TYPE 0x0902 · LEGACY FAMILY

P2PKH_LEGACY

Legacy P2PKH (pay-to-pubkey-hash) wrapped as a typed Ladder Script block. Verifies HASH160(pubkey) matches committed hash, then checks signature.

Legacy Non-Invertible

Ladder Diagram

Fields

Field	Data Type	Size	Side	Description
hash160	HASH160	20 B	Conditions	RIPEMD160(SHA256(pubkey)) commitment. Node-computed — the user provides PUBKEY and the node computes this field automatically. Raw hash input is rejected.
pubkey	PUBKEY	32-33 B	Witness	Public key — provided by the user. The node derives HASH160 from this key at creation time. Revealed at spend time.
signature	SIGNATURE	64-65 B	Witness	Signature over the transaction sighash

Wire Format Breakdown

Conditions side (committed in the rung leaf):

0x0902 0 1 HASH160 · 20B = 26 bytes

Witness side (in input witness):

0x0902 0 2 PUBKEY · 33B SIGNATURE · 64B = 105 bytes

Total (conditions + witness) 131 bytes

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

Evaluation Logic

1. Locate HASH160, PUBKEY, and SIGNATURE. Any missing → ERROR. HASH160 not exactly 20 B → ERROR

2. Compute CHash160(PUBKEY) = RIPEMD160(SHA256(PUBKEY)). memcmp against the committed HASH160; mismatch → UNSATISFIED

3. Read the optional conditions SCHEME (default Schnorr). Dispatch VerifySigWithScheme(pubkey, sig, scheme, ...) through the Ladder LadderSigChecker — not Core's BaseSignatureChecker, which would crash on a Schnorr sig outside Taproot context (regression fix `83f3a99a25`).

4. The VerifySigWithScheme result is the block result.

Return Values

Condition	Result
Missing HASH160, PUBKEY, or SIGNATURE	ERROR
HASH160 wrong size (not 20B)	ERROR
HASH160(PUBKEY) != committed hash	UNSATISFIED
Signature fails	UNSATISFIED
Signature valid	SATISFIED

JSON Wire Format

Conditions (committed in the rung leaf)

{
  "type": "P2PKH_LEGACY",
  "inverted": false,
  "fields": [
    { "type": "HASH160", "hex": "89abcd...20 bytes" }
  ]
}

Witness (input)

{
  "type": "P2PKH_LEGACY",
  "inverted": false,
  "fields": [
    { "type": "PUBKEY", "hex": "02abc1...33 bytes" },
    { "type": "SIGNATURE", "hex": "e5f6a7...64 bytes" }
  ]
}

Notes

Uses RIPEMD160(SHA256(pubkey)) like Bitcoin P2PKH.
The HASH160 field is node-computed: the user supplies PUBKEY and the node derives the hash commitment automatically. Submitting a raw HASH160 value directly is rejected.
Supports all signature schemes via optional SCHEME field.
The most common legacy Bitcoin output type, now wrapped with typed Ladder Script semantics.

Use Cases

Legacy P2PKH Migration

The most common Bitcoin output type. Wrap existing P2PKH in typed blocks.

Hash-Based Key Binding

HASH160 commitment hides the pubkey until spend time, same as original Bitcoin P2PKH.

← P2PK_LEGACY P2SH_LEGACY →