Re: Interim signing of the root zone.

[Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>]

Edward Lewis;

> Note too that with CRL's, the incident above was easily rectified - 
> in applications that fully implemented X.509 processing.

Unfortunately for you, CRL is another example on why CA-based security
is useless.

Namely, there is no proper period to check CRL.

CAs, the intelligent intermediate systems having no knowledge on the
requirement of applications, set the period, which is inappropriate
for most applications.

> >What Masataka Ohta IMHO tries to say is that it is at best nice to
> >have a signed root zone, but you will not gain /any/ increase in security.
> 
> The goal of security is to limit the damage of an (unauthorized) 
> action. (With "damage" being inherently "bad stuff.")  Significant 
> subgoals of security are to lower the chance (probability) that an 
> unauthorized action will have any impact, limiting the impact to a 
> small set of assets, and limiting the duration of the impact.

That's why shared key cryptography, which limits the impact of
compromized security to the small set, members of which are directly
involved in the action, is the way to go.

On the other hand, the impact of compromized CAs or compromized
employees of CAs is unlimited.

> Signing the root zone means that not only will the attacker need to 
> convince resolvers that it is the true source of the root, but the 
> attacker will also need to be able to forge the signatures.  Forging 
> can be done, but that it is yet another steps to be mastered, there 
> is an even lower likelyhood of success.
> (The more times the attacker fails, the more chance the attacker has 
> at getting caught before perfecting the attack.)

It's much easier and secure to prevent forged route to the current
UNICAST root servers and to catch the attacker.

> There are no network police, but there are existing legal 
> jurisdictions.

Existing legal jurisdictions is powerful enough to discourage
forged route to the current UNICAST root servers.

> My point here is - if 
> the attacker is thrown in jail, the attack will stop by then.

Exactly.

> PS - the roots can limit damage through a key change and proper 
> dissemination of this.  This is a rougher thing to accomplish and the 
> attacker might get away with things for a while, but it is a help.

Certainly.

If the attack occurs 1,000 times a second and the roots act within an
hour, the damage can be limited below that of 3,600,000 transactions,
each of which may worth zillions of dollars.

That's why real world credit card companies requires realtime
verification of credit status.


							Masataka Ohta
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