Enterprise Signing in OAuth

Session: Tuesday, Session 2, Space I

Conference: IIW 10 May 17-19, 2009 this is the complete Complete Set of Notes

Brian:  "I'm really happy with Oaut2, except for the signing...  Can we take section 5.3 of the spec and set it on fire?"



Problems seen:


• HMAC covers the situation where people don't want to do SSL, but requires the whole ugly key management thing.  Brian proposes (with a long list of others interested) that we need public key signing.


• The signing is not extensible, you can't add additional fields to the signature.  This seems to be a problem in the current spec.


• New protocol substrates.


• One signing choice doesn't seem enough.  Extensibility seems key here, can we do this with some form of discovery?



Proposed fixes:



• Create a JSON blob we want signed.
    - 
  • an example...  does not require reconstruction of the string to be signed
   
  • BUT how do you verify the signed stuff is part of the request?
   
  • ALSO not great: duplication of data.

• We need key versioning

  • Needs key discovery
   
  • Can use something liek https://<app>.appspot.com/.well-known/oauth or some such.
       
  • This might not work for folks that are white label, because there isn't a separate URL for all the entities that need to be discovered.
   
• There is a google group for the OAuth Key Discovery spec.  See Brian's copy of the slides.
   
• It's worthwhile to join the OAuth2 mailing list to comment on this.
   
• This is a big discussion topic, I don't type that fast.
   
• XKMS is again, good reference reading for this.



Discussion:


• How does it work with firewalls -- in and out...

• XMLDSIG is very similar to this, it would be worthwhile to learn from that.  Also CMS (Crypto Message Sig).
• Does have the whole PKI problem.


• Can we solve this with SSL?  SSL with client certs?  Maybe...
   
  • Much discussion here about how key excahnge and key management should work.


• Comment -- If you want to sign arbitrary parts of an HTTP request then use SAML.  you don't really want to duplicate that here.

• Need to make sure we get the key exchange right, if you try to put it in here people will get it wrong.




•   KeyID/key discovery.
   
  •  comment: see XKMS for related reading.
   
  • keyID probably belongs in the envelope and not the payload (from his modified example.