Efficient lont-term Secure Universally Composable Commitments

Abstract

Long-term security ensures that a protocol remains secure even in the future, when the adversarial computational power could, potentially, become unlimited. The notion of universal composability preserves the security of a cryptographic protocol when it is used in combination with any other protocols, in possibly complex systems. The area of long-term universally composable secure protocols has been developed mostly by Müller-Quade and Unruh. Their research conducted so far has shown the existence of secure long-term UC commitments under general cryptographic assumptions, thus without having an emphasis on the efficiency of the protocols designed. Building on their work and using very efficient zero-knowledge proofs of knowledge from [CL02], this thesis presents a new long-term universally composable secure commitment protocol that is both efficient and plausible to use in practice.