hmac.update(old.getSignature());
}
m.getHeader().decCount(Section.ADDITIONAL);
byte [] header = m.getHeader().toWire();
m.getHeader().incCount(Section.ADDITIONAL);
hmac.update(header);
int len = m.tsigstart - header.length;
hmac.update(b, header.length, len);
DNSOutput out = new DNSOutput();