// $Id: $
//
// $Log: $
// Revision 1.0  1998/03/24  raif
// + start of history.
//
// $Endlog$
/*
 * Copyright (c) 1997, 1998 Systemics Ltd on behalf of
 * the Cryptix Development Team. All rights reserved.
 */
package Twofish;

import java.io.PrintWriter;
import java.security.InvalidKeyException;
import java.util.Arrays;

//...........................................................................
/**
 * Twofish is an AES candidate algorithm. It is a balanced 128-bit Feistel
 * cipher, consisting of 16 rounds. In each round, a 64-bit S-box value is
 * computed from 64 bits of the block, and this value is xored into the other
 * half of the block. The two half-blocks are then exchanged, and the next
 * round begins. Before the first round, all input bits are xored with key-
 * dependent "whitening" subkeys, and after the final round the output bits
 * are xored with other key-dependent whitening subkeys; these subkeys are
 * not used anywhere else in the algorithm.<p>
 *
 * Twofish was submitted by Bruce Schneier, Doug Whiting, John Kelsey, Chris
 * Hall and David Wagner.<p>
 *
 * Reference:<ol>
 *  <li>TWOFISH2.C -- Optimized C API calls for TWOFISH AES submission,
 *  Version 1.00, April 1998, by Doug Whiting.</ol><p>
 *
 * <b>Copyright</b> &copy; 1998
 * <a href="http://www.systemics.com/">Systemics Ltd</a> on behalf of the
 * <a href="http://www.systemics.com/docs/cryptix/">Cryptix Development Team</a>.
 * <br>All rights reserved.<p>
 *
 * <b>$Revision: $</b>
 * @author  Raif S. Naffah
 */
public final class Twofish_Algorithm // implicit no-argument constructor
{
// Debugging methods and variables
//...........................................................................

   static final String NAME = "Twofish_Algorithm";
   static final boolean IN = true, OUT = false;

   static final boolean DEBUG = Twofish_Properties.GLOBAL_DEBUG;
   static final int debuglevel = DEBUG ? Twofish_Properties.getLevel(NAME) : 0;
   static final PrintWriter err = DEBUG ? Twofish_Properties.getOutput() : null;

   static final boolean TRACE = Twofish_Properties.isTraceable(NAME);

   static void debug (String s) { err.println(">>> "+NAME+": "+s); }
   static void trace (boolean in, String s) {
      if (TRACE) err.println((in?"==> ":"<== ")+NAME+"."+s);
   }
   static void trace (String s) { if (TRACE) err.println("<=> "+NAME+"."+s); }


// Constants and variables
//...........................................................................

   static final int BLOCK_SIZE = 16; // bytes in a data-block
   private static final int ROUNDS = 16;
   private static final int MAX_ROUNDS = 16; // max # rounds (for allocating subkeys)
   
   /* Subkey array indices */
   private static final int INPUT_WHITEN = 0;
   private static final int OUTPUT_WHITEN = INPUT_WHITEN +  BLOCK_SIZE/4;
   private static final int ROUND_SUBKEYS = OUTPUT_WHITEN + BLOCK_SIZE/4; // 2*(# rounds)

   private static final int TOTAL_SUBKEYS = ROUND_SUBKEYS + 2*MAX_ROUNDS;

   private static final int SK_STEP = 0x02020202;
   private static final int SK_BUMP = 0x01010101;
   private static final int SK_ROTL = 9;

