Graphical decrypt --- Introduction ---

Warning. This exercise is probably very hard even prohibitive for those who don't know primitive polynomials over finite fields! In this case please prefer Decrypt which is mathematically much more rudimentary.

Graphical decrypt is an exercise on the algebraic cryptology based on pseudo-random sequences generated by primitive polynomials over a finite field FFq. You will be presented a picture composed of n×n pixels, crypted by such a sequence. This picture has q colors, each color representing an element of FFq.

And your goal is to decrypt this crypted picture, by finding back the primitive polynomial as well as the starting terms which determine the pseudo-random sequence.

Now with q = and difficulty level = .

One should remark however that this is just an exercise for teaching purposes. Even with the highest difficulty level, it is still incomparably easier than the real algebraic crypting in the real life... The most recent version

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