BlockCrypto.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 javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;


/**
 * Static methods for block cryptography.
 */
class BlockCrypto {

    /**
     * Returns a new block cipher object.
     */
    protected static Cipher newBlockCipher() throws EncFSUnsupportedException {
        return EncFSCrypto.getCipher(EncFSCrypto.BLOCK_CIPHER);
    }


    /**
     * Common method to perform a block operation.
     */
    private static byte[] blockOperation(EncFSVolume volume, byte[] ivSeed, byte[] data, int opMode) throws InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException {
        Cipher cipher = volume.getBlockCipher();
        EncFSCrypto.cipherInit(volume, opMode, cipher, ivSeed);
        return cipher.doFinal(data);
    }


    /**
     * Perform block encryption.
     */
    protected static byte[] blockDecrypt(EncFSVolume volume, byte[] ivSeed, byte[] data)
            throws InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException {
        return blockOperation(volume, ivSeed, data, Cipher.DECRYPT_MODE);
    }


    /**
     * Perform block decryption.
     */
    protected static byte[] blockEncrypt(EncFSVolume volume, byte[] ivSeed, byte[] data)
            throws IllegalBlockSizeException, InvalidAlgorithmParameterException, BadPaddingException {
        return blockOperation(volume, ivSeed, data, Cipher.ENCRYPT_MODE);
    }

}