if err != nil {
		return nil, err
	}
	return x509.ParseCertificate(certDERBytes)
}

// RemoveDuplicateAltNames removes duplicate items in altNames.
func RemoveDuplicateAltNames(altNames *certutil.AltNames) {
	if altNames == nil {
		return
	}

	if altNames.DNSNames != nil {
		altNames.DNSNames = sets.List(sets.New(altNames.DNSNames...))
	}