public void keygen(String pubfile, String prvfile, String mskfile,
String attr_str) throws NoSuchAlgorithmException, IOException {
BswabePub pub;
BswabeMsk msk;
byte[] pub_byte, msk_byte, prv_byte;
pub_byte = Common.suckFile(pubfile);
pub = SerializeUtils.unserializeBswabePub(pub_byte);
msk_byte = Common.suckFile(mskfile);
msk = SerializeUtils.unserializeBswabeMsk(pub, msk_byte);
String[] attr_arr = LangPolicy.parseAttribute(attr_str);
BswabePrv prv = Bswabe.keygen(pub, msk, attr_arr);
prv_byte = SerializeUtils.serializeBswabePrv(prv);
Common.spitFile(prvfile, prv_byte);
}