Analysis of Sun et al.'s linkability attack on some proxy blind signature schemes

The proxy blind signature scheme allows the designated proxy signer using the proxy secret key to generate a blind signature on behalf of the original signer. Tan et al. presented the DLP-based and ECDLP based blind signature schemes. Awasthi and Lal proposed a improved DLP-based scheme later. Recently, Sun et al. presented linkability attack on Tan et al. s and Awasthi–Lal s proxy blind signature schemes respectively. In this paper, we show that Sun et al. s attack is failed and these schemes are still satisfy the unlinkability property. 2005 Elsevier Inc. All rights reserved.