Java example source code file (Des.java)

This example Java source code file (Des.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

charset, cipher, crypto, des, des\/cbc\/nopadding, generalsecurityexception, getpropertyaction, ivparameterspec, jce, krbcryptoexception, secretkey, secretkeyfactory, secretkeyspec, security, string, unable, util

The Des.java Java example source code

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 *
 *  (C) Copyright IBM Corp. 1999 All Rights Reserved.
 *  Copyright 1997 The Open Group Research Institute.  All rights reserved.
 */

package sun.security.krb5.internal.crypto;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.SecretKeyFactory;
import javax.crypto.SecretKey;
import java.security.GeneralSecurityException;
import javax.crypto.spec.IvParameterSpec;
import sun.security.krb5.KrbCryptoException;
import java.util.Arrays;
import sun.security.action.GetPropertyAction;

public final class Des {

    // RFC 3961 demands that UTF-8 encoding be used in DES's
    // string-to-key function. For historical reasons, some
    // implementations use a locale-specific encoding. Even
    // so, when the client and server use different locales,
    // they must agree on a common value, normally the one
    // used when the password is set/reset.
    //
    // The following system property is provided to perform the
    // string-to-key encoding. When set, the specified charset
    // name is used. Otherwise, the system default charset.

    private final static String CHARSET =
            java.security.AccessController.doPrivileged(
            new GetPropertyAction("sun.security.krb5.msinterop.des.s2kcharset"));

    private static final long[] bad_keys = {
        0x0101010101010101L, 0xfefefefefefefefeL,
        0x1f1f1f1f1f1f1f1fL, 0xe0e0e0e0e0e0e0e0L,
        0x01fe01fe01fe01feL, 0xfe01fe01fe01fe01L,
        0x1fe01fe00ef10ef1L, 0xe01fe01ff10ef10eL,
        0x01e001e001f101f1L, 0xe001e001f101f101L,
        0x1ffe1ffe0efe0efeL, 0xfe1ffe1ffe0efe0eL,
        0x011f011f010e010eL, 0x1f011f010e010e01L,
        0xe0fee0fef1fef1feL, 0xfee0fee0fef1fef1L
    };

    private static final byte[] good_parity = {
        1,       1,   2,   2,   4,   4,   7,   7,
        8,   8,   11,  11,  13,  13,  14,  14,
        16,  16,  19,  19,  21,  21,  22,  22,
        25,  25,  26,  26,  28,  28,  31,  31,
        32,  32,  35,  35,  37,  37,  38,  38,
        41,  41,  42,  42,  44,  44,  47,  47,
        49,  49,  50,  50,  52,  52,  55,  55,
        56,  56,  59,  59,  61,  61,  62,  62,
        64,  64,  67,  67,  69,  69,  70,  70,
        73,  73,  74,  74,  76,  76,  79,  79,
        81,  81,  82,  82,  84,  84,  87,  87,
        88,  88,  91,  91,  93,  93,  94,  94,
        97,  97,  98,  98,  100, 100, 103, 103,
        104, 104, 107, 107, 109, 109, 110, 110,
        112, 112, 115, 115, 117, 117, 118, 118,
        121, 121, 122, 122, 124, 124, 127, 127,
        (byte)128, (byte)128, (byte)131, (byte)131,
        (byte)133, (byte)133, (byte)134, (byte)134,
        (byte)137, (byte)137, (byte)138, (byte)138,
        (byte)140, (byte)140, (byte)143, (byte)143,
        (byte)145, (byte)145, (byte)146, (byte)146,
        (byte)148, (byte)148, (byte)151, (byte)151,
        (byte)152, (byte)152, (byte)155, (byte)155,
        (byte)157, (byte)157, (byte)158, (byte)158,
        (byte)161, (byte)161, (byte)162, (byte)162,
        (byte)164, (byte)164, (byte)167, (byte)167,
        (byte)168, (byte)168, (byte)171, (byte)171,
        (byte)173, (byte)173, (byte)174, (byte)174,
        (byte)176, (byte)176, (byte)179, (byte)179,
        (byte)181, (byte)181, (byte)182, (byte)182,
        (byte)185, (byte)185, (byte)186, (byte)186,
        (byte)188, (byte)188, (byte)191, (byte)191,
        (byte)193, (byte)193, (byte)194, (byte)194,
        (byte)196, (byte)196, (byte)199, (byte)199,
        (byte)200, (byte)200, (byte)203, (byte)203,
        (byte)205, (byte)205, (byte)206, (byte)206,
        (byte)208, (byte)208, (byte)211, (byte)211,
        (byte)213, (byte)213, (byte)214, (byte)214,
        (byte)217, (byte)217, (byte)218, (byte)218,
        (byte)220, (byte)220, (byte)223, (byte)223,
        (byte)224, (byte)224, (byte)227, (byte)227,
        (byte)229, (byte)229, (byte)230, (byte)230,
        (byte)233, (byte)233, (byte)234, (byte)234,
        (byte)236, (byte)236, (byte)239, (byte)239,
        (byte)241, (byte)241, (byte)242, (byte)242,
        (byte)244, (byte)244, (byte)247, (byte)247,
        (byte)248, (byte)248, (byte)251, (byte)251,
        (byte)253, (byte)253, (byte)254, (byte)254
    };

