Paper 2004/050

Yet another attack on a password authentication scheme based on quadratic residues with parameters unknown 1

Lizhen Yang, Xiaoyun Wang, Dong Zheng, Kefei Chen

Abstract

In 1988, Harn, Laih and Huang proposed a password authentication scheme based on quadratic residues. However, in 1995, Chang, Wu and Laih pointed out that if the parameters d b a , , and l are known by the intruder, this scheme can be broken. In this paper, we presented another attack on the Harn-Laih-Huang scheme. In our attack, it doesn’t need to know the parameters and it is more efficient than the Chang-Wu-Laih attack.