source: trunk/packages/sipb-xen-vnc-client/code/DesCipher.java @ 1162

//
// This DES class has been extracted from package Acme.Crypto for use in VNC.
// The bytebit[] array has been reversed so that the most significant bit
// in each byte of the key is ignored, not the least significant.  Also the
// unnecessary odd parity code has been removed.
//
// These changes are:
//  Copyright (C) 1999 AT&T Laboratories Cambridge.  All Rights Reserved.
//
// This software is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
//

// DesCipher - the DES encryption method
//
// The meat of this code is by Dave Zimmerman <dzimm@widget.com>, and is:
//
// Copyright (c) 1996 Widget Workshop, Inc. All Rights Reserved.
//
// Permission to use, copy, modify, and distribute this software
// and its documentation for NON-COMMERCIAL or COMMERCIAL purposes and
// without fee is hereby granted, provided that this copyright notice is kept 
// intact. 
// 
// WIDGET WORKSHOP MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY
// OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
// TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE, OR NON-INFRINGEMENT. WIDGET WORKSHOP SHALL NOT BE LIABLE
// FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
// DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
// 
// THIS SOFTWARE IS NOT DESIGNED OR INTENDED FOR USE OR RESALE AS ON-LINE
// CONTROL EQUIPMENT IN HAZARDOUS ENVIRONMENTS REQUIRING FAIL-SAFE
// PERFORMANCE, SUCH AS IN THE OPERATION OF NUCLEAR FACILITIES, AIRCRAFT
// NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL, DIRECT LIFE
// SUPPORT MACHINES, OR WEAPONS SYSTEMS, IN WHICH THE FAILURE OF THE
// SOFTWARE COULD LEAD DIRECTLY TO DEATH, PERSONAL INJURY, OR SEVERE
// PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH RISK ACTIVITIES").  WIDGET WORKSHOP
// SPECIFICALLY DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR
// HIGH RISK ACTIVITIES.
//
//
// The rest is:
//
// Copyright (C) 1996 by Jef Poskanzer <jef@acme.com>.  All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/


import java.io.*;

/// The DES encryption method.
// <P>
// This is surprisingly fast, for pure Java.  On a SPARC 20, wrapped
// in Acme.Crypto.EncryptedOutputStream or Acme.Crypto.EncryptedInputStream,
// it does around 7000 bytes/second.
// <P>
// Most of this code is by Dave Zimmerman <dzimm@widget.com>, and is
// Copyright (c) 1996 Widget Workshop, Inc.  See the source file for details.
// <P>
// <A HREF="/resources/classes/Acme/Crypto/DesCipher.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.Z">Fetch the entire Acme package.</A>
// <P>
// @see Des3Cipher
// @see EncryptedOutputStream
// @see EncryptedInputStream

public class DesCipher
    {

    // Constructor, byte-array key.
    public DesCipher( byte[] key )
        {
        setKey( key );
        }

    // Key routines.

    private int[] encryptKeys = new int[32];
    private int[] decryptKeys = new int[32];

    /// Set the key.
    public void setKey( byte[] key )
        {
        deskey( key, true, encryptKeys );
        deskey( key, false, decryptKeys );
        }

    // Turn an 8-byte key into internal keys.
    private void deskey( byte[] keyBlock, boolean encrypting, int[] KnL )
        {
        int i, j, l, m, n;
        int[] pc1m = new int[56];
        int[] pcr = new int[56];
        int[] kn = new int[32];

        for ( j = 0; j < 56; ++j )
            {
            l = pc1[j];
            m = l & 07;
            pc1m[j] = ( (keyBlock[l >>> 3] & bytebit[m]) != 0 )? 1: 0;
            }

