[TLS] OBC and logout (Re: TLS-OBC proposal)
Nico Williams <nico@cryptonector.com> Thu, 08 September 2011 21:56 UTC
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Date: Thu, 08 Sep 2011 16:58:41 -0500
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From: Nico Williams <nico@cryptonector.com>
To: Dirk Balfanz <balfanz@google.com>
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Cc: tls@ietf.org
Subject: [TLS] OBC and logout (Re: TLS-OBC proposal)
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Also note that here the client can make logout work better: the server can't accept the old cookies if the client destroys the corresponding OBC's private key. Sure, the server could loosen its rules and accept such cookies anyways, but it'd be opening itself to a big vulnerability unless it greatly limited what it will allow clients presenting such cookies to do (i.e., the server could allow such cookies only for post-logout tracking. If we know which cookies are channel bound to OBCs then the client can destroy those cookies when the corresponding OBCs' private keys are destroyed. So then the only way channel bound cookies can be used for tracking would be if they leaked. This would be almost as strong a logout semantic as you'd get with, say, REST-GSS. Strong enough for me. Nico --
- [TLS] OBC and logout (Re: TLS-OBC proposal) Nico Williams