@inproceedings{alt2015mobilehci,
 abstract = {Common user authentication methods on smartphones, such as lock patterns, PINs, or passwords, impose a trade-off between security and password memorability. Image-based passwords were proposed as a secure and usable alternative. As of today, however, it remains unclear how such schemes are used in the wild. We present the first study to investigate how image-based passwords are used over long periods of time in the real world. Our analyses are based on data from 2318 unique devices collected over more than one year using a custom application released in the Android Play store. We present an in-depth analysis of what kind of images users select, how they define their passwords, and how secure these passwords are. Our findings provide valuable insights into real-world use of image-based passwords and inform the design of future graphical authentication schemes.},
 acmid = {2785882},
 address = {New York, NY, USA},
 author = {Alt, Florian and Schneegass, Stefan and Shirazi, Alireza Sahami and Hassib, Mariam and Bulling, Andreas},
 booktitle = {Proceedings of the 17th International Conference on Human-Computer Interaction with Mobile Devices and Services},
 doi = {10.1145/2785830.2785882},
 isbn = {978-1-4503-3652-9},
 keywords = {Graphical passwords, images, security},
 location = {Copenhagen, Denmark},
 note = {alt2015mobilehci},
 numpages = {7},
 pages = {316--322},
 publisher = {ACM},
 series = {MobileHCI '15},
 timestamp = {2015.08.24},
 title = {Graphical Passwords in the Wild: Understanding How Users Choose Pictures and Passwords in Image-based Authentication Schemes},
 url = {https://www.unibw.de/usable-security-and-privacy/publikationen/pdf/alt2015mobilehci.pdf},
 year = {2015}
}