Public-key Support for Collaborative Groups

In this paper, we describe a use of public-key cryptography to achieve access control over communication and data transfers in order to support the work of collaborative groups. The participants form themselves into groups and access is granted to group members. The use of cryptography in this project is exceptional only in the care with which we designed the protocols for identity establishment. Our goal is to produce a working application that has the potential to be more secure than earlier alternatives, because it is easier to use correctly. This paper compares our identity establishment process, along the lines of SDSI, to that of an X.509 PKI or PGP, and shows the security advantages of the process we use. We also describe an experimental method for key verification intended to make strong key verification both easy and enjoyable for the average user.