My disk is encrypted, but all it takes to bypass this protection is for an attacker — a malicious hotel housekeeper, or “evil maid,” for example — to spend a few minutes physically tampering with it without my knowledge. If I come back and continue to use my compromised computer, the attacker could gain access to everything.Edward Snowden and his friends have a solution. The NSA whistleblower and a team of collaborators have been working on a new open source Android app called Haven that you install on a spare smartphone, turning the device into a sort of sentry to watch over your laptop. Haven uses the smartphone’s many sensors — microphone, motion detector, light detector, and cameras — to monitor the room for changes, and it logs everything it notices. The first public beta version of Haven has officially been released; it’s available in the Play Store and on F-Droid, an open source app store for Android.