se/SE/se-lib/Crypt.php

<?php

class Crypt {

	public static function getDesKey() {
		// TODO: mv to Config
		$crypto_key_des = 'c+X_d!4eCgOG+*R6D5j+zOP5';
		return $crypto_key_des;
	}

	/**
	 * Encrypt using 3DES
	 *
	 * @param string $clear clear text input
	 * @param string $key encryption key to retrieve from the configuration, defaults to 'des_key'
	 * @param boolean $base64 whether or not to base64_encode() the result before returning
	 *
	 * @return string encrypted text
	 */
	public static function encrypt($clear, $key = 'des_key', $base64 = true) {
		if (!$clear) {
				return '';
		}

		/*-
		 * Add a single canary byte to the end of the clear text, which
		 * will help find out how much of padding will need to be removed
		 * upon decryption; see http://php.net/mcrypt_generic#68082
		 */
		$clear = pack("a*H2", $clear, "80");

		if (function_exists('mcrypt_module_open') &&
				($td = mcrypt_module_open(MCRYPT_TripleDES, "", MCRYPT_MODE_CBC, ""))
		) {
			$iv = self::create_iv(mcrypt_enc_get_iv_size($td));
			mcrypt_generic_init($td, self::getDesKey(), $iv);
			$cipher = $iv . mcrypt_generic($td, $clear);
			mcrypt_generic_deinit($td);
			mcrypt_module_close($td);
		}
		else {
			$des_iv_size = 8;
			$iv = self::create_iv($des_iv_size);
			$cipher = $iv . self::des(self::getDesKey(), $clear, 1, 1, $iv);
		}

		return $base64 ? base64_encode($cipher) : $cipher;
	}

	/**
	 * Decrypt 3DES-encrypted string
	 *
	 * @param string $cipher encrypted text
	 * @param string $key encryption key to retrieve from the configuration, defaults to 'des_key'
	 * @param boolean $base64 whether or not input is base64-encoded
	 *
	 * @return string decrypted text
	 */
	public static function decrypt($cipher, $key = 'des_key', $base64 = true) {
		if (!$cipher) {
			return '';
		}

		$cipher = $base64 ? base64_decode($cipher) : $cipher;

		if (function_exists('mcrypt_module_open') &&
				($td = mcrypt_module_open(MCRYPT_TripleDES, "", MCRYPT_MODE_CBC, ""))
		) {
			$iv_size = mcrypt_enc_get_iv_size($td);
			$iv = substr($cipher, 0, $iv_size);

			// session corruption? (#1485970)
			if (strlen($iv) < $iv_size) {
					return '';
			}

			$cipher = substr($cipher, $iv_size);
			mcrypt_generic_init($td, self::getDesKey(), $iv);
			$clear = mdecrypt_generic($td, $cipher);
			mcrypt_generic_deinit($td);
			mcrypt_module_close($td);
		}
		else {
			$des_iv_size = 8;
			$iv = substr($cipher, 0, $des_iv_size);
			$cipher = substr($cipher, $des_iv_size);
			$clear = self::des(self::getDesKey(), $cipher, 0, 1, $iv);
		}

		/*-
		 * Trim PHP's padding and the canary byte; see note in
		 * rcube::encrypt() and http://php.net/mcrypt_generic#68082
		 */
		$clear = substr(rtrim($clear, "\0"), 0, -1);

		return $clear;
	}

	/**
	 * Generates encryption initialization vector (IV)
	 *
	 * @param int Vector size
	 *
	 * @return string Vector string
	 */
	public static function create_iv($size) {
		// mcrypt_create_iv() can be slow when system lacks entrophy
		// we'll generate IV vector manually
		$iv = '';
		for ($i = 0; $i < $size; $i++) {
			$iv .= chr(mt_rand(0, 255));
		}

		return $iv;
	}

	//PHP version
	//Paul Tero, July 2001
	//http://www.shopable.co.uk/des.html
	//
	//Optimised for performance with large blocks by Michael Hayworth, November 2001
	//http://www.netdealing.com
	//
	//Converted from JavaScript to PHP by Jim Gibbs, June 2004
	//
	//THIS SOFTWARE IS PROVIDED "AS IS" AND
	//ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	//IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	//ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
	//FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	//DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	//OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	//HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	//LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	//OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	//SUCH DAMAGE.

