A New Graphical Password Scheme Resistant to Shoulder-Surfing
This addresses security and usability issues in graphical passwords for PDA users, but it is incremental as it builds on existing methods like DAS and Story.
The paper tackles the problem of shoulder-surfing in graphical passwords by proposing a new scheme where users draw curves across password images, achieving resistance to observation while maintaining usability for PDAs, with a preliminary user study showing accurate and memorable password entry.
Shoulder-surfing is a known risk where an attacker can capture a password by direct observation or by recording the authentication session. Due to the visual interface, this problem has become exacerbated in graphical passwords. There have been some graphical schemes resistant or immune to shoulder-surfing, but they have significant usability drawbacks, usually in the time and effort to log in. In this paper, we propose and evaluate a new shoulder-surfing resistant scheme which has a desirable usability for PDAs. Our inspiration comes from the drawing input method in DAS and the association mnemonics in Story for sequence retrieval. The new scheme requires users to draw a curve across their password images orderly rather than click directly on them. The drawing input trick along with the complementary measures, such as erasing the drawing trace, displaying degraded images, and starting and ending with randomly designated images provide a good resistance to shouldersurfing. A preliminary user study showed that users were able to enter their passwords accurately and to remember them over time.