Secure and Anonymous Communications Over Delay Tolerant Networks

Today's society has a fundamental need for security and anonymity. Well suited, real-life scenarios such as whistleblower reports, intelligence service operations, and the ability to communicate within oppressive governments, call for such fundamental needs. The contribution and focus of this paper is the study of anonymous communications in the context of Delay Tolerant Networks (DTNs). Current literature achieves anonymity via mechanisms that are built around the onion routing paradigm which, unfortunately, is vulnerable to malicious nodes. Instead, our work introduces a novel message forwarding algorithm that delivers messages, from source to destination, via a random walk process. As such, our protocol does not list the intermediate nodes along the route's path and, therefore, enhances significantly the anonymity of the underlying communications. We propose two different approaches for encrypting the exchanged messages. The first one is based solely on public key cryptosystems and is, thus, suitable for short, SMS-style messaging. The second one is a hybrid solution that combines both public and symmetric key cryptography and is targeted towards large multimedia messages, such as images or video. Through extensive simulation experiments, we show that our proposed anonymous routing protocol achieves high message delivery rates, while using modest computational resources on the mobile devices.