Comments on the Yang-Chang-Hwang anonymous conference key distribution system

摘要

Yang et al. [Comput. Stand. Interfaces 25 (2003)] proposed a conference key distribution system (CKDS) based on the elliptic curve discrete logarithm problem (ECDLP).Their scheme used a line with a hash value to broadcast the conference key.In this article,we point out that it suffers from the attack by solving linear equations to obtain the hash value h_i.Thus,the conference key CK can be obtained by using the known parameter h_i.We also propose an improved scheme to overcome the weakness.