On 07/06/2023 12:22 PM, alicexbt via bitcoin-dev wrote: > 1) Register input in A > 2) Double spend same input with zero fee to your own address > 3) Register unconfirmed UTXO from 2 in B
Why would unconfirmed inputs be accepted in a coinjoin? That seems unsafe, regardless of package relay. The sender of the unconfirmed transaction can already replace it thereby pinning or otherwise invalidating the coinjoin, it doesn't need package relay. Furthermore, the coordinator B shouldn't accept the unconfirmed UTXO from 2 because it doesn't even know about that unconfirmed transaction. It has zero fee, so it's not going to be relayed. Conceivably a similar attack can already be done by simply registering the same UTXO with multiple coordinators anyways. This doesn't require package relay either. *** Package relay should help coinjoins since any one of the participants can rebroadcast the coinjoin with a further CPFP if the coinjoin is below the minimum relay fee. Some of the upcoming package RBF proposals should also help by allowing other child transactions in the package to RBF the entire thing, thereby resolving the need to have everyone re-sign the coinjoin in order to RBF. Andrew _______________________________________________ bitcoin-dev mailing list bitcoin-dev@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