        for ( i = 0; i < 16; ++i )
            {
            if ( encrypting )
                m = i << 1;
            else
                m = (15-i) << 1;
            n = m+1;
            kn[m] = kn[n] = 0;
            for ( j = 0; j < 28; ++j )
                {
                l = j+totrot[i];
                if ( l < 28 )
                    pcr[j] = pc1m[l];
                else
                    pcr[j] = pc1m[l-28];
                }
            for ( j=28; j < 56; ++j )
                {
                l = j+totrot[i];
                if ( l < 56 )
                    pcr[j] = pc1m[l];
                else
                    pcr[j] = pc1m[l-28];
                }
            for ( j = 0; j < 24; ++j )
                {
                if ( pcr[pc2[j]] != 0 )
                    kn[m] |= bigbyte[j];
                if ( pcr[pc2[j+24]] != 0 )
                    kn[n] |= bigbyte[j];
                }
            }
        cookey( kn, KnL );
        }

    private void cookey( int[] raw, int KnL[] )
        {
        int raw0, raw1;
        int rawi, KnLi;
        int i;

        for ( i = 0, rawi = 0, KnLi = 0; i < 16; ++i )
            {
            raw0 = raw[rawi++];
            raw1 = raw[rawi++];
            KnL[KnLi]  = (raw0 & 0x00fc0000) <<   6;
            KnL[KnLi] |= (raw0 & 0x00000fc0) <<  10;
            KnL[KnLi] |= (raw1 & 0x00fc0000) >>> 10;
            KnL[KnLi] |= (raw1 & 0x00000fc0) >>>  6;
            ++KnLi;
            KnL[KnLi]  = (raw0 & 0x0003f000) <<  12;
            KnL[KnLi] |= (raw0 & 0x0000003f) <<  16;
            KnL[KnLi] |= (raw1 & 0x0003f000) >>>  4;
            KnL[KnLi] |= (raw1 & 0x0000003f);
            ++KnLi;
            }
        }


    // Block encryption routines.

    private int[] tempInts = new int[2];

    /// Encrypt a block of eight bytes.
    public void encrypt( byte[] clearText, int clearOff, byte[] cipherText, int cipherOff )
        {
        squashBytesToInts( clearText, clearOff, tempInts, 0, 2 );
        des( tempInts, tempInts, encryptKeys );
        spreadIntsToBytes( tempInts, 0, cipherText, cipherOff, 2 );
        }

    /// Decrypt a block of eight bytes.
    public void decrypt( byte[] cipherText, int cipherOff, byte[] clearText, int clearOff )
        {
        squashBytesToInts( cipherText, cipherOff, tempInts, 0, 2 );
        des( tempInts, tempInts, decryptKeys );
        spreadIntsToBytes( tempInts, 0, clearText, clearOff, 2 );
        }

    // The DES function.
    private void des( int[] inInts, int[] outInts, int[] keys )
        {
        int fval, work, right, leftt;
        int round;
        int keysi = 0;

        leftt = inInts[0];
        right = inInts[1];

        work   = ((leftt >>>  4) ^ right) & 0x0f0f0f0f;
        right ^= work;
        leftt ^= (work << 4);

        work   = ((leftt >>> 16) ^ right) & 0x0000ffff;
        right ^= work;
        leftt ^= (work << 16);

        work   = ((right >>>  2) ^ leftt) & 0x33333333;
        leftt ^= work;
        right ^= (work << 2);

        work   = ((right >>>  8) ^ leftt) & 0x00ff00ff;
        leftt ^= work;
        right ^= (work << 8);
        right  = (right << 1) | ((right >>> 31) & 1);

        work   = (leftt ^ right) & 0xaaaaaaaa;
        leftt ^= work;
        right ^= work;
        leftt  = (leftt << 1) | ((leftt >>> 31) & 1);

