Commitment Circuit

The commitment circuit (commitment.circom) handles the creation and verification of commitments:

template CommitmentHasher() {
    signal input value;              // Value being committed
    signal input label;              // keccak256(pool_scope, nonce)
    signal input nullifier;          // Unique nullifier
    signal input secret;             // Secret value

    signal output commitment;        // Final commitment hash
    signal output nullifierHash;     // Hashed nullifier
}

Key operations:

1. Nullifier hashing: nullifierHash = Poseidon([nullifier])
2. Precommitment: precommitmentHash = Poseidon([nullifier, secret])
3. Final commitment: commitment = Poseidon([value, label, precommitmentHash])