Name Constraints, was Re: [caops-wg] Re: ca signing policy file

[Frank Siebenlist]

Mike Helm wrote:
> Frank Siebenlist writes:
>   
>> With your proposed scheme, any "trusted" CA in Italy, Germany, even 
>> Holland..., would have the theoretical opportunity to issue a 
>> certificate that would impersonate the director of Berkeley, NCSA, 
>> Livermore, Los Alamos... and we would have no way to enforce any policy 
>> in real-time that could prevent it.
>>     
>
> Of course, if you think the names in a certificate have an inherent
> meaning, 

The idea of using unique but meaningless names in the certs is a good 
one, but it doesn't solve the issue really...

It definitely makes the initial vetting easier, but after you have 
assigned some uuid to some key, and that key-holder happens to be the 
lab director, then it is no longer a meaningless name for subsequent 
authorization decisions. It then becomes important that no other CA will 
issue that same uuid to the key of a different key-holder, which should 
be "enforced" either by "Thy shall not..." policies or by adding the CA 
somehow in the equation for real-time enforcement.

> and you don't use the issuer in the evaluation, you are stuck.
> This is the defect in the grid authentication scheme. Trying to fix
> this with name constraints is backwards in my opinion.
>   

Are you suggesting that we should keep the CA always with the DN for all 
the authorization decisions?
(Essentially pushing the policy enforcement of name+CA to the 
authorization stage and throwing-in the towel as far as the pkix/x509 
global-naming dream is concerned...)

> If this acceptable to all our end user organizations, we should happily 
> adopt the web-browser trust model with paper CA policy statements... and 
> I'm serious here.
>   
>
> Just what do you think we have now?
>   

That is the real question then: Can the EGEE/FusionGRID/OSG/TeraGRID/??? 
live happily with the "Thy shall not..." model?
If so, life is easy, no need for those pesky ca signing policy files, 
and let's move on...
If not, or maybe not, or sometimes not, should we move to a model where 
the CAs remain in the authorization picture and asserted names should 
always be considered in the context of the issuer?


-Frank.

-- 
Frank Siebenlist               franks at mcs.anl.gov
The Globus Alliance - Argonne National Laboratory