Subject: Re: Possible solution?, was Re: Non-Repudiation

From: [email-masked]
Date: Wed, 11 Aug 1999 22:04:31 -0400

(snip)
Tony Bartoletti wrote:

>4   Take a certificate with the nonRepudiation bit off --
>is this a negation, or a declaration of non-existence, or a
>declaration of an ignored feature?  To clarify, if the NR
>bit is off, does it mean that the NR is denied, or that
>NR does not exist, or that NR can still be provided if so
>declared elsewhere?
>
>[Tom Gindin]   It might mean "proceed at your own risk", as well.  That would
>deny NR, but not necessarily the transaction.

Once again (now in reverse) if you intentionally sign a contract,
in the presence of suitable witnesses (for example), using a
key whose cert has the NR bit OFF, with the hope of being able
to later repudiate the signature, I may still be able to take you
to court and "prove" non-repudiability, if I have collected some
other suitable evidences that you were in sole possession of the
key, and expressed intent, etc., regarding the act.

So NR is NOT denied.  At most, the cert says "the CA denies".

[Tom Gindin]   In the case of a remote automated access, the absence of an NR
bit would make a difference.  Of course, an individual can always make a
contract, and with enough witnesses an "X" is sufficient.  The NR bit might
enable denial of an agent relationship all by itself, however.  Personally, I
would imagine that for the next generation or so formal contract signings with
witnesses will involve the signing of a written summary of the contract with a
reference to a digital object signed by each party.  Such a procedure would
certainly have greater assurance than the conventional one, because of the
non-severability of digital signatures, and repudiating the digital signature
will not overturn the contract signature anyway.

As a general rule, assuming we trust a CA to any degree, it would be
well to remember that a certificate can never say anything more than
"the CA says X", since it is nothing more than a document signed
with their issuing key.

Regards,

___tony___