How can a secure "Remember Me" function be implemented using cookies in PHP?

To implement a secure "Remember Me" function using cookies in PHP, you can generate a unique token for each user and store it in both a cookie and the database. When a user returns to the site, you can check if the token in the cookie matches the one in the database to authenticate the user. Additionally, make sure to hash the token and set secure and HttpOnly flags on the cookie for added security. 

// Generate a unique token
$token = bin2hex(random_bytes(16));

// Store the token in the user's cookie
setcookie('remember_token', $token, time() + 604800, '/', '', true, true);

// Store the hashed token in the database
$hashed_token = password_hash($token, PASSWORD_DEFAULT);
// Save $hashed_token in the database with the user's record

// Authenticate the user when they return
if(isset($_COOKIE['remember_token'])) {
    $token = $_COOKIE['remember_token'];
    // Retrieve the hashed token from the database for the user
    // Compare $token with the hashed token using password_verify()
    // If they match, authenticate the user
}

Keywords

PHP cookies remember me security implementation

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