    public static final byte[] set_parity(byte[] key) {
        for (int i=0; i < 8; i++) {
            key[i] = good_parity[key[i] & 0xff];
        }
        return key;
    }

    public static final long set_parity(long key) {
        return octet2long(set_parity(long2octet(key)));
    }

    public static final boolean bad_key(long key) {
        for (int i = 0; i < bad_keys.length; i++) {
            if (bad_keys[i] == key) {
                return true;
            }
        }
        return false;
    }

    public static final boolean bad_key(byte[] key) {
        return bad_key(octet2long(key));
    }

    public static long octet2long(byte[] input) {
        return octet2long(input, 0);
    }

    public static long octet2long(byte[] input, int offset) {   //convert a 8-byte to a long
        long result = 0;
        for (int i = 0; i < 8; i++) {
            if (i + offset < input.length) {
                result |= (((long)input[i + offset]) & 0xffL) << ((7 - i) * 8);
            }
        }
        return result;
    }

    public static byte[] long2octet(long input) {
        byte[] output = new byte[8];
        for (int i = 0; i < 8; i++) {
            output[i] = (byte)((input >>> ((7 - i) * 8)) & 0xffL);
        }
        return output;
    }

    public static void long2octet(long input, byte[] output) {
        long2octet(input, output, 0);
    }

    public static void long2octet(long input, byte[] output, int offset) {
        for (int i = 0; i < 8; i++) {
            if (i + offset < output.length) {
                output[i + offset] =
                    (byte)((input >>> ((7 - i) * 8)) & 0xffL);
            }
        }
    }

    /**
     * Creates a DES cipher in Electronic Codebook mode, with no padding.
     * @param input plain text.
     * @param output the buffer for the result.
     * @param key DES the key to encrypt the text.
     * @param ivec initialization vector.
     *
     * @created by Yanni Zhang, Dec 6 99.
     */
    public static void cbc_encrypt (
                                    byte[] input,
                                    byte[] output,
                                    byte[] key,
                                    byte[] ivec,
                                    boolean encrypt) throws KrbCryptoException {

        Cipher cipher = null;

        try {
            cipher = Cipher.getInstance("DES/CBC/NoPadding");
        } catch (GeneralSecurityException e) {
            KrbCryptoException ke = new KrbCryptoException("JCE provider may not be installed. "
                                                           + e.getMessage());
            ke.initCause(e);
            throw ke;
        }
        IvParameterSpec params = new IvParameterSpec(ivec);
        SecretKeySpec skSpec = new SecretKeySpec(key, "DES");
        try {
            SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");
            //                  SecretKey sk = skf.generateSecret(skSpec);
            SecretKey sk = (SecretKey) skSpec;
            if (encrypt)
                cipher.init(Cipher.ENCRYPT_MODE, sk, params);
            else
                cipher.init(Cipher.DECRYPT_MODE, sk, params);
            byte[] result;
            result = cipher.doFinal(input);
            System.arraycopy(result, 0, output, 0, result.length);
        } catch (GeneralSecurityException e) {
            KrbCryptoException ke = new KrbCryptoException(e.getMessage());
            ke.initCause(e);
            throw ke;
        }
    }

    /**
     * Generates DES key from the password.
     * @param password a char[] used to create the key.
     * @return DES key.
     *
     * @modified by Yanni Zhang, Dec 6, 99
     */
    public static long char_to_key(char[] passwdChars) throws KrbCryptoException {
        long key = 0;
        long octet, octet1, octet2 = 0;
        byte[] cbytes = null;

