Operational Signature Schemes.
Michael Backes, Özgür Dagdelen, Marc Fischlin, Sebastian Gajek, Sebastian Meiser, Dominique Schröder · 2014
Functional encryption, as introduced by Boneh, Sahai, and Waters (TCC’11), gen-eralizes public-key encryption systems to include functional decryption capabilities. Recently, Boyle et al. as well as Bellare and Fuchsbauer (both PKC’14) formalized analogous notions for signature schemes. Here we discuss that both their notions are limited in terms of expressiveness in the sense that they cannot cast known signature schemes supporting operations on data in their frameworks. We therefore propose a notion of what we call, for sake of distinctiveness, operational signature schemes which captures functional signatures, policy-based signatures, sanitizable signatures, P-homomorphic signatures, ring signatures, aggregate signatures etc., and also their message authentication code counterparts. We discuss possible instantiations for operational signatures. We give some posi-tive result about achieving our general notion of operational signatures presenting a compact construction that relies on a new combination of indistinguishability obfusca-tion and random oracles. We then indicate that it is unlikely to be able to instantiate operational signature schemes in general using one-wayness and, under some circum-stances, even using specific “non-interactive ” assumptions like RSA.