The inherent weakness of typical mobile device unlocking approaches (PIN, password, graphic pattern) is that they demand time and attention, leading a majority of end users to disable them, effectively lowering device security. We propose a method for unlocking mobile devices by shaking them together, implicitly passing the unlocked state from one device to another. One obvious use case includes a locked mobile phone and a wrist watch, which remains unlocked as long as strapped to the user’s wrist. Shaking both devices together generates a one-time unlocking event for the phone without the user interacting with the screen. We explicitly analyze the usability critical impact of shaking duration with respect to the level of security. Results indicate that unlocking is possible with a true match rate of 0.795 and true non match rate of 0.867 for a shaking duration as short as two seconds.
@inproceedings{Findling_14_ShakeUnlockSecurelyUnlock,
  author = {Findling, Rainhard Dieter and Muaaz, Muhammad and Hintze, Daniel and Mayrhofer, Ren\'e},
  title = { {ShakeUnlock}: Securely Unlock Mobile Devices by Shaking
  		  them Together},
  booktitle = {Proc. {MoMM} 2014: 12th International Conference on
  		  Advances in Mobile Computing and Multimedia},
  year = {2014},
  pages = {165--174},
  address = {New York, NY, USA},
  month = dec,
  publisher = {ACM Press},
  note = { {Winner of the MoMM 2017 best paper award}},
  booktitle_short = {Proc. {MoMM} 2014},
  day = {8--10},
  documenturl = {http://www.mayrhofer.eu.org/downloads/publications/MoMM2014-Shake-Unlock-on-Wrist.pdf},
  doi = {10.1145/2684103.2684122},
  eventurl = {http://www.iiwas.org/conferences/momm2014/},
  isbn = {978-1-4503-3008-4},
  keywords = {accelerometer; authentication; frequency domain; mobile
  		  devices; shaking; time series analysis; usability;},
  location = {Kaohsiung, Taiwan},
  pubtype = {conference}
}