On fairness in simulatability-based cryptographic systems

Simulatability constitutes the cryptographic notion of a secure refinement and has asserted its position as one of the fundamental concepts of modern cryptography. Although simulatability carefully captures that a distributed protocol does not behave any worse than an ideal specification, it however does not capture any form of liveness guarantees, i.e., that something good eventually happens in the protocol. We show how one can extend the notion of simulatability to comprise liveness guarantees by imposing specific fairness constraints on the adversary. As the common notion of fairness based on infinite runs and eventual message delivery is not suited for reasoning about polynomial-time, cryptographic systems, we propose a new definition of fairness that enforces the delivery of messages after a polynomial number of steps. We provide strengthened variants of this definition by granting the protocol parties explicit guarantees on the maximum delay of messages. The variants thus c...

• Type: Conference
• Year: 2005
• Where: CCS
• Authors: Michael Backes, Dennis Hofheinz, Jörn Müller-Quade, Dominique Unruh
• Keywords: CCS 2005, Cryptographic Notion, Liveness Guarantees, Security Privacy, Specific Fairness Constraints