   /** Fixed 8x8 permutation S-boxes */
   private static final byte[][] P = new byte[][] {
      {  // p0
         (byte) 0xA9, (byte) 0x67, (byte) 0xB3, (byte) 0xE8,
         (byte) 0x04, (byte) 0xFD, (byte) 0xA3, (byte) 0x76,
         (byte) 0x9A, (byte) 0x92, (byte) 0x80, (byte) 0x78,
         (byte) 0xE4, (byte) 0xDD, (byte) 0xD1, (byte) 0x38,
         (byte) 0x0D, (byte) 0xC6, (byte) 0x35, (byte) 0x98,
         (byte) 0x18, (byte) 0xF7, (byte) 0xEC, (byte) 0x6C,
         (byte) 0x43, (byte) 0x75, (byte) 0x37, (byte) 0x26,
         (byte) 0xFA, (byte) 0x13, (byte) 0x94, (byte) 0x48,
         (byte) 0xF2, (byte) 0xD0, (byte) 0x8B, (byte) 0x30,
         (byte) 0x84, (byte) 0x54, (byte) 0xDF, (byte) 0x23,
         (byte) 0x19, (byte) 0x5B, (byte) 0x3D, (byte) 0x59,
         (byte) 0xF3, (byte) 0xAE, (byte) 0xA2, (byte) 0x82,
         (byte) 0x63, (byte) 0x01, (byte) 0x83, (byte) 0x2E,
         (byte) 0xD9, (byte) 0x51, (byte) 0x9B, (byte) 0x7C,
         (byte) 0xA6, (byte) 0xEB, (byte) 0xA5, (byte) 0xBE,
         (byte) 0x16, (byte) 0x0C, (byte) 0xE3, (byte) 0x61,
         (byte) 0xC0, (byte) 0x8C, (byte) 0x3A, (byte) 0xF5,
         (byte) 0x73, (byte) 0x2C, (byte) 0x25, (byte) 0x0B,
         (byte) 0xBB, (byte) 0x4E, (byte) 0x89, (byte) 0x6B,
         (byte) 0x53, (byte) 0x6A, (byte) 0xB4, (byte) 0xF1,
         (byte) 0xE1, (byte) 0xE6, (byte) 0xBD, (byte) 0x45,
         (byte) 0xE2, (byte) 0xF4, (byte) 0xB6, (byte) 0x66,
         (byte) 0xCC, (byte) 0x95, (byte) 0x03, (byte) 0x56,
         (byte) 0xD4, (byte) 0x1C, (byte) 0x1E, (byte) 0xD7,
         (byte) 0xFB, (byte) 0xC3, (byte) 0x8E, (byte) 0xB5,
         (byte) 0xE9, (byte) 0xCF, (byte) 0xBF, (byte) 0xBA,
         (byte) 0xEA, (byte) 0x77, (byte) 0x39, (byte) 0xAF,
         (byte) 0x33, (byte) 0xC9, (byte) 0x62, (byte) 0x71,
         (byte) 0x81, (byte) 0x79, (byte) 0x09, (byte) 0xAD,
         (byte) 0x24, (byte) 0xCD, (byte) 0xF9, (byte) 0xD8,
         (byte) 0xE5, (byte) 0xC5, (byte) 0xB9, (byte) 0x4D,
         (byte) 0x44, (byte) 0x08, (byte) 0x86, (byte) 0xE7,
         (byte) 0xA1, (byte) 0x1D, (byte) 0xAA, (byte) 0xED,
         (byte) 0x06, (byte) 0x70, (byte) 0xB2, (byte) 0xD2,
         (byte) 0x41, (byte) 0x7B, (byte) 0xA0, (byte) 0x11,
         (byte) 0x31, (byte) 0xC2, (byte) 0x27, (byte) 0x90,
         (byte) 0x20, (byte) 0xF6, (byte) 0x60, (byte) 0xFF,
         (byte) 0x96, (byte) 0x5C, (byte) 0xB1, (byte) 0xAB,
         (byte) 0x9E, (byte) 0x9C, (byte) 0x52, (byte) 0x1B,
         (byte) 0x5F, (byte) 0x93, (byte) 0x0A, (byte) 0xEF,
         (byte) 0x91, (byte) 0x85, (byte) 0x49, (byte) 0xEE,
         (byte) 0x2D, (byte) 0x4F, (byte) 0x8F, (byte) 0x3B,
         (byte) 0x47, (byte) 0x87, (byte) 0x6D, (byte) 0x46,
         (byte) 0xD6, (byte) 0x3E, (byte) 0x69, (byte) 0x64,
         (byte) 0x2A, (byte) 0xCE, (byte) 0xCB, (byte) 0x2F,
         (byte) 0xFC, (byte) 0x97, (byte) 0x05, (byte) 0x7A,
         (byte) 0xAC, (byte) 0x7F, (byte) 0xD5, (byte) 0x1A,
         (byte) 0x4B, (byte) 0x0E, (byte) 0xA7, (byte) 0x5A,
         (byte) 0x28, (byte) 0x14, (byte) 0x3F, (byte) 0x29,
         (byte) 0x88, (byte) 0x3C, (byte) 0x4C, (byte) 0x02,
         (byte) 0xB8, (byte) 0xDA, (byte) 0xB0, (byte) 0x17,
         (byte) 0x55, (byte) 0x1F, (byte) 0x8A, (byte) 0x7D,
         (byte) 0x57, (byte) 0xC7, (byte) 0x8D, (byte) 0x74,
         (byte) 0xB7, (byte) 0xC4, (byte) 0x9F, (byte) 0x72,
         (byte) 0x7E, (byte) 0x15, (byte) 0x22, (byte) 0x12,
         (byte) 0x58, (byte) 0x07, (byte) 0x99, (byte) 0x34,
         (byte) 0x6E, (byte) 0x50, (byte) 0xDE, (byte) 0x68,
         (byte) 0x65, (byte) 0xBC, (byte) 0xDB, (byte) 0xF8,
         (byte) 0xC8, (byte) 0xA8, (byte) 0x2B, (byte) 0x40,
         (byte) 0xDC, (byte) 0xFE, (byte) 0x32, (byte) 0xA4,
         (byte) 0xCA, (byte) 0x10, (byte) 0x21, (byte) 0xF0,
         (byte) 0xD3, (byte) 0x5D, (byte) 0x0F, (byte) 0x00,
         (byte) 0x6F, (byte) 0x9D, (byte) 0x36, (byte) 0x42,
