Non-repudiation (was RE: The PAIN mnemonic)

[Ben Laurie]

Ian Grigg wrote:
> Carl and Ben have rubbished "non-repudiation"
> without defining what they mean, making it
> rather difficult to respond.

I define it quite carefully in my paper, which I pointed to.

> Now, presumably, they mean the first, in
> that it is a rather hard problem to take the
> cryptographic property of public keys and
> then bootstrap that into some form of property
> that reliably stands in court.
> 
> But, whilst challenging, it is possible to
> achieve legal non-repudiability, depending
> on your careful use of assumptions.  Whether
> that is a sensible thing or a nice depends
> on the circumstances ... (e.g., the game that
> banks play with pin codes).

Actually, its very easy to achieve legal non-repudiability. You pass a 
law saying that whatever-it-is is non-repudiable. I also cite an example 
of this in my paper (electronic VAT returns are non-repudiable, IIRC).

> So, as a point of clarification, are we saying
> that "non-repudiability" is ONLY the first of
> the above meanings?  And if so, what do we call
> the second?  Or, what is the definition here?
> 
> From where I sit, it is better to term these
> as "legal non-repudiability" or "cryptographic
> non-repudiability" so as to reduce confusion.

Read my paper (it was co-authored with a lawyer, so I believe we've got 
both the crypto and legal versions covered).

Cheers,

Ben.

-- 
http://www.apache-ssl.org/ben.html       http://www.thebunker.net/

"There is no limit to what a man can do or how far he can go if he
doesn't mind who gets the credit." - Robert Woodruff

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