* setKey('abcdefghijklmnopqrstuvwx'); * * $size = 10 * 1024; * $plaintext = ''; * for ($i = 0; $i < $size; $i++) { * $plaintext.= 'a'; * } * * echo $des->decrypt($des->encrypt($plaintext)); * ?> * * * LICENSE: Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. * * @category Crypt * @package Crypt_TripleDES * @author Jim Wigginton * @copyright MMVII Jim Wigginton * @license http://www.opensource.org/licenses/mit-license.html MIT License * @version $Id$ * @link http://phpseclib.sourceforge.net */ /** * Include Crypt_DES */ require_once('DES.php'); /** * Encrypt / decrypt using inner chaining * * Inner chaining is used by SSH-1 and is generally considered to be less secure then outer chaining (CRYPT_DES_MODE_CBC3). */ define('CRYPT_DES_MODE_3CBC', -2); /** * Encrypt / decrypt using outer chaining * * Outer chaining is used by SSH-2 and when the mode is set to CRYPT_DES_MODE_CBC. */ define('CRYPT_DES_MODE_CBC3', CRYPT_DES_MODE_CBC); /** * Pure-PHP implementation of Triple DES. * * @author Jim Wigginton * @version 0.1.0 * @access public * @package Crypt_TerraDES */ class Crypt_TripleDES { /** * The Three Keys * * @see Crypt_TripleDES::setKey() * @var String * @access private */ var $key = "\0\0\0\0\0\0\0\0"; /** * The Encryption Mode * * @see Crypt_TripleDES::Crypt_TripleDES() * @var Integer * @access private */ var $mode = CRYPT_DES_MODE_CBC; /** * Continuous Buffer status * * @see Crypt_TripleDES::enableContinuousBuffer() * @var Boolean * @access private */ var $continuousBuffer = false; /** * Padding status * * @see Crypt_TripleDES::enablePadding() * @var Boolean * @access private */ var $padding = true; /** * The Initialization Vector * * @see Crypt_TripleDES::setIV() * @var String * @access private */ var $iv = "\0\0\0\0\0\0\0\0"; /** * A "sliding" Initialization Vector * * @see Crypt_TripleDES::enableContinuousBuffer() * @var String * @access private */ var $encryptIV = "\0\0\0\0\0\0\0\0"; /** * A "sliding" Initialization Vector * * @see Crypt_TripleDES::enableContinuousBuffer() * @var String * @access private */ var $decryptIV = "\0\0\0\0\0\0\0\0"; /** * The Crypt_DES objects * * @var Array * @access private */ var $des; /** * mcrypt resource for encryption * * The mcrypt resource can be recreated every time something needs to be created or it can be created just once. * Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode. * * @see Crypt_TripleDES::encrypt() * @var String * @access private */ var $enmcrypt; /** * mcrypt resource for decryption * * The mcrypt resource can be recreated every time something needs to be created or it can be created just once. * Since mcrypt operates in continuous mode, by default, it'll need to be recreated when in non-continuous mode. * * @see Crypt_TripleDES::decrypt() * @var String * @access private */ var $demcrypt; /** * Does the enmcrypt resource need to be (re)initialized? * * @see Crypt_TripleDES::setKey() * @see Crypt_TripleDES::setIV() * @var Boolean * @access private */ var $enchanged = true; /** * Does the demcrypt resource need to be (re)initialized? * * @see Crypt_TripleDES::setKey() * @see Crypt_TripleDES::setIV() * @var Boolean * @access private */ var $dechanged = true; /** * Is the mode one that is paddable? * * @see Crypt_TripleDES::Crypt_TripleDES() * @var Boolean * @access private */ var $paddable = false; /** * Encryption buffer for CTR, OFB and CFB modes * * @see Crypt_TripleDES::encrypt() * @var String * @access private */ var $enbuffer = ''; /** * Decryption buffer for