Collusion analysis of cryptographic protocols

Abstract

As network applications such as electronic commerce proliferate, complex communications protocols that employ cryptographic building blocks, such as encryption and authentication, will become more common. We view a cryptographic protocol as a process by which information is transferred among some users and hidden from others. The collusion problem determines whether a subset of users can discover, through collusion, the information that is designed to be hidden from them after a protocol is executed. Earlier we introduced a model for cryptographic protocols and its collusion analysis, and solved a special case of the collusion problem. In this paper we present an algorithm that solves the general case.