Prpcrypt::decrypt PHP Method

    public function decrypt($encrypted, $appid)
    {
        try {
            //使用BASE64对需要解密的字符串进行解码
            $ciphertext_dec = base64_decode($encrypted);
            $module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');
            $iv = substr($this->key, 0, 16);
            mcrypt_generic_init($module, $this->key, $iv);
            //解密
            $decrypted = mdecrypt_generic($module, $ciphertext_dec);
            mcrypt_generic_deinit($module);
            mcrypt_module_close($module);
        } catch (Exception $e) {
            return array(ErrorCode::$DecryptAESError, null);
        }
        try {
            //去除补位字符
            $pkc_encoder = new PKCS7Encoder();
            $result = $pkc_encoder->decode($decrypted);
            //去除16位随机字符串,网络字节序和AppId
            if (strlen($result) < 16) {
                return "";
            }
            $content = substr($result, 16, strlen($result));
            $len_list = unpack("N", substr($content, 0, 4));
            $xml_len = $len_list[1];
            $xml_content = substr($content, 4, $xml_len);
            $from_appid = substr($content, $xml_len + 4);
        } catch (Exception $e) {
            //print $e;
            return array(ErrorCode::$IllegalBuffer, null);
        }
        if ($from_appid != $appid) {
            return array(ErrorCode::$ValidateAppidError, null);
        }
        return array(0, $xml_content);
    }

	public function decrypt($msgSignature, $timestamp = null, $nonce, $postData, &$msg)
	{
		if (strlen($this->encodingAesKey) != 43) {
			return ErrorCode::$IllegalAesKey;
		}
		if ($timestamp == null) $timestamp = time();

		$pc = new Prpcrypt($this->encodingAesKey);

		$encrypt = simplexml_load_string($postData, 'SimpleXMLElement', LIBXML_NOCDATA);
		$encrypt = $encrypt->Encrypt;

		$sha1 = new SHA1;
		$array = $sha1->getSHA1($this->token, $timestamp, $nonce, $encrypt);
		$ret = $array[0];

		if ($ret != 0) {
			return $ret;
		}

		$signature = $array[1];
		if ($signature != $msgSignature) {
			return ErrorCode::$ValidateSignatureError;
		}

		$result = $pc->decrypt($encrypt, $this->appId);
		if ($result[0] != 0) {
			return $result[0];
		}
		$msg = $result[1];

		return ErrorCode::$OK;
	}