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At 10:54 PM 2/5/99 -0600, Black Unicorn wrote:
"But the agreement you signed with the brokerage waives the brokerage's
liability for transactions where your keys are used."
That's perfectly valid. It's the signer relinquishing his right to
repudiate, because of a normal contract he signed with the verifier of the
signature. What's enforced in court is the normal contract, not some
fiction about non-repudiation as a side effect of using digital signatures.
I concede that non-repudiation and its definition are issues but this is
more than a bit defeatist. The excuse that "non-repudiation is too
non-defined for us to try and accommodate any functionality that approaches
it" is just silly.
I'm quite happy with the contract approach you outlined. It's just the
silly talk we occasionally hear about digital signatures giving
non-repudiation -- or some certificate from a properly blessed CA giving
non-repudiation that I contest. There are laws (e.g., Utah) that deprive
you of the right to repudiate if you get a certificate from some CA they
bless -- which is enough reason, in my mind, never to get a certificate from
such a CA. It was, after all, the Reg E right to repudiate credit card bill
line items that made electronic commerce thrive.
I could apply this approach to encryption. "Why bother to encrypt? I have
no idea who's at the other end. Anyone could be a man in the middle for my
friend. They could sniff it with a Trojan horse on his computer. They
could put a video camera in his ceiling and watch his screen, or his
keyboard." This is effectively the approach you are taking.
In fact, I use that argument too. There is no such thing as a man in the
middle attack if I'm communicating with someone I don't know already. If I
have made contact with a stranger and some man in the middle is there, then
I'm still communicating directly and privately with a stranger: the man in
the middle. I have no reason to prefer him over the other stranger, given
that I don't already have a relationship with either of them. One might
argue that the MITM is dishonest while the other bloke is honest, but I defy
someone to create a protocol that tests for honesty.
My point is that the brokerage does not now have the tools to even provide
evidence of the signature in the first place, which- in fact- makes use of
the signature pointless as it provides not even the slightest advance in
non-repudiation. Might as well just keep taking passwords or use
handwriting analysis.
Don't run down handwriting too much. The handwritten signature is, after
all, a biometric.
If you want this software to be utilized in places where it counts, which is
of course why we are in this game, or should be, then you have to improve
the product/protocol, not try to explain why functionality that is
needed/useful doesn't exist.
Of course.
Mr. Geiger points out that this functionality, or lack thereof, is not a
consequence of the OpenPGP data structure itself. Insofar as that is so
this discussion is probably out of place anyhow.
Probably.
- Carl
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+------------------------------------------------------------------+
|Carl M. Ellison cme(_at_)acm(_dot_)org http://www.pobox.com/~cme |
| PGP: 08FF BA05 599B 49D2 23C6 6FFD 36BA D342 |
+--Officer, officer, arrest that man. He's whistling a dirty song.-+