Sunday, April 24, 2011

pseudonym in SAML 2.0

I was reading the paper on SAML 2.0 Technical Overview For a complete understaning of SAML, read the SAML Technical Overview

While describing the pseudonym it was told that two user identities can be integrated by the IdPs. For example, I have a gmail account narasimmanr@gmail.com and a yahoo account narasimmanr@yahoo.com. I want to link these two accounts. How will I do this?


  1. I will login to one of the accounts, say yahoo.

  2. Send a message to Yahoo to link my gmail id

  3. Yahoo will send a mail to Gmail stating that narasimmanr@yahoo.com wants to link narasimmanr@gmail.com


    • Since yahoo must know that both the accounts are owned by the same individual


  4. Gmail will send a mail to narasimmanr@gmail.com for permission

  5. when I login to narasimmanr@gmail.com I see this mail and gives the permission.

  6. Gmail will send the permission to Yahoo

  7. Both accounts are linked



The happy path scenario works very well.


But the alternate path is where the doubt arises.

If narasimmanr@gmail is not owned by me. The real owner will look at it and rejects this. No problem. Gmail will send a rejection request to Yahoo and Yahoo replies back to me saying that the linking has failed.

If the other person, knowingly or unknowingly, accepts the linking. Now, I can reach out to his google apps through my Yahoo id and all other sites that trusts google. Same is applicable to him/her as well.

Question is how one can avoid this?

In the correct scenario, the delinking will also work. In the other scenario, if I delink the two accounts, will there be a confirmation from other account also? I think this is not required since once the account is linked both the IdP thinks that it is a single user.

Any thoughts on this?

1 comment:

VenuDeevi said...

Good blog on SAML 2.0 and its trust between yahoo and gmail... However you have raised tricky scenario... need to think a deep to answer your question….