Two Improved Anonymous Authentication Methods for PCS

To avoid the weakness and also reduce the computation cost of Lee-Yeh’s anonymous authentication protocol, an improved scheme has been proposed by Lee-Chang, but it still needs too much message rounds. A double delegation-based scheme has been proposed by Ou-Hwang to reduce the message rounds. Though it needs only four message rounds which are two rounds less than the previous one, it is still considered to be further improved. This paper exploits two improved methods, one of which reduces one message round by accurately combining message parameters, and the other achieves efficiency by decreasing public-key computation on MS. The comparison shows that, our improvements are efficient and practical.