[caops-wg] Name Constraints - attempt at framing issues

[David Chadwick]

Cowles, Robert D. wrote:
>  
> 
> 
>>1) What CAs do we wish to consider as potential issuers for our  
>>community? Is it just "Grid CAs" (by that I mean CA we can 
>>reasonably  
>>except to adhere to best practices as specified by GGF WGs) or do we  
>>want to also consider CAs that we have no reasonable expectation of  
>>being able to impact their policies or procedures (e.g. commercial  
>>CAs) as potential issuers for our community as well?
> 
> 
> I think that if we are successful, all this will be used in ways
> we can't now imagine or, in the future, control.  To me, the idea of 
> depending on CA's to issue certificates for DNs that are globally
> unique is just asking for trouble.  Administrative controls to 
> keep the namespaces separate are clearly not good enough. The signing
> policy file is a technical control but it still seems pretty weak.
> To me, the thing that is unique is (DN + CA) and the function of the

Bob

dont you think it is a little optimistic to assume that a TTP that 
cannot be trusted to issue unique names to its clients, can be trusted 
to get a unique name for itself?

regards

David


> CA is to try it's best to not issue a cert with the same DN to 
> different people. I would be happy if they can do just that and I
> think it unreasonable to believe that the DN is unique in the 
> universe (or even a small section thereof).  The signing policy
> files basically allow us to say - given this DN, it should have been
> issued by that CA - and as far as I can see, it's because the CA
> is't stored in the gridmapfile (and maybe it's not there because
> the DN was suppoed to be unique - but that was8-10 years ago, and
> we know better now).
> 
> 
>>2) Do we believe that during normal operation the CAs indicated in  
>>the response to the first question have policy that will result in  
>>their issuing globally unique names and will reliably follow that  
>>policy?
> 
> 
> I think it's not true in "normal operation" and that any moderately 
> talented attacker would be able to generate a condition outside
> of "normal operations" and get *someone* to issue a certificate
> with any DN they chose.
> 
> 
>>3) If a CA is compromised, given currently implementations, 
>>this will  
> 
> 
> (my comments here were in an earlier email).
> 
> 

-- 

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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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