[Cryptography] Simple key derivation function based on card shuffling

[Jacob Christian Munch-Andersen]

On Fri, Jul 23, 2021, at 6:56 PM, Leo wrote:
> I don't want to bother with depending on more traditional cryptographic hashes or sponges.
> Any opinions? Is this a valid method? Can anything useful be salvaged from this or is it hopeless?

What part of

import hashlib
hashlib.sha512(key).digest()

is a bother?

In any case, handling single bits like that is extremely inefficient. On top of that such a shuffling pattern is prone to short periods, depending on the key. In the worst case you loop right back to the starting pattern.

For reference, the code as I believe it is supposed to be indented: https://gist.github.com/NoHatCoder/c8d7c72825f8167a97fc9ec2ac711c3a
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