | |
| 230 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 231 | * @brief Set the Roll-Over-Counter. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 232 | * |
| 233 | * Ths method sets the upper 32 bit of the 48 bit SRTP packet index |
| 234 | * (the roll-over-part) |
| 235 | * |
| 236 | * @param r |
| 237 | * The roll-over-counter |
| 238 | */ |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 239 | inline void setRoc(uint32_t r) { roc = r; } |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 240 | |
| 241 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 242 | * @brief Get the Roll-Over-Counter. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 243 | * |
| 244 | * Ths method get the upper 32 bit of the 48 bit SRTP packet index |
| 245 | * (the roll-over-part) |
| 246 | * |
| 247 | * @return The roll-over-counter |
| 248 | */ |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 249 | inline uint32_t getRoc() const { return roc; } |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 250 | |
| 251 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 252 | * @brief Perform SRTP encryption. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 253 | * |
| 254 | * This method encrypts <em>and</em> decrypts SRTP payload data. Plain |
| 255 | * data gets encrypted, encrypted data get decrypted. |
| 256 | * |
| 257 | * @param pkt |
| 258 | * Pointer to RTP packet buffer, used for F8. |
| 259 | * |
| 260 | * @param payload |
| 261 | * The data to encrypt. |
| 262 | * |
| 263 | * @param paylen |
| 264 | * Length of payload. |
| 265 | * |
| 266 | * @param index |
| 267 | * The 48 bit SRTP packet index. See the <code>guessIndex</code> |
| 268 | * method. |
| 269 | * |
| 270 | * @param ssrc |
| 271 | * The RTP SSRC data in <em>host</em> order. |
| 272 | */ |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 273 | void srtpEncrypt(uint8_t* pkt, uint8_t* payload, uint32_t paylen, uint64_t index, uint32_t ssrc); |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 274 | |
| 275 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 276 | * @brief Compute the authentication tag. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 277 | * |
| 278 | * Compute the authentication tag according the the paramters in the |
| 279 | * SRTP Cryptograhic context. |
| 280 | * |
| 281 | * @param pkt |
| 282 | * Pointer to RTP packet buffer that contains the data to authenticate. |
| 283 | * |
| 284 | * @param pktlen |
| 285 | * Length of the RTP packet buffer |
| 286 | * |
| 287 | * @param roc |
| 288 | * The 32 bit SRTP roll-over-counter. |
| 289 | * |
| 290 | * @param tag |
| 291 | * Points to a buffer that hold the computed tag. This buffer must |
| 292 | * be able to hold <code>tagLength</code> bytes. |
| 293 | */ |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 294 | void srtpAuthenticate(uint8_t* pkt, uint32_t pktlen, uint32_t roc, uint8_t* tag); |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 295 | |
| 296 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 297 | * @brief Perform key derivation according to SRTP specification |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 298 | * |
| 299 | * This method computes the session key, session authentication key and the |
| 300 | * session salt key. This method must be called at least once after the |
| 301 | * SRTP Cryptograhic context was set up. |
| 302 | * |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 303 | * This method clears the key data once it was processed by the encryptions' |
| 304 | * set key functions. |
| 305 | * |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 306 | * @param index |
| 307 | * The 48 bit SRTP packet index. See the <code>guessIndex</code> |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 308 | * method. Usually 0. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 309 | */ |
| 310 | void deriveSrtpKeys(uint64_t index); |
| 311 | |
| 312 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 313 | * @brief Compute (guess) the new SRTP index based on the sequence number of |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 314 | * a received RTP packet. |
| 315 | * |
| 316 | * The method uses the algorithm show in RFC3711, Appendix A, to compute |
| 317 | * the new index. |
| 318 | * |
| 319 | * @param newSeqNumber |
| 320 | * The sequence number of the received RTP packet in host order. |
| 321 | * |
| 322 | * @return The new SRTP packet index |
| 323 | */ |
| 324 | uint64_t guessIndex(uint16_t newSeqNumber); |
| 325 | |
| 326 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 327 | * @brief Check for packet replay. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 328 | * |
| 329 | * The method check if a received packet is either to old or was already |
| 330 | * received. |
| 331 | * |
| 332 | * The method supports a 64 packet history relative the the given |
| 333 | * sequence number. |
| 334 | * |
| 335 | * @param newSeqNumber |
| 336 | * The sequence number of the received RTP packet in host order. |
| 337 | * |
| 338 | * @return <code>true</code> if no replay, <code>false</code> if packet |
| 339 | * is too old ar was already received. |
| 340 | */ |
| 341 | bool checkReplay(uint16_t newSeqNumber); |
| 342 | |
| 343 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 344 | * @brief Update the SRTP packet index. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 345 | * |
