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The problem is that I can't change my fingerprint. If it gets out by some third-party abusing the secret backdoor (or just abusing whatever other place you have

by pilif 13y ago

The problem is that I can't change my fingerprint. If it gets out by some third-party abusing the secret backdoor (or just abusing whatever other place you have your fingerprint stored), then they can potentially forge your fingerprint when committing a crime or when otherwise attempting to access resources you have access to. When a third-party loses your password, you change it and life goes on (you are not reusing passwords, are you?). When a third-party loses your fingerprint, what do you do? Cut off your fingers? Grow a new hand? Yes. The fingerprint information is supposed to be irreversibly hashed. But so are passwords. And yet we still see them being stored unencrypted. No. I'm very careful with my fingerprints. Also, the data on my phone must be some of the most valuable data I have. When I lose my phone and you gain access, you immediately own all my online identities. My phone has SSH keys, it has the password to my Email account stored in its keychain (very handy for all these "I have forgotten my password" features on all the sites), it has my 2 factor authentication tokens - I can't even begin to imagine how bad it would be if somebody had access to my phone. Yours is probably as valuable to you.

therobot24 13y ago
you can rub off your fingerprints, it does occur, however is not very practical (though better than cutting off your hand)
- hjnilsson 13y ago
  They'll grow back eventually. So cutting off is the only option.
  - therobot24 13y ago
    I hardly doubt cutting them off is the only option. Tissue damage is definitely required, but burning (such as a chemical burn) would also work.
  - RyJones 13y ago
    I don't have fingerprints. A large part of the world population doesn't have readable prints. What now? People on blood thinners, elderly people, Asians, women all have less distinctive prints. I don't have prints due to psoriasis. Fingerprints are a horrible biometric.
    - gfodor 13y ago
      Saying that fingerprints are a bad biometric because some people can't use them is like saying escalators are a bad idea because some people can't use them. They might be a bad biometric but it's not because they aren't universally available to everyone.
      - RyJones 13y ago
        When it's used as a gate, it is an issue. It took the Seattle PD and whatever agency actually issues civilian CAC (HSPD-12) a long, long time to get enough prints to allow me access to do my job. Both eventually had to accept three very partial prints as evidence.
        cremnob 13y ago
        Looks like you'll be using the passcode as usual.
martin-adams 13y ago
The problem I see is that if they have a copy of your fingerprint, and then their computer says that matches a crime of sorts, what do you do then? You have to consider the false positives.
- therobot24 13y ago
  the probability of a false match + you being in the area with no alibi is very slim
gfodor 13y ago
This makes sense. However, the cops already have many peoples' fingerprints once they've been booked, and in general if someone wants your fingerprints they can usually get them. I think the question of fingerprint forgery is an important one but I would assume that in a real trial the evidence presented also considers the likelihood the fingerprints were forged. That said, I can see how this could potentially dramatically increase the availability of public fingerprints if it were hacked. More importantly the fact you can't reset your fingerprint is something I overlooked. I do think that in general though anyone building a system that relies exclusively on a fingerprint as a highly hack-resistent security measure is foolhardy regardless of how prevalent fingerprint data is. In other words, your iPhone passcode isn't protecting your data anymore than your fingerprint if someone gets their hands on your phone, so I don't really see how this point is material to if it's a good idea to use fingerprints to unlock phones.
sliverstorm 13y ago
They probably already have your fingerprint. I believe you usually have to give it to the DMV to get your license.
- hack_edu 13y ago
  Which offers a perfect chance for cross-referencing!
- pilif 13y ago
  In the country where I live (Switzerland), getting a drivers license thankfully does not involve somebody taking your fingerprint. Also, public transportation here rules to such an extent that not even having a drivers license is a perfectly valid option. I don't have one for example. My passport also is one of the last ones you could get without it containing any biometric data. As such, I'm reasonably sure that no third-party ever had access to my fingerprint. And I'd love for it to stay like this (see my parent comment for the reasons why)
  - sliverstorm 13y ago
    Why do you care if anybody gets your fingerprint, if you have already decided nobody can be trusted with your fingerprint and thus will never trust fingerprint based authentication? Once you are at that point, it's like your eye color or something. I don't care if other people get my eye color, because I will never use it to authenticate.
    - mcintyre1994 13y ago
      I'd hypothesise it's more likely somebody will use your fingerprint to identify you than your eye colour. For example, at a crime scene if your fingerprints are found you can hardly say "oh, I don't trust my fingerprint so I won't authenticate with it, ignore that" - like it or not, it's seen as being at least something to investigate. On the flip side I imagine a witness who reports only "green eyes" won't have their case followed for very long.
simonholroyd 13y ago
>> I'm very careful with my fingerprints. What does that even mean? You wear gloves in public all the time? You wipe down everything you touch? Which makes me wonder, aren't one's finger prints all over your iPhone exterior anyway. If someone steals one's phone wouldn't it be easier to dust it for prints than crack the security on the digital copy?
- iyulaev 13y ago
  Which makes me wonder, aren't one's finger prints all over your iPhone exterior anyway. If someone steals one's phone wouldn't it be easier to dust it for prints than crack the security on the digital copy? Ding ding ding! We have a winner. Almost as silly as not using a biometric logic because "what if they use a backdoor to get a photo of my face?"
  - hadem 13y ago
    Right but his also assumes that you have physical access to the device! That, and a finger printing kit and time to spare...
- minor_nitwit 13y ago
  Which makes the idea of a fingerprint reader on a phone somewhat nonsensical. Your password is all over the phone, and Mythbusters has proven how easy these are to fake.
  - LaGrange 13y ago
    Actually, it doesn't, because properly used biometric isn't a sole auth method. You want to use it coupled with at least a pin - then suddenly just looking over your shoulder isn't enough, you have to handle the phone carefully, or steal the fingerprints off your glass. That's more work, and makes it more costly and skill intensive. It's not impenetrable, but still quite efficient.
    - minor_nitwit 13y ago
oleganza 13y ago
Simply publish your fingerprint somewhere - then if anyone uses it to impersonate you, it won't matter. It's not quite the same with private keys because you can always generate some new keys and publicly revoke your key if it could have been compromised. Since you cannot regenerate your fingerprints and could have already lost them, simply revoke them up front. Edit: expanded on this in my blog: http://blog.oleganza.com/post/60865284958/key-revocation-and-fingerprints http://blog.oleganza.com/post/60865284958/key-revocation-and...