	//des
	//this takes the key, the message, and whether to encrypt or decrypt
	public static function des($key, $message, $encrypt, $mode, $iv) {
		//declaring this locally speeds things up a bit
		$spfunction1 = array (0x1010400,0,0x10000,0x1010404,0x1010004,0x10404,0x4,0x10000,0x400,0x1010400,0x1010404,0x400,0x1000404,0x1010004,0x1000000,0x4,0x404,0x1000400,0x1000400,0x10400,0x10400,0x1010000,0x1010000,0x1000404,0x10004,0x1000004,0x1000004,0x10004,0,0x404,0x10404,0x1000000,0x10000,0x1010404,0x4,0x1010000,0x1010400,0x1000000,0x1000000,0x400,0x1010004,0x10000,0x10400,0x1000004,0x400,0x4,0x1000404,0x10404,0x1010404,0x10004,0x1010000,0x1000404,0x1000004,0x404,0x10404,0x1010400,0x404,0x1000400,0x1000400,0,0x10004,0x10400,0,0x1010004);
		$spfunction2 = array (-0x7fef7fe0,-0x7fff8000,0x8000,0x108020,0x100000,0x20,-0x7fefffe0,-0x7fff7fe0,-0x7fffffe0,-0x7fef7fe0,-0x7fef8000,-0x80000000,-0x7fff8000,0x100000,0x20,-0x7fefffe0,0x108000,0x100020,-0x7fff7fe0,0,-0x80000000,0x8000,0x108020,-0x7ff00000,0x100020,-0x7fffffe0,0,0x108000,0x8020,-0x7fef8000,-0x7ff00000,0x8020,0,0x108020,-0x7fefffe0,0x100000,-0x7fff7fe0,-0x7ff00000,-0x7fef8000,0x8000,-0x7ff00000,-0x7fff8000,0x20,-0x7fef7fe0,0x108020,0x20,0x8000,-0x80000000,0x8020,-0x7fef8000,0x100000,-0x7fffffe0,0x100020,-0x7fff7fe0,-0x7fffffe0,0x100020,0x108000,0,-0x7fff8000,0x8020,-0x80000000,-0x7fefffe0,-0x7fef7fe0,0x108000);
		$spfunction3 = array (0x208,0x8020200,0,0x8020008,0x8000200,0,0x20208,0x8000200,0x20008,0x8000008,0x8000008,0x20000,0x8020208,0x20008,0x8020000,0x208,0x8000000,0x8,0x8020200,0x200,0x20200,0x8020000,0x8020008,0x20208,0x8000208,0x20200,0x20000,0x8000208,0x8,0x8020208,0x200,0x8000000,0x8020200,0x8000000,0x20008,0x208,0x20000,0x8020200,0x8000200,0,0x200,0x20008,0x8020208,0x8000200,0x8000008,0x200,0,0x8020008,0x8000208,0x20000,0x8000000,0x8020208,0x8,0x20208,0x20200,0x8000008,0x8020000,0x8000208,0x208,0x8020000,0x20208,0x8,0x8020008,0x20200);
		$spfunction4 = array (0x802001,0x2081,0x2081,0x80,0x802080,0x800081,0x800001,0x2001,0,0x802000,0x802000,0x802081,0x81,0,0x800080,0x800001,0x1,0x2000,0x800000,0x802001,0x80,0x800000,0x2001,0x2080,0x800081,0x1,0x2080,0x800080,0x2000,0x802080,0x802081,0x81,0x800080,0x800001,0x802000,0x802081,0x81,0,0,0x802000,0x2080,0x800080,0x800081,0x1,0x802001,0x2081,0x2081,0x80,0x802081,0x81,0x1,0x2000,0x800001,0x2001,0x802080,0x800081,0x2001,0x2080,0x800000,0x802001,0x80,0x800000,0x2000,0x802080);
