<?php /* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */ /** * Pure-PHP implementation of AES. * * Uses mcrypt, if available, and an internal implementation, otherwise. * * PHP versions 4 and 5 * * If {@link Crypt_AES::setKeyLength() setKeyLength()} isn't called, it'll be calculated from * {@link Crypt_AES::setKey() setKey()}. ie. if the key is 128-bits, the key length will be 128-bits. If it's 136-bits * it'll be null-padded to 160-bits and 160 bits will be the key length until {@link Crypt_Rijndael::setKey() setKey()} * is called, again, at which point, it'll be recalculated. * * Since Crypt_AES extends Crypt_Rijndael, some functions are available to be called that, in the context of AES, don't * make a whole lot of sense. {@link Crypt_AES::setBlockLength() setBlockLength()}, for instance. Calling that function, * however possible, won't do anything (AES has a fixed block length whereas Rijndael has a variable one). * * Here's a short example of how to use this library: * <code> * <?php * include('Crypt/AES.php'); * * $aes = new Crypt_AES(); * * $aes->setKey('abcdefghijklmnop'); * * $size = 10 * 1024; * $plaintext = ''; * for ($i = 0; $i < $size; $i++) { * $plaintext.= 'a'; * } * * echo $aes->decrypt($aes->encrypt($plaintext)); * ?> * </code> * * LICENSE: This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, * MA 02111-1307 USA * * @category Crypt * @package Crypt_AES * @author Jim Wigginton <terrafrost@php.net> * @copyright MMVIII Jim Wigginton * @license http://www.gnu.org/licenses/lgpl.txt * @version $Id: AES.php,v 1.7 2010/02/09 06:10:25 terrafrost Exp $ * @link http://phpseclib.sourceforge.net */ /** * Include Crypt_Rijndael */ require_once 'Rijndael.php'; /**#@+ * @access public * @see Crypt_AES::encrypt() * @see Crypt_AES::decrypt() */ /** * Encrypt / decrypt using the Counter mode. * * Set to -1 since that's what Crypt/Random.php uses to index the CTR mode. * * @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Counter_.28CTR.29 */ define('CRYPT_AES_MODE_CTR', -1); /** * Encrypt / decrypt using the Electronic Code Book mode. * * @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Electronic_codebook_.28ECB.29 */ define('CRYPT_AES_MODE_ECB', 1); /** * Encrypt / decrypt using the Code Book Chaining mode. * * @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Cipher-block_chaining_.28CBC.29 */ define('CRYPT_AES_MODE_CBC', 2); /**#@-*/ /**#@+ * @access private * @see Crypt_AES::Crypt_AES() */ /** * Toggles the internal implementation */ define('CRYPT_AES_MODE_INTERNAL', 1); /** * Toggles the mcrypt implementation */ define('CRYPT_AES_MODE_MCRYPT', 2); /**#@-*/ /** * Pure-PHP implementation of AES. * * @author Jim Wigginton <terrafrost@php.net> * @version 0.1.0 * @access public * @package Crypt_AES */ class Crypt_AES extends Crypt_Rijndael { /** * 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_AES::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_AES::decrypt() * @var String * @access private */ var $demcrypt; /** * Default Constructor. * * Determines whether or not the mcrypt extension should be used. $mode should only, at present, be * CRYPT_AES_MODE_ECB or CRYPT_AES_MODE_CBC. If not explictly set, CRYPT_AES_MODE_CBC will be used. * * @param optional Integer $mode * @return Crypt_AES * @access public */ function Crypt_AES($mode = CRYPT_AES_MODE_CBC) { if ( !defined('CRYPT_AES_MODE') ) { switch (true) { case extension_loaded('mcrypt'): // i'd check to see if aes 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_AES_MODE', CRYPT_AES_MODE_MCRYPT); break; default: define('CRYPT_AES_MODE', CRYPT_AES_MODE_INTERNAL); } } switch ( CRYPT_AES_MODE ) { case CRYPT_AES_MODE_MCRYPT: switch ($mode) { case CRYPT_AES_MODE_ECB: $this->mode = MCRYPT_MODE_ECB; break; case CRYPT_AES_MODE_CTR: // ctr doesn't have a constant associated with it even though it appears to be fairly widely // supported. in lieu of knowing just how widely supported it is, i've, for now, opted not to // include a compatibility layer. the layer has been implemented but, for now, is commented out. $this->mode = 'ctr'; //$this->mode = in_array('ctr', mcrypt_list_modes()) ? 