public static RRSIGRecord
sign(RRset rrset, DNSKEYRecord key, PrivateKey privkey,
     Date inception, Date expiration) throws DNSSECException
{
	return sign(rrset, key, privkey, inception, expiration, null);
}
Generate a DNSSEC signature.  key and privateKey must refer to the
same underlying cryptographic key.
@param rrset The data to be signed
@param key The DNSKEY record to use as part of signing
@param privkey The PrivateKey to use when signing
@param inception The time at which the signatures should become valid
@param expiration The time at which the signatures should expire
@throws UnsupportedAlgorithmException The algorithm is unknown
@throws MalformedKeyException The key is malformed
@throws DNSSECException Some other error occurred.
@return The generated signature
src/main/java/core/org/xbill/DNS/DNSSEC.java