org.apache.poi.poifs.crypt.temp.EncryptedTempData Maven / Gradle / Ivy
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/*
* ====================================================================
* 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.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.spec.SecretKeySpec;
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.POILogFactory;
import org.apache.poi.util.POILogger;
import org.apache.poi.util.TempFile;
/**
* EncryptedTempData can be used to buffer binary data in a secure way, by using encrypted temp files.
*/
@Beta
public class EncryptedTempData {
private static POILogger LOG = POILogFactory.getLogger(EncryptedTempData.class);
private final static CipherAlgorithm cipherAlgorithm = CipherAlgorithm.aes128;
private final static String PADDING = "PKCS5Padding";
private final SecretKeySpec skeySpec;
private final byte[] ivBytes;
private final File tempFile;
public EncryptedTempData() throws IOException {
SecureRandom sr = new SecureRandom();
ivBytes = new byte[16];
byte[] keyBytes = new byte[16];
sr.nextBytes(ivBytes);
sr.nextBytes(keyBytes);
skeySpec = new SecretKeySpec(keyBytes, cipherAlgorithm.jceId);
tempFile = TempFile.createTempFile("poi-temp-data", ".tmp");
}
/**
* Returns the output stream for writing the data.
* Make sure to close it, otherwise the last cipher block is not written completely.
*
* @return the outputstream
* @throws IOException if the writing to the underlying file fails
*/
public OutputStream getOutputStream() throws IOException {
Cipher ciEnc = CryptoFunctions.getCipher(skeySpec, cipherAlgorithm, ChainingMode.cbc, ivBytes, Cipher.ENCRYPT_MODE, PADDING);
return new CipherOutputStream(new FileