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Re: proposed IPSEC changes/extensions
> C: If "crypto period" or "SA life time" is an SA parameter, should they
> be negotiated by key management protocol ? Perhaps as an attribute of a
> transform in ISAKMP ?
Definitely. the current isakmp-05 draft says:
In particular, key lifetimes and SA lifetimes are purely a local
issue, and should not be negotiated.
I think this is *very* wrong. It means that a receiver can terminate
an SA while the sender still thinks its valid... this will set off
false alarms when incoming traffic fails to decrypt/verify, and freeze
user traffic for several RTT's while the key mgmt protocols try to
resynchronize. Very clumsy..
Note that negotiating a lifetime for the SA does *NOT* require
synchronized clocks; all it requires is a clock on each end with
frequency accurate to within a couple percent.
ISAKMP currently handles SA removal with explicit DELETE messages, but
it would be more efficient, in general, to let idle SA's expire
without the need to send messages (consider demand-dial links .. you
probably want the SA to live longer than the demand-dial idle timeout,
and it would be silly to bring the link up just to send a DELETE
message..).
- Bill