private static void
digestSIG(DNSOutput out, SIGBase sig) {
	out.writeU16(sig.getTypeCovered());
	out.writeU8(sig.getAlgorithm());
	out.writeU8(sig.getLabels());
	out.writeU32(sig.getOrigTTL());
	out.writeU32(sig.getExpire().getTime() / 1000);
	out.writeU32(sig.getTimeSigned().getTime() / 1000);
	out.writeU16(sig.getFootprint());
	sig.getSigner().toWireCanonical(out);
}
Converts a textual representation of an algorithm into its numeric
code.  Integers in the range 0..255 are also accepted.
@param s The textual representation of the algorithm
@return The algorithm code, or -1 on error.
src/main/java/core/org/xbill/DNS/DNSSEC.java