Handling Expected Polynomial-Time Strategies in Simulation-Based Security Proofs

The standard class of adversaries considered in cryptography is that of strict polynomial-time probabilistic machines. However, expected polynomial-time machines are often also considered. For example, there are many zero-knowledge protocols for which the only known simulation techniques run in expected (and not strict) polynomial time. In addition, it has been shown that expected polynomial-time simulation is essential for achieving constant-round black-box zero-knowledge protocols. This reliance on expected polynomial-time simulation introduces a number of conceptual and technical difficulties. In this paper, we develop techniques for dealing with expected polynomial-time adversaries in simulation-based security proofs.

• Type: Conference
• Year: 2005
• Where: TCC
• Authors: Jonathan Katz, Yehuda Lindell
• Keywords: Cryptography, Polynomial-time, Polynomial-time Probabilistic Machines, Polynomial-time Simulation, TCC 2005