Our second contribution is a generic construction for the notion which has a concurrent join protocol, meets strong security requirements, and offers efficient traceability, i.e.\ without requiring tracing managers to produce expensive zero-knowledge proofs for tracing correctness. To dispense with the expensive zero-knowledge proofs required in the tracing, we deploy a distributed tag-based encryption with public verifiability. Finally, we provide some concrete instantiations, which, to the best of our knowledge, are the first efficient provably secure realizations in the standard model simultaneously offering all the aforementioned properties. To realize our constructions efficiently, we construct an efficient distributed (and threshold) tag-based encryption scheme that works in the efficient Type-III asymmetric bilinear groups. Our distributed tag-based encryption scheme yields short ciphertexts (only 1280 bits at 128-bit security), and is secure under an existing variant of the standard decisional linear assumption. Our tag-based encryption scheme is of independent interest and is useful for many applications beyond the scope of this paper. As a special case of our distributed tag-based encryption scheme, we get an efficient tag-based encryption scheme in Type-III asymmetric bilinear groups that is secure in the standard model.
Category / Keywords: public-key cryptography / Group signatures, distributed traceability, distributed public-key encryption, standard model Original Publication (with major differences): Latincrypt 2014 Date: received 15 Oct 2014, last revised 21 Jun 2015 Contact author: eg6947 at googlemail com Available format(s): PDF | BibTeX Citation Version: 20150621:150419 (All versions of this report) Short URL: ia.cr/2014/833 Discussion forum: Show discussion | Start new discussion