[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 \phpseclib3\Crypt\TripleDES('ctr');
  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 <[email protected]>
  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 phpseclib3\Crypt;
  38  
  39  /**
  40   * Pure-PHP implementation of Triple DES.
  41   *
  42   * @package TripleDES
  43   * @author  Jim Wigginton <[email protected]>
  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 \phpseclib3\Crypt\Common\BlockCipher::MODE_CBC.
  59       */
  60      const MODE_CBC3 = self::MODE_CBC;
  61  
  62      /**
  63       * Key Length (in bytes)
  64       *
  65       * @see \phpseclib3\Crypt\TripleDES::setKeyLength()
  66       * @var int
  67       * @access private
  68       */
  69      protected $key_length = 24;
  70  
  71      /**
  72       * The mcrypt specific name of the cipher
  73       *
  74       * @see \phpseclib3\Crypt\DES::cipher_name_mcrypt
  75       * @see \phpseclib3\Crypt\Common\SymmetricKey::cipher_name_mcrypt
  76       * @var string
  77       * @access private
  78       */
  79      protected $cipher_name_mcrypt = 'tripledes';
  80  
  81      /**
  82       * Optimizing value while CFB-encrypting
  83       *
  84       * @see \phpseclib3\Crypt\Common\SymmetricKey::cfb_init_len
  85       * @var int
  86       * @access private
  87       */
  88      protected $cfb_init_len = 750;
  89  
  90      /**
  91       * max possible size of $key
  92       *
  93       * @see self::setKey()
  94       * @see \phpseclib3\Crypt\DES::setKey()
  95       * @var string
  96       * @access private
  97       */
  98      protected $key_length_max = 24;
  99  
 100      /**
 101       * Internal flag whether using self::MODE_3CBC or not
 102       *
 103       * @var bool
 104       * @access private
 105       */
 106      private $mode_3cbc;
 107  
 108      /**
 109       * The \phpseclib3\Crypt\DES objects
 110       *
 111       * Used only if $mode_3cbc === true
 112       *
 113       * @var array
 114       * @access private
 115       */
 116      private $des;
 117  
 118      /**
 119       * Default Constructor.
 120       *
 121       * Determines whether or not the mcrypt or OpenSSL extensions should be used.
 122       *
 123       * $mode could be:
 124       *
 125       * - ecb
 126       *
 127       * - cbc
 128       *
 129       * - ctr
 130       *
 131       * - cfb
 132       *
 133       * - ofb
 134       *
 135       * - 3cbc
 136       *
 137       * - cbc3 (same as cbc)
 138       *
 139       * @see \phpseclib3\Crypt\DES::__construct()
 140       * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct()
 141       * @param string $mode
 142       * @access public
 143       */
 144      public function __construct($mode)
 145      {
 146          switch (strtolower($mode)) {
 147              // In case of self::MODE_3CBC, we init as CRYPT_DES_MODE_CBC
 148              // and additional flag us internally as 3CBC
 149              case '3cbc':
 150                  parent::__construct('cbc');
 151                  $this->mode_3cbc = true;
 152  
 153                  // This three $des'es will do the 3CBC work (if $key > 64bits)
 154                  $this->des = [
 155                      new DES('cbc'),
 156                      new DES('cbc'),
 157                      new DES('cbc'),
 158                  ];
 159  
 160                  // we're going to be doing the padding, ourselves, so disable it in the \phpseclib3\Crypt\DES objects
 161                  $this->des[0]->disablePadding();
 162                  $this->des[1]->disablePadding();
 163                  $this->des[2]->disablePadding();
 164                  break;
 165              case 'cbc3':
 166                  $mode = 'cbc';
 167                  // fall-through
 168              // If not 3CBC, we init as usual
 169              default:
 170                  parent::__construct($mode);
 171  
 172                  if ($this->mode == self::MODE_STREAM) {
 173                      throw new BadModeException('Block ciphers cannot be ran in stream mode');
 174                  }
 175          }
 176      }
 177  
 178      /**
 179       * Test for engine validity
 180       *
 181       * This is mainly just a wrapper to set things up for \phpseclib3\Crypt\Common\SymmetricKey::isValidEngine()
 182       *
 183       * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct()
 184       * @param int $engine
 185       * @access protected
 186       * @return bool
 187       */
 188      protected function isValidEngineHelper($engine)
 189      {
 190          if ($engine == self::ENGINE_OPENSSL) {
 191              $this->cipher_name_openssl_ecb = 'des-ede3';
 192              $mode = $this->openssl_translate_mode();
 193              $this->cipher_name_openssl = $mode == 'ecb' ? 'des-ede3' : 'des-ede3-' . $mode;
 194          }
 195  
 196          return parent::isValidEngineHelper($engine);
 197      }
 198  
 199      /**
 200       * Sets the initialization vector.
