Public Key Cryptosystem and Binary Edwards Curves on the Ring

 Let be a finite ring of characteristic 2, where e2 = e and n is a positive integer. Let (a, d) 2 ( )2, such that a and d + a2 + a are invertible in , we study the binary Edwards curve over this ring, denoted by and we give a bijection between this curve and produces two binary Edwards curves defined on the finite field . Afterthat we study the addition law of binary Edwards curves over the ring . We end this work with cryptography applications, ElGamal twisted Edwards curve cryptosystem and Cramer-Shoup twisted Edwards curve cryptosystem.