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zkSNARK implementation in JavaScript
src | ||
templates | ||
test | ||
.eslintrc.js | ||
.gitignore | ||
cli.js | ||
COPYING | ||
index.js | ||
package-lock.json | ||
package.json | ||
README.md | ||
vk_proof.json | ||
vk_verifier.json |
snarkjs: JavaScript implementation of zkSNARKs.
This is a JavaScript implementation of zkSNARK schemes. It allows the original 8points protocol and the Groth Protocol (3 point only and 3 pairings)
This library allows to do the trusted setup, generate proofs and verify the proofs.
This library uses the compiled circuits generated by the jaz compiler.
Install.
npm install snarkjs
Usage from command line.
snarkjs --help
Will show all the info in how to use the cli.
Ussage from jacascript
Import.
const zkSnark = require("snarkjs");
Load a circuit.
// "myCircuit.cir" is the output of the jaz compiler
const circuitDef = JSON.parse(fs.readFileSync("myCircuit.cir", "utf8"));
const circuit = new zkSnark.Circuit(circuitDef);
Inspect the circuit.
// `signalId` can always be a number or an alias string
circuit.nConstraints; // number of constraints
circuit.nSignals; // number of signals
circuit.nPublic; // number of public signals (nOutputs + nPublicInputs)
// The array of signals is always sorted in this order:
// [ 1, outputs, publicInputs, privateInputs, internalSignals, constants]
// returns a,b and c coeficients of the `signalId` on a given `constraint`
circuit.a(constraint, signalId)
circuit.b(constraint, signalId)
circuit.c(constraint, signalId)
circuit.nOutputs // number of public outputs
circuit.pubInputs // number of public inputs
circuit.nPrvInputs // number of private inputs
circuit.nInputs // number of inputs ( nPublicInputs + nPrivateInputs)
circuit.nVars // number of variables ( not including constants (one is a variable) )
circuit.nSignals // number of signals ( including constants )
circuit.outputIdx(i) // returns the index of the i'th output
circuit.inputIdx(i) // returns the index of the i'th input
circuit.pubInputIdx(i) // returns the index of the i'th public input
circuit.prvInputIdx(i) // returns the index of the i'th private input
circuit.varIdx(i) // returns the index of the i'th variable
circuit.constantIdx(i) // returns the index of the i'th constant
circuit.signalIdx(i) // returns the index of the i'th signal
// returns signal Idx given a signalId
// if the idx >= n , it is a constant
// if the idx == -1, the signal does not exist
circuit.getSignalIdx(name);
// returns an array aliases names of the i'th signal
circuit.signalNames(i)
// input is a key value object where keys are the signal names
// of all the inputs (public and private)
// returns an array of values representing the witness
circuit.calculateWitness(input)
Trusted setup.
const setup = zkSnark.setup(circuit);
fs.writeFileSync("myCircuit.vk_proof", JSON.stringify(setup.vk_proof), "utf8");
fs.writeFileSync("myCircuit.vk_verifier", JSON.stringify(setup.vk_verifier), "utf8");
setup.toxic // Must be discarded.
Generate proof.
const circuitDef = JSON.parse(fs.readFileSync("myCircuit.cir", "utf8"));
const circuit = new zkSnark.Circuit(circuitDef);
const input = {
"main.pubIn1": "123",
"main.out1": "456"
}
const witness = circuit.calculateWitness(input);
const vk_proof = JSON.parse(fs.readFileSync("myCircuit.vk_proof", "utf8"));
const {proof, publicSignals} = zkSnark.genProof(vk_proof, witness);
Verifier.
const vk_verifier = JSON.parse(fs.readFileSync("myCircuit.vk_verifier", "utf8"));
if (zkSnark.isValid(vk_verifier, proof, publicSignals)) {
console.log("The proof is valid");
} else {
console.log("The proof is not valid");
}
License
snarkjs is part of the iden3 project copyright 2018 0KIMS association and published with GPL-3 license. Please check the COPYING file for more details.