         (byte) 0x4A, (byte) 0x5E, (byte) 0xC1, (byte) 0xE0
      },
      {  // p1
         (byte) 0x75, (byte) 0xF3, (byte) 0xC6, (byte) 0xF4,
         (byte) 0xDB, (byte) 0x7B, (byte) 0xFB, (byte) 0xC8,
         (byte) 0x4A, (byte) 0xD3, (byte) 0xE6, (byte) 0x6B,
         (byte) 0x45, (byte) 0x7D, (byte) 0xE8, (byte) 0x4B,
         (byte) 0xD6, (byte) 0x32, (byte) 0xD8, (byte) 0xFD,
         (byte) 0x37, (byte) 0x71, (byte) 0xF1, (byte) 0xE1,
         (byte) 0x30, (byte) 0x0F, (byte) 0xF8, (byte) 0x1B,
         (byte) 0x87, (byte) 0xFA, (byte) 0x06, (byte) 0x3F,
         (byte) 0x5E, (byte) 0xBA, (byte) 0xAE, (byte) 0x5B,
         (byte) 0x8A, (byte) 0x00, (byte) 0xBC, (byte) 0x9D,
         (byte) 0x6D, (byte) 0xC1, (byte) 0xB1, (byte) 0x0E,
         (byte) 0x80, (byte) 0x5D, (byte) 0xD2, (byte) 0xD5,
         (byte) 0xA0, (byte) 0x84, (byte) 0x07, (byte) 0x14,
         (byte) 0xB5, (byte) 0x90, (byte) 0x2C, (byte) 0xA3,
         (byte) 0xB2, (byte) 0x73, (byte) 0x4C, (byte) 0x54,
         (byte) 0x92, (byte) 0x74, (byte) 0x36, (byte) 0x51,
         (byte) 0x38, (byte) 0xB0, (byte) 0xBD, (byte) 0x5A,
         (byte) 0xFC, (byte) 0x60, (byte) 0x62, (byte) 0x96,
         (byte) 0x6C, (byte) 0x42, (byte) 0xF7, (byte) 0x10,
         (byte) 0x7C, (byte) 0x28, (byte) 0x27, (byte) 0x8C,
         (byte) 0x13, (byte) 0x95, (byte) 0x9C, (byte) 0xC7,
         (byte) 0x24, (byte) 0x46, (byte) 0x3B, (byte) 0x70,
         (byte) 0xCA, (byte) 0xE3, (byte) 0x85, (byte) 0xCB,
         (byte) 0x11, (byte) 0xD0, (byte) 0x93, (byte) 0xB8,
         (byte) 0xA6, (byte) 0x83, (byte) 0x20, (byte) 0xFF,
         (byte) 0x9F, (byte) 0x77, (byte) 0xC3, (byte) 0xCC,
         (byte) 0x03, (byte) 0x6F, (byte) 0x08, (byte) 0xBF,
         (byte) 0x40, (byte) 0xE7, (byte) 0x2B, (byte) 0xE2,
         (byte) 0x79, (byte) 0x0C, (byte) 0xAA, (byte) 0x82,
         (byte) 0x41, (byte) 0x3A, (byte) 0xEA, (byte) 0xB9,
         (byte) 0xE4, (byte) 0x9A, (byte) 0xA4, (byte) 0x97,
         (byte) 0x7E, (byte) 0xDA, (byte) 0x7A, (byte) 0x17,
         (byte) 0x66, (byte) 0x94, (byte) 0xA1, (byte) 0x1D,
         (byte) 0x3D, (byte) 0xF0, (byte) 0xDE, (byte) 0xB3,
         (byte) 0x0B, (byte) 0x72, (byte) 0xA7, (byte) 0x1C,
         (byte) 0xEF, (byte) 0xD1, (byte) 0x53, (byte) 0x3E,
         (byte) 0x8F, (byte) 0x33, (byte) 0x26, (byte) 0x5F,
         (byte) 0xEC, (byte) 0x76, (byte) 0x2A, (byte) 0x49,
         (byte) 0x81, (byte) 0x88, (byte) 0xEE, (byte) 0x21,
         (byte) 0xC4, (byte) 0x1A, (byte) 0xEB, (byte) 0xD9,
         (byte) 0xC5, (byte) 0x39, (byte) 0x99, (byte) 0xCD,
         (byte) 0xAD, (byte) 0x31, (byte) 0x8B, (byte) 0x01,
         (byte) 0x18, (byte) 0x23, (byte) 0xDD, (byte) 0x1F,
         (byte) 0x4E, (byte) 0x2D, (byte) 0xF9, (byte) 0x48,
         (byte) 0x4F, (byte) 0xF2, (byte) 0x65, (byte) 0x8E,
         (byte) 0x78, (byte) 0x5C, (byte) 0x58, (byte) 0x19,
         (byte) 0x8D, (byte) 0xE5, (byte) 0x98, (byte) 0x57,
         (byte) 0x67, (byte) 0x7F, (byte) 0x05, (byte) 0x64,
         (byte) 0xAF, (byte) 0x63, (byte) 0xB6, (byte) 0xFE,
         (byte) 0xF5, (byte) 0xB7, (byte) 0x3C, (byte) 0xA5,
         (byte) 0xCE, (byte) 0xE9, (byte) 0x68, (byte) 0x44,
         (byte) 0xE0, (byte) 0x4D, (byte) 0x43, (byte) 0x69,
         (byte) 0x29, (byte) 0x2E, (byte) 0xAC, (byte) 0x15,
         (byte) 0x59, (byte) 0xA8, (byte) 0x0A, (byte) 0x9E,
         (byte) 0x6E, (byte) 0x47, (byte) 0xDF, (byte) 0x34,
         (byte) 0x35, (byte) 0x6A, (byte) 0xCF, (byte) 0xDC,
         (byte) 0x22, (byte) 0xC9, (byte) 0xC0, (byte) 0x9B,
         (byte) 0x89, (byte) 0xD4, (byte) 0xED, (byte) 0xAB,
         (byte) 0x12, (byte) 0xA2, (byte) 0x0D, (byte) 0x52,
         (byte) 0xBB, (byte) 0x02, (byte) 0x2F, (byte) 0xA9,
         (byte) 0xD7, (byte) 0x61, (byte) 0x1E, (byte) 0xB4,
         (byte) 0x50, (byte) 0x04, (byte) 0xF6, (byte) 0xC2,
         (byte) 0x16, (byte) 0x25, (byte) 0x86, (byte) 0x56,
         (byte) 0x55, (byte) 0x09, (byte) 0xBE, (byte) 0x91
      }
   };

