Alexandre Lision | ddd731e | 2014-01-31 11:50:08 -0500 | [diff] [blame^] | 1 | /* |
| 2 | Copyright (C) 2004-2006 the Minisip Team |
| 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 | |
| 19 | /* Copyright (C) 2004-2012 |
| 20 | * |
| 21 | * Authors: Israel Abad <i_abad@terra.es> |
| 22 | * Erik Eliasson <eliasson@it.kth.se> |
| 23 | * Johan Bilien <jobi@via.ecp.fr> |
| 24 | * Joachim Orrblad <joachim@orrblad.com> |
| 25 | * Werner Dittmann <Werner.Dittmann@t-online.de> |
| 26 | */ |
| 27 | |
| 28 | #include <iostream> |
| 29 | |
| 30 | #include <ccrtp-config.h> |
| 31 | |
| 32 | #ifdef SRTP_SUPPORT |
| 33 | #include <ccrtp/crypto/hmac.h> |
| 34 | #include <ccrtp/crypto/macSkein.h> |
| 35 | #endif |
| 36 | |
| 37 | #include <commoncpp/config.h> |
| 38 | #include <commoncpp/export.h> |
| 39 | #include <ccrtp/CryptoContextCtrl.h> |
| 40 | #include <ccrtp/base.h> |
| 41 | |
| 42 | NAMESPACE_COMMONCPP |
| 43 | |
| 44 | CryptoContextCtrl::CryptoContextCtrl(uint32 ssrc ): |
| 45 | ssrcCtx(ssrc), |
| 46 | using_mki(false),mkiLength(0),mki(NULL), s_l(0), |
| 47 | replay_window(0), |
| 48 | master_key(NULL), master_key_length(0), |
| 49 | master_salt(NULL), master_salt_length(0), |
| 50 | n_e(0),k_e(NULL),n_a(0),k_a(NULL),n_s(0),k_s(NULL), |
| 51 | ealg(SrtpEncryptionNull), aalg(SrtpAuthenticationNull), |
| 52 | ekeyl(0), akeyl(0), skeyl(0), |
| 53 | macCtx(NULL), cipher(NULL), f8Cipher(NULL) |
| 54 | {} |
| 55 | |
| 56 | #ifdef SRTP_SUPPORT |
| 57 | CryptoContextCtrl::CryptoContextCtrl(uint32 ssrc, |
| 58 | const int32 ealg, |
| 59 | const int32 aalg, |
| 60 | uint8* master_key, |
| 61 | int32 master_key_length, |
| 62 | uint8* master_salt, |
| 63 | int32 master_salt_length, |
| 64 | int32 ekeyl, |
| 65 | int32 akeyl, |
| 66 | int32 skeyl, |
| 67 | int32 tagLength): |
| 68 | |
| 69 | ssrcCtx(ssrc),using_mki(false),mkiLength(0),mki(NULL), |
| 70 | replay_window(0), macCtx(NULL), cipher(NULL), f8Cipher(NULL) |
| 71 | { |
| 72 | this->ealg = ealg; |
| 73 | this->aalg = aalg; |
| 74 | this->ekeyl = ekeyl; |
| 75 | this->akeyl = akeyl; |
| 76 | this->skeyl = skeyl; |
| 77 | |
| 78 | this->master_key_length = master_key_length; |
| 79 | this->master_key = new uint8[master_key_length]; |
| 80 | memcpy(this->master_key, master_key, master_key_length); |
| 81 | |
| 82 | this->master_salt_length = master_salt_length; |
| 83 | this->master_salt = new uint8[master_salt_length]; |
| 84 | memcpy(this->master_salt, master_salt, master_salt_length); |
| 85 | |
| 86 | switch( ealg ) { |
| 87 | case SrtpEncryptionNull: |
| 88 | n_e = 0; |
| 89 | k_e = NULL; |
| 90 | n_s = 0; |
| 91 | k_s = NULL; |
| 92 | break; |
| 93 | |
| 94 | case SrtpEncryptionTWOF8: |
| 95 | f8Cipher = new SrtpSymCrypto(SrtpEncryptionTWOF8); |
