/*
 * This file is part of ***  M y C o R e  ***
 * See http://www.mycore.de/ for details.
 *
 * MyCoRe is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * MyCoRe 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with MyCoRe.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.mycore.common;

/**
 * Java-based implementation of the unix crypt(3) command
 *
 * Based upon C source code written by Eric Young, eay@psych.uq.oz.au Java
 * conversion by John F. Dumas, jdumas@zgs.com
 *
 * Found at
 * <a href="http://locutus.kingwoodcable.com/jfd/crypt.html">http://locutus.kingwoodcable.com/jfd/crypt.html</a>
 * Minor optimizations by Wes Biggs, wes@cacas.org Adaption and extension for the MyCoRe Open Source
 * System by Detlev Degenhardt, Detlev.Degenhardt@rz.uni-freiburg.de
 *
 * Eric's original code is licensed under the BSD license. As this is
 * derivative, the same license applies.
 *
 * @author Detlev Degenhardt
 */
public class MCRCrypt {

    private static final int ITERATIONS = 16;

    private static final boolean[] SHIFTS_2 = { false, false, true, true, true, true, true, true, false, true, true,
        true, true, true, true,
        false };

    private static final int[][] SKB = {
        {

            /* for C bits (numbered as per FIPS 46) 1 2 3 4 5 6 */
            0x00000000, 0x00000010, 0x20000000, 0x20000010, 0x00010000, 0x00010010, 0x20010000, 0x20010010, 0x00000800,
            0x00000810,
            0x20000800, 0x20000810, 0x00010800, 0x00010810, 0x20010800, 0x20010810, 0x00000020, 0x00000030, 0x20000020,
            0x20000030,
            0x00010020, 0x00010030, 0x20010020, 0x20010030, 0x00000820, 0x00000830, 0x20000820, 0x20000830, 0x00010820,
            0x00010830,
            0x20010820, 0x20010830, 0x00080000, 0x00080010, 0x20080000, 0x20080010, 0x00090000, 0x00090010, 0x20090000,
            0x20090010,
            0x00080800, 0x00080810, 0x20080800, 0x20080810, 0x00090800, 0x00090810, 0x20090800, 0x20090810, 0x00080020,
            0x00080030,
            0x20080020, 0x20080030, 0x00090020, 0x00090030, 0x20090020, 0x20090030, 0x00080820, 0x00080830, 0x20080820,
            0x20080830,
            0x00090820, 0x00090830, 0x20090820, 0x20090830, },
        {

            /* for C bits (numbered as per FIPS 46) 7 8 10 11 12 13 */
            0x00000000, 0x02000000, 0x00002000, 0x02002000, 0x00200000, 0x02200000, 0x00202000, 0x02202000, 0x00000004,
            0x02000004,
            0x00002004, 0x02002004, 0x00200004, 0x02200004, 0x00202004, 0x02202004, 0x00000400, 0x02000400, 0x00002400,
            0x02002400,
            0x00200400, 0x02200400, 0x00202400, 0x02202400, 0x00000404, 0x02000404, 0x00002404, 0x02002404, 0x00200404,
            0x02200404,
            0x00202404, 0x02202404, 0x10000000, 0x12000000, 0x10002000, 0x12002000, 0x10200000, 0x12200000, 0x10202000,
            0x12202000,
            0x10000004, 0x12000004, 0x10002004, 0x12002004, 0x10200004, 0x12200004, 0x10202004, 0x12202004, 0x10000400,
            0x12000400,
            0x10002400, 0x12002400, 0x10200400, 0x12200400, 0x10202400, 0x12202400, 0x10000404, 0x12000404, 0x10002404,
            0x12002404,
            0x10200404, 0x12200404, 0x10202404, 0x12202404, },
        {

