某cocos2djs游戏jsc以及资源文件解密

int deEncryptPng(
        const unsigned char *inputData,  // 本地读取的加密PNG数据（不含PNG头和IEND）
        size_t inputLen,                 // inputData长度
        const char *key,                 // 异或密钥字符串
        unsigned char *outputData        // 输出的完整解密PNG数据
)
{
    // 计算密钥长度
    size_t keyLen = strlen(key);

    // 总输出长度 = 输入长度 + 8字节PNG头 + 12字节IEND = inputLen + 20
    size_t outputLen = inputLen + 20;

    // 写入PNG标准头部：89 50 4E 47 0D 0A 1A 0A
    // (标准PNG文件头)
    outputData[0] = 0x89;
    outputData[1] = 0x50;
    outputData[2] = 0x4E;
    outputData[3] = 0x47;
    outputData[4] = 0x0D;
    outputData[5] = 0x0A;
    outputData[6] = 0x1A;
    outputData[7] = 0x0A;

    // 将输入数据拷贝到outputData的第8字节开始的位置
    memcpy(outputData + 8, inputData, inputLen);

    // 写入IEND块到尾部
    // IEND块共12字节：00 00 00 00 49 45 4E 44 AE 42 60 82
    size_t endPos = outputLen - 12;
    outputData[endPos + 0]  = 0x00;
    outputData[endPos + 1]  = 0x00;
    outputData[endPos + 2]  = 0x00;
    outputData[endPos + 3]  = 0x00;
    outputData[endPos + 4]  = 0x49; // 'I'
    outputData[endPos + 5]  = 0x45; // 'E'
    outputData[endPos + 6]  = 0x4E; // 'N'
    outputData[endPos + 7]  = 0x44; // 'D'
    outputData[endPos + 8]  = 0xAE;
    outputData[endPos + 9]  = 0x42;
    outputData[endPos + 10] = 0x60;
    outputData[endPos + 11] = 0x82;

    // 异或处理区域：从offset=8一直到(outputLen - 13)字节位置
    // 这对应原代码中v8 = a4 - 13的逻辑
    if (outputLen > 20) {
        size_t start = 8;
        size_t stop = outputLen - 13; // 包含此位置
        size_t idx = 0;
        for (size_t i = start; i <= stop; i++) {
            if (idx >= keyLen) idx = 0;
            outputData[i] ^= (unsigned char)key[idx++];
        }
    }

    // 返回密钥长度（根据原函数返回值逻辑）
    return (int)keyLen;
}

def export_data(
    jsc_file_path: str, encryption_key_str: str, output_file_path: str
) -> Optional[tuple]:
    """
    Function for decrypting JSC files
    """
    logger.info("Starting export_data...")

    code, status = check_file(jsc_file_path, ".JSC", True)
    if code != "OK":
        return code, status

    jsc_file = open(jsc_file_path, "rb")
    jsc_file_data = jsc_file.read()
    jsc_file.close()

    logger.info(f"Decrypting with key = {encryption_key_str}")
    output_data = xxtea.decrypt(jsc_file_data, encryption_key_str, padding=False)
    if len(output_data) == 0:
        return "WRONG_KEY", "Invalid encryption key!"

    is_gzip_file = True
    try:
        output_data = zlib.decompress(output_data, 32 + 15)
        logger.info("IT IS a GZIP archive.")
    except zlib.error as error:
        logger.info("It's NOT a GZIP archive.")
        is_gzip_file = False

    if not is_gzip_file:
        try:
            zip_file = io.BytesIO(output_data)
            ZipFile(zip_file)
            output_file_path += ".zip"
            logger.info("IT IS a ZIP archive.")
        except BadZipFile as error:
            logger.info("It is NOT a ZIP archive.")

    js_file = open(output_file_path, "wb")
    js_file.write(output_data)

    js_file.close()
    logger.info(f"File exported: {output_file_path}")
    return "OK", ""