Fully Structure-Preserving Signatures and Shrinking Commitments

摘要: Structure-preserving signatures are schemes in which public keys, messages, and all collections of source group elements some bilinear groups. In this paper, we introduce fully structure-preserving signature schemes, with the additional requirement that even secret keys should be elements. This new type allows for efficient non-interactive proofs knowledge key is useful designing cryptographic protocols strong security guarantees based on simulation paradigm where simulator has to extract on-line. To gain efficiency, construct shrinking trapdoor commitments. by itself an important primitive independent interest as it appears contradict a known impossibility result. We argue relaxed binding property lets us circumvent result while still retaining usefulness applications mentioned above.