GW vs E2E Security. Was: Call for input: Asia PKIF Forum Panel Discussion

>I have to say that I think you construct a 
caricature of security, then 
>shoot it down, and then extrapolate to 
reach some fairly extreme 

>conclusions!  

Stephen,

This must be a compilation on many other 
messages because the question to the Asian PKI 
forum was not that exciting :-)

 

Anyway, your response contains a theme worth 
commenting on as it is really a thing 
that to date has been poorly analyzed in 
general.

 

Secure e-mail, a caricature of 
security

If I would ever use the phrase caricature of 
security, I would refer to the security 
architecture for Internet mail.   The deficiency of this model have costed, and is still costing businesses over the 
world, many billions of dollars lost yearly, due to spam, viruses and 
phishing.

Most of the problems above, would have been thwarted 
in their infancy if the architects behind secure e-mail had realized the 
difference between a limited set of mutually trusted government agencies and the 
billion+ users now on the Internet. 

 

As hardly nobody on the entire planet could 
have guessed this development, I think it would be highly incorrect 
to blame the authors of S/MIME for this situation.  However, it is 
equally incorrect not to acknowledge this situation and ways of 
dealing with it. 

 

Solving e-mail security step by 
step

It might be of interest to know that "Internet-scale" companies Yahoo and 
Cisco have teamed-up to create a new e-mail security model not based 
on E2E security.   It will certainly not cure all problems we 
have today (too late), but it is based on a domain signature scheme that will 
allow stepwise improvements instead of the "flag-day" syndrome imposed by the 
end-to-end approach.

 

GW/E2E security in enterprise transactions
>I agree 
with you Anders that a great many enterprise transactions are best 

>secured at the gateway (especially from an encryption point of 
view).  
>This is a good model indeed, but not the only one, and not 
a "competitor" 
>to end-to-end security. 

Regarding "competition", 
may I repeat my request (that I have also forwarded to the organizers of PKI 
Workshop 2006)?  I have to date not seen a single description of 
an existing end-to-end secured multi-user purchasing system, which I claim 
is because there probably is no such system.  If I'm wrong I would 
like to get some evidence of this including reasonably clear descriptions on how 
messages are secured between the large number of parties that are 
involved in such processes.  Since the purchasing process actually can be 
mapped to many other multi-party processes, I feel this is a generic 
issue.

 

BTW, there are IMHO at least as many reasons for using GW signatures as 
there are for using GW encryption.  In the B2B world I believe the 
requirement that an E2E secured message must be in the 
true destination format also in the sender's client is the biggest 
hurdle, as it excludes current, mostly web-based systems.  There simply is 
not enough money available for funding the development of thousands and 
thousands of unique "fat clients", particularly as "the other solution" is 
readily available as well as being inherently more 
flexible.  Client-side authentication using SSL fills the 
security bill in a much less intrusive way.  However, that security does 
not have to reach beyond the business system as the business system is an 
entity itself in a GW-world.

>I know from a New Zealand project 
several years ago that they implemented 
>government-wide gateway PKI only 
because they couldn't get smartcards and 
>client software as they existed 
back then to work.  They viewed gateway 
>PKI as effective BUT a 
compromise, because they lost strong authentication 
>of 
individuals.  That is not a bad compromise in many cases; and there are 

>other ways to get individually auditable proof of origin.  But it 
is a 
>compromise nevertheless. 

That is a rather one-dimensional way of 
describing this system. Seen from another angle, I note that SEEMail 
enabled domain-encrypted and -authenticated mail communication to EVERYBODY 
within the government network with minimal costs including virtually no end-user 
training.  The US government OTOH have not reached that goal even today by 
a long shot as they are stuck with a system that does not scale trustwise 
(end-to-end security using S/MIME).  Apparently, the New Zeeland government 
is now extending this concept to include citizens and businesses as well: 
http://www.e-government.govt.nz/see/mail/index.asp

Germany's e-Government adopts the GW 
approach

I just returned from a conference in Hungary called 
ISSE 2005 (Information Security Systems Europe) where I presented an 
authentication solution on behalf on my employer.  Fortunately, I was 
also able to attend a presentation by a BSI (the NIST of Germany) delegate 
who presented their gateway approach for e-government transactions and 
messaging.  The person started with a slide containing the line: 
"End-to-end security died even before it even was alive".  I could not have 
put it better myself.  This was not a research report but a real system 
based on a set of new BSI standards, and coming from the country that more than 
any other country has been associated with legally binding signatures, qualified 
certificates and similar.

 

Based on publicly available information, the 
governments in the US and in Asia have (apparently) concluded 
that they do not need a security architecture for interacting with the society 
at large.  This is a pity, since HSPD-12/PIV does neither 
address (in the original text at least), cross-agency messaging nor G2B 
messaging, it is rather designed to secure access to federal 
resources.  The original use-case should work just fine, while the extended 
use-case often does not.  "How do you send an encrypted message to the tax 
department" (which the BSI representative mentioned as an example), is in its 
extreme simplicity showing that this is not simply a matter of using smart cards 
or not, it is rather a security architecture issue.  The BSI question 
also indicates that there are privacy issues that are not particularly 
well addressed by the E2E model (while definitely by its 
challenger).

 

The way ahead?

The extreme positions taken by different "PKI 
theologists" (unfortunately including myself), have so far created a huge 
gap benefiting nobody.  It is however, indeed possible combining 
these two diverging paths creating a very potent security architecture that 
as a bare bone minimum uses GW security for organization-to-organization 
messaging, while it underneath can tunnel an individual's signatures for 
the rather few cases where such are needed.  In fact, this super-simple 
scheme can address authorization in a way that E2E security cannot, by making 
the semantics of a GW-signature indicate "archived", "checked", and 
"authorized".  A standalone E2E signature OTOH, does not look any 
different whether it has passed directly from the desktop of the individual 
or have gone the "proper way" trough internal systems.  That is, 
E2E-signatures seem most suited for internal consumption, 
while GW-signatures mainly have external 
applicability.   Last but not least, a 
combined GW+E2E-signature would denote an authorized 
signature by an individual representative of an organization, where the 
signature is intended for external consumption.  Since the outer GW 
signature may not only embed the E2E signature, but any number of applicable 
authorization attributes, this scheme offers an "in-transaction" alternative to 
the virtually non-existent X.509 attribute certificates.

 

Once again, I would 
like to emphasize that a security architecture and smart cards are not 
equivalent, smart cards are rather a potentially vital piece of such an 
architecture.  By adopting a migrative approach to security, I believe 
smart cards will be much more quickly adopted (=used) than approaches 
requiring that not only your organization switch to full-blown PKI deployment, 
but also requiring every organization you want to interact with does this as 
well and at the same time, using the same policies etc.  That's at least 
what most governments and banks are thinking in the EU.

 

Anders Rundgren

Located in the EU, working for a major US computer security 
company, but here only representing myself.