Server-side verification

When an end user connects their wallet, you, the developer, get a JSON Web Token (JWT) that can be used to verify some claims about the end user, notably a proof of ownership over a wallet public address.

Upon authentication, we generate a JWT signed with a private key (using RS256 algorithm) that is unique to you. In turn, you can use the associated public key (found in the API tab of your developer dashboard) to ensure that the token is authentic and hasn’t been tampered with. In other words, if a JWT issued by Dynamic can be successfully verified with your public key, the information it contains can be trusted.

You can do this in multiple ways.

Option 1: Leverage NextAuth

If you are using Next.js, you can easily integrate the NextAuth library with Dynamic to perform server-side verification and then use a session client-side.

Option 2: Leverage Passport.js

We offer an official passport-dynamic extension.

Option 3: Do-It-Yourself Verification

1. Get the JWT through the Dynamic SDK with an authToken.
2. Send the authToken to the server as a Bearer token

import { useEffect, useState } from "react";

export const useFetch = (authToken: string | null) => {
  const [data, setData] = useState({});

  useEffect(() => {
    const fetchApi = async () => {
      await fetch("http://localhost:9000/api", {
        headers: {
          Authorization: `Bearer ${authToken}`,
        },
      }).then(response => response.json()).then(setData);
    }

    fetchApi()
  }, [authToken]);

  return { data };
};

3. Install the node-jsonwebtoken and jwks-rsa packages
4. Validate the JWT on your server by fetching the public key from the JWKS endpoint API endpoint and verifying the encoded JWT against the public key:

import jwt, { JwtPayload } from 'jsonwebtoken';
import { JwksClient } from 'jwks-rsa';

// can be found in https://app.dynamic.xyz/dashboard/developer/api
const jwksUrl = `https://app.dynamic.xyz/api/v0/sdk/${YOUR_DYNAMIC_ENV_ID}/.well-known/jwks`

// The client should be initialized as
const client = new JwksClient({
  jwksUri: jwksUrl,
  rateLimit: true,
  cache: true,
  cacheMaxEntries: 5,  // Maximum number of cached keys
  cacheMaxAge: 600000 // Cache duration in milliseconds (10 minutes in this case))}
 });

const signingKey = await client.getSigningKey();
const publicKey = signingKey.getPublicKey();

const decodedToken: JwtPayload = jwt.verify(encodedJwt, publicKey, {
  ignoreExpiration: false,
}) as JwtPayload;

if (decodedToken.scopes.includes('requiresAdditionalAuth')) {
  // Either reject or handle the scopes appropriately.
  // `requiresAdditionalAuth` is the scope used to indicate that JWT requires additional verification such as MFA.
  throw new Error('Additional verification required');
}

console.log(decodedToken) // { iss: 'xxxx', exp: nnnn, ... }

This uses the following libraries:

• jwks-rsa: Provides client to interact and parse JWKS key signing data for a JWT.
• jsonwebtoken: Provides library to encode/decode and validate a JWT token.