Subject: Re: OCSP and German Law

From: "Hesse, Johan" <[email-masked]>
Date: Thu, 24 Feb 2000 16:32:26 +0100

Hello!

I agree to Stefan, I bet a box of beer that the "validity model" in the
German Law won't change.

We accompanied TrustCenter which are conform to German Law and we saw that
this validity model has an advantage (maybe this is the rational of the
model). Since everyone seems to be unhappy with this validity model lets
mention the advantage to the honour of the good old law.
But please don't flame me, because I'm sure that there are other (better?)
possibilities. 

The advantage is more or less of legal and/or organizational nature. If the
CA signs a certificate, the PSE (e.g. your smart card with your *private*
key) has to be delivered in a secure way to the owner. 

In technical terms the certificate is almost valid (but not in legal terms).
But the PSE hasn't handed out to the owner yet, - with all possibilities of
abuse (I know there are ways to handle it in another way). But if you wait
until the owner proofs that he received the PSE, to say the certificate is
valid you avoid this insecure time gap. The validation is manifested by
publishing the certificate.

So I hope you see the rational of this validity model.

   Cheers,

               Johan

P.s.: I wait if somone wants to bet. I propose we drink the beer together, -
lets say at the CeBit 2001.

> **************************************
> Johan Hesse
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> Security Networks AG     
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---

From: Simon Tardell <[email-masked]>
Date: Thu, 24 Feb 2000 17:04:40 +0100

My comments below.

Hello! 

I will not challenge your bet, but: This is not a good reason to mandate
that a validation authority must know if a certificate was ever issued. To
make sure that the certificate is not valid between the point in time where
it is issued and where the corresponding token is confirmed received by the
intended end-user you simply put it on-hold (revoke it with reason code
on-hold) until such confirmation is received. This is in my mind a rather
good way of using "suspension" (as compared to some of the more construed
scenarios we've been hearing). It was brought up that the German law does
not allow suspension. This is almost true -- but a certificate that has been
issued but not yet entered into the directory (SigG) is in fact suspended,
so for this exact purpose it seems ok. 

I think the point made by earlier by Andreas makes a lot of sense:

Another point is that the compromise of a CA key may be a very seldom event
but the potential cost, even with a desaster plan in place (anyone heard
about one from any CA?) it may be desirable to have simple technical
fallback position.

If the CA keys are compromised it can be prohibitingly expensive to replace
all certificates, especially since smart cards are mostly off-line. If there
is an independent notary service (which the directory (SigG) essentially is)
that can vouch for that a certificate was (or was not) issued before the
compromise of the CA keys, the tokens can be continued to be used. And, I
guess, there can be any number of "backup" directory (SigG) services,
improving reliability.

Simon.

Simon Tardell, Software Architect, iD2 Technologies 
[email-masked],  <http://www.id2tech.com/>
http://www.iD2tech.com/ 
voice +46 8 7755225, cell +46 70 3198319, fax +46 8 7267912 
European IT-prize grand winners 1998 --  <http://www.it-prize.org/>
http://www.it-prize.org 
AU-System Group Swedish IT-company of the year 1999

---

From: "Hesse, Johan" <[email-masked]>
Date: Fri, 25 Feb 2000 12:38:54 +0100

> -----Ursprüngliche Nachricht-----
> Von:	Stefan Kelm [SMTP:[email-masked]]
> Gesendet am:	Freitag, 25. Februar 2000 10:40
> An:	[email-masked]
> Betreff:	Re: OCSP and German Law
> 
> Johan,
> 
> According to the (still internal) drafts of the new law it won't change at
> all.
> 
> I think this is pretty plausible. However, using this model the directory
> is much more burdened with security issues than usual. Denial-of-service
> attacks against the directory become much more crucial, IMHO. If someone
> doesn't want your certificate to be validated (e.g., because you digitally
> signed an order to buy one million new shares of that interesting company
> and the attacker doesn't like that) he shuts down the directory server
> for a while.
> 
> 
	[Hesse, Johan]  Yes, - that's the point. But I didn't say that the
model was the only one or rather the best.
	But the denial of service attacks seems to be independent from this
model (?).

	For contract partner it's of particular importance that they can
check the status of the certificates within some minutes (see your example
of the financial transaction). So the DIR has to be available at any time.
In practice it will be the weak point. 

	Cheers, Johan