Good morning Greg,
> Hi James, > Could you elaborate on a L2 contract where speedy > settlement of the "first part" can be done, while having the rest > take their time? I'm more thinking about time-out based protocols. > > Naturally my mind drifts to LN, where getting the proper commitment > transaction confirmed in a timely fashion is required to get the proper > balances back. The one hitch is that for HTLCs you still need speedy > resolution otherwise theft can occur. And given today's "layered > commitment" style transaction where HTLCs are decoupled from > the balance output timeouts, I'm not sure this can save much. As I understand it, layered commitments can be modified to use `OP_CTV`, which would be slightly smaller (need only to reveal a 32-byte `OP_CTV` hash on the witness instead of a 64-byte Taproot signature, or 73-byte classical pre-Taproot ECDSA signature), and is in fact precisely an example of the speedy settlement style. > CTV style commitments have popped up in a couple places in my > work on eltoo(emulated via APO sig-in-script), but mostly in the > context of reducing interactivity in protocols, not in byte savings per se. In many offchain cases, all channel participants would agree to some pre-determined set of UTXOs, which would be implemented as a transaction spending some single UTXO and outputting the pre-determined set of UTXOs. The single UTXO can be an n-of-n of all participants, so that all agree by contributing their signatures: * Assuming Taproot, the output address itself is 33 bytes (x4 weight). * The n-of-n multisignature is 64 witness bytes (x1 weight). Alternatly the single UTXO can be a P2WSH that reveals an `OP_CTV`: * The P2WSH is 33 bytes (x4 weight) --- no savings here. * The revelation of the `<hash> OP_CTV` is 33 witness bytes (x1 weight). Thus, as I understand it, `OP_CTV` can (almost?) always translate to a small weight reduction for such "everyone agrees to this set of UTXOs" for all offchain protocols that would require it. Regards, ZmnSCPxj _______________________________________________ bitcoin-dev mailing list bitcoin-dev@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
