CheckTemplateVerify (CTV)

OP_CHECKTEMPLATEVERIFY (CTV) is the proposed Bitcoin Script opcode at the heart of BIP-119. Its job: enforce that a spending transaction matches a pre-committed template - a specific set of inputs, outputs, sequences, and locktimes.

How CTV would work at the script level:

1. When you fund a UTXO, the locking script commits to a hash of a transaction template - "to spend this, the spending transaction must hash to value H."
2. The template specifies things like: how many outputs, what amounts, what scripts those outputs use, what relative locktime the spend requires.
3. When someone tries to spend, CTV checks the spending transaction against that template. If it matches, the spend is allowed. If not, it's rejected.

This is one specific way to add covenants to Bitcoin. It's deliberately limited: CTV doesn't let scripts read arbitrary properties of spending transactions, only check them against a precomputed template hash. This limit is part of what makes CTV a smaller-surface-area proposal than some alternatives.

Practical applications if it activated:

• Vaults with forced multi-step withdrawal paths.
• Channel factories that open many Lightning channels from one on-chain transaction.
• Payment pools for batching many recipients efficiently.
• Cold-storage protections against catastrophic hot-wallet compromise.

CTV is one of several covenant designs being discussed. Alternatives include OP_VAULT, OP_CAT (re-enabled), OP_CSFS, ANYPREVOUT (Eltoo's primitive), and Taproot-Trees-based approaches. Different proposals have different tradeoffs on expressiveness, complexity, and future flexibility.

As of 2026, no covenant opcode has activated. See Covenants for the broader debate and BIP-119 for the specific proposal.