From aj at erisian.com.au  Wed Oct 21 03:43:10 2015
From: aj at erisian.com.au (Anthony Towns)
Date: Wed, 21 Oct 2015 13:43:10 +1000
Subject: [Lightning-dev] daemon/p2p protocol
In-Reply-To: <87eggpf2jy.fsf@rustcorp.com.au>
References: <20151016205355.GA18796@navy> <20151019053003.GB19146@navy>
	<CAE8CtV=sfMQ_HU-rtA5V9w6xd-92tKxtQdoJypNHCKa+qZHJqw@mail.gmail.com>
	<20151019220909.GB18268@navy> <87eggpf2jy.fsf@rustcorp.com.au>
Message-ID: <20151021034310.GA22898@navy>

On Wed, Oct 21, 2015 at 11:41:45AM +1030, Rusty Russell wrote:
> Having a session nonce does help after first handshake, though it allows
> correlation, so it needs to change (pretty trivial, it could just be
> sha256() of some shared secret plus a number which increments on each
> successful handshake).

Can just be the first 4-8 bytes of that too (leaving the next 4-28 bytes
to be the secret response in the signature). ECDH of the node ids would
be the obvious shared secret to use as a base?

> In practice I think "successful handshake" is a bit vague, so may
> require allowing +/- 1 nonce.  I'd have to think harder about this
> though.
> Is this overcomplicating things?

While nodes are publishing their ids (and IPs -- even if only by /whois)
in a public IRC channel, I don't think a nonce does any good -- the info
it's trying to avoid revealing is already being revealed anyway. So I
think table this for now?

Cheers,
aj