Subject: Re: [bitcoin-dev] Unenforceable fee obligations in multiparty protocols with Taproot inputs

From: Peter Todd <[email-masked]>
Date: Tue, 7 Feb 2023 14:04:00 -0500

On Tue, Feb 07, 2023 at 01:35:12PM -0500, Russell O'Connor via bitcoin-dev wrote:
> There is a bug in Taproot that allows the same Tapleaf to be repeated
> multiple times in the same Taproot, potentially at different Taplevels
> incurring different Tapfee rates.
> 
> The countermeasure is that you should always know the entire Taptree when
> interacting with someone's Tapspend.

Another countermeasure could be to implement RBF on taproot witnesses, allowing
transactions with deeper, less efficient, tapleaf scripts to be replaced with
shallower, more efficient, tapleafs. If implemented by giving your peer some
kind of delta encoded update, the bandwidth efficiency may be sufficient to
always allow such updates.

-- 
https://petertodd.org 'peter'[:-1]@petertodd.org