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

[Frank Siebenlist]

When you say "name collisions", you must be referring to either 
compromised CAs or errors as name collisions should not occur...

By using both the Subject's DN as well as the CA in the authorization 
policy, you're essentially negating the ability of the PKI to define 
global names: if you believe in the pkix/x509 religion then after the 
path validation, the CA falls out of the equation.

Now Mike's idea of using some random names for subjects is good but 
doesn't solve the problem as it would still allow any "trusted" CA to 
bind a different key to the same random-name.

Maybe random names for subjects should be used together with name 
constraints.

In other words, the Subject's DN should start with an identifier that 
essentially identifies the administrative domain in which the names are 
issued, e.g. \DOMAIN=ESNET.NET, followed by a 
\CN=abbf16d0-3b5f-11da-8cd6-0800200c9a66
In that way, a CA could be restraint to issue random names within a 
certain domain.

-Frank.


Cowles, Robert D. wrote:
> The name constraints are important because the gridmapfile doesn't
> contain the CA that issued the DN, only the DN. Therefore, name
> collisions can occur and cannot be detected.  If we make sure 
> that the middleware includes a check of the CA when it compares
> on DN, then what you say is correct.
>
>   
>> -----Original Message-----
>> From: owner-caops-wg at ggf.org [mailto:owner-caops-wg at ggf.org] 
>> On Behalf Of David Chadwick
>> Sent: Wednesday, October 12, 2005 10:57 AM
>> To: helm at fionn.es.net
>> Cc: Von Welch; Tony J. Genovese; 'Frank Siebenlist'; 
>> 'CAOPS-WG'; 'Olle Mulmo'; 'Joni Hahkala'; 'Jules Wolfrat'; 
>> 'Ron Trompert'
>> Subject: Re: Name Constraints, was Re: [caops-wg] Re: ca 
>> signing policy file
>>
>> Mike
>>
>> this is a very interesting viewpoint. What you are saying, if 
>> I put it 
>> another way, is that everyone can have a completely random name, its 
>> irrelevant what it actually is, as long as the user can 
>> authenticate to 
>> that name (via signing something whose signature validates with the 
>> certificate containing that name) and then as long as the 
>> authorisation 
>> infrastructure can reliably get the set of attributes that 
>> are bound to 
>> the same name, then correct authorisation can be performed, 
>> regardless 
>> of the name of the user. In which case name constraints are 
>> irrelevant. 
>> I would agree with that
>>
>> regards
>>
>> David
>>
>> Mike Helm wrote:
>>     
>>> Von Welch writes:
>>>
>>>       
>>>> I meant to say that unless NameConstraints are adopted by CAs in  
>>>> general (which probably means both "Grid CAs" as well as all the  
>>>> various software packages our communities use to generate  
>>>> certificates), we still need something like current ca signing  
>>>> policies (i.e. relying party-specified name constraints).
>>>>         
>>> I don't think name constraints, in general, no matter who does them,
>>> are worth the slitest amount of our attention.  They don't solve
>>> any problem that anyone actually has. (I think this is one reason
>>> rfc 2459 name constraints took so long to get any  support.)
>>>
>>> This is particularly true in grid environments where the 
>>>       
>> authentication
>>     
>>> and authorization has been separated.  
>>>
>>> What we do need, just like in any other pki, is some way of stating
>>> whether or not a CA is trusted, and for what purposes (cert types).
>>> If "purposes" includes naming, fine, but I don't think that
>>> should be its primary or only method.    One purpose might
>>> be "any" or "none": A scheme like that would
>>> be very useful to the middleware: you can distribute a large
>>> number of CA signing certs and make it easy for the 
>>> relying party to configure the CA trust list.  (Most of our 
>>> current CAs are grid-only.)
>>>
>>> The current signing policy file is useful, in that it puts a brake
>>> on what is going to be trusted, but the only decision it allows
>>> is based on naming, which I contend is useless, and forces people
>>> to deal with an inherently clumsy syntax that has been 
>>>       
>> dis-optimized.
>>     
>>> A side effect is that it places a huge emphasis on naming in Grids,
>>> which is a waste of everyone's time.  We should be free to use 
>>> whatever naming is appropriate and not jam ourselves into narrow
>>> naming rules so that we don't disturb the delicate naming policy
>>> rule distributed everywhere.  Since names in grids have no inherent
>>> meaning and we have authorization schemes to enroll and control
>>> privileges on successful authentication, the name 
>>>       
>> constraint in Grids
>>     
>>> doesn't add anything.  I also think this is functioning as a 
>>> market inhibitor, in that CAs that don't fit this pattern such
>>> as commercial CAs or other schemes are kept out of the business.
>>>
>>>
>>>       
>> -- 
>>
>> *****************************************************************
>> David W. Chadwick, BSc PhD
>> Professor of Information Systems Security
>> The Computing Laboratory, University of Kent, Canterbury, CT2 7NF
>> Tel: +44 1227 82 3221
>> Fax +44 1227 762 811
>> Mobile: +44 77 96 44 7184
>> Email: D.W.Chadwick at kent.ac.uk
>> Home Page: http://www.cs.kent.ac.uk/people/staff/dwc8/index.html
>> Research Web site: http://sec.cs.kent.ac.uk
>> Entrust key validation string: MLJ9-DU5T-HV8J
>> PGP Key ID is 0xBC238DE5
>>
>> *****************************************************************
>>
>>
>>     
>
>   

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