Contracts

Beacon’s on-chain surface is two small contracts plus one verifier per catalog circuit. Consumers only ever call VerifierHub.verify.

VerifierHub

The stateless, trustless verification entrypoint. It looks a circuit up in the registry, checks the public-input count, and routes to the registered verifier via STATICCALL.

interface IVerifierHub {
    function verify(bytes32 circuitId, bytes calldata proof, bytes32[] calldata publicInputs)
        external
        view
        returns (bool);
}

• view — verification is a pure cryptographic check, so it costs no state and can’t be forged.
• Stateless — the hub holds no app state. Replay protection (spent nullifiers) is your contract’s responsibility.
• Reverts on an unknown or inactive circuitId, or a wrong public-input count; returns false only when the proof itself is invalid.

CircuitRegistry

The owner-curated catalog. Maps an immutable, content-addressed circuitId to its verifier and metadata.

circuitId = keccak256(abi.encode(name, version));

Each entry stores { verifier, vkHash, publicInputs, active, schema }. Entries are immutable once registered — only the active flag can be toggled. A new circuit version is a new circuitId and a new verifier, so a pinned id never changes meaning.

Governance: the registry is single-owner today (it can add and (de)activate entries). Ownership moves to a multisig before mainnet.

The membership circuit

v1 ships a single predicate: prove membership in a Merkle set without revealing which member, with a scope-bound nullifier for replay protection.

Public-input convention

publicInputs = [scope, root, nullifier]

• scope — a bytes32 domain separator you choose (e.g. a proposal id, an epoch, an app id). It binds the proof and nullifier to a context. It must be a canonical BN254 field element; the SDK reduces your value and returns the exact publicInputs to pass on-chain.
• root — the Merkle root of the membership set.
• nullifier — a one-time marker, unique per (scope, member), that lets you reject replays without linking back to the member.

Protocol facts (SDK and contract agree)

leaf       = Poseidon2(secret)
nullifier  = Poseidon2(scope mod p, secret)

These are fixed by the deployed verification key. If you generate proofs, use @privacy-protocol/beacon at the pinned peer-dependency versions so your proofs match the on-chain verifier.

Next steps

• Integrate — make your contract a consumer
• Deployments — live addresses