CTV + CSFS: a letter
Jun 9 - Jun 28, 2025
- The letter published advocates for the activation of OP_CHECKTEMPLATEVERIFY (BIP-119) and OP_CHECKSIGFROMSTACK (BIP-348), highlighting their potential to enhance Bitcoin's value as a scarce, censorship-resistant asset.
These opcodes, which have been extensively reviewed and are considered safe and in demand, could unlock a wide array of functionalities including scaling solutions, vaults, congestion control, non-custodial mining, discreet log contracts, and more. CTV, introduced over five years ago, remains the preferred method for enforcing pregenerated transaction sequences through consensus. CSFS, utilized in Blockstream’s Elements for about eight years, complements CTV by enabling implementations like ln-symmetry for Lightning Network improvements among other use cases.
The letter requests Bitcoin Core contributors to prioritize reviewing and integrating these opcodes within six months, emphasizing that this timeline would allow for thorough review and planning for activation. It clarifies that the request is not to dictate the consensus process but acknowledges the necessity of implementing these changes in the most widely used Bitcoin client before activation. The signatories, representing a broad spectrum of application and protocol developers, express optimism about the benefits these changes could bring to Bitcoin users, especially regarding security and scaling. They believe that the minimal size and scope of these changes make them a realistic step forward in preserving Bitcoin’s promise.
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