        // Convert password to byte array
        try {
            if (CHARSET == null) {
                cbytes = (new String(passwdChars)).getBytes();
            } else {
                cbytes = (new String(passwdChars)).getBytes(CHARSET);
            }
        } catch (Exception e) {
            // clear-up sensitive information
            if (cbytes != null) {
                Arrays.fill(cbytes, 0, cbytes.length, (byte) 0);
            }
            KrbCryptoException ce =
                new KrbCryptoException("Unable to convert passwd, " + e);
            ce.initCause(e);
            throw ce;
        }

        // pad data
        byte[] passwdBytes = pad(cbytes);

        byte[] newkey = new byte[8];
        int length = (passwdBytes.length / 8) + (passwdBytes.length % 8  == 0 ? 0 : 1);
        for (int i = 0; i < length; i++) {
            octet = octet2long(passwdBytes, i * 8) & 0x7f7f7f7f7f7f7f7fL;
            if (i % 2 == 1) {
                octet1 = 0;
                for (int j = 0; j < 64; j++) {
                    octet1 |= ((octet & (1L << j)) >>> j) << (63 - j);
                }
                octet = octet1 >>> 1;
            }
            key ^= (octet << 1);
        }
        key = set_parity(key);
        if (bad_key(key)) {
            byte [] temp = long2octet(key);
            temp[7] ^= 0xf0;
            key = octet2long(temp);
        }

        newkey = des_cksum(long2octet(key), passwdBytes, long2octet(key));
        key = octet2long(set_parity(newkey));
        if (bad_key(key)) {
            byte [] temp = long2octet(key);
            temp[7] ^= 0xf0;
            key = octet2long(temp);
        }

        // clear-up sensitive information
        if (cbytes != null) {
            Arrays.fill(cbytes, 0, cbytes.length, (byte) 0);
        }
        if (passwdBytes != null) {
            Arrays.fill(passwdBytes, 0, passwdBytes.length, (byte) 0);
        }

        return key;
    }

    /**
     * Encrypts the message blocks using DES CBC and output the
     * final block of 8-byte ciphertext.
     * @param ivec Initialization vector.
     * @param msg Input message as an byte array.
     * @param key DES key to encrypt the message.
     * @return the last block of ciphertext.
     *
     * @created by Yanni Zhang, Dec 6, 99.
     */
    public static byte[] des_cksum(byte[] ivec, byte[] msg, byte[] key) throws KrbCryptoException {
        Cipher cipher = null;

        byte[] result = new byte[8];
        try{
            cipher = Cipher.getInstance("DES/CBC/NoPadding");
        } catch (Exception e) {
            KrbCryptoException ke = new KrbCryptoException("JCE provider may not be installed. "
                                                           + e.getMessage());
            ke.initCause(e);
            throw ke;
        }
        IvParameterSpec params = new IvParameterSpec(ivec);
        SecretKeySpec skSpec = new SecretKeySpec(key, "DES");
        try {
            SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");
            // SecretKey sk = skf.generateSecret(skSpec);
            SecretKey sk = (SecretKey) skSpec;
            cipher.init(Cipher.ENCRYPT_MODE, sk, params);
            for (int i = 0; i < msg.length / 8; i++) {
                result = cipher.doFinal(msg, i * 8, 8);
                cipher.init(Cipher.ENCRYPT_MODE, sk, (new IvParameterSpec(result)));
            }
        }
        catch (GeneralSecurityException e) {
            KrbCryptoException ke = new KrbCryptoException(e.getMessage());
            ke.initCause(e);
            throw ke;
        }
        return result;
    }

    /**
     * Pads the data so that its length is a multiple of 8 bytes.
     * @param data the raw data.
     * @return the data being padded.
     *
     * @created by Yanni Zhang, Dec 6 99. //Kerberos does not use PKCS5 padding.
     */
    static byte[] pad(byte[] data) {
        int len;
        if (data.length < 8) len = data.length;
        else len = data.length % 8;
        if (len == 0) return data;
        else {
            byte[] padding = new byte[ 8 - len + data.length];
            for (int i = padding.length - 1; i > data.length - 1; i--) {
                padding[i] = 0;
            }
            System.arraycopy(data, 0, padding, 0, data.length);
            return padding;
        }
    }

    // Caller is responsible for clearing password
    public static byte[] string_to_key_bytes(char[] passwdChars)
        throws KrbCryptoException {
        return long2octet(char_to_key(passwdChars));
    }
}