by pilif 13y ago

therobot24 13y ago

you can rub off your fingerprints, it does occur, however is not very practical (though better than cutting off your hand)

hjnilsson 13y ago
They'll grow back eventually. So cutting off is the only option.
- therobot24 13y ago
  I hardly doubt cutting them off is the only option. Tissue damage is definitely required, but burning (such as a chemical burn) would also work.
- RyJones 13y ago
  I don't have fingerprints. A large part of the world population doesn't have readable prints. What now? People on blood thinners, elderly people, Asians, women all have less distinctive prints. I don't have prints due to psoriasis. Fingerprints are a horrible biometric.
  - gfodor 13y ago
    Saying that fingerprints are a bad biometric because some people can't use them is like saying escalators are a bad idea because some people can't use them. They might be a bad biometric but it's not because they aren't universally available to everyone.
    - RyJones 13y ago
      When it's used as a gate, it is an issue. It took the Seattle PD and whatever agency actually issues civilian CAC (HSPD-12) a long, long time to get enough prints to allow me access to do my job. Both eventually had to accept three very partial prints as evidence.
      - cremnob 13y ago
        Looks like you'll be using the passcode as usual.

martin-adams 13y ago

The problem I see is that if they have a copy of your fingerprint, and then their computer says that matches a crime of sorts, what do you do then? You have to consider the false positives.