            /* for C bits (numbered as per FIPS 46) 14 15 16 17 19 20 */
            0x00000000, 0x00000001, 0x00040000, 0x00040001, 0x01000000, 0x01000001, 0x01040000, 0x01040001, 0x00000002,
            0x00000003,
            0x00040002, 0x00040003, 0x01000002, 0x01000003, 0x01040002, 0x01040003, 0x00000200, 0x00000201, 0x00040200,
            0x00040201,
            0x01000200, 0x01000201, 0x01040200, 0x01040201, 0x00000202, 0x00000203, 0x00040202, 0x00040203, 0x01000202,
            0x01000203,
            0x01040202, 0x01040203, 0x08000000, 0x08000001, 0x08040000, 0x08040001, 0x09000000, 0x09000001, 0x09040000,
            0x09040001,
            0x08000002, 0x08000003, 0x08040002, 0x08040003, 0x09000002, 0x09000003, 0x09040002, 0x09040003, 0x08000200,
            0x08000201,
            0x08040200, 0x08040201, 0x09000200, 0x09000201, 0x09040200, 0x09040201, 0x08000202, 0x08000203, 0x08040202,
            0x08040203,
            0x09000202, 0x09000203, 0x09040202, 0x09040203, },
        {

            /* for C bits (numbered as per FIPS 46) 21 23 24 26 27 28 */
            0x00000000, 0x00100000, 0x00000100, 0x00100100, 0x00000008, 0x00100008, 0x00000108, 0x00100108, 0x00001000,
            0x00101000,
            0x00001100, 0x00101100, 0x00001008, 0x00101008, 0x00001108, 0x00101108, 0x04000000, 0x04100000, 0x04000100,
            0x04100100,
            0x04000008, 0x04100008, 0x04000108, 0x04100108, 0x04001000, 0x04101000, 0x04001100, 0x04101100, 0x04001008,
            0x04101008,
            0x04001108, 0x04101108, 0x00020000, 0x00120000, 0x00020100, 0x00120100, 0x00020008, 0x00120008, 0x00020108,
            0x00120108,
            0x00021000, 0x00121000, 0x00021100, 0x00121100, 0x00021008, 0x00121008, 0x00021108, 0x00121108, 0x04020000,
            0x04120000,
            0x04020100, 0x04120100, 0x04020008, 0x04120008, 0x04020108, 0x04120108, 0x04021000, 0x04121000, 0x04021100,
            0x04121100,
            0x04021008, 0x04121008, 0x04021108, 0x04121108, },
        {

            /* for D bits (numbered as per FIPS 46) 1 2 3 4 5 6 */
            0x00000000, 0x10000000, 0x00010000, 0x10010000, 0x00000004, 0x10000004, 0x00010004, 0x10010004, 0x20000000,
            0x30000000,
            0x20010000, 0x30010000, 0x20000004, 0x30000004, 0x20010004, 0x30010004, 0x00100000, 0x10100000, 0x00110000,
            0x10110000,
            0x00100004, 0x10100004, 0x00110004, 0x10110004, 0x20100000, 0x30100000, 0x20110000, 0x30110000, 0x20100004,
            0x30100004,
            0x20110004, 0x30110004, 0x00001000, 0x10001000, 0x00011000, 0x10011000, 0x00001004, 0x10001004, 0x00011004,
            0x10011004,
            0x20001000, 0x30001000, 0x20011000, 0x30011000, 0x20001004, 0x30001004, 0x20011004, 0x30011004, 0x00101000,
            0x10101000,
            0x00111000, 0x10111000, 0x00101004, 0x10101004, 0x00111004, 0x10111004, 0x20101000, 0x30101000, 0x20111000,
            0x30111000,
            0x20101004, 0x30101004, 0x20111004, 0x30111004, },
        {

            /* for D bits (numbered as per FIPS 46) 8 9 11 12 13 14 */
            0x00000000, 0x08000000, 0x00000008, 0x08000008, 0x00000400, 0x08000400, 0x00000408, 0x08000408, 0x00020000,
            0x08020000,
            0x00020008, 0x08020008, 0x00020400, 0x08020400, 0x00020408, 0x08020408, 0x00000001, 0x08000001, 0x00000009,
            0x08000009,
            0x00000401, 0x08000401, 0x00000409, 0x08000409, 0x00020001, 0x08020001, 0x00020009, 0x08020009, 0x00020401,
            0x08020401,
            0x00020409, 0x08020409, 0x02000000, 0x0A000000, 0x02000008, 0x0A000008, 0x02000400, 0x0A000400, 0x02000408,
            0x0A000408,
            0x02020000, 0x0A020000, 0x02020008, 0x0A020008, 0x02020400, 0x0A020400, 0x02020408, 0x0A020408, 0x02000001,
            0x0A000001,
            0x02000009, 0x0A000009, 0x02000401, 0x0A000401, 0x02000409, 0x0A000409, 0x02020001, 0x0A020001, 0x02020009,
            0x0A020009,
            0x02020401, 0x0A020401, 0x02020409, 0x0A020409, },
        {

