[Summary view] [Print] [Text view]

   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  }