From: Wolfgang Schneider <schneiw(_at_)darmstadt(_dot_)gmd(_dot_)de>
Date: Fri, 13 Jan 1995 22:27:10 +0100
If this is OK for you and your business partner you neither need PEM
nor PGP, but I think you describe a situation which many people would like
to see improved from a security standpoint. I agree with your description
of the advantages of the PGP model over the PEM (1422) model, but the
disadvantage is IMHO that it is only a comparatively slight improvement
over fax. I'm not saying that PGP isn't a great thing to have which offers
reasonable security at low cost for many applications, but I fail to
see how it can provide authenticity in large open communities.
Well, the entities involved in this transaction were the Massachusetts
Institute of Technology, and Datacomm Warehouse (a mail-order catalog
store that sells modems and other telecommunications product).
Actually, PGP can be substanstantially better than fax, and still much
simpler to use that PEM. For example, if MIT has an account set up with
Datacomm Warehouse, Datacomm Warehouse could simply sign an MIT's
purchasing agent's PGP key. Given the overhead necessary to set up an
account (D&B credit checks, et. al.) the additional overhead to sign a
PGP key would be negligible.
Similarily, if I wanted to sign credit slips for Visa, after Visa had
done all of the checks to assure my creditworthiness and set up my
account (which today may include sending in a photography to embed in my
credit card), VISA could also sign my PGP key. Now, if I sign an order
with my PGP key, the vendor with whom I've set up my prior account can
verify my key directly, because that vendor has its own signature on my
key. It doesn't have to depend on the actions of some far-off PCA, or
CA; it can verify using its own key.
Basically, what PEM buys you is the ability to authenticate someone's
public key without needing any sort of pre-arrangement (you just have to
pay the price of all of the legal hair of setting up the CA and PCA
hierarchy). However, I suspect most business tractions have a fair
amount of pre-arrangement done in advance; and in that case, the PGP
model can work for a vendor right away, without needing to wait for the
PEM hierarchy to make its appeareance. And, eventually, if a PGP key is
signed by, say, VISA, perhaps some vendor like Datacomm Warehouse will
be willing to accept VISA's signature, without requiring that it affix
its own signature.
In any case, this is straying from the main topic at hand. I suggest if
we want to discuss this further, that we find a more appropriate venue....
- Ted