CTR, OFB and CFB modes * * @see Crypt_TripleDES::decrypt() * @var String * @access private */ var $debuffer = ''; /** * mcrypt resource for CFB mode * * @see Crypt_TripleDES::encrypt() * @see Crypt_TripleDES::decrypt() * @var String * @access private */ var $ecb; /** * Default Constructor. * * Determines whether or not the mcrypt extension should be used. $mode should only, at present, be * CRYPT_DES_MODE_ECB or CRYPT_DES_MODE_CBC. If not explictly set, CRYPT_DES_MODE_CBC will be used. * * @param optional Integer $mode * @return Crypt_TripleDES * @access public */ function Crypt_TripleDES($mode = CRYPT_DES_MODE_CBC) { if ( !defined('CRYPT_DES_MODE') ) { switch (true) { case extension_loaded('mcrypt'): // i'd check to see if des was supported, by doing in_array('des', mcrypt_list_algorithms('')), // but since that can be changed after the object has been created, there doesn't seem to be // a lot of point... define('CRYPT_DES_MODE', CRYPT_DES_MODE_MCRYPT); break; default: define('CRYPT_DES_MODE', CRYPT_DES_MODE_INTERNAL); } } if ( $mode == CRYPT_DES_MODE_3CBC ) { $this->mode = CRYPT_DES_MODE_3CBC; $this->des = array( new Crypt_DES(CRYPT_DES_MODE_CBC), new Crypt_DES(CRYPT_DES_MODE_CBC), new Crypt_DES(CRYPT_DES_MODE_CBC) ); // we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects $this->des[0]->disablePadding(); $this->des[1]->disablePadding(); $this->des[2]->disablePadding(); return; } switch ( CRYPT_DES_MODE ) { case CRYPT_DES_MODE_MCRYPT: switch ($mode) { case CRYPT_DES_MODE_ECB: $this->paddable = true; $this->mode = MCRYPT_MODE_ECB; break; case CRYPT_DES_MODE_CTR: $this->mode = 'ctr'; break; case CRYPT_DES_MODE_CFB: $this->mode = 'ncfb'; break; case CRYPT_DES_MODE_OFB: $this->mode = MCRYPT_MODE_NOFB; break; case CRYPT_DES_MODE_CBC: default: $this->paddable = true; $this->mode = MCRYPT_MODE_CBC; } break; default: $this->des = array( new Crypt_DES(CRYPT_DES_MODE_ECB), new Crypt_DES(CRYPT_DES_MODE_ECB), new Crypt_DES(CRYPT_DES_MODE_ECB) ); // we're going to be doing the padding, ourselves, so disable it in the Crypt_DES objects $this->des[0]->disablePadding(); $this->des[1]->disablePadding(); $this->des[2]->disablePadding(); switch ($mode) { case CRYPT_DES_MODE_ECB: case CRYPT_DES_MODE_CBC: $this->paddable = true; $this->mode = $mode; break; case CRYPT_DES_MODE_CTR: case CRYPT_DES_MODE_CFB: case CRYPT_DES_MODE_OFB: $this->mode = $mode; break; default: $this->paddable = true; $this->mode = CRYPT_DES_MODE_CBC; } } } /** * Sets the key. * * Keys can be of any length. Triple DES, itself, can use 128-bit (eg. strlen($key) == 16) or * 192-bit (eg. strlen($key) == 24) keys. This function pads and truncates $key as appropriate. * * DES also requires that every eighth bit be a parity bit, however, we'll ignore that. * * If the key is not explicitly set, it'll be assumed to be all zero's. * * @access public * @param String $key */ function setKey($key) { $length = strlen($key); if ($length > 8) { $key = str_pad($key, 24, chr(0)); // if $key is between 64 and 128-bits, use the first 64-bits as the last, per this: // http://php.net/function.mcrypt-encrypt#47973 //$key = $length <= 16 ? substr_replace($key, substr($key, 0, 8), 16) : substr($key, 0, 24); } else { $key = str_pad($key, 8, chr(0)); } $this->key = $key; switch (true) { case CRYPT_DES_MODE == CRYPT_DES_MODE_INTERNAL: case $this->mode == CRYPT_DES_MODE_3CBC: $this->des[0]->setKey(substr($key, 0, 8)); $this->des[1]->setKey(substr($key, 8, 8)); $this->des[2]->setKey(substr($key, 16, 