[OGSA-AUTHZ] Implementations

David Chadwick d.w.chadwick at kent.ac.uk
Sat Mar 22 10:32:38 CDT 2008

Hi Tom

we do a dis-service to people by specifying a standard which we know to 
be deficient beforehand. This will cause even more delays in trying to 
rectify it (consider for example the OGSA Authz SAML spec, GFD 66, which 
  was only found to be deficient after practical trials, and how long it 
has taken to produce replacements).

My suggestion would be to raise a ballot comment now on the current 
OASIS draft, along with a proposed solution, so that this can be taken 
into account in the revision. If the process is anything like IETF or 
ISO it should not cause too much of a delay.



Tom Scavo wrote:
> On Sat, Mar 22, 2008 at 5:44 AM, David Chadwick <d.w.chadwick at kent.ac.uk> wrote:
>>  ...the inclusion of a "certificate" needs more elaboration. The
>>  inclusion for example of a user's public key certificate proves nothing
>>  more than the presence of a DN does, since it is publicly available and
>>  an untrustworth grid SP could send any PKC it wished, just as it can
>>  send any DN it wished. Therefore one needs to specify the properties of
>>  the certificate that are being transferred, which is, that the user is
>>  delegating to the grid SP to act on its behalf. A proxy certificate
>>  would do this, as would an attribute certificate.
> I totally agree.  Of course this requires a new attribute request
> handler at the Shib AA but then a new handler is required for a bare
> DN as well, so there's no additional penalty.  I don't know that much
> about the VOMS AA, but I'd be surprised if handling a full certificate
> turned out to be much of a problem for VOMS.
> We have a dilemma, however.  A formal ballot is currently underway to
> promote the OASIS SAML V2.0 Deployment Profiles for X.509 Subjects to
> Committee Specification status.  I fully expect this ballot to
> succeed.  The next step after Committee Specification is OASIS
> Standard (but this last step requires three attestations, which is
> unlikely).
> If we introduce a normative change to the profile such as we've been
> discussing, we essentially start over.  Presumably the profile could
> travel faster through committee this time around since the bulk of it
> has already been vetted, but a significant delay is inevitable.
> The other alternative is to specify this new extension of
> saml2:BaseIDAbstractType in our Attribute Exchange profile and leave
> the OASIS profile alone, flawed as it is.  A third alternative is to
> do nothing.
> I'm not sure what to recommend.  I'll let others comment on the
> appropriate course of action.
> Tom
>>  Tom Scavo wrote:
>>  >
>>  > Instead of *requiring* a DN, the name identifier in the query should
>>  > be generalized to accommodate the entire certificate (without
>>  > excluding the possibility of a naked DN in those situations where it
>>  > is warranted).  This can be done using <ds:KeyInfo>, something like
>>  > this:
>>  >
>>  > <saml:Subject>
>>  >  <saml:BaseID xsi:type="KeyIdentifierType">
>>  >    <ds:KeyInfo>...</ds:KeyInfo>
>>  >  </saml:BaseID>
>>  > </saml:Subject>
>>  >
>>  > where KeyIdentifierType is defined as follows:
>>  >
>>  > <complexType name="KeyIdentifierType">
>>  >  <complexContent>
>>  >   <extension base="saml:BaseIDAbstractType">
>>  >     <sequence>
>>  >       <element ref="ds:KeyInfo"/>
>>  >     </sequence>
>>  >   </extension>
>>  >  </complexContent>
>>  > </complexType>


David W. Chadwick, BSc PhD
Professor of Information Systems Security
The Computing Laboratory, University of Kent, Canterbury, CT2 7NF
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Email: D.W.Chadwick at kent.ac.uk
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