Biometrics – any good?

I think I already talked about this subject previously but not here. Anyhow, the subject bears repeating.

Many go “yippee!” at the mention of biometrics and start to think their user authentication problem is solved. Do not pay attention, they will end up in the newspaper headlines fairly soon, either for massive security failures or being bankrupt, or both.

Cartoon of a man being checked on biometric fe...

The problem is not a huge false negative rate, and it is not the huge false positive rate either. The problem is immutability of the characteristics. The biometric characteristics change slowly over time as you age and can be influenced by the environment but they cannot be changed at will (well, at least not easily). The problem is that whatever this thing is, it is a part of your body and is most of the time something you do not want to change even if you had a possibility to do so.

And that’s also why it is dangerous – you may end up losing a limb or two.

The first question that should be asked then, “what’s it good for, anyway?” A characteristic that is fairly stable, cannot easily be changed at will, – that’s a fairly reasonable user name, i.e. the user identification. Even then, it is a questionable approach because it is a good idea to let users change names.

Biometrics is definitely not any good for authentication, that is, proving that you are who you say you are. If you compare to the familiar authentication with passwords, you will notice that the means of authentication are supposedly:

  • secret or concealable
  • non-degradable
  • easily changeable in a controlled manner
  • transferrable in a controlled manner

And biometrics is none of that.

But why then? Oh, I do not expect to find a definitive answer to that but one thing could be that it looks cool in movies. The other is that biometrics were historically good for tracking people that are not actively resisting such tracking. But then we talk about politics and power and that is not the subject of this discussion at all. One thing is certain: whatever the reason to use biometrics is, it has absolutely nothing to do with security.

So when you see claims like “Biometric is the most secure and convenient authentication tool”, now you know that’s just utter nonsense and you should stay away from people (and companies) making such claims. Unless there isn’t enough nonsense in your life, of course.

When it’s your responsibility to implement a security system, try to stay away from biometrics, you’ll live a happier life. Leave it to Hollywood.

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