Amir,

picking up a debate earlier this month around the forthcoming
paper on spoofing:

http://www.cs.biu.ac.il/~herzbea//Papers/ecommerce/spoofing.htm

Amir Herzberg wrote:
> I still don't see why the same corporation needs multiple SSL
> certificates. Why??
> ...

On this one point - I'm unsure whether you are asking from
a practical pov or an ideal pov.

Practically speaking, certs are required for each different
domain name.  There is supposed to be some wildcarding
in place such that *.mydomain.com is covered, but it doesn't
work so well, apparently.  This may be historical, it may be
that browsers now all handle the wildcarding, but maybe not,
as a) I've heard complaints about it not working well enough,
and b) I've seen sites that still duplicate certs for each
different subdomain (my pair web mail has a cert per host
for web1.pair.com, etc...).

In practical terms, any large corporation uses domains as labels
that are cheap and makes them into brands.  So, for example, I
have idea_one.org and biz_two.com.  Now, both of these require
certs.  They are both my corp, but I have to get a cert for
each.  Even if they are the same site, but with a different
domain name (to re-brand the same thing) I still need more
than one cert.

Likewise, even within a single-named secure operation, there
are always duplicates of a site.  For example, there are older
copies, there are test rigs, development rigs, and failovers.
In the banks that I know, the common thing is for them to
have 4 running systems for everything.  Each is a different
role:  production, test, development and something else I
forget.

Now, each requires web access and a domain.  It would be
plausible to use the same cert in each, but that means they
also have to be secured the same way.  Much better to create
a separate cert for each one, and that way if the test site
gets compromised, it matters not.  This frees the test system
to run on its own security regime, and get on with the serious
business of testing.

In structural terms, I think one reason why corporations require
many certs is that it was set up that way by the originators of
the x.509-based PKI software.  If you read through for example
Lynn Wheeler's historical comments, you will see repeated
references to "viable revenue model" which amounts to "we
scotched that because we couldn't sell it."  Recall back in
the mid 90s, there was huge hope put on the SSL server for
Netscape as it had finally found a product to sell.

So, I think it's fair to say that the original architects
deliberately or subconsciously encouraged a situation where
bigger companies could be sold more certs.  For money of
course.  The fact that this had little to do with security
or with the needs of the corporation was lost at the time.
This is almost certainly the reason why Netscape didn't
set out selling software for each corporation to run its
own CA internally - that would have reduced the "pretended"
market size for certs to something unviable, on paper.

Theoretically, just to repeat my earlier fundamental point,
I don't see the point in having a corporation bound to one
cert.  They are not bound to one car, one building, one set
of letterheads, or one secretary .. what's the deal with
one cert?

The only thing that a corporation is bound to singly that
I can think of is the rules listed by the incorporations
act and the tax people.  There should be one corporate seal,
for example.  The consequence of this is of course certainly
in the english common world, the corporate seal is unused,
because it is too hard to find "the one."  Likewise, anything
that is "one only" is generally bypassed in real business.


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