Subject: RE: Employee Certificates - Security Issues

From: "Aisenberg, Michael" <[email-masked]>
Date: Mon, 7 Oct 2002 12:51:37 -0400

Don't know if anyone is aware that the EU is presently reviewing a new
draft
Directive on invoicing.....

Michael Aisenberg
--VeriSign/D.C.--

-----Original Message-----
From: Anders Rundgren [mailto:[email-masked]] 
Sent: Monday, October 07, 2002 11:17 AM
To: Housley, Russ
Cc: [email-masked]
Subject: Re: Employee Certificates - Security Issues

Russ,

What I'm basically saying is that authority should be a part
of message "payload" otherwise we don't gain much by
going from paper to electronics.  For the very first contact between two
prospective business parties, you need some out-of-band communication,
but that should be it.

Using the Internet-bank model you have all the means to do this,
_today_, and using arbitrary authorization "granularity" as well.

The Internet-bank model eliminates out-of-band authority- management,
reduces privacy problems, and enables automatic non-intrusive archiving
and control.

As this model leads a 1000-1 deployment-wise compared to
inter-enterprise-PKI, it ought at least be taken in consideration, by
particularly the public sector, before they are trapped into
monstrosities like bridge CAs etc. creating systems supporting _none_ of
the qualities described above.

Actually I would be extremely happy if someone else wrote
how a simple thing like a purchase order should be handled
in a classical enterprise-PKI, including possible business systems.
Without such a description this entire thread becomes both
unintelligible and pretty boring.

=========================================
Russ, would you care to take on this completely death-
defying challenge?
=========================================

Regards
Anders

----- Original Message ----- 
From: "Housley, Russ" <[email-masked]>
To: "Anders Rundgren" <[email-masked]>
Cc: <[email-masked]>
Sent: Monday, October 07, 2002 15:37
Subject: Re: Employee Certificates - Security Issues

Anders:

In the paper world, any employee of a company can sign a letter on the 
company's stationary.  The use of the company letterhead may give the 
message recipient a warm fuzzy feeling, but it doe not immediately mean 
that the signer has the authority to commit the company's resources.
This 
can be confirmed.

Similarly, the use of a digital signature issued by a company provides a

similar warm fuzzy feeling.  However, the need to confirm the authority
to 
commit company resources is still needed.

Russ

At 07:25 AM 10/4/2002 +0200, Anders Rundgren wrote:

>"I, the Company"
>
>When employees have been equipped with digital certificates, linked to 
>the organization, interesting things happen: Employees can now sign on 
>behalf of the organization.  Due to the absence of a generally 
>understood X509 "authority" system, you can probably sign whatever you 
>want and an external receiver is meant to believe that you have the 
>right to do it.  This is probably as far from an organization-adapted 
>solution one can get (as organizations want to have control over their 
>internal and external actions), and is an indication that this scheme 
>is not suitable for large-scale deployment.
>
>As a countermeasure one could think of having an
>"authority control server" checking and logging all employee actions. 
>Unfortunately that does not work; if you have an employee certificate 
>you can fairly easy create messages that to receivers, look perfectly 
>valid without going trough the authority server.
>
>Summary: An architecture that is fundamentally broken.
>And, yes, I forgot to mention costs, privacy, archiving, and the 
>multitude of roots that you have to cope with.
>
>Comments?
>
>Anders Rundgren

---

From: "Anders Rundgren" <[email-masked]>
Date: Mon, 7 Oct 2002 20:33:37 +0200

Michael,

>draft Directive on invoicing.....

I sure am.   The EU have very interesting ideas about security.
Their preference is that you use Advanced Electronic Signatures which
are PKI-based such tied to an _individual_.  When I asked if telecom-
operators are supposed to hire hundreds of employees for signing
"e-invoices" using PIN-codes etc. in order to create valid invoices,
I got the answer that you can use "EDI" (!) instead to avoid the
signature requirement.  I wonder how secure XML is supposed to
be :-)

Cross-border invoicing is probably years away as each country
may do their own security variant.

