Proxy Re-signature Scheme That Translates One Type of Signature Scheme to Another Type of Signature Scheme

Abstract

In 1998, Blaze, Bleumer, and Strauss (BBS) proposed proxy re-signatures, in which 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. The proxy, however, does not learn any signing key and cannot sign arbitrary messages on behalf of either Alice or Bob. In the 12th ACM Conference on Computer and Communications Security (CCS 2005), Ateniese and Hohenberger formalised the definition of security for a proxy re-signature and presented two secure proxy re-signature schemes based on bilinear maps. They left open the problem of determining whether or not a proxy re-signature scheme can be built that translates one type of signature scheme to another i.e. a scheme that translates Alice’s Schnorr signatures into Bob’s RSA based ones. In this paper we address this open problem. We construct proxy signature scheme that translates Alice’s Schnorr/ElGamal signature to Bob’s RSA signature. We construct this by generating suitable proxy re-sign keys by establishing communication among delegatee, proxy signer and the delegator. At no point of conversion the security of Schnorr, ElGamal and RSA signature schemes are compromised. The Signatures generated by regular signature generation algorithm and the proposed re-signature algorithm are indistinguishable