BlockFilenameDecryptionStrategy.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 decryption strategy.
 */
class BlockFilenameDecryptionStrategy extends BasicFilenameDecryptionStrategy {

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


    /**
     * Block decryption.
     */
    protected byte[] decryptConcrete(EncFSVolume volume, byte[] encFileName, byte[] fileIv) throws EncFSCorruptDataException {
        try {
            return BlockCrypto.blockDecrypt(volume, fileIv, encFileName);
        } catch (InvalidAlgorithmParameterException|IllegalBlockSizeException|BadPaddingException e) {
            throw new EncFSCorruptDataException(e);
        }
    }


    /**
     * Remove padding after decryption.
     */
    protected String decryptPost(byte[] fileName) {
        int padLen = fileName[fileName.length-1];

        return new String(Arrays.copyOfRange(fileName, 0, fileName.length
                -padLen));
    }

}