Anders

----- Original Message ----- 
From: "Aisenberg, Michael" <[email-masked]>
To: <[email-masked]>; <[email-masked]>
Cc: <[email-masked]>
Sent: Monday, October 07, 2002 18:51
Subject: RE: Employee Certificates - Security Issues

Michael Aisenberg
--VeriSign/D.C.--

-----Original Message-----
From: Anders Rundgren [mailto:[email-masked]] 
Sent: Monday, October 07, 2002 11:17 AM
To: Housley, Russ
Cc: [email-masked]
Subject: Re: Employee Certificates - Security Issues

Russ,

Regards
Anders

----- Original Message ----- 
From: "Housley, Russ" <[email-masked]>
To: "Anders Rundgren" <[email-masked]>
Cc: <[email-masked]>
Sent: Monday, October 07, 2002 15:37
Subject: Re: Employee Certificates - Security Issues

Anders:

Russ

---

From: David Maurus <[email-masked]>
Date: Tue, 08 Oct 2002 19:50:57 +0200

[forgot to copy the list, so here again:]
Anders,

Anders Rundgren wrote:

> in a classical enterprise-PKI, including possible business
> systems.  Without such a description this entire thread
> becomes both unintelligible and pretty boring.
>
As most people on this list probably have a vision of how a purchase 
order in the context of a classical enterprise-PKI would work, I think 
it would also help to increase the value of this thread if you would 
describe what you mean exactly by the term "Internet-bank model", 
especially in the context of PKI and signatures.

How would a purchase order work in your non-classical 
"Internet-bank-model"-PKI?

- David

---

From: "Anders Rundgren" <[email-masked]>
Date: Tue, 8 Oct 2002 22:00:43 +0200

David,

Nema Problema, here it is:

Using the time-proven Internet-bank model, clients (= employees)
get keys (some kind of...) to their accounts, but never ever the
"bank-keys", as the latter are exclusively used for _authorized_
inter-bank  (= inter-organization) communication.  I.e.
the latter "execute" on a secure server only.

The "bank model", which was from the earliest days (1700?)
heavily founded on accountability and security, has a long-
term _sustainability_ due to its "trust-center" foundation.

The bank-model allows arbitrary complex authorization
messages as they are created on a server that can in a
single message pack signed authority documents from
various external authorities.  This removes the need
for updating authorization data out-of-band as the
"payload" contains everything you need.  Or could at least.

As purchase orders do not require personal signatures
to be honored, a procurement system simply "stamps"
outgoing purchase orders using the organization key.
It also means that it is impossible to create a valid
purchase order except going through the procurement
system giving non-intrusive (invisible, as long as
you stick to the rules) archiving, user control, 
privacy protection and a simple stable digital identity 
to trading partners.  The latter is extremely important
particularly given the pretty crude products currently
offered by commercial CAs.

A legally binding court verdict is likely to require a bit
more.  A dual-signed message seems like a possibility.
Judge + Court where the court's authoritative
signature is at the outermost layer to be valid.  Well, there
could be an additional TSA signature as well.

I just talked to a very experienced person from the
Swedish health-sector who claimed that this model is
_exactly_ what they are thinking of.  Regarding privacy
he had noticed that even badges nowadays have been
privacy-enhanced by having no SSNs and just
"John D, M.D." as clients could harass staff.

A document is in preparation based on the feedback
gathered in many discussions including those on
this list.  Stay tuned!

cheers,
Anders

----- Original Message ----- 
From: "David Maurus" <[email-masked]>
To: <[email-masked]>
Sent: Tuesday, October 08, 2002 19:50
Subject: Re: Employee Certificates - Security Issues

- David

---

From: J Adrian Pickering <[email-masked]>
Date: Tue, 08 Oct 2002 23:29:09 +0100

This discussion seems to be circling around the issue of roles. I thought 
that Attribute Certificates were invented to solve this? Someone did 
mention this but I'm not sure there was an answer.

I can have an individual certificate 'J Adrian Pickering' that I obtain, 
perhaps issued by a government authority much like a passport. When I work 
for Company X in role Y, the Company issues me with an appropriate 
attribute certificate. The two, when used together, are applied to Company 
transactions and are understood by the recipient to mean 'this individual 
has signed this transaction on behalf of company x in their role as y'. 
This is just like a traditional legal document where an individual signs 
and it is endorsed by the company seal.

When I leave the company or the company leaves me, then I retain my 
personal certificate but the 'keys of the office' (aka seal) are taken away 
from me i.e. the attribute certificate. I am still free to sign 'cheques' 
with my personal certificate whether I'm in the employ of the company or 
not. I am also free to be employed at other companies who will also issue 
appropriate ACs.

The recipient is always left to work out whether that means the transaction 
is valid or not i.e. if the signatory is authorised to make a binding 
contract. PKI provides the tools to help make this assessment.

Are we still working with unrelated certificates or do we still believe in 
ACs? Apologies in advance if I'm beating an old drum,

Adrian Pickering/
ECS, University of Southampton, UK