[Bitcoin-development] An initial replace-by-fee implementation is now available

John Dillon john.dillon892 at googlemail.com
Thu May 9 09:58:50 UTC 2013

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After some consultation with affected sites by myself and Peter we have decided
to release an initial replace-by-fee implementation and setup a server using
those rules on testnet. This implementation does not include recursive fee
evaluation, and is therefore vulnerable to DoS attack, so hopefully that will
continue to allow adoption to proceed gradually. We can-not recommend mining on
mainnet with it. It does not include an "undo" RPC command or an adjust fees,
and Peter says he has not implemented one yet.  Patches are welcome.

Specifically there were requests from vulnerable parties, which interestingly
included a site that knew they had bugs related to replacement but not
financial vulnerabilities, to put up a server on testnet to check wallet code.
The vulnerable requested to remain undisclosed. An additional consideration was
the upcoming anti-dust rules which are yet another example of why zero-conf is
so much more dangerous to accept than single-conf. Two of the people contacting
us brought up that issue in fact.

The code is on github:


and a replace-by-fee server operating on testnet is available at
testnet-replace-by-fee.bitcoin.petertodd.org To test you will need to use the
raw transaction API and manually create the replacement transaction. Do note
that your wallet will retain the existing one and no mechanism yet exists to
delete the old transaction from your wallet. Again, a certain amount of
"cludgyness" to this is intentional to discourage premature non-testing use.

Regarding the reward, I've decided Peter will collect the full amount even
though the work is not %100 complete (the mempool aspect) due to his concern
about staging an implementation properly, working with vulnerable sites, and
overall genuine interest in the actual issues at hand rather than the reward.
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