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Marian Harbach, Emanuel von Zezschwitz, Andreas Fichtner, Alexander De Luca, Matthew Smith
It's a Hard Lock Life: A Field Study of Smartphone (Un)Locking Behavior and Risk Perception
In Proceedings of the Tenth Symposium on Usable Privacy and Security (SOUPS '14). July 9-11 2014. USENIX Association, Menlo Park, USA. (bib)

A lot of research is being conducted into improving the usability and security of phone-unlocking. There is however a severe lack of scientiffic data on users' current unlocking behavior and perceptions. We performed an online survey (n = 260) and a one-monthfield study (n = 52) to gain insights into real world (un)locking behavior of smartphone users. One of the main goals was to find out how much overhead unlocking and authenticating adds to the overall phone usage and in how many unlock interactions security (i.e. authentication) was perceived as necessary. We also investigated why users do or do not use a lock screen and how they cope with smartphone-related risks, such as shoulder surfing or unwanted accesses. Among other results, we found that on average, participants spent around 2.9% of their smartphone interaction time with authenticating (9% in the worst case). Participants that used a secure lock screen like PIN or Android unlock patterns considered it unnecessary in 24.1% of situations. Shoulder surfing was perceived to be a relevant risk in only 11 of 3410 sampled situations.