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1 <?php 2 3 /** 4 * Pure-PHP implementation of Triple DES. 5 * 6 * Uses mcrypt, if available, and an internal implementation, otherwise. Operates in the EDE3 mode (encrypt-decrypt-encrypt). 7 * 8 * PHP version 5 9 * 10 * Here's a short example of how to use this library: 11 * <code> 12 * <?php 13 * include 'vendor/autoload.php'; 14 * 15 * $des = new \phpseclib\Crypt\TripleDES(); 16 * 17 * $des->setKey('abcdefghijklmnopqrstuvwx'); 18 * 19 * $size = 10 * 1024; 20 * $plaintext = ''; 21 * for ($i = 0; $i < $size; $i++) { 22 * $plaintext.= 'a'; 23 * } 24 * 25 * echo $des->decrypt($des->encrypt($plaintext)); 26 * ?> 27 * </code> 28 * 29 * @category Crypt 30 * @package TripleDES 31 * @author Jim Wigginton <terrafrost@php.net> 32 * @copyright 2007 Jim Wigginton 33 * @license http://www.opensource.org/licenses/mit-license.html MIT License 34 * @link http://phpseclib.sourceforge.net 35 */ 36 37 namespace phpseclib\Crypt; 38 39 /** 40 * Pure-PHP implementation of Triple DES. 41 * 42 * @package TripleDES 43 * @author Jim Wigginton <terrafrost@php.net> 44 * @access public 45 */ 46 class TripleDES extends DES 47 { 48 /** 49 * Encrypt / decrypt using inner chaining 50 * 51 * Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (self::MODE_CBC3). 52 */ 53 const MODE_3CBC = -2; 54 55 /** 56 * Encrypt / decrypt using outer chaining 57 * 58 * Outer chaining is used by SSH-2 and when the mode is set to \phpseclib\Crypt\Base::MODE_CBC. 59 */ 60 const MODE_CBC3 = self::MODE_CBC; 61 62 /** 63 * Key Length (in bytes) 64 * 65 * @see \phpseclib\Crypt\TripleDES::setKeyLength() 66 * @var int 67 * @access private 68 */ 69 var $key_length = 24; 70 71 /** 72 * The default salt used by setPassword() 73 * 74 * @see \phpseclib\Crypt\Base::password_default_salt 75 * @see \phpseclib\Crypt\Base::setPassword() 76 * @var string 77 * @access private 78 */ 79 var $password_default_salt = 'phpseclib'; 80 81 /** 82 * The mcrypt specific name of the cipher 83 * 84 * @see \phpseclib\Crypt\DES::cipher_name_mcrypt 85 * @see \phpseclib\Crypt\Base::cipher_name_mcrypt 86 * @var string 87 * @access private 88 */ 89 var $cipher_name_mcrypt = 'tripledes'; 90 91 /** 92 * Optimizing value while CFB-encrypting 93 * 94 * @see \phpseclib\Crypt\Base::cfb_init_len 95 * @var int 96 * @access private 97 */ 98 var $cfb_init_len = 750; 99 100 /** 101 * max possible size of $key 102 * 103 * @see self::setKey() 104 * @see \phpseclib\Crypt\DES::setKey() 105 * @var string 106 * @access private 107 */ 108 var $key_length_max = 24; 109 110 /** 111 * Internal flag whether using self::MODE_3CBC or not 112 * 113 * @var bool 114 * @access private 115 */ 116 var $mode_3cbc; 117 118 /** 119 * The \phpseclib\Crypt\DES objects 120 * 121 * Used only if $mode_3cbc === true 122 * 123 * @var array 124 * @access private 125 */ 126 var $des; 127 128 /** 129 * Default Constructor. 130 * 131 * Determines whether or not the mcrypt extension should be used. 132 * 133 * $mode could be: 134 * 135 * - \phpseclib\Crypt\Base::MODE_ECB 136 * 137 * - \phpseclib\Crypt\Base::MODE_CBC 138 * 139 * - \phpseclib\Crypt\Base::MODE_CTR 140 * 141 * - \phpseclib\Crypt\Base::MODE_CFB 142 * 143 * - \phpseclib\Crypt\Base::MODE_OFB 144 * 145 * - \phpseclib\Crypt\TripleDES::MODE_3CBC 146 * 147 * If not explicitly set, \phpseclib\Crypt\Base::MODE_CBC will be used. 148 * 149 * @see \phpseclib\Crypt\DES::__construct() 150 * @see \phpseclib\Crypt\Base::__construct() 151 * @param int $mode 152 * @access public 153 */ 154 function __construct($mode = self::MODE_CBC) 155 { 156 switch ($mode) { 157 // In case of self::MODE_3CBC, we init as CRYPT_DES_MODE_CBC 158 // and additional flag us internally as 3CBC 159 case self::MODE_3CBC: 160 parent::__construct(self::MODE_CBC); 161 $this->mode_3cbc = true; 162 163 // This three $des'es will do the 3CBC work (if $key > 64bits) 164 $this->des = array( 165 new DES(self::MODE_CBC), 166 new DES(self::MODE_CBC), 167 new DES(self::MODE_CBC), 168 ); 169 170 // we're going to be doing the padding, ourselves, so disable it in the \phpseclib\Crypt\DES objects 171 $this->des[0]->disablePadding(); 172 $this->des[1]->disablePadding(); 173 $this->des[2]->disablePadding(); 174 break; 175 // If not 3CBC, we init as usual 176 default: 177 parent::__construct($mode); 178 } 179 } 180 181 /** 182 * Test for engine validity 183 * 184 * This is mainly just a wrapper to set things up for \phpseclib\Crypt\Base::isValidEngine() 185 * 186 * @see \phpseclib\Crypt\Base::__construct() 187 * @param int $engine 188 * @access public 189 * @return bool 190 */ 191 function isValidEngine($engine) 192 { 193 if ($engine == self::ENGINE_OPENSSL) { 194 $this->cipher_name_openssl_ecb = 'des-ede3'; 195 $mode = $this->_openssl_translate_mode(); 196 $this->cipher_name_openssl = $mode == 'ecb' ? 