Re: Stream ciphers

On Dec 29, 11:42 pm, Ivan Voras <ivo...@xxxxxxxxx> wrote:
I am thinking about big flipping and key / keystream reuse.

You must NEVER reuse the key. This is usually acomplished by dividing
the "whole key" in two parts:
The master key (called simply key) and the nonce. The master key may
stay the same and must be kept secret, the nonce may never repeat and
may be implemented simply as a counter. For example, Salsa20 uses a
256 bit key and 64 bit nonce.

Mixing the plaintext into the internal state could help a bit in case
of repeating the "whole key", but it always leaks some information. At
least with two ciphertexts c1 and c2, which happen to be equal, you
know the plaintexts are equal too.

My question: What are the most interesting stream ciphers working not
by simple xoring?

.

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