   /**
    * Define the fixed p0/p1 permutations used in keyed S-box lookup.
    * By changing the following constant definitions, the S-boxes will
    * automatically get changed in the Twofish engine.
    */
   private static final int P_00 = 1;
   private static final int P_01 = 0;
   private static final int P_02 = 0;
   private static final int P_03 = P_01 ^ 1;
   private static final int P_04 = 1;

   private static final int P_10 = 0;
   private static final int P_11 = 0;
   private static final int P_12 = 1;
   private static final int P_13 = P_11 ^ 1;
   private static final int P_14 = 0;

   private static final int P_20 = 1;
   private static final int P_21 = 1;
   private static final int P_22 = 0;
   private static final int P_23 = P_21 ^ 1;
   private static final int P_24 = 0;

   private static final int P_30 = 0;
   private static final int P_31 = 1;
   private static final int P_32 = 1;
   private static final int P_33 = P_31 ^ 1;
   private static final int P_34 = 1;

   /** Primitive polynomial for GF(256) */
   private static final int GF256_FDBK =   0x169;
   private static final int GF256_FDBK_2 = 0x169 / 2;
   private static final int GF256_FDBK_4 = 0x169 / 4;

   /** MDS matrix */
   private static final int[][] MDS = new int[4][256]; // blank final

   private static final int RS_GF_FDBK = 0x14D; // field generator

   /** data for hexadecimal visualisation. */
   private static final char[] HEX_DIGITS = {
      '0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'
   };


// Static code - to intialise the MDS matrix
//...........................................................................

   static {
      long time = System.currentTimeMillis();

if (DEBUG && debuglevel > 6) {
System.out.println("Algorithm Name: "+Twofish_Properties.FULL_NAME);
System.out.println("Electronic Codebook (ECB) Mode");
System.out.println();
}
      //
      // precompute the MDS matrix
      //
      int[] m1 = new int[2];
      int[] mX = new int[2];
      int[] mY = new int[2];
      int i, j;
      for (i = 0; i < 256; i++) {
         j = P[0][i]       & 0xFF; // compute all the matrix elements
         m1[0] = j;
         mX[0] = Mx_X( j ) & 0xFF;
         mY[0] = Mx_Y( j ) & 0xFF;

         j = P[1][i]       & 0xFF;
         m1[1] = j;
         mX[1] = Mx_X( j ) & 0xFF;
         mY[1] = Mx_Y( j ) & 0xFF;

         MDS[0][i] = m1[P_00] <<  0 | // fill matrix w/ above elements
                     mX[P_00] <<  8 |
                     mY[P_00] << 16 |
                     mY[P_00] << 24;
         MDS[1][i] = mY[P_10] <<  0 |
                     mY[P_10] <<  8 |
                     mX[P_10] << 16 |
                     m1[P_10] << 24;
         MDS[2][i] = mX[P_20] <<  0 |
                     mY[P_20] <<  8 |
                     m1[P_20] << 16 |
                     mY[P_20] << 24;
         MDS[3][i] = mX[P_30] <<  0 |
                     m1[P_30] <<  8 |
                     mY[P_30] << 16 |
                     mX[P_30] << 24;
      }
      
      time = System.currentTimeMillis() - time;

if (DEBUG && debuglevel > 8) {
System.out.println("==========");
System.out.println();
System.out.println("Static Data");
System.out.println();
System.out.println("MDS[0][]:"); for(i=0;i<64;i++) { for(j=0;j<4;j++) System.out.print("0x"+intToString(MDS[0][i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("MDS[1][]:"); for(i=0;i<64;i++) { for(j=0;j<4;j++) System.out.print("0x"+intToString(MDS[1][i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("MDS[2][]:"); for(i=0;i<64;i++) { for(j=0;j<4;j++) System.out.print("0x"+intToString(MDS[2][i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("MDS[3][]:"); for(i=0;i<64;i++) { for(j=0;j<4;j++) System.out.print("0x"+intToString(MDS[3][i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("Total initialization time: "+time+" ms.");
System.out.println();
}
   }

   private static final int LFSR1( int x ) {
      return (x >> 1) ^
            ((x & 0x01) != 0 ? GF256_FDBK_2 : 0);
   }

   private static final int LFSR2( int x ) {
      return (x >> 2) ^
            ((x & 0x02) != 0 ? GF256_FDBK_2 : 0) ^
            ((x & 0x01) != 0 ? GF256_FDBK_4 : 0);
   }

   private static final int Mx_1( int x ) { return x; }
   private static final int Mx_X( int x ) { return x ^ LFSR2(x); }            // 5B
   private static final int Mx_Y( int x ) { return x ^ LFSR1(x) ^ LFSR2(x); } // EF


// Basic API methods
//...........................................................................

   /**
    * Expand a user-supplied key material into a session key.
    *
    * @param k  The 64/128/192/256-bit user-key to use.
    * @return  This cipher's round keys.
    * @exception  InvalidKeyException  If the key is invalid.
    */
   public static synchronized Object makeKey (byte[] k)
   throws InvalidKeyException {
if (DEBUG) trace(IN, "makeKey("+ Arrays.toString(k) +")");
      if (k == null)
         throw new InvalidKeyException("Empty key");
      int length = k.length;
      if (!(length == 8 || length == 16 || length == 24 || length == 32))
          throw new InvalidKeyException("Incorrect key length");

