{
if ( priv == null )
{
throw new ValidationException ("Need private key to sign");
}
ECDSASigner signer = new ECDSASigner (new HMacDSAKCalculator (new SHA256Digest ()));
signer.init (true, new ECPrivateKeyParameters (priv, domain));
BigInteger[] signature = signer.generateSignature (hash);
ByteArrayOutputStream s = new ByteArrayOutputStream ();
try
{