A fundamental problem in cryptography is to send a message privately and reliably over a network that is partially controlled by a computationally unlimited adversary. Dolev, Dwork, Waarts and Yung defined a secure message transmission problem where the network is abstracted by a set of node disjoint paths, a subset of which is controlled by the adversary. Using this abstraction they showed that as long as a sufficient number of paths are uncorrupted, perfect secrecy and reliability can be achieved without requiring a shared key. In this talk, we give an overview of the secure message transmission problem, consider a variation of the problem that is attractive from a practical viewpoint, and discuss the challenges of secure implementation of the system in real-life networks. We show a side channel that breaks the perfect secrecy of the system and outline approaches that could mitigate the side channel.

Bio: Rei Safavi-Naini is the NSERC/Telus Industrial Research Chair in Information Security at the University of Calgary. She is the co-founder of the Institute for Security, Privacy and Information Assurance at the University of Calgary, and served as its Director until December 2018. Before joining the University of Calgary in 2007, she was a Professor of Computer Science and the Director of Telecommunication and Information Technology Research Institute at the University of Wollongong in Australia. She has served as Associate Editor of IEEE Transactions on Information Theory, IEEE Transactions on Dependable and Secure Computing, ACM Transactions on Information and System Security (TISSEC) and is currently Associate Editor of ACM Computing Surveys and Journal of Mathematical Cryptology. Her research interest is cryptography and information theoretic security.