In 2003, Hwang et al. proposed a new blind signature based on the RSA cryptosystem. The Extended Euclidean algorithm is employed in their proposed scheme. They claimed that the proposed scheme was untraceable and it could meet all requirements of a blind signature. However, we find that the signer can still trace the blind signature applicant in some cases. Thus, we present the security flaw of Hwang et al.’s scheme in this paper.
Chang, Chinchen and Chang, Yafen, "The Security Flaw of an Untraceable Signature Scheme" (2004). ICEB 2004 Proceedings. 241.