[noise] Stricter rules #1: replacing public keys

[Alex]

On Thu, 21 Apr 2016 14:47:26 -0700
Trevor Perrin <trevp at trevp.net> wrote:

> So I lean towards clarifying:
>  - only one new ephemeral can be sent during a Noise protocol (which
> might replace a semi-ephemeral)

Sounds good to me.

>  - the static public key cannot change during a Noise protocol

I could have sworn that a previous draft of the spec included language
which prohibited overwriting a remote static key. Either way I already
throw an exception if it occurs.

-- 
Alex