ID-Based Directed Multi-Proxy Signature Scheme from Bilinear Pairings

In a multi-proxy signature scheme, an original signer delegates his signing power to a group of proxy signers. Then the group of proxy signers cooperatively generates a multi-proxy signature on behalf of the original signer; and any one can verify the validity of the multi-proxy signature. But, when the signed message is sensitive to the signature receiver, it is necessary to combine the concepts of multi-proxy signatures with directed signatures. In this paper, we propose an identity based directed multi-proxy signature scheme using bilinear pairings. This scheme allows a group of proxy signers to generate a valid multi-proxy signature to a designated verifier. The designated verifier can only directly verify the multi-proxy signature generated by a group of proxy signers issued to him on behalf of the original signer and, in case of trouble or if necessary, he can convince any third party about the validity of the signatures. Finally, we discuss the correctness and security analysis of the proposed scheme.