Re: Non-Mathmatical Forging of PKI Digital Certificates / Throwing Rocks at the PKI

[Christoph Puppe <christoph.puppe () DEFCOM-SEC COM>]

On 18 Aug 2000, Timothy J. Miller wrote:

> ...
> So in actual practice, you need to go further than just offering
> validity checking.  There needs to be some mechanism whereby the
> source of authority can guarantee that for some arbitrary PKI
> transaction, the parties engaged actually performed a validity check.

  You could only do this, when the parties involved have to use the
CA. An example could be timestamping, as required by some contracts where
a third and trusted party does a signature to vow for the time the
transaction took place. This could be bound to a validity checking that
is only given if the parties have checked each other before this.


> ...
> We don't have this for PKI transactions.  Now I know a little about
> OCSP (Online Certificate Status Protocol), but does OCSP provide a
> mechanism to force a participant to validate the certificate, and
> invalidates the transaction if not completed?

  You could tell (programm) any client to lookup the cert before he does
accept a signature or challenge-response, but I know of none that has this
feature.

> smartcard-enabled company, when the CEO forgets his smartcard at home
> are *you* going to tell him that he *must* drive home and get it, or
> are you simply going to snatch his private key from escrow and issue
> him a temporary card?

  He should fire you if you don't.

  Gruss

  Christoph Puppe
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