'ctr' : CRYPT_AES_MODE_CTR; break; case CRYPT_AES_MODE_CBC: default: $this->mode = MCRYPT_MODE_CBC; } break; default: switch ($mode) { case CRYPT_AES_MODE_ECB: $this->mode = CRYPT_RIJNDAEL_MODE_ECB; break; case CRYPT_AES_MODE_CTR: $this->mode = CRYPT_RIJNDAEL_MODE_CTR; break; case CRYPT_AES_MODE_CBC: default: $this->mode = CRYPT_RIJNDAEL_MODE_CBC; } } if (CRYPT_AES_MODE == CRYPT_AES_MODE_INTERNAL) { parent::Crypt_Rijndael($this->mode); } } /** * Dummy function * * Since Crypt_AES extends Crypt_Rijndael, this function is, technically, available, but it doesn't do anything. * * @access public * @param Integer $length */ function setBlockLength($length) { return; } /** * Encrypts a message. * * $plaintext will be padded with up to 16 additional bytes. Other AES implementations may or may not pad in the * same manner. Other common approaches to padding and the reasons why it's necessary are discussed in the following * URL: * * {@link http://www.di-mgt.com.au/cryptopad.html http://www.di-mgt.com.au/cryptopad.html} * * An alternative to padding is to, separately, send the length of the file. This is what SSH, in fact, does. * strlen($plaintext) will still need to be a multiple of 16, however, arbitrary values can be added to make it that * length. * * @see Crypt_AES::decrypt() * @access public * @param String $plaintext */ function encrypt($plaintext) { if ( CRYPT_AES_MODE == CRYPT_AES_MODE_MCRYPT ) { $this->_mcryptSetup(); /* if ($this->mode == CRYPT_AES_MODE_CTR) { $iv = $this->encryptIV; $xor = mcrypt_generic($this->enmcrypt, $this->_generate_xor(strlen($plaintext), $iv)); $ciphertext = $plaintext ^ $xor; if ($this->continuousBuffer) { $this->encryptIV = $iv; } return $ciphertext; } */ if ($this->mode != 'ctr') { $plaintext = $this->_pad($plaintext); } $ciphertext = mcrypt_generic($this->enmcrypt, $plaintext); if (!$this->continuousBuffer) { mcrypt_generic_init($this->enmcrypt, $this->key, $this->iv); } return $ciphertext; } return parent::encrypt($plaintext); } /** * Decrypts a message. * * If strlen($ciphertext) is not a multiple of 16, null bytes will be added to the end of the string until it is. * * @see Crypt_AES::encrypt() * @access public * @param String $ciphertext */ function decrypt($ciphertext) { if ( CRYPT_AES_MODE == CRYPT_AES_MODE_MCRYPT ) { $this->_mcryptSetup(); /* if ($this->mode == CRYPT_AES_MODE_CTR) { $iv = $this->decryptIV; $xor = mcrypt_generic($this->enmcrypt, $this->_generate_xor(strlen($ciphertext), $iv)); $plaintext = $ciphertext ^ $xor; if ($this->continuousBuffer) { $this->decryptIV = $iv; } return $plaintext; } */ if ($this->mode != 'ctr') { // 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) + 15) & 0xFFFFFFF0, chr(0)); } $plaintext = mdecrypt_generic($this->demcrypt, $ciphertext); if (!$this->continuousBuffer) { mcrypt_generic_init($this->demcrypt, $this->key, $this->iv); } return $this->mode != 'ctr' ? $this->_unpad($plaintext) : $plaintext; } return parent::decrypt($ciphertext); } /** * Setup mcrypt * * Validates all the variables. * * @access private */ function _mcryptSetup() { if (!$this->changed) { return; } if (!$this->explicit_key_length) { // this just copied from Crypt_Rijndael::_setup() $length = strlen($this->key) >> 2; if ($length > 8) { $length = 8; } else if ($length < 4) { $length = 4; } $this->Nk = $length; $this->key_size = $length << 2; } switch ($this->Nk) { case 4: // 128 $this->key_size = 16; break; case 5: // 160 case 6: // 192 $this->key_size = 24; break; case 7: // 224 case 8: // 256 $this->key_size = 32; } $this->key = substr($this->key, 0, $this->key_size); $this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($this->iv, 0, 16), 16, chr(0)); if (!isset($this->enmcrypt)) { $mode = $this->mode; //$mode = $this->mode == CRYPT_AES_MODE_CTR ? MCRYPT_MODE_ECB : $this->mode; $this->demcrypt = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', $mode, ''); $this->enmcrypt = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', $mode, ''); } // else should mcrypt_generic_deinit be called? mcrypt_generic_init($this->demcrypt, $this->key, $this->iv); mcrypt_generic_init($this->enmcrypt, $this->key, $this->iv); $this->changed = false; } /** * Encrypts