Subject: Re: [Bitcoin-development] F2Pool has enabled full replace-by-fee

From: Tom Harding <[email-masked]>
Date: Sat, 20 Jun 2015 22:56:13 -0700

On 6/20/2015 5:54 PM, Eric Lombrozo wrote:
> Perhaps it isn’t prudent to push out changes to the relay policy that make these exploits even easier right now - but we NEED to be applying some kind of pressure on the merchant end to upgrade their stuff to be more resilient so that we have more room for changes on things like relay policy without significant disruption to the network.
>

There's no need to worry about causing more problems by relaying
double-spends.  After a year of watching, it's clear that already only
20% of hash power strictly obeys first-seen.

http://i.imgur.com/0bYXrjn.png

It may be surprising that
 - The period of ambiguity is very short - just 2 seconds
   (this makes sense, given the .5s median propagation time)
 - Fast double-spends between 2 and 15 seconds are less successful
 - The steady-state 80% respend success rate is reached after just 15
seconds

The >30s data point includes txes that were respent after a long time,
sometimes months.  Those longer-term respends are to be expected, as
people reclaim stuck txes.

Paying attention to double-spends is an opportunity for wallets and
merchants .  With 140 Bitcoin XT nodes online, you're probably already
receiving them.  Most wallets, including vanilla core, don't even alert
when a double-spend of a wallet transaction appears in a block - even
though there may still be time to withhold delivery of the goods/services.

If FSS RBF gains miner share, fewer successful zero-conf double-spends
will occur.  Only radical twisted logic finds that to be an undesirable
result.