Other (not refereed)

[1] R. Mayrhofer and I. Ion, “OpenUAT: The open source ubiquitous authentication toolkit,” Tech. Rep. 657, ETH Zurich, August 2010. [ bib | conference link | .pdf ]
Authenticating spontaneous interactions between devices and users is challenging for several reasons: the wireless (and therefore invisible) nature of device communication, the heterogeneous nature of devices and lack of appropriate user interfaces in mobile devices, and the requirement for unobtrusive user interaction. The most promising approach that has been proposed in literature involves the exploitation of so-called auxiliary channels for authentication to bridge the gap between usability and security. This concept has spawned the independent development of various authentication methods and research prototypes, that, unfortunately, remain hard to compare and interchange and are rarely available to potential application developers. We built a system which implements and unifies these approaches. In this paper, we present OpenUAT, an open source toolkit that implements our novel, unified cryptographic authentication protocol (UACAP), and a comprehensive range of specific auxiliary channels. We evaluated OpenUAT based on a user study in which we compared four authentication methods implemented by the toolkit. The user study showed that users tend to prefer the visual channel in spite of its comparatively poor performance.

[2] R. Mayrhofer, H. Gellersen, and M. Hazas, “An authentication protocol using ultrasonic ranging,” Tech. Rep. COMP-002-2006, Lancaster University, October 2006. [ bib | http | .pdf ]
This report presents a method for establishing and securing spontaneous interactions on the basis of spatial references which are obtained by accurate sensing of relative device positions. Utilising the Relate ultrasonic sensing system, we construct an interlocked protocol using radio frequency messages and ultrasonic pulses for verifying that two devices share a secret. This verification is necessary to prevent man-in-the-middle attacks on standard Diffie-Hellman key agreement.

[3] A. Ferscha, M. Hechinger, and R. Mayrhofer, “The peer-to-peer coordination framework --- architecture reference,” tech. rep., Johannes Kepler Universität Linz, Institut für Pervasive Computing, 2004. [ bib ]