Diana K. Smetters

Secret handshakes from pairing-based key agreements

Consider a CIA agent who wants to authenticate herself to a server but does not want to reveal her CIA credentials unless the server is a genuine CIA outlet. Consider also that the CIA server does not want to reveal its CIA credentials to anyone but CIA agents - not even to other CIA servers. We first show how pairing-based cryptography can be used to implement such secret handshakes. We then propose a formal definition for secure secret handshakes, and prove that our pairing-based schemes are secure under the Bilinear Diffie-Hellman assumption. Our protocols support role-based group membership authentication, traceability, indistinguishability to eavesdroppers, unbounded collusion resistance, and forward repudiability. Our secret-handshake scheme can be implemented as a TLS cipher suite. We report on the performance of our preliminary Java implementation.

Moving from the design of usable security technologies to the design of useful secure applications

Recent results from usability studies of security systems have shown that end-users find them difficult to adopt and use. In this paper we argue that improving the usability of security technology is only one part of the problem, and that what is missed is the need to design usable and useful systems that provide security to end-users in terms of the applications that they use and the tasks they want to achieve. We propose alternate ways of building and integrating security technologies into applications and usability methods for evaluating how successful our prototypes are. We believe that the end results of designing usable and useful (from the end-user perspective) systems will be secure applications which will reflect the needs of users who are increasingly using computers away from the office and in a wider variety of networked configurations.