		$spfunction5 = array (0x100,0x2080100,0x2080000,0x42000100,0x80000,0x100,0x40000000,0x2080000,0x40080100,0x80000,0x2000100,0x40080100,0x42000100,0x42080000,0x80100,0x40000000,0x2000000,0x40080000,0x40080000,0,0x40000100,0x42080100,0x42080100,0x2000100,0x42080000,0x40000100,0,0x42000000,0x2080100,0x2000000,0x42000000,0x80100,0x80000,0x42000100,0x100,0x2000000,0x40000000,0x2080000,0x42000100,0x40080100,0x2000100,0x40000000,0x42080000,0x2080100,0x40080100,0x100,0x2000000,0x42080000,0x42080100,0x80100,0x42000000,0x42080100,0x2080000,0,0x40080000,0x42000000,0x80100,0x2000100,0x40000100,0x80000,0,0x40080000,0x2080100,0x40000100);
		$spfunction6 = array (0x20000010,0x20400000,0x4000,0x20404010,0x20400000,0x10,0x20404010,0x400000,0x20004000,0x404010,0x400000,0x20000010,0x400010,0x20004000,0x20000000,0x4010,0,0x400010,0x20004010,0x4000,0x404000,0x20004010,0x10,0x20400010,0x20400010,0,0x404010,0x20404000,0x4010,0x404000,0x20404000,0x20000000,0x20004000,0x10,0x20400010,0x404000,0x20404010,0x400000,0x4010,0x20000010,0x400000,0x20004000,0x20000000,0x4010,0x20000010,0x20404010,0x404000,0x20400000,0x404010,0x20404000,0,0x20400010,0x10,0x4000,0x20400000,0x404010,0x4000,0x400010,0x20004010,0,0x20404000,0x20000000,0x400010,0x20004010);
		$spfunction7 = array (0x200000,0x4200002,0x4000802,0,0x800,0x4000802,0x200802,0x4200800,0x4200802,0x200000,0,0x4000002,0x2,0x4000000,0x4200002,0x802,0x4000800,0x200802,0x200002,0x4000800,0x4000002,0x4200000,0x4200800,0x200002,0x4200000,0x800,0x802,0x4200802,0x200800,0x2,0x4000000,0x200800,0x4000000,0x200800,0x200000,0x4000802,0x4000802,0x4200002,0x4200002,0x2,0x200002,0x4000000,0x4000800,0x200000,0x4200800,0x802,0x200802,0x4200800,0x802,0x4000002,0x4200802,0x4200000,0x200800,0,0x2,0x4200802,0,0x200802,0x4200000,0x800,0x4000002,0x4000800,0x800,0x200002);
		$spfunction8 = array (0x10001040,0x1000,0x40000,0x10041040,0x10000000,0x10001040,0x40,0x10000000,0x40040,0x10040000,0x10041040,0x41000,0x10041000,0x41040,0x1000,0x40,0x10040000,0x10000040,0x10001000,0x1040,0x41000,0x40040,0x10040040,0x10041000,0x1040,0,0,0x10040040,0x10000040,0x10001000,0x41040,0x40000,0x41040,0x40000,0x10041000,0x1000,0x40,0x10040040,0x1000,0x41040,0x10001000,0x40,0x10000040,0x10040000,0x10040040,0x10000000,0x40000,0x10001040,0,0x10041040,0x40040,0x10000040,0x10040000,0x10001000,0x10001040,0,0x10041040,0x41000,0x41000,0x1040,0x1040,0x40040,0x10000000,0x10041000);
		$masks = array (4294967295,2147483647,1073741823,536870911,268435455,134217727,67108863,33554431,16777215,8388607,4194303,2097151,1048575,524287,262143,131071,65535,32767,16383,8191,4095,2047,1023,511,255,127,63,31,15,7,3,1,0);

