Apple’s Touch ID: A 500ppi Fingerprint Sensor Built Into iPhone 5S Home Button

Re:Apple’s Touch ID: A 500ppi Fingerprint Sensor Built Into ... by georgemcbay on Tuesday September 10, 2013 @02:26PM (#6362049)

A dead finger is the same as a live one as far as capacitance goes unless it has been dead so long that all the moisture is gone, in which case you could just dip it in water prior to the scan.

Having said that, the idea of losing a finger to access the device doesn't really make much sense. You've got to incapacitate someone pretty well to take their finger off, so you might as well just force them to touch the phone while they are so incapacitated, unless you really like chopping off fingers.

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Re:Apple’s Touch ID: A 500ppi Fingerprint Sensor Built Into ... by trebor on Tuesday September 10, 2013 @02:57PM (#6362379)

Humans are pretty powerful conductors, are you sure that a sensitive capacitance sensor couldn't tell the difference between a finger and a finger attached to a body? I don't know it for a fact, but I'd be surprised if not.

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Re:Apple’s Touch ID: A 500ppi Fingerprint Sensor Built Into ... by georgemcbay on Tuesday September 10, 2013 @03:06PM (#6362488)

A garden variety capacitive sensor can't tell the difference between a human finger and a hot dog.

How do you propose it would beyond attempting to measure the amount of capacitance and mapping it to an accepted band? Attempting that is way too fragile a solution due to variability in humans and local weather conditions.

And even if you did put in the effort for that, an attacker could still fairly easily match the dead finger capacitance to the correct band pretty easily.

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