therobot24 13y ago
the probability of a false match + you being in the area with no alibi is very slim

gfodor 13y ago

This makes sense. However, the cops already have many peoples' fingerprints once they've been booked, and in general if someone wants your fingerprints they can usually get them. I think the question of fingerprint forgery is an important one but I would assume that in a real trial the evidence presented also considers the likelihood the fingerprints were forged. That said, I can see how this could potentially dramatically increase the availability of public fingerprints if it were hacked. More importantly the fact you can't reset your fingerprint is something I overlooked. I do think that in general though anyone building a system that relies exclusively on a fingerprint as a highly hack-resistent security measure is foolhardy regardless of how prevalent fingerprint data is. In other words, your iPhone passcode isn't protecting your data anymore than your fingerprint if someone gets their hands on your phone, so I don't really see how this point is material to if it's a good idea to use fingerprints to unlock phones.

sliverstorm 13y ago

They probably already have your fingerprint. I believe you usually have to give it to the DMV to get your license.

hack_edu 13y ago
Which offers a perfect chance for cross-referencing!
pilif 13y ago
In the country where I live (Switzerland), getting a drivers license thankfully does not involve somebody taking your fingerprint. Also, public transportation here rules to such an extent that not even having a drivers license is a perfectly valid option. I don't have one for example. My passport also is one of the last ones you could get without it containing any biometric data. As such, I'm reasonably sure that no third-party ever had access to my fingerprint. And I'd love for it to stay like this (see my parent comment for the reasons why)
- sliverstorm 13y ago
  Why do you care if anybody gets your fingerprint, if you have already decided nobody can be trusted with your fingerprint and thus will never trust fingerprint based authentication? Once you are at that point, it's like your eye color or something. I don't care if other people get my eye color, because I will never use it to authenticate.
  - mcintyre1994 13y ago
    I'd hypothesise it's more likely somebody will use your fingerprint to identify you than your eye colour. For example, at a crime scene if your fingerprints are found you can hardly say "oh, I don't trust my fingerprint so I won't authenticate with it, ignore that" - like it or not, it's seen as being at least something to investigate. On the flip side I imagine a witness who reports only "green eyes" won't have their case followed for very long.

simonholroyd 13y ago

>> I'm very careful with my fingerprints. What does that even mean? You wear gloves in public all the time? You wipe down everything you touch? Which makes me wonder, aren't one's finger prints all over your iPhone exterior anyway. If someone steals one's phone wouldn't it be easier to dust it for prints than crack the security on the digital copy?

iyulaev 13y ago
Which makes me wonder, aren't one's finger prints all over your iPhone exterior anyway. If someone steals one's phone wouldn't it be easier to dust it for prints than crack the security on the digital copy? Ding ding ding! We have a winner. Almost as silly as not using a biometric logic because "what if they use a backdoor to get a photo of my face?"
- hadem 13y ago
  Right but his also assumes that you have physical access to the device! That, and a finger printing kit and time to spare...
minor_nitwit 13y ago
Which makes the idea of a fingerprint reader on a phone somewhat nonsensical. Your password is all over the phone, and Mythbusters has proven how easy these are to fake.
- LaGrange 13y ago
  Actually, it doesn't, because properly used biometric isn't a sole auth method. You want to use it coupled with at least a pin - then suddenly just looking over your shoulder isn't enough, you have to handle the phone carefully, or steal the fingerprints off your glass. That's more work, and makes it more costly and skill intensive. It's not impenetrable, but still quite efficient.
  - minor_nitwit 13y ago

oleganza 13y ago

Simply publish your fingerprint somewhere - then if anyone uses it to impersonate you, it won't matter. It's not quite the same with private keys because you can always generate some new keys and publicly revoke your key if it could have been compromised. Since you cannot regenerate your fingerprints and could have already lost them, simply revoke them up front. Edit: expanded on this in my blog: http://blog.oleganza.com/post/60865284958/key-revocation-and-fingerprints http://blog.oleganza.com/post/60865284958/key-revocation-and...