'des-ede3' : 'des-ede3-' . $mode; 197 } 198 199 return parent::isValidEngine($engine); 200 } 201 202 /** 203 * Sets the initialization vector. (optional) 204 * 205 * SetIV is not required when \phpseclib\Crypt\Base::MODE_ECB is being used. If not explicitly set, it'll be assumed 206 * to be all zero's. 207 * 208 * @see \phpseclib\Crypt\Base::setIV() 209 * @access public 210 * @param string $iv 211 */ 212 function setIV($iv) 213 { 214 parent::setIV($iv); 215 if ($this->mode_3cbc) { 216 $this->des[0]->setIV($iv); 217 $this->des[1]->setIV($iv); 218 $this->des[2]->setIV($iv); 219 } 220 } 221 222 /** 223 * Sets the key length. 224 * 225 * Valid key lengths are 64, 128 and 192 226 * 227 * @see \phpseclib\Crypt\Base:setKeyLength() 228 * @access public 229 * @param int $length 230 */ 231 function setKeyLength($length) 232 { 233 $length >>= 3; 234 switch (true) { 235 case $length <= 8: 236 $this->key_length = 8; 237 break; 238 case $length <= 16: 239 $this->key_length = 16; 240 break; 241 default: 242 $this->key_length = 24; 243 } 244 245 parent::setKeyLength($length); 246 } 247 248 /** 249 * Sets the key. 250 * 251 * Keys can be of any length. Triple DES, itself, can use 128-bit (eg. strlen($key) == 16) or 252 * 192-bit (eg. strlen($key) == 24) keys. This function pads and truncates $key as appropriate. 253 * 254 * DES also requires that every eighth bit be a parity bit, however, we'll ignore that. 255 * 256 * If the key is not explicitly set, it'll be assumed to be all null bytes. 257 * 258 * @access public 259 * @see \phpseclib\Crypt\DES::setKey() 260 * @see \phpseclib\Crypt\Base::setKey() 261 * @param string $key 262 */ 263 function setKey($key) 264 { 265 $length = $this->explicit_key_length ? $this->key_length : strlen($key); 266 if ($length > 8) { 267 $key = str_pad(substr($key, 0, 24), 24, chr(0)); 268 // if $key is between 64 and 128-bits, use the first 64-bits as the last, per this: 269 // http://php.net/function.mcrypt-encrypt#47973 270 $key = $length <= 16 ? substr_replace($key, substr($key, 0, 8), 16) : substr($key, 0, 24); 271 } else { 272 $key = str_pad($key, 8, chr(0)); 273 } 274 parent::setKey($key); 275 276 // And in case of self::MODE_3CBC: 277 // if key <= 64bits we not need the 3 $des to work, 278 // because we will then act as regular DES-CBC with just a <= 64bit key. 279 // So only if the key > 64bits (> 8 bytes) we will call setKey() for the 3 $des. 280 if ($this->mode_3cbc && $length > 8) { 281 $this->des[0]->setKey(substr($key, 0, 8)); 282 $this->des[1]->setKey(substr($key, 8, 8)); 283 $this->des[2]->setKey(substr($key, 16, 8)); 284 } 285 } 286 287 /** 288 * Encrypts a message. 289 * 290 * @see \phpseclib\Crypt\Base::encrypt() 291 * @access public 292 * @param string $plaintext 293 * @return string $cipertext 294 */ 295 function encrypt($plaintext) 296 { 297 // parent::en/decrypt() is able to do all the work for all modes and keylengths, 298 // except for: self::MODE_3CBC (inner chaining CBC) with a key > 64bits 299 300 // if the key is smaller then 8, do what we'd normally do 301 if ($this->mode_3cbc && strlen($this->key) > 8) { 302 return $this->des[2]->encrypt( 303 $this->des[1]->decrypt( 304 $this->des[0]->encrypt( 305 $this->_pad($plaintext) 306 ) 307 ) 308 ); 309 } 310 311 return parent::encrypt($plaintext); 312 } 313 314 /** 315 * Decrypts a message. 