Covenants with OP_TEMPLATEHASH and OP_CHECKSIGFROMSTACK
summary
Proposal BIP 448 adds three Tapscript opcodes to get both next-transaction commitments and rebindable signatures: template hash (pushes the transaction template hash), checksigfromstack (verifies a signature over that template), and internal key (reuses the taproot internal pubkey). Construction targets both CTV and APO use cases, yields a 68‑byte three‑opcode script for rebindable sigs, matches APO efficiency there and is one weight‑unit larger than CTV for commitments, and has a working proof‑of‑concept integrated into Ark and live on an Inquisition signet faucet.
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chapters (9)
- 0:00Covenant proposals intro
- 5:41History of covenant proposals
- 8:50Motivation for OP_TEMPLATEHASH and OP_CHECKSIGFROMSTACK
- 13:26OP_CHECKSIGFROMSTACK for signatures
- 16:33BIP 448 with three new opcodes
- 23:13Block space efficiency comparison
- 26:20Next steps for BIP 448
- 29:53Ark protocol with template hash
- 33:03Q&A
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