> On 29 Oct 2014, at 10:17 am, John Curran <[email protected]> wrote:
> 
> On Aug 11, 2014, at 11:58 AM, Tim Bruijnzeels <[email protected]> wrote:
>> ...
>> The *one* thing I (and I believe we..) challenge is whether the an 
>> overclaimed resource should invalidate a complete certificate, instead of 
>> invalidating just the resources at hand, but allowing the remainder.
>> ...
>> The following two we may be able to mitigate technically, because we are 
>> dealing with co-operating parties:
>> @1 There is a mis-timing in certificate shrinking in a transfer between 
>> co-operating parties.
>> @2 There is a mis-timing in the parent publishing a cert with extended 
>> resource, and issuing it to the child, and the child using those resources 
>> in turn.
>> 
>> But this is the one that has me scared. It is not the issuing CA being 
>> sloppy, it’s a problem between them and *their* parent:
>> @1 The *grand*-parent shrinks the *parent* certificate without the parent 
>> knowing about this, and some of these resources appear on the, now 
>> overclaiming, child certificate. The grand-parent and parent are not 
>> involved in an active transfer process. They may not agree that the resource 
>> in question should be removed, or the grand-parent may have shrunk these 
>> resources in error.
>> 
>> By rejecting the overclaiming child certificate completely I think we are 
>> being too harsh, or pedantic even. We know better, so we are just not going 
>> to trust this one. But.. there is a very real possibility that we actually 
>> *do* know better than the issuing CA at this point. So, what exactly is the 
>> problem with accepting the remaining resources? i.e. the intersection 
>> between the parent certificate’s resources and this certificate. We know the 
>> context, this evaluation is very easy and well-defined. If the CA really 
>> intended that the remaining resources should not be tied to the certificate, 
>> they would have revoked. If the grand-parent really intended that those 
>> resources should not be certified anymore, they would have removed them as 
>> well.
> 
> I'm certain there is a simple answer for this question, but it alludes me
> at the present time...
> 
> Given the risks of full resource list invalidation due to overclaiming, why
> aren't distinct certificates used for distinct resources?  If this is not 
> practical in general, wouldn't it at least be prudent to "groom" resources 
> that are going to be transferred into their own certificate so that the rest 
> of the resources held by the original child are not put at validation risk 
> (if a coordination error were to occur in subsequent transfer processing)
> 

If I understand your note here, you are suggesting that the CA issues a new 
cert for the to-be-transferred resource and revokes and reissues the original 
"omnibus" cert to have all the resources minus the to-be-transferred resource. 
Yes? But does not this exacerbate the very problem about over-claiming 
subordinate certs? Any subordinate certs of the shrunken "omnibus" cert that 
still include the to-be-transferred resource are now completely invalid. I may 
not be following your suggestion here, but I just can't see how this makes it 
"better".

regards,

Geoff
 







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