8)); } $this->enchanged = $this->dechanged = true; } /** * Sets the initialization vector. (optional) * * SetIV is not required when CRYPT_DES_MODE_ECB is being used. If not explictly set, it'll be assumed * to be all zero's. * * @access public * @param String $iv */ function setIV($iv) { $this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($iv, 0, 8), 8, chr(0)); if ($this->mode == CRYPT_DES_MODE_3CBC) { $this->des[0]->setIV($iv); $this->des[1]->setIV($iv); $this->des[2]->setIV($iv); } $this->enchanged = $this->dechanged = true; } /** * Generate CTR XOR encryption key * * Encrypt the output of this and XOR it against the ciphertext / plaintext to get the * plaintext / ciphertext in CTR mode. * * @see Crypt_TripleDES::decrypt() * @see Crypt_TripleDES::encrypt() * @access private * @param Integer $length * @param String $iv */ function _generate_xor($length, &$iv) { $xor = ''; $num_blocks = ($length + 7) >> 3; for ($i = 0; $i < $num_blocks; $i++) { $xor.= $iv; for ($j = 4; $j <= 8; $j+=4) { $temp = substr($iv, -$j, 4); switch ($temp) { case "\xFF\xFF\xFF\xFF": $iv = substr_replace($iv, "\x00\x00\x00\x00", -$j, 4); break; case "\x7F\xFF\xFF\xFF": $iv = substr_replace($iv, "\x80\x00\x00\x00", -$j, 4); break 2; default: extract(unpack('Ncount', $temp)); $iv = substr_replace($iv, pack('N', $count + 1), -$j, 4); break 2; } } } return $xor; } /** * Encrypts a message. * * @access public * @param String $plaintext */ function encrypt($plaintext) { if ($this->paddable) { $plaintext = $this->_pad($plaintext); } // if the key is smaller then 8, do what we'd normally do if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) { $ciphertext = $this->des[2]->encrypt($this->des[1]->decrypt($this->des[0]->encrypt($plaintext))); return $ciphertext; } if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) { if ($this->enchanged) { if (!isset($this->enmcrypt)) { $this->enmcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, ''); } mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV); if ($this->mode != 'ncfb') { $this->enchanged = false; } } if ($this->mode != 'ncfb') { $ciphertext = mcrypt_generic($this->enmcrypt, $plaintext); } else { if ($this->enchanged) { $this->ecb = mcrypt_module_open(MCRYPT_3DES, '', MCRYPT_MODE_ECB, ''); mcrypt_generic_init($this->ecb, $this->key, "\0\0\0\0\0\0\0\0"); $this->enchanged = false; } if (strlen($this->enbuffer)) { $ciphertext = $plaintext ^ substr($this->encryptIV, strlen($this->enbuffer)); $this->enbuffer.= $ciphertext; if (strlen($this->enbuffer) == 8) { $this->encryptIV = $this->enbuffer; $this->enbuffer = ''; mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV); } $plaintext = substr($plaintext, strlen($ciphertext)); } else { $ciphertext = ''; } $last_pos = strlen($plaintext) & 0xFFFFFFF8; $ciphertext.= $last_pos ? mcrypt_generic($this->enmcrypt, substr($plaintext, 0, $last_pos)) : ''; if (strlen($plaintext) & 0x7) { if (strlen($ciphertext)) { $this->encryptIV = substr($ciphertext, -8); } $this->encryptIV = mcrypt_generic($this->ecb, $this->encryptIV); $this->enbuffer = substr($plaintext, $last_pos) ^ $this->encryptIV; $ciphertext.= $this->enbuffer; } } if (!