		//create the 16 or 48 subkeys we will need
		$keys = self::des_createKeys($key);
		$m=0;
		$len = strlen($message);
		$chunk = 0;
		//set up the loops for single and triple des
		$iterations = ((count($keys) == 32) ? 3 : 9); //single or triple des
		if ($iterations == 3) {$looping = (($encrypt) ? array (0, 32, 2) : array (30, -2, -2));}
		else {$looping = (($encrypt) ? array (0, 32, 2, 62, 30, -2, 64, 96, 2) : array (94, 62, -2, 32, 64, 2, 30, -2, -2));}

		$message .= (chr(0) . chr(0) . chr(0) . chr(0) . chr(0) . chr(0) . chr(0) . chr(0)); //pad the message out with null bytes
		//store the result here
		$result = "";
		$tempresult = "";

		if ($mode == 1) { //CBC mode
			$cbcleft = (ord($iv{$m++}) << 24) | (ord($iv{$m++}) << 16) | (ord($iv{$m++}) << 8) | ord($iv{$m++});
			$cbcright = (ord($iv{$m++}) << 24) | (ord($iv{$m++}) << 16) | (ord($iv{$m++}) << 8) | ord($iv{$m++});
			$m=0;
		}

		//loop through each 64 bit chunk of the message
		while ($m < $len) {
			$left = (ord($message{$m++}) << 24) | (ord($message{$m++}) << 16) | (ord($message{$m++}) << 8) | ord($message{$m++});
			$right = (ord($message{$m++}) << 24) | (ord($message{$m++}) << 16) | (ord($message{$m++}) << 8) | ord($message{$m++});

			//for Cipher Block Chaining mode, xor the message with the previous result
			if ($mode == 1) {if ($encrypt) {$left ^= $cbcleft; $right ^= $cbcright;} else {$cbcleft2 = $cbcleft; $cbcright2 = $cbcright; $cbcleft = $left; $cbcright = $right;}}

			//first each 64 but chunk of the message must be permuted according to IP
			$temp = (($left >> 4 & $masks[4]) ^ $right) & 0x0f0f0f0f; $right ^= $temp; $left ^= ($temp << 4);
			$temp = (($left >> 16 & $masks[16]) ^ $right) & 0x0000ffff; $right ^= $temp; $left ^= ($temp << 16);
			$temp = (($right >> 2 & $masks[2]) ^ $left) & 0x33333333; $left ^= $temp; $right ^= ($temp << 2);
			$temp = (($right >> 8 & $masks[8]) ^ $left) & 0x00ff00ff; $left ^= $temp; $right ^= ($temp << 8);
			$temp = (($left >> 1 & $masks[1]) ^ $right) & 0x55555555; $right ^= $temp; $left ^= ($temp << 1);

			$left = (($left << 1) | ($left >> 31 & $masks[31])); 
			$right = (($right << 1) | ($right >> 31 & $masks[31])); 

