4 files changed, 115 insertions, 0 deletions

diff --git a/ws2015/eip/blaetter/10/2/PasswordCracker.java b/ws2015/eip/blaetter/10/2/PasswordCracker.java
new file mode 100644
index 0000000..0c7c094
--- /dev/null
+++ b/ws2015/eip/blaetter/10/2/PasswordCracker.java
@@ -0,0 +1,36 @@
+public class PasswordCracker {
+  
+    // dies ist der laut Angabe bekannte Hashwert des Passworts
+    public static final String HASH = "ef937752f7348a964445f60857009f881983a6af";
+    
+    public static void main(String[] args) {
+        int numProcs = Runtime.getRuntime().availableProcessors();
+        Thread[] workers = new Thread[numProcs];
+
+        Synchronizer sync = new Synchronizer(HASH);
+
+        for (int i = 0; i < numProcs; i++) {
+            workers[i] = new Thread(new PasswordCrackerThread(sync, rangeBound(numProcs, i), rangeBound(numProcs, i + 1) - 1));
+            workers[i].start();
+        }
+
+        synchronized (sync) {
+            while (! sync.hasSolution()) {
+                try {
+                    sync.wait();
+                } catch (InterruptedException e) {}
+            }
+        }
+
+        for (Thread w : workers)
+            w.interrupt();
+
+        System.out.println("Guessed this password: " + sync.getSolution());
+        System.exit(0);
+    }
+
+    public static long rangeBound(int n, int i) {
+        long upperBound = (long) 1e8;
+        return n == i ? upperBound + 1 : (upperBound / n) * i;
+    }
+}
diff --git a/ws2015/eip/blaetter/10/2/PasswordCrackerThread.java b/ws2015/eip/blaetter/10/2/PasswordCrackerThread.java
new file mode 100644
index 0000000..dcc0656
--- /dev/null
+++ b/ws2015/eip/blaetter/10/2/PasswordCrackerThread.java
@@ -0,0 +1,29 @@
+import java.util.Formatter;
+
+public class PasswordCrackerThread implements Runnable {
+
+    public final long rangeStart;
+    public final long rangeEnd;
+
+    public final Synchronizer sync;
+
+    public PasswordCrackerThread(Synchronizer s, long start, long end)
+    {
+        sync       = s;
+        rangeStart = start;
+        rangeEnd   = end;
+    }
+    
+    public void run() {
+        for (long i = rangeStart; i <= rangeEnd; i++) {
+            String guess = new Formatter().format("%8d", i).toString();
+            String digest = SHA.encrypt(guess);
+            if (digest.equals(sync.targetHash)) {
+                synchronized (sync) {
+                    sync.setSolution(i);
+                    break;
+                }
+            }
+        }
+    }
+}
diff --git a/ws2015/eip/blaetter/10/2/SHA.java b/ws2015/eip/blaetter/10/2/SHA.java
new file mode 100644
index 0000000..ad40f99
--- /dev/null
+++ b/ws2015/eip/blaetter/10/2/SHA.java
@@ -0,0 +1,28 @@
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Formatter;
+
+public class SHA {
+  
+  /**
+   * Gibt den Hashwert des Parameters zurueck - die Implementierung dieser Methode
+   * ist fuer diese Aufgabe *NICHT* relevant, braucht nicht weiter beachtet zu werden
+   * @param text auf den der Hashalgorithmus angewendet werden soll
+   * @return den Hashwert
+   */
+  public static String encrypt(String text) {
+    try {
+      MessageDigest md = MessageDigest.getInstance("SHA");
+      md.update(text.getBytes());
+      byte[] digest = md.digest();
+
+      Formatter formatter = new Formatter();
+      for (byte d: digest)
+        formatter.format("%02x", 0xFF & d);
+      return formatter.toString();
+    } catch (NoSuchAlgorithmException e) {
+      e.printStackTrace();
+      return null;
+    }
+  }
+}
\ No newline at end of file
diff --git a/ws2015/eip/blaetter/10/2/Synchronizer.java b/ws2015/eip/blaetter/10/2/Synchronizer.java
new file mode 100644
index 0000000..5efb127
--- /dev/null
+++ b/ws2015/eip/blaetter/10/2/Synchronizer.java
@@ -0,0 +1,22 @@
+public class Synchronizer {
+    public final String targetHash;
+    private Long solution = null;
+
+    public Synchronizer(String hash) { targetHash = hash; }
+
+    public synchronized void setSolution(long password)
+    {
+        solution = password;
+        this.notifyAll();
+    }
+
+    public synchronized long getSolution()
+    {
+        return solution;
+    }
+
+    public synchronized boolean hasSolution()
+    {
+        return (solution != null);
+    }
+}