fhevm-solidity/docs/frontend/node.md

Build with Node

This document provides instructions on how to build with Node.js using the @fhevm/sdk library.

Install the library

First, you need to install the library:

# Using npm
npm install @fhevm/sdk

# Using Yarn
yarn add @fhevm/sdk

# Using pnpm
pnpm add @fhevm/sdk

@fhevm/sdk 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 @fhevm/sdk. If your node project use "type": "module", you can force the loading of the Node version by using import { createInstance } from '@fhevm/sdk/node';

Create an instance

An instance receives an object containing:

• chainId (optional): the chainId of the network
• network (optional): the Eip1193 object provided by window.ethereum (used to fetch the public key and/or chain id)
• networkUrl (optional): the URL of the network (used to fetch the public key and/or chain id)
• publicKey (optional): if the public key has been fetched separately (cache), you can provide it
• gatewayUrl (optional): the URL of the gateway to retrieve a reencryption
• coprocessorUrl (optional): the URL of the coprocessor

const { createInstance } = require("@fhevm/sdk");

const createFhevmInstance = async () => {
  return createInstance({
    chainId: 11155111, // Sepolia chain ID
    networkUrl: "https://eth-sepolia.public.blastapi.io", // Sepolia RPC URL
    gatewayUrl: "https://gateway.sepolia.zama.ai",
  });
};
createFhevmInstance().then((instance) => {
  console.log(instance);
});

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