#2 SSO

🔐 Advanced SSO using OAuth 2.0 with PHP

📘 What is OAuth 2.0?

OAuth 2.0 is a secure authorization framework that allows users to login using external providers like Google without sharing passwords.

⚙️ OAuth Flow

User → Redirect to Provider → Login → Authorization Code → Token → User Info → Login

📦 Install Google Client Library

composer require google/apiclient

🔑 Step 1: Create OAuth Client

• Go to Google Cloud Console
• Create project
• Enable OAuth
• Get Client ID & Secret

💻 Step 2: Login Redirect Code

<?php
require 'vendor/autoload.php';
$client = new Google_Client();
$client->setClientId('YOUR_CLIENT_ID');
$client->setClientSecret('YOUR_CLIENT_SECRET');
$client->setRedirectUri('http://localhost/callback.php');
$client->addScope("email");
$client->addScope("profile");

echo "<a href='".$client->createAuthUrl()."'>Login with Google</a>";

🔄 Step 3: Callback Handling

<?php
require 'vendor/autoload.php';
$client = new Google_Client();
$client->setClientId('YOUR_CLIENT_ID');
$client->setClientSecret('YOUR_CLIENT_SECRET');
$client->setRedirectUri('http://localhost/callback.php');

$token = $client->fetchAccessTokenWithAuthCode($_GET['code']);
$client->setAccessToken($token);

$oauth = new Google_Service_Oauth2($client);
$user = $oauth->userinfo->get();

echo "Welcome ".$user->email;

🔗 Step 4: WordPress Integration

After login, pass user email to WordPress and auto-login using custom plugin.

🔒 Security Features

• Token-based authentication
• No password sharing
• Secure redirect
• Access control via scopes

🎓 MCQs

• OAuth is used for authorization
• Access token is temporary
• Client ID identifies application