Subject: DS, NR and their legal effects

From: Ed Gerck <[email-masked]>
Date: Mon, 13 Dec 1999 07:22:21 -0800

All:

From  time to time, discussions in this WG have revolved 
around the issue of legal effects and intent of authentication
(as indicated by setting the DS bit) and non-repudiation (as 
indicated by setting the NR bit). Even though these discussions
exceed the technical charter of this WG, I understand that some
posters might feel that "something is missing" unless we 
introduce words about the legal or binding effects of the DS bit
and, especially, of the NR bit. This message intends to help 
clarify the issue and show that what is "missing" belongs indeed
to another layer -- the legal layer.  And, there should it rest 
if we want to improve interoperation lest we want PKIX to be tied
in to one particular legal system and time, and fail in others.

Technically, it has become clearer in these discussions that 
authentication and non-repudiation are distinct services (as 
clearly stated also in X.509v3) and that *both* the DS and NR 
bits are necessary to indicate what I might call the "signature 
state".

Many agree that we cannot "deprecate" either because we would be 
missing an essential state variable and we could not adequately 
describe some digital signature systems. Suffice as limitation 
that the DS bit applies only to asymmetric signature algorithms.

However, about the evidenciary consequences of authentication and
non-repudiation?  They would directly impact the ability of digital
signatures to be used in e-commerce and to be enforceable in a court
of law. Do we need to include words to this effect in PKIX, in order
to allow PKIX to be applied as a commercial tool?  Do we need to
include the legal layer in PKIX? My opinion has been that we should not 
-- even though we need to keep an eye on the legal layer in order to
verify if we are providing an adequate firm basis for it, whatever it
might reasonably be. 

In this aspect, I present the current interpretation provision
from the latest version of the UK Electronic Communications Bill 
(thanks to Nicholas Bohm for sending it to me):

"In this Act- 
                                 
(a) references to the authenticity of any communication or data are
references to any one or more of the
following- 
     
(i) whether the communication or data comes from a particular person or
other source;

(ii) whether it is accurately timed and dated;
     
(iii) whether it is intended to have legal effect"

The Act provides that an electronic signature is admissible as 
evidence of the authenticity of a message or data, and paragraph 
(iii) above was inserted to meet the reproach that the original 
version failed to acknowledge that a signature is more than 
evidence of authenticity, it is evidence of an intention to 
adopt and approve what is signed.

IMO, this provision thus does shed light into what the legal layer 
might include -- which largely solves the issue whether 
"something is missing" in PKIX. Indeed, "something is missing"
but on purpose, because it is out of scope and provided elsewhere.

Cheers,

Ed Gerck