if (DEBUG && debuglevel > 7) {
System.out.println("Intermediate Session Key Values");
System.out.println();
System.out.println("Raw="+toString(k));
System.out.println();
}
      int k64Cnt = length / 8;
      int subkeyCnt = ROUND_SUBKEYS + 2*ROUNDS;
      int[] k32e = new int[4]; // even 32-bit entities
      int[] k32o = new int[4]; // odd 32-bit entities
      int[] sBoxKey = new int[4];
      //
      // split user key material into even and odd 32-bit entities and
      // compute S-box keys using (12, 8) Reed-Solomon code over GF(256)
      //
      int i, j, offset = 0;
      for (i = 0, j = k64Cnt-1; i < 4 && offset < length; i++, j--) {
         k32e[i] = (k[offset++] & 0xFF)       |
                   (k[offset++] & 0xFF) <<  8 |
                   (k[offset++] & 0xFF) << 16 |
                   (k[offset++] & 0xFF) << 24;
         k32o[i] = (k[offset++] & 0xFF)       |
                   (k[offset++] & 0xFF) <<  8 |
                   (k[offset++] & 0xFF) << 16 |
                   (k[offset++] & 0xFF) << 24;
         sBoxKey[j] = RS_MDS_Encode( k32e[i], k32o[i] ); // reverse order
      }
      // compute the round decryption subkeys for PHT. these same subkeys
      // will be used in encryption but will be applied in reverse order.
      int q, A, B;
      int[] subKeys = new int[subkeyCnt];
      for (i = q = 0; i < subkeyCnt/2; i++, q += SK_STEP) {
         A = F32( k64Cnt, q        , k32e ); // A uses even key entities
         B = F32( k64Cnt, q+SK_BUMP, k32o ); // B uses odd  key entities
         B = B << 8 | B >>> 24;
         A += B;
         subKeys[2*i    ] = A;               // combine with a PHT
         A += B;
         subKeys[2*i + 1] = A << SK_ROTL | A >>> (32-SK_ROTL);
      }
      //
      // fully expand the table for speed
      //
      int k0 = sBoxKey[0];
      int k1 = sBoxKey[1];
      int k2 = sBoxKey[2];
      int k3 = sBoxKey[3];
      int b0, b1, b2, b3;
      int[] sBox = new int[4 * 256];
      for (i = 0; i < 256; i++) {
         b0 = b1 = b2 = b3 = i;
         switch (k64Cnt & 3) {
         case 1:
            sBox[      2*i  ] = MDS[0][(P[P_01][b0] & 0xFF) ^ b0(k0)];
            sBox[      2*i+1] = MDS[1][(P[P_11][b1] & 0xFF) ^ b1(k0)];
            sBox[0x200+2*i  ] = MDS[2][(P[P_21][b2] & 0xFF) ^ b2(k0)];
            sBox[0x200+2*i+1] = MDS[3][(P[P_31][b3] & 0xFF) ^ b3(k0)];
            break;
         case 0: // same as 4
            b0 = (P[P_04][b0] & 0xFF) ^ b0(k3);
            b1 = (P[P_14][b1] & 0xFF) ^ b1(k3);
            b2 = (P[P_24][b2] & 0xFF) ^ b2(k3);
            b3 = (P[P_34][b3] & 0xFF) ^ b3(k3);
         case 3:
            b0 = (P[P_03][b0] & 0xFF) ^ b0(k2);
            b1 = (P[P_13][b1] & 0xFF) ^ b1(k2);
            b2 = (P[P_23][b2] & 0xFF) ^ b2(k2);
            b3 = (P[P_33][b3] & 0xFF) ^ b3(k2);
         case 2: // 128-bit keys
            sBox[      2*i  ] = MDS[0][(P[P_01][(P[P_02][b0] & 0xFF) ^ b0(k1)] & 0xFF) ^ b0(k0)];
            sBox[      2*i+1] = MDS[1][(P[P_11][(P[P_12][b1] & 0xFF) ^ b1(k1)] & 0xFF) ^ b1(k0)];
            sBox[0x200+2*i  ] = MDS[2][(P[P_21][(P[P_22][b2] & 0xFF) ^ b2(k1)] & 0xFF) ^ b2(k0)];
            sBox[0x200+2*i+1] = MDS[3][(P[P_31][(P[P_32][b3] & 0xFF) ^ b3(k1)] & 0xFF) ^ b3(k0)];
         }
      }

      Object sessionKey = new Object[] { sBox, subKeys };

if (DEBUG && debuglevel > 7) {
System.out.println("S-box[]:");
for(i=0;i<64;i++) { for(j=0;j<4;j++) System.out.print("0x"+intToString(sBox[i*4+j])+", "); System.out.println();}
System.out.println();
for(i=0;i<64;i++) { for(j=0;j<4;j++) System.out.print("0x"+intToString(sBox[256+i*4+j])+", "); System.out.println();}
System.out.println();
for(i=0;i<64;i++) { for(j=0;j<4;j++) System.out.print("0x"+intToString(sBox[512+i*4+j])+", "); System.out.println();}
System.out.println();
for(i=0;i<64;i++) { for(j=0;j<4;j++) System.out.print("0x"+intToString(sBox[768+i*4+j])+", "); System.out.println();}
System.out.println();
System.out.println("User (odd, even) keys  --> S-Box keys:");
for(i=0;i<k64Cnt;i++) { System.out.println("0x"+intToString(k32o[i])+"  0x"+intToString(k32e[i])+" --> 0x"+intToString(sBoxKey[k64Cnt-1-i])); }
System.out.println();
System.out.println("Round keys:");
for(i=0;i<ROUND_SUBKEYS + 2*ROUNDS;i+=2) { System.out.println("0x"+intToString(subKeys[i])+"  0x"+intToString(subKeys[i+1])); }
System.out.println();

}
if (DEBUG) trace(OUT, "makeKey()");
      return sessionKey;
   }

   /**
    * Encrypt exactly one block of plaintext.
    *
    * @param in        The plaintext.
    * @param inOffset   Index of in from which to start considering data.
    * @param sessionKey  The session key to use for encryption.
    * @return The ciphertext generated from a plaintext using the session key.
    */
   public static byte[]
   blockEncrypt (byte[] in, int inOffset, Object sessionKey) {
if (DEBUG) trace(IN, "blockEncrypt("+Arrays.toString(in)+", "+inOffset+", "+sessionKey+")");
      Object[] sk = (Object[]) sessionKey; // extract S-box and session key
      int[] sBox = (int[]) sk[0];
      int[] sKey = (int[]) sk[1];

if (DEBUG && debuglevel > 6) System.out.println("PT="+toString(in, inOffset, BLOCK_SIZE));

      int x0 = (in[inOffset++] & 0xFF)       |
               (in[inOffset++] & 0xFF) <<  8 |
               (in[inOffset++] & 0xFF) << 16 |
               (in[inOffset++] & 0xFF) << 24;
      int x1 = (in[inOffset++] & 0xFF)       |
               (in[inOffset++] & 0xFF) <<  8 |
               (in[inOffset++] & 0xFF) << 16 |
               (in[inOffset++] & 0xFF) << 24;
      int x2 = (in[inOffset++] & 0xFF)       |
               (in[inOffset++] & 0xFF) <<  8 |
               (in[inOffset++] & 0xFF) << 16 |
               (in[inOffset++] & 0xFF) << 24;
      int x3 = (in[inOffset++] & 0xFF)       |
               (in[inOffset++] & 0xFF) <<  8 |
               (in[inOffset++] & 0xFF) << 16 |
               (in[inOffset++] & 0xFF) << 24;

      x0 ^= sKey[INPUT_WHITEN    ];
      x1 ^= sKey[INPUT_WHITEN + 1];
      x2 ^= sKey[INPUT_WHITEN + 2];
      x3 ^= sKey[INPUT_WHITEN + 3];
if (DEBUG && debuglevel > 6) System.out.println("PTw="+intToString(x0)+intToString(x1)+intToString(x2)+intToString(x3));

      int t0, t1;
      int k = ROUND_SUBKEYS;
      for (int R = 0; R < ROUNDS; R += 2) {
         t0 = Fe32( sBox, x0, 0 );
         t1 = Fe32( sBox, x1, 3 );
         x2 ^= t0 + t1 + sKey[k++];
         x2  = x2 >>> 1 | x2 << 31;
         x3  = x3 << 1 | x3 >>> 31;
         x3 ^= t0 + 2*t1 + sKey[k++];
if (DEBUG && debuglevel > 6) System.out.println("CT"+(R)+"="+intToString(x0)+intToString(x1)+intToString(x2)+intToString(x3));

         t0 = Fe32( sBox, x2, 0 );
         t1 = Fe32( sBox, x3, 3 );
         x0 ^= t0 + t1 + sKey[k++];
         x0  = x0 >>> 1 | x0 << 31;
         x1  = x1 << 1 | x1 >>> 31;
         x1 ^= t0 + 2*t1 + sKey[k++];
if (DEBUG && debuglevel > 6) System.out.println("CT"+(R+1)+"="+intToString(x0)+intToString(x1)+intToString(x2)+intToString(x3));
      }
      x2 ^= sKey[OUTPUT_WHITEN    ];
      x3 ^= sKey[OUTPUT_WHITEN + 1];
      x0 ^= sKey[OUTPUT_WHITEN + 2];
      x1 ^= sKey[OUTPUT_WHITEN + 3];
if (DEBUG && debuglevel > 6) System.out.println("CTw="+intToString(x0)+intToString(x1)+intToString(x2)+intToString(x3));

      byte[] result = new byte[] {
         (byte) x2, (byte)(x2 >>> 8), (byte)(x2 >>> 16), (byte)(x2 >>> 24),
         (byte) x3, (byte)(x3 >>> 8), (byte)(x3 >>> 16), (byte)(x3 >>> 24),
         (byte) x0, (byte)(x0 >>> 8), (byte)(x0 >>> 16), (byte)(x0 >>> 24),
         (byte) x1, (byte)(x1 >>> 8), (byte)(x1 >>> 16), (byte)(x1 >>> 24),
      };

if (DEBUG && debuglevel > 6) {
System.out.println("CT="+toString(result));
System.out.println();
}
if (DEBUG) trace(OUT, "blockEncrypt()");
      return result;
   }

   /**
    * Decrypt exactly one block of ciphertext.
    *
    * @param in        The ciphertext.
    * @param inOffset   Index of in from which to start considering data.
    * @param sessionKey  The session key to use for decryption.
    * @return The plaintext generated from a ciphertext using the session key.
    */
   public static byte[]
   blockDecrypt (byte[] in, int inOffset, Object sessionKey) {
if (DEBUG) trace(IN, "blockDecrypt("+Arrays.toString(in)+", "+inOffset+", "+sessionKey+")");
      Object[] sk = (Object[]) sessionKey; // extract S-box and session key
      int[] sBox = (int[]) sk[0];
      int[] sKey = (int[]) sk[1];

if (DEBUG && debuglevel > 6) System.out.println("CT="+toString(in, inOffset, BLOCK_SIZE));

      int x2 = (in[inOffset++] & 0xFF)       |
               (in[inOffset++] & 0xFF) <<  8 |
               (in[inOffset++] & 0xFF) << 16 |
               (in[inOffset++] & 0xFF) << 24;
      int x3 = (in[inOffset++] & 0xFF)       |
               (in[inOffset++] & 0xFF) <<  8 |
               (in[inOffset++] & 0xFF) << 16 |
               (in[inOffset++] & 0xFF) << 24;
      int x0 = (in[inOffset++] & 0xFF)       |
               (in[inOffset++] & 0xFF) <<  8 |
               (in[inOffset++] & 0xFF) << 16 |
               (in[inOffset++] & 0xFF) << 24;
      int x1 = (in[inOffset++] & 0xFF)       |
               (in[inOffset++] & 0xFF) <<  8 |
               (in[inOffset++] & 0xFF) << 16 |
               (in[inOffset++] & 0xFF) << 24;

      x2 ^= sKey[OUTPUT_WHITEN    ];
      x3 ^= sKey[OUTPUT_WHITEN + 1];
      x0 ^= sKey[OUTPUT_WHITEN + 2];
      x1 ^= sKey[OUTPUT_WHITEN + 3];
if (DEBUG && debuglevel > 6) System.out.println("CTw="+intToString(x2)+intToString(x3)+intToString(x0)+intToString(x1));

      int k = ROUND_SUBKEYS + 2*ROUNDS - 1;
      int t0, t1;
      for (int R = 0; R < ROUNDS; R += 2) {
         t0 = Fe32( sBox, x2, 0 );
         t1 = Fe32( sBox, x3, 3 );
         x1 ^= t0 + 2*t1 + sKey[k--];
         x1  = x1 >>> 1 | x1 << 31;
         x0  = x0 << 1 | x0 >>> 31;
         x0 ^= t0 + t1 + sKey[k--];
if (DEBUG && debuglevel > 6) System.out.println("PT"+(ROUNDS-R)+"="+intToString(x2)+intToString(x3)+intToString(x0)+intToString(x1));

         t0 = Fe32( sBox, x0, 0 );
         t1 = Fe32( sBox, x1, 3 );
         x3 ^= t0 + 2*t1 + sKey[k--];
         x3  = x3 >>> 1 | x3 << 31;
         x2  = x2 << 1 | x2 >>> 31;
         x2 ^= t0 + t1 + sKey[k--];
if (DEBUG && debuglevel > 6) System.out.println("PT"+(ROUNDS-R-1)+"="+intToString(x2)+intToString(x3)+intToString(x0)+intToString(x1));
      }
      x0 ^= sKey[INPUT_WHITEN    ];
      x1 ^= sKey[INPUT_WHITEN + 1];
      x2 ^= sKey[INPUT_WHITEN + 2];
      x3 ^= sKey[INPUT_WHITEN + 3];
if (DEBUG && debuglevel > 6) System.out.println("PTw="+intToString(x2)+intToString(x3)+intToString(x0)+intToString(x1));

      byte[] result = new byte[] {
         (byte) x0, (byte)(x0 >>> 8), (byte)(x0 >>> 16), (byte)(x0 >>> 24), 
         (byte) x1, (byte)(x1 >>> 8), (byte)(x1 >>> 16), (byte)(x1 >>> 24), 
         (byte) x2, (byte)(x2 >>> 8), (byte)(x2 >>> 16), (byte)(x2 >>> 24), 
         (byte) x3, (byte)(x3 >>> 8), (byte)(x3 >>> 16), (byte)(x3 >>> 24),
      };

if (DEBUG && debuglevel > 6) {
System.out.println("PT="+toString(result));
System.out.println();
}
if (DEBUG) trace(OUT, "blockDecrypt()");
      return result;
   }

   /** A basic symmetric encryption/decryption test. */ 
   public static boolean self_test() { return self_test(BLOCK_SIZE); }


// own methods
//...........................................................................

   private static final int b0( int x ) { return  x         & 0xFF; }
   private static final int b1( int x ) { return (x >>>  8) & 0xFF; }
   private static final int b2( int x ) { return (x >>> 16) & 0xFF; }
   private static final int b3( int x ) { return (x >>> 24) & 0xFF; }

   /**
    * Use (12, 8) Reed-Solomon code over GF(256) to produce a key S-box
    * 32-bit entity from two key material 32-bit entities.
    *
    * @param  k0  1st 32-bit entity.
    * @param  k1  2nd 32-bit entity.
    * @return  Remainder polynomial generated using RS code
    */
   private static final int RS_MDS_Encode( int k0, int k1) {
      int r = k1;
      for (int i = 0; i < 4; i++) // shift 1 byte at a time
         r = RS_rem( r );
      r ^= k0;
      for (int i = 0; i < 4; i++)
         r = RS_rem( r );
      return r;
   }

   /*
    * Reed-Solomon code parameters: (12, 8) reversible code:<p>
    * <pre>
    *   g(x) = x**4 + (a + 1/a) x**3 + a x**2 + (a + 1/a) x + 1
    * </pre>
    * where a = primitive root of field generator 0x14D
    */
   private static final int RS_rem( int x ) {
      int b  =  (x >>> 24) & 0xFF;
      int g2 = ((b  <<  1) ^ ( (b & 0x80) != 0 ? RS_GF_FDBK : 0 )) & 0xFF;
      int g3 =  (b >>>  1) ^ ( (b & 0x01) != 0 ? (RS_GF_FDBK >>> 1) : 0 ) ^ g2 ;
      int result = (x << 8) ^ (g3 << 24) ^ (g2 << 16) ^ (g3 << 8) ^ b;
      return result;
   }

   private static final int F32( int k64Cnt, int x, int[] k32 ) {
      int b0 = b0(x);
      int b1 = b1(x);
      int b2 = b2(x);
      int b3 = b3(x);
      int k0 = k32[0];
      int k1 = k32[1];
      int k2 = k32[2];
      int k3 = k32[3];

