Universally Composable End-to-End Secure Messaging

Ran Canetti, Palak Jain, Marika Swanberg, Mayank Varia

Abstract: We model and analyze the Signal end-to-end messaging protocol within the UC framework. In particular: Our modeling introduces additional innovations that enable arguing about the security of Signal irrespective of the underlying communication medium, as well as secure composition of dynamically generated modules that share state. These features, together with the basic modularity of the UC framework, will hopefully facilitate the use of both Signal-as-a-whole and its individual components within cryptographic applications. Two other features of our modeling are the treatment of fully adaptive corruptions, and making minimal use of random oracle abstractions. In particular, we show how to realize continuous key exchange in the plain model, while preserving security against adaptive corruptions.