$this->continuousBuffer) { mcrypt_generic_init($this->enmcrypt, $this->key, $this->encryptIV); } return $ciphertext; } if (strlen($this->key) <= 8) { $this->des[0]->mode = $this->mode; return $this->des[0]->encrypt($plaintext); } $des = $this->des; $buffer = &$this->enbuffer; $continuousBuffer = $this->continuousBuffer; $ciphertext = ''; switch ($this->mode) { case CRYPT_DES_MODE_ECB: for ($i = 0; $i < strlen($plaintext); $i+=8) { $block = substr($plaintext, $i, 8); // all of these _processBlock calls could, in theory, be put in a function - say Crypt_TripleDES::_ede_encrypt() or something. // only problem with that: it would slow encryption and decryption down. $this->des would have to be called every time that // function is called, instead of once for the whole string of text that's being encrypted, which would, in turn, make // encryption and decryption take more time, per this: // // http://blog.libssh2.org/index.php?/archives/21-Compiled-Variables.html $block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT); $block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT); $block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT); $ciphertext.= $block; } break; case CRYPT_DES_MODE_CBC: $xor = $this->encryptIV; for ($i = 0; $i < strlen($plaintext); $i+=8) { $block = substr($plaintext, $i, 8) ^ $xor; $block = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT); $block = $des[1]->_processBlock($block, CRYPT_DES_DECRYPT); $block = $des[2]->_processBlock($block, CRYPT_DES_ENCRYPT); $xor = $block; $ciphertext.= $block; } if ($this->continuousBuffer) { $this->encryptIV = $xor; } break; case CRYPT_DES_MODE_CTR: $xor = $this->encryptIV; if (strlen($buffer)) { for ($i = 0; $i < strlen($plaintext); $i+=8) { $block = substr($plaintext, $i, 8); $key = $this->_generate_xor(8, $xor); $key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT); $key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT); $key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT); $buffer.= $key; $key = $this->_string_shift($buffer, 8); $ciphertext.= $block ^ $key; } } else { for ($i = 0; $i < strlen($plaintext); $i+=8) { $block = substr($plaintext, $i, 8); $key = $this->_generate_xor(8, $xor); $key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT); $key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT); $key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT); $ciphertext.= $block ^ $key; } } if ($this->continuousBuffer) { $this->encryptIV = $xor; if ($start = strlen($plaintext) & 7) { $buffer = substr($key, $start) . $buffer; } } break; case CRYPT_DES_MODE_CFB: if (!empty($buffer['xor'])) { $ciphertext = $plaintext ^ $buffer['xor']; $iv = $buffer['encrypted'] . $ciphertext; $start = strlen($ciphertext); $buffer['encrypted'].= $ciphertext; $buffer['xor'] = substr($buffer['xor'], strlen($ciphertext)); } else { $ciphertext = ''; $iv = $this->encryptIV; $start = 0; } for ($i = $start; $i < strlen($plaintext); $i+=8) { $block = substr($plaintext, $i, 8); $iv = $des[0]->_processBlock($iv, CRYPT_DES_ENCRYPT); $iv = $des[1]->_processBlock($iv, CRYPT_DES_DECRYPT); $xor= $des[2]->_processBlock($iv, CRYPT_DES_ENCRYPT); $iv = $block ^ $xor; if ($continuousBuffer && strlen($iv) != 8) { $buffer = array( 'encrypted' => $iv, 'xor' => substr($xor, strlen($iv)) ); } $ciphertext.= $iv; } if ($this->continuousBuffer) { $this->encryptIV = $iv; } break; case CRYPT_DES_MODE_OFB: $xor = $this->encryptIV; if (strlen($buffer)) { for ($i = 0; $i < strlen($plaintext); $i+=8) { $xor = $des[0]->_processBlock($xor, CRYPT_DES_ENCRYPT); $xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT); $xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT); $buffer.= $xor; $key = $this->_string_shift($buffer, 8); $ciphertext.