A Practical Forward-Secure DualRing

Ring signature allows a signer to generate a signature on behalf of a set of public keys, while a verifier can verify the signature without identifying who the actual signer is. In Crypto 2021, Yuen et al. proposed a new type of ring signature scheme called DualRing. However, it lacks forward security. The security of DualRing cannot be guaranteed if the signer’s secret key is compromised. To address this problem, we introduce forward-secure DualRing, in which a signer can periodically update their secret key using a “split-and-combine” method. A practical instantiation of our scheme enjoys a logarithmic complexity in signature size and key size. Implementation and evaluation further validate the practicality of our proposed scheme.