public int
recordLength() {
	return (name.length() + 10 +
		alg.length() +
		8 +	// time signed, fudge
		18 +	// 2 byte MAC length, 16 byte MAC
		4 +	// original id, error
		8);	// 2 byte error length, 6 byte max error field.
}
Returns the maximum length of a TSIG record generated by this key.
@see TSIGRecord
src/main/java/core/org/xbill/DNS/TSIG.java