Subject: Re: [bitcoin-dev] tx max fee

From: [email-masked]
Date: Wed, 10 May 2023 18:19:01 +0200

> possible to change tx "max fee"  to output amounts?

Is it possible? Yes. Should we do that? My first thought was "maybe", but after thinking more about it, I would say "no", here is why:

Starting point: 1 BTC on some output.
Current situation: A single transaction moving 0.99999000 BTC as fees, and creating 1000 satoshis as some output (I know, allowed dust values are lower and depend on address type, but let's say it is 1k sats to make things simpler).

And then, there is a room for other solutions, for example your rule, mentioned in other posts, like this one: https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2023-May/021626.html

> probably easier just to reject any transaction where the fee is higher than the sum of the outputs

Possible situation after introducing your proposal, step-by-step:

1) Someone wants to move 1 BTC, and someone wants to pay 0.99999000 BTC as fees. Assuming your rules are on consensus level, the first transaction creates 0.5 BTC output and 0.5 BTC fee.
2) That person still wants to move 0.5 remaining BTC, and still is willing to pay 0.49999000 BTC as fees. Guess what will happen: you will see another transaction, creating 0.25 BTC output, and paying 0.25 BTC fee.
...
N) Your proposal replaced one transaction, consuming maybe one kilobyte, with a lot of transactions, doing exactly the same, but where fees are distributed between many transactions.

Before thinking about improving that system, consider one simple thing: is it possible to avoid "max fee rule", no matter in what way it will be defined? Because as shown above, the answer seems to be "yes", because you can always replace a single transaction moving 1 BTC as fees with multiple transactions, each paying one satoshi per virtual byte, and then instead of consuming around one kilobyte, it would consume around 1 MvB per 0.01 BTC, so 100 MvB per 1 BTC mentioned in the example above.

On 2023-05-08 13:55:18 user Erik Aronesty via bitcoin-dev <[email-masked]> wrote:
possible to change tx "max fee"  to output amounts?

seems like the only use case that would support such a tx is spam/dos type stuff that satoshi warned about

its not a fix for everything, but it seems could help a bit with certain attacks