[Bitcoin-development] replace-by-fee v0.10.0rc4

Sun Feb 22 13:53:23 UTC 2015

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On 22 February 2015 08:41:56 GMT-05:00, Eric Lombrozo <elombrozo at gmail.com> wrote:
>In case it wasn't clear in my earlier post, there's of course a third
>possibility - namely, some outputs are kept but not all. Here, it is
>generally impossible to tell whether the motivation was fee
>replacement,
>output replacement, or both. My proposal is to always treat these
>instances
>as output replacement and punish the sender. The sender needs to make
>it
>unambiguously clear it's only a fee replacement by creating a new
>transaction that produces an output with the desired extra fee and then
>adding an input that spends it to the original transaction.

That's a really old idea - I proposed it about two years ago. The optimal way is to allow any txout to be replaced with one with an equal or greater nValue and same scriptPubKey, as well as additional txouts added. (obviously so long as none are removed)

Alas, there's lots of situations where this restricts you from doing useful things, for instance collapsing multiple payments into one by repeated updating to reduce tx size. Equally the benefit is marginal at best given how insecure unconfirmed transactions are - breaking what is already broken isn't a negative.