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 * 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
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package sun.security.krb5.internal.crypto.dk;

import javax.crypto.Cipher;
import javax.crypto.Mac;
import javax.crypto.SecretKeyFactory;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.DESedeKeySpec;
import javax.crypto.spec.IvParameterSpec;
import java.security.spec.KeySpec;
import java.security.GeneralSecurityException;
import java.security.InvalidKeyException;
import java.util.Arrays;

public class Des3DkCrypto extends DkCrypto {

    private static final byte[] ZERO_IV = new byte[] {0, 0, 0, 0, 0, 0, 0, 0};

    public Des3DkCrypto() {
    }

    protected int getKeySeedLength() {
        return 168;   // bits; 3DES key material has 21 bytes
    }

    public byte[] stringToKey(char[] salt) throws GeneralSecurityException {
        byte[] saltUtf8 = null;
        try {
            saltUtf8 = charToUtf8(salt);
            return stringToKey(saltUtf8, null);
        } finally {
            if (saltUtf8 != null) {
                Arrays.fill(saltUtf8, (byte)0);
            }
            // Caller responsible for clearing its own salt
        }
    }

    private byte[] stringToKey(byte[] secretAndSalt, byte[] opaque)
        throws GeneralSecurityException {

        if (opaque != null && opaque.length > 0) {
            throw new RuntimeException("Invalid parameter to stringToKey");
        }

        byte[] tmpKey = randomToKey(nfold(secretAndSalt, getKeySeedLength()));
        return dk(tmpKey, KERBEROS_CONSTANT);
    }

    public byte[] parityFix(byte[] value)
        throws GeneralSecurityException {
        // fix key parity
        setParityBit(value);
        return value;
    }

    /*
     * From RFC 3961.
     *
     * The 168 bits of random key data are converted to a protocol key value
     * as follows.  First, the 168 bits are divided into three groups of 56
     * bits, which are expanded individually into 64 bits as in des3Expand().
     * Result is a 24 byte (192-bit) key.
     */
    protected byte[] randomToKey(byte[] in) {
        if (in.length != 21) {
            throw new IllegalArgumentException("input must be 168 bits");
        }

        byte[] one = keyCorrection(des3Expand(in, 0, 7));
        byte[] two = keyCorrection(des3Expand(in, 7, 14));
        byte[] three = keyCorrection(des3Expand(in, 14, 21));

        byte[] key = new byte[24];
        System.arraycopy(one, 0, key, 0, 8);
        System.arraycopy(two, 0, key, 8, 8);
        System.arraycopy(three, 0, key, 16, 8);

        return key;
    }

    private static byte[] keyCorrection(byte[] key) {
        // check for weak key
        try {
            if (DESKeySpec.isWeak(key, 0)) {
                key[7] = (byte)(key[7] ^ 0xF0);
            }
        } catch (InvalidKeyException ex) {
            // swallow, since it should never happen
        }
        return key;
    }

    
From RFC 3961.
Expands a 7-byte array into an 8-byte array that contains parity bits.
The 56 bits are expanded into 64 bits as follows:
  1  2  3  4  5  6  7  p
  9 10 11 12 13 14 15  p
  17 18 19 20 21 22 23  p
  25 26 27 28 29 30 31  p
  33 34 35 36 37 38 39  p
  41 42 43 44 45 46 47  p
  49 50 51 52 53 54 55  p
  56 48 40 32 24 16  8  p
(PI,P2,...,P8) are reserved for parity bits computed on the preceding
seven independent bits and set so that the parity of the octet is odd,
i.e., there is an odd number of "1" bits in the octet.
Params:
start – index of starting byte (inclusive)
end – index of ending byte (exclusive)/**
     * From RFC 3961.
     *
     * Expands a 7-byte array into an 8-byte array that contains parity bits.
     * The 56 bits are expanded into 64 bits as follows:
     *   1  2  3  4  5  6  7  p
     *   9 10 11 12 13 14 15  p
     *   17 18 19 20 21 22 23  p
     *   25 26 27 28 29 30 31  p
     *   33 34 35 36 37 38 39  p
     *   41 42 43 44 45 46 47  p
     *   49 50 51 52 53 54 55  p
     *   56 48 40 32 24 16  8  p
     *
     * (PI,P2,...,P8) are reserved for parity bits computed on the preceding
     * seven independent bits and set so that the parity of the octet is odd,
     * i.e., there is an odd number of "1" bits in the octet.
     *
     * @param start index of starting byte (inclusive)
     * @param end index of ending byte (exclusive)
     */
    private static byte[] des3Expand(byte[] input, int start, int end) {
        if ((end - start) != 7)
            throw new IllegalArgumentException(
                "Invalid length of DES Key Value:" + start + "," + end);

        byte[] result = new byte[8];
        byte last = 0;
        System.arraycopy(input, start, result, 0, 7);
        byte posn = 0;

        // Fill in last row
        for (int i = start; i < end; i++) {
            byte bit = (byte) (input[i]&0x01);
            if (debug) {
                System.out.println(i + ": " + Integer.toHexString(input[i]) +
                    " bit= " + Integer.toHexString(bit));
            }
            ++posn;
            if (bit != 0) {
                last |= (bit<<posn);
            }
        }

        if (debug) {
            System.out.println("last: " + Integer.toHexString(last));
        }
        result[7] = last;
        setParityBit(result);
        return result;
    }

    
Sets the parity bit (0th bit) in each byte so that each byte
contains an odd number of 1's.
/**
     * Sets the parity bit (0th bit) in each byte so that each byte
     * contains an odd number of 1's.
     */
    private static void setParityBit(byte[] key) {
        for (int i = 0; i < key.length; i++) {
            int b = key[i] & 0xfe;
            b |= (Integer.bitCount(b) & 1) ^ 1;
            key[i] = (byte) b;
        }
    }

    protected Cipher getCipher(byte[] key, byte[] ivec, int mode)
        throws GeneralSecurityException {
        // NoSuchAlgorithException
        SecretKeyFactory factory = SecretKeyFactory.getInstance("desede");

        // InvalidKeyException
        KeySpec spec = new DESedeKeySpec(key, 0);

        // InvalidKeySpecException
        SecretKey secretKey = factory.generateSecret(spec);

        // IV
        if (ivec == null) {
            ivec = ZERO_IV;
        }

        // NoSuchAlgorithmException, NoSuchPaddingException
        // NoSuchProviderException
        Cipher cipher = Cipher.getInstance("DESede/CBC/NoPadding");
        IvParameterSpec encIv = new IvParameterSpec(ivec, 0, ivec.length);

        // InvalidKeyException, InvalidAlgorithParameterException
        cipher.init(mode, secretKey, encIv);

        return cipher;
    }

    public int getChecksumLength() {
        return 20;  // bytes
    }

    protected byte[] getHmac(byte[] key, byte[] msg)
        throws GeneralSecurityException {

        SecretKey keyKi = new SecretKeySpec(key, "HmacSHA1");
        Mac m = Mac.getInstance("HmacSHA1");
        m.init(keyKi);
        return m.doFinal(msg);
    }
}