3 ms·

Ok, I get it! If I understand it correctly, if it's lossless, 2 different fingerprints could pass the test (collision)? So by a bruteforce technique, I could b

by gren 13y ago

Ok, I get it! If I understand it correctly, if it's lossless, 2 different fingerprints could pass the test (collision)? So by a bruteforce technique, I could be able to generate a subset of all possible fingerprint (finite?). Tell me if I'm wrong, but maybe by "cross checking" with another data (e.g. another device with a second different conversion algorithm) I could finally find out what was your fingerprint! That's quite overkill though!

denzil_correa 13y ago
>Tell me if I'm wrong, but maybe by "cross checking" with another data (e.g. another device with a second different conversion algorithm) I could finally find out what was your fingerprint! Sure, but that's not the same as reverse engineering your fingerprint from the "mathematical representation". It isn't possible for your actual fingerprint image to be reverse-engineered from this mathematical representation.
interpol_p 13y ago
Think of it like this. We can oversimplify what Apple is doing with Touch ID. Let's say when you scan your fingerprint Apple breaks it down into three key properties, A B and C. Each fingerprint has a different percentage for A B and C. So yours might read as A 50% B 30% C 0% This data is then cryptographically hashed with some unique identifier inside the phone (so the same data would store differently on every iPhone). The data is then irreversibly transformed into a different representation. You can't retrieve the unique properties of the fingerprint, nor can you retrieve the fingerprint itself. In the linked article, Apple states that the probability of two fingerprints matching in Touch ID is 1 in 50,000. So that just means that their algorithm for breaking fingerprints down into key features discards enough information that it is possible to read two different human fingerprints as the same fingerprint.

by gren 13y ago

denzil_correa 13y ago

>Tell me if I'm wrong, but maybe by "cross checking" with another data (e.g. another device with a second different conversion algorithm) I could finally find out what was your fingerprint! Sure, but that's not the same as reverse engineering your fingerprint from the "mathematical representation". It isn't possible for your actual fingerprint image to be reverse-engineered from this mathematical representation.

interpol_p 13y ago

Think of it like this. We can oversimplify what Apple is doing with Touch ID. Let's say when you scan your fingerprint Apple breaks it down into three key properties, A B and C. Each fingerprint has a different percentage for A B and C. So yours might read as A 50% B 30% C 0% This data is then cryptographically hashed with some unique identifier inside the phone (so the same data would store differently on every iPhone). The data is then irreversibly transformed into a different representation. You can't retrieve the unique properties of the fingerprint, nor can you retrieve the fingerprint itself. In the linked article, Apple states that the probability of two fingerprints matching in Touch ID is 1 in 50,000. So that just means that their algorithm for breaking fingerprints down into key features discards enough information that it is possible to read two different human fingerprints as the same fingerprint.