I genuinely believed that we had reached the lowest point concerning Bitcoin enthusiasts presenting irrational and absurd arguments against enhancements to Bitcoin, in an attempt to depict themselves as some sort of virtuous underdog opposing corruption and incompetence from within.
How mistaken I was.
First, some elements to clarify. With Lightning channels, you must determine your fee-rate for a unilateral closure transaction beforehand. Since the actual UTXO is a multisig, both individuals in the channel need to endorse the transactions either party utilizes to unilaterally close the channel ahead of time. The whole security of Lightning hinges on these aspects. If you ever find yourself needing to rely on one, say due to your counterpart being uncooperative, you can’t simply depend on them to re-sign one at a higher fee-rate if needed.
This created difficulties during unilateral fee closures. If fees were elevated and decreased after you initiated your channel, you incur costs you didn’t have to pay. Conversely, if fees were low and increased, you can’t ensure that your channel closes promptly. You can’t Replace-By-Fee (RBF) because your counterpart needs to sign, and you can’t utilize Child-Pays-For-Parent (CPFP) as all your outputs are time-locked, so nothing utilizing them will be valid until after the first transaction actually confirms and several blocks pass.
Due to this, anchor outputs were created. They were unique outputs available without timelocks solely to facilitate expenditure in a child transaction to fee-bump the Lightning closure transaction. However, these introduced further capital inefficiency, necessitating a considerable amount of satoshis to generate these outputs.
Introducing ephemeral anchors, which build on the v3 transaction relay and package relay (conveying transactions in the mempool as groups). The concept is to possess a 0 value output that can be spent using OP_TRUE (indicating anyone can spend it). Transactions with a fee-rate of 0, that include an ephemeral anchor, will be relayed in the mempool as long as there is a child transaction spending the ephemeral anchor output with an appropriate fee-rate.
This permits Lightning channels to endorse unilateral closure transactions without fees, and anyone needing to utilize them can easily spend the ephemeral anchor output to establish whatever fee-rate is necessary at the moment. This significantly streamlines Lightning closure transactions and eradicates the capital inefficiencies of existing anchor outputs. An additional advantage is that anyone can fee bump a transaction with an ephemeral anchor, not just the channel (or other contract) proprietors.
The ephemeral anchor never actually establishes the 0 value UTXO in the UTXO set, as it will only be relayed together with a transaction that instantly spends it in the same block.
So, why is this a concern? Or an attack? I have no idea; it’s a remarkable simplification that virtually any second layer protocol, or contract built on Bitcoin in general, utilizing pre-signed transactions will greatly benefit from. It induces no bloat in the UTXO set because, as implied in the term, the outputs used are ephemeral. They aren’t actually permanently established.
The only contentions I’ve encountered are “spam!” Or “Core developers are eliminating the dust limit!” (A limitation on the minimum value transaction outputs must possess to be relayed, and they aren’t abolishing it for anything but ephemeral anchors, which must be immediately spent by a child to be relayed).
I believe we have arrived at a juncture where we must seriously contemplate when it is appropriate to disregard criticism or grievances regarding technical subjects in this arena. Or when valid criticisms cease to be so and transform into irrational and illogical crusades against or for personalities rather than reasoned critiques. Because this backlash against ephemeral anchors is undeniably the latter.
All logical criticism should be embraced in an open-source protocol like Bitcoin, but it’s time to cease indulging irrational tribalism lacking logical foundation as if it were equivalent to valid criticism. It’s not; it’s simply a waste of time and a Denial of Service attack against the process of enhancing Bitcoin.
This article is a Take. Perspectives expressed are solely those of the author and do not necessarily reflect those of BTC Inc or Bitcoin Magazine.