From rusty at rustcorp.com.au  Thu Nov 22 05:12:54 2018
From: rusty at rustcorp.com.au (Rusty Russell)
Date: Thu, 22 Nov 2018 15:42:54 +1030
Subject: [Lightning-dev] [PATCH] First draft of
	option_simplfied_commitment
In-Reply-To: <8027ECDC-1A1D-4372-856B-388A1A5C58CC@mattcorallo.com>
References: <87bm6jp42a.fsf@rustcorp.com.au>
	<e0c177b5-99ab-4ca9-81e3-3bb53d92d262@bluematt.me>
	<1ea6ecfd-0f17-4aab-44c8-3c3e457cc4d6@bluematt.me>
	<87va4qnj7g.fsf@rustcorp.com.au>
	<8027ECDC-1A1D-4372-856B-388A1A5C58CC@mattcorallo.com>
Message-ID: <8736rtn19l.fsf@rustcorp.com.au>

Matt Corallo <lf-lists at mattcorallo.com> writes:
> Ah, oops, indeed, that is much cleaner :). Still need a CSV of 1, though :(.

OK, let's walk through this:

Locally offered HTLC:
- Local HTLC-Timeout tx is CLTV delayed, but remote can fulfill without delay.
Remote offered HTLC:
- Local HTLC-Success tx can be done without delay, but remote timeout is CLTV.

IOW:
- HTLC output scripts get a `1 OP_CSV OP_DROP` in the non-revoked branch:

    OP_DUP OP_HASH160 <RIPEMD160(SHA256(revocationpubkey))> OP_EQUAL
    OP_IF
        OP_CHECKSIG
    OP_ELSE
 +      1 OP_CHECKSEQUENCEVERIFY OP_DROP
    ...
- HTLC-Success tx needs nSequence = 1.
- Similarly any self-generated fulfullment tx needs nSequence = 1.

Yech.

I still want a new RBF rule where if you pay twice the current package
*feerate* your tx is accepted, overriding RBF rules 3, 4 & 5.  Probably
need to increase the effective minrelay feerate for any txs adding to
that package, similarly (using that double-previous-package-feerate).

That would mean we're back to a single P2WSH(OP_TRUE) with less
blockchain spam, and life is simple.  But I'll debate this on
bitcoin-dev :)

Cheers,
Rusty.