Efficient convertible Limited Verifier Signatures

The notion of limited verifier signature (LVS) was first introduced by Araki et al. in 1999. It is a useful cryptographic primitive to limit the publicly verifiable property of ordinary digital signatures. In a LVS, the signature can be verified by a limited verifier. When necessary, the signer or the limited verifier can provide a proof to convince a designated verifier (eg., a judge) that the signer has indeed generated the signature. However, the judge cannot transfer this proof to convince any other party. Also, the LVS should be converted into an ordinary one for public verification if required. In this paper, we propose an efficient LVS scheme which is more efficient than previous proposed schemes. Based on the intractability of the Computational Diffie-Hellman (CDH) problem, we give the security proofs of the scheme in the random oracle model.