            /* for D bits (numbered as per FIPS 46) 16 17 18 19 20 21 */
            0x00000000, 0x00000100, 0x00080000, 0x00080100, 0x01000000, 0x01000100, 0x01080000, 0x01080100, 0x00000010,
            0x00000110,
            0x00080010, 0x00080110, 0x01000010, 0x01000110, 0x01080010, 0x01080110, 0x00200000, 0x00200100, 0x00280000,
            0x00280100,
            0x01200000, 0x01200100, 0x01280000, 0x01280100, 0x00200010, 0x00200110, 0x00280010, 0x00280110, 0x01200010,
            0x01200110,
            0x01280010, 0x01280110, 0x00000200, 0x00000300, 0x00080200, 0x00080300, 0x01000200, 0x01000300, 0x01080200,
            0x01080300,
            0x00000210, 0x00000310, 0x00080210, 0x00080310, 0x01000210, 0x01000310, 0x01080210, 0x01080310, 0x00200200,
            0x00200300,
            0x00280200, 0x00280300, 0x01200200, 0x01200300, 0x01280200, 0x01280300, 0x00200210, 0x00200310, 0x00280210,
            0x00280310,
            0x01200210, 0x01200310, 0x01280210, 0x01280310, },
        {

            /* for D bits (numbered as per FIPS 46) 22 23 24 25 27 28 */
            0x00000000, 0x04000000, 0x00040000, 0x04040000, 0x00000002, 0x04000002, 0x00040002, 0x04040002, 0x00002000,
            0x04002000,
            0x00042000, 0x04042000, 0x00002002, 0x04002002, 0x00042002, 0x04042002, 0x00000020, 0x04000020, 0x00040020,
            0x04040020,
            0x00000022, 0x04000022, 0x00040022, 0x04040022, 0x00002020, 0x04002020, 0x00042020, 0x04042020, 0x00002022,
            0x04002022,
            0x00042022, 0x04042022, 0x00000800, 0x04000800, 0x00040800, 0x04040800, 0x00000802, 0x04000802, 0x00040802,
            0x04040802,
            0x00002800, 0x04002800, 0x00042800, 0x04042800, 0x00002802, 0x04002802, 0x00042802, 0x04042802, 0x00000820,
            0x04000820,
            0x00040820, 0x04040820, 0x00000822, 0x04000822, 0x00040822, 0x04040822, 0x00002820, 0x04002820, 0x00042820,
            0x04042820,
            0x00002822, 0x04002822, 0x00042822, 0x04042822, }, };

    private static final int[][] SPTRANS = {
        {

            /* nibble 0 */
            0x00820200, 0x00020000, 0x80800000, 0x80820200, 0x00800000, 0x80020200, 0x80020000, 0x80800000, 0x80020200,
            0x00820200,
            0x00820000, 0x80000200, 0x80800200, 0x00800000, 0x00000000, 0x80020000, 0x00020000, 0x80000000, 0x00800200,
            0x00020200,
            0x80820200, 0x00820000, 0x80000200, 0x00800200, 0x80000000, 0x00000200, 0x00020200, 0x80820000, 0x00000200,
            0x80800200,
            0x80820000, 0x00000000, 0x00000000, 0x80820200, 0x00800200, 0x80020000, 0x00820200, 0x00020000, 0x80000200,
            0x00800200,
            0x80820000, 0x00000200, 0x00020200, 0x80800000, 0x80020200, 0x80000000, 0x80800000, 0x00820000, 0x80820200,
            0x00020200,
            0x00820000, 0x80800200, 0x00800000, 0x80000200, 0x80020000, 0x00000000, 0x00020000, 0x00800000, 0x80800200,
            0x00820200,
            0x80000000, 0x80820000, 0x00000200, 0x80020200, },
        {

