Adaptive Security of Multi-Party Protocols, Revisited

Abstract: In this talk, we consider security guarantees for distributed protocols in the presence of an adversary that can adaptively corrupt parties based on information obtained during the protocol execution. Security against such strong adversaries is often called "adaptive security" and a significant body of literature is devoted to it. We define a new security guarantee, which is technically weaker than standard adaptive security but nevertheless captures security against a fully adaptive adversary. Known protocol examples separating between adaptive and static security are also insecure in our notion. Moreover, our notion avoids some of the technical problems such as the so-called "commitment problem" where the simulator is unable to consistently explain the internal state of a party with respect to its pre-corruption outputs.

Based on joint work with Martin Hirt and Ueli Maurer, which appeared at TCC 2021.

Suggested reading: ia.cr/2021/1175

Suggested video of similar (external) presentation: https://yu2.be/hFpYp2f_o3A