Cryptanalysis of a new blind signature based on the DLP

In 2004, Lee et al.´s proposed a new untraceable blind signature based on discrete logarithm problem(DLP) in order to enhance the security of Carmenisch et al.´s scheme. However, we show there are three mistakes in Lee et al.´s paper:1. We prove that the cryptanalysis proposed by Lee et al. is improper and the Carmenisch et al.´s scheme does meet the property of untraceability; 2. Though Lee et al.´s new scheme is untraceable, the proof method of its untraceability is wrong. Furthermore, we give a formal proof; 3. The signature requester of Lee et al.´s scheme can obtain one-more valid signatres by performing only one round of the protocol, which violates an important security requirement of signatures. So Lee et al.´s scheme is insecurity and does not have any advantage.