Efficient Revocable Linkable Ring Signatures
摘要
Linkable ring signature allows a user to create an anonymous signature on behalf of a group, which can be traced for disclosing multiple signatures from the same user. It improves privacy and anonymity in applications like privacy-preserving e-voting and e-cash. On the other hand, the advanced anonymity might compromise decentralized applications like cryptocurrencies and the possibility of money laundering or terrorist financing may emerge. Although Linkable Ring Signatures may help detect policy violations like double-spending attacks in e-voting, and multiple transaction detection attacks in e-cash protocols without compromising anonymity, they lack mechanisms that would allow revoking malicious users who fail to comply with these policies. In this paper, we introduce an efficient revocable and linkable ring signature scheme that features mandatory revocability and linkability, and we prove its security in the random oracle model. Our construction builds on Liu et al.’s Schnorr-based linkable ring signatures. Compared to Zhang et al.’s revocable linkable ring signatures, our scheme significantly improves efficiency, reducing the time complexity of the signature and verification algorithms by a factor of four while also cutting the size of the signature in half.