Build with Node

First, you need to install the library.

# Using npm
npm install fhevmjs

# Using Yarn
yarn add fhevmjs

# Using pnpm
pnpm add fhevmjs

fhevmjs uses ESM format for web version and commonjs for node version. You need to set the type to "commonjs" in your package.json to load the correct version of fhevmjs. If your node project use "type": "module", you can force the loading of the Node version by using import { createInstance } from 'fhevmjs/node';

Create an instance

const { createInstance, getPublicKeyCallParams } = require("fhevmjs");
const { ethers, JsonRpcProvider } = require("ethers");

const provider = new JsonRpcProvider(``);

const createFhevmInstance = async () => {
  // 1. Get the chain id
  const network = await provider.getNetwork();
  const chainId = +network.chainId.toString();
  // 2. Fetch the FHE public key from the blockchain
  const ret = await;
  const decoded = ethers.AbiCoder.defaultAbiCoder().decode(["bytes"], ret);
  const publicKey = decoded[0];

  // 3. Create the instance
  return createInstance({ chainId, publicKey });
createFhevmInstance().then((instance) => {

You can now use your instance to encrypt parameters or do a reencryption.

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