Subject: Re: A $25,000,000,000 PKI Was:Spec. on QC-low-fat & QC-heavy-bio

From: Stefan Santesson <[email-masked]>
Date: Thu, 08 Apr 1999 16:52:27 +0200

Anders,

First of all - I'm not a lawyer. All I'm saying is just my opinion.

Second. The person responsible for a signature, regardless of type, is the
person who created it and whose intent it expresses.

I.e. You are ALWAYS responsible for signatures created by YOU and you are
NEVER responsible for signatures created by someone else.

Who owns the techiqe, keys, system, infrastructure etc. are totally
irrelevant to this fact.

So, last, what remains is the problem of providing strong evidence if the
above fact is repudiated. I.e. if you deny that a signature was created as
e result of your consious act, representing your intent.

This however WILL be dependent on technique, keys, system, infrastructure etc.

So when we are talking about law and technique, we are ONLY talking about
factors which effect the EVIDENCE VALUE. Not factors that decide whether a
signature is legal or not.

ALL SIGNATURES ARE LEGAL. It's only the fact that some of them are harder
to prove in court than others.

/Stefan

P.s. Th above should not be mixed with the fact that some authorities may
require a minimum security level for signatures in order to accept them
(e.g. for a signature to be in hand writing). This is an option open to all
relying parties, i.e. to say - It has to be at least this good or I will
reject it.

At 07:14 AM 4/8/99 +0100, Anders Rundgren wrote:
>Hi Stefan + Steve,
>
>May I ask a question regarding signature laws which I am pretty ignorant of?
>
>If a company runs a SET Wallet Server for their employees to use, is not
the company
>responsible for signatures produced by the certificate and keys stored on
that server?
>
>Legally as well as technically. 
>
>Now to the users (with their CyberPhones) that initiates transactions:
They are responsible to
>their company that as a minimum records all transations with user
identity.  Or
>it could require a sign op as well.
>
>Looks OK to me.
>
>So what is so fundamentally flawed in the CyberPhone concept with respect
to digital
>signature laws?
>
>Regards
>Anders
>http://www.mobilephones-tng.com
>
>
-------------------------------------------------------------------
Stefan Santesson                <[email-masked]>
Accurata Systemsäkerhet AB      http://www.accurata.se
Slagthuset                      Tel. +46-40 108588              
211 20  Malmö                   Fax. +46-40 150790              
Sweden                        Mobile +46-70 5247799

PGP fingerprint: 89BC 6C79 5B3D 591B 8547  1512 7D11 DBF4 528F 29A0
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---

From: Patrik Fältström <[email-masked]>
Date: Thu, 8 Apr 1999 19:06:47 +0200

>Who owns the techiqe, keys, system, infrastructure etc. are totally

In this step, yes. BUT, the party which you, as the signer, is 
sending the signed data to, have to trust the data itself, and the 
proposed fact that you were the one sending it.

I.e. you as a signer is signing data just because you want someone 
else to trust your information.

The infrastructure, keys, system etc is something which can be used 
at a later stage (see below).

>to prove in court than others.

In legal systems like the one we have in Sweden, any party can to the 
court use any kind of evidence. In Swedish we call it "fri 
bevisprövning". I have been told, that in other legal systems, other 
rules can exist.

It is also the case that if you also have a contract between the 
parties exchanging information, or for example the party which hands 
out the keys, things get extremely complicated -- and I have not seen 
a single person being able to come with a formula for "TRUST" ever, 
and I doubt anyone will.

    paf

---

From: Ed Gerck <[email-masked]>
Date: Thu, 08 Apr 1999 11:31:53 -0700

> a single person being able to come with a formula for "TRUST" ever,

See:

1. Ed Gerck, "Towards Real-World Models of Trust: Reliance on Received
Information", in http://www.mcg.org.br/trustdef.htm

2.  Ed Gerck, "Trust Points" from http://www.mcg.org.br/trustdef.txt excerpted in
"Digital Certificates: Applied Internet Security" by J. Feghhi, J. Feghhi and P.
Williams, Addison-Wesley , ISBN 0-20-130980-7, p. 194-195, 1998.

3. John Gregory, "Electronic Legal Records: Pretty Good Authentication?", in
http://www.callacbd.ca/summit/auth-johngregory.html

4. Lea Viljanen, with Web page at  http://www.nixu.fi/~lea/  in a paper delivered
in an Internet seminar in Finland, had the following excerpt which may well
illustrate the usefulness of the approach in [1] above:

"If we analyze the first case following Gerck's definition of trust
being "[that which is] essential to a communication channel but which cannot
be transferred from the source to a destination using that channel"
(see 2.2 ), we must first analyze what is the communication channel in
this case. Here we find that the certificates themselves are the
channel/medium with which the data conveying some trust expressions are
transmitted. So trust to the certificates themselves cannot be
transferred using the certificates.

To define trust in a communication system from this point of view also
yields the interesting point that we can have several trust requirements
for a communication system. Each observer can have a list of trust
requirements for every level of the communication system, for example
trust for the hardware, trust only data carried by operator X or only
within our own corporate network, trust only data-origin-authenticated
messages etc. For us to trust the information received from the
communication all these trust conditions must be satisfied. The
existence of these multiple layers of trust is usually ignored."

Cheers,

Ed Gerck