Abstract or Summary:
The proliferation of technology requiring user authentication has increased the number of passwords which users have to remember, creating a significant usability problem. This paper reports a usability comparison between a new mechanism for user authentication - Passfaces - and passwords, with 34 student participants in a 3-month field trial. Fewer login errors were made with Passfaces, even when periods between logins were long. On the computer facilities regularly chosen by participants to log in, Passfaces took a long time to execute. Participants consequently started their work later when using Passfaces than when using passwords, and logged into the system less often. The results emphasise the importance of evaluating the usability of security mechanisms in field trials.