      int result = 0;
      switch (k64Cnt & 3) {
      case 1:
         result =
            MDS[0][(P[P_01][b0] & 0xFF) ^ b0(k0)] ^
            MDS[1][(P[P_11][b1] & 0xFF) ^ b1(k0)] ^
            MDS[2][(P[P_21][b2] & 0xFF) ^ b2(k0)] ^
            MDS[3][(P[P_31][b3] & 0xFF) ^ b3(k0)];
         break;
      case 0:  // same as 4
         b0 = (P[P_04][b0] & 0xFF) ^ b0(k3);
         b1 = (P[P_14][b1] & 0xFF) ^ b1(k3);
         b2 = (P[P_24][b2] & 0xFF) ^ b2(k3);
         b3 = (P[P_34][b3] & 0xFF) ^ b3(k3);
      case 3:
         b0 = (P[P_03][b0] & 0xFF) ^ b0(k2);
         b1 = (P[P_13][b1] & 0xFF) ^ b1(k2);
         b2 = (P[P_23][b2] & 0xFF) ^ b2(k2);
         b3 = (P[P_33][b3] & 0xFF) ^ b3(k2);
      case 2:                             // 128-bit keys (optimize for this case)
         result =
            MDS[0][(P[P_01][(P[P_02][b0] & 0xFF) ^ b0(k1)] & 0xFF) ^ b0(k0)] ^
            MDS[1][(P[P_11][(P[P_12][b1] & 0xFF) ^ b1(k1)] & 0xFF) ^ b1(k0)] ^
            MDS[2][(P[P_21][(P[P_22][b2] & 0xFF) ^ b2(k1)] & 0xFF) ^ b2(k0)] ^
            MDS[3][(P[P_31][(P[P_32][b3] & 0xFF) ^ b3(k1)] & 0xFF) ^ b3(k0)];
         break;
      }
      return result;
   }

   private static final int Fe32( int[] sBox, int x, int R ) {
      return sBox[        2*_b(x, R  )    ] ^
             sBox[        2*_b(x, R+1) + 1] ^
             sBox[0x200 + 2*_b(x, R+2)    ] ^
             sBox[0x200 + 2*_b(x, R+3) + 1];
   }

   private static final int _b( int x, int N) {
      int result = 0;
      switch (N%4) {
      case 0: result = b0(x); break;
      case 1: result = b1(x); break;
      case 2: result = b2(x); break;
      case 3: result = b3(x); break;
      }
      return result;
   }
   
   /** @return The length in bytes of the Algorithm input block. */
   public static int blockSize() { return BLOCK_SIZE; }

   /** A basic symmetric encryption/decryption test for a given key size. */
   private static boolean self_test (int keysize) {
if (DEBUG) trace(IN, "self_test("+keysize+")");
      boolean ok = false;
      try {
         byte[] kb = new byte[keysize];
         byte[] pt = new byte[BLOCK_SIZE];
         int i;

         for (i = 0; i < keysize; i++)
            kb[i] = (byte) i;
         for (i = 0; i < BLOCK_SIZE; i++)
            pt[i] = (byte) i;

if (DEBUG && debuglevel > 6) {
System.out.println("==========");
System.out.println();
System.out.println("KEYSIZE="+(8*keysize));
System.out.println("KEY="+toString(kb));
System.out.println();
}
         Object key = makeKey(kb);

if (DEBUG && debuglevel > 6) {
System.out.println("Intermediate Ciphertext Values (Encryption)");
System.out.println();
}
         byte[] ct = blockEncrypt(pt, 0, key);

if (DEBUG && debuglevel > 6) {
System.out.println("Intermediate Plaintext Values (Decryption)");
System.out.println();
}
         byte[] cpt = blockDecrypt(ct, 0, key);

         ok = areEqual(pt, cpt);
         if (!ok)
            throw new RuntimeException("Symmetric operation failed");
      } catch (Exception x) {
if (DEBUG && debuglevel > 0) {
   debug("Exception encountered during self-test: " + x.getMessage());
   x.printStackTrace();
}
      }
if (DEBUG && debuglevel > 0) debug("Self-test OK? " + ok);
if (DEBUG) trace(OUT, "self_test()");
      return ok;
   }


// utility static methods (from cryptix.util.core ArrayUtil and Hex classes)
//...........................................................................
   
   /** @return True iff the arrays have identical contents. */
   private static boolean areEqual (byte[] a, byte[] b) {
      int aLength = a.length;
      if (aLength != b.length)
         return false;
      for (int i = 0; i < aLength; i++)
         if (a[i] != b[i])
            return false;
      return true;
   }

   /**
    * Returns a string of 8 hexadecimal digits (most significant
    * digit first) corresponding to the integer <i>n</i>, which is
    * treated as unsigned.
    */
   private static String intToString (int n) {
      char[] buf = new char[8];
      for (int i = 7; i >= 0; i--) {
         buf[i] = HEX_DIGITS[n & 0x0F];
         n >>>= 4;
      }
      return new String(buf);
   }

   /**
    * Returns a string of hexadecimal digits from a byte array. Each
    * byte is converted to 2 hex symbols.
    */
   private static String toString (byte[] ba) {
      return toString(ba, 0, ba.length);
   }
   private static String toString (byte[] ba, int offset, int length) {
      char[] buf = new char[length * 2];
      for (int i = offset, j = 0, k; i < offset+length; ) {
         k = ba[i++];
         buf[j++] = HEX_DIGITS[(k >>> 4) & 0x0F];
         buf[j++] = HEX_DIGITS[ k      & 0x0F];
      }
      return new String(buf);
   }


// main(): use to generate the Intermediate Values KAT
//...........................................................................

   public static void main (String[] args) {
      self_test(16);
      self_test(24);
      self_test(32);
   }
}
