mcrypt加密与解密

$key = 'test';
$result_array = array('name' => 'ta', 'age' => 28);
$str = encode($result_array);

function encode($result_array) {
          global $key;//JSON_PRETTY_PRINT  JSON_UNESCAPED_UNICODE
         $result = json_encode($result_array, JSON_UNESCAPED_UNICODE);
        //$result = str_replace(":null", ':""', $result);

          $str = $result;

        $block = mcrypt_get_block_size('des', 'ecb');
        $pad = $block - (strlen($str) % $block);
        $str .= str_repeat(chr($pad), $pad); 

        $encode = base64_encode(mcrypt_encrypt(MCRYPT_DES, $key, $str, MCRYPT_MODE_ECB));
          return $encode;
}
//echo $str;exit;

function decode($str) {
     global $key;
     $encode = $str;
     $json = mcrypt_decrypt(MCRYPT_DES, $key, base64_decode($encode), MCRYPT_MODE_ECB);
     $block = mcrypt_get_block_size('des', 'ecb');
     $pad = ord($json[($len = strlen($json)) - 1]);
     $json = substr($json, 0, strlen($json) - $pad);

     return $json;
}

 function _encrypt($str)
    {
       global $key;
        $block = mcrypt_get_block_size('des', 'ecb');
        $pad = $block - (strlen($str) % $block);
        $str .= str_repeat(chr($pad), $pad); 

        return base64_encode(mcrypt_encrypt(MCRYPT_DES, $key, $str, MCRYPT_MODE_ECB));
    }