Multi-Designated Verifiers Signatures Revisited

Multi-Designated Verifier Signature (MDVS) is a privacy-oriented signature scheme in which the signature produced can only be verified by a specific set of users. A generic MDVS scheme was proposed recently, which can be constructed from some ring signature schemes and a secure multi-party computation (SMC) protocol. In this paper, we try to remove the requirement of the costly SMC. We propose two new generic constructions of MDVS from variants of existing cryptographic schemes, which are ring signature from anonymous subset and multi-chameleon hash function. Firstly, we propose a single add-on protocol which enables most of the existing identity-based (ID-based) ring signature schemes to support the feature of anonymous subset, so that they are admissible for the construction of MDVS. The same technique can be applied to many ring signature schemes. Three ID-based MDVS schemes are proposed as a result, which are the first in the literature. Secondly, we modify an existing chameleon hash function with key exposure freeness to a multi-chameleon hash function. Interestingly, these two techniques can be seen as Hess’s ID-based signature and Schnorr signature respectively, providing security assurance to our constructions.