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The Apache Commons Codec package contains simple encoder and decoders for
various formats such as Base64 and Hexadecimal. In addition to these
widely used encoders and decoders, the codec package also maintains a
collection of phonetic encoding utilities.
/*
* ====================================================================
* 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.
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package org.apache.poi.poifs.crypt.temp;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
import org.apache.commons.compress.archivers.zip.ZipArchiveInputStream;
import org.apache.commons.compress.archivers.zip.ZipArchiveOutputStream;
import org.apache.commons.compress.archivers.zip.ZipFile;
import org.apache.commons.io.output.CloseShieldOutputStream;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
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.RandomSingleton;
import org.apache.poi.util.TempFile;
/**
* An example {@code ZipEntrySource} that has encrypted temp files to ensure that
* sensitive data is not stored in raw format on disk.
*/
@Beta
public final class AesZipFileZipEntrySource implements ZipEntrySource {
private static final Logger LOG = LogManager.getLogger(AesZipFileZipEntrySource.class);
private static final String PADDING = "PKCS5Padding";
private final File tmpFile;
private final ZipFile zipFile;
private final Cipher ci;
private boolean closed;
private 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.getEntries();
}
@Override
public ZipArchiveEntry getEntry(String path) {
return zipFile.getEntry(path);
}
@Override
public InputStream getInputStream(ZipArchiveEntry 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.atWarn().log("{} can't be removed (or was already removed).", tmpFile.getAbsolutePath());
}
}
closed = true;
}
@Override
public boolean isClosed() {
return closed;
}
public static AesZipFileZipEntrySource createZipEntrySource(InputStream is) throws IOException {
try {
// generate session key
byte[] ivBytes = new byte[16], keyBytes = new byte[16];
RandomSingleton.getInstance().nextBytes(ivBytes);
RandomSingleton.getInstance().nextBytes(keyBytes);
final File tmpFile = TempFile.createTempFile("protectedXlsx", ".zip");
try {
copyToFile(is, tmpFile, keyBytes, ivBytes);
return fileToSource(tmpFile, keyBytes, ivBytes);
} catch (IOException|RuntimeException e) {
if (!tmpFile.delete()) {
LOG.atInfo().log("Temp file was not deleted, may already have been deleted by another method.");
}
throw e;
}
} finally {
IOUtils.closeQuietly(is);
}
}
private static void copyToFile(InputStream is, File tmpFile, byte[] keyBytes, byte[] ivBytes) throws IOException {
SecretKeySpec skeySpec = new SecretKeySpec(keyBytes, CipherAlgorithm.aes128.jceId);
Cipher ciEnc = CryptoFunctions.getCipher(skeySpec, CipherAlgorithm.aes128, ChainingMode.cbc, ivBytes, Cipher.ENCRYPT_MODE, PADDING);
try (ZipArchiveInputStream zis = new ZipArchiveInputStream(is);
FileOutputStream fos = new FileOutputStream(tmpFile);
ZipArchiveOutputStream zos = new ZipArchiveOutputStream(fos)) {
ZipArchiveEntry ze;
while ((ze = zis.getNextZipEntry()) != 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()
ZipArchiveEntry zeNew = new ZipArchiveEntry(ze.getName());
zeNew.setComment(ze.getComment());
zeNew.setExtra(ze.getExtra());
zeNew.setTime(ze.getTime());
// zeNew.setMethod(ze.getMethod());
zos.putArchiveEntry(zeNew);
// don't close underlying ZipOutputStream
try (CipherOutputStream cos = new CipherOutputStream(CloseShieldOutputStream.wrap(zos), ciEnc)) {
IOUtils.copy(zis, cos);
}
zos.closeArchiveEntry();
}
}
}
private static AesZipFileZipEntrySource fileToSource(File tmpFile, byte[] keyBytes, byte[] ivBytes) throws IOException {
SecretKeySpec skeySpec = new SecretKeySpec(keyBytes, CipherAlgorithm.aes128.jceId);
Cipher ciDec = CryptoFunctions.getCipher(skeySpec, CipherAlgorithm.aes128, ChainingMode.cbc, ivBytes, Cipher.DECRYPT_MODE, PADDING);
return new AesZipFileZipEntrySource(tmpFile, ciDec);
}
}