uk.co.infinityapps.rehpic.round.RoundFunctionImpl.java Source code

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Here is the source code for uk.co.infinityapps.rehpic.round.RoundFunctionImpl.java

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/*
 * Copyright (c) 2013 Infinity Apps Ltd
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is furnished
 * to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package uk.co.infinityapps.rehpic.round;

import uk.co.infinityapps.rehpic.permutation.KeyBasedPermutator;
import uk.co.infinityapps.rehpic.permutation.MixingPermutator;
import uk.co.infinityapps.rehpic.substitution.KeyBasedSubstitutionBox;
import uk.co.infinityapps.rehpic.utils.BitUtils;
import org.apache.commons.lang3.ArrayUtils;

import java.util.Arrays;
import java.util.BitSet;

/**
 * 
 * 
 * @author imberda
 * @version 1.0
 */
public class RoundFunctionImpl implements RoundFunction {

    private final KeyBasedPermutator permutator;
    private final KeyBasedSubstitutionBox substitutionBox;
    private final MixingPermutator mixingPermutator;

    public RoundFunctionImpl(final KeyBasedPermutator permutator, final KeyBasedSubstitutionBox substitutionBox,
            final MixingPermutator mixingPermutator) {
        this.permutator = permutator;
        this.substitutionBox = substitutionBox;
        this.mixingPermutator = mixingPermutator;
    }

    public byte[] encrypt(byte[] blockData, final byte[][] subKeys) {
        for (byte[] subKey : subKeys) {
            blockData = mixingPermutator.mix(blockData);
            blockData = permutator.shiftLeft(blockData, subKey);
            final BitSet blockBitSet = BitSet.valueOf(blockData);
            blockBitSet.xor(BitSet.valueOf(subKey));
            blockData = substitutionBox.subtitute(BitUtils.bitSetToByteArray(blockBitSet, blockData.length),
                    subKey);
        }
        return blockData;
    }

    public byte[] decrypt(byte[] blockData, final byte[][] subKeys) {
        final byte[][] reversedSubKeys = reverseSubKeysForDecryption(subKeys);

        for (byte[] subKey : reversedSubKeys) {
            blockData = substitutionBox.subtitute(blockData, subKey);
            BitSet xorBlockBitSet = BitSet.valueOf(blockData);
            xorBlockBitSet.xor(BitSet.valueOf(subKey));
            blockData = permutator.shiftRight(BitUtils.bitSetToByteArray(xorBlockBitSet, blockData.length), subKey);
            blockData = mixingPermutator.unmix(blockData);
        }
        return blockData;
    }

    private byte[][] reverseSubKeysForDecryption(final byte[][] subKeys) {
        final byte[][] reversedSubKeys = Arrays.copyOf(subKeys, subKeys.length);
        ArrayUtils.reverse(reversedSubKeys);
        return reversedSubKeys;
    }

}