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RE: Dangling phase 2 SAs (was RE: issues from the bakeoff)

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>[SNIP
> > 
> > The issue of dangling phase 2 SAs seems to have created a camp
> > that believes that when a certificate is revoked, a compromise
> > has occured, and therefore any phase 2 SAs created under the
> > phase 1 SA with a now revoked certificate as the authentication 
> > mechanism should be removed.  
> > 
> > Point 1: Compromise? What compromise?
> > 
> > There are many reasons to revoke a certificate that in no way
> > invalidates authorizations that certificate performed prior to
> > the revokation. For example, an employee leaves a company, the
> > company revokes that employees certificate. Actions that employee
> > took while still employed are still valid. 
> 
> I don't think system administrators would agree with you here. If
> an employee leaves a company, he/she is supposed to leave behind 
> all access to that company's assets. The longer SAs are left up
> after this  point, the greater the exposure.  
> 
> Yes, it's a different kind of compromise that key material or
> authentication, but it's a compromise none the less.
> 
Hmm, to make sure I understand, a contrived example:

. Gary the GVPN administrator has a company issued certificate
  giving him the privilege to set up a secure link.

. He sets up a GVPN link using IPsec/IKE between his company and
  Widget Inc. using his company issued certificate for 
  authorization.

. Gary then leaves the company. The company issues Gary's 
  certificate in a CRL.

. Widget Inc. is paranoid (a good thing) and assumes, upon
  getting the new CRL, that Gary left for evil reasons and 
  before he left, had oppertunity to get key information. 
  What does Widget Inc. do? Dump all the SAs that were in
  any way under Gary's control to reduce possible exposure.

This makes sense - maybe I'm changing my mind :-) . But, on the other
hand, if Gary's certificate just expired, I think that does not
invalidate what was authenticated with the certificate before the
certificate expired. (A document signed before the signature key
certificate expired still has a valid signature long after the
signature certificate expires.)

So, IMHO, dangling phase 2 SAs are ok (and may even be needed) but,
implementers may wish to create a way to get rid of phase 2 SAs based
upon some types of change of validity of authentication in phase 1.

- -Michael Heyman

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