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.