我必须找出如何重现专有数据库文件上使用的CRC32算法，该文件由许多128字节的“块”组成，每个块都是一个记录。我知道对于每个记录，字节1-4是CRC32校验和，接下来的35个字节似乎并不重要，因为我可以轻松地更改它们而不会让应用程序告诉我CRC校验失败。因此，我希望找出用于计算后者的多项式和其他参数。以下是一个例子。
文字版：
00 27 AE 3B 9F 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 41 08 41 41 41 41 41 41 41 41
19 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42
42 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00
如果我们只采用我们无法改变的字节，打破记录，我们得到：
41 08 41 41 41 41 41 41 41 41 19 42 42 42 42 42 42 42 42 42 42 42 42 42 42
42 42 42 42 42 42 42 42 42 42 42 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00
以上的CRC32是27 AE 3B 9F
实际记录示例1.1，与上面仅相差一个字节（CRC是BC D4 84 FB）：
41 08 41 41 41 41 41 41 41 41 19 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42
42 42 42 42 42 42 42 42 42 43 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00
实记录示例2（输出CRC为3B 6A D1 AF）：
41 07 41 41 41 41 41 41 41 00 19 42 42 42 42 42 42 42 42 42 42 42 42 42 42 42
42 42 42 42 42 42 42 42 42 42 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00
实记录示例3（输出CRC为0B 54 CC 09）：
41 01 31 00 00 00 00 00 00 00 03 41 73 61 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00
实际记录示例4（输出CRC为12 91 EA 8E）：
41 B4 A8 D0 02 46 00 B4 A8 00 03 52 4D 31 03 53 54 50 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 25 00 00 00 00 00 00 00
00 00 A3 05 00 00 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64
00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
实记录例5（输出CRC为8A 68 00 3B）：
41 B4 A8 D0 02 46 00 B4 A8 01 03 52 4D 31 03 53 54 50 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 FF 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 25 00 00 00 00 00 00 00
00 00 A3 05 00 00 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64
00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 64 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
最后两个记录仅在一个字节上有所不同。通过使用指定的方法@rcgldr，我能够获得最终的Xor值0x9902539d，并且我可以在没有应用程序抱怨的情况下成功更改数据。我运行了一些代码来为应用程序上的每个授权/文件找到这些最终的xor值，并且在所有这些值上都是成功的，但是能够找到单个crc参数集将是一个很好的补充。
编辑：添加了两个示例记录
编辑2：添加了另一个例子，与第一个字节相比，只有一个字节不同
编辑3：添加了两个不同大小的示例，作为应用程序中其他类型记录的示例。也删除了部分问题，因为它变得无关紧要
xor'ing 1.0和1.1导致：
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00
xor'ing这两个crcs导致
9b 7a bf 64
假设存储的crc为“小端”，计算的crc为
0x64bf7a9b
通过xor'ing两个记录，初始值和最终xor值由于xor而被抵消，这允许基于单独的数据确定crc多项式，假设初始值= 0并且最终xor值= 0。利用这一点，我尝试了一些常见的crc多项式并确定了crc多项式
0x104C11DB7 or ignoring the msb: 0x04C11DB7
使用您在评论中链接到的网站：
http://www.sunshine2k.de/coding/javascript/crc/crc_js.html
参数是：
crc32
custom
input: not reflected
result: not reflected
polynomial: 0x04C11DB7
initial value: 0x0
final xor value: 0x0
如果数据总是大小相同，则可以使用初始值或最终xor值或两者的组合来调整crc，使其与示例中显示的实际crc相匹配，但最简单的方法是使用final xor以匹配示例，因为它只需要使用其中一个示例计算crc，假设初始值= 0且最终xor值= 0，然后将计算出的crc与示例crc中的实际crc进行xor计算得出特定长度数据的最终xor值。
因此，对于第一个示例中的数据大小，最终xor值0x189B52BC将生成与示例匹配的crc。这些是crc计算器的参数。
crc32
custom
input: not reflected
result: not reflected
polynomial: 0x04C11DB7
initial value: 0x0
final xor value: 0x189B52BC
这些参数与您发布的所有第一个示例相匹配。再次注意，crc存储为“little endian”，最重要的是字节。
如果数据大小是可变的，则需要初始值（并且可能使用初始值和最终xor值）。一旦知道多项式，就可以进行“反向”CRC以找到初始值，或者可以使用强力搜索。我使用快速crc计算器进行了蛮力搜索初始值（因为我还没有“反向”CRC程序），并且它似乎适用于任何数据大小，至少基于新的示例你补充说。这些参数适用于上面的所有示例，包括您添加的新示例：
crc32
custom
input: not reflected
result: not reflected
polynomial: 0x04C11DB7
initial value: 0xc704dd7b
final xor value: 0x0
0xc704dd7b的初始值是使用{ff ff ff ff}的数据模式生成的crc，初始值= 0且最终xor值= 0.这与使用{ff ff ff ff}为数据添加前缀相同。