/**
* Generate token basing on field names and custom key
*
* @param string|null $salt Encryption salt
*
* @return string
* @throws \InvalidArgumentException
*/
public function tokenize($salt = null)
{
if ($salt === null) {
$salt = $this->encrypter->randSalt();
}
$value = implode('', array_keys($this->fields));
$token = $this->encrypter->crypt($value, $salt);
return $token;
}
