Subject: RE: Antwort: Re: Real-time Certificate Status Facility for OCSP - (RTCS)

From: "Hallam-Baker, Phillip" <[email-masked]>
Date: Wed, 5 Feb 2003 05:50:17 -0800

> My response to Simon addresses this issue, i.e., German law seems to 
> have mandated a solution to a problem that is not technically 
> justified, given the alternatives. PKIX is not in the habit of 
> setting standards to accommodate national level laws that may be ill 
> advised.

It seems somewhat unusual to see a national law mandate a particular
technology. Legislators are usually anxious to avoid specifying
implementations.

The statement 'we must do X' is preceeded by a requirement. So what is
it that the law actually says, does it really say you must do X or does
it actually specify the requirements?

The OnHold requirement appears to me to be an authorization requirement,
not an authentication requirement. It is in any case possible to address
the requirement in other ways.

The CA compromise requirement is somewhat strange. If a CA key is 
compromised the end entity certs signed under that key are compromised.
I don't think that OCSP is going to help since the signing key of the
OCSP responder would normally chain to the same root - unless we are
going to deploy a second set of roots of trust.

Furthermore which CA key are we talking about here? The root of trust
or the intermediate CA that signs the end entity certificate?

If the root of trust is compromised but not the intermediate you simply
sign yourself a new root of trust. If the intermediate is compromised
the end entity cert is compromised regardless of what opinion German
law might have or appear to have on the matter.

	Phil

---

From: "Simon Tardell" <[email-masked]>
Date: Thu, 6 Feb 2003 12:29:41 +0100

> compromised the end entity certs signed under that key are 
> compromised. I don't think that OCSP is going to help since 
> the signing key of the OCSP responder would normally chain to 
> the same root - unless we are going to deploy a second set of 
> roots of trust.
> 
> Furthermore which CA key are we talking about here? The root 
> of trust or the intermediate CA that signs the end entity certificate?

The CA that signs the EE certs.

> If the root of trust is compromised but not the intermediate 
> you simply sign yourself a new root of trust. If the 
> intermediate is compromised the end entity cert is 
> compromised regardless of what opinion German law might have 
> or appear to have on the matter.

"German OCSP", that is OCSP as modified by the SigI (German industry
interoperability specification for systems based on SigG/V) is not just
a revocation responder answering on delegation for the CA. It is an
independent notary. That is, it vouches for that the certificate existed
at a certain point in time. It is also independent from the CA it
answers for.

It does indeed solve the problem, but at the cost of inventing mechanism
and protocols that the rest of the world does not know about. I have my
doubts of the actual robustness of the solution as well.

Simon

Simon Tardell, cell +46 70 3198319, [email-masked]