        for ( round = 0; round < 8; ++round )
            {
            work   = (right << 28) | (right >>> 4);
            work  ^= keys[keysi++];
            fval   = SP7[ work         & 0x0000003f ];
            fval  |= SP5[(work >>>  8) & 0x0000003f ];
            fval  |= SP3[(work >>> 16) & 0x0000003f ];
            fval  |= SP1[(work >>> 24) & 0x0000003f ];
            work   = right ^ keys[keysi++];
            fval  |= SP8[ work         & 0x0000003f ];
            fval  |= SP6[(work >>>  8) & 0x0000003f ];
            fval  |= SP4[(work >>> 16) & 0x0000003f ];
            fval  |= SP2[(work >>> 24) & 0x0000003f ];
            leftt ^= fval;
            work   = (leftt << 28) | (leftt >>> 4);
            work  ^= keys[keysi++];
            fval   = SP7[ work         & 0x0000003f ];
            fval  |= SP5[(work >>>  8) & 0x0000003f ];
            fval  |= SP3[(work >>> 16) & 0x0000003f ];
            fval  |= SP1[(work >>> 24) & 0x0000003f ];
            work   = leftt ^ keys[keysi++];
            fval  |= SP8[ work         & 0x0000003f ];
            fval  |= SP6[(work >>>  8) & 0x0000003f ];
            fval  |= SP4[(work >>> 16) & 0x0000003f ];
            fval  |= SP2[(work >>> 24) & 0x0000003f ];
            right ^= fval;
            }

        right  = (right << 31) | (right >>> 1);
        work   = (leftt ^ right) & 0xaaaaaaaa;
        leftt ^= work;
        right ^= work;
        leftt  = (leftt << 31) | (leftt >>> 1);
        work   = ((leftt >>>  8) ^ right) & 0x00ff00ff;
        right ^= work;
        leftt ^= (work << 8);
        work   = ((leftt >>>  2) ^ right) & 0x33333333;
        right ^= work;
        leftt ^= (work << 2);
        work   = ((right >>> 16) ^ leftt) & 0x0000ffff;
        leftt ^= work;
        right ^= (work << 16);
        work   = ((right >>>  4) ^ leftt) & 0x0f0f0f0f;
        leftt ^= work;
        right ^= (work << 4);
        outInts[0] = right;
        outInts[1] = leftt;
        }


    // Tables, permutations, S-boxes, etc.

    private static byte[] bytebit = {
        (byte)0x01, (byte)0x02, (byte)0x04, (byte)0x08,
        (byte)0x10, (byte)0x20, (byte)0x40, (byte)0x80
        };
    private static int[] bigbyte = {
        0x800000, 0x400000, 0x200000, 0x100000,
        0x080000, 0x040000, 0x020000, 0x010000,
        0x008000, 0x004000, 0x002000, 0x001000,
        0x000800, 0x000400, 0x000200, 0x000100,
        0x000080, 0x000040, 0x000020, 0x000010,
        0x000008, 0x000004, 0x000002, 0x000001
        };
    private static byte[] pc1 = {
         (byte)56, (byte)48, (byte)40, (byte)32, (byte)24, (byte)16, (byte) 8,
      (byte) 0, (byte)57, (byte)49, (byte)41, (byte)33, (byte)25, (byte)17,
         (byte) 9, (byte) 1, (byte)58, (byte)50, (byte)42, (byte)34, (byte)26,
      (byte)18, (byte)10, (byte) 2, (byte)59, (byte)51, (byte)43, (byte)35,
         (byte)62, (byte)54, (byte)46, (byte)38, (byte)30, (byte)22, (byte)14,
      (byte) 6, (byte)61, (byte)53, (byte)45, (byte)37, (byte)29, (byte)21,
         (byte)13, (byte) 5, (byte)60, (byte)52, (byte)44, (byte)36, (byte)28,
      (byte)20, (byte)12, (byte) 4, (byte)27, (byte)19, (byte)11, (byte)3
        };
    private static int[] totrot = {
        1, 2, 4, 6, 8, 10, 12, 14, 15, 17, 19, 21, 23, 25, 27, 28
        };

