In "real life"—unless there was some absolute urgency to the problem—you wouldn't try to reconstruct a smudged partial print; you'd just use social engineering/espionage tactics to get a good print.

(Remember that iOS locks and/or wipes devices after 10 failed attempts. You want to go to however much effort is required to be perfect the first time.)

I can think of a number of situations one could create where a person would have no incredulity about actually inking their fingers and carefully applying fingerprints to a piece of paper. Committed adversaries aren't scared of crimes like "impersonating a police officer", remember.

I imagine that sort of "committed adversary" is also quite capable of hitting you with a $5 wrench until you tell them the passcode...

They only have to hit you once, and then put your finger on the button

I was presuming the sort of high-profile target where kidnapping them would quickly get some snipers emplaced and/or a MOAB dropped on you. If you want to, say, steal a nuclear submarine, you can't just kidnap an admiral and force them to hand over the keys. :P

No, that's the inelegant solution. Blackmail works far better with far less blowback.

Or you just subvert their democracy and insert your own puppet commander-in-chief - that way you get _all_ the nuclear submarines...

> Remember that iOS locks and/or wipes devices after 10 failed attempts

You only get 5 attempts at TouchID - 10 attempts is for the passcode.

Well, 10 failed attempts doesn't necessarily hold water anymore.

Wasn't that whole "Can the FBI convince Apple to unlock this iPhone" case solved by backing up the NAND memory and constantly reflashing it after the 10 attempts were used up?

I imagine the same process can be applied in this case too

Things have changed in the iPhone 5s, you can't bypass the unlock limit by desoldering a NAND chip anymore.

This is absolutely not a lab condition. You can very easily extract a fingerprint from a glass or so, as was done e.g. with Wolfgang Schaeuble, a German politician

Or just take a photo:

https://www.youtube.com/watch?v=VVxL9ymiyAU

Did they then hack into his iPhone? What was the quality of that fingerprint?

Smartphone unlock as a service?