| 96 | // fall through |
| 97 | |
| 98 | case SrtpEncryptionTWOCM: |
| 99 | n_e = ekeyl; |
| 100 | k_e = new uint8[n_e]; |
| 101 | n_s = skeyl; |
| 102 | k_s = new uint8[n_s]; |
| 103 | cipher = new SrtpSymCrypto(SrtpEncryptionTWOCM); |
| 104 | break; |
| 105 | |
| 106 | case SrtpEncryptionAESF8: |
| 107 | f8Cipher = new SrtpSymCrypto(SrtpEncryptionAESF8); |
| 108 | // fall through |
| 109 | |
| 110 | case SrtpEncryptionAESCM: |
| 111 | n_e = ekeyl; |
| 112 | k_e = new uint8[n_e]; |
| 113 | n_s = skeyl; |
| 114 | k_s = new uint8[n_s]; |
| 115 | cipher = new SrtpSymCrypto(SrtpEncryptionAESCM); |
| 116 | break; |
| 117 | } |
| 118 | |
| 119 | switch( aalg ) { |
| 120 | case SrtpAuthenticationNull: |
| 121 | n_a = 0; |
| 122 | k_a = NULL; |
| 123 | this->tagLength = 0; |
| 124 | break; |
| 125 | |
| 126 | case SrtpAuthenticationSha1Hmac: |
| 127 | case SrtpAuthenticationSkeinHmac: |
| 128 | n_a = akeyl; |
| 129 | k_a = new uint8[n_a]; |
| 130 | this->tagLength = tagLength; |
| 131 | break; |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | #endif |
| 136 | |
| 137 | CryptoContextCtrl::~CryptoContextCtrl(){ |
| 138 | |
| 139 | #ifdef SRTP_SUPPORT |
| 140 | if (mki) |
| 141 | delete [] mki; |
| 142 | |
| 143 | if (master_key_length > 0) { |
| 144 | memset(master_key, 0, master_key_length); |
| 145 | master_key_length = 0; |
| 146 | delete [] master_key; |
| 147 | } |
| 148 | if (master_salt_length > 0) { |
| 149 | memset(master_salt, 0, master_salt_length); |
| 150 | master_salt_length = 0; |
| 151 | delete [] master_salt; |
| 152 | } |
| 153 | if (n_e > 0) { |
| 154 | memset(k_e, 0, n_e); |
| 155 | n_e = 0; |
| 156 | delete [] k_e; |
| 157 | } |
| 158 | if (n_s > 0) { |
| 159 | memset(k_s, 0, n_s); |
| 160 | n_s = 0; |
| 161 | delete [] k_s; |
| 162 | } |
| 163 | if (n_a > 0) { |
| 164 | memset(k_a, 0, n_a); |
| 165 | n_a = 0; |
| 166 | delete [] k_a; |
| 167 | } |
| 168 | if (cipher != NULL) { |
| 169 | delete cipher; |
| 170 | cipher = NULL; |
| 171 | } |
| 172 | if (f8Cipher != NULL) { |
| 173 | delete f8Cipher; |
| 174 | f8Cipher = NULL; |
| 175 | } |
| 176 | if (macCtx != NULL) { |
| 177 | switch(aalg) { |
| 178 | case SrtpAuthenticationSha1Hmac: |
| 179 | freeSha1HmacContext(macCtx); |
| 180 | break; |
| 181 | |
| 182 | case SrtpAuthenticationSkeinHmac: |
| 183 | freeSkeinMacContext(macCtx); |
| 184 | break; |
| 185 | } |
| 186 | } |
| 187 | #endif |
| 188 | |
| 189 | ealg = SrtpEncryptionNull; |
| 190 | aalg = SrtpAuthenticationNull; |
| 191 | } |
| 192 | |
| 193 | void CryptoContextCtrl::srtcpEncrypt( uint8* rtp, size_t len, uint64 index, uint32 ssrc ) |
| 194 | { |
| 195 | if (ealg == SrtpEncryptionNull) { |
| 196 | return; |
| 197 | } |
