protected static function _fromASN1Params(UnspecifiedType $params = null)
{
if (!isset($params)) {
throw new \UnexpectedValueException("No parameters.");
}
$key_bits = 32;
// rfc2268 a choice containing only IV
if ($params->isType(Element::TYPE_OCTET_STRING)) {
$iv = $params->asOctetString()->string();
} else {
$seq = $params->asSequence();
$idx = 0;
// version is optional in rfc2898
if ($seq->has($idx, Element::TYPE_INTEGER)) {
$version = $seq->at($idx++)->asInteger()->number();
$key_bits = self::_versionToEKB($version);
}
// IV is present in all variants
$iv = $seq->at($idx)->asOctetString()->string();
}
return new self($key_bits, $iv);
}
