How does a server manage and verify JWT tokens, especially in the context of API authentication?

To manage and verify JWT tokens in the context of API authentication, a server needs to validate the token's signature using a secret key, check the token's expiration date, and ensure that the token is issued by a trusted source. This process helps to authenticate users and authorize access to protected resources securely. 

<?php

use Firebase\JWT\JWT;

// JWT token verification
$jwt = $_SERVER['HTTP_AUTHORIZATION'];
$secret_key = "your_secret_key";

try {
    $decoded = JWT::decode($jwt, $secret_key, array('HS256'));
    
    // Token is valid, proceed with API request
    // Access user information from $decoded object
    
} catch (Exception $e) {
    // Token is invalid or expired
    http_response_code(401);
    echo json_encode(array("message" => "Unauthorized"));
}

Keywords

JWT token verification server-side authentication API PHP functions

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