= substr($plaintext, $i, 8) ^ $key; } } else { for ($i = 0; $i < strlen($plaintext); $i+=8) { $xor = $des[0]->_processBlock($xor, CRYPT_DES_ENCRYPT); $xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT); $xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT); $ciphertext.= substr($plaintext, $i, 8) ^ $xor; } $key = $xor; } if ($this->continuousBuffer) { $this->encryptIV = $xor; if ($start = strlen($plaintext) & 7) { $buffer = substr($key, $start) . $buffer; } } } return $ciphertext; } /** * Decrypts a message. * * @access public * @param String $ciphertext */ function decrypt($ciphertext) { if ($this->mode == CRYPT_DES_MODE_3CBC && strlen($this->key) > 8) { $plaintext = $this->des[0]->decrypt($this->des[1]->encrypt($this->des[2]->decrypt($ciphertext))); return $this->_unpad($plaintext); } if ($this->paddable) { // we pad with chr(0) since that's what mcrypt_generic does. to quote from http://php.net/function.mcrypt-generic : // "The data is padded with "\0" to make sure the length of the data is n * blocksize." $ciphertext = str_pad($ciphertext, (strlen($ciphertext) + 7) & 0xFFFFFFF8, chr(0)); } if ( CRYPT_DES_MODE == CRYPT_DES_MODE_MCRYPT ) { if ($this->dechanged) { if (!isset($this->demcrypt)) { $this->demcrypt = mcrypt_module_open(MCRYPT_3DES, '', $this->mode, ''); } mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV); if ($this->mode != 'ncfb') { $this->dechanged = false; } } if ($this->mode != 'ncfb') { $plaintext = mdecrypt_generic($this->demcrypt, $ciphertext); } else { if ($this->dechanged) { $this->ecb = mcrypt_module_open(MCRYPT_3DES, '', MCRYPT_MODE_ECB, ''); mcrypt_generic_init($this->ecb, $this->key, "\0\0\0\0\0\0\0\0"); $this->dechanged = false; } if (strlen($this->debuffer)) { $plaintext = $ciphertext ^ substr($this->decryptIV, strlen($this->debuffer)); $this->debuffer.= substr($ciphertext, 0, strlen($plaintext)); if (strlen($this->debuffer) == 8) { $this->decryptIV = $this->debuffer; $this->debuffer = ''; mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV); } $ciphertext = substr($ciphertext, strlen($plaintext)); } else { $plaintext = ''; } $last_pos = strlen($ciphertext) & 0xFFFFFFF8; $plaintext.= $last_pos ? mdecrypt_generic($this->demcrypt, substr($ciphertext, 0, $last_pos)) : ''; if (strlen($ciphertext) & 0x7) { if (strlen($plaintext)) { $this->decryptIV = substr($ciphertext, $last_pos - 8, 8); } $this->decryptIV = mcrypt_generic($this->ecb, $this->decryptIV); $this->debuffer = substr($ciphertext, $last_pos); $plaintext.= $this->debuffer ^ $this->decryptIV; } return $plaintext; } if (!$this->continuousBuffer) { mcrypt_generic_init($this->demcrypt, $this->key, $this->decryptIV); } return $this->paddable ? $this->_unpad($plaintext) : $plaintext; } if (strlen($this->key) <= 8) { $this->des[0]->mode = $this->mode; $plaintext = $this->des[0]->decrypt($ciphertext); return $this->paddable ? $this->_unpad($plaintext) : $plaintext; } $des = $this->des; $buffer = &$this->enbuffer; $continuousBuffer = $this->continuousBuffer; $plaintext = ''; switch ($this->mode) { case CRYPT_DES_MODE_ECB: for ($i = 0; $i < strlen($ciphertext); $i+=8) { $block = substr($ciphertext, $i, 8); $block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT); $block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT); $block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT); $plaintext.= $block; } break; case CRYPT_DES_MODE_CBC: $xor = $this->decryptIV; for ($i = 0; $i < strlen($ciphertext); $i+=8) { $orig = $block = substr($ciphertext, $i, 8); $block = $des[2]->_processBlock($block, CRYPT_DES_DECRYPT); $block = $des[1]->_processBlock($block, CRYPT_DES_ENCRYPT); $block = $des[0]->_processBlock($block, CRYPT_DES_DECRYPT); $plaintext.