The statistical method you describe to determine the likelihood that a stream of bytes is "corrupted" (i.e., altered in some way from its original state) will only work for a very specific kind of corruption:  the kind that results in the assumed randomness of the bytes (due to encryption) being measurably reduced. If this is exactly the kind of corruption you expect and want to identify when it occurs, and you don't expect or want to identify any other kind of corruption, then the statistical method you describe may be useful to you.

Let's say you have an encrypted file that consists of 1,234,567,890 bytes. One arbitrary bit of one arbitrary byte is switched from 0 to 1, or vice versa. The file is now "corrupted" (i.e., altered from its original state). You will never discover this corruption after the fact by any statistical method (guesswork).

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