Subject: RE: Meaning of Non-repudiation

From: Philip Hallam-Baker <[email-masked]>
Date: Fri, 6 Apr 2001 09:08:35 -0700

I am confused here. Last washington IETF myself, Russ, Denis and Tim were
taken in a black limosine off to a meeting of the joint ABA-New world order
PKI working group being chaired by Michael Baum. We had a six hour dicussion
of the non repudiation bit puctuated only by the stream of liveried servants
dishing out foie gras, oysters and caviar to the lawyers. At the end of the
meeting Tim recieved a signed and sealed statement from Michael himself
stating that we did not need to discuss the topic ever again. I hope that
Tim has not lost the statement.
 
At the meeting the strongest statement that could be agreed upon concerning
the non repudiation bit was:
 
1) The setting of the non repudiation bit in the certificate was a necessary
but not sufficient condition for a relying party to consider a signature to
have the non-repudiation property.

Beyond that there was considerable dispute as to the legal and technical
issues. I believe that the utility of the bit is limited to identifying keys
which are considered (for whatever reason) repudiable. Beyond that
non-repudiation is not a binary quality, there will always be degrees of
repudiation contol and the degree of control provided in a specific
circumstance is ultimately determined by the CP and CPS. Trying to condense
that down to a single bit is futile.
 
There is a utility in leaving the non-repudiation bit clear in a certificate
for a cable modem, 802.11b card, SSL server or the like.
 
Unfortunately the people who are most concerned about the bit tend to want
it for an affirmation that non-repudiation services be provided.
 
One solution would be to call it the 'repudiation bit' and state that when
clear repudiability was asserted.
 
        Phill
Phillip Hallam-Baker
Principal Scientist
VeriSign Inc.
[email-masked]
781 245 6996 x227

---

From: "Carlin Covey" <[email-masked]>
Date: Fri, 6 Apr 2001 09:18:53 -0700

Philip Hallam-Baker wrote
      "... We had a six hour discussion of the non-repudiation bit ....
      At the end of the meeting Tim received a signed and sealed statement
      from Michael [Baum] himself stating that we did not need to discuss
      the topic ever again.  ..."

Was the non-repudiation bit set in the certificate used to sign that
statement?

---

From: "Dr. JohnDavid Hascup" <[email-masked]>
Date: Fri, 6 Apr 2001 11:13:46 -0700

Meaning of Non-repudiationThanks Phil, I do remember there being that
discussion in DC and also much more prior on the list. I just remember that
it seemed the lawyers wanted it their way and that the bit would be
insufficent in-and-of-itself for their usage.

If my message caused a misunderstanding beyond that, mea culpa.

JohnDavid

  -----Original Message-----
  From: Philip Hallam-Baker [mailto:[email-masked]]
  Sent: Friday, April 06, 2001 9:09 AM
  To: [email-masked]
  Subject: RE: Meaning of Non-repudiation

  At the meeting the strongest statement that could be agreed upon
concerning the non repudiation bit was:

  1) The setting of the non repudiation bit in the certificate was a
necessary but not sufficient condition for a relying party to consider a
signature to have the non-repudiation property.

  There is a utility in leaving the non-repudiation bit clear in a
certificate for a cable modem, 802.11b card, SSL server or the like.

          Phill
  Phillip Hallam-Baker
  Principal Scientist
  VeriSign Inc.
  [email-masked]
  781 245 6996 x227

  Dr. JohnDavid Hascup
  Senior Security Architect
  ELF Technologies