public function unsetPassphrase($signkey = false)
{
global $session;
if ($signkey) {
$session->remove('imp', 'smime_null_passphrase_sign');
$session->remove('imp', 'smime_passphrase_sign');
} else {
$session->remove('imp', 'smime_null_passphrase');
$session->remove('imp', 'smime_passphrase');
}
}