PHP Decode

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed'); 
/** 
 * CodeIgniter 
 * 
 * An open source application development framework for PHP 5.1.6 or newer 
 * 
 * @package		CodeIgniter 
 * @author		ExpressionEngine Dev Team 
 * @copyright	Copyright (c) 2008 - 2011, EllisLab, Inc. 
 * @license		http://codeigniter.com/user_guide/license.html 
 * @link		http://codeigniter.com 
 * @since		Version 1.0 
 * @filesource 
 */ 
 
// ------------------------------------------------------------------------ 
 
/** 
 * SHA1 Encoding Class 
 * 
 * Purpose: Provides 160 bit hashing using The Secure Hash Algorithm 
 * developed at the National Institute of Standards and Technology. The 40 
 * character SHA1 message hash is computationally infeasible to crack. 
 * 
 * This class is a fallback for servers that are not running PHP greater than 
 * 4.3, or do not have the MHASH library. 
 * 
 * This class is based on two scripts: 
 * 
 * Marcus Campbell's PHP implementation (GNU license) 
 * http://www.tecknik.net/sha-1/ 
 * 
 * ...which is based on Paul Johnston's JavaScript version 
 * (BSD license). http://pajhome.org.uk/ 
 * 
 * I encapsulated the functions and wrote one additional method to fix 
 * a hex conversion bug. - Rick Ellis 
 * 
 * @package		CodeIgniter 
 * @subpackage	Libraries 
 * @category	Encryption 
 * @author		ExpressionEngine Dev Team 
 * @link		http://codeigniter.com/user_guide/general/encryption.html 
 */ 
class CI_SHA1 { 
 
	public function __construct() 
	{ 
		log_message('debug', "SHA1 Class Initialized"); 
	} 
 
	/** 
	 * Generate the Hash 
	 * 
	 * @access	public 
	 * @param	string 
	 * @return	string 
	 */ 
	function generate($str) 
	{ 
		$n = ((strlen($str) + 8) >> 6) + 1; 
 
		for ($i = 0; $i < $n * 16; $i++) 
		{ 
			$x[$i] = 0; 
		} 
 
		for ($i = 0; $i < strlen($str); $i++) 
		{ 
			$x[$i >> 2] |= ord(substr($str, $i, 1)) << (24 - ($i % 4) * 8); 
		} 
 
		$x[$i >> 2] |= 0x80 << (24 - ($i % 4) * 8); 
 
		$x[$n * 16 - 1] = strlen($str) * 8; 
 
		$a =  1732584193; 
		$b = -271733879; 
		$c = -1732584194; 
		$d =  271733878; 
		$e = -1009589776; 
 
		for ($i = 0; $i < count($x); $i += 16) 
		{ 
			$olda = $a; 
			$oldb = $b; 
			$oldc = $c; 
			$oldd = $d; 
			$olde = $e; 
 
			for ($j = 0; $j < 80; $j++) 
			{ 
				if ($j < 16) 
				{ 
					$w[$j] = $x[$i + $j]; 
				} 
				else 
				{ 
					$w[$j] = $this->_rol($w[$j - 3] ^ $w[$j - 8] ^ $w[$j - 14] ^ $w[$j - 16], 1); 
				} 
 
				$t = $this->_safe_add($this->_safe_add($this->_rol($a, 5), $this->_ft($j, $b, $c, $d)), $this->_safe_add($this->_safe_add($e, $w[$j]), $this->_kt($j))); 
 
				$e = $d; 
				$d = $c; 
				$c = $this->_rol($b, 30); 
				$b = $a; 
				$a = $t; 
			} 
 
			$a = $this->_safe_add($a, $olda); 
			$b = $this->_safe_add($b, $oldb); 
			$c = $this->_safe_add($c, $oldc); 
			$d = $this->_safe_add($d, $oldd); 
			$e = $this->_safe_add($e, $olde); 
		} 
 
		return $this->_hex($a).$this->_hex($b).$this->_hex($c).$this->_hex($d).$this->_hex($e); 
	} 
 
	// -------------------------------------------------------------------- 
 
	/** 
	 * Convert a decimal to hex 
	 * 
	 * @access	private 
	 * @param	string 
	 * @return	string 
	 */ 
	function _hex($str) 
	{ 
		$str = dechex($str); 
 
		if (strlen($str) == 7) 
		{ 
			$str = '0'.$str; 
		} 
 
		return $str; 
	} 
 
	// -------------------------------------------------------------------- 
 
	/** 
	 *  Return result based on iteration 
	 * 
	 * @access	private 
	 * @return	string 
	 */ 
	function _ft($t, $b, $c, $d) 
	{ 
		if ($t < 20) 
			return ($b & $c) | ((~$b) & $d); 
		if ($t < 40) 
			return $b ^ $c ^ $d; 
		if ($t < 60) 
			return ($b & $c) | ($b & $d) | ($c & $d); 
 
		return $b ^ $c ^ $d; 
	} 
 
	// -------------------------------------------------------------------- 
 
	/** 
	 * Determine the additive constant 
	 * 
	 * @access	private 
	 * @return	string 
	 */ 
	function _kt($t) 
	{ 
		if ($t < 20) 
		{ 
			return 1518500249; 
		} 
		else if ($t < 40) 
		{ 
			return 1859775393; 
		} 
		else if ($t < 60) 
		{ 
			return -1894007588; 
		} 
		else 
		{ 
			return -899497514; 
		} 
	} 
 
	// -------------------------------------------------------------------- 
 
	/** 
	 * Add integers, wrapping at 2^32 
	 * 
	 * @access	private 
	 * @return	string 
	 */ 
	function _safe_add($x, $y) 
	{ 
		$lsw = ($x & 0xFFFF) + ($y & 0xFFFF); 
		$msw = ($x >> 16) + ($y >> 16) + ($lsw >> 16); 
 
		return ($msw << 16) | ($lsw & 0xFFFF); 
	} 
 
	// -------------------------------------------------------------------- 
 
	/** 
	 * Bitwise rotate a 32-bit number 
	 * 
	 * @access	private 
	 * @return	integer 
	 */ 
	function _rol($num, $cnt) 
	{ 
		return ($num << $cnt) | $this->_zero_fill($num, 32 - $cnt); 
	} 
 
	// -------------------------------------------------------------------- 
 
	/** 
	 * Pad string with zero 
	 * 
	 * @access	private 
	 * @return	string 
	 */ 
	function _zero_fill($a, $b) 
	{ 
		$bin = decbin($a); 
 
		if (strlen($bin) < $b) 
		{ 
			$bin = 0; 
		} 
		else 
		{ 
			$bin = substr($bin, 0, strlen($bin) - $b); 
		} 
 
		for ($i=0; $i < $b; $i++) 
		{ 
			$bin = "0".$bin; 
		} 
 
		return bindec($bin); 
	} 
} 
// END CI_SHA 
 
/* End of file Sha1.php */ 
/* Location: ./system/libraries/Sha1.php */ ?>