| 198 | #ifdef SRTP_SUPPORT |
| 199 | if (ealg == SrtpEncryptionAESCM || ealg == SrtpEncryptionTWOCM) { |
| 200 | |
| 201 | /* Compute the CM IV (refer to chapter 4.1.1 in RFC 3711): |
| 202 | * |
| 203 | * k_s XX XX XX XX XX XX XX XX XX XX XX XX XX XX |
| 204 | * SSRC XX XX XX XX |
| 205 | * index XX XX XX XX |
| 206 | * ------------------------------------------------------XOR |
| 207 | * IV XX XX XX XX XX XX XX XX XX XX XX XX XX XX 00 00 |
| 208 | * 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
| 209 | */ |
| 210 | unsigned char iv[16]; |
| 211 | |
| 212 | iv[0] = k_s[0]; |
| 213 | iv[1] = k_s[1]; |
| 214 | iv[2] = k_s[2]; |
| 215 | iv[3] = k_s[3]; |
| 216 | |
| 217 | // The shifts transform the ssrc and index into network order |
| 218 | iv[4] = ((ssrc >> 24) & 0xff) ^ k_s[4]; |
| 219 | iv[5] = ((ssrc >> 16) & 0xff) ^ k_s[5]; |
| 220 | iv[6] = ((ssrc >> 8) & 0xff) ^ k_s[6]; |
| 221 | iv[7] = (ssrc & 0xff) ^ k_s[7]; |
| 222 | |
| 223 | iv[8] = k_s[8]; |
| 224 | iv[9] = k_s[9]; |
| 225 | |
| 226 | iv[10] = ((index >> 24) & 0xff) ^ k_s[10]; |
| 227 | iv[11] = ((index >> 16) & 0xff) ^ k_s[11]; |
| 228 | iv[12] = ((index >> 8) & 0xff) ^ k_s[12]; |
| 229 | iv[13] = (index & 0xff) ^ k_s[13]; |
| 230 | |
| 231 | iv[14] = iv[15] = 0; |
| 232 | |
| 233 | cipher->ctr_encrypt(rtp, len, iv); |
| 234 | } |
| 235 | |
| 236 | if (ealg == SrtpEncryptionAESF8 || ealg == SrtpEncryptionTWOF8) { |
| 237 | |
| 238 | unsigned char iv[16]; |
| 239 | |
| 240 | // 4 bytes of the iv are zero |
| 241 | // the first byte of the RTP header is not used. |
| 242 | iv[0] = 0; |
| 243 | iv[1] = 0; |
| 244 | iv[2] = 0; |
| 245 | iv[3] = 0; |
| 246 | |
| 247 | // Need the encryption flag |
| 248 | index = index | 0x80000000; |
| 249 | |
| 250 | // set the index and the encrypt flag in network order into IV |
| 251 | iv[4] = index >> 24; |
| 252 | iv[5] = index >> 16; |
| 253 | iv[6] = index >> 8; |
| 254 | iv[7] = index; |
| 255 | |
| 256 | // The fixed header follows and fills the rest of the IV |
| 257 | memcpy(iv+8, rtp, 8); |
| 258 | |
| 259 | cipher->f8_encrypt(rtp, len, iv, f8Cipher); |
| 260 | } |
| 261 | #endif |
| 262 | } |
| 263 | |
| 264 | /* Warning: tag must have been initialized */ |
| 265 | void CryptoContextCtrl::srtcpAuthenticate(uint8* rtp, size_t len, uint32 index, uint8* tag ) |
| 266 | { |
| 267 | if (aalg == SrtpAuthenticationNull) { |
| 268 | return; |
| 269 | } |
| 270 | #ifdef SRTP_SUPPORT |
| 271 | int32_t macL; |
| 272 | |
| 273 | unsigned char temp[20]; |
| 274 | const unsigned char* chunks[3]; |
| 275 | unsigned int chunkLength[3]; |
| 276 | uint32_t beIndex = htonl(index); |
| 277 | |
| 278 | chunks[0] = rtp; |
| 279 | chunkLength[0] = len; |
| 280 | |
| 281 | chunks[1] = (unsigned char *)&beIndex; |
