* setKey('abcdefgh'); * * $size = 10 * 1024; * $plaintext = ''; * for ($i = 0; $i < $size; $i++) { * $plaintext.= 'a'; * } * * echo $rc4->decrypt($rc4->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_RC4 * @author Jim Wigginton * @copyright MMVII Jim Wigginton * @license http://www.opensource.org/licenses/mit-license.html MIT License * @link http://phpseclib.sourceforge.net */ /**#@+ * @access private * @see Crypt_RC4::Crypt_RC4() */ /** * Toggles the internal implementation */ define('CRYPT_RC4_MODE_INTERNAL', 1); /** * Toggles the mcrypt implementation */ define('CRYPT_RC4_MODE_MCRYPT', 2); /**#@-*/ /**#@+ * @access private * @see Crypt_RC4::_crypt() */ define('CRYPT_RC4_ENCRYPT', 0); define('CRYPT_RC4_DECRYPT', 1); /**#@-*/ /** * Pure-PHP implementation of RC4. * * @author Jim Wigginton * @version 0.1.0 * @access public * @package Crypt_RC4 */ class Crypt_RC4 { /** * The Key * * @see Crypt_RC4::setKey() * @var String * @access private */ var $key = "\0"; /** * The Key Stream for encryption * * If CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT, this will be equal to the mcrypt object * * @see Crypt_RC4::setKey() * @var Array * @access private */ var $encryptStream = false; /** * The Key Stream for decryption * * If CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT, this will be equal to the mcrypt object * * @see Crypt_RC4::setKey() * @var Array * @access private */ var $decryptStream = false; /** * The $i and $j indexes for encryption * * @see Crypt_RC4::_crypt() * @var Integer * @access private */ var $encryptIndex = 0; /** * The $i and $j indexes for decryption * * @see Crypt_RC4::_crypt() * @var Integer * @access private */ var $decryptIndex = 0; /** * The Encryption Algorithm * * Only used if CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT. Only possible values are MCRYPT_RC4 or MCRYPT_ARCFOUR. * * @see Crypt_RC4::Crypt_RC4() * @var Integer * @access private */ var $mode; /** * Continuous Buffer status * * @see Crypt_RC4::enableContinuousBuffer() * @var Boolean * @access private */ var $continuousBuffer = false; /** * Default Constructor. * * Determines whether or not the mcrypt extension should be used. * * @return Crypt_RC4 * @access public */ function Crypt_RC4() { if ( !defined('CRYPT_RC4_MODE') ) { switch (true) { case extension_loaded('mcrypt') && (defined('MCRYPT_ARCFOUR') || defined('MCRYPT_RC4')) && in_array('arcfour', mcrypt_list_algorithms()): define('CRYPT_RC4_MODE', CRYPT_RC4_MODE_MCRYPT); break; default: define('CRYPT_RC4_MODE', CRYPT_RC4_MODE_INTERNAL); } } switch ( CRYPT_RC4_MODE ) { case CRYPT_RC4_MODE_MCRYPT: switch (true) { case defined('MCRYPT_ARCFOUR'): $this->mode = MCRYPT_ARCFOUR; break; case defined('MCRYPT_RC4'); $this->mode = MCRYPT_RC4; } $this->encryptStream = mcrypt_module_open($this->mode, '', MCRYPT_MODE_STREAM, ''); $this->decryptStream = mcrypt_module_open($this->mode, '', MCRYPT_MODE_STREAM, ''); } } /** * Sets the key. * * Keys can be between 1 and 256 bytes long. If they are longer then 256 bytes, the first 256 bytes will * be used. If no key is explicitly set, it'll be assumed to be a single null byte. * * @access public * @param String $key */ function setKey($key) { $this->key = $key; if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) { mcrypt_generic_init($this->encryptStream, $this->key, ''); mcrypt_generic_init($this->decryptStream, $this->key, ''); return; } $keyLength = strlen($key); $keyStream = array(); for ($i = 0; $i < 256; $i++) { $keyStream[$i] = $i; } $j = 0; for ($i = 0; $i < 256; $i++) { $j = ($j + $keyStream[$i] + ord($key[$i % $keyLength])) & 255; $temp = $keyStream[$i]; $keyStream[$i] = $keyStream[$j]; $keyStream[$j] = $temp; } $this->encryptIndex = $this->decryptIndex = array(0, 0); $this->encryptStream = $this->decryptStream = $keyStream; } /** * Sets the password. * * Depending on what $method is set to, setPassword()'s (optional) parameters are as follows: * {@link http://en.wikipedia.org/wiki/PBKDF2 pbkdf2}: * $hash, $salt, $count, $dkLen * * @param String $password * @param optional String $method * @access public */ function setPassword($password, $method = 'pbkdf2') { $key = ''; switch ($method) { default: // 'pbkdf2' list(, , $hash, $salt, $count) = func_get_args(); if (!isset($hash)) { $hash = 'sha1'; } // WPA and WPA2 use the SSID as the salt if (!isset($salt)) { $salt = 'phpseclib/salt'; } // RFC2898#section-4.2 uses 1,000 iterations by default // WPA and WPA2 use 4,096. if (!isset($count)) { $count = 1000; } if (!isset($dkLen)) { $dkLen = 128; } if (!class_exists('Crypt_Hash')) { require_once('Crypt/Hash.php'); } $i = 1; while (strlen($key) < $dkLen) { //$dk.= $this->_pbkdf($password, $salt, $count, $i++); $hmac = new Crypt_Hash(); $hmac->setHash($hash); $hmac->setKey($password); $f = $u = $hmac->hash($salt . pack('N', $i++)); for ($j = 2; $j <= $count; $j++) { $u = $hmac->hash($u); $f^= $u; } $key.