Smartphones store a significant amount of personal and private information, and are playing an increasingly important role in people's lives. It is important for authentication techniques to be more resistant against two known attacks called shoulder surfing and smudge attacks. In this work, we propose a new technique called 3D Pattern. Our 3D Pattern technique takes advantage of a new input paradigm called pre-touch, which could soon allow smartphones to sense a user's finger position at some distance from the screen. We implement the technique and evaluate it in a pilot study (n=6) by comparing it to PIN and pattern locks. Our results show that although our prototype takes about 8 seconds to authenticate, it is immune to smudge attacks and promises to be more resistant to shoulder surfing.
In this paper, we present SwiPIN, a novel authentication system that allows input of traditional PINs using simple touch gestures like up or down and makes it secure against human observers. We present two user studies which evaluated different designs of SwiPIN and compared it against traditional PIN. The results show that SwiPIN performs adequately fast (3.7 s) to serve as an alternative input method for risky situations. Furthermore, SwiPIN is easy to use, significantly more secure against shoulder surfing attacks and switching between PIN and SwiPIN feels natural. We evaluate the efficacy of shoulder surfing defenses for PIN-based authentication systems. We find tilting the device away from the observer, a widely adopted defense strategy, provides limited protection. We also evaluate a recently proposed defense incorporating an "invisible pressure component" into PIN entry. Contrary to earlier claims, our results show this provides little defense against malicious insider attacks. Observations during the study uncover successful attacker strategies for reconstructing a victim's PIN when faced with a tilt defense. Our evaluations identify common misconceptions regarding shoulder surfing defenses, and highlight the need to educate users on how to safeguard their credentials from these attacks.