class.rc4crypt.php

<?php

	/* vim: set expandtab shiftwidth=4 softtabstop=4 tabstop=4: */

	/**
	 * RC4Crypt 3.2
	 *
	 * RC4Crypt is a petite library that allows you to use RC4
	 * encryption easily in PHP. It's OO and can produce outputs
	 * in binary and hex.
	 *
	 * (C) Copyright 2006 Mukul Sabharwal [http://mjsabby.com]
	 *     All Rights Reserved
	 *
	 * @link http://rc4crypt.devhome.org
	 * @author Mukul Sabharwal <mjsabby@gmail.com>
	 * @version $Id: class.rc4crypt.php,v 3.2 2006/03/10 05:47:24 mukul Exp $
	 * @copyright Copyright &copy; 2006 Mukul Sabharwal
	 * @license http://www.gnu.org/copyleft/gpl.html
	 * @package RC4Crypt
	 */

	/**
	 * RC4 Class
	 * @package RC4Crypt
	 */
	class rc4crypt {
		/**
		 * The symmetric encryption function
		 *
		 * @param string $pwd Key to encrypt with (can be binary of hex)
		 * @param string $data Content to be encrypted
		 * @param bool $ispwdHex Key passed is in hexadecimal or not
		 * @access public
		 * @return string
		 */
		function rc4 ($pwd, $data, $ispwdHex = 0)
		{
			if ($pwd=='') // if no password specified
				$pwd = 'password'; //use this simple one, only for altering the data
			if ($ispwdHex)
				$pwd = @pack('H*', $pwd); // valid input, please!

			$key[] = '';
			$box[] = '';
			$cipher = '';

			$pwd_length = strlen($pwd);
			$data_length = strlen($data);

			for ($i = 0; $i < 256; $i++)
			{
				$key[$i] = ord($pwd[$i % $pwd_length]);
				$box[$i] = $i;
			}
			for ($j = $i = 0; $i < 256; $i++)
			{
				$j = ($j + $box[$i] + $key[$i]) % 256;
				$tmp = $box[$i];
				$box[$i] = $box[$j];
				$box[$j] = $tmp;
			}
			for ($a = $j = $i = 0; $i < $data_length; $i++)
			{
				$a = ($a + 1) % 256;
				$j = ($j + $box[$a]) % 256;
				$tmp = $box[$a];
				$box[$a] = $box[$j];
				$box[$j] = $tmp;
				$k = $box[(($box[$a] + $box[$j]) % 256)];
				$cipher .= chr(ord($data[$i]) ^ $k);
			}
			return $cipher;
		}
		/**
		 * Decryption, recall encryption
		 *
		 * @param string $pwd Key to decrypt with (can be binary of hex)
		 * @param string $data Content to be decrypted (alphabetically encoded)
		 * @param bool $ispwdHex Key passed is in hexadecimal or not
		 * @access public
		 * @return string
		 */
		function decrypt ($pwd, $data, $ispwdHex = 0)
		{
			//convert ascii to binary
			$binary = ''; //binary string
			$length = strlen($data);
			for ($i=0; $i<$length; $i+=2)
			{
				$x1=ord($data[$i])-65;
				$x2=ord($data[$i+1])-65;
				$binary .= chr($x1 + ($x2 << 4));
			}
			//decrypt binary data
			$data = rc4crypt::rc4($pwd, $binary, $ispwdHex);
			return $data;
		}
		
		function encrypt ($pwd, $data, $ispwdHex = 0)
		{
			//encrypt binary data
			$data = rc4crypt::rc4($pwd, $data, $ispwdHex);
			//convert binary to ascii (chars 65-80)
			$length = strlen($data);
			$alpha = ''; //alpha string
			for ($i = 0; $i < $length; $i++)
			{
				$x = ord($data[$i]);
				$x1 = $x & 0x0f;
				$x2 = ($x & 0xf0) >> 4;
				$alpha .= chr($x1+65).chr($x2+65);
			}
			return $alpha;
		}
	}
?>