static void ValidateFingerprint (string fingerprint)
{
if (fingerprint == null)
throw new ArgumentNullException (nameof (fingerprint));
for (int i = 0; i < fingerprint.Length; i++) {
if (fingerprint[i] > 128 || !((byte) fingerprint[i]).IsXDigit ())
throw new ArgumentException ("The fingerprint should be a hex-encoded string.", nameof (fingerprint));
}
}