Quor's cipher

[Anonymous]

Matthew Ghio wrote:

> Antonomasia <ant at notatla.demon.co.uk> wrote:
>
> > How are you planning to detect which bytes are passed in this way ?
> > Chosen plaintext attacks would do it, and show where (a+b)^(a0+b0) == 0.
> > Looks like you've just doubled our progress.
>
> It doesn't take chosen plaintext, just known plaintext.

Even in the case where this doesn't work, you can simply collect all
128 plaintext/ciphertext pairs for the first byte (if you can get
enough known plaintexts)