Subject: Re: 3280bis: CRL validation

From: "Denis Pinkas" <[email-masked]>
Date: Tue, 21 Jun 2005 15:50:49 +0100

David,

I could use the same wording as you use:

" You can repeat as many times as you like that DNs need to be globally unique 
but it still won't become true. 

Other people (e.g. Santosh, Stefan, Lucien) have pointed this out to you and 
yet you continue to repeat the same false claim. No matter how many times 
you will assert this claim, you will not be able to make it true".

Some please, for the future, keep trying to avoid this kind of wording.

Have said that, let us come to the core of the issue.

When we started this WG (and I was in the meeting room), we said that 
we take X.509, but we do not take X.500. In PKIX, we do not need X.500, 
so that X.509 can work.

We do not consider that a unique DIT exists in RFC 3280. Make a search 
for "DIT" and you will find thes three letters nowhere.
 
As Stefan pointed out, there are many different DITs, in teh contxt of 
RFC 3280 as many as there are CAs in the world.

In RFC 3280, we do use the *syntax* of a DN defined in X.509, but we always 
said that names are only unique for the CA that has assigned them.

"The DN MUST be unique for each subject entity certified by the one CA 
as defined by the issuer name field".

There is no other constrain in RFC 3280.

I would believe that some people originally thought that the only way 
to make RFC 3280 secure was to have globally unique names, which is not
a practical case and mentioned nowhere in RFC 3280.

The good news is that it is indeed possible to have security without making 
the (false) assumption that names issued by CAs are globally unique.

The bad news may be that some people built their systems making that (false) 
assumption and thus implementations that would be built on that assumption 
would be vulnerable to some attacks.

Denis

>> David,
>>
>>> Stefan Santesson wrote:
>>
>>>> Show me the paragraph in X.509 or RFC 3280 that says that the subject of
>>>> a compliant certificate MUST have a name that corresponds to a globally
>>>> unique entry in the DIT.
>>>
>>> I really don't want to get involved in a discussion about whether it was
>>> a wise or unwise decision for X.509 to be designed around the assumption
>>> that name collisions will not occur, but here are some quotes from X.509
>>> and X.501:
>>
>>> X.509, Clause 3.2 (Directory model definitions): The following terms are
>>> defined in ITU-T Rec. X.501 | ISO/IEC 9594-2: f) distinguished name;
>>
>>> X.509, Section 7 (Public-keys and public-key certificates): NOTE 1 –
>>> Although the CAs are unambiguously defined by a distinguished name in
>>> the DIT, this does not imply that there is any relationship between the
>>> organization of the CAs and the DIT.
>>
>> In X.500 there is a single "DIT", whereas in X.509 there is a DIT per CA.
>> Full stop.
>
>
>Denis,
>
>You can repeat this as many times as you like and it still won't become 
>true. You keep insisting that X.509 follows a different model than 
>X.500. But,
>
>(1) X.509 states that it uses the naming model from X.501 and 
>specifically states that names are unambiguous (nowhere does it say 
>unambiguous relative to ....)
>
>(2) X.501 (in clause 1, Scope) states that the concepts defined in that 
>document are used in the other documents in the X.500 series, including 
>X.509.
>
>(3) The people who wrote these documents insist that they really meant 
>that names in X.509 are unambiguous, and are not simply unambiguous 
>relative to the issuing CA.
>
>
>People have pointed this out to you over and over again in multiple 
>forums and yet you continue to repeat the same false claim. No matter 
>how many times you have asserted this claim, you have never be able to 
>point to text in the standards to support your claim.
>
>In X.509, not Denis' mind, names are unambiguous.
>
>You can argue as much as you want about how X.509 SHOULD HAVE been based 
>on locally distinct names, but there is a difference between "should 
>have" and "did".
>
>If you are going to continue to claim that X.509 WAS written around the 
>assumption that naming is local, then please explain:
>
>(1) Why the text states that names are unambiguous without indicating 
>that names are only unambiguous within a certain scope.
>
>(2) Why all of these rules that you have noted would need to be enforced 
>in order to ensure security in an environment in which names are only 
>distinct with respect to the issuing CA were not included in the standard.
>
>(3) Why the people who actually developed and wrote the standard claim 
>that X.509 was written based on the assumption that names are globally 
>unambiguous (just as the standard states).
>
>Dave
>

Regards,

Denis Pinkas

---

From: "David A. Cooper" <[email-masked]>
Date: Tue, 21 Jun 2005 10:04:41 -0400

Denis,

Yet again your message contains nothing but unsupported claims. You 
claim that "[i]n RFC 3280, we do use the *syntax* of a DN defined in 
X.509, but we always
said that names are only unique for the CA that has assigned them." 
Where is your support for the claim that the PKIX WG decided to diverge 
from X.509 in such a fundamental way? The entire PKIX mail list archive 
seems to be available on-line, so if what you are saying is true, you 
should be able to present some evidence.

Besides, up until now you have been claiming that these rules applied to 
X.509, now you are saying that this only applies within PKIX. Which is it?