316 * 317 * @see \phpseclib\Crypt\Base::decrypt() 318 * @access public 319 * @param string $ciphertext 320 * @return string $plaintext 321 */ 322 function decrypt($ciphertext) 323 { 324 if ($this->mode_3cbc && strlen($this->key) > 8) { 325 return $this->_unpad( 326 $this->des[0]->decrypt( 327 $this->des[1]->encrypt( 328 $this->des[2]->decrypt( 329 str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, "\0") 330 ) 331 ) 332 ) 333 ); 334 } 335 336 return parent::decrypt($ciphertext); 337 } 338 339 /** 340 * Treat consecutive "packets" as if they are a continuous buffer. 341 * 342 * Say you have a 16-byte plaintext $plaintext. Using the default behavior, the two following code snippets 343 * will yield different outputs: 344 * 345 * <code> 346 * echo $des->encrypt(substr($plaintext, 0, 8)); 347 * echo $des->encrypt(substr($plaintext, 8, 8)); 348 * </code> 349 * <code> 350 * echo $des->encrypt($plaintext); 351 * </code> 352 * 353 * The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates 354 * another, as demonstrated with the following: 355 * 356 * <code> 357 * $des->encrypt(substr($plaintext, 0, 8)); 358 * echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8))); 359 * </code> 360 * <code> 361 * echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8))); 362 * </code> 363 * 364 * With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different 365 * outputs. The reason is due to the fact that the initialization vector's change after every encryption / 366 * decryption round when the continuous buffer is enabled. When it's disabled, they remain constant. 367 * 368 * Put another way, when the continuous buffer is enabled, the state of the \phpseclib\Crypt\DES() object changes after each 369 * encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that 370 * continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them), 371 * however, they are also less intuitive and more likely to cause you problems. 372 * 373 * @see \phpseclib\Crypt\Base::enableContinuousBuffer() 374 * @see self::disableContinuousBuffer() 375 * @access public 376 */ 377 function enableContinuousBuffer() 378 { 379 parent::enableContinuousBuffer(); 380 if ($this->mode_3cbc) { 381 $this->des[0]->enableContinuousBuffer(); 382 $this->des[1]->enableContinuousBuffer(); 383 $this->des[2]->enableContinuousBuffer(); 384 } 385 } 386 387 /** 388 * Treat consecutive packets as if they are a discontinuous buffer. 389 * 390 * The default behavior. 391 * 392 * @see \phpseclib\Crypt\Base::disableContinuousBuffer() 393 * @see self::enableContinuousBuffer() 394 * @access public 395 */ 396 function disableContinuousBuffer() 397 { 398 parent::disableContinuousBuffer(); 399 if ($this->mode_3cbc) { 400 $this->des[0]->disableContinuousBuffer(); 401 $this->des[1]->disableContinuousBuffer(); 402 $this->des[2]->disableContinuousBuffer(); 403 } 404 } 405 406 /** 407 * Creates the key schedule 408 * 409 * @see \phpseclib\Crypt\DES::_setupKey() 410 * @see \phpseclib\Crypt\Base::_setupKey() 411 * @access private 412 */ 413 function _setupKey() 414 { 415 switch (true) { 416 // if $key <= 64bits we configure our internal pure-php cipher engine 417 // to act as regular [1]DES, not as 3DES. mcrypt.so::tripledes does the same. 418 case strlen($this->key) <= 8: 419 $this->des_rounds = 1; 420 break; 421 422 // otherwise, if $key > 64bits, we configure our engine to work as 3DES. 423 default: 424 $this->des_rounds = 3; 425 426 // (only) if 3CBC is used we have, of course, to setup the $des[0-2] keys also separately. 427 if ($this->mode_3cbc) { 428 $this->des[0]->_setupKey(); 429 $this->des[1]->_setupKey(); 430 $this->des[2]->_setupKey(); 431 432 // because $des[0-2] will, now, do all the work we can return here 433 // not need unnecessary stress parent::_setupKey() with our, now unused, $key. 434 return; 435 } 436 } 437 // setup our key 438 parent::_setupKey(); 439 } 440 441 /** 442 * Sets the internal crypt engine 443 * 444 * @see \phpseclib\Crypt\Base::__construct() 445 * @see \phpseclib\Crypt\Base::setPreferredEngine() 446 * @param int $engine 447 * @access public 448 * @return int 449 */ 450 function setPreferredEngine($engine) 451 { 452 if ($this->mode_3cbc) { 453 $this->des[0]->setPreferredEngine($engine); 454 $this->des[1]->setPreferredEngine($engine); 455 $this->des[2]->setPreferredEngine($engine); 456 } 457 458 return parent::setPreferredEngine($engine); 459 } 460 }
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