Robert Rolland

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We propose new results on low weight codewords of affine and projective generalized Reed-Muller codes. In the affine case we prove that if the size of the working finite field is large compared to the degree of the code, the low weight codewords are products of affine functions. Then in the general case we study some types of codewords and prove that they(More)
— Let us consider an algebraic function field defined over a finite Galois extension K of a perfect field k. We recall some elementary conditions allowing the descent of the definition field of the algebraic function field from K to k. We apply these results to the descent of the definition field of a tower of function fields. We give explicitly the(More)
A brief survey on low weight codewords of generalized Reed-Muller codes and projective generalized Reed-Muller codes is presented. In the affine case some information about the words that reach the second distance is given. Moreover the second weight of the projective Reed-Muller codes is estimated, namely a lower bound and an upper bound of this weight are(More)
We study the geometrical properties of the subgroups of the mutliplicative group of a "nite extension of a "nite "eld endowed with its vector space structure and we show that in some cases the associated projective space has a natural group structure. We construct some cyclic codes related to Reed}Muller codes by evaluating polynomials on these subgroups.(More)
This paper describes a new key forwarding protocol for networks messages exchange which guaranties both authentication of participants and forward security. The protocol lies within the framework of a keys derivation scheme used for spanning tree-based networks messages diffusion where compromising a key in a node involves compromising all derived keys in(More)