            /* nibble 1 */
            0x10042004, 0x00000000, 0x00042000, 0x10040000, 0x10000004, 0x00002004, 0x10002000, 0x00042000, 0x00002000,
            0x10040004,
            0x00000004, 0x10002000, 0x00040004, 0x10042000, 0x10040000, 0x00000004, 0x00040000, 0x10002004, 0x10040004,
            0x00002000,
            0x00042004, 0x10000000, 0x00000000, 0x00040004, 0x10002004, 0x00042004, 0x10042000, 0x10000004, 0x10000000,
            0x00040000,
            0x00002004, 0x10042004, 0x00040004, 0x10042000, 0x10002000, 0x00042004, 0x10042004, 0x00040004, 0x10000004,
            0x00000000,
            0x10000000, 0x00002004, 0x00040000, 0x10040004, 0x00002000, 0x10000000, 0x00042004, 0x10002004, 0x10042000,
            0x00002000,
            0x00000000, 0x10000004, 0x00000004, 0x10042004, 0x00042000, 0x10040000, 0x10040004, 0x00040000, 0x00002004,
            0x10002000,
            0x10002004, 0x00000004, 0x10040000, 0x00042000, },
        {

            /* nibble 2 */
            0x41000000, 0x01010040, 0x00000040, 0x41000040, 0x40010000, 0x01000000, 0x41000040, 0x00010040, 0x01000040,
            0x00010000,
            0x01010000, 0x40000000, 0x41010040, 0x40000040, 0x40000000, 0x41010000, 0x00000000, 0x40010000, 0x01010040,
            0x00000040,
            0x40000040, 0x41010040, 0x00010000, 0x41000000, 0x41010000, 0x01000040, 0x40010040, 0x01010000, 0x00010040,
            0x00000000,
            0x01000000, 0x40010040, 0x01010040, 0x00000040, 0x40000000, 0x00010000, 0x40000040, 0x40010000, 0x01010000,
            0x41000040,
            0x00000000, 0x01010040, 0x00010040, 0x41010000, 0x40010000, 0x01000000, 0x41010040, 0x40000000, 0x40010040,
            0x41000000,
            0x01000000, 0x41010040, 0x00010000, 0x01000040, 0x41000040, 0x00010040, 0x01000040, 0x00000000, 0x41010000,
            0x40000040,
            0x41000000, 0x40010040, 0x00000040, 0x01010000, },
        {

            /* nibble 3 */
            0x00100402, 0x04000400, 0x00000002, 0x04100402, 0x00000000, 0x04100000, 0x04000402, 0x00100002, 0x04100400,
            0x04000002,
            0x04000000, 0x00000402, 0x04000002, 0x00100402, 0x00100000, 0x04000000, 0x04100002, 0x00100400, 0x00000400,
            0x00000002,
            0x00100400, 0x04000402, 0x04100000, 0x00000400, 0x00000402, 0x00000000, 0x00100002, 0x04100400, 0x04000400,
            0x04100002,
            0x04100402, 0x00100000, 0x04100002, 0x00000402, 0x00100000, 0x04000002, 0x00100400, 0x04000400, 0x00000002,
            0x04100000,
            0x04000402, 0x00000000, 0x00000400, 0x00100002, 0x00000000, 0x04100002, 0x04100400, 0x00000400, 0x04000000,
            0x04100402,
            0x00100402, 0x00100000, 0x04100402, 0x00000002, 0x04000400, 0x00100402, 0x00100002, 0x00100400, 0x04100000,
            0x04000402,
            0x00000402, 0x04000000, 0x04000002, 0x04100400, },
        {