    private static byte[] pc2 = {
        (byte)13, (byte)16, (byte)10, (byte)23, (byte) 0, (byte) 4,
                  (byte) 2, (byte)27, (byte)14, (byte) 5, (byte)20, (byte) 9,
        (byte)22, (byte)18, (byte)11, (byte)3 , (byte)25, (byte) 7,
                  (byte)15, (byte) 6, (byte)26, (byte)19, (byte)12, (byte) 1,
        (byte)40, (byte)51, (byte)30, (byte)36, (byte)46, (byte)54,
                  (byte)29, (byte)39, (byte)50, (byte)44, (byte)32, (byte)47,
        (byte)43, (byte)48, (byte)38, (byte)55, (byte)33, (byte)52,
                  (byte)45, (byte)41, (byte)49, (byte)35, (byte)28, (byte)31,
        };

    private static int[] SP1 = {
        0x01010400, 0x00000000, 0x00010000, 0x01010404,
        0x01010004, 0x00010404, 0x00000004, 0x00010000,
        0x00000400, 0x01010400, 0x01010404, 0x00000400,
        0x01000404, 0x01010004, 0x01000000, 0x00000004,
        0x00000404, 0x01000400, 0x01000400, 0x00010400,
        0x00010400, 0x01010000, 0x01010000, 0x01000404,
        0x00010004, 0x01000004, 0x01000004, 0x00010004,
        0x00000000, 0x00000404, 0x00010404, 0x01000000,
        0x00010000, 0x01010404, 0x00000004, 0x01010000,
        0x01010400, 0x01000000, 0x01000000, 0x00000400,
        0x01010004, 0x00010000, 0x00010400, 0x01000004,
        0x00000400, 0x00000004, 0x01000404, 0x00010404,
        0x01010404, 0x00010004, 0x01010000, 0x01000404,
        0x01000004, 0x00000404, 0x00010404, 0x01010400,
        0x00000404, 0x01000400, 0x01000400, 0x00000000,
        0x00010004, 0x00010400, 0x00000000, 0x01010004
        };
    private static int[] SP2 = {
        0x80108020, 0x80008000, 0x00008000, 0x00108020,
        0x00100000, 0x00000020, 0x80100020, 0x80008020,
        0x80000020, 0x80108020, 0x80108000, 0x80000000,
        0x80008000, 0x00100000, 0x00000020, 0x80100020,
        0x00108000, 0x00100020, 0x80008020, 0x00000000,
        0x80000000, 0x00008000, 0x00108020, 0x80100000,
        0x00100020, 0x80000020, 0x00000000, 0x00108000,
        0x00008020, 0x80108000, 0x80100000, 0x00008020,
        0x00000000, 0x00108020, 0x80100020, 0x00100000,
        0x80008020, 0x80100000, 0x80108000, 0x00008000,
        0x80100000, 0x80008000, 0x00000020, 0x80108020,
        0x00108020, 0x00000020, 0x00008000, 0x80000000,
        0x00008020, 0x80108000, 0x00100000, 0x80000020,
        0x00100020, 0x80008020, 0x80000020, 0x00100020,
        0x00108000, 0x00000000, 0x80008000, 0x00008020,
        0x80000000, 0x80100020, 0x80108020, 0x00108000
        };
    private static int[] SP3 = {
        0x00000208, 0x08020200, 0x00000000, 0x08020008,
        0x08000200, 0x00000000, 0x00020208, 0x08000200,
        0x00020008, 0x08000008, 0x08000008, 0x00020000,
        0x08020208, 0x00020008, 0x08020000, 0x00000208,
        0x08000000, 0x00000008, 0x08020200, 0x00000200,
        0x00020200, 0x08020000, 0x08020008, 0x00020208,
        0x08000208, 0x00020200, 0x00020000, 0x08000208,
        0x00000008, 0x08020208, 0x00000200, 0x08000000,
        0x08020200, 0x08000000, 0x00020008, 0x00000208,
        0x00020000, 0x08020200, 0x08000200, 0x00000000,
        0x00000200, 0x00020008, 0x08020208, 0x08000200,
        0x08000008, 0x00000200, 0x00000000, 0x08020008,
        0x08000208, 0x00020000, 0x08000000, 0x08020208,
        0x00000008, 0x00020208, 0x00020200, 0x08000008,
        0x08020000, 0x08000208, 0x00000208, 0x08020000,
        0x00020208, 0x00000008, 0x08020008, 0x00020200
        };
    private static int[] SP4 = {
        0x00802001, 0x00002081, 0x00002081, 0x00000080,
        0x00802080, 0x00800081, 0x00800001, 0x00002001,
        0x00000000, 0x00802000, 0x00802000, 0x00802081,
        0x00000081, 0x00000000, 0x00800080, 0x00800001,
        0x00000001, 0x00002000, 0x00800000, 0x00802001,
        0x00000080, 0x00800000, 0x00002001, 0x00002080,
        0x00800081, 0x00000001, 0x00002080, 0x00800080,
        0x00002000, 0x00802080, 0x00802081, 0x00000081,
        0x00800080, 0x00800001, 0x00802000, 0x00802081,
        0x00000081, 0x00000000, 0x00000000, 0x00802000,
        0x00002080, 0x00800080, 0x00800081, 0x00000001,
