This fingerprint sensor and its potential use for payments is rather disturbing to me. I am (rightly, I would argue) apprehensive about general purpose computers acting in a "trustworthy" manner. I hope that this fingerprint sensor, which undoubtedly will be incorporated into authentication for payment systems, doesn't usher in a future of reliance on a fundamentally untrustworthy device. I really, really worry that the banks will jump on this as a way of limiting their fraud liability. (I'm thinking about how chip and PIN has been cited as a way to move fraud liability to the consumer.)<p>To dumb it down: I'm envisioning a crappy future where you'll end up with fraudulent charges on your credit card (via your Apple account) that you can't contest because the credit card company will say "Hey-- your fingerprint was used to authenticate this charge. Therefore you did it." I don't think that line of thinking is too cynical.<p>No quantity of assurances from Apple about how the fingerprint reader will be "firewalled" from third-party access will convince me. If the hardware and software were opened up for third-party analysis I might be convinced, but I really don't think that's going to happen.<p>This fingerprint reader amounts to a complex hardware and software system with a lot of moving parts. It <i>will</i> have exploitable bugs and <i>will</i> be hacked. I think it will ultimately used to defraud, too. Thinking about the mass harvest of fingerprint data from the public by an attacker (like, say, the NSA) also gives me the willies. Will it be possible for an attacker to steal fingerprint data and use it to compromise other biometric authentication systems? Will it be possible to use stolen fingerprint data to plant your fingerprints at a crime scene? How do you recover from the theft of biometric data? Are you issued a new thumb?<p>To be clear: I <i>hate</i> the current system of "secret numbers" embossed on plastic cards and encoded on magnetic stripes as a way of authenticating payments. At least, though, the plastic cards aren't battery-powered general purpose computers with radios attached to them. Bad as little bits of plastic and "secret numbers" are, my credit cards themselves can't betray me. A phone (or other sufficiently complex computer system) acting as my payment token most certainly could (and will).<p>As an aside: I don't have any RFID-chipped credit cards, nor will I. When I end up having no choice in the matter I'll microwave the cards before using them.