a block * * Optimized over Crypt_Rijndael's implementation by means of loop unrolling. * * @see Crypt_Rijndael::_encryptBlock() * @access private * @param String $in * @return String */ function _encryptBlock($in) { $state = unpack('N*word', $in); $Nr = $this->Nr; $w = $this->w; $t0 = $this->t0; $t1 = $this->t1; $t2 = $this->t2; $t3 = $this->t3; // addRoundKey and reindex $state $state = array( $state['word1'] ^ $w[0][0], $state['word2'] ^ $w[0][1], $state['word3'] ^ $w[0][2], $state['word4'] ^ $w[0][3] ); // shiftRows + subWord + mixColumns + addRoundKey // we could loop unroll this and use if statements to do more rounds as necessary, but, in my tests, that yields // only a marginal improvement. since that also, imho, hinders the readability of the code, i've opted not to do it. for ($round = 1; $round < $this->Nr; $round++) { $state = array( $t0[$state[0] & 0xFF000000] ^ $t1[$state[1] & 0x00FF0000] ^ $t2[$state[2] & 0x0000FF00] ^ $t3[$state[3] & 0x000000FF] ^ $w[$round][0], $t0[$state[1] & 0xFF000000] ^ $t1[$state[2] & 0x00FF0000] ^ $t2[$state[3] & 0x0000FF00] ^ $t3[$state[0] & 0x000000FF] ^ $w[$round][1], $t0[$state[2] & 0xFF000000] ^ $t1[$state[3] & 0x00FF0000] ^ $t2[$state[0] & 0x0000FF00] ^ $t3[$state[1] & 0x000000FF] ^ $w[$round][2], $t0[$state[3] & 0xFF000000] ^ $t1[$state[0] & 0x00FF0000] ^ $t2[$state[1] & 0x0000FF00] ^ $t3[$state[2] & 0x000000FF] ^ $w[$round][3] ); } // subWord $state = array( $this->_subWord($state[0]), $this->_subWord($state[1]), $this->_subWord($state[2]), $this->_subWord($state[3]) ); // shiftRows + addRoundKey $state = array( ($state[0] & 0xFF000000) ^ ($state[1] & 0x00FF0000) ^ ($state[2] & 0x0000FF00) ^ ($state[3] & 0x000000FF) ^ $this->w[$this->Nr][0], ($state[1] & 0xFF000000) ^ ($state[2] & 0x00FF0000) ^ ($state[3] & 0x0000FF00) ^ ($state[0] & 0x000000FF) ^ $this->w[$this->Nr][1], ($state[2] & 0xFF000000) ^ ($state[3] & 0x00FF0000) ^ ($state[0] & 0x0000FF00) ^ ($state[1] & 0x000000FF) ^ $this->w[$this->Nr][2], ($state[3] & 0xFF000000) ^ ($state[0] & 0x00FF0000) ^ ($state[1] & 0x0000FF00) ^ ($state[2] & 0x000000FF) ^ $this->w[$this->Nr][3] ); return pack('N*', $state[0], $state[1], $state[2], $state[3]); } /** * Decrypts a block * * Optimized over Crypt_Rijndael's implementation by means of loop unrolling. * * @see Crypt_Rijndael::_decryptBlock() * @access private * @param String $in * @return String */ function _decryptBlock($in) { $state = unpack('N*word', $in); $Nr = $this->Nr; $dw = $this->dw; $dt0 = $this->dt0; $dt1 = $this->dt1; $dt2 = $this->dt2; $dt3 = $this->dt3; // addRoundKey and reindex $state $state = array( $state['word1'] ^ $dw[$this->Nr][0], $state['word2'] ^ $dw[$this->Nr][1], $state['word3'] ^ $dw[$this->Nr][2], $state['word4'] ^ $dw[$this->Nr][3] ); // invShiftRows + invSubBytes + invMixColumns + addRoundKey for ($round = $this->Nr - 1; $round > 0; $round--) { $state = array( $dt0[$state[0] & 0xFF000000] ^ $dt1[$state[3] & 0x00FF0000] ^ $dt2[$state[2] & 0x0000FF00] ^ $dt3[$state[1] & 0x000000FF] ^ $dw[$round][0], $dt0[$state[1] & 0xFF000000] ^ $dt1[$state[0] & 0x00FF0000] ^ $dt2[$state[3] & 0x0000FF00] ^ $dt3[$state[2] & 0x000000FF] ^ $dw[$round][1], $dt0[$state[2] & 0xFF000000] ^ $dt1[$state[1] & 0x00FF0000] ^ $dt2[$state[0] & 0x0000FF00] ^ $dt3[$state[3] & 0x000000FF] ^ $dw[$round][2], $dt0[$state[3] & 0xFF000000] ^ $dt1[$state[2] & 0x00FF0000] ^ $dt2[$state[1] & 0x0000FF00] ^ $dt3[$state[0] & 0x000000FF] ^ $dw[$round][3] ); } // invShiftRows + invSubWord + addRoundKey $state = array( $this->_invSubWord(($state[0] & 0xFF000000) ^ ($state[3] & 0x00FF0000) ^ ($state[2] & 0x0000FF00) ^ ($state[1] & 0x000000FF)) ^ $dw[0][0], $this->_invSubWord(($state[1] & 0xFF000000) ^ ($state[0] & 0x00FF0000) ^ ($state[3] & 0x0000FF00) ^ ($state[2] & 0x000000FF)) ^ $dw[0][1], $this->_invSubWord(($state[2] & 0xFF000000) ^ ($state[1] & 0x00FF0000) ^ ($state[0] & 0x0000FF00) ^ ($state[3] & 0x000000FF)) ^ $dw[0][2], $this->_invSubWord(($state[3] & 0xFF000000) ^ ($state[2] & 0x00FF0000) ^ ($state[1] & 0x0000FF00) ^ ($state[0] & 0x000000FF)) ^ $dw[0][3] ); return pack('N*', $state[0], $state[1], $state[2], $state[3]); } } // vim: ts=4:sw=4:et: // vim6: fdl=1: