A provably secure identity-based proxy ring signature based on RSA

Proxy ring (anonymous proxy) signatures allow an entity to delegate its signing capability

to a group of entities (proxy group) such that only one of the members in the proxy group can generate a

proxy signature on behalf of the delegator while privacy of the proxy signer is protected. Identity-based

versions of proxy ring signatures employ identity strings in place of randomly generated public keys. Our

contribution is two-fold. First, we formalize a security model for identity-based proxy ring signatures.

We note that there exists no formal security model for identity-based proxy ring signatures prior to our

work. Second, we present the rst provably secure identity-based proxy ring signature scheme using a

new paradigm called sequential aggregation. The construction is proved secure, under the one-wayness

assumption of RSA, in the random oracle model by presenting a new forking lemma.We should highlight

that the proxy key exposure attack cannot be applied to our scheme. Further, in contrast to the existing

schemes that are based on pairings, our scheme is based on RSA; therefore, it outperforms the existing

schemes in terms of eciency and practicality.