Volker Roth, Kai Richter, Rene Freidinger. A PIN-entry method resilient against shoulder surfing. In Vijayalakshmi Atluri, Birgit Pfitzmann, Patrick Drew McDaniel, editors, Proceedings of the 11th ACM Conference on Computer and Communications Security, CCS 2004, Washingtion, DC, USA, October 25-29, 2004. pages 236-245, ACM, 2004. [doi]
Abstract is missing.