PHP хэш-пароль для входа все время меняется

Привет, ребята, у меня есть некоторые проблемы с хэш-тегом для моего пароля: у меня проблема с логированием, потому что этот хэш всегда освежает..

И у меня еще один вопрос - это безопасный вход в систему?

Авторизоваться:

$email = htmlentities(addslashes($_POST['email']));
$password = create_hash($_POST['password']);
$ip_adresa = $_SERVER['REMOTE_ADDR'];

if(isset($_POST) && $email!='' && $password!=''){
    $test = mysql_fetch_array(mysql_query("SELECT * FROM users WHERE email='$email'"));
    $password = validate_password($password, $test['password']);

    $kveri = mysql_query("SELECT * FROM users WHERE email='$email' AND password='$password'");
    if (mysql_num_rows($kveri)) {
    $user = mysql_fetch_array($kveri);
    $_SESSION['userid'] = $user['userid'];
    $_SESSION['email'] = $user['email'];
    $mesec = 24*60*60*31; // mesec dana

    $sesija = md5($user['email'] . $cpass);

    if (isset($_POST['remember'])) {
        /* Set cookie to last 1 year */
        setcookie('email', $_POST['email'], time()+ $mesec);
        setcookie('password', md5($_POST['password']), time()+ $mesec);
    } else {
        /* Cookie expires when browser closes */
        setcookie('email', $_POST['email'], false);
        setcookie('password', md5($_POST['password']), false);
    }

    setcookie("userid", $user['userid'], time()+ $mesec);
    setcookie("email", $user['email'], time()+ $mesec);
    setcookie("sesija", $sesija, time() + $mesec);
    $_SESSION['ok'] = "Uspesno";
    mysql_query("UPDATE users SET ip='$ip_adresa',sesija='$sesija' WHERE userid='$_SESSION[userid]'");
    header("Location:/index.php");

    } else {
    $_SESSION['error'] = "Password or email are incorrect";
    header("Location:/index.php#sign-in");
    die();          
    }
} else {
    $_SESSION['error'] = "Email or password are empty";
    header("Location:/index.php#sign-in");
    die();
}

функции i, используемые для хеширования:

define("PBKDF2_HASH_ALGORITHM", "sha256");
define("PBKDF2_ITERATIONS", 1000);
define("PBKDF2_SALT_BYTE_SIZE", 24);
define("PBKDF2_HASH_BYTE_SIZE", 24);

define("HASH_SECTIONS", 4);
define("HASH_ALGORITHM_INDEX", 0);
define("HASH_ITERATION_INDEX", 1);
define("HASH_SALT_INDEX", 2);
define("HASH_PBKDF2_INDEX", 3);

function create_hash($password)
{
    // format: algorithm:iterations:salt:hash
    $salt = base64_encode(mcrypt_create_iv(PBKDF2_SALT_BYTE_SIZE, MCRYPT_DEV_URANDOM));
    return PBKDF2_HASH_ALGORITHM . ":" . PBKDF2_ITERATIONS . ":" .  $salt . ":" . 
        base64_encode(pbkdf2(
            PBKDF2_HASH_ALGORITHM,
            $password,
            $salt,
            PBKDF2_ITERATIONS,
            PBKDF2_HASH_BYTE_SIZE,
            true
        ));
}

function validate_password($password, $correct_hash)
{
    $params = explode(":", $correct_hash);
    if(count($params) < HASH_SECTIONS)
       return false; 
    $pbkdf2 = base64_decode($params[HASH_PBKDF2_INDEX]);
    return slow_equals(
        $pbkdf2,
        pbkdf2(
            $params[HASH_ALGORITHM_INDEX],
            $password,
            $params[HASH_SALT_INDEX],
            (int)$params[HASH_ITERATION_INDEX],
            strlen($pbkdf2),
            true
        )
    );
}

// Compares two strings $a and $b in length-constant time.
function slow_equals($a, $b)
{
    $diff = strlen($a) ^ strlen($b);
    for($i = 0; $i < strlen($a) && $i < strlen($b); $i++)
    {
        $diff |= ord($a[$i]) ^ ord($b[$i]);
    }
    return $diff === 0; 
}

/*
 * PBKDF2 key derivation function as defined by RSA PKCS #5: https://www.ietf.org/rfc/rfc2898.txt
 * $algorithm - The hash algorithm to use. Recommended: SHA256
 * $password - The password.
 * $salt - A salt that is unique to the password.
 * $count - Iteration count. Higher is better, but slower. Recommended: At least 1000.
 * $key_length - The length of the derived key in bytes.
 * $raw_output - If true, the key is returned in raw binary format. Hex encoded otherwise.
 * Returns: A $key_length-byte key derived from the password and salt.
 *
 * Test vectors can be found here: https://www.ietf.org/rfc/rfc6070.txt
 *
 * This implementation of PBKDF2 was originally created by https://defuse.ca
 * With improvements by http://www.variations-of-shadow.com
 */
function pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output = false)
{
    $algorithm = strtolower($algorithm);
    if(!in_array($algorithm, hash_algos(), true))
        trigger_error('PBKDF2 ERROR: Invalid hash algorithm.', E_USER_ERROR);
    if($count <= 0 || $key_length <= 0)
        trigger_error('PBKDF2 ERROR: Invalid parameters.', E_USER_ERROR);

    if (function_exists("hash_pbkdf2")) {
        // The output length is in NIBBLES (4-bits) if $raw_output is false!
        if (!$raw_output) {
            $key_length = $key_length * 2;
        }
        return hash_pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output);
    }

    $hash_length = strlen(hash($algorithm, "", true));
    $block_count = ceil($key_length / $hash_length);

    $output = "";
    for($i = 1; $i <= $block_count; $i++) {
        // $i encoded as 4 bytes, big endian.
        $last = $salt . pack("N", $i);
        // first iteration
        $last = $xorsum = hash_hmac($algorithm, $last, $password, true);
        // perform the other $count - 1 iterations
        for ($j = 1; $j < $count; $j++) {
            $xorsum ^= ($last = hash_hmac($algorithm, $last, $password, true));
        }
        $output .= $xorsum;
    }

    if($raw_output)
        return substr($output, 0, $key_length);
    else
        return bin2hex(substr($output, 0, $key_length));
}