Arithmetic geometry cryptography and coding theory 2009 : 12th Conference on Arithmetic Geometry Cryptography and Coding Theory March 30 April 3 2009 Marseille France ; Geocrypt Conference April 27 May 1 2009 Point à Pitre Guadelope France ; European Science Foundation Exploratory Workshop Curves Coding Theory and Cryptography March 25 29 2009 Marseille France Differentially 4 uniform functions Yves Aubry and François Rodier Computing Hironakas variants : Ridge and directrix Jérémy Berthomieu Pascal Hivert and Hussein Mourtada Nondegenerate curves of low genus over small finite fields Wouter Castryck and John Voight Faster side channel resistant elliptic curve scalar multiplication Alexandre Venelli and François Dassance Non linéarité des fonctions booléennes données par des polynômes de degré binaire 3 définies sur F[subscript 2m] avec m pair Eric Férard and François Rodier A note on a maximal curve Arnaldo Garcia and Henning Stichtenoth Computing Humbert surfaces and applications David Gruenewald Genus 3 curves with many involutions and application to maximal curves in characteristic 2 Enric Nart and Christophe Ritzenthaler Uniqueness of low genus optimal curves over F₂ Alessandra Rigato Group order formulas for reductions of CM elliptic curves Alice Silverberg Families of explicit isogenies of hyperelliptic Jacobians Benjamin Smith Computing congruences of modular forms and Galois representations modulo prime powers Xavier Taixés i Ventosa and Gabor Wiese