| 282 | chunkLength[1] = 4; |
| 283 | chunks[2] = NULL; |
| 284 | |
| 285 | switch (aalg) { |
| 286 | case SrtpAuthenticationSha1Hmac: |
| 287 | hmacSha1Ctx(macCtx, |
| 288 | chunks, // data chunks to hash |
| 289 | chunkLength, // length of the data to hash |
| 290 | temp, &macL); |
| 291 | /* truncate the result */ |
| 292 | memcpy(tag, temp, getTagLength()); |
| 293 | break; |
| 294 | case SrtpAuthenticationSkeinHmac: |
| 295 | macSkeinCtx(macCtx, |
| 296 | chunks, // data chunks to hash |
| 297 | chunkLength, // length of the data to hash |
| 298 | temp); |
| 299 | /* truncate the result */ |
| 300 | memcpy(tag, temp, getTagLength()); |
| 301 | break; |
| 302 | } |
| 303 | #endif |
| 304 | } |
| 305 | |
| 306 | #ifdef SRTP_SUPPORT |
| 307 | /* used by the key derivation method */ |
| 308 | static void computeIv(unsigned char* iv, uint8 label, uint8* master_salt) |
| 309 | { |
| 310 | //printf( "Key_ID: %llx\n", key_id ); |
| 311 | |
| 312 | /* compute the IV |
| 313 | key_id: XX XX XX XX XX XX XX |
| 314 | master_salt: XX XX XX XX XX XX XX XX XX XX XX XX XX XX |
| 315 | ------------------------------------------------------------ XOR |
| 316 | IV: XX XX XX XX XX XX XX XX XX XX XX XX XX XX 00 00 |
| 317 | */ |
| 318 | |
| 319 | memcpy(iv, master_salt, 14); |
| 320 | iv[7] ^= label; |
| 321 | |
| 322 | iv[14] = iv[15] = 0; |
| 323 | } |
| 324 | #endif |
| 325 | |
| 326 | /* Derives the srtp session keys from the master key */ |
| 327 | void CryptoContextCtrl::deriveSrtcpKeys() |
| 328 | { |
| 329 | #ifdef SRTP_SUPPORT |
| 330 | uint8 iv[16]; |
| 331 | |
| 332 | // prepare AES cipher to compute derived keys. |
| 333 | cipher->setNewKey(master_key, master_key_length); |
| 334 | memset(master_key, 0, master_key_length); |
| 335 | |
| 336 | // compute the session encryption key |
| 337 | uint8 label = 3; |
| 338 | computeIv(iv, label, master_salt); |
| 339 | cipher->get_ctr_cipher_stream(k_e, n_e, iv); |
| 340 | |
| 341 | // compute the session authentication key |
| 342 | label = 4; |
| 343 | computeIv(iv, label, master_salt); |
| 344 | cipher->get_ctr_cipher_stream(k_a, n_a, iv); |
| 345 | |
| 346 | // Initialize MAC context with the derived key |
| 347 | switch (aalg) { |
| 348 | case SrtpAuthenticationSha1Hmac: |
| 349 | macCtx = createSha1HmacContext(k_a, n_a); |
| 350 | break; |
| 351 | case SrtpAuthenticationSkeinHmac: |
| 352 | // Skein MAC uses number of bits as MAC size, not just bytes |
| 353 | macCtx = createSkeinMacContext(k_a, n_a, tagLength*8, Skein512); |
| 354 | break; |
| 355 | } |
| 356 | memset(k_a, 0, n_a); |
| 357 | |
| 358 | // compute the session salt |
| 359 | label = 5; |
| 360 | computeIv(iv, label, master_salt); |
