mirror of
https://github.com/tornadocash/snarkjs.git
synced 2024-10-31 23:35:40 +01:00
129 lines
3.7 KiB
Markdown
129 lines
3.7 KiB
Markdown
# snarkjs: JavaScript implementation of zkSNARKs.
|
|
|
|
This is a JavaScript implementation of zkSNARK schemes.
|
|
|
|
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.
|
|
|
|
```sh
|
|
npm install snarkjs
|
|
```
|
|
|
|
## Usage from command line.
|
|
|
|
|
|
```sh
|
|
snarkjs --help
|
|
```
|
|
|
|
Will show all the info in how to use the cli.
|
|
|
|
## Ussage from jacascript
|
|
|
|
|
|
### Import.
|
|
|
|
```js
|
|
const zkSnark = require("snarkjs");
|
|
```
|
|
|
|
### Load a circuit.
|
|
|
|
```js
|
|
// "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.
|
|
|
|
```js
|
|
// `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.
|
|
|
|
```js
|
|
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.
|
|
|
|
```js
|
|
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.
|
|
|
|
```js
|
|
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.
|
|
|
|
|