"If you've ever handled a penny, the government's got your DNA. Why do you think they keep 'em in circulation?" - Simpsons

An internet-enabled smartphone fp-reader is probably just a little more accurate than a random penny floating about in society.......-_-

Actually, random banknotes can usually be traced to a specific person, so any DNA traces could probably be linked - there have been experiments that show that majority of non-tiny banknotes are [A] put in ATM [B] given out to a known person; [C] given to a shop/vendor; [D] retrieved by the bank. So, given multiple banknotes, they could reasonably list the identities of people who shopped in that shop, simply by looking at the banknote serial numbers.

That I can understand, but it's "approximate" info on a banknote that probably has a couple of fingerprints. Even if the store had a video-camera, it's gonna be a bit tough to figure out exactly who gave a given $20 bill to the cashier. And since this person is using cash and not a creditcard, all they got is a (usually bad-quality) store-cam of someone that they think is the one who handed a given $20 bill to the cashier... meh, that's pretty fuzzy. Even if I told the FBI that I'm going to the mall and I will spend a $20 bill this Saturday, I think it would still be exceedingly difficult to find the exact bill unless they were tailing me the whole time. In which case I've already been located & identified by the FBI as a person-of-interest within their physical reach, so I'm already as good as dead.

Do you have any source about such experiment? I've always wondered about the cash flows analytics!

A Simpsons' quote is also probably directed a little more towards the humour end of the scale.

They undoubtedly have the fingerprints of any American they care to (hell, they got mine during 4th grade when a police officer came to our school to "teach us about fingerprinting"). However iPhones are of course used throughout the world...

Even ignoring the specific issue of fingerprints, which I am not convinced is a major concern, the widespread use gives numerous other reasons for pause.

You could place a sticker over the reader/home button to block covert reading.

you accidentally touch it one time without cover - done. And all the stores where people come and try the devices... (personally as an immigrant i already have my fingerprints on file, so i have nothing to worry about, it is just very amusing to see how another couple of billions would be gathered as well once Android phones replicate the feature :)

Welcome to the Total Information Awareness world.

It takes 30-60 seconds to get a read the first time.

That is a FANTASTIC idea. Get ready to see a kickstarter showing cool button-covers or replacement buttons for those not afraid to open their iPhones.

Or a Kickstarter selling replica Bin Laden fingers.

10,000 of those would keep the NSA quite busy.

(I guess you'd need a live terrorist's finger to replicate though. Those NSA types are pretty smart.)

Stick a piece of tape over the home button. Problem solved.

It's your hardware after all. If you're worried about it, take steps to protect yourself.

Will that work? 'The internet' (e.g. http://news.cnet.com/8301-13579_3-57602245-37/iphone-5s-come...) claims the sensor uses capacitance, not a camera, so you might need tinfoil tape.

Well. Being cynical for a moment, that's a great way for Apple to guarantee the fingerprint scanner always gets a good capture.

If I ever own one of these phones, I might have to make it a point in my muscle memory to use my knuckle to press the home button.