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TrueZIP is a Java based Virtual File System (VFS) to enable transparent, multi-threaded read/write access to archive files (ZIP, TAR etc.) as if they were directories. Archive files may be arbitrarily nested and the nesting level is only limited by heap and file system size.
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/*
 * Copyright (C) 2006-2010 Schlichtherle IT Services
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.schlichtherle.io;

import de.schlichtherle.crypto.io.raes.*;
import de.schlichtherle.io.rof.*;

import java.io.*;

/**
 * Saves and restores the contents of arbitrary files to and from the RAES
 * file format for encryption and decryption.
 * Note that this class is not intended to access RAES encrypted ZIP files -
 * use the {@link File} class for this task instead.
 *
 * @author Christian Schlichtherle
 * @version $Id: RaesFiles.java,v 1.4 2010/08/20 13:09:41 christian_schlichtherle Exp $
 */
public class RaesFiles {

    /** You cannot instantiate this class. */
    protected RaesFiles() {
    }

    /**
     * Encrypts the given plain file to the given RAES file.
     * This version uses the default ArchiveDetector to detect any archive
     * files in its parent directory path except the files themselves, which
     * are not recognized as archive files.
     */
    public static void encrypt(
            final String plainFilePath,
            final String raesFilePath)
    throws IOException {
        encrypt(plainFilePath, raesFilePath, File.getDefaultArchiveDetector());
    }

    /**
     * Encrypts the given plain file to the given RAES file,
     * using the provided ArchiveDetector to detect any archive files in its
     * parent directory path except the files themselves, which are not
     * recognized as archive files.
     */
    public static void encrypt(
            final String plainFilePath,
            final String raesFilePath,
            final ArchiveDetector detector)
    throws IOException {
        final File plainFile = getNonArchiveFile(plainFilePath, detector);
        final InputStream in = detector.createFileInputStream(plainFile);
        final RaesOutputStream out;
        try {
            final File raesFile = getNonArchiveFile(raesFilePath, detector);
            final RaesParameters params = new KeyManagerRaesParameters(
                    raesFile.getCanonicalPath()); // use canonical path name
            out = RaesOutputStream.getInstance(
                    detector.createFileOutputStream(raesFile, false),
                    params);
        } catch (IOException failure) {
            in.close();
            throw failure;
        }
        File.cp(in, out);
    }

    /**
     * Decrypts the given RAES file to the given plain file.
     * This version uses the default ArchiveDetector to detect any archive
     * files in its parent directory path except the files themselves, which
     * are not recognized as archive files.
     */
    public static void decrypt(
            final String raesFilePath,
            final String plainFilePath,
            final boolean strongAuthentication)
    throws IOException {
        decrypt(raesFilePath, plainFilePath, strongAuthentication,
                File.getDefaultArchiveDetector());
    }

    /**
     * Decrypts the given RAES file to the given plain file,
     * using the provided ArchiveDetector to detect any archvie files in its
     * parent directory path except the files themselves, which are not
     * recognized as archive files.
     * 
     * @param strongAuthentication If this is {@code true}, the whole
     *        contents of encrypted file get authenticated, which can be a
     *        time consuming operation.
     *        Otherwise, only the key/password and the file length get
     *        authenticated.
     */
    public static void decrypt(
            final String raesFilePath,
            final String plainFilePath,
            final boolean strongAuthentication,
            final ArchiveDetector detector)
    throws IOException {
        final File raesFile = getNonArchiveFile(raesFilePath, detector);
        final RaesParameters params = new KeyManagerRaesParameters(
                raesFile.getCanonicalPath()); // use canonical path name
        final RaesReadOnlyFile rrof
                = RaesReadOnlyFile.getInstance(raesFile, params);
        final InputStream in;
        final OutputStream out;
        try {
            if (strongAuthentication)
                rrof.authenticate();
            in = new ReadOnlyFileInputStream(rrof);
            final File plainFile = getNonArchiveFile(plainFilePath, detector);
            out = detector.createFileOutputStream(plainFile, false);
        } catch (IOException failure) {
            rrof.close();
            throw failure;
        }
        File.cp(in, out);
    }

    /**
     * Creates a file object which uses the provided ArchiveDetector,
     * but does not recognize its own pathname as an archive file.
     * Please note that this method just creates a file object,
     * and does not actually operate on the file system.
     */
    private static final File getNonArchiveFile(
            final String path,
            final ArchiveDetector detector) {
        final File file = detector.createFile(path);
        return ArchiveDetector.NULL.createFile(file.getParentFile(), file.getName());
    }
}