Hi, today we will learn how to handle the error: “The edge runtime does not support Node.js crypto module.” I know this error might be a nightmare for some people. You will typically encounter this error when performing authentication or JWT token verification in middleware. If you are facing this issue, you can solve it with the help of a library called JOSE.

This error occurs in Next.js because it runs on the EDGE runtime. If you are not familiar with edge technology, here is an explanation:

What is Edge Runtime?

Edge runtime refers to running code closer to the end user, on servers distributed around the world rather than in a centralized location. This approach reduces latency, improves performance, and provides a better user experience. Next.js leverages this technology to enhance the speed and efficiency of web applications by processing requests at the edge of the network.

However, one limitation of the edge runtime is that it does not support certain Node.js modules, such as the crypto module, which is commonly used for tasks like JWT token verification. To handle JWT authentication in this environment, we can use alternative libraries like JOSE.

Using JOSE in Next.js

JOSE (JavaScript Object Signing and Encryption) is a library that provides tools for creating, signing, verifying, and decoding JWTs without relying on Node.js’ crypto module. Here’s how you can use JOSE in your Next.js project:

1. Install JOSE First, you need to install the JOSE library. Run the following command in your project directory:

   npm install jose

2. Create a Middleware for JWT Verification Next, create a middleware file, for example, middleware.js, where you will handle the JWT verification using JOSE.

   import { NextRequest } from 'next/server';
   import * as jose from 'jose';

   export const CheckAuthentication = async (token) => {
     const secret = new TextEncoder().encode(process.env.TOKEN_SECRET);
     try {
       const response = await jose.jwtVerify(token, secret);
       console.log(response.payload);
       return response.payload;
     } catch (error) {
       throw new Error("Your Token Expired");
     }
   };

3. Use Middleware in Your Application Create a middleware function to check authentication and protect your routes. For example, create a middleware.js file in your project:

   import { NextResponse } from 'next/server';
   import { CheckAuthentication } from './path/to/CheckAuthentication';

   export async function middleware(req) {
     const token = req.headers.get('Authorization')?.split(' ')[1];

     if (!token) {
       return new Response('Unauthorized', { status: 401 });
     }

     try {
       const user = await CheckAuthentication(token);
       req.user = user; // Attach user payload to the request
     } catch (err) {
       return new Response('Unauthorized', { status: 401 });
     }

     return NextResponse.next();
   }

4. Configure Middleware in Next.js Configure your Next.js application to use this middleware. You can define the middleware paths in your next.config.js:

   // next.config.js
   module.exports = {
     async middleware() {
       return [
         {
           source: '/api/:path*', // Adjust this according to your routes
           middleware: ['middleware.js'],
         },
       ];
     },
   };

5. Protect Your API Routes Now, any API route you want to protect with JWT authentication will go through this middleware. Make sure to adjust the paths in the middleware configuration to suit your application structure.

By understanding and adapting to the edge runtime, you can ensure your Next.js application runs smoothly and efficiently, even when performing complex tasks like authentication. Using the JOSE library allows you to handle JWTs without relying on the Node.js crypto module, making it a perfect fit for Next.js edge runtime environments.

Feel free to expand on these instructions with more detailed examples or additional context based on your specific use case.