How to Properly Implement OAuth 2.0 in a React App to Avoid Token Leakage?
I keep running into I'm currently implementing OAuth 2.0 in my React application using the `oidc-client` library (version 1.9.1). However, I'm concerned about potential token leakage issues, especially when dealing with redirects after authentication. I noticed that when the user is redirected back to my application, the access token is appended in the URL fragment, which could expose it to client-side scripts if not handled correctly. Here's a snippet of how I'm currently handling the login process: ```javascript import { UserManager } from 'oidc-client'; const config = { authority: 'https://your-identity-provider.com', client_id: 'your-client-id', redirect_uri: 'http://localhost:3000/callback', response_type: 'token', scope: 'openid profile api', }; const userManager = new UserManager(config); export const login = () => { userManager.signinRedirect(); }; export const handleCallback = async () => { const user = await userManager.signinRedirectCallback(); console.log('User: ', user); }; ``` After the redirect, I parse the URL to access the token, but I haven't found a secure way to do this without exposing it: ```javascript const handleRedirect = () => { const hash = window.location.hash; if (hash) { const token = hash.split('&')[0].split('=')[1]; // Extracting token directly // Secure storage? localStorage.setItem('access_token', token); window.location.hash = ''; // Clear hash to prevent leakage } }; ``` What best practices should I follow to ensure that I securely handle the access token and prevent any possible leakage? Should I consider using a state parameter, and how can I improve the security of the callback handling? Any advice would be greatly appreciated! The project is a mobile app built with Javascript. Any suggestions would be helpful. My development environment is macOS.