        0x00802001, 0x00002081, 0x00002081, 0x00000080,
        0x00802081, 0x00000081, 0x00000001, 0x00002000,
        0x00800001, 0x00002001, 0x00802080, 0x00800081,
        0x00002001, 0x00002080, 0x00800000, 0x00802001,
        0x00000080, 0x00800000, 0x00002000, 0x00802080
        };
    private static int[] SP5 = {
        0x00000100, 0x02080100, 0x02080000, 0x42000100,
        0x00080000, 0x00000100, 0x40000000, 0x02080000,
        0x40080100, 0x00080000, 0x02000100, 0x40080100,
        0x42000100, 0x42080000, 0x00080100, 0x40000000,
        0x02000000, 0x40080000, 0x40080000, 0x00000000,
        0x40000100, 0x42080100, 0x42080100, 0x02000100,
        0x42080000, 0x40000100, 0x00000000, 0x42000000,
        0x02080100, 0x02000000, 0x42000000, 0x00080100,
        0x00080000, 0x42000100, 0x00000100, 0x02000000,
        0x40000000, 0x02080000, 0x42000100, 0x40080100,
        0x02000100, 0x40000000, 0x42080000, 0x02080100,
        0x40080100, 0x00000100, 0x02000000, 0x42080000,
        0x42080100, 0x00080100, 0x42000000, 0x42080100,
        0x02080000, 0x00000000, 0x40080000, 0x42000000,
        0x00080100, 0x02000100, 0x40000100, 0x00080000,
        0x00000000, 0x40080000, 0x02080100, 0x40000100
        };
    private static int[] SP6 = {
        0x20000010, 0x20400000, 0x00004000, 0x20404010,
        0x20400000, 0x00000010, 0x20404010, 0x00400000,
        0x20004000, 0x00404010, 0x00400000, 0x20000010,
        0x00400010, 0x20004000, 0x20000000, 0x00004010,
        0x00000000, 0x00400010, 0x20004010, 0x00004000,
        0x00404000, 0x20004010, 0x00000010, 0x20400010,
        0x20400010, 0x00000000, 0x00404010, 0x20404000,
        0x00004010, 0x00404000, 0x20404000, 0x20000000,
        0x20004000, 0x00000010, 0x20400010, 0x00404000,
        0x20404010, 0x00400000, 0x00004010, 0x20000010,
        0x00400000, 0x20004000, 0x20000000, 0x00004010,
        0x20000010, 0x20404010, 0x00404000, 0x20400000,
        0x00404010, 0x20404000, 0x00000000, 0x20400010,
        0x00000010, 0x00004000, 0x20400000, 0x00404010,
        0x00004000, 0x00400010, 0x20004010, 0x00000000,
        0x20404000, 0x20000000, 0x00400010, 0x20004010
        };
    private static int[] SP7 = {
        0x00200000, 0x04200002, 0x04000802, 0x00000000,
        0x00000800, 0x04000802, 0x00200802, 0x04200800,
        0x04200802, 0x00200000, 0x00000000, 0x04000002,
        0x00000002, 0x04000000, 0x04200002, 0x00000802,
        0x04000800, 0x00200802, 0x00200002, 0x04000800,
        0x04000002, 0x04200000, 0x04200800, 0x00200002,
        0x04200000, 0x00000800, 0x00000802, 0x04200802,
        0x00200800, 0x00000002, 0x04000000, 0x00200800,
        0x04000000, 0x00200800, 0x00200000, 0x04000802,
        0x04000802, 0x04200002, 0x04200002, 0x00000002,
        0x00200002, 0x04000000, 0x04000800, 0x00200000,
        0x04200800, 0x00000802, 0x00200802, 0x04200800,
        0x00000802, 0x04000002, 0x04200802, 0x04200000,
        0x00200800, 0x00000000, 0x00000002, 0x04200802,
        0x00000000, 0x00200802, 0x04200000, 0x00000800,
        0x04000002, 0x04000800, 0x00000800, 0x00200002
        };
    private static int[] SP8 = {
        0x10001040, 0x00001000, 0x00040000, 0x10041040,
        0x10000000, 0x10001040, 0x00000040, 0x10000000,
        0x00040040, 0x10040000, 0x10041040, 0x00041000,
        0x10041000, 0x00041040, 0x00001000, 0x00000040,
        0x10040000, 0x10000040, 0x10001000, 0x00001040,
        0x00041000, 0x00040040, 0x10040040, 0x10041000,
        0x00001040, 0x00000000, 0x00000000, 0x10040040,
        0x10000040, 0x10001000, 0x00041040, 0x00040000,
        0x00041040, 0x00040000, 0x10041000, 0x00001000,
        0x00000040, 0x10040040, 0x00001000, 0x00041040,
        0x10001000, 0x00000040, 0x10000040, 0x10040000,
        0x10040040, 0x10000000, 0x00040000, 0x10001040,
        0x00000000, 0x10041040, 0x00040040, 0x10000040,
        0x10040000, 0x10001000, 0x10001040, 0x00000000,
        0x10041040, 0x00041000, 0x00041000, 0x00001040,
        0x00001040, 0x00040040, 0x10000000, 0x10041000
        };

