TYPE 0x0301 · COVENANT FAMILY

CTV

CheckTemplateVerify (BIP-119). Verifies the spending transaction matches a committed template hash. The template hash covers version, locktime, scriptSigs hash, input count, sequences hash, output count, outputs hash, and input index. No witness data required — the template is computed directly from the transaction.

Covenant Invertible

Ladder Diagram

Fields

Field	Data Type	Size	Side	Description
template_hash	HASH256	32 B	Conditions	BIP-119 template hash commitment. Covers version, locktime, scriptSigs, input count, sequences, output count, outputs, and input index.

No witness fields required — the template hash is computed directly from the spending transaction context.

Wire Format Breakdown

0x0301 0 1 HASH256 · 34B Conditions = 38 bytes

0x0301 0 0 Witness = 4 bytes (empty block)

Total 44 bytes

Evaluation Logic

1.Read template_hash from HASH256 field. If missing or not exactly 32 bytes → ERROR

2.If no transaction context available → UNSATISFIED

3.Compute ComputeCTVHash(tx, input_index) from spending transaction fields

4.If computed hash == committed template_hash → SATISFIED

5.Otherwise → UNSATISFIED

Return Values

Condition	Result
HASH256 field missing or not 32 bytes	ERROR
No transaction context	UNSATISFIED
Computed hash does not match committed hash	UNSATISFIED
Computed hash matches committed hash	SATISFIED

JSON Wire Format

Conditions (template hash for a 2-output batch payout)

{
  "type": "CTV",
  "inverted": false,
  "fields": [
    { "type": "HASH256", "value": "a1b2c3d4e5f6...32-byte-hex..." }
  ]
}

The template hash commits to the exact shape of the spending transaction. Any deviation in version, locktime, outputs, or input index will produce a different hash and fail evaluation.

Worked Example

Congestion control: batch payout from a single UTXO

UTXO locked with CTV template hash committing to 10 outputs

Spender constructs tx with version=2, locktime=0, 10 outputs to specific addresses

ComputeCTVHash(tx, 0) = a1b2c3d4...

Committed hash = a1b2c3d4... → match → SATISFIED

If attacker changes any output address or amount: hash mismatch → UNSATISFIED

Use Cases

Congestion Control

Batch presigned outputs into a single UTXO during fee spikes. The CTV hash commits to the exact set of recipients, allowing trustless expansion when fees drop. One on-chain transaction becomes many without any signature required.

Vaults

Pre-committed recovery paths where the spending transaction shape is fixed at vault creation time. The CTV hash ensures funds can only move to the pre-determined recovery address with the pre-determined amounts.

Payment Pools

Multi-party payment pools where each participant has a CTV-committed exit transaction. The pool can be unilaterally exited by any participant using their pre-committed template, without cooperation from other pool members.

← TAGGED_HASH VAULT_LOCK →