<?php     class SysCrypt {     private $crypt_key;     // 构造函数  public function __construct($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;$i<strlen($txt);$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;  }  }        $sc = new SysCrypt('phpwms');  $text = '110';  print($sc -> php_encrypt($text));  print('<br>');  print($sc -> php_decrypt($sc -> php_encrypt($text)));  ?>