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Re: IPSEC requirements
> From: Mark H Linehan/Watson/IBM Research
> - We need authentication of message sources (i.e. of the IP source address &
> related information) so that firewall routers can filter packets based on
> source addresses. I think this is the only requirement that really MUST be
> addressed at the IP level.
>
Whoops! I certainly don't agree with this one!
The end-end communicators want to authenticate the message source
(or the router-router participating in a tunnel), but certainly
routers snooping on end-end authentication is not a goal. Too many keys
floating about.
If we could only get authentication widely deployed, we won't need
firewalls anymore.
> - We need message confidentiality (encryption) for those situations where the
> communicating parties want to keep their messages private. Examples are many
> corporate environments.
>
> This function can be provided at the application level (e.g. by PEM, etc.)
> with the advantage that applications can selectively apply encryption where
> it's really needed. The reason for providing confidentiality at the IP level
> is that many apps don't implement any kind of encryption. Performing
> encryption at the IP level gives a blanket guarantee that all packets are
> private.
>
Here I agree. And of course, tunnel encryption is at the IP level.
> - We need message integrity (i.e. a guarantee that no bits in a packet have
> been changed) for the same reasons that we need message confidentiality.
>
I think that this is _not_ orthogonal to authentication. The integrity
function should simultaneously provide authentication.
Bill.Simpson@um.cc.umich.edu