TYPE 0x0704 · COMPOUND FAMILY

PTLC

Point Time Locked Contract. Combines an adaptor signature verification with a relative timelock (CSV) in a single block. Collapses the ADAPTOR_SIG + CSV two-block pattern for payment channel constructions.

Compound Non-Invertible

Ladder Diagram

Fields

Field	Data Type	Size	Side	Description
timelock	NUMERIC	1-4 B	Conditions	Relative timelock in blocks (BIP 68 sequence value)
pubkey	PUBKEY	32-33 B	Witness	Public key (verified via Merkle leaf)
signature	SIGNATURE	64-65 B	Witness	Adapted Schnorr signature
preimage	PREIMAGE	32 B	Witness	Adaptor secret (scalar preimage of the adaptor point)

Both public keys folded into Merkle leaf via merkle_pub_key (PubkeyCountForBlock = 2). No key fields in conditions.

Evaluation Logic

1. Verify witness PUBKEY against Merkle leaf (merkle_pub_key). If mismatch → UNSATISFIED

2. Verify adaptor SIGNATURE against PUBKEY and adaptor point. If invalid → UNSATISFIED

3. Verify CheckSequence(timelock). If fails → UNSATISFIED

4. All checks passed → SATISFIED

Return Values

Condition	Result
Missing required fields	ERROR
Merkle leaf verification fails	UNSATISFIED
Adaptor signature verification fails	UNSATISFIED
CSV sequence check fails	UNSATISFIED
Adaptor sig valid AND timelock elapsed	SATISFIED

JSON Wire Format

Conditions (scriptPubKey)

{
  "type": "PTLC",
  "inverted": false,
  "fields": [
    { "type": "PUBKEY", "hex": "02abc1...33 bytes" },
    { "type": "PUBKEY", "hex": "03def2...33 bytes" },
    { "type": "NUMERIC", "value": 144 }
  ]
}

Witness (input)

{
  "type": "PTLC",
  "inverted": false,
  "fields": [
    { "type": "PUBKEY", "hex": "02abc1...33 bytes" },
    { "type": "SIGNATURE", "hex": "e4f2a1...64 bytes" },
    { "type": "PREIMAGE", "hex": "b7c8d9...32 bytes" }
  ]
}

Use Cases

Scriptless Payment Channels

PTLC replaces HTLCs in payment channels, using adaptor signatures instead of hash locks. The spending transaction reveals the adaptor secret, enabling the counterparty to claim on the other side without on-chain hash preimage exposure.

Privacy-Preserving Routing

Unlike HTLC-based routing where the same hash appears across all hops, PTLC routing uses different adaptor points per hop. This prevents correlation attacks across the payment path.

← HASH_SIG CLTV_SIG →