A Secure Anonymous Proxy Multi-signature Scheme

A proxy signature scheme enables a signer to delegate its signing rights to any other user, called the proxy signer, to produce a signature on its behalf. In a proxy multi-signature scheme, the proxy signer can produce one single signature on behalf of multiple original signers. We propose an efficient and provably secure threshold-anonymous identity-based proxy multi-signature (IBPMS) scheme which provides anonymity to the proxy signer while also providing a threshold mechanism to the original signers to expose the identity of the proxy signer in case of misuse. The proposed scheme is proved secure against adaptive chosen-message and adaptive chosen-ID attacks under the computational Diffie-Hellman assumption. We compare our scheme with the recently proposed anonymous proxy multi-signature scheme and other ID-based proxy multi-signature schemes, and show that our scheme requires significantly less operation time in the practical implementation and thus it is more efficient in computation than the existing schemes.