My touch id fails to activate

Mariglenmusta

macrumors newbie
Original poster
May 2, 2016
4
1
Hi guys ☺. I am having a problem with my touch id on my iphone 6 that i got from a friend of mine. When i do to settings-touch id & passcode and when i try to enable it for iphone unlock it says failed and unable to activate touch id setup. What may be the problem?
 

Attachments


lordofthereef

macrumors G5
Nov 29, 2011
12,869
3,407
Boston, MA
I dont know for sure but i think he replaced the screen, but wont tell me cause i bought it from him
[doublepost=1462218639][/doublepost]
Can i repair it, if yes, should i buy a new sensor?
It needs to be paired and this can only be done by Apple; this is a security measure.

If it's been replaced by a third party, even just he screen, that's likely your problem. Whoever sold this to you should be more than willing to share that info with you. If it's been repaired by a bird party they effectively sold you a phone with a Touch ID that will never work and this should have been mentioned prior to sale.
 

electronicsguy

macrumors 6502a
Oct 12, 2015
531
207
Pune, India
It needs to be paired and this can only be done by Apple; this is a security measure.

If it's been replaced by a third party, even just he screen, that's likely your problem. Whoever sold this to you should be more than willing to share that info with you. If it's been repaired by a bird party they effectively sold you a phone with a Touch ID that will never work and this should have been mentioned prior to sale.
actually it's not a security measure per se... that's just Apple's line you're (unintentionally) towing there. The reason is simple - according to Apple itself, the fingerprint signature is stored in a secure part of the "processor", no the sensor itself. The sensor simply passes on a unique key, alongwith the fingerprint data (bits). It's the processor that receives this data and matches it to the signature stored in it's secure vault.

now even if someone were to put a (malicious) 3rd party sensor, what difference would it make? The sensor still has to pass on the fingerprint data, and the processor has to match it. If the sensor doesn't pass the correct fingerprint data, the phone cannot be locked in any case. The touch-id "key" is irrelevant as far as real security is concerned.

It's just like say, the camera they use at border crossings, and the image is compared to the one in the database. Even is someone install a malicious camera, the image it sends still has to be matched to the one in the database, which will fail it it's not the same person.

the only thing you can argue is if the sensor can be programmed to always send a known value, regardless of whose finger is on it. In that case, the malicious person has somehow already hacked the internal secure vault to get that data in the first place. specific to that phone, not generic in any case. The touch-id key, then, again, is meaningless.
 
  • Like
Reactions: lordofthereef

lordofthereef

macrumors G5
Nov 29, 2011
12,869
3,407
Boston, MA
actually it's not a security measure per se... that's just Apple's line you're (unintentionally) towing there. The reason is simple - according to Apple itself, the fingerprint signature is stored in a secure part of the "processor", no the sensor itself. The sensor simply passes on a unique key, alongwith the fingerprint data (bits). It's the processor that receives this data and matches it to the signature stored in it's secure vault.

now even if someone were to put a (malicious) 3rd party sensor, what difference would it make? The sensor still has to pass on the fingerprint data, and the processor has to match it. If the sensor doesn't pass the correct fingerprint data, the phone cannot be locked in any case. The touch-id "key" is irrelevant as far as real security is concerned.

It's just like say, the camera they use at border crossings, and the image is compared to the one in the database. Even is someone install a malicious camera, the image it sends still has to be matched to the one in the database, which will fail it it's not the same person.

the only thing you can argue is if the sensor can be programmed to always send a known value, regardless of whose finger is on it. In that case, the malicious person has somehow already hacked the internal secure vault to get that data in the first place. specific to that phone, not generic in any case. The touch-id key, then, again, is meaningless.
You're probably right here. I don't understand it enough to really agree or disagree lol. I've just read what apples response to something like this is and repeated it (as you mentioned).

Regardless, I think the take home points are:
A. The seller shouldn't have any qualms about mentioning repair unless he or she is intentionally dishonest
B. Only apple can replace the Touch ID (and maybe even screen?) and keep Touch ID functional.

That latter point is a damn shame (and if you care to read my post history you will see I've been rather vocal on that subject) because Apple is often much more expensive than a third party.
 
  • Like
Reactions: electronicsguy