Identity based designated multi-confirmer signature: a new type signature

Abstract

Designated confirmer signatures play an important role in e-commerce. In the verification of the designated confirmer signature, it is necessary that the signer or the designated confirmer confirms the signature to the verifier. In this paper, we present a new type designated confirmer signature called designated multi-confirmer signature. In designated multi-confirmer signature scheme, the signer delegates the ability of confirmation to a group of confirmers. The verification requires that the verifier cooperates with all n confirmers in the group, so the possibility that the confirmation ability is abused is reduced greatly. The identity based encryption scheme proposed by Boneh and Franklin in 2001 using bilinear pairings is the only practical identity based public-key encryption scheme so far. In this paper we firstly present the concept of designated multi-confirmer signature and give a concrete identity based scheme. Our scheme is compatible with Boneh and Franklin encryption scheme and can be used as identity based designated confirmer signature (when n = 1).