Compression of random binary data

[Gregory Ewing]

Steve D'Aprano wrote:
> - Encrypted data looks very much like random noise.

There's actually a practical use for that idea. If you can feed
the output of an encryption algorithm through a compressor and
make it smaller, it means there is a cryptographic weakness
in the algorithm that could potentially be exploited. Good
encryption algorithms produce output that looks almost completely
random to anyone who doesn't know how to decrypt it.

-- 
Greg