**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 ${\mathbb{F}}_{q}$. You will be presented a picture composed of $n\times n$ pixels, crypted by such a sequence. This picture has $q$ colors, each color representing an element ${\mathbb{F}}_{q}$.

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.

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

Please take note that WIMS pages are interactively generated; they are not ordinary HTML files. They must be used interactively ONLINE. It is useless for you to gather them through a robot program.

- Description: decrypt a picture crypted by a psudo-random sequence. interactive exercises, online calculators and plotters, mathematical recreation and games, Pôle Formation CFAI-CENTRE
- Keywords: CFAI,interactive math, server side interactivity, algebra,coding, finite_field, cryptology, polynomials, cyclic_code,arithmetic