TYPE 0x0504 · ANCHOR FAMILY

ANCHOR_RESERVE

Reserve and federation anchor. Verifies an N-of-M threshold guardian set with a committed guardian set hash. Used to anchor federated sidechain parameters and multi-guardian reserve configurations.

Anchor Invertible

Ladder Diagram

Fields

Field	Data Type	Size	Side	Description
threshold_n	NUMERIC	1-4 B	Conditions	Required number of guardian signatures. Must be `≥ 0` and `≤ threshold_m`.
threshold_m	NUMERIC	1-4 B	Conditions	Total number of guardians. Must be `≥ 0`.
guardian_set_hash	HASH256	32 B	Conditions	Hash committing to the full guardian pubkey set. Must equal `SHA256(witness PREIMAGE)` at spend time (hash binding via VerifyHashPreimageBinding).
preimage	PREIMAGE	var	Witness	Preimage whose SHA-256 must equal `guardian_set_hash`. Required at spend time; in practice this is a deterministic serialisation of the guardian pubkey set.

Wire Format Breakdown

0x0504 0 3 NUMERIC · 3B NUMERIC · 3B HASH256 · 32B Conditions = 48 bytes

0x0504 0 1 PREIMAGE · var Witness ≈ 4 + 1 + len bytes

Total ≈ 53 + len bytes

Evaluation Logic

1.Collect NUMERIC fields. Fewer than 2, or no HASH256 present (HasRequiredHashes(block, 1)) → ERROR

2.VerifyHashPreimageBinding(block): each conditions HASH256 must match SHA256 of a corresponding witness PREIMAGE (in field order). Missing PREIMAGE, undersized HASH256, or mismatch → UNSATISFIED

3.ReadNumeric on the first two NUMERICs: threshold_n and threshold_m. Either undecodable → UNSATISFIED

4.Range/order check: threshold_n < 0, threshold_m < 0, or threshold_n > threshold_m → UNSATISFIED

5.All checks passed → SATISFIED

Return Values

Condition	Result
Fewer than 2 NUMERIC fields, or HASH256 absent	ERROR
Witness has no PREIMAGE, or hash binding fails	UNSATISFIED
HASH256 not exactly 32 B	UNSATISFIED
Either NUMERIC undecodable	UNSATISFIED
`threshold_n < 0`, `threshold_m < 0`, or `threshold_n > threshold_m`	UNSATISFIED
Hash binding holds, `0 ≤ n ≤ m`	SATISFIED

JSON Wire Format

Conditions (3-of-5 guardian reserve — committed in the rung leaf)

{
  "type": "ANCHOR_RESERVE",
  "inverted": false,
  "fields": [
    { "type": "NUMERIC", "value": 3 },
    { "type": "NUMERIC", "value": 5 },
    { "type": "HASH256", "hex": "c7d8e9f0...guardian set hash...32 bytes" }
  ]
}

Witness (input)

{
  "type": "ANCHOR_RESERVE",
  "fields": [
    { "type": "PREIMAGE", "hex": "... preimage that hashes to guardian_set_hash ..." }
  ]
}

Anchors a 3-of-5 threshold guardian set. The hash commits to the ordered list of all 5 guardian pubkeys; the spend reveals a preimage equal to the canonical serialisation of that list.

Use Cases

Federated Sidechain Anchors

Anchor the federation parameters of a sidechain on the main chain. The threshold and guardian set hash define who controls the peg, providing an auditable on-chain record of the federation configuration.

Multi-guardian Reserves

Commit reserve custody parameters on-chain. An N-of-M guardian set controls the reserve, with the hash binding to the specific guardian pubkeys. Enables transparent proof-of-reserves with verifiable custody thresholds.

← ANCHOR_POOL ANCHOR_SEAL →