| 361 | cipher->get_ctr_cipher_stream(k_s, n_s, iv); |
| 362 | memset(master_salt, 0, master_salt_length); |
| 363 | |
| 364 | // as last step prepare ciphers with derived key. |
| 365 | cipher->setNewKey(k_e, n_e); |
| 366 | if (f8Cipher != NULL) |
| 367 | cipher->f8_deriveForIV(f8Cipher, k_e, n_e, k_s, n_s); |
| 368 | memset(k_e, 0, n_e); |
| 369 | #endif |
| 370 | } |
| 371 | |
| 372 | bool CryptoContextCtrl::checkReplay( uint32 index ) |
| 373 | { |
| 374 | #ifdef SRTP_SUPPORT |
| 375 | if ( aalg == SrtpAuthenticationNull && ealg == SrtpEncryptionNull ) { |
| 376 | /* No security policy, don't use the replay protection */ |
| 377 | return true; |
| 378 | } |
| 379 | |
| 380 | int64 delta = s_l - index; |
| 381 | if (delta > 0) { |
| 382 | /* Packet not yet received*/ |
| 383 | return true; |
| 384 | } |
| 385 | else { |
| 386 | if( -delta > REPLAY_WINDOW_SIZE ) { |
| 387 | /* Packet too old */ |
| 388 | return false; |
| 389 | } |
| 390 | else { |
| 391 | if((replay_window >> (-delta)) & 0x1) { |
| 392 | /* Packet already received ! */ |
| 393 | return false; |
| 394 | } |
| 395 | else { |
| 396 | /* Packet not yet received */ |
| 397 | return true; |
| 398 | } |
| 399 | } |
| 400 | } |
| 401 | #else |
| 402 | return true; |
| 403 | #endif |
| 404 | } |
| 405 | |
| 406 | void CryptoContextCtrl::update(uint32 index) |
| 407 | { |
| 408 | #ifdef SRTP_SUPPORT |
| 409 | int64 delta = index - s_l; |
| 410 | |
| 411 | /* update the replay bitmask */ |
| 412 | if( delta > 0 ){ |
| 413 | replay_window = replay_window << delta; |
| 414 | replay_window |= 1; |
| 415 | } |
| 416 | else { |
| 417 | replay_window |= ( 1 << delta ); |
| 418 | } |
| 419 | s_l = index; |
| 420 | |
| 421 | #endif |
| 422 | } |
| 423 | |
| 424 | CryptoContextCtrl* CryptoContextCtrl::newCryptoContextForSSRC(uint32 ssrc) |
| 425 | { |
| 426 | #ifdef SRTP_SUPPORT |
| 427 | CryptoContextCtrl* pcc = new CryptoContextCtrl( |
| 428 | ssrc, |
| 429 | this->ealg, // encryption algo |
| 430 | this->aalg, // authentication algo |
| 431 | this->master_key, // Master Key |
| 432 | this->master_key_length, // Master Key length |
| 433 | this->master_salt, // Master Salt |
| 434 | this->master_salt_length, // Master Salt length |
| 435 | this->ekeyl, // encryption keyl |
| 436 | this->akeyl, // authentication key len |
| 437 | this->skeyl, // session salt len |
| 438 | this->tagLength); // authentication tag len |
| 439 | |
| 440 | return pcc; |
| 441 | #else |
| 442 | return NULL; |
| 443 | #endif |
| 444 | } |
| 445 | |
| 446 | END_NAMESPACE |
| 447 | |
| 448 | /** EMACS ** |
| 449 | * Local variables: |
| 450 | * mode: c++ |
| 451 | * c-default-style: ellemtel |
| 452 | * c-basic-offset: 4 |
| 453 | * End: |
| 454 | */ |
| 455 | |