[noise] Negotiation and 0-RTT

[Trevor Perrin]

On Fri, Jul 7, 2017 at 7:24 PM, Alexey Ermishkin <scratch.net at gmail.com> wrote:
> Seems reasonable, lgtm. However we might expect some servers just to drop connections instead of explaining anything

My hope is we could convince servers that on encountering an
unrecognized client_version they should send server_version=FFFFFFFF,
giving the client a chance to try again (or close the connection).

Untested mechanisms like this often don't work when you need them.
And in general this shouldn't be needed, since clients should only
send recognizable client_version (using negotiation_data to offer
upgrades, and using 0-RTT encryption only with servers they know to
support it).

However, if we could get servers to do this, they'd have a little more
future-proofing.

I'd be inclined to try specifying it, and see what happens.

Trevor