BlockFilenameEncryptionStrategy.java

/*
 * EncFS Java Library
 * Copyright (C) 2013 encfs-java authors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Lesser General Public License for more details.
 */
package org.mrpdaemon.sec.encfs;

import java.security.InvalidAlgorithmParameterException;
import java.util.Arrays;
import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;


/**
 * Implementation of block filename encryption strategy.
 */
class BlockFilenameEncryptionStrategy extends BasicFilenameEncryptionStrategy {

    BlockFilenameEncryptionStrategy(EncFSVolume volume, String volumePath) {
        super(volume, volumePath, EncFSFilenameEncryptionAlgorithm.BLOCK);
    }


    /**
     * Block encryption.
     */
    @Override
    protected byte[] encryptConcrete(EncFSVolume volume, byte[] paddedDecFileName, byte[] fileIv) throws EncFSCorruptDataException {
        try {
            return BlockCrypto.blockEncrypt(volume, fileIv, paddedDecFileName);
        } catch (InvalidAlgorithmParameterException|IllegalBlockSizeException|BadPaddingException e) {
            throw new EncFSCorruptDataException(e);
        }
    }


    /**
     * Padding implementation.
     */
    protected byte[] getPaddedDecFilename(byte[] decFileName) {
        // Pad to the nearest 16 bytes, add a full block if needed
        int padBytesSize = 16;
        int padLen = padBytesSize-(decFileName.length%padBytesSize);
        if (padLen==0) {
            padLen = padBytesSize;
        }
        byte[] paddedDecFileName = Arrays.copyOf(decFileName,
                decFileName.length+padLen);
        Arrays.fill(paddedDecFileName, decFileName.length,
                paddedDecFileName.length, (byte) padLen);
        return paddedDecFileName;
    }

}