			//do this either 1 or 3 times for each chunk of the message
			for ($j=0; $j<$iterations; $j+=3) {
				$endloop = $looping[$j+1];
				$loopinc = $looping[$j+2];
				//now go through and perform the encryption or decryption  
				for ($i=$looping[$j]; $i!=$endloop; $i+=$loopinc) { //for efficiency
					$right1 = $right ^ $keys[$i]; 
					$right2 = (($right >> 4 & $masks[4]) | ($right << 28)) ^ $keys[$i+1];
					//the result is attained by passing these bytes through the S selection functions
					$temp = $left;
					$left = $right;
					$right = $temp ^ ($spfunction2[($right1 >> 24 & $masks[24]) & 0x3f] | $spfunction4[($right1 >> 16 & $masks[16]) & 0x3f]
								| $spfunction6[($right1 >>  8 & $masks[8]) & 0x3f] | $spfunction8[$right1 & 0x3f]
								| $spfunction1[($right2 >> 24 & $masks[24]) & 0x3f] | $spfunction3[($right2 >> 16 & $masks[16]) & 0x3f]
								| $spfunction5[($right2 >>  8 & $masks[8]) & 0x3f] | $spfunction7[$right2 & 0x3f]);
				}
				$temp = $left; $left = $right; $right = $temp; //unreverse left and right
			} //for either 1 or 3 iterations

			//move then each one bit to the right
			$left = (($left >> 1 & $masks[1]) | ($left << 31)); 
			$right = (($right >> 1 & $masks[1]) | ($right << 31)); 

			//now perform IP-1, which is IP in the opposite direction
			$temp = (($left >> 1 & $masks[1]) ^ $right) & 0x55555555; $right ^= $temp; $left ^= ($temp << 1);
			$temp = (($right >> 8 & $masks[8]) ^ $left) & 0x00ff00ff; $left ^= $temp; $right ^= ($temp << 8);
			$temp = (($right >> 2 & $masks[2]) ^ $left) & 0x33333333; $left ^= $temp; $right ^= ($temp << 2);
			$temp = (($left >> 16 & $masks[16]) ^ $right) & 0x0000ffff; $right ^= $temp; $left ^= ($temp << 16);
			$temp = (($left >> 4 & $masks[4]) ^ $right) & 0x0f0f0f0f; $right ^= $temp; $left ^= ($temp << 4);

			//for Cipher Block Chaining mode, xor the message with the previous result
			if ($mode == 1) {if ($encrypt) {$cbcleft = $left; $cbcright = $right;} else {$left ^= $cbcleft2; $right ^= $cbcright2;}}
			$tempresult .= (chr($left>>24 & $masks[24]) . chr(($left>>16 & $masks[16]) & 0xff) . chr(($left>>8 & $masks[8]) & 0xff) . chr($left & 0xff) . chr($right>>24 & $masks[24]) . chr(($right>>16 & $masks[16]) & 0xff) . chr(($right>>8 & $masks[8]) & 0xff) . chr($right & 0xff));

			$chunk += 8;
			if ($chunk == 512) {$result .= $tempresult; $tempresult = ""; $chunk = 0;}
		} //for every 8 characters, or 64 bits in the message

