The use of formal methods to verify security protocols with respect to secrecy and authentication has become standard practice. In contrast, the formalization of other security goals, such as privacy, has received less attention. Due to the increasing importance of privacy in the current society, formal methods will also become indispensable in this area. Therefore, we propose a formal definition of the notion of anonymity in presence of an observing intruder. We validate this definition by analyzing a well-known anonymity preserving protocol, viz. onion routing.
Sjouke Mauw, Jan Verschuren, Erik P. de Vink