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RE: German Law and OCSP
Hi Michael,
- The requirements you have specified could be met by using
standard OCSP and requiring the VA to send over the full cert
hash in the response.
- If a CA cert signing key has been compromised, I would
treat everything issued by the CA as suspect - you would open
yourself up to too many attacks - it isn't worth it to try and
save the certificates that were legitimately issued.
Regards,
Ambarish
---------------------------------------------------------------------
Ambarish Malpani
Architect 650.567.5457
ValiCert, Inc. ambarish@valicert.com
1215 Terra Bella Ave. http://www.valicert.com
Mountain View, CA 94043-1833
> -----Original Message-----
> From: Michael Herfert [mailto:michael.herfert@gmd.de]
> Sent: Friday, February 25, 2000 7:14 AM
> To: Denis Pinkas; ietf-pkix@imc.org
> Subject: Re: German Law and OCSP
>
>
> Hello Denis and all,
>
> Denis Pinkas wrote:
> > Besides the wording, the question was to understand the rational of
> > the model. The question is still pending ...
>
> The standard X.509 model does not satisfy the requierements
> of the german
> law. So there was a need for a new model. The important
> paragraphs are:
>
>
> §13(5): "The validity of the certificates issued by a
> certification
> authority shall remain unaffected by the withdrawal or
> revocation of a licence. The competent authority may order the
> invalidation of certificates when facts warrant the assumption
> that certificates have been forged or are not adequately
> protected against forgery or when technical components
> used for the signature keys reveal security flaws enabling
> digital signatures to be forged or signed data to be
> manipulated without detection."
>
> §8(3): "The competent authority shall invalidate
> certificates which it has
> issued according to §4(5) when a certification authority
> ceases operation or its licence is withdrawn
> or revoked."
>
>
> Assume a CA looses its license, for example because it has
> lost its money.
> According to §8(3) the competent authority (= the german root CA)
> must revoke the certificate.
>
> By §13(5) user certificates must remain valid if a CA looses
> the license.
>
> So we have a revoked CA certificate and valid user certificates.
> This case can not be handled by the standard X.509 model.
>
> ---
>
> The SigG model is an easy and effective model.
> Assume a two level hierarchy:
> root CA
> CA
> users
>
> 1. Now Alice wants to verify 10000 digital signatures
> with respect to the standard model.
> She decides that she needs online verification of certificates.
> For the first signature she must ask her online service
> three times:
> to verify the user certificate
> to verify the CA certificate
> to verify the root certificate
> So for 10000 verifications she needs 30000 requests.
>
> 2. On the other side, Bob verifies the same amount of signatures
> by the SigG model.
> He first verifies the CA and the root CA certificates.
> He can store the results and reuse them in the future.
> So for 10000 verifications Bob needs 10002 requests.
>
> ---
>
> A standard X.509 directory service may be joined with the
> german signature law.
> Alice ask this service for the certificate of Bob.
> The service answers by sending Bob's certificate
> (if Bob has allowed this).
> The certificate is signed by the CA, like always,
> but it has no extra signature.
> The meaning of the answer is:
> Alice, this is Bob's certificate. It may be valid
> or not. If you want to know the exact status,
> ask the validation service.
>
> If we replace the words "validation service" by "OCSP"
> then this is exact the meaning we have in the standard model.
>
> Greetings,
> Michael
>
> ---
>
> Michael Herfert
> GMD - German National Research Center for Information Technology
> Darmstadt
> Germany
>