Forward-secure multisignature and blind signature schemes

Forward-secure signature schemes address the key exposure problem, in which all previously generated signatures are still considered to be valid even after the secret key is compromised. Multisignature scheme allow any subgroup of a group of users to jointly sign a document such that a verifier is convinced that each member of the subgroup participated in signing. Such schemes are very important technologies in this highly group-oriented society. Blind signature scheme are protocols for obtaining a signature from a signer, but the signer can neither learn the messages he/she sign nor the signatures the recipients obtain afterward. Such schemes are very important technologies in privacy oriented e-commerce applications. In this paper, we propose a forward-secure multisignature scheme and a forward-secure blind signature scheme. Our constructions are based on the recently proposed forward-secure signature scheme by bilinear pairings.