Secure Protocols for Complex Tasks in Complex Environments

Abstract

Over the last two decades, there has been tremendous success in placing cryptography on a sound theoretical foundation, and building an amazingly successful theory out of it. The key elements in this Modern Cryptographic Theory are the definitions capturing the intuitive, yet elusive notions of security in various cryptographic settings. The definitions of the early 80’s proved to be extremely successful in this regard. But with time, as the theory started addressing more and more complex concerns, further notions of security had to be introduced. One of the most important concerns theory ventured into is of complex environments where different parties are communicating with each other concurrently in many different protocols. A series of efforts in extending security definitions led to the paradigm of Universally Composable (UC) Security [1], which along with modeling a general complex network of parties and providing definitions of security in that framework, provided powerful tools for building protocols satisfying such definitions.