= $block ^ $xor; $xor = $orig; } if ($this->continuousBuffer) { $this->decryptIV = $xor; } break; case CRYPT_DES_MODE_CTR: $xor = $this->decryptIV; if (strlen($buffer)) { for ($i = 0; $i < strlen($ciphertext); $i+=8) { $block = substr($ciphertext, $i, 8); $key = $this->_generate_xor(8, $xor); $key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT); $key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT); $key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT); $buffer.= $key; $key = $this->_string_shift($buffer, 8); $plaintext.= $block ^ $key; } } else { for ($i = 0; $i < strlen($ciphertext); $i+=8) { $block = substr($ciphertext, $i, 8); $key = $this->_generate_xor(8, $xor); $key = $des[0]->_processBlock($key, CRYPT_DES_ENCRYPT); $key = $des[1]->_processBlock($key, CRYPT_DES_DECRYPT); $key = $des[2]->_processBlock($key, CRYPT_DES_ENCRYPT); $plaintext.= $block ^ $key; } } if ($this->continuousBuffer) { $this->decryptIV = $xor; if ($start = strlen($plaintext) & 7) { $buffer = substr($key, $start) . $buffer; } } break; case CRYPT_DES_MODE_CFB: if (!empty($buffer['ciphertext'])) { $plaintext = $ciphertext ^ substr($this->decryptIV, strlen($buffer['ciphertext'])); $buffer['ciphertext'].= substr($ciphertext, 0, strlen($plaintext)); if (strlen($buffer['ciphertext']) == 8) { $xor = $des[0]->_processBlock($buffer['ciphertext'], CRYPT_DES_ENCRYPT); $xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT); $xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT); $buffer['ciphertext'] = ''; } $start = strlen($plaintext); $block = $this->decryptIV; } else { $plaintext = ''; $xor = $des[0]->_processBlock($this->decryptIV, CRYPT_DES_ENCRYPT); $xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT); $xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT); $start = 0; } for ($i = $start; $i < strlen($ciphertext); $i+=8) { $block = substr($ciphertext, $i, 8); $plaintext.= $block ^ $xor; if ($continuousBuffer && strlen($block) != 8) { $buffer['ciphertext'].= $block; $block = $xor; } else if (strlen($block) == 8) { $xor = $des[0]->_processBlock($block, CRYPT_DES_ENCRYPT); $xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT); $xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT); } } if ($this->continuousBuffer) { $this->decryptIV = $block; } break; case CRYPT_DES_MODE_OFB: $xor = $this->decryptIV; if (strlen($buffer)) { for ($i = 0; $i < strlen($ciphertext); $i+=8) { $xor = $des[0]->_processBlock($xor, CRYPT_DES_ENCRYPT); $xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT); $xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT); $buffer.= $xor; $key = $this->_string_shift($buffer, 8); $plaintext.= substr($ciphertext, $i, 8) ^ $key; } } else { for ($i = 0; $i < strlen($ciphertext); $i+=8) { $xor = $des[0]->_processBlock($xor, CRYPT_DES_ENCRYPT); $xor = $des[1]->_processBlock($xor, CRYPT_DES_DECRYPT); $xor = $des[2]->_processBlock($xor, CRYPT_DES_ENCRYPT); $plaintext.