The award was for "Resiliency Policies in Access Control Revisited" by J. Crampton, G. Gutin and R. Watrigant.
Resiliency refers to the extent to which a multi-user computer system, subject to an authorization policy, is able to continue functioning if a number of authorized users are unavailable. Several interesting problems connected to resiliency were introduced by Li, Wang and Tripunitara (ACM Trans. Inf. Syst. Secur. 2009). The paper proposes reductions from these problems to another problem in information security, which led to algorithms being efficient in the worst case and in practical computing.
For Jason Crampton and Gregory Gutin, this comes after a similar award at SACMAT 2015.
SACMAT is the ACM Symposium on Access Control Models and Technologies, which is the premier forum for the presentation of research results and experience reports on leading-edge issues in access control, including models, systems, applications, and theory.
Winning two Best Paper awards in a row is clear evidence that the access control community recognizes that research at Royal Holloway is world-leading in this important research area.