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Re: Naming 1: granularity

> This is the first of two related messages that I don't want to send --
> or rather, that I probably don't want to see the end of the threat that
> they may generate, since I've *never* seen a naming discussion that was
> at all pleasant.  That said, the issue has to be raised...
> 
> The basic question is this:  when we do a key management exchange -- and
> I realize that we haven't yet agreed on how to -- the two negotiators
> have to know names for the parties involved.  In the case of two end hosts
> negotiating, the name should (but see the next message) refer to the
> hosts themselves.  Should these names be IP addresses or domain names?

In My HuMble Opinion, they should be both.  That is, a host should have
a certificate with its IP address and its hostname.  In the case of
multiple IP addresses or hostnames, multiple certificates.  E.g. if I
talk to "ftp.cdrom.com", I should use the "ftp.cdrom.com" certificate,
AND not the wcarchive.cdrom.com or the 192.216.191.11 certificate.

There was a paper in the IPv6 discussion advocating separate IP addresses
for the various aliases of a machine, which seems reasonable to me for similar
reasons.  Computers have multiple personalities, and it seems reasonable
to give them each a different key.

(Indeed, it's also reasonable for "LabmdaMOO" to have a key, independent
of the host it's running on.)

> But that's not the hard case.  The hard case is when one party's
> cryptographic functions are performed by a crypto gateway, which protects
> a whole group of machines.  Should this gateway use its own name?  Then
> how does the remote end know it speaks for the real destination?  Should
> the certificate for the crypto gateway contain a list of addresses?  A
> list of address/mask pairs?  A list of names?  We cannot do gateway-to-host
> or gateway-to-gateway encryption till we settle these and related issues.

Because the gateway has the real destination's key.  The destination,
by giving the gateway its key, is trusting the gateway to do right by it.

Are there big performance wins for having the gateway have just one key?
You could put multiple names (like all the hosts it protects) on the one
key, I guess.

It does maean that a gateway has to know about the domain names of each of
the machines it guards.  (Or you could have a ".cdrom.com" key, maybe?)
-- 
	-Colin