		//return the result as an array
		return ($result . $tempresult);
	}

	/**
	 * des_createKeys
	 * this takes as input a 64 bit key (even though only 56 bits are used)
	 * as an array of 2 integers, and returns 16 48 bit keys
	 */
	public static function des_createKeys($key) {
		//declaring this locally speeds things up a bit
		$pc2bytes0  = array (0,0x4,0x20000000,0x20000004,0x10000,0x10004,0x20010000,0x20010004,0x200,0x204,0x20000200,0x20000204,0x10200,0x10204,0x20010200,0x20010204);
		$pc2bytes1  = array (0,0x1,0x100000,0x100001,0x4000000,0x4000001,0x4100000,0x4100001,0x100,0x101,0x100100,0x100101,0x4000100,0x4000101,0x4100100,0x4100101);
		$pc2bytes2  = array (0,0x8,0x800,0x808,0x1000000,0x1000008,0x1000800,0x1000808,0,0x8,0x800,0x808,0x1000000,0x1000008,0x1000800,0x1000808);
		$pc2bytes3  = array (0,0x200000,0x8000000,0x8200000,0x2000,0x202000,0x8002000,0x8202000,0x20000,0x220000,0x8020000,0x8220000,0x22000,0x222000,0x8022000,0x8222000);
		$pc2bytes4  = array (0,0x40000,0x10,0x40010,0,0x40000,0x10,0x40010,0x1000,0x41000,0x1010,0x41010,0x1000,0x41000,0x1010,0x41010);
		$pc2bytes5  = array (0,0x400,0x20,0x420,0,0x400,0x20,0x420,0x2000000,0x2000400,0x2000020,0x2000420,0x2000000,0x2000400,0x2000020,0x2000420);
		$pc2bytes6  = array (0,0x10000000,0x80000,0x10080000,0x2,0x10000002,0x80002,0x10080002,0,0x10000000,0x80000,0x10080000,0x2,0x10000002,0x80002,0x10080002);
		$pc2bytes7  = array (0,0x10000,0x800,0x10800,0x20000000,0x20010000,0x20000800,0x20010800,0x20000,0x30000,0x20800,0x30800,0x20020000,0x20030000,0x20020800,0x20030800);
		$pc2bytes8  = array (0,0x40000,0,0x40000,0x2,0x40002,0x2,0x40002,0x2000000,0x2040000,0x2000000,0x2040000,0x2000002,0x2040002,0x2000002,0x2040002);
		$pc2bytes9  = array (0,0x10000000,0x8,0x10000008,0,0x10000000,0x8,0x10000008,0x400,0x10000400,0x408,0x10000408,0x400,0x10000400,0x408,0x10000408);
		$pc2bytes10 = array (0,0x20,0,0x20,0x100000,0x100020,0x100000,0x100020,0x2000,0x2020,0x2000,0x2020,0x102000,0x102020,0x102000,0x102020);
		$pc2bytes11 = array (0,0x1000000,0x200,0x1000200,0x200000,0x1200000,0x200200,0x1200200,0x4000000,0x5000000,0x4000200,0x5000200,0x4200000,0x5200000,0x4200200,0x5200200);
		$pc2bytes12 = array (0,0x1000,0x8000000,0x8001000,0x80000,0x81000,0x8080000,0x8081000,0x10,0x1010,0x8000010,0x8001010,0x80010,0x81010,0x8080010,0x8081010);
		$pc2bytes13 = array (0,0x4,0x100,0x104,0,0x4,0x100,0x104,0x1,0x5,0x101,0x105,0x1,0x5,0x101,0x105);
		$masks = array (4294967295,2147483647,1073741823,536870911,268435455,134217727,67108863,33554431,16777215,8388607,4194303,2097151,1048575,524287,262143,131071,65535,32767,16383,8191,4095,2047,1023,511,255,127,63,31,15,7,3,1,0);

		//how many iterations (1 for des, 3 for triple des)
		$iterations = ((strlen($key) >= 24) ? 3 : 1);
		//stores the return keys
		$keys = array (); // size = 32 * iterations but you don't specify this in php
		//now define the left shifts which need to be done
		$shifts = array (0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0);
		//other variables
		$m=0;
		$n=0;

		for ($j=0; $j<$iterations; $j++) { //either 1 or 3 iterations
			$left = (ord($key{$m++}) << 24) | (ord($key{$m++}) << 16) | (ord($key{$m++}) << 8) | ord($key{$m++});
			$right = (ord($key{$m++}) << 24) | (ord($key{$m++}) << 16) | (ord($key{$m++}) << 8) | ord($key{$m++});

			$temp = (($left >> 4 & $masks[4]) ^ $right) & 0x0f0f0f0f; $right ^= $temp; $left ^= ($temp << 4);
			$temp = (($right >> 16 & $masks[16]) ^ $left) & 0x0000ffff; $left ^= $temp; $right ^= ($temp << -16);
			$temp = (($left >> 2 & $masks[2]) ^ $right) & 0x33333333; $right ^= $temp; $left ^= ($temp << 2);
			$temp = (($right >> 16 & $masks[16]) ^ $left) & 0x0000ffff; $left ^= $temp; $right ^= ($temp << -16);
			$temp = (($left >> 1 & $masks[1]) ^ $right) & 0x55555555; $right ^= $temp; $left ^= ($temp << 1);
			$temp = (($right >> 8 & $masks[8]) ^ $left) & 0x00ff00ff; $left ^= $temp; $right ^= ($temp << 8);
			$temp = (($left >> 1 & $masks[1]) ^ $right) & 0x55555555; $right ^= $temp; $left ^= ($temp << 1);

