Revised Solution: What if miners claim authorized dust UTXOs through entirely separate, regular, standard-format transactions? Though not economically feasible for single transactions, it becomes extremely beneficial economically when batching multiple dust UTXOs simultaneously, significantly amortizing transaction overhead across many claims. Coinbase transactions remain exactly as they are today, retaining their single-input rule and current consensus constraints.
2. Spending Dust Outputs Without Original Conditions
Concern: The dust outputs marked for claiming by miners can't currently be spent without fulfilling their original conditions, which would require a hard fork to change.
Revised Solution: What if miners are permitted to spend dust UTXOs without their original conditions only under strictly defined new rules:
* The dust UTXO must be explicitly authorized for miner spending through an OP_RETURN-based "Dust Fee Authorization" (DFA) transaction.
*The miner’s transaction claiming this dust must occur in the exact same block as the DFA transaction.
*Only dust UTXOs below a clearly defined threshold (546 sats) are eligible.
These new consensus rules strictly restrict previously impossible spending conditions, making it unequivocally a valid soft fork. No previously illegal behavior is permitted without new restrictive conditions explicitly met.
3. Economic and Practical Viability
Concern: The economic overhead (OP_RETURN transaction plus coinbase input overhead) might be larger than simply spending the dust normally.
Revised Solution: With coinbase inputs no longer altered, the overhead is significantly reduced. Furthermore, the revised mechanism explicitly encourages batching multiple dust authorizations into a single DFA transaction, dramatically amortizing overhead costs across many dust UTXOs. This batching substantially improves economic viability, especially during periods of lower mempool congestion where fees are minimal.
Does this design address your concerns while preserving the original goal of voluntary, secure, and economically rational reclamation of dust UTXOs?
Your insights have been invaluable. I'm eager to receive any further feedback on this revised design.
Thank you again for your careful review and helpful critique.
Best regards,
Hello,
This is not a soft fork, for two reasons:
* Coinbase transactions can only have exactly one input. I don't think there is a particularly good reason for this besides simplicity, but that is the current rule. Allowing a coinbase transaction to additionally also spend certain outputs would require a hardfork.
* The outputs being marked as dust are not allowed to be spent by miners. Changing this requires a hardfork as well. Think about it: if this was possible with a softfork, it must mean that doing what you're proposing would *already be legal* today, and thus not need this proposed change in the first place. Softforks can only outlaw formerly legal behavior.
Furthermore, I don't really see the point. The proposal requires both a coinbase txin to spend the coin, plus a signature in a separate transaction, in the same block. To pay the miner for the opportunity cost of not including normal transactions with these bytes, the fee for this OP_RETURN output should economically be priced at the block's feerate for the size of the OP_RETURN output *plus* the cost of the coinbase transaction input. Together, they are no smaller (and with witness discount, I suspect larger) than the user just spending their "dust" output, and thus the fee for using this OP_RETURN-based mechanism would be larger than the value of the dust output.
--
Pieter
On Saturday, March 8th, 2025 at 1:23 PM, Nighttime Satoshi <nighttimesatoshi@gmail.com> wrote:
> Dear fellow Bitcoin developers,
>
> I'm excited to share a proposal addressing a long-standing Bitcoin challenge: economically unviable dust UTXOs.