 201       *
 202       * SetIV is not required when \phpseclib3\Crypt\Common\SymmetricKey::MODE_ECB is being used.
 203       *
 204       * @see \phpseclib3\Crypt\Common\SymmetricKey::setIV()
 205       * @access public
 206       * @param string $iv
 207       */
 208      public function setIV($iv)
 209      {
 210          parent::setIV($iv);
 211          if ($this->mode_3cbc) {
 212              $this->des[0]->setIV($iv);
 213              $this->des[1]->setIV($iv);
 214              $this->des[2]->setIV($iv);
 215          }
 216      }
 217  
 218      /**
 219       * Sets the key length.
 220       *
 221       * Valid key lengths are 128 and 192 bits.
 222       *
 223       * If you want to use a 64-bit key use DES.php
 224       *
 225       * @see \phpseclib3\Crypt\Common\SymmetricKey:setKeyLength()
 226       * @access public
 227       * @throws \LengthException if the key length is invalid
 228       * @param int $length
 229       */
 230      public function setKeyLength($length)
 231      {
 232          switch ($length) {
 233              case 128:
 234              case 192:
 235                  break;
 236              default:
 237                  throw new \LengthException('Key size of ' . $length . ' bits is not supported by this algorithm. Only keys of sizes 128 or 192 bits are supported');
 238          }
 239  
 240          parent::setKeyLength($length);
 241      }
 242  
 243      /**
 244       * Sets the key.
 245       *
 246       * Triple DES can use 128-bit (eg. strlen($key) == 16) or 192-bit (eg. strlen($key) == 24) keys.
 247       *
 248       * DES also requires that every eighth bit be a parity bit, however, we'll ignore that.
 249       *
 250       * @access public
 251       * @see \phpseclib3\Crypt\DES::setKey()
 252       * @see \phpseclib3\Crypt\Common\SymmetricKey::setKey()
 253       * @throws \LengthException if the key length is invalid
 254       * @param string $key
 255       */
 256      public function setKey($key)
 257      {
 258          if ($this->explicit_key_length !== false && strlen($key) != $this->explicit_key_length) {
 259              throw new \LengthException('Key length has already been set to ' . $this->explicit_key_length . ' bytes and this key is ' . strlen($key) . ' bytes');
 260          }
 261  
 262          switch (strlen($key)) {
 263              case 16:
 264                  $key .= substr($key, 0, 8);
 265                  break;
 266              case 24:
 267                  break;
 268              default:
 269                  throw new \LengthException('Key of size ' . strlen($key) . ' not supported by this algorithm. Only keys of sizes 16 or 24 are supported');
 270          }
 271  
 272          // copied from self::setKey()
 273          $this->key = $key;
 274          $this->key_length = strlen($key);
 275          $this->changed = $this->nonIVChanged = true;
 276          $this->setEngine();
 277  
 278          if ($this->mode_3cbc) {
 279              $this->des[0]->setKey(substr($key, 0, 8));
 280              $this->des[1]->setKey(substr($key, 8, 8));
 281              $this->des[2]->setKey(substr($key, 16, 8));
 282          }
 283      }
 284  
 285      /**
 286       * Encrypts a message.
 287       *
 288       * @see \phpseclib3\Crypt\Common\SymmetricKey::encrypt()
 289       * @access public
 290       * @param string $plaintext
 291       * @return string $cipertext
 292       */
 293      public function encrypt($plaintext)
 294      {
 295          // parent::en/decrypt() is able to do all the work for all modes and keylengths,
 296          // except for: self::MODE_3CBC (inner chaining CBC) with a key > 64bits
 297  
 298          // if the key is smaller then 8, do what we'd normally do
 299          if ($this->mode_3cbc && strlen($this->key) > 8) {
 300              return $this->des[2]->encrypt(
 301                  $this->des[1]->decrypt(
 302                      $this->des[0]->encrypt(
 303                          $this->pad($plaintext)
 304                      )
 305                  )
 306              );
 307          }
 308  
 309          return parent::encrypt($plaintext);
 310      }
 311  
 312      /**
 313       * Decrypts a message.
 314       *
 315       * @see \phpseclib3\Crypt\Common\SymmetricKey::decrypt()
 316       * @access public
 317       * @param string $ciphertext
 318       * @return string $plaintext
 319       */
 320      public function decrypt($ciphertext)
 321      {
 322          if ($this->mode_3cbc && strlen($this->key) > 8) {
 323              return $this->unpad(
 324                  $this->des[0]->decrypt(
 325                      $this->des[1]->encrypt(
 326                          $this->des[2]->decrypt(
 327                              str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, "\0")
 328                          )
 329                      )
 330                  )
 331              );
 332          }
 333  
 334          return parent::decrypt($ciphertext);
 335      }
 336  
 337      /**
 338       * Treat consecutive "packets" as if they are a continuous buffer.
