Re: secondary certs and names (was: Re: Secondary Certificates and 0-RTT)

Hiya,

On 12/07/18 16:25, Ilari Liusvaara wrote:
> On Thu, Jul 12, 2018 at 03:53:02PM +0100, Stephen Farrell wrote:
>>
>> (For some reason the other thread made me wonder about
>> this...)
>>
>> This may be handled already and even if not is probably
>> not a real-world problem, but do we know what happens if
>> the subjects/SANs from primary and 2ndary certs combined
>> result in there sorta being no valid names due to
>> excludedSubtrees in one nixing the names from the other?
> 
> I do not think certificates are supposed to interact with one another,
> so ExcludedSubtrees can not nix names from the other.

I guess that might be an ok answer too. OTOH, it's a bit
confusing if we can have one h2 session that is associated
with example.com via cert1 and via cert2 with 'example.net and
excluded=example.com'

If there's no possibility for confusion to arise that'd be
fine but I'm not sure.

> 
>> I wonder if there are any other PKIX oddities that also
>> ought be noted? Might be worth a check of this draft
>> vs. 5280 with that in mind, as I don't recall PKIX (despite
>> it's longevity;-) considering the semantics of sets of
>> certs, which is what's in play here I guess.
> 
> Letting certificate chain affect the interpretation of the leaf
> certificate is probably a bad idea. And letting certificate chains
> affect interpretation of each other is much worse idea.
> 
> Besides the other problems, certificates affecting each other tends to
> rather easily lead into intractable (not known to be efficiently
> solvable) computational problems trying to make sense of what the
> mess actually means. :-)

Yep. It would be a mess. (Frankly though x.509 is a mess already:-)
But I hope the secondary certs draft doesn't cause and/or avoids
that mess.

Cheers,
S.

> 
> 
> -Ilari
> 
>