2 import java.util.Vector;
3 import java.nio.ByteBuffer;
4 import javax.crypto.Mac;
5 import java.util.Arrays;
8 public static final int SLOT_SIZE=2048;
9 public static final int HMAC_SIZE=32;
15 Vector<Entry> entries;
17 Slot(long _seqnum, long _machineid, byte[] _prevhmac, byte[] _hmac, Vector<Entry> _entries) {
25 Slot(long _seqnum, byte[] _bytes) {
33 byte[] getPrevHMAC() {
37 static Slot decode(byte[] array, Mac mac) {
38 mac.update(array, HMAC_SIZE, array.length-HMAC_SIZE);
39 byte[] realmac=mac.doFinal();
41 ByteBuffer bb=ByteBuffer.wrap(array);
42 byte[] hmac=new byte[HMAC_SIZE];
43 byte[] prevhmac=new byte[HMAC_SIZE];
46 if (!Arrays.equals(realmac, hmac))
47 throw new Error("Invalid HMAC! Potential Attack!");
49 long seqnum=bb.getLong();
50 long machineid=bb.getLong();
51 int numentries=bb.getInt();
52 Vector<Entry> entries=new Vector<Entry>();
53 for(int i=0;i<numentries;i++) {
54 entries.add(Entry.decode(bb));
57 return new Slot(seqnum, machineid, prevhmac, hmac, entries);
60 byte[] encode(Mac mac) {
61 byte[] array=new byte[SLOT_SIZE];
62 ByteBuffer bb=ByteBuffer.wrap(array);
63 bb.position(HMAC_SIZE); //Leave space for the HMACs
66 bb.putLong(machineid);
67 bb.putInt(entries.size());
68 for(Entry entry:entries) {
72 mac.update(array, HMAC_SIZE, array.length-HMAC_SIZE);
73 byte[] realmac=mac.doFinal();
79 long getSequenceNumber() {
87 public String toString() {
88 return "<"+getSequenceNumber()+", "+new String(getBytes())+">";