= $f; } } $this->setKey(substr($key, 0, $dkLen)); } /** * Dummy function. * * Some protocols, such as WEP, prepend an "initialization vector" to the key, effectively creating a new key [1]. * If you need to use an initialization vector in this manner, feel free to prepend it to the key, yourself, before * calling setKey(). * * [1] WEP's initialization vectors (IV's) are used in a somewhat insecure way. Since, in that protocol, * the IV's are relatively easy to predict, an attack described by * {@link http://www.drizzle.com/~aboba/IEEE/rc4_ksaproc.pdf Scott Fluhrer, Itsik Mantin, and Adi Shamir} * can be used to quickly guess at the rest of the key. The following links elaborate: * * {@link http://www.rsa.com/rsalabs/node.asp?id=2009 http://www.rsa.com/rsalabs/node.asp?id=2009} * {@link http://en.wikipedia.org/wiki/Related_key_attack http://en.wikipedia.org/wiki/Related_key_attack} * * @param String $iv * @see Crypt_RC4::setKey() * @access public */ function setIV($iv) { } /** * Encrypts a message. * * @see Crypt_RC4::_crypt() * @access public * @param String $plaintext */ function encrypt($plaintext) { return $this->_crypt($plaintext, CRYPT_RC4_ENCRYPT); } /** * Decrypts a message. * * $this->decrypt($this->encrypt($plaintext)) == $this->encrypt($this->encrypt($plaintext)). * Atleast if the continuous buffer is disabled. * * @see Crypt_RC4::_crypt() * @access public * @param String $ciphertext */ function decrypt($ciphertext) { return $this->_crypt($ciphertext, CRYPT_RC4_DECRYPT); } /** * Encrypts or decrypts a message. * * @see Crypt_RC4::encrypt() * @see Crypt_RC4::decrypt() * @access private * @param String $text * @param Integer $mode */ function _crypt($text, $mode) { if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) { $keyStream = $mode == CRYPT_RC4_ENCRYPT ? 'encryptStream' : 'decryptStream'; if (!$this->continuousBuffer) { mcrypt_generic_init($this->$keyStream, $this->key, ''); } return mcrypt_generic($this->$keyStream, $text); } if ($this->encryptStream === false) { $this->setKey($this->key); } switch ($mode) { case CRYPT_RC4_ENCRYPT: $keyStream = $this->encryptStream; list($i, $j) = $this->encryptIndex; break; case CRYPT_RC4_DECRYPT: $keyStream = $this->decryptStream; list($i, $j) = $this->decryptIndex; } $newText = ''; for ($k = 0; $k < strlen($text); $k++) { $i = ($i + 1) & 255; $j = ($j + $keyStream[$i]) & 255; $temp = $keyStream[$i]; $keyStream[$i] = $keyStream[$j]; $keyStream[$j] = $temp; $temp = $keyStream[($keyStream[$i] + $keyStream[$j]) & 255]; $newText.= chr(ord($text[$k]) ^ $temp); } if ($this->continuousBuffer) { switch ($mode) { case CRYPT_RC4_ENCRYPT: $this->encryptStream = $keyStream; $this->encryptIndex = array($i, $j); break; case CRYPT_RC4_DECRYPT: $this->decryptStream = $keyStream; $this->decryptIndex = array($i, $j); } } return $newText; } /** * 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 $rc4->encrypt(substr($plaintext, 0, 8)); * echo $rc4->encrypt(substr($plaintext, 8, 8)); * * * echo $rc4->encrypt($plaintext); * * * The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates * another, as demonstrated with the following: * * * $rc4->encrypt(substr($plaintext, 0, 8)); * echo $rc4->decrypt($des->encrypt(substr($plaintext, 8, 8))); * * * echo $rc4->decrypt($des->encrypt(substr($plaintext, 8, 8))); * * * With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different * outputs. The reason is due to the fact that the initialization vector's change after every encryption / * decryption round when the continuous buffer is enabled. When it's disabled, they remain constant. * * Put another way, when the continuous buffer is enabled, the state of the Crypt_DES() object changes after each * encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that * continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them), * however, they are also less intuitive and more likely to cause you problems. * * @see Crypt_RC4::disableContinuousBuffer() * @access public */ function enableContinuousBuffer() { if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_MCRYPT ) { mcrypt_generic_init($this->encryptStream, $this->key, ''); mcrypt_generic_init($this->decryptStream, $this->key, ''); } $this->continuousBuffer = true; } /** * Treat consecutive packets as if they are a discontinuous buffer. * * The default behavior. * * @see Crypt_RC4::enableContinuousBuffer() * @access public */ function disableContinuousBuffer() { if ( CRYPT_RC4_MODE == CRYPT_RC4_MODE_INTERNAL ) { $this->encryptIndex = $this->decryptIndex = array(0, 0); $this->encryptStream = $this->decryptStream = false; } $this->continuousBuffer = false; } /** * Dummy function. * * Since RC4 is a stream cipher and not a block cipher, no padding is necessary. The only reason this function is * included is so that you can switch between a block cipher and a stream cipher transparently. * * @see Crypt_RC4::disablePadding() * @access public */ function enablePadding() { } /** * Dummy function. * * @see Crypt_RC4::enablePadding() * @access public */ function disablePadding() { } } // vim: ts=4:sw=4:et: // vim6: fdl=1: