我一直在尝试对crc32校验和进行逆向工程。我无法访问原始的J＃代码，因为它已编译并反编译它没有帮助。我通过reveng运行了10个有效负载，返回：
width = 32 poly = 0x04c11db7 init = 0xFFFFFFFF refin = false refout = false xorout = 0x00000000 check = 0x0376e6e7 name =“CRC-32 / MPEG-2”
我尝试通过两个不同的python库运行包，甚至构建了一个objective-c算法来尝试获取已知的校验和。重新创建都相互匹配，但它们与原始校验和不匹配。有什么想法吗？
以下是原始和计算的crc32校验和：
original -> calculated
1. 0x99c93052 -> 0x13bc2c5c
2. 0xb5cea403 -> 0x1fd00c8e
3. 0xc7e4f40c -> 0xf9698bd6
4. 0xabe5ad28 -> 0x6be300d6
5. 0x2dacbf16 -> 0x43b2c356
6. 0xf321c2E9 -> 0xacb5981a
7. 0x01430cb6 -> 0x2f9e64ee
8. 0xa1028afb -> 0x44c7182b
9. 0xe73118e6 -> 0xd6c1ffa5
10. 0x5f366305 -> 0x84961d17
赞赏任何和所有建议！
修改
根据请求，这里是原始有效载荷及其CRC-32 / MPEG-2校验和及其计算的校验和：
1. Payload = d3b09900005500005469746c653a090954657374207469746c652020202020202020202020202020202020202020202020202020202020200a4172746973743a09095465737420617274697374202020202020202020202020202020202020200a43443a0909095465737420434420202020202020202020202020202020202020202020200a4c6162656c3a0954657374204c626c202000
Orig = 0xf9297a54
Calc = 0xebcc0d91
2. Payload = d3b09900004300005469746c653a090954657374207469746c652032202020202020202020202020202020202020202020202020202020200a4172746973743a09095465737420617274697374202020202020202020202020202020202020200a43443a0909095465737420434420202020202020202020202020202020202020202020200a4c6162656c3a0954657374204c626c202000
Orig = 0xb518dad0
Calc = 0x45e4e895
3. Payload = d3b09900004300005469746c653a090954657374207469746c652033202020202020202020202020202020202020202020202020202020200a4172746973743a09095465737420617274697374202020202020202020202020202020202020200a43443a0909095465737420434420202020202020202020202020202020202020202020200a4c6162656c3a0954657374204c626c202000
Orig = 0xe367073b
Calc = 0x5db5800c
4. Payload = d3b09900004300005469746c653a090954657374207469746c652034202020202020202020202020202020202020202020202020202020200a4172746973743a09095465737420617274697374202020202020202020202020202020202020200a43443a0909095465737420434420202020202020202020202020202020202020202020200a4c6162656c3a0954657374204c626c202000
Orig = 0x44d90b1d
Calc = 0x14039bc3
这是我计算这些校验和的一种方法（尽管pycrc和我实现的Objective-c代码都给出了相同的结果）：
>>> import crcmod.predefined
>>> s = 'd3b09900004300005469746c653a090954657374207469746c652034202020202020202020202020202020202020202020202020202020200a4172746973743a09095465737420617274697374202020202020202020202020202020202020200a43443a0909095465737420434420202020202020202020202020202020202020202020200a4c6162656c3a0954657374204c626c202000'
>>> crc32_func = crcmod.predefined.mkCrcFun('crc-32-mpeg')
>>> print hex(crc32_func(s))
0x14039bc3
上面的代码使用了有效负载示例4.如您所见，计算出的校验和（0x14039bc3）与有效负载附带的原始校验和（0x44d90b1d）不匹配。
答案 0 :(得分：0)
所以事实证明只是传递十六进制作为一个字符串不会通过python库crcmod.得到正确的校验和它也不会采用bytearray，这似乎是一个更可能的方式计算准确的校验和。您需要做的是将bytearray作为缓冲区传递，然后计算正确的校验和。
使用问题中的示例：
>>> import crcmod.predefined
>>> s = 'd3b09900004300005469746c653a090954657374207469746c652034202020202020202020202020202020202020202020202020202020200a4172746973743a09095465737420617274697374202020202020202020202020202020202020200a43443a0909095465737420434420202020202020202020202020202020202020202020200a4c6162656c3a0954657374204c626c202000'
>>> h = s.decode("hex")
>>> b = bytearray(h)
>>> crc32_func = crcmod.predefined.mkCrcFun('crc-32-mpeg')
>>> print hex(crc32_func(buffer(b)))
0x44d90b1d
所以你有它。主要是我不知道如何计算CRC校验和的计算方法。希望这最终会帮助别人。