TYPE 0x0901 · LEGACY FAMILY

P2PK_LEGACY

Legacy P2PK (pay-to-public-key) wrapped as a typed Ladder Script block. Same evaluation as SIG — Merkle leaf pubkey verified, then signature check. Closes arbitrary data surfaces.

Legacy Non-Invertible

Ladder Diagram

Fields

Field	Data Type	Size	Side	Description
scheme	SCHEME	1 B	Conditions	Signature scheme identifier (optional, 0x00 = Schnorr default)
pubkey	PUBKEY	32-33 B	Witness	Public key (x-only 32B or compressed 33B)
signature	SIGNATURE	64-65 B	Witness	Signature over the transaction sighash

Public key folded into Merkle leaf via merkle_pub_key (PubkeyCountForBlock = 1). No key field in conditions.

Wire Format Breakdown

Conditions side (in scriptPubKey):

0x0901 0 2 SCHEME · 1B = 7 bytes

Witness side (in input witness):

0x0901 0 2 PUBKEY · 33B SIGNATURE · 64B = 105 bytes

Total (conditions + witness) 144 bytes

With rung overhead included. Compressed pubkey (33B) case.

Evaluation Logic

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

2. Route by SCHEME field (Schnorr / ECDSA / PQ). Default is Schnorr.

3. Verify SIGNATURE against PUBKEY. If invalid → UNSATISFIED

4. Signature valid → SATISFIED

Return Values

Condition	Result
Missing PUBKEY or SIGNATURE	ERROR
Merkle leaf pubkey count mismatch	ERROR
Merkle leaf verification fails	UNSATISFIED
Signature fails	UNSATISFIED
Signature valid	SATISFIED

JSON Wire Format

Conditions (scriptPubKey)

{
  "type": "P2PK_LEGACY",
  "inverted": false,
  "fields": [
    { "type": "PUBKEY", "hex": "02abc1...33 bytes" },
    { "type": "SCHEME", "hex": "01" }
  ]
}

Witness (input)

{
  "type": "P2PK_LEGACY",
  "inverted": false,
  "fields": [
    { "type": "PUBKEY", "hex": "02abc1...33 bytes" },
    { "type": "SIGNATURE", "hex": "e5f6a7...64 bytes" }
  ]
}

Notes

Delegates to EvalSigBlock internally. All signature schemes supported via SCHEME field.
Public key is folded into the Merkle leaf via merkle_pub_key. The user supplies PUBKEY and the node incorporates it into the leaf hash automatically.
Wraps legacy P2PK semantics — no new data surfaces.
All signature schemes (Schnorr, ECDSA, PQ) supported via the SCHEME routing field.
Closes the arbitrary data surface present in raw P2PK outputs.

Use Cases

Legacy P2PK Migration

Wrap existing P2PK outputs in typed Ladder blocks. Same spending semantics with anti-spam protection.

Composable Key Spending

Combine with timelocks, hash locks, or covenants on other rungs. Legacy key-spending with full Ladder Script composability.

← ACCUMULATOR P2PKH_LEGACY →