    // Routines taken from other parts of the Acme utilities.

    /// Squash bytes down to ints.
    public static void squashBytesToInts( byte[] inBytes, int inOff, int[] outInts, int outOff, int intLen )
        {
        for ( int i = 0; i < intLen; ++i )
            outInts[outOff + i] = 
                ( ( inBytes[inOff + i * 4    ] & 0xff ) << 24 ) |
                ( ( inBytes[inOff + i * 4 + 1] & 0xff ) << 16 ) |
                ( ( inBytes[inOff + i * 4 + 2] & 0xff ) <<  8 ) |
                  ( inBytes[inOff + i * 4 + 3] & 0xff );
        }

    /// Spread ints into bytes.
    public static void spreadIntsToBytes( int[] inInts, int inOff, byte[] outBytes, int outOff, int intLen )
        {
        for ( int i = 0; i < intLen; ++i )
            {
            outBytes[outOff + i * 4    ] = (byte) ( inInts[inOff + i] >>> 24 );
            outBytes[outOff + i * 4 + 1] = (byte) ( inInts[inOff + i] >>> 16 );
            outBytes[outOff + i * 4 + 2] = (byte) ( inInts[inOff + i] >>>  8 );
            outBytes[outOff + i * 4 + 3] = (byte)   inInts[inOff + i];
            }
        }
    }