PHP mcrypt加密解密

需要安装php的mcrypt的扩展    class AMPCrypt {      private static function getKey(){          return md5('exampleKey');      }        public static function encrypt($value){           $td = mcrypt_module_open('tripledes', '', 'ecb', '');           $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_DEV_RANDOM);           $key = substr(self::getKey(), 0, mcrypt_enc_get_key_size($td));           mcrypt_generic_init($td, $key, $iv);           $ret = base64_encode(mcrypt_generic($td, $value));           mcrypt_generic_deinit($td);           mcrypt_module_close($td);           return $ret;      }        public static function dencrypt($value){           $td = mcrypt_module_open('tripledes', '', 'ecb', '');           $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_DEV_RANDOM);           $key = substr(self::getKey(), 0, mcrypt_enc_get_key_size($td));           $key = substr(self::getKey(), 0, mcrypt_enc_get_key_size($td));           mcrypt_generic_init($td, $key, $iv);           $ret = trim(mdecrypt_generic($td, base64_decode($value))) ;           mcrypt_generic_deinit($td);           mcrypt_module_close($td);          return $ret;       }  }