One of the more convenient security features added in Android 5.0 Lollipop is "smart lock." The feature has you pick a traditional lock screen—like PIN, pattern, or password—but it allows you to skip the security challenge if certain conditions are met. The first two in Lollipop allowed you to add a "Trusted Device," which would skip the lock screen if it you were connected to a certain bluetooth device, and "Trusted Face," which used facial recognition through the front facing camera.

Now Google has added a new smart lock: "Trusted Voice," which, as you might have guessed, uses your voice as your password. This smart lock kicks in when you use an "OK Google" voice command. Google is pushing voice commands more and more as a core part of Android, with devices like the Nexus 6 having always-on voice recognition. Some voice commands get blocked by a secure lock screen, though, making voice commands less useful. The new "Trusted Voice" smart lock solves that problem by bypassing the lock screen based on how you say "OK Google."

How secure is this system? We're wondering the same thing. The popup when you enable "Trusted Voice" warns that the feature is not as secure as a traditional lock screen and that "Someone with a similar voice or a recording of your voice could unlock your device." We'd love to test it out, but it hasn't rolled out to any of our devices yet—we only know about it thanks to a report from Android Police.

While Lollipop only launched with "Trusted Devices" and "Trusted Face," Google unbundled some lock screen functionality in Android 5.0, allowing it to add new smart locks to the system through Google Play Services. Since the launch of Lollipop, the company has been steadily adding more smart locks. There's Trusted Places, which bypasses the lock screen when you're at designated places like home or work, and the craziest one, "On-body detection," which keeps the phone unlocked while it's in your pocket but locked when it's placed on a table.

All of these unlocks are potentially spoofable, and we're sure enabling each one lowers the security of a device by some amount (though it's hard to quantify exactly how much). It's nice for users to be able to fine-tune the level of security they want, though.