[allThumbs]

They'd need your whole hand, since any finger can be used for a smartphone biometric scanner.

Truthfully, lots of different scannable areas will unlock a phone. I've successfully and reliably configured my toes, the knuckles on my hands, and the tip of my nose. All of them work pretty good.

Unless observed using biometric security in a specific manner, an adversary might have a hard time deducing what kind of print will provide access.

Even if they've determined that the phone contains biometric scans tied to security, how would they know it's yours, and not someone else's, or even a specially printed 3D key ring fob or something?

Then again, criminals don't always think deeply about such details during a crime. They might just chop off both hands, grab the phone, and figure out the rest on the run.

[gpderetta]

It will very satisfying to know they can't unlock your device after they hack off your fingers.

Tongue only slightly in cheek.

[baldeagle]

Well, only in cheek until it too is removed in search of the unlocking appendage.

[toxican]

If you're robbing an iPhone user, you'd probably be safe hacking off a thumb. Can't imagine many people give up the convenience of using their thumbs to unlock.

With me they'd have to take my index fingers because I've got a phone with the reader on the back of the device (which, imo, is the best place to put it, as far as convenience goes.)

[newscracker]

> If you're robbing an iPhone user, you'd probably be safe hacking off a thumb. Can't imagine many people give up the convenience of using their thumbs to unlock.

Anecdotal, but I know people who have configured only the index finger to unlock the phone because they prefer it to the thumb.

[Cozumel]

If you wanna know something and he won't tell you, cut off one of his fingers. The little one. Then tell him his thumb's next. After that he'll tell you if he wears ladies underwear.