Ejemplo n.º 1
0
 /**
  * Treat consecutive "packets" as if they are a continuous buffer.
  *
  * Say you have a 16-byte plaintext $plaintext.  Using the default behavior, the two following code snippets
  * will yield different outputs:
  *
  * <code>
  *    echo $des->encrypt(substr($plaintext, 0, 8));
  *    echo $des->encrypt(substr($plaintext, 8, 8));
  * </code>
  * <code>
  *    echo $des->encrypt($plaintext);
  * </code>
  *
  * The solution is to enable the continuous buffer.  Although this will resolve the above discrepancy, it creates
  * another, as demonstrated with the following:
  *
  * <code>
  *    $des->encrypt(substr($plaintext, 0, 8));
  *    echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
  * </code>
  * <code>
  *    echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8)));
  * </code>
  *
  * With the continuous buffer disabled, these would yield the same output.  With it enabled, they yield different
  * outputs.  The reason is due to the fact that the initialization vector's change after every encryption /
  * decryption round when the continuous buffer is enabled.  When it's disabled, they remain constant.
  *
  * Put another way, when the continuous buffer is enabled, the state of the Crypt_DES() object changes after each
  * encryption / decryption round, whereas otherwise, it'd remain constant.  For this reason, it's recommended that
  * continuous buffers not be used.  They do offer better security and are, in fact, sometimes required (SSH uses them),
  * however, they are also less intuitive and more likely to cause you problems.
  *
  * @see Crypt_Base::enableContinuousBuffer()
  * @see Crypt_TripleDES::disableContinuousBuffer()
  * @access public
  */
 function enableContinuousBuffer()
 {
     parent::enableContinuousBuffer();
     if ($this->mode_3cbc) {
         $this->des[0]->enableContinuousBuffer();
         $this->des[1]->enableContinuousBuffer();
         $this->des[2]->enableContinuousBuffer();
     }
 }