Subject: Employee Certificates - Security Issues

From: "Anders Rundgren" <[email-masked]>
Date: Fri, 4 Oct 2002 07:25:08 +0200

"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: Juergen Brauckmann <[email-masked]>
Date: Fri, 04 Oct 2002 08:25:42 +0200

Anders Rundgren wrote:
> linked to the organization, 

"When employees have been equipped with paper with the official letter
head of the organization..." 

> interesting things happen: Employees
> can now sign on behalf of the organization.  
[...]
> Summary: An architecture that is fundamentally broken.

Only if you see PKIs as something completely separate to how business is
done in the non-PKI-world. If you regard PKIs as an additional means of
supporting business, you will not have the fundamental problems you
describe. People can write letters that look like authorized papers from
their company today, and this is definitely not a big problem. Of course
you need some measures against unauthorized actions by employees, but
these don't have to be enforced by technical solutions.

Regards,
   Juergen

---

From: "Anders Rundgren" <[email-masked]>
Date: Fri, 4 Oct 2002 08:38:26 +0200

Juergen,

Obviously you believe that it is of fundamental value to transfer all
the weaknesses of the "paper-world" into the "e-world".

I find this odd since the characteristics of the "e-world" are completely
different, e.g. you don't see or hear your partners.  And there are no
"carbon-copies" either.

Anders

----- Original Message ----- 
From: "Juergen Brauckmann" <[email-masked]>
To: "Anders Rundgren" <[email-masked]>
Cc: <[email-masked]>
Sent: Friday, October 04, 2002 08:25
Subject: Re: Employee Certificates - Security Issues

[...]

Regards,
   Juergen

---

From: Juergen Brauckmann <[email-masked]>
Date: Fri, 04 Oct 2002 09:09:43 +0200

Anders,

> the weaknesses of the "paper-world" into the "e-world".

Obvious answer: No, I don't believe that. But I also don't believe in
constructing solutions that have no corresponding problem.
 
> Summary: An architecture that is fundamentally broken.

This is simply not true, as the current situation in the e-world is not
worse than in the paper world. And paper world works.

Of course there is room for improvements, e.g. means of authorizing
transaction, but "fundamentally broken" is not the reality.

Regards,
   Juergen

---

From: "Anders Rundgren" <[email-masked]>
Date: Fri, 4 Oct 2002 09:49:40 +0200

Juergen,

>constructing solutions that have no corresponding problem.

You don't have to.  The Internet-banks, used by 42 million people 
only in Europe, already have.  They let clients [employees]
authenticate to bank-servers [company business systems] and
transactions are created by the server only.  After doing various
checks of the user, and performing archiving [carbon-copy].
The keys needed for transferring money from one bank to another 
[company keys], are _never_, _ever_ distributed to clients.

Are organization-based transactions, decisions, purchase orders,
etc. really very different to banking?  In my opinion they are not.

Anders

---

From: "Marc Poulaud" <[email-masked]>
Date: Fri, 4 Oct 2002 09:07:41 +0100

Umm. I always think back to the good old days of the real world and how
things get done on paper.

Simply put, a digital signature replaces the wet equivalent. It in no way
infers authority to any action i.e. it only says something about the
identity of the employee (in this example). Authority is something else.

I think it is also useful to consider the act of signing separately to the
act of due diligence on the part of the relying party. This will differ
based on the context in which the business is taking place, and consequently
the solution used to check this authority/entitlement/permission etc.

Importantly also, is the need to consider this as a set of layers. Solve the
identity piece at one, authorisation at the next. The business problem being
addressed will affect both (and all) layers. Therefore, I think your example
solution to this problem and this particular level may work in some business
scenarios (but not all :).

Also, the consideration of identity and authority of the Authoriser needs to
be considered. You wouldn't want to rely on my say-so, for example.

x.509 or the architecture ain't broken. Understand the business problem,
then address the right technical solution.

Marc.
-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Anders Rundgren
Sent: 04 October 2002 06:25
To: [email-masked]
Subject: Employee Certificates - Security Issues

"I, the Company"

Comments?

Anders Rundgren

---

From: Juergen Brauckmann <[email-masked]>
Date: Fri, 04 Oct 2002 10:42:27 +0200

Anders Rundgren wrote:
> The Internet-banks, used by 42 million people

I don't see the relevance of your example to your inital statement that
employee certificates are "fundamentally broken" [I hope that I did not
misunderstand you here].

Of course it is possible to create architectures that enhance the
reliability und trustworthiness of electronic transactions. And of
course there are scenarios where these architectures are needed. And
almost certainly these architectures will use (employee) certificates. 

But a) there are enough cases where you don't have to spend much money
on highly secure solutions because simpler solutions with other trust
models work as well, and b) what is the relation to certificates and
public key infrastructures?

Regards,
   Juergen

---

From: "Anders Rundgren" <[email-masked]>
Date: Fri, 4 Oct 2002 11:15:14 +0200

Juergen,

><snip>
><snip>

>I don't see the relevance of your example to your initial statement that

[company keys] is the key to the answer :-)
Employee certificate => company key => no control => "fundamentally broken" 

>reliability and trustworthiness of electronic transactions. And of
>course there are scenarios where these architectures are needed. 

Why bother with PKI if you don't need reliability and trustworthiness?
Particularly if the context is external communication.

>And almost certainly these architectures will use (employee)
>certificates. 

No, the Internet-bank model does not require any "particular" client-
certificates, it is enough that you are recognized/accepted/trusted as
no traces of client certs ever leaves your bank.  You can use a "civil"
ID-card with no information about bank, employment etc.
A major Swedish bank is buying such from a TPP to take a example.
So could other organizations do as well.

>models work as well,

The Internet-bank model is a lot cheaper than deploying PKI over
an entire organization.  That's why it has been a great success
compared to employee-PKI.

> and b) what is the relation to certificates and public key infrastructures?

If we talk client-PKI it ranges from 0 to 100%.  Only the server is
100% PKI.  Organization (only)-PKI.  Web-Server PKI.

Anders

---

From: "Anders Rundgren" <[email-masked]>
Date: Fri, 4 Oct 2002 14:58:15 +0200

Marc,

>Understand the business problem, then address the right technical solution.

I believe I just did :-)

Archiving and control of employees' activities is an integral part of _every_
business process worth mentioning.  By deploying solutions that do not
support these basics, PKI does only add costs but no real security or
trust for the employee organization.  And organizations, in the same way
as individuals, tend to care most about themselves.

>x.509 or the architecture ain't broken.

X509 is certainly not broken, it is the concept of employee-based PKIs
that is broken.  It is a merely direct copy from the paper-world, which
has proven to work pretty bad in many other cases.  Like it has for
credit-card numbers on the Internet.

cheers,
Anders

---

From: "Housley, Russ" <[email-masked]>
Date: Mon, 07 Oct 2002 09:37:05 -0400

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

---

From: "Anders Rundgren" <[email-masked]>
Date: Mon, 7 Oct 2002 17:16:56 +0200

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:

Russ