Witness CirclesWITC protocol

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    WITC . Original Bitcoin Universe protocol

    Membership you can derive from the chain.

    Witness Circles records a group by mutual witnessing. Two to sixteen independent Taproot output keys sign one exact Bitcoin transaction. The group exists because the commitments close the loop, and its state is derived from what those keys published, never from a server.

    Read the specification Open the circle simulator
    • Bitcoin, Taproot key path
    • Specification 1.0.0
    • Experimental
    • No token, no market
    Six member nodes on a closed luminous ring around a WITC marker Concentric rings surround a central marker labelled WITC. Six nodes sit on the inner ring, each joined to the marker by a luminous spoke, and the ring between them is unbroken. WITC CIRCLE

    How a circle closes

    Most membership systems record a claim and hope you trust the recorder. Witness Circles has no recorder. Each participant contributes one confirmed, dedicated Taproot input to a single transaction, and each participant gets their coin back to the same key minus an equal share of the miner fee. Nothing is transferred. The only thing produced is proof that these exact keys agreed to this exact transaction.

    A circle forming in three stages Stage one shows three separate key nodes with no connections and an empty marker in the middle. Stage two shows two of the three keys joined by luminous attestation arcs while the third stays muted, leaving a visible gap in the ring. Stage three shows all three keys joined, the ring unbroken, and the WITC marker committed at the centre. Only stage three is a valid Circle. no marker 1. Three independent keys Nothing is committed. There is no circle. WITC pending 2. Two commitments, one missing The loop is open, so no state changes. WITC 0x01 3. The loop closes One transaction, one marker, three shards.
    Membership is derived, not declared. A Circle exists only when every participant signs the same transaction, so the ring either closes completely or the record does not exist at all. There is no partial membership and no pending state on chain.

    What a Circle proves, and what it does not

    It proves

    Distinct native P2TR output keys authorized one exact Bitcoin transaction under Taproot key-path signature rules, at a position in the best chain, committing to a shared context hash.

    It does not prove

    Human identity or personhood. Attendance or physical presence. Friendship, endorsement or legal agreement. One key per person. Ownership before or after any period not established by the indexed UTXO history.

    Do not use a Circle as proof of a person. Keys can be shared, automated, rented or held by one party using sixteen wallets. The claim boundary in section 1 of the specification is normative, and a compliant application must not present a Circle as more than it is.

    The protocol in six numbers

    2 to 16independent output keys per Circle
    42 bytesexact marker script, 6a28 plus a 40 byte payload
    1,000 satsminimum successor output per member
    246 + 402Nweight units for 64 byte signatures
    1confirmation before a Circle is authoritative
    0tokens, balances, transfers or markets

    State is derived, never declared

    A Circle transaction creates one shard for each participant: the successor output that carries the same script as their input. The chain of shards that starts at a participant's first Circle is a lineage, identified by hashing its genesis outpoint. A later Circle that spends an active shard continues that lineage and records a continuation edge. Any other confirmed spend of an active shard closes the lineage for good.

    Lineages advancing through two Circles and one closure Three lineages are created by the genesis Circle at height 200. Two of them continue into a second Circle at height 201, which the indexer records as continuation edges. At height 202 an ordinary Bitcoin spend consumes one active shard, which closes that lineage permanently. The third lineage never continues and stays active. height 200 height 201 height 202 circle 3703…0f65 circle f7c7…28ef ordinary spend lineage 4bc0… continues lineage 63c2… continues lineage ee74… stays active, never continued shard spent outside the protocol Closure is a property of the UTXO set, not of parser opinion.
    The lifecycle committed in test-vectors/v1/state-lifecycle.json: one genesis Circle, one continuation, and one ordinary spend that closes a lineage. A consensus-valid transaction that spends an active shard without satisfying every Circle rule closes that lineage. No Bitcoin is burned, and the historical Circles remain in the best-chain record.

    Every indexer that follows the specification derives the same snapshot and therefore the same state hash. The empty state hashes to 90e749b7720fac379610d979e29998c7d650150548622f0a47d9d3e181f1be52, and the published lifecycle vector pins the hash after each transition and after each rollback.

    Who this is for

    Protocol implementers

    Write a second implementation. The specification is normative, the test vectors are binding, and conformance tells you exactly what must agree.

    Indexer operators

    Confirmation, mempool and reorganization behaviour are specified, not left to taste. See the indexer semantics.

    Wallet and application developers

    Section 13 lists what a wallet must verify before signing. The guide walks a real transaction byte by byte.

    Where this stands today

    Verified against this repository at commit 6507df3848c9.
    QuestionAnswer
    LifecycleExperimental. The reference implementation is published for parser interoperability, wallet safety review and testing.
    ChainBitcoin.
    NetworksCircle planning and marker creation fail closed outside Signet and regtest. Mainnet and testnet3 identifiers are defined and parseable for read-only interoperability.
    Specification version1.0.0, operation CIRCLE (0x01), protocol version byte 0x01.
    Reference package@bitcoinuniverse/witness-circles 0.1.0, MIT. No reviewed registry release exists yet, so install from a verified checkout.
    Marketplace supportNone. Witness Circles has no entry in the Bitcoin Universe marketplace protocol registry, so no Universe product implements a trade path for it. There is nothing to trade: the protocol defines no transferable asset.
    Wallet supportNo wallet integration is verified in Bitcoin Universe code today. The requirements a wallet must meet are specified in section 13.
    IndexingIndexed by its own indexer implementation, index-witness-circles, alongside the reference state engine in this repository.

    Entry points

    Source

    bitcoinuniverseio/witness-circles holds the specification, reference implementation, schemas and vectors.

    Portal

    This component is listed on the Bitcoin Universe documentation portal at docs.bitcoinuniverse.io/protocols/witness-circles.

    Security

    Report vulnerabilities privately through GitHub private vulnerability reporting. Do not open a public issue for an unpatched fund-loss finding.