"Preventing Reverse Engineering"
Vol. 9, Issue 5, p. 39

	



Listing 1: The add() method of the Queue class after decompilation

01 public synchronized void add
        (Object item) {
02   long addWaitTime = 0;
03   while (_suspended ||
            _tail == QUEUE_FULL) {
04     long waitStart =
        System.currentTimeMillis();
05     try {
06       wait();
07     } catch (InterruptedException e)
       {  }
08     addWaitTime +=
        (System.currentTimeMillis() -
          waitStart);
09   }
10   _addWaitTime += addWaitTime;
11   // add item to backing store
12   _backingStore[_tail] = item;
13   _queueEmpty = false;
14   _tail++;
15   if (_tail >= _backingStore.length)
16     _tail = 0; // wrap
17   if (_tail == _head) {
18     _tail = -1; // special case:full
19   }
20   _queueFull =
      (_tail == -1) ? true : false;
21   notifyAll();
22 }


Listing 2: The add() method of the Queue class

01 public synchronized void add
      (Object item) {
02   long addWaitTime = 0L;
03   while (_suspended || _tail == -1) {
04     long waitStart =
          System.currentTimeMillis();
05     try {
06       this.wait();
07     } catch (InterruptedException e){
08       /* empty */
09     }
10     addWaitTime +=
        System.currentTimeMillis() -
          waitStart;
11   }
12   _addWaitTime += addWaitTime;
13   _backingStore[_tail] = item;
14   _queueEmpty = false;
15   _tail++;
16   if (_tail >= _backingStore.length)
17     _tail = 0;
18   if (_tail == _head)
19     _tail = -1;
20   _queueFull = _tail == -1;
21   this.notifyAll();
22 }


Listing 3: The add() method of the Queue class after decompilation

01 public synchronized void add
      (Object object) {
02   long l = 0L;
03   while (_suspended || _tail == -1) {
04     long l_2_ =
        System.currentTimeMillis();
05     try {
06       this.wait();
07     } catch (InterruptedException e){
08       /* empty */
09     }
10     l += System.currentTimeMillis() -
         l_2_;
11   }
12   _addWaitTime += l;
13   _backingStore[_tail] = object;
14   _queueEmpty = false;
15   _tail++;
16   if (_tail >= _backingStore.length)
17   _tail = 0;
18   if (_tail == _head)
19     _tail = -1;
20   _queueFull = _tail == -1;
21   this.notifyAll();
22 }

Listing 4: Snippets from the map file produced by yGuard

public synchronized void A(Object obj) {
  long l;
  long l1;
  for(l = 0L; J || K == - 1; l +=
      System.currentTimeMillis() - l1) {
    l1 = System.currentTimeMillis();
    try {
      wait();
    } catch(InterruptedException i) { }
  }
  S += l;
  L[K] = obj;
  T = false;
  K++;
  if(K >= L.length) {
    K = 0;
  }
  if(K == O) {
    K = -1;
  }
  R = K == -1;
  notifyAll();
}





Listing 5: The add() method of the Queue class after first 
obfuscating the bytecode using yGuard

BEFORE. . .
public class Queue extends Basic
{
 private int _head;
 private int _tail;
 private Object _backingStore[];
 private boolean _suspended;
 private boolean _queueFull;
 private boolean _queueEmpty;
 private ArrayList _suppliers;
 private ArrayList _consumers;
 private boolean _endOfInput;
 private long _addWaitTime;
 private long _removeWaitTime;
 private long _numberOfItemsProcessed;
 . . .
}
AFTER. . .
public class C extends B
{
    private int O;
    private int K;
    private Object L[];
    private boolean J;
    private boolean R;
    private boolean T;
    private ArrayList N;
    private ArrayList P;
    private boolean U;
    private long S;
    private long H;
    private long Q;
. . .
}

Listing 6

01<?xml version="1.0" encoding="UTF-8"?>
02<yguard version="1.1">
03. . .
04<expose>
05 <class name="jmxbp.ex1.Controller"/>
06 <method class="jmxbp.ex1.Controller"
  name="void main(java.lang.String[])"/>
07. . .
08</expose>
09<map>
10 <package name="jmxbp.common"
  map="A"/>
11. . .
12 <class name="jmxbp.common.Basic"
  map="B"/>
13. . .
14 <class name="jmxbp.common.Queue"
  map="C"/>
15 <field class="jmxbp.common.Queue"
  name="_head" map="O"/>
16. . .
17 <method class="jmxbp.common.Queue"
  name="void add(java.lang.Object)"
  map="A"/>
18 <method class="jmxbp.common.Queue"
  name="java.lang.Object remove(long)"
  map="A"/>
19. . .
20</map>
21</yguard>