Insider Forgery Attacks on Wang-Lin-Chang Threshold Signature Schemes With Traceable Signers

Abstract

Wang,Lin and Chang(1998)proposed two threshold signature schemers, one is with a mutually trusted center and the other is not, that provide the ability to trace back who the participant signers are involved in the construction of the group signature for a given message if necessary. Lately, Tseng and Jan (1999) demonstrated two outsider forgery attacks on the Wang-Lin-Chang schemes. In this paper, we will demonstrate two insider forgery attacks on the Wang-Lin-Chang schemes. That is, any malicious participant signer can successfully forge a valid group signature for an arbitrarily chosen message by himself.