Subject: RE: Current signature formats insufficient

From: Adrian McCullagh <[email-masked]>
Date: Thu, 13 Jul 2000 15:03:29 +1000

Simon,

I agree that there is a cost involved but the cost of not taking this
approach will in my opinion be greater to society in the long run.  There
will be an increase in identity fraud cases, an increase in the cost of
collecting admissible evidence, and the increase of other crimes such as
unauthorised access that could otherwise be reduced (as opposed to
eliminated). 

If you would like I have 2 academic papers that deal with the issues raised
here from a legal perspective.  Both papers have been published by
universities but I am not sure whether they are on the internet.

The first paper is entitled "Electronic signatures : Understand the past to
develop the future"
The second paper is entitled "Non-repudiation in the Electronic Commerce
Environment"

The first paper provides an argument that the concept of witnessing is
inappropriate for the electronic commerce environment.  A new position
legally should be the concept of verifying.  At law a witness must have an
uninterrupted view of the signer actually affixing the mark that will bind
the signer to the contents of the document.  Now a witness can not actually
see such an affixation in the digital environment.  All a witness can do is
see the person pressing some keys.  The program could be doing anything.  So
in my scenario the verifier will first verify that there does exist,
attached to the document, a digital signature that has been affixed using
the alleged signers private key.  Once verified the verifier will affix
their digital signature that will clearly note the second signer as a
verifier and not as the person who is to be bound by the contents of the
document.  My paper expands this concept somewhat.

I am completing a paper the analyses trusted systems and digital signature
regimes and establishes that most jurisdictions have ignored the trusted
mechanism that was established for some 600 years in the paper based
environment and have misdirected there attention upon the verification
process.

Adrian McCullagh
Director of Electronic Commerce
Gadens Lawyers

Tel: 617 3231 1522
Fax: 617 3229 5850

level 39
Central Plaza 1
345 Queen Street
Brisbane Australia 4000

-----Original Message-----
From: Simon McMahon [mailto:[email-masked]]
Sent: Thursday, July 13, 2000 2:41 PM
To: Adrian McCullagh; 'Tony Bartoletti'; 'Ben Laurie'; Frank Balluffi
Cc: [email-masked]; [email-masked]
Subject: Re: Current signature formats insufficient

Adrian wrote :
[snip]
> The issue that I am raising in legal terms is called "Non Est Factum" -
"not
> my act".
[snip]

A great argument for certified signing devices but they cost a lot to
create, or at least now they do because volumes aren't high enough. There
will still be demand for low cost signing devices (hackable PCs with
uncertified software and SCs).

I dont see what this has to do with signature formats however, although I
agree its an interesting and important issue.

Surely in the case you cited the Alememdios' signatures would have been
witnessed by representatives of the bank and they should have made sure the
Alemedios understood what they signed by supplying their own translator. I
guess thats why the Alemedios won.

My point is that witnessing is the right way to boost non-repudiation (that
failed in this case) to a level where big dollars are involved. Non
witnessed signatures, standard or digital, must therefore be more vulnerable
to repudiation claims. A digital witness would need to assure that the
witnessed signature was made with a trustworthy signing device and that the
signer understood what was being signed.

I can concieve of a trustworthy signing device, not at home but at a bank
branch or kiosk, that accepts a smart card with my private key on it.
Authenticates me and makes me say 'Y' to "do you understand and wish to sign
what you have read above ?" (wherever "above" happens to be) and then
applies my signature. It then counter signs my signature with its private
key which the RP can recognise as that of a trusted device. The RP may not
know for sure that I actually understood what I was supposed to have read,
only a human witness, in my opinion could do that, but the RP has high
assurance that the signature is not the result of a hacked PC with an SC
reader.

Simon McMahon

---

From: "Simon McMahon" <[email-masked]>
Date: Thu, 13 Jul 2000 16:26:48 +1000

Adrian,

> universities but I am not sure whether they are on the internet.
I'm sure they will be tough reading but, yes, please post the URLs if they
exist or post binaries direct to me (I think mailing list policy is not to
post binary attachments).

I understand that a human withness to a digital signature is at a
disadvantage for the reason you stated, but couldn't the law recognise a
certified "device" operating under its normal operating conditions as a
witness to the affixation of a digital signature to some content ? It is
after all the device doing it. A human witness could still be involved but
would be witnessing something else, e.g. that the signer understood the
content.

German law obviously already recognises certified signing devices as
relevant to legally binding signatures.

It looks to me like the concept of a witness is overloaded because humans
are naturally pretty versatile. Breaking down what a witness does, or is,
might make it easier to digitize their functions. Maybe that is what your
paper's "verifier" is.

What happened to "Current signature formats insufficient" ? Better post me
those papers quick !

Thanks,

Simon McMahon

---

From: Michael Ströder <[email-masked]>
Date: Thu, 13 Jul 2000 09:09:16 +0200

> relevant to legally binding signatures.

Maybe there's a misunderstanding here (or maybe it's because I came
into this discussion lately):

The german "Signaturgesetz" only describes how strong a
certification service has to be to be accepted for legally binding
signatures eventually being implemented in a law in the future. But
at the moment no electronic signature is accepted as a legally
binding signature at all.

Ciao, Michael.