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(Vector _entries) {
21 Slot(long _seqnum, long _machineid, byte[] _prevhmac, byte[] _hmac, Vector<Entry> _entries) {
29 Slot(long _seqnum, byte[] _bytes) {
33 static Slot decode(byte[] array, Mac mac) {
34 mac.update(array, HMAC_SIZE, array.length-HMAC_SIZE);
35 byte[] realmac=mac.doFinal();
37 ByteBuffer bb=ByteBuffer.wrap(array);
38 byte[] hmac=new byte[HMAC_SIZE];
39 byte[] prevhmac=new byte[HMAC_SIZE];
42 if (!Arrays.equals(realmac, hmac))
43 throw new Error("Invalid HMAC! Potential Attack!");
45 long seqnum=bb.getLong();
46 long machineid=bb.getLong();
47 int numentries=bb.getInt();
48 Vector<Entry> entries=new Vector();
49 for(int i=0;i<numentries;i++) {
50 entries.add(Entry.decode(bb));
53 return new Slot(seqnum, machineid, prevhmac, hmac, entries);
56 byte[] encode(Mac mac) {
57 byte[] array=new byte[SLOT_SIZE];
58 ByteBuffer bb=ByteBuffer.wrap(array);
59 bb.position(HMAC_SIZE); //Leave space for the HMACs
62 bb.putLong(machineid);
63 bb.putInt(entries.size());
64 for(Entry entry:entries) {
68 mac.update(array, HMAC_SIZE, array.length-HMAC_SIZE);
69 byte[] realmac=mac.doFinal();
75 long getSequenceNumber() {
83 public String toString() {
84 return "<"+getSequenceNumber()+", "+new String(getBytes())+">";