From: James Ferguson <jamesfergusonch@gmail•com>
To: Pieter Wuille <bitcoin-dev@wuille•net>
Cc: Bitcoin Development Mailing List <bitcoindev@googlegroups.com>
Subject: Re: [bitcoindev] OP_KEEPCHANGE - mitigating dust outputs
Date: Thu, 26 Sep 2024 11:05:01 +0200 [thread overview]
Message-ID: <CABCM42TOD8fOJhy-1xEhGHiW3W9-MBnrhcHLOvsNwkjSiaG0VA@mail.gmail.com> (raw)
In-Reply-To: <4_re7EWb0zy-E_Yk472AGf4WwgwxO9XCC1Y2RqYGlCV7FXpbq1ifIe-DL93-y5erlsAO_G-27SzLcFhGq9kDs8KNE0u2GSC24cFV-rJ5X10=@wuille.net>
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Pieter
- Thank you, very helpful explanation
So suggestion sucks - I withdraw it to avoid wasting others time !
However, it seems dust benefits could be achieved simply by wallets
proposing dust roundup to recipient when creating the transaction rather
than providing a change output - It seems wallet providers could automate
this small benefit to be adopted with no protocol change.
So it fair to describe dust as a "tragedy of the commons" (wallets leave
value at small cost but no benefit) that bloats the time chain ?
Thanks for your assistance - I want to get into this but need to pick a
niche to grow initial understanding. - Suggestions welcome
Cheers, James
On Thu, 26 Sept 2024 at 03:23, Pieter Wuille <bitcoin-dev@wuille•net> wrote:
> Hi James,
>
> I believe you're imagining that Bitcoin works very differently from how it
> actually does. Comments below inline.
>
> On Wednesday, September 25th, 2024 at 8:44 PM, James Ferguson <
> jamesfergusonch@gmail•com> wrote:
>
> Introduction of provisionally named "OP_KEEPCHANGE" allows small residual
> UTXO (change) to be automatically credited to the primary recipient’s
> address.
>
>
> Bitcoin doesn't have a concept of address balances at the protocol level,
> or even addresses at all, let alone a "primary recipient address". Balances
> you see in wallets and blockchain explorers simply report the sum of the
> values of UTXOs under control of a given address, but this is a local
> interpretation made by that software; the protocol itself does not know or
> care about these things.
>
> The way to "credit an address" in Bitcoin is literally to create a UTXO
> locked with (the script corresponding to) the address in question, so
> barring an extremely invasive overhaul of how the entire protocol works,
> there isn't actually any UTXO set size benefit to this proposal - change
> UTXOs would still need to be created. In addition, if your proposal
> requires revealing what the recipient of a payment is (as "crediting
> primary recipient" implies), it would necessarily also undo the primary
> privacy benefit of having a UTXO model in the first place: today, one
> cannot generally tell which output of a transaction is the payee, and this
> is by design.
>
> Of course, a hypothetical proposal could change anything about Bitcoin's
> design if it were to have enough support. If the Bitcoin ecosystem really
> wanted an address balance model, nothing prevents the introduction of that.
> In that case, there is no point to have UTXOs, or change, at all. Just make
> transaction deduct some address balances, and credit some others directly.
> This removes many of the issues you seem to want to address much more
> directly (including coin selection, dust accumulation, UTXO set growth to
> some extent, and many more, while adding other complications in other
> places, of course). However, it would also massively hurt privacy, as there
> would be an on-chain cost to creating new addresses/balances, incentivizing
> keeping one's funds in just one. The current UTXO model does not care about
> the distinction between payments and change and this is very much
> desirable: sending your change to a new change address with pristine
> history costs exactly the same as sending it back to the address the spend
> coins were assigned to.
>
> b) Enhanced Privacy: .
> This provides a slight improvement in transaction privacy by obfuscating
> the typical patterns used to identify change outputs.
>
>
> But it does so at the cost of incentivizing not transitioning to a new
> address on every transaction, a huge privacy leak.
>
> - When used in a transaction, `OP_KEEPCHANGE` signals that any excess
> change be added to the primary output instead of generating a separate
> change output.
>
>
> Change does not exist at the protocol level. It is just an output like any
> normal payment output, and indistinguishable from it. The protocol also has
> no knowledge of excess - that is a concept purely local to the sender
> wallet. It *chooses* to add an output back to itself, to balance the
> amounts in the inputs with the amounts in the outputs (minus fee). At the
> very least your proposal would require a way to signal how much to send
> back, and to where (remember that multiple parties can cooperate to jointly
> construct a single transaction!). At this point you're not far off from
> just having another output...
>
> Cheers,
>
> --
> Pieter
>
>
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prev parent reply other threads:[~2024-09-26 9:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-26 0:44 James Ferguson
2024-09-26 1:22 ` Pieter Wuille
2024-09-26 9:05 ` James Ferguson [this message]
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