Keep Me Logged In - the best approach

suggest change

store the cookie with three parts.

function onLogin($user) {
    $token = GenerateRandomToken(); // generate a token, should be 128 - 256 bit
    storeTokenForUser($user, $token);
    $cookie = $user . ':' . $token;
    $mac = hash_hmac('sha256', $cookie, SECRET_KEY);
    $cookie .= ':' . $mac;
    setcookie('rememberme', $cookie);
}

Then, to validate:

function rememberMe() {
    $cookie = isset($_COOKIE['rememberme']) ? $_COOKIE['rememberme'] : '';
    if ($cookie) {
        list ($user, $token, $mac) = explode(':', $cookie);
        if (!hash_equals(hash_hmac('sha256', $user . ':' . $token, SECRET_KEY), $mac)) {
            return false;
        }
        $usertoken = fetchTokenByUserName($user);
        if (hash_equals($usertoken, $token)) {
            logUserIn($user);
        }
    }
}

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* Keep Me Logged In - the best approach

Table Of Contents
2 Arrays
4 Types
10 Cookies
14 JSON
15 SOAP
17 cURL
19 XML
21 Traits
35 UTF-8
36 URLs
38 PHPDoc
41 Loops
44 Closur
72 YAML
77 Cache
78 Streams
81 PDO
82 SQLite3
83 Sockets
87 MongoDB
93 IMAP
94 Redis
95 Imagick
102 APCu
104 Secure remember me
108 PSR