Date: Sat, 21 Aug 2021 03:10:46 +0000
To: Jeremy <jlrubin@mit.edu>
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 Jeremy,

> one interesting point that came up at the bitdevs in austin today that fa=
vors remove that i believe is new to this discussion (it was new to me):
>
> the argument can be reduced to:
>
> - dust limit is a per-node relay policy.
> - it is rational for miners to mine dust outputs given their cost of main=
tenance=C2=A0(storing the output potentially forever) is lower than their i=
mmediate reward in fees.
> - if txn relaying nodes censor something that a miner would mine, users w=
ill seek a private/direct relay to the miner and vice versa.
> - if direct relay to miner becomes popular, it is both bad for privacy an=
d decentralization.
> - therefore the dust limit, should there be demand to create dust at prev=
ailing mempool feerates, causes an incentive to increase network centraliza=
tion=C2=A0(immediately)
>
> the tradeoff is if a short term immediate incentive to promote network ce=
ntralization is better or worse than a long term node operator overhead.

Against the above, we should note that in the Lightning spec, when an outpu=
t *would have been* created that is less than the dust limit, the output is=
 instead put into fees.
https://github.com/lightningnetwork/lightning-rfc/blob/master/03-transactio=
ns.md#trimmed-outputs

Thus, the existence of a dust limit encourages L2 protocols to have similar=
 rules, where outputs below the dust limit are just given over as fees to m=
iners, so the existence of a dust limit might very well be incentivize-comp=
atible for miners, regardless of centralization effects or not.


Regards,
ZmnSCPxj