Welcome to the documentation for fhevmjs, a JavaScript library that enables interaction with blockchain using Zama's technology! This comprehensive guide provides developers with detailed information on encryption of data using TFHE (Fully Homomorphic Encryption over the Torus) and generation of EIP-719 tokens for reencrypt data.

Installation

To get started with fhevmjs, you need to install it as a dependency in your JavaScript project. You can do this using npm, Yarn or pnpm. Open your terminal and navigate to your project's directory, then run one of the following commands:

# Using npm
npm install fhevmjs

# Using Yarn
yarn add fhevmjs

# Using pnpm
pnpm add fhevmjs

This will download and install the fhevmjs library and its dependencies into your project.

To use the library in your project, you need to load WASM of TFHE first with initFhevm.

import { BrowserProvider } from "ethers";
import { initFhevm, createInstance } from "fhevmjs";

const createFhevmInstance = async () => {
  const provider = new BrowserProvider(window.ethereum);
  const network = await provider.getNetwork();
  const chainId = +network.chainId.toString();
  const publicKey = await provider.call({
    from: null,
    to: "0x0000000000000000000000000000000000000044",
  });
  return createInstance({ chainId, publicKey });
};

const init = async () => {
  await initFhevm(); // Load TFHE
  return createFhevmInstance();
};

init().then((instance) => {
  console.log(instance);
});

Troubleshooting

Webpack: "Module not found: Error: Can't resolve 'tfhe_bg.wasm'"

In the codebase, there is a new URL('tfhe_bg.wasm') which triggers a resolve by Webpack. If yo u encounter an issue, you can add a fallback for this file by adding a resolve configuration in y our webpack.config.js:

    resolve: {
      fallback: {
        'tfhe_bg.wasm': require.resolve('tfhe/tfhe_bg.wasm'),
      },
    },

Issue with importing ESM version

With a bundler such as Webpack or Rollup, imports will be replaced with the version mentioned in the "browser" field of the package.json. If you encounter issue with typing, you can use this tsconfig.json using TypeScript 5.

If you encounter any other issue, you can force import of the browser package.

import { initFhevm, createInstance } from "fhevmjs/web";

Use bundled version

If you have an issue with bundling the library (for example with some SSR framework), you can use the prebundled version available in fhevmjs/bundle. Just embed the library with a <script> tag and you're good to go.

const start = async () => {
  await window.fhevm.initFhevm(); // load wasm needed
  const instance = window.fhevm.createInstance({ chainId, publicKey }).then((instance) => {
    console.log(instance);
  });
};

React

You can use this template to start an application with fhevmjs, using Vite + React + Typescript.

fhevmjs include a Command-Line Interface (CLI) tool. With this handy utility, you can encrypt 8/16/32bits integer with the blockchain's FHE public key. To get started with fhevmjs CLI, first, ensure you have Node.js installed on your system. Next, install the fhevmjs package globally using the '-g' flag, which allows you to access the CLI tool from any directory:

Once installed, fhevm command should be available. You can get all commands and options available with fhevm help or fhevm encrypt help.

Examples

Encrypt 71721075 as 32bits integer: