* Usage: java -Dpj.np=K edu.rit.clu.keysearch.FindKeyClu2
* plaintext ciphertext partialkey n
*
K = Number of parallel processes
*
plaintext = Plaintext (128-bit hexadecimal number)
*
ciphertext = Ciphertext (128-bit hexadecimal number)
*
partialkey = Partial key (256-bit hexadecimal number)
*
n = Number of key bits to search for
*
* Whereas class {@linkplain FindKeyClu} always tests all possible keys, class
* FindKeyClu2 stops as soon as it finds the correct key.
*
* @author Alan Kaminsky
* @version 18-Jan-2012
*/
public class FindKeyClu2
{
// Prevent construction.
private FindKeyClu2()
{
}
// Shared variables.
// World communicator.
static Comm world;
static int size;
static int rank;
// Command line arguments.
static byte[] plaintext;
static byte[] ciphertext;
static byte[] partialkey;
static int n;
// Variables for doing trial encryptions.
static long keylsbs;
static long maxcounter;
static byte[] foundkey;
static byte[] trialkey;
static byte[] trialciphertext;
static AES256Cipher cipher;
// For early loop exit.
static ReplicatedBoolean found;
// Main program.
/**
* AES partial key search main program.
*/
public static void main
(String[] args)
throws Exception
{
// Start timing.
long t1 = System.currentTimeMillis();
// Initialize PJ middleware.
Comm.init (args);
world = Comm.world();
size = world.size();
rank = world.rank();
// Parse command line arguments.
if (args.length != 4) usage();
plaintext = Hex.toByteArray (args[0]);
ciphertext = Hex.toByteArray (args[1]);
partialkey = Hex.toByteArray (args[2]);
n = Integer.parseInt (args[3]);
// Make sure n is not too small or too large.
if (n < 0)
{
System.err.println ("n = " + n + " is too small");
System.exit (1);
}
if (n > 63)
{
System.err.println ("n = " + n + " is too large");
System.exit (1);
}
// Set up variables for doing trial encryptions.
keylsbs =
((partialkey[24] & 0xFFL) << 56) |
((partialkey[25] & 0xFFL) << 48) |
((partialkey[26] & 0xFFL) << 40) |
((partialkey[27] & 0xFFL) << 32) |
((partialkey[28] & 0xFFL) << 24) |
((partialkey[29] & 0xFFL) << 16) |
((partialkey[30] & 0xFFL) << 8) |
((partialkey[31] & 0xFFL) );
maxcounter = (1L << n) - 1L;
trialkey = new byte [32];
System.arraycopy (partialkey, 0, trialkey, 0, 32);
trialciphertext = new byte [16];
cipher = new AES256Cipher (trialkey);
// Set up found flag replicated in all processes.
found = new ReplicatedBoolean (BooleanOp.OR);
// Try every possible combination of low-order key bits in parallel.
new WorkerTeam().execute (new WorkerRegion()
{
public void run() throws Exception
{
execute (0L, maxcounter, new WorkerLongForLoop()
{
public void run (long first, long last) throws Exception
{
for (long counter = first; counter <= last; ++ counter)
{
// Fill in low-order key bits.
long lsbs = keylsbs | counter;
trialkey[24] = (byte) (lsbs >>> 56);
trialkey[25] = (byte) (lsbs >>> 48);
trialkey[26] = (byte) (lsbs >>> 40);
trialkey[27] = (byte) (lsbs >>> 32);
trialkey[28] = (byte) (lsbs >>> 24);
trialkey[29] = (byte) (lsbs >>> 16);
trialkey[30] = (byte) (lsbs >>> 8);
trialkey[31] = (byte) (lsbs );
// Try the key.
cipher.setKey (trialkey);
cipher.encrypt (plaintext, trialciphertext);
// If the result equals the ciphertext, we found the
// key. Set the found flag in all processes.
if (match (ciphertext, trialciphertext))
{
foundkey = new byte [32];
System.arraycopy (trialkey, 0, foundkey, 0, 32);
found.reduce (true);
}
// If key was found, exit loop.
if (found.get()) break;
}
}
});
}
});
// If we found the key, print it.
if (foundkey != null)
{
System.out.println (Hex.toString (foundkey));
}
// Stop timing.
long t2 = System.currentTimeMillis();
System.out.println ((t2-t1) + " msec (" + rank + ")");
}
// Hidden operations.
/**
* Returns true if the two byte arrays match.
*/
private static boolean match
(byte[] a,
byte[] b)
{
boolean matchsofar = true;
int n = a.length;
for (int i = 0; i < n; ++ i)
{
matchsofar = matchsofar && a[i] == b[i];
}
return matchsofar;
}
/**
* Print a usage message and exit.
*/
private static void usage()
{
System.err.println ("Usage: java -Dpj.np=