Optimal online/offline signature: how to sign a message without online computation
We propose a novel notion of signature named Optimal Online/Offline Signature. The new notion can be seen as an extension to the notion of online/offline signature, where our signature scheme allows all necessary computations to be carried out in the offline phase before the message is available and the signer does not need to conduct any computation to construct the final signature in the online phase. Although the same feature can be achieved from a one-time signature scheme, the large signature size of a one-time signature is a disadvantage. In this paper, we provide a solution that allows our signature to be aggregated into a short length (about 320 bits); hence it demonstrates a better applicability. We also give a generic construction and then extend it to an identity-based scenario.