#0 SSO

🔐 Single Sign-On (SSO) using PHP

📘 What is SSO?

Single Sign-On (SSO) allows users to login once and access multiple systems without logging again.

⚙️ How SSO Works

• User logs into main system
• JWT token is generated
• User redirected to another system
• Token verified
• User logged in automatically

📦 Install JWT Library

composer require firebase/php-jwt

🔑 Token Generation Code

<?php
use Firebase\JWT\JWT;
$payload = [
 "email" => "user@gmail.com",
 "iat" => time(),
 "exp" => time()+300
];
$jwt = JWT::encode($payload, "secret", 'HS256');
header("Location: app2.php?token=".$jwt);
exit;

✅ Token Verification Code

<?php
use Firebase\JWT\JWT;
use Firebase\JWT\Key;
$decoded = JWT::decode($_GET['token'], new Key("secret", 'HS256'));
echo "Welcome ".$decoded->email;

🔄 Flow

Login → Token → Redirect → Verify → Access

🔒 Security Tips

• Use HTTPS
• Short token expiry
• Keep secret key safe

🎓 MCQs

• JWT stands for JSON Web Token
• SSO means single login multiple access
• Token expiry improves security