| 346 | * Call this method after all checks were successful. See chapter |
| 347 | * 3.3.1 in the RFC when to update the ROC and ROC processing. |
| 348 | * |
| 349 | * @param newSeqNumber |
| 350 | * The sequence number of the received RTP packet in host order. |
| 351 | */ |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 352 | void update(uint16_t newSeqNumber); |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 353 | |
| 354 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 355 | * @brief Get the length of the SRTP authentication tag in bytes. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 356 | * |
| 357 | * @return the length of the authentication tag. |
| 358 | */ |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 359 | int32_t getTagLength() const { return tagLength; } |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 360 | |
| 361 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 362 | * @brief Get the length of the MKI in bytes. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 363 | * |
| 364 | * @return the length of the MKI. |
| 365 | */ |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 366 | int32_t getMkiLength() const { return mkiLength; } |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 367 | |
| 368 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 369 | * @brief Get the SSRC of this SRTP Cryptograhic context. |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 370 | * |
| 371 | * @return the SSRC. |
| 372 | */ |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 373 | uint32_t getSsrc() const { return ssrcCtx; } |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 374 | |
| 375 | /** |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 376 | * @brief Set the start (base) number to compute the PRF labels. |
| 377 | * |
| 378 | * Refer to RFC3711, chapters 4.3.1 and 4.3.2 about values for labels. |
| 379 | * CryptoContext computes the labes as follows: |
| 380 | * |
| 381 | * - labelBase + 0 -> encryption label |
| 382 | * - labelBase + 1 -> authentication label |
| 383 | * - labelBase + 2 -> salting key label |
| 384 | * |
| 385 | * The CryptoContext constructor initializes CryptoContext::labelBase |
| 386 | * with 0 to comply with RFC 3711 label values. |
| 387 | * |
| 388 | * Applications may set the #labelBase to other values to use the CryptoContext |
| 389 | * for other purposes. |
| 390 | */ |
| 391 | void setLabelbase(uint8_t base) { labelBase = base; } |
| 392 | |
| 393 | /** |
| 394 | * @brief Derive a new Crypto Context for use with a new SSRC |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 395 | * |
| 396 | * This method returns a new Crypto Context initialized with the data |
| 397 | * of this crypto context. Replacing the SSRC, Roll-over-Counter, and |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 398 | * the key derivation rate the application can use this Crypto Context |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 399 | * to encrypt / decrypt a new stream (Synchronization source) inside |
| 400 | * one RTP session. |
| 401 | * |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 402 | * Before the application can use this crypto context it must call deriveSrtpKeys(). |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 403 | * |
| 404 | * @param ssrc |
| 405 | * The SSRC for this context |
| 406 | * @param roc |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 407 | * The Roll-Over-Counter for this context, usually 0 |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 408 | * @param keyDerivRate |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 409 | * The key derivation rate for this context, usally 0 |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 410 | * @return |
| 411 | * a new CryptoContext with all relevant data set. |
| 412 | */ |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 413 | CryptoContext* newCryptoContextForSSRC(uint32_t ssrc, int roc, int64_t keyDerivRate); |
| 414 | |
| 415 | private: |
| 416 | |
| 417 | uint32_t ssrcCtx; |
| 418 | bool using_mki; |
| 419 | uint32_t mkiLength; |
| 420 | uint8_t* mki; |
| 421 | |
| 422 | uint32_t roc; |
| 423 | uint32_t guessed_roc; |
| 424 | uint16_t s_l; |
| 425 | int64_t key_deriv_rate; |
| 426 | |
| 427 | /* bitmask for replay check */ |
| 428 | uint64_t replay_window; |
| 429 | |
| 430 | uint8_t* master_key; |
| 431 | uint32_t master_key_length; |
| 432 | uint32_t master_key_srtp_use_nb; |
| 433 | uint32_t master_key_srtcp_use_nb; |
| 434 | uint8_t* master_salt; |
| 435 | uint32_t master_salt_length; |
| 436 | |
| 437 | /* Session Encryption, Authentication keys, Salt */ |
| 438 | int32_t n_e; |
| 439 | uint8_t* k_e; |
| 440 | int32_t n_a; |
| 441 | uint8_t* k_a; |
| 442 | int32_t n_s; |
| 443 | uint8_t* k_s; |
| 444 | |
| 445 | int32_t ealg; |
| 446 | int32_t aalg; |
| 447 | int32_t ekeyl; |
| 448 | int32_t akeyl; |
| 449 | int32_t skeyl; |
| 450 | int32_t tagLength; |
Alexandre Lision | 7fd5d3d | 2013-12-04 13:06:40 -0500 | [diff] [blame] | 451 | uint8_t labelBase; |
Alexandre Lision | 51140e1 | 2013-12-02 10:54:09 -0500 | [diff] [blame] | 452 | bool seqNumSet; |
| 453 | |
| 454 | void* macCtx; |
| 455 | |
| 456 | SrtpSymCrypto* cipher; |
| 457 | SrtpSymCrypto* f8Cipher; |
| 458 | }; |
| 459 | |
| 460 | #endif |
| 461 | |
| 462 | /** |
| 463 | * @} |
| 464 | */ |
| 465 | #endif |
| 466 | |