Subject: Digital Signature Implementation Interoperability

From: "Mike Henry" <[email-masked]>
Date: Wed, 27 Oct 2004 11:04:53 -0400

All.

I  recently attended a session of a working group whose charter
is to "develop a strategy to address interoperability and implementation
challenges with digital signatures" across a large government enterprise

One of the explicitly stated premises of this group is that "among all the
COTS digital signature implementations there are no two that interoperate
out of the box". Interoperate here is to be understood as - a user of
product
A generates a digital signature over some data and transmits it to a
recipient
using product B who is able to verify the signature.(A and B not the same
product.)
This premise is frequently briefed to senior decision makers as an absolute
"there are none".
It is not briefed as, for example, "there are problems in interoperability
one has to
choose carefully" or some other more nuanced estimate of the situation.

This premise is an important one to this working group. If it were
demonstrably
not so in one or two  instances it would probably just require more
precision
in choice of words. If it were not so in a sufficient number of instances
(i.e
product A interoperates with B, C, D and another set E, F, G all
interoperate
quite nicely among themselves ......) then it would likely have a
significant
impact on planning and future decisions.

I was troubled by the fact that there was no evidence offered in support of
this defining premise other than  reference to undocumented phone survey
results to some sample of digital signature product vendors. It may very
well
be the case that as of Oct 2004 the implementations of the standards have
not
resulted in any interoperability, but I was not convinced by the evidence
presented.

I would very much appreciate hearing from anyone who has some independent
testing results or practical experience on this topic. If this is not an
appropriate
topic for this list then an e-mail response would be fine.

Mike Henry

Michael C. Henry
Senior Systems Engineer
MTC
In Support of USMC PK-E Initiative Office

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From: Alicia da Conceicao <[email-masked]>
Date: Wed, 27 Oct 2004 13:18:53 -0400 (EDT)

Dear Mike:

I disagree!  As someone who recently complete her own digital signature
product nearly two months ago, I cannot see why any other digital
signature products that also uses CMS signedData based signatures with
DER encoding won't interoperate with each other.
 
In other words, if I send you a DER encoded file of a CMS signedData
digital signature, then any CMS compliant software should be able to load
it up and validate it against the original document and signing certificate.
The original document and/or DER encoded signing certificate may or may
not be present in the signature, but any robust digital signature software
must also be able to load these from external binary files.

On a side note, does anyone know if there is an ISO standard yet for CMS
based digital signatures?  ISO-18014-2 was recently added for RFC-3161
based timestamps that are used in CMS, but I haven't come across any ISO
standard for generic CMS signedData.

If anyone else has any CMS signedData based digital signature software
that they would like to interop test, please let me know, since I would
be happy to test it against my own fully functional CMS software.  Prehaps
if a critical mass of CMS software providers are interested, we can even
have an interop test-fest where we all test our CMS software against each
other.

Alicia.

---

From: "Anders Rundgren" <[email-masked]>
Date: Wed, 27 Oct 2004 21:10:48 +0200

Hi Mike,

You should be aware of the fact that client signatures comes in
two flavors.  One is S/MIME (signed e-mail) which actually is
both standardized and interoperable.

However, most e-governments, banks and other advanced users of
IT have concluded that the web is the preferred method for distributing
and acquiring information including digital signatures.   In this area which
often is called "web-sign" there are no standards and no standards in
preparation either.  Most systems are currently using Java applets
to get some kind of limited cross-platform ability.

Regards
Anders Rundgren

----- Original Message ----- 
From: "Mike Henry" <[email-masked]>
To: <[email-masked]>
Sent: Wednesday, October 27, 2004 17:04
Subject: Digital Signature Implementation Interoperability

All.

Mike Henry

Michael C. Henry
Senior Systems Engineer
MTC

---

From: [email-masked] (Peter Gutmann)
Date: Thu, 28 Oct 2004 15:14:31 +1300

"Mike Henry" <[email-masked]> writes:

>appropriate topic for this list then an e-mail response would be fine.

It depends on how you define "interoperate".  If you mean "will verify a 
basic S/MIME signature with minimal (X.509v1-level) implicitly-trusted certs 
without any problems" then everything will do that pretty much out of the 
box.  OTOH if you want to do anything with any level of sophistication/
complexity then it's pretty much pot luck what'll happen.  So both points
of view are correct.

Peter.