Another year, another workshop. Here are the proceedings of the seventh Cambridge International Workshop on Security Protocols. All very well, you may think, but can there really still be anything genuinely new to say? Is it not just the same old things a tiny bit better? Well, perhaps surprisingly, this year we discoveredsome radically new things beginning to happen. The reasons in retrospect are not far to seek: advances in technology, changes in the system context, and new types of consumer devices and applications have combined to expose new security requirements. This has led not only to new protocols and models, but also to known protocols being deployedindelicate newways,withpreviousfragilitiesofwatermarkingand- tual authentication, for example, becoming desirable features. At the workshop we identi?ed several of these developments and began to map out some lines of enquiry. This volume brings you a selection of deliberately disputatious position - pers, followed by not-quite-verbatim transcripts of the discussions which they provoked. As always, our purpose in making these proceedings available to you is the hope that they will move your thinking in an unexpected direction. If you ?nd your attention caught by something here, if it makes you pause to re?ect, or to think “why, that is justso wrong”,then good. We’re waiting for your mail.