= substr($ciphertext, $i, 8) ^ $xor; } $key = $xor; } if ($this->continuousBuffer) { $this->decryptIV = $xor; if ($start = strlen($ciphertext) & 7) { $buffer = substr($key, $start) . $buffer; } } } return $this->paddable ? $this->_unpad($plaintext) : $plaintext; } /** * 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: * * * echo $des->encrypt(substr($plaintext, 0, 8)); * echo $des->encrypt(substr($plaintext, 8, 8)); * * * echo $des->encrypt($plaintext); * * * The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates * another, as demonstrated with the following: * * * $des->encrypt(substr($plaintext, 0, 8)); * echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8))); * * * echo $des->decrypt($des->encrypt(substr($plaintext, 8, 8))); * * * 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_TripleDES::disableContinuousBuffer() * @access public */ function enableContinuousBuffer() { $this->continuousBuffer = true; if ($this->mode == CRYPT_DES_MODE_3CBC) { $this->des[0]->enableContinuousBuffer(); $this->des[1]->enableContinuousBuffer(); $this->des[2]->enableContinuousBuffer(); } } /** * Treat consecutive packets as if they are a discontinuous buffer. * * The default behavior. * * @see Crypt_TripleDES::enableContinuousBuffer() * @access public */ function disableContinuousBuffer() { $this->continuousBuffer = false; $this->encryptIV = $this->iv; $this->decryptIV = $this->iv; if ($this->mode == CRYPT_DES_MODE_3CBC) { $this->des[0]->disableContinuousBuffer(); $this->des[1]->disableContinuousBuffer(); $this->des[2]->disableContinuousBuffer(); } } /** * Pad "packets". * * DES works by encrypting eight bytes at a time. If you ever need to encrypt or decrypt something that's not * a multiple of eight, it becomes necessary to pad the input so that it's length is a multiple of eight. * * Padding is enabled by default. Sometimes, however, it is undesirable to pad strings. Such is the case in SSH1, * where "packets" are padded with random bytes before being encrypted. Unpad these packets and you risk stripping * away characters that shouldn't be stripped away. (SSH knows how many bytes are added because the length is * transmitted separately) * * @see Crypt_TripleDES::disablePadding() * @access public */ function enablePadding() { $this->padding = true; } /** * Do not pad packets. * * @see Crypt_TripleDES::enablePadding() * @access public */ function disablePadding() { $this->padding = false; } /** * Pads a string * * Pads a string using the RSA PKCS padding standards so that its length is a multiple of the blocksize (8). * 8 - (strlen($text) & 7) bytes are added, each of which is equal to chr(8 - (strlen($text) & 7) * * If padding is disabled and $text is not a multiple of the blocksize, the string will be padded regardless * and padding will, hence forth, be enabled. * * @see Crypt_TripleDES::_unpad() * @access private */ function _pad($text) { $length = strlen($text); if (!$this->padding) { if (($length & 7) == 0) { return $text; } else { user_error("The plaintext's length ($length) is not a multiple of the block size (8)", E_USER_NOTICE); $this->padding = true; } } $pad = 8 - ($length & 7); return str_pad($text, $length + $pad, chr($pad)); } /** * Unpads a string * * If padding is enabled and the reported padding length is invalid the encryption key will be assumed to be wrong * and false will be returned. * * @see Crypt_TripleDES::_pad() * @access private */ function _unpad($text) { if (!$this->padding) { return $text; } $length = ord($text[strlen($text) - 1]); if (!$length || $length > 8) { return false; } return substr($text, 0, -$length); } /** * String Shift * * Inspired by array_shift * * @param String $string * @param optional Integer $index * @return String * @access private */ function _string_shift(&$string, $index = 1) { $substr = substr($string, 0, $index); $string = substr($string, $index); return $substr; } } // vim: ts=4:sw=4:et: // vim6: fdl=1: