Analysis of multi-path onion routing-based anonymization networks

Abstract

Anonymization networks (e.g., Tor) help in protecting the privacy of Internet users. However, the benefit of privacy protection comes at the cost of severe performance loss. This performance loss degrades the user experience to such an extent that many users do not use anonymization networks and forgo the privacy protection offered. Thus, performance improvements need to be offered in order to build a system much more attractive for both new and existing users, which, in turn, would increase the security of all users as a result of enlarging the anonymity set. A well-known technique for improving performance is establishing multiple communication paths between two entities. In this work, we study the benefits and implications of employing multiple disjoint paths in onion routing-based anonymization systems. We first introduce a taxonomy for designing and classifying onion routing-based approaches, including those with multi-path capabilities. This taxonomy helps in exploring the design space and finding attractive new feature combinations, which may be integrated into running systems such as Tor to improve users’ experience (e.g., in web browsing). We then evaluate existing implementations (together with relevant design variations) of multi-path onion routing-based approaches in terms of performance and anonymity. In the course of our practical evaluation, we identify the design characteristics that result in performance improvements and their impact on anonymity.