            /* nibble 4 */
            0x02000000, 0x00004000, 0x00000100, 0x02004108, 0x02004008, 0x02000100, 0x00004108, 0x02004000, 0x00004000,
            0x00000008,
            0x02000008, 0x00004100, 0x02000108, 0x02004008, 0x02004100, 0x00000000, 0x00004100, 0x02000000, 0x00004008,
            0x00000108,
            0x02000100, 0x00004108, 0x00000000, 0x02000008, 0x00000008, 0x02000108, 0x02004108, 0x00004008, 0x02004000,
            0x00000100,
            0x00000108, 0x02004100, 0x02004100, 0x02000108, 0x00004008, 0x02004000, 0x00004000, 0x00000008, 0x02000008,
            0x02000100,
            0x02000000, 0x00004100, 0x02004108, 0x00000000, 0x00004108, 0x02000000, 0x00000100, 0x00004008, 0x02000108,
            0x00000100,
            0x00000000, 0x02004108, 0x02004008, 0x02004100, 0x00000108, 0x00004000, 0x00004100, 0x02004008, 0x02000100,
            0x00000108,
            0x00000008, 0x00004108, 0x02004000, 0x02000008, },
        {

            /* nibble 5 */
            0x20000010, 0x00080010, 0x00000000, 0x20080800, 0x00080010, 0x00000800, 0x20000810, 0x00080000, 0x00000810,
            0x20080810,
            0x00080800, 0x20000000, 0x20000800, 0x20000010, 0x20080000, 0x00080810, 0x00080000, 0x20000810, 0x20080010,
            0x00000000,
            0x00000800, 0x00000010, 0x20080800, 0x20080010, 0x20080810, 0x20080000, 0x20000000, 0x00000810, 0x00000010,
            0x00080800,
            0x00080810, 0x20000800, 0x00000810, 0x20000000, 0x20000800, 0x00080810, 0x20080800, 0x00080010, 0x00000000,
            0x20000800,
            0x20000000, 0x00000800, 0x20080010, 0x00080000, 0x00080010, 0x20080810, 0x00080800, 0x00000010, 0x20080810,
            0x00080800,
            0x00080000, 0x20000810, 0x20000010, 0x20080000, 0x00080810, 0x00000000, 0x00000800, 0x20000010, 0x20000810,
            0x20080800,
            0x20080000, 0x00000810, 0x00000010, 0x20080010, },
        {

            /* nibble 6 */
            0x00001000, 0x00000080, 0x00400080, 0x00400001, 0x00401081, 0x00001001, 0x00001080, 0x00000000, 0x00400000,
            0x00400081,
            0x00000081, 0x00401000, 0x00000001, 0x00401080, 0x00401000, 0x00000081, 0x00400081, 0x00001000, 0x00001001,
            0x00401081,
            0x00000000, 0x00400080, 0x00400001, 0x00001080, 0x00401001, 0x00001081, 0x00401080, 0x00000001, 0x00001081,
            0x00401001,
            0x00000080, 0x00400000, 0x00001081, 0x00401000, 0x00401001, 0x00000081, 0x00001000, 0x00000080, 0x00400000,
            0x00401001,
            0x00400081, 0x00001081, 0x00001080, 0x00000000, 0x00000080, 0x00400001, 0x00000001, 0x00400080, 0x00000000,
            0x00400081,
            0x00400080, 0x00001080, 0x00000081, 0x00001000, 0x00401081, 0x00400000, 0x00401080, 0x00000001, 0x00001001,
            0x00401081,
            0x00400001, 0x00401080, 0x00401000, 0x00001001, },
        {

            /* nibble 7 */
            0x08200020, 0x08208000, 0x00008020, 0x00000000, 0x08008000, 0x00200020, 0x08200000, 0x08208020, 0x00000020,
            0x08000000,
            0x00208000, 0x00008020, 0x00208020, 0x08008020, 0x08000020, 0x08200000, 0x00008000, 0x00208020, 0x00200020,
            0x08008000,
            0x08208020, 0x08000020, 0x00000000, 0x00208000, 0x08000000, 0x00200000, 0x08008020, 0x08200020, 0x00200000,
            0x00008000,
            0x08208000, 0x00000020, 0x00200000, 0x00008000, 0x08000020, 0x08208020, 0x00008020, 0x08000000, 0x00000000,
            0x00208000,
            0x08200020, 0x08008020, 0x08008000, 0x00200020, 0x08208000, 0x00000020, 0x00200020, 0x08008000, 0x08208020,
            0x00200000,
            0x08200000, 0x08000020, 0x00208000, 0x00008020, 0x08008020, 0x08200000, 0x00000020, 0x08208000, 0x00208020,
            0x00000000,
            0x08000000, 0x08200020, 0x00008000, 0x00208020, }, };

    private MCRCrypt() {
    } // defined so class can't be instantiated.

