The Modelling and Analysis of Security Protocols: the CSP Approach

10.6. Conference and group keying

Most of the key establishment protocols in the literature are concerned with setting up secret communication between a pair of users. Some applications, secure group-working for example, require a group (involving more than two participants) to share a common key. Often the schemes are also required to be able to deal efficiently with highly dynamic groups, with agents joining and leaving (or being ejected) frequently, and often also to deal with the merging of groups. A number of protocols to achieve this in a reasonably efficient way have been put forward, for example the papers by Burmester and Desmedt [18, 19] and, more recently in the Cliques project [96]. Most suffer from problems of authentication, performance ...