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Apache POI - Java API To Access Microsoft Format Files
/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.poi.poifs.crypt.temp;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.SecureRandom;
import java.util.Enumeration;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.spec.SecretKeySpec;
import org.apache.poi.openxml4j.util.ZipEntrySource;
import org.apache.poi.poifs.crypt.ChainingMode;
import org.apache.poi.poifs.crypt.CipherAlgorithm;
import org.apache.poi.poifs.crypt.CryptoFunctions;
import org.apache.poi.util.Beta;
import org.apache.poi.util.IOUtils;
import org.apache.poi.util.POILogFactory;
import org.apache.poi.util.POILogger;
import org.apache.poi.util.TempFile;
/**
* An example ZipEntrySource that has encrypted temp files to ensure that
* sensitive data is not stored in raw format on disk.
*/
@Beta
public class AesZipFileZipEntrySource implements ZipEntrySource {
private static final POILogger LOG = POILogFactory.getLogger(AesZipFileZipEntrySource.class);
private final File tmpFile;
private final ZipFile zipFile;
private final Cipher ci;
private boolean closed;
public AesZipFileZipEntrySource(File tmpFile, Cipher ci) throws IOException {
this.tmpFile = tmpFile;
this.zipFile = new ZipFile(tmpFile);
this.ci = ci;
this.closed = false;
}
/**
* Note: the file sizes are rounded up to the next cipher block size,
* so don't rely on file sizes of these custom encrypted zip file entries!
*/
@Override
public Enumeration getEntries() {
return zipFile.entries();
}
@Override
public InputStream getInputStream(ZipEntry entry) throws IOException {
InputStream is = zipFile.getInputStream(entry);
return new CipherInputStream(is, ci);
}
@Override
public void close() throws IOException {
if(!closed) {
zipFile.close();
if (!tmpFile.delete()) {
LOG.log(POILogger.WARN, tmpFile.getAbsolutePath()+" can't be removed (or was already removed.");
}
}
closed = true;
}
@Override
public boolean isClosed() {
return closed;
}
public static AesZipFileZipEntrySource createZipEntrySource(InputStream is) throws IOException, GeneralSecurityException {
// generate session key
SecureRandom sr = new SecureRandom();
byte[] ivBytes = new byte[16], keyBytes = new byte[16];
sr.nextBytes(ivBytes);
sr.nextBytes(keyBytes);
final File tmpFile = TempFile.createTempFile("protectedXlsx", ".zip");
copyToFile(is, tmpFile, CipherAlgorithm.aes128, keyBytes, ivBytes);
IOUtils.closeQuietly(is);
return fileToSource(tmpFile, CipherAlgorithm.aes128, keyBytes, ivBytes);
}
private static void copyToFile(InputStream is, File tmpFile, CipherAlgorithm cipherAlgorithm, byte keyBytes[], byte ivBytes[]) throws IOException, GeneralSecurityException {
SecretKeySpec skeySpec = new SecretKeySpec(keyBytes, cipherAlgorithm.jceId);
Cipher ciEnc = CryptoFunctions.getCipher(skeySpec, cipherAlgorithm, ChainingMode.cbc, ivBytes, Cipher.ENCRYPT_MODE, "PKCS5Padding");
ZipInputStream zis = new ZipInputStream(is);
FileOutputStream fos = new FileOutputStream(tmpFile);
ZipOutputStream zos = new ZipOutputStream(fos);
ZipEntry ze;
while ((ze = zis.getNextEntry()) != null) {
// the cipher output stream pads the data, therefore we can't reuse the ZipEntry with set sizes
// as those will be validated upon close()
ZipEntry zeNew = new ZipEntry(ze.getName());
zeNew.setComment(ze.getComment());
zeNew.setExtra(ze.getExtra());
zeNew.setTime(ze.getTime());
// zeNew.setMethod(ze.getMethod());
zos.putNextEntry(zeNew);
FilterOutputStream fos2 = new FilterOutputStream(zos){
// don't close underlying ZipOutputStream
@Override
public void close() {}
};
CipherOutputStream cos = new CipherOutputStream(fos2, ciEnc);
IOUtils.copy(zis, cos);
cos.close();
fos2.close();
zos.closeEntry();
zis.closeEntry();
}
zos.close();
fos.close();
zis.close();
}
private static AesZipFileZipEntrySource fileToSource(File tmpFile, CipherAlgorithm cipherAlgorithm, byte keyBytes[], byte ivBytes[]) throws ZipException, IOException {
SecretKeySpec skeySpec = new SecretKeySpec(keyBytes, cipherAlgorithm.jceId);
Cipher ciDec = CryptoFunctions.getCipher(skeySpec, cipherAlgorithm, ChainingMode.cbc, ivBytes, Cipher.DECRYPT_MODE, "PKCS5Padding");
return new AesZipFileZipEntrySource(tmpFile, ciDec);
}
}