    private static int byteToUnsigned(byte b) {
        return b >= 0 ? (int) b : b + 256;
    }

    private static int fourBytesToInt(byte[] b, int offset) {
        return byteToUnsigned(b[offset++]) | byteToUnsigned(b[offset++]) << 8 | byteToUnsigned(b[offset++]) << 16
            | byteToUnsigned(b[offset]) << 24;
    }

    private static void intToFourBytes(int iValue, byte[] b, int offset) {
        b[offset++] = (byte) (iValue & 0xff);
        b[offset++] = (byte) (iValue >>> 8 & 0xff);
        b[offset++] = (byte) (iValue >>> 16 & 0xff);
        b[offset] = (byte) (iValue >>> 24 & 0xff);
    }

    private static void permOp(int a, int b, int n, int m, int[] results) {
        int t;

        t = (a >>> n ^ b) & m;
        a ^= t << n;
        b ^= t;

        results[0] = a;
        results[1] = b;
    }

    private static int hpermOp(int a, int n, int m) {
        int t;

        t = (a << 16 - n ^ a) & m;
        a = a ^ t ^ t >>> 16 - n;

        return a;
    }

    private static int[] desSetKey(byte[] key) {
        int[] schedule = new int[ITERATIONS * 2];

        int c = fourBytesToInt(key, 0);
        int d = fourBytesToInt(key, 4);

        int[] results = new int[2];

        permOp(d, c, 4, 0x0f0f0f0f, results);
        d = results[0];
        c = results[1];

        c = hpermOp(c, -2, 0xcccc0000);
        d = hpermOp(d, -2, 0xcccc0000);

        permOp(d, c, 1, 0x55555555, results);
        d = results[0];
        c = results[1];

        permOp(c, d, 8, 0x00ff00ff, results);
        c = results[0];
        d = results[1];

        permOp(d, c, 1, 0x55555555, results);
        d = results[0];
        c = results[1];

        d = (d & 0x000000ff) << 16 | d & 0x0000ff00 | (d & 0x00ff0000) >>> 16 | (c & 0xf0000000) >>> 4;
        c &= 0x0fffffff;

        int s;
        int t;
        int j = 0;

        for (int i = 0; i < ITERATIONS; i++) {
            if (SHIFTS_2[i]) {
                c = c >>> 2 | c << 26;
                d = d >>> 2 | d << 26;
            } else {
                c = c >>> 1 | c << 27;
                d = d >>> 1 | d << 27;
            }

            c &= 0x0fffffff;
            d &= 0x0fffffff;

            s = SKB[0][c & 0x3f] | SKB[1][c >>> 6 & 0x03 | c >>> 7 & 0x3c] | SKB[2][c >>> 13 & 0x0f | c >>> 14 & 0x30]
                | SKB[3][c >>> 20 & 0x01 | c >>> 21 & 0x06 | c >>> 22 & 0x38];

            t = SKB[4][d & 0x3f] | SKB[5][d >>> 7 & 0x03 | d >>> 8 & 0x3c] | SKB[6][d >>> 15 & 0x3f]
                | SKB[7][d >>> 21 & 0x0f | d >>> 22 & 0x30];

            schedule[j++] = (t << 16 | s & 0x0000ffff) & 0xffffffff;
            s = s >>> 16 | t & 0xffff0000;

            s = s << 4 | s >>> 28;
            schedule[j++] = s & 0xffffffff;
        }

        return schedule;
    }

    private static int dEncrypt(int l, int r, int s, int e0, int e1, int[] ss) {
        int t;
        int u;
        int v;

        v = r ^ r >>> 16;
        u = v & e0;
        v = v & e1;
        u = u ^ u << 16 ^ r ^ ss[s];
        t = v ^ v << 16 ^ r ^ ss[s + 1];
        t = t >>> 4 | t << 28;

