ZKit - Circom Zero Knowledge Kit

A zero knowledge kit that helps you interact with Circom circuits.

• Generate and verify ZK proofs with a single line of code.
• Leverage groth16 and plonk proving systems.
• Render optimized Solidity | Vyper verifiers.
• Build and work with ZK witnesses.
• Substitute witness signals for advanced circuits testing.

Installation

To install the package, run:

npm install --save-dev @solarity/zkit

Usage

CircuitZKit

CircuitZKit is a user-friendly interface for interacting with circom circuits.

To create a CircuitZKit object it is necessary to pass a circuit config and a ProtocolImplementer instance:

const config = {
  circuitName: string;
  circuitArtifactsPath: string;
  verifierDirPath: string;
};

const implementer = new Groth16Implementer() | new PlonkImplementer();

const circuit = new CircuitZKit<"groth16" | "plonk">(config, implementer);

The config contains all the information required to work with the circuit, namely:

• circuitName - Name of the circuit file without extension.
• circuitArtifactsPath - Full path to compilation artifacts for the desired circuit.
• verifierDirPath - Full path to the directory where Solidity | Vyper verifier file will be generated.

The implementer is the instance of a certain proving system. Currently groth16 and plonk systems are supported.

API reference

---

• async createVerifier("sol" | "vy", verifierNameSuffix?: string)

Creates a Solidity | Vyper verifier contract with the optional verifierNameSuffix on verifierDirPath path, which was specified in the config.

await circuit.createVerifier("sol");
await circuit.createVerifier("sol", "_suffix_");

• async calculateWitness(inputs, witnessOverrides?) -> bigint[]

Calculates a witness in the tmp directory and returns its json representation. An optional witnessOverrides parameter can be provided to replace specific signal values in the generated witness file.

/// witness = [1n, 200n, 20n, 10n]
const witness = await circuit.calculateWitness({ a: 10, b: 20 });

/// witness = [1n, 200n, 35n, 10n]
const witness = await circuit.calculateWitness({ a: 10, b: 20 }, { "main.a": 35 });

• async generateProof(inputs, witnessOverrides?) -> proof

Generates a proof for the given inputs and witnessOverrides.

/// { proof: { pi_a, pi_b, pi_c, protocol, curve }, publicSignals: [6] }
const proof = await circuit.generateProof({ a: 2, b: 3 });

• async verifyProof(proof) -> bool

Verifies the proof.

/// true
const isValidProof = await circuit.verifyProof(proof);

• async generateCalldata(proof) -> calldata

Generates Calldata struct by proof for the Solidity | Vyper verifier's verifyProof() method.

/// You can use this `calldata` sturct in the circuit verifier contract.
/// calldata: { proofPoints: { a, b, c }, publicSignals: [6] }
const calldata = await circuit.generateCalldata(proof);

• getCircuitName() -> string

Returns the name of the circuit from the config.

• getVerifierName(verifierNameSuffix?: string) -> string

Returns the name of the verifier in the following form:

<Circuit name><Suffix><Proving system>Verifier

• getProvingSystemType() -> "groth16" | "plonk"

Returns the current proving system in use.

• getVerifierTemplate() -> string

Returns the full ejs verifier template as a string.