Refer to the PHP encryption and decryption processing class written by discuz's passport

/*----------------------------------------- -
= Copyright Agreement:
= GPL (The GNU GENERAL PUBLIC LICENSE Version 2, June 1991)
=--------------------------- ----------------------------------
= File name: cls.sys_crypt.php
= Summary: php encryption and decryption Processing class
= Version: 1.0
= Reference: Discuz forum’s passport related functions
=---------------------------------- --------------------------------
= Script Written By PHPWMS project team
= Last updated: xinge
= Last date: 2007- 12-09
---------------------------------------------=*/

class SysCrypt {
private $crypt_key;

//Constructor
public function __construct($crypt_key) {
 $this -> crypt_key = $crypt_key;
}

public function php_encrypt($txt) {
 srand((double) microtime() * 1000000);
 $encrypt_key = md5(rand(0,32000));
 $ctr = 0;
 $tmp = '';
 for($i = 0;$i $ctr = $ctr == strlen($encrypt_key) ? 0 : $ctr;
 $tmp .= $encrypt_key[$ctr].($txt[$i]^$encrypt_key[$ctr++] );
 }
 return base64_encode(self::__key($tmp,$this -> crypt_key));
}

public function php_decrypt($txt) {
 $txt = self::__key(base64_decode($txt ),$this -> crypt_key);
 $tmp = '';
 for($i = 0;$i < strlen($txt); $i++) {
 $md5 = $txt[$i];
 $tmp .= $txt[++$i] ^ $md5;
 }
 return $tmp;
}

private function __key($txt,$encrypt_key) {
 $encrypt_key = md5($encrypt_key);
 $ctr = 0;
 $tmp = '';
 for($i = 0; $i < strlen($txt); $i++) {
 $ctr = $ctr == strlen($encrypt_key) ? 0 : $ctr;
 $tmp .= $txt[$i] ^ $encrypt_key[$ctr++];
 }
 return $tmp;
}

public function __destruct() {
 $this -> crypt_key = null;
 }
}

#--Call example
$sc = new SysCrypt('phpwms');
$text = '110';
print($sc -> php_encrypt($text));
print('< ;br>');
print($sc -> php_decrypt($sc -> php_encrypt($text)));
?>