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Create JWT using jsonwebtoken package

For your custom JWT provider, you can create JWT token using package of your choice, one of which is jsonwebtoken package. Learn more about jsonwebtoken.

Installation​

$ npm i jsonwebtoken

Generate Private key​

Paste the below command in terminal to generate a new file privateKey.pem with the key details. The generated key will be used to sign the token.

openssl genrsa -out privateKey.pem 2048

Once you have generated private key, you can get the public key which can be used to verify the JWT.

openssl rsa -in privateKey.pem -pubout -out publicKey.pem

Generate JWT​

For jsonwebtoken we have documented RSA256 and ECDSA, two of the most popular algorithms used to generate the JWT. For the list of supported algorithms by jsonwebtoken, you can checkout their documentation.

Using RSA for JWT Signing​

Create an index.js file and paste the below code to generate the JWT using RSA algorithm.

import jwt from "jsonwebtoken";
import fs from "fs";

var privateKey = fs.readFileSync("privateKey.pem");

var token = jwt.sign(
  {
    sub: "faj2720i2fdG7NsqznOKrthDvq43", // must be unique to each user
    name: "Mohammad Shahbaz Alam",
    email: "shahbaz@web3auth.io",
    aud: "urn:my-resource-server", // -> to be used in Custom Authentication as JWT Field
    iss: "https://my-authz-server", // -> to be used in Custom Authentication as JWT Field
    iat: Math.floor(Date.now() / 1000),
    exp: Math.floor(Date.now() / 1000) + 60 * 60,
  },
  privateKey,
  { algorithm: "RS256", keyid: "1bb9605c36e69386830202b2d" }, // <-- Replace it with your kid. This has to be present in the JWKS endpoint.
);

console.log(token);

Create JWKS​

Once you have created the script to sign the JWT, it's time to convert publicKey.pem file to jwk(s) format. One of the tool you can use to convert is https://pem2jwk.vercel.app/.

  • Select the correct signing algorithm: RS256
  • Select Public Key use: Signing
  • Key ID: paste-your or leave it blank to generate a random one.
  • PEM encoded key: {paste-the-publicKey-pem-file-s-content-here}
  • Click on the Convert to JWK button.

JWKS Convert Tool

To complete the process, you need to save the output as a .json file, host it on your server, and make sure it's publicly accessible. This will give you the JWKS Endpoint, which is required when setting up a Custom JWT Verifier on the Web3Auth Dashboard.