file - CRC32真的对文件完整性检查不好吗？

Question

当然，MD5比CRC32更好，SHA1比MD5更好，依此类推...但是它们也比CRC32慢得多。

正确的知道，我正在考虑如何检查正在传输的文件的一致性，而CRC32是最快的选择。

我在任何地方都没有发现 CRC32对完整性检查有多严重(也许换句话说，CRC32不会检测格式错误的文件)？

Answer 1

引用http://www.mathpages.com/home/kmath458.htm:

So, if we assume that any corruption of our data affects our string in a completely random way, i.e., such that the corrupted string is totally uncorrelated with the original string, then the probability of a corrupted string going undetected is 1/(2^n). This is the basis on which people say a 16-bit CRC has a probability of 1/(2^16) = 1.5E-5 of failing to detect an error in the data, and a 32-bit CRC has a probability of 1/(2^32), which is about 2.3E-10 (less than one in a billion).

我的看法:CRC-32足以检测错误。它被广泛使用。但是，当您要将其用作“哈希函数”时，它并不安全。