A probabilistic model for anonymity analysis of anonymous communication networks

Abstract

An anonymous communication network (ACN) is supposed to provide its users with anonymity attributes. As a practical matter, we need to have a means to predict the level of the anonymity provided by ACN. In this paper, we propose a probabilistic model for the security analysis of ACNs, thereby quantifying their loss of anonymity. To be precise, we have tried to obtain the probability distribution of potential senders of a message sent from an unknown source to a specific destination. With the probability distribution in hand, it is possible to define and derive some anonymity metrics. The evaluated metrics help us to gain an understanding of how much such a network may be vulnerable to attacks aiming at revealing the identity of senders of messages. Consequently, new rerouting policies and strategies can be utilized to increase the anonymity level of the network. The quantitative analysis is performed from a general perspective and the applicability of the model is not limited to a specific network. The evaluation process of the metrics using the proposed model is clarified by an illustrative example.