Proxy Re-signature Schemes

Abstract

In a proxy re-signature scheme a semi-trusted proxy acts as a translator between Alice and Bob to translate a signature from Alice into a signature from Bob on the same message. In the 12th ACM CCS 2005, Ateniese and Hohenberger presented two secure proxy re-signature schemes based on bilinear maps and left as open challenges the design of multi-use unidirectional systems and determining whether or not a proxy re-signature scheme can be built that translates one type of signature scheme to another.

To address the first open problem, Benoit Libert and Damien Vergnaud have given one solution based on bilinear groups. We propose another solution for the same problem using the property of forward-security. With a minor change in resigning key, we can make the scheme to behave as a multi-use bidirectional scheme. To address the second open problem, we have come up with schemes to convert Schnorr/ElGamal Signatures to RSA signature.