Constructions Of Cartesian Authentication Codes From Unitary Geometry

In this paper,two constructions of Cretesian authentication codes from unitary geometry over finite fields are presented.Assuming that the encoding rules are chosen according to uniform probability distribution,the probabilities P_I and P_s of a successful impersonation attack and a successful substitution attack, respectively,of these codes are also computed.Moreover,those codes so constructed,for which P_I and P_s are optimal,are also determined.