破碎的CRC32联合收割机

Question

事情是这样的，我一直在思考如何得到一个运算符，我可以使用，因为我也在使用一个非标准的CRC计算。最初的CRC计算是基于查找表的CRC32 0xEDB88320多项式，但是计算本身被破坏了，所以不是像0x00000000、0x77073096、0xEE0E612C、0x990951BA、0x076DC419、0x706AF48F、0xE963A535、...它现在看起来像这个0x00000000，0x960000，0x30960000，0x07309600，0x77073096，0x2C770730，0x612C7707，...并且组合CRC使用该运算符来使其馀的比特归零。

不幸的是，我不能改变计算，所以那个想法出来了：有什么想法吗？

编辑：

完整类代码

public static byte[] ByteLookupTable =
        {
        0x00,0x00,0x00,0x00,0x96,0x30,0x07,0x77,0x2C,0x61,0x0E,0xEE,0xBA,0x51,
        0x09,0x99,0x19,0xC4,0x6D,0x07,0x8F,0xF4,0x6A,0x70,0x35,0xA5,0x63,
        0xE9,0xA3,0x95,0x64,0x9E,0x32,0x88,0xDB,0x0E,0xA4,0xB8,0xDC,0x79,0x1E,
        0xE9,0xD5,0xE0,0x88,0xD9,0xD2,0x97,0x2B,0x4C,0xB6,0x09,0xBD,0x7C,
        0xB1,0x7E,0x07,0x2D,0xB8,0xE7,0x91,0x1D,0xBF,0x90,0x64,0x10,0xB7,0x1D,
        0xF2,0x20,0xB0,0x6A,0x48,0x71,0xB9,0xF3,0xDE,0x41,0xBE,0x84,0x7D,
        0xD4,0xDA,0x1A,0xEB,0xE4,0xDD,0x6D,0x51,0xB5,0xD4,0xF4,0xC7,0x85,0xD3,
        0x83,0x56,0x98,0x6C,0x13,0xC0,0xA8,0x6B,0x64,0x7A,0xF9,0x62,0xFD,
        0xEC,0xC9,0x65,0x8A,0x4F,0x5C,0x01,0x14,0xD9,0x6C,0x06,0x63,0x63,0x3D,
        0x0F,0xFA,0xF5,0x0D,0x08,0x8D,0xC8,0x20,0x6E,0x3B,0x5E,0x10,0x69,
        0x4C,0xE4,0x41,0x60,0xD5,0x72,0x71,0x67,0xA2,0xD1,0xE4,0x03,0x3C,0x47,
        0xD4,0x04,0x4B,0xFD,0x85,0x0D,0xD2,0x6B,0xB5,0x0A,0xA5,0xFA,0xA8,
        0xB5,0x35,0x6C,0x98,0xB2,0x42,0xD6,0xC9,0xBB,0xDB,0x40,0xF9,0xBC,0xAC,
        0xE3,0x6C,0xD8,0x32,0x75,0x5C,0xDF,0x45,0xCF,0x0D,0xD6,0xDC,0x59,
        0x3D,0xD1,0xAB,0xAC,0x30,0xD9,0x26,0x3A,0x00,0xDE,0x51,0x80,0x51,0xD7,
        0xC8,0x16,0x61,0xD0,0xBF,0xB5,0xF4,0xB4,0x21,0x23,0xC4,0xB3,0x56,
        0x99,0x95,0xBA,0xCF,0x0F,0xA5,0xBD,0xB8,0x9E,0xB8,0x02,0x28,0x08,0x88,
        0x05,0x5F,0xB2,0xD9,0x0C,0xC6,0x24,0xE9,0x0B,0xB1,0x87,0x7C,0x6F,
        0x2F,0x11,0x4C,0x68,0x58,0xAB,0x1D,0x61,0xC1,0x3D,0x2D,0x66,0xB6,0x90,
        0x41,0xDC,0x76,0x06,0x71,0xDB,0x01,0xBC,0x20,0xD2,0x98,0x2A,0x10,
        0xD5,0xEF,0x89,0x85,0xB1,0x71,0x1F,0xB5,0xB6,0x06,0xA5,0xE4,0xBF,0x9F,
        0x33,0xD4,0xB8,0xE8,0xA2,0xC9,0x07,0x78,0x34,0xF9,0x00,0x0F,0x8E,
        0xA8,0x09,0x96,0x18,0x98,0x0E,0xE1,0xBB,0x0D,0x6A,0x7F,0x2D,0x3D,0x6D,
        0x08,0x97,0x6C,0x64,0x91,0x01,0x5C,0x63,0xE6,0xF4,0x51,0x6B,0x6B,
        0x62,0x61,0x6C,0x1C,0xD8,0x30,0x65,0x85,0x4E,0x00,0x62,0xF2,0xED,0x95,
