Subject: [OAUTH-WG] Fwd: EncryptedAssertion in draft-ietf-oauth-saml2-bearer-21

From: Brian Campbell <[email-masked]>
Date: Mon, 20 Oct 2014 10:58:30 -0600

I received the below over the weekend and, although [email-masked] is cc'd,
it didn't post to the list - I assume because [email-masked] isn't
subscribed. I thought I should send to the WG list so folks are aware.

I don't believe EncryptedAssertion should be supported, for three main
reasons.

1) It is very late in the document process, which is currently in IESG
review. It's too late, really, for a change like this.
2) It adds complexly that's not necessarily needed as the Subject and/or
individual attributes of a SAML Assertion can be encrypted to the
authorization server
3) It greatly increases the risk that usage of this profile be vulnerable
to attacks such as those described in
http://www.nds.ruhr-uni-bochum.de/research/publications/backwards-compatibility/
whereas having the encrypted parts appear under a signature (and not
attempting decryption if the signature validation fails) mitigates the risk

---------- Forwarded message ----------
From: <[email-masked]>
Date: Sat, Oct 18, 2014 at 4:05 PM
Subject: EncryptedAssertion in draft-ietf-oauth-saml2-bearer-21
To: [email-masked]
Cc: [email-masked], [email-masked]

Seems sec 3, list item 10 (p.8) mentions that encryption per SAML2 is
allowed, but I think it would be helpful to call out that specifically
EncryptedAssertion is allowed. Mentioning EncryptedAssertion as valid
possibility in secs 2.2 and 2.3 would also help.

The Privacy Considerations section should mention use of EncryptedAssertion
to protect against eavesdropping by intermediaries that handle assertions
(e.g. OAUTH Client which gets it from STS and passes it to AS).

Cheers,
--Sampo