Practical anonymous proxy signature schemes without trusted alias issuers

Abstract

Anonymous proxy signature schemes are used to protect proxy signers’ privacy. Among the proposed anonymous proxy signature schemes, Shum and Wei’s scheme is more practical than the other proposed scheme. However, their scheme does not satisfy strong unforgeability, and their scheme needs the help of trusted alias issuers to protect the proxy signer’s anonymity. To overcome this disadvantage, Hwang and Hsu’s scheme is proposed. But Hwang and Hsu’s scheme still needs the help of trusted alias issuers. To remove the trusted alias issuers, a new practical anonymous proxy signature scheme is first one with the help of concurrent signature schemes to deal with the signatures exchange between the original signer and proxy signer. In the new scheme, the unused anonymous names of proxy signers keep secret to protect proxy signers’ privacy. Once the anonymous names are used, the original signers have the evidences to identify anonymous proxy singers at the same time. Therefore, the right of original signers is also protected.