This talk will focus on the problem of forward secrecy in group key exchange where most of the participants remain offline until they wish to compute the key. This is well suited to a cloud storage environment where users are often offline, but have online access to the server which can assist in key exchange. To meet the scenario requirements we define and instantiate a new primitive, a blinded KEM, which we show can be used in a natural way as part of our generic protocol construction. Our protocol construction is provably secure in a well-known model for group key exchange, and additionally is efficient when implemented using our concrete instantiation. The talk will close with a discussion of the role of forward secrecy in group key exchange protocols, with a focus on practical application scenarios. Joint work with Colin Boyd, Kristian Gjøsteen and Yao Jiang;
Gareth T. Davies completed his PhD at the University of Bristol in 2015 under the supervision of Martijn Stam and Bogdan Warinschi. After completing a short postdoc with Prof. Nigel Smart, he became a postdoc in the applied cryptography group at NTNU Trondheim with Colin Boyd and Kristian Gjøsteen.