[15050] in cryptography@c2.net mail archive
RE: Non-repudiation (was RE: The PAIN mnemonic)
daemon@ATHENA.MIT.EDU (Amir Herzberg)
Sun Dec 28 12:05:47 2003
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Thu, 25 Dec 2003 12:46:39 +0200
To: "Carl Ellison" <cme@acm.org>, <cryptography@metzdowd.com>
From: Amir Herzberg <amir@herzberg.name>
At 04:20 25/12/2003, Carl Ellison wrote:
...
> If you want to use cryptography for e-commerce, then IMHO you need a
>contract signed on paper, enforced by normal contract law, in which one
>party lists the hash of his public key (or the whole public key) and says
>that s/he accepts liability for any digitally signed statement that can be
>verified with that public key.
Of course! I fully agree; in fact the first phase in the `trusted delivery
layer` protocols I'm working on is exactly that - ensuring that the parties
(using some external method) agreed on the keys and the resulting
liability. But when I define the specifications, I use `non-repudiation`
terms for some of the requirements. For example, the intuitive phrasing of
the Non-Repudiation of Origin (NRO) requirement is: if any party outputs an
evidence evid s.t. valid(agreement, evid, sender, dest, message,
time-interval, NRO), then either the sender is corrupted or sender
originated message to the destination dest during the indicated
time-interval. Notice of course that sender here is an entity in the
protocol, not the human being `behind` it. Also notice this is only
intuitive description, not the formal specifications.
> > Best regards,
> >
> > Amir Herzberg
> > Computer Science Department, Bar Ilan University
> > Lectures: http://www.cs.biu.ac.il/~herzbea/book.html
> > Homepage: http://amir.herzberg.name
> >
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