        0x06,0x6C,0x7B,0xA5,0x01,0x1B,0xC1,0xF4,0x08,0x82,0x57,0xC4,0x0F,
        0xF5,0xC6,0xD9,0xB0,0x65,0x50,0xE9,0xB7,0x12,0xEA,0xB8,0xBE,0x8B,0x7C,
        0x88,0xB9,0xFC,0xDF,0x1D,0xDD,0x62,0x49,0x2D,0xDA,0x15,0xF3,0x7C,
        0xD3,0x8C,0x65,0x4C,0xD4,0xFB,0x58,0x61,0xB2,0x4D,0xCE,0x51,0xB5,0x3A,
        0x74,0x00,0xBC,0xA3,0xE2,0x30,0xBB,0xD4,0x41,0xA5,0xDF,0x4A,0xD7,
        0x95,0xD8,0x3D,0x6D,0xC4,0xD1,0xA4,0xFB,0xF4,0xD6,0xD3,0x6A,0xE9,0x69,
        0x43,0xFC,0xD9,0x6E,0x34,0x46,0x88,0x67,0xAD,0xD0,0xB8,0x60,0xDA,
        0x73,0x2D,0x04,0x44,0xE5,0x1D,0x03,0x33,0x5F,0x4C,0x0A,0xAA,0xC9,0x7C,
        0x0D,0xDD,0x3C,0x71,0x05,0x50,0xAA,0x41,0x02,0x27,0x10,0x10,0x0B,
        0xBE,0x86,0x20,0x0C,0xC9,0x25,0xB5,0x68,0x57,0xB3,0x85,0x6F,0x20,0x09,
        0xD4,0x66,0xB9,0x9F,0xE4,0x61,0xCE,0x0E,0xF9,0xDE,0x5E,0x98,0xC9,
        0xD9,0x29,0x22,0x98,0xD0,0xB0,0xB4,0xA8,0xD7,0xC7,0x17,0x3D,0xB3,0x59,
        0x81,0x0D,0xB4,0x2E,0x3B,0x5C,0xBD,0xB7,0xAD,0x6C,0xBA,0xC0,0x20,
        0x83,0xB8,0xED,0xB6,0xB3,0xBF,0x9A,0x0C,0xE2,0xB6,0x03,0x9A,0xD2,0xB1,
        0x74,0x39,0x47,0xD5,0xEA,0xAF,0x77,0xD2,0x9D,0x15,0x26,0xDB,0x04,
        0x83,0x16,0xDC,0x73,0x12,0x0B,0x63,0xE3,0x84,0x3B,0x64,0x94,0x3E,0x6A,
        0x6D,0x0D,0xA8,0x5A,0x6A,0x7A,0x0B,0xCF,0x0E,0xE4,0x9D,0xFF,0x09,
        0x93,0x27,0xAE,0x00,0x0A,0xB1,0x9E,0x07,0x7D,0x44,0x93,0x0F,0xF0,0xD2,
        0xA3,0x08,0x87,0x68,0xF2,0x01,0x1E,0xFE,0xC2,0x06,0x69,0x5D,0x57,
        0x62,0xF7,0xCB,0x67,0x65,0x80,0x71,0x36,0x6C,0x19,0xE7,0x06,0x6B,0x6E,
        0x76,0x1B,0xD4,0xFE,0xE0,0x2B,0xD3,0x89,0x5A,0x7A,0xDA,0x10,0xCC,
        0x4A,0xDD,0x67,0x6F,0xDF,0xB9,0xF9,0xF9,0xEF,0xBE,0x8E,0x43,0xBE,0xB7,
        0x17,0xD5,0x8E,0xB0,0x60,0xE8,0xA3,0xD6,0xD6,0x7E,0x93,0xD1,0xA1,
        0xC4,0xC2,0xD8,0x38,0x52,0xF2,0xDF,0x4F,0xF1,0x67,0xBB,0xD1,0x67,0x57,
        0xBC,0xA6,0xDD,0x06,0xB5,0x3F,0x4B,0x36,0xB2,0x48,0xDA,0x2B,0x0D,
        0xD8,0x4C,0x1B,0x0A,0xAF,0xF6,0x4A,0x03,0x36,0x60,0x7A,0x04,0x41,0xC3,
        0xEF,0x60,0xDF,0x55,0xDF,0x67,0xA8,0xEF,0x8E,0x6E,0x31,0x79,0xBE,
        0x69,0x46,0x8C,0xB3,0x61,0xCB,0x1A,0x83,0x66,0xBC,0xA0,0xD2,0x6F,0x25,
        0x36,0xE2,0x68,0x52,0x95,0x77,0x0C,0xCC,0x03,0x47,0x0B,0xBB,0xB9,
        0x16,0x02,0x22,0x2F,0x26,0x05,0x55,0xBE,0x3B,0xBA,0xC5,0x28,0x0B,0xBD,
