Cryptanalysis and improvement of an identity-based proxy multi-signature scheme

Abstract

A Proxy multi-signature scheme allows an authorized proxy signer to sign on a message on behalf of a group of original signers. Recently Cao and Cao proposed an identity-based proxy signature scheme and claimed that the scheme is provably secure in random oracle model. In this paper we have reviewed the scheme and proven that the scheme is vulnerable to chosen message attack under the defined security model. To prevent this attack, we propose an improvement over existing identity-based signature scheme.