			//the right side needs to be shifted and to get the last four bits of the left side
			$temp = ($left << 8) | (($right >> 20 & $masks[20]) & 0x000000f0);
			//left needs to be put upside down
			$left = ($right << 24) | (($right << 8) & 0xff0000) | (($right >> 8 & $masks[8]) & 0xff00) | (($right >> 24 & $masks[24]) & 0xf0);
			$right = $temp;

			//now go through and perform these shifts on the left and right keys
			for ($i=0; $i < count($shifts); $i++) {
				//shift the keys either one or two bits to the left
				if ($shifts[$i] > 0) {
					 $left = (($left << 2) | ($left >> 26 & $masks[26]));
					 $right = (($right << 2) | ($right >> 26 & $masks[26]));
				} else {
					 $left = (($left << 1) | ($left >> 27 & $masks[27]));
					 $right = (($right << 1) | ($right >> 27 & $masks[27]));
				}
				$left = $left & -0xf;
				$right = $right & -0xf;

				//now apply PC-2, in such a way that E is easier when encrypting or decrypting
				//this conversion will look like PC-2 except only the last 6 bits of each byte are used
				//rather than 48 consecutive bits and the order of lines will be according to 
				//how the S selection functions will be applied: S2, S4, S6, S8, S1, S3, S5, S7
				$lefttemp = $pc2bytes0[$left >> 28 & $masks[28]] | $pc2bytes1[($left >> 24 & $masks[24]) & 0xf]
								| $pc2bytes2[($left >> 20 & $masks[20]) & 0xf] | $pc2bytes3[($left >> 16 & $masks[16]) & 0xf]
								| $pc2bytes4[($left >> 12 & $masks[12]) & 0xf] | $pc2bytes5[($left >> 8 & $masks[8]) & 0xf]
								| $pc2bytes6[($left >> 4 & $masks[4]) & 0xf];
				$righttemp = $pc2bytes7[$right >> 28 & $masks[28]] | $pc2bytes8[($right >> 24 & $masks[24]) & 0xf]
									| $pc2bytes9[($right >> 20 & $masks[20]) & 0xf] | $pc2bytes10[($right >> 16 & $masks[16]) & 0xf]
									| $pc2bytes11[($right >> 12 & $masks[12]) & 0xf] | $pc2bytes12[($right >> 8 & $masks[8]) & 0xf]
									| $pc2bytes13[($right >> 4 & $masks[4]) & 0xf];
				$temp = (($righttemp >> 16 & $masks[16]) ^ $lefttemp) & 0x0000ffff; 
				$keys[$n++] = $lefttemp ^ $temp; $keys[$n++] = $righttemp ^ ($temp << 16);
			}
		} //for each iterations
		//return the keys we've created
		return $keys;
	}

	/*
		function stringToHex ($s) {
			$r = "0x";
			$hexes = array ("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f");
			for ($i=0; $i<strlen($s); $i++) {$r .= ($hexes [(ord($s{$i}) >> 4)] . $hexes [(ord($s{$i}) & 0xf)]);}
			return $r;
		}
		echo "<PRE>";
		$key = "this is a 24 byte key !!";
		$message = "This is a test message";
		$ciphertext = des ($key, $message, 1, 0, null);
		echo "DES Test Encrypted: " . stringToHex ($ciphertext);
		$recovered_message = des ($key, $ciphertext, 0, 0, null);
		echo "\n";
		echo "DES Test Decrypted: " . $recovered_message;
	*/

}