Password storage in Android M
While Android has received a number of security enhancements in the last few releases, the lockscreen (also know as the keyguard) and password storage have remained virtually unchanged since the 2.x days, save for adding multi-user support. Android M is finally changing this with official support for fingerprint authentication. While the code related to biometric support is currently unavailable, some of the new code responsible for password storage and user authentication is partially available in AOSP's master branch. Examining the runtime behaviour and files used by the current Android M preview reveals that some password storage changes have already been deployed. This post will briefly review how password storage has been implemented in pre-M Android versions, and then introduce the changes brought about by Android M. Keyguard unlock methods Stock Android provides three keyguard unlock methods: pattern, PIN and password (Face Unlock has been rebranded to 'Trusted face