 339       *
 340       * Say you have a 16-byte plaintext $plaintext.  Using the default behavior, the two following code snippets
 341       * will yield different outputs:
 342       *
 343       * <code>
 344       *    echo $des->encrypt(substr($plaintext, 0, 8));
 345       *    echo $des->encrypt(substr($plaintext, 8, 8));
 346       * </code>
 347       * <code>
 348       *    echo $des->encrypt($plaintext);
 349       * </code>
 350       *
 351       * The solution is to enable the continuous buffer.  Although this will resolve the above discrepancy, it creates
 352       * another, as demonstrated with the following:
 353       *
 354       * <code>
 355       *    $des->encrypt(substr($plaintext, 0, 8));
 356       *    echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
 357       * </code>
 358       * <code>
 359       *    echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
 360       * </code>
 361       *
 362       * With the continuous buffer disabled, these would yield the same output.  With it enabled, they yield different
 363       * outputs.  The reason is due to the fact that the initialization vector's change after every encryption /
 364       * decryption round when the continuous buffer is enabled.  When it's disabled, they remain constant.
 365       *
 366       * Put another way, when the continuous buffer is enabled, the state of the \phpseclib3\Crypt\DES() object changes after each
 367       * encryption / decryption round, whereas otherwise, it'd remain constant.  For this reason, it's recommended that
 368       * continuous buffers not be used.  They do offer better security and are, in fact, sometimes required (SSH uses them),
 369       * however, they are also less intuitive and more likely to cause you problems.
 370       *
 371       * @see \phpseclib3\Crypt\Common\SymmetricKey::enableContinuousBuffer()
 372       * @see self::disableContinuousBuffer()
 373       * @access public
 374       */
 375      public function enableContinuousBuffer()
 376      {
 377          parent::enableContinuousBuffer();
 378          if ($this->mode_3cbc) {
 379              $this->des[0]->enableContinuousBuffer();
 380              $this->des[1]->enableContinuousBuffer();
 381              $this->des[2]->enableContinuousBuffer();
 382          }
 383      }
 384  
 385      /**
 386       * Treat consecutive packets as if they are a discontinuous buffer.
 387       *
 388       * The default behavior.
 389       *
 390       * @see \phpseclib3\Crypt\Common\SymmetricKey::disableContinuousBuffer()
 391       * @see self::enableContinuousBuffer()
 392       * @access public
 393       */
 394      public function disableContinuousBuffer()
 395      {
 396          parent::disableContinuousBuffer();
 397          if ($this->mode_3cbc) {
 398              $this->des[0]->disableContinuousBuffer();
 399              $this->des[1]->disableContinuousBuffer();
 400              $this->des[2]->disableContinuousBuffer();
 401          }
 402      }
 403  
 404      /**
 405       * Creates the key schedule
 406       *
 407       * @see \phpseclib3\Crypt\DES::setupKey()
 408       * @see \phpseclib3\Crypt\Common\SymmetricKey::setupKey()
 409       * @access private
 410       */
 411      protected function setupKey()
 412      {
 413          switch (true) {
 414              // if $key <= 64bits we configure our internal pure-php cipher engine
 415              // to act as regular [1]DES, not as 3DES. mcrypt.so::tripledes does the same.
 416              case strlen($this->key) <= 8:
 417                  $this->des_rounds = 1;
 418                  break;
 419  
 420              // otherwise, if $key > 64bits, we configure our engine to work as 3DES.
 421              default:
 422                  $this->des_rounds = 3;
 423  
 424                  // (only) if 3CBC is used we have, of course, to setup the $des[0-2] keys also separately.
 425                  if ($this->mode_3cbc) {
 426                      $this->des[0]->setupKey();
 427                      $this->des[1]->setupKey();
 428                      $this->des[2]->setupKey();
 429  
 430                      // because $des[0-2] will, now, do all the work we can return here
 431                      // not need unnecessary stress parent::setupKey() with our, now unused, $key.
 432                      return;
 433                  }
 434          }
 435          // setup our key
 436          parent::setupKey();
 437      }
 438  
 439      /**
 440       * Sets the internal crypt engine
 441       *
 442       * @see \phpseclib3\Crypt\Common\SymmetricKey::__construct()
 443       * @see \phpseclib3\Crypt\Common\SymmetricKey::setPreferredEngine()
 444       * @param int $engine
 445       * @access public
 446       */
 447      public function setPreferredEngine($engine)
 448      {
 449          if ($this->mode_3cbc) {
 450              $this->des[0]->setPreferredEngine($engine);
 451              $this->des[1]->setPreferredEngine($engine);
 452              $this->des[2]->setPreferredEngine($engine);
 453          }
 454  
 455          parent::setPreferredEngine($engine);
 456      }
 457  }