Friday, February 07, 2014

Something you have (and some other things you have)

The trinity of 'Something you know, something you have, and something you are' is the default model for describing authentication options.

The three are traditionally described as follows

  1. The 'know' factor is a secret like a password or a PIN. 
  2. The 'have' factor is some physical object in your possession. 
  3. The 'are' factor is a biometric like finger or retina print.
Think about the 'have'. It's clearly not enough to merely have possession of a SecureId or smart phone. You have to demonstrate (or prove) possession of that object. Typically, possession is proved by entering in some OTP, or responding to a challenge sent to that object. 

Now consider the 'know'. When I enter a password to login, what am I doing other than proving possession of (the knowledge of) the shared secret?

And for the 'are' factor, when I enter Canada using a Nexus kiosk, what am I doing other than proving possession of my retinas?

Would it not be simpler to model all authentication operations as 

Something you have (with various proof mechanisms) 

We are headed to a future where the things we have (see this) will be more and more involved in our authentication. While the phone may have primacy at the moment, over time it will become just one of many devices floating around us with an opinion on our status & presence (and an ability to assert it). 

So perhaps the ultimate model for describing authentication is 

Some things you have (with various proof mechanisms) 


Lance said...

Only one challenge I can think of with that convergence, and its admittedly from an American context.

In the US, you cannot legally be compelled to provide something you know. Its the 5th amendment right of protection against self-incrimination.

Current legal jurisprudence in the US states that the 'are' and 'have' factors are not subject to that protection. That is one of the innate challenges with biometric authentication.

grandpa blair said...

The Nyami device has a cool factor to it that other biometric mechanisms lack however the fundamental flaw in biometrics is enrollment. How do you really know who belongs to that Iris, fingerprint or Nyami?

I agree that something you have provides stronger authentication than using something you know. We use government issued ID's. We are able to authenticate the ID document and verify that the consumer is the person depicted on the ID effectively authenticating what you have and what you are.