[Cryptography] Summary: compression before encryption

Nemo nemo at self-evident.org
Tue Jan 13 17:23:52 EST 2015

Nice summary, with one nitpick...

Stephan Neuhaus <stephan.neuhaus at zhaw.ch> writes:

> Another respondent (albert at puigsech.com) argued that
> Encrypt-then-Compress was also an option ("has its pros")

Compression after encryption is nonsense. Under any modern definition of
"secure", a secure cipher's output is computationally indistinguishable
from random noise, which is not compressible.

Put another way, to compress the long-run output of a cipher is to break
it, by definition.

Excellent summary otherwise.

 - Nemo

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