Date: Thu, 07 Oct 2021 04:52:01 +0000
To: Erik Aronesty <erik@q32.com>
From: ZmnSCPxj <ZmnSCPxj@protonmail.com>
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Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>,
 lightning-dev <lightning-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] [Lightning-dev]   Removing the Dust Limit
Precedence: list

Good morning e,

> mostly thinking out loud
>
> suppose there is a "lightweight" node:
>
> 1.  ignores utxo's below the dust limit
> 2.  doesn't validate dust tx
> 3.  still validates POW, other tx, etc.
>
>     these nodes could possibly get forked - accepting a series of valid,
>     mined blocks where there is an invalid but ignored dust tx, however
>     this attack seems every bit as expensive as a 51% attack

How would such a node treat a transaction that spends multiple dust UTXOs a=
nd creates a single non-dust UTXO out of them (after fees)?
Is it valid (to such a node) or not?

I presume from #1 it never stores dust UTXOs, so the node cannot know if th=
e UTXO being spent by such a tx is spending dust, or trying to spend an alr=
eady-spent TXO, or even inventing a TXO out of `/dev/random`.

Regards,
ZmnSCPxj