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HBCI4j - Home Banking Computer Interface for Java - Clone from https://github.com/hbci4j/hbci4java

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/*  $Id: PBKDF2.java,v 1.1 2011/05/04 22:37:59 willuhn Exp $

    This file is part of CryptAlgs4Java
    Copyright (C) 2001-2010  Stefan Palme

    CryptAlgs4Java 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 2 of the License, or
    (at your option) any later version.

    CryptAlgs4Java 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 this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

package org.kapott.cryptalgs;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

// TODO: implement some SPI interface?
public class PBKDF2 {
    public static byte[] deriveKey(byte[] salt, long nof_iterations, byte[] pass, int dkLen, String algname) {
        try {
            SecretKeySpec keyspec = new SecretKeySpec(pass, algname);
            Mac mac = Mac.getInstance(algname);
            mac.init(keyspec);

            // see pkcs #5 v2.0 (RDH-2) bzw. pkcs #5 v2.1 (RDH-10)
            int hLen = mac.getMacLength();
            byte[] dk = new byte[dkLen];

            int l = ((dkLen - 1) / hLen) + 1;
            int r = dkLen - (l - 1) * hLen;

            // System.out.println("deriveKey: hLen="+hLen+"; l="+l+"; r="+r);

            byte[] t = new byte[hLen];
            for (long i = 0; i < l; i++) {
                Arrays.fill(t, (byte) 0);

                byte[] u = new byte[salt.length + 4];
                System.arraycopy(salt, 0, u, 0, salt.length);
                u[salt.length + 0] = (byte) (((i + 1) >> 24) & 0xFF);
                u[salt.length + 1] = (byte) (((i + 1) >> 16) & 0xFF);
                u[salt.length + 2] = (byte) (((i + 1) >> 8) & 0xFF);
                u[salt.length + 3] = (byte) (((i + 1) >> 0) & 0xFF);

                for (int j = 0; j < nof_iterations; j++) {
                    u = mac.doFinal(u);
                    for (int k = 0; k < t.length; k++) {
                        t[k] ^= u[k];
                    }
                }

                System.arraycopy(t, 0, dk, (int) (i * hLen), ((i != (l - 1)) ? hLen : r));
            }

            // System.out.print("derived key: ");
            // for (int i=0;i> 3) + 1) << 3;
        byte diff = (byte) (newlen - len);
        byte[] output = new byte[newlen];

        System.arraycopy(input, 0, output, 0, len);

        for (int i = len; i < newlen; i++) {
            output[i] = diff;
        }

        return output;
    }
}