(chapter 7), is professor of information systems security at the University of Kent, UK. He has been working on distributed authorization systems for over 20 years and was the architect of the PERMIS authorization infrastructure, the first implementation of X.509 attribute certificates. He has contributed to international standards for over 30 years, has co-authored two internet RFCs, was the editor of X.518, wrote substantial portions of X.509 privilege management, and is currently an invited expert to the W3C Verifiable Credentials Working Group.
