Apple TouchID allowing more than one fingerprint?

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I just got an iPhone 6+, with the TouchID sensor. I was experimenting with it, and noticed that the TouchID can store more than one fingerprint (for each "account", which means you can store over 5 fingerprints in total).

I did this by alternating my thumbs when setting it up- it took a little bit longer because it probably noticed that my thumbs are not the same, but I managed to complete setup and get both thumbs to work on only one "account". I haven't tried more fingers yet.

Is this a bug of Apple's TouchID? Is it a reliable way to store many more fingerprints on TouchID?

Thanks.

Jonathan Lam

Posted 2014-11-29T21:57:07.753

Reputation: 376

Question was closed 2014-12-01T16:06:52.997

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This question appears to be off-topic because it is about an iOS device. This should be migrated to Ask Different.SE.

– nc4pk – 2014-11-29T22:18:51.497

Answers

1

You can have 5. that's 2 fingers from one hand & 3 from the other. [I never tried for separate accounts, so I don't know if you get 5 fingerprints for each account or just 5 total]

Add each finger as a separate fingerprint; otherwise the poor thing will never figure out what you're trying to do.

Touch at several angles, simulating the randomness of any single unlock movement; the more area of the one digit that the sensor sees, the better the picture it builds of that single digit.

If you try to make a composite thumbprint from both hands… no-one on earth [including you] is ever going to match that thumbprint.

Tetsujin

Posted 2014-11-29T21:57:07.753

Reputation: 22 456

2It could also be the opposite, eg when a Composite thumbprint is made, the fingerprint controller will try to create a profile with a low FRR for 2 completely different fingerprint, which will cause that profile to have a extremely high FAR. Eg, theres a higher chance a unauthorized person could just use his own finger to unlock OP's iPhone. – sebastian nielsen – 2014-11-29T22:38:23.880

your work through had me guessing for a minute, but yes, agree - the randomness factor is increased massively. Result could be, in extremes, you are always locked out OR everyone can get in. – Tetsujin – 2014-11-29T22:42:15.347

And it depends on fingerprint controller. In some access controllers, the algoritm make the profile "stricter" for each touch when you enroll, and some fingerprint controllers make the profile less strict for each touch. According to OP, he was able to access with both thumbs after making a Composite profile, so the fingerprint controller is with very high degree of the more "user friendly" type which make the profile less strict for each touch (rather allowing in one unauthorized than locking out the real owner). – sebastian nielsen – 2014-11-29T22:47:51.803

1which is a really complicated way of saying "Use one digit for one ID; don't mess with the system" – Tetsujin – 2014-11-29T22:50:32.467

@Tetsujin you said "no-one on earth [including you] is ever going to match that thumbprint", but it works for both thumbs (I've tried it many times now, and it's been pretty reliable). But I agree- I guess I won't overly mess with the system, but I'll leave it there because it's cool. – Jonathan Lam – 2014-11-29T23:52:56.343

Asked: 2014-11-29T21:57:07.753

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Active: 2014-11-29T22:12:51.817