        0xB2,0x92,0x5A,0xB4,0x2B,0x04,0x6A,0xB3,0x5C,0xA7,0xFF,0xD7,0xC2,
        0x31,0xCF,0xD0,0xB5,0x8B,0x9E,0xD9,0x2C,0x1D,0xAE,0xDE,0x5B,0xB0,0xC2,
        0x64,0x9B,0x26,0xF2,0x63,0xEC,0x9C,0xA3,0x6A,0x75,0x0A,0x93,0x6D,
        0x02,0xA9,0x06,0x09,0x9C,0x3F,0x36,0x0E,0xEB,0x85,0x67,0x07,0x72,0x13,
        0x57,0x00,0x05,0x82,0x4A,0xBF,0x95,0x14,0x7A,0xB8,0xE2,0xAE,0x2B,
        0xB1,0x7B,0x38,0x1B,0xB6,0x0C,0x9B,0x8E,0xD2,0x92,0x0D,0xBE,0xD5,0xE5,
        0xB7,0xEF,0xDC,0x7C,0x21,0xDF,0xDB,0x0B,0xD4,0xD2,0xD3,0x86,0x42,
        0xE2,0xD4,0xF1,0xF8,0xB3,0xDD,0x68,0x6E,0x83,0xDA,0x1F,0xCD,0x16,0xBE,
        0x81,0x5B,0x26,0xB9,0xF6,0xE1,0x77,0xB0,0x6F,0x77,0x47,0xB7,0x18,
        0xE6,0x5A,0x08,0x88,0x70,0x6A,0x0F,0xFF,0xCA,0x3B,0x06,0x66,0x5C,0x0B,
        0x01,0x11,0xFF,0x9E,0x65,0x8F,0x69,0xAE,0x62,0xF8,0xD3,0xFF,0x6B,
        0x61,0x45,0xCF,0x6C,0x16,0x78,0xE2,0x0A,0xA0,0xEE,0xD2,0x0D,0xD7,0x54,
        0x83,0x04,0x4E,0xC2,0xB3,0x03,0x39,0x61,0x26,0x67,0xA7,0xF7,0x16,
        0x60,0xD0,0x4D,0x47,0x69,0x49,0xDB,0x77,0x6E,0x3E,0x4A,0x6A,0xD1,0xAE,
        0xDC,0x5A,0xD6,0xD9,0x66,0x0B,0xDF,0x40,0xF0,0x3B,0xD8,0x37,0x53,
        0xAE,0xBC,0xA9,0xC5,0x9E,0xBB,0xDE,0x7F,0xCF,0xB2,0x47,0xE9,0xFF,0xB5,
        0x30,0x1C,0xF2,0xBD,0xBD,0x8A,0xC2,0xBA,0xCA,0x30,0x93,0xB3,0x53,
        0xA6,0xA3,0xB4,0x24,0x05,0x36,0xD0,0xBA,0x93,0x06,0xD7,0xCD,0x29,0x57,
        0xDE,0x54,0xBF,0x67,0xD9,0x23,0x2E,0x7A,0x66,0xB3,0xB8,0x4A,0x61,
        0xC4,0x02,0x1B,0x68,0x5D,0x94,0x2B,0x6F,0x2A,0x37,0xBE,0x0B,0xB4,0xA1,
        0x8E,0x0C,0xC3,0x1B,0xDF,0x05,0x5A,0x8D,0xEF,0x02,0x2D,0xC3,0x8D,0x40,0x00
        };

    protected void BuildLookupTable()
    {
        if (LookupTable == null)
        {
            LookupTable = new uint[256];
            for (int i = 0; i < LookupTable.Length; i++)
            {
                LookupTable[i] = BitConverter.ToUInt32(ByteLookupTable, i);
            }
        }
    }

    protected override uint CalculateBuffer(byte[] buffer, uint crc, int startPos, int endPos)
    {
        for (int i = 0; i < endPos; i++)
        {
            crc = LookupTable[(crc ^ buffer[i]) & 0xff] ^ (crc >> 8);
        }
        return crc;
    }

Answer 1

对于该多项式，查找表常量是正确的，但显然buildlookuptable()所做的转换完全搞砸了。重写表以避免需要buildlookuptable()是很容易的。

下面的内容来自原始答案，该答案假定表转换正确。但事实并非如此。

事实上，这不是CRC，所以CRC的组合方法不适用于这里。