Towards a framework for connection anonymity

Anonymising services have evolved from simple proxies to complex systems. Numerous techniques have been developed to thwart and confuse attackers, thereby improving the degree of anonymity. These techniques are often presented as additional advantages of specific anonymising services. Comparisons of anonymity services exist, however, there is a need for a more structured approach towards the understanding of the various techniques employed by these services. This paper takes a meta-level look at connection anonymity, how it has evolved and how and why certain design choices are made. A conceptual framework describing what we consider to be important connection anonymity factors will be proposed. We consider design factors, fundamental connection anonymity functions and objectives. The framework aims to provide for a more structured and formal view of current anonymising strategies and techniques. It should thereby set the stage for further advances in connection anonymity.