Tom,
From: TCJones(_at_)dockmaster(_dot_)ncsc(_dot_)mil
To: pem-dev(_at_)tis(_dot_)com
Cc: ietf-edi(_at_)byu(_dot_)edu
skidrow.tay.dec.com> said:
I vaguely thought that PCA's policies were supposes to include a maximum
interval between the issuance of CRL's so, while you might not know the
most recent one actually issued, you could always demand one no older
than this maximum and disbelieve things till you got it. This
eliminates any secure comm needs.
- - -
Boy, if I were a business that wanted to receive orders over the
internet for quick delivery, the reassurance that I would get from this
statement would really give me a nice warm feeling about how I could be
responsive to my customers and be assured of the full support of the
legal system for any order that I filled based on receiving a PEM order.
How is this any different from the Real World? When you get an order
from someone, how do you know that they aren't bankrupt or about to
run off with the goods or about to withdrawl all their money from
their bank account or, if they purport to be the agent for some
business, that they are still authorized? The answer is that you
don't and there are plenty of scams for which it is very difficult to
get redress through the legal system. Somehow the world survives.
Of course I would have to wait a week (or a month or whatever) to ship
until the next CRL were due, or I would need to get a speedy reassurance
that the certificate were valid, but then how is it that I could be
assured that the CA was responding, or that is was the CA... unless, of
course, it were a secure communications link perhaps?
? The CRL is signed so it makes no difference whether you got it over
a secure comm link or found it on a piece of trampled paper in the
gutter. If you wish to have a policy that you don't execute an order
until you get a CRL with a later date, you can do that. It might not
be too bad if there were some more or less real time way to get a CRL.
Probably the main effect would be that you would go out of business
because of your slower response time to orders than your competitors
and the costs associated with always getting a CRL (not just the tiny
cost of a few network packets but the administrative complexity,
etc.).
Now if you want to require a later CRL on the first order from a
particular customer or maybe the first big order, maybe that would be
reasonable.
Secure comm links don't make any fundamental difference. Let me
repeat that: SECRUE COMM LINKS DON'T MAKE ANY FUNDAMENTAL DIFFERENCE.
What if the keys have been stolen and someone is securely
impersonating the other entity? The answer is, they have agreed to be
bound by those keys, at least until they make a reasonable effort to
disavow them. And how are they going to be sure they have contacted
every possible person to say that the secure comm link keys were
compromised? And how are they going to convince you that the message
of disavowal is genuine and not a denial of serice attack? Use some
higher level key? Get a court order signed by the court's key? And
what if those are compromised?
None of this is really any different from appointing a person as your
agent and them placing orders that bind you and your later revocation
of their power of agency.
This all started as a discusion of the necessity for secure
communications links. Maybe I was confused but, as far as I can see,
as long as you can authenticate and, if desired, encrypt individual
messages, there is no need to secure comm links or channels unless you
are worried about traffic analysis.
There isn't any way to get perfect security in the real world.
Peace ..Tom
Donald