        l ^= SPTRANS[1][t & 0x3f] | SPTRANS[3][t >>> 8 & 0x3f] | SPTRANS[5][t >>> 16 & 0x3f]
            | SPTRANS[7][t >>> 24 & 0x3f]
            | SPTRANS[0][u & 0x3f] | SPTRANS[2][u >>> 8 & 0x3f] | SPTRANS[4][u >>> 16 & 0x3f]
            | SPTRANS[6][u >>> 24 & 0x3f];

        return l;
    }

    private static int[] body(int[] schedule, int eswap0, int eswap1) {
        int left = 0;
        int right = 0;
        int t;

        for (int j = 0; j < 25; j++) {
            for (int i = 0; i < ITERATIONS * 2; i += 4) {
                left = dEncrypt(left, right, i, eswap0, eswap1, schedule);
                right = dEncrypt(right, left, i + 2, eswap0, eswap1, schedule);
            }

            t = left;
            left = right;
            right = t;
        }

        t = right;

        right = left >>> 1 | left << 31;
        left = t >>> 1 | t << 31;

        left &= 0xffffffff;
        right &= 0xffffffff;

        int[] results = new int[2];

        permOp(right, left, 1, 0x55555555, results);
        right = results[0];
        left = results[1];

        permOp(left, right, 8, 0x00ff00ff, results);
        left = results[0];
        right = results[1];

        permOp(right, left, 2, 0x33333333, results);
        right = results[0];
        left = results[1];

        permOp(left, right, 16, 0x0000ffff, results);
        left = results[0];
        right = results[1];

        permOp(right, left, 4, 0x0f0f0f0f, results);
        right = results[0];
        left = results[1];

        int[] out = new int[2];

        out[0] = left;
        out[1] = right;

        return out;
    }

    public static final String ALPHABET = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

    private static final char[] CHARS = ALPHABET.toCharArray();

    /**
     * This method encrypts a string given a cleartext string and a "salt".
     * 
     * @param salt
     *            A two-character string representing the salt used to iterate
     *            the encryption engine.
     * @param original
     *            The string to be encrypted.
     * @return A string consisting of the 2-character salt followed by the
     *         encrypted string.
     */
    public static String crypt(String salt, String original) {
        // wwb -- Should do some sanity checks: salt needs to be 2 chars, in
        // alpha.
        while (salt.length() < 2) {
            salt += "A";
        }

        char[] buffer = new char[13];

        char charZero = salt.charAt(0);
        char charOne = salt.charAt(1);

        buffer[0] = charZero;
        buffer[1] = charOne;

        int eswap0 = ALPHABET.indexOf(charZero);
        int eswap1 = ALPHABET.indexOf(charOne) << 4;
        byte[] key = new byte[8];

        for (int i = 0; i < key.length; i++) {
            key[i] = (byte) 0;
        }

        for (int i = 0; i < key.length && i < original.length(); i++) {
            key[i] = (byte) (original.charAt(i) << 1);
        }

        int[] schedule = desSetKey(key);
        int[] out = body(schedule, eswap0, eswap1);

        byte[] b = new byte[9];

        intToFourBytes(out[0], b, 0);
        intToFourBytes(out[1], b, 4);
        b[8] = 0;

        for (int i = 2, y = 0, u = 0x80; i < 13; i++) {
            for (int j = 0, c = 0; j < 6; j++) {
                c <<= 1;

                if ((b[y] & u) != 0) {
                    c |= 1;
                }

                u >>>= 1;

                if (u == 0) {
                    y++;
                    u = 0x80;
                }

                buffer[i] = ALPHABET.charAt(c);
            }
        }

        return new String(buffer);
    }

    /**
     * This method encrypts a string given the cleartext string. A random salt
     * is generated using java.util.Random.
     * 
     * @param original
     *            The string to be encrypted.
     * @return A string consisting of the 2-character salt followed by the
     *         encrypted string.
     */
    public static String crypt(String original) {
        java.util.Random randomGenerator = new java.util.Random();
        int numSaltChars = CHARS.length;
        String salt;

        salt = String.valueOf(CHARS[Math.abs(randomGenerator.nextInt()) % numSaltChars])
            + CHARS[Math.abs(randomGenerator.nextInt()) % numSaltChars];

        return crypt(salt, original);
    }
}
