{"type":"rich","version":"1.0","author_name":"npub1g5zswf6y48f7fy90jf3tlcuwdmjn8znhzaa4vkmtxaeskca8hpss23ms3l","author_url":"https://nostr.ae/npub1g5zswf6y48f7fy90jf3tlcuwdmjn8znhzaa4vkmtxaeskca8hpss23ms3l","provider_name":"njump","provider_url":"https://nostr.ae","html":"📅 Original date posted:2022-04-25\n📝 Original message:Good morning Zac,\n\n\u003e On Mon, 25 Apr 2022 at 07:36, ZmnSCPxj \u003czmnscpxj at protonmail.com\u003e wrote\n\u003e\n\u003e \u003e CTV *can* benefit layer 2 users, which is why I switched from vaguely apathetic to CTV, to vaguely supportive of it.\n\u003e\n\u003e\n\u003e Other proposals exist that also benefit L2 solutions. What makes you support CTV specifically?\n\nIt is simple to implement, and a pure `OP_CTV` SCRIPT on a P2WSH / P2SH is only 32 bytes + change on the output and 32 bytes + change on the input/witness, compared to signature-based schemes which require at least 32 bytes + change on the output and 64 bytes + change on the witness ***IF*** they use the Taproot format (and since we currently gate the Taproot format behind actual Taproot usages, any special SCRIPT that uses Taproot-format signatures would need at least the 33-byte internal pubkey revelation; if we settle with the old signature format, then that is 73 bytes for the signature).\nTo my knowledge as well, hashes (like `OP_CTV` uses) are CPU-cheaper (and memory-cheaper?) than even highly-optimized `libsecp256k1` signature validation, and (to my knowledge) you cannot use batch validation for SCRIPT-based signature checks.\nIt definitely does not enable recursive covenants, which I think deserve more general research and thinking before we enable recursive covenants.\n\nConceptually, I see `OP_CTV` as the \"AND\" to the \"OR\" of MAST.\nIn both cases, you have a hash-based tree, but in `OP_CTV` you want *all* these pre-agreed cases, while in MAST you want *one* of these pre-agreed cases.\n\nWhich is not to say that other proposals do not benefit L2 solutions *more* (`SIGHASH_ANYPREVOUT` when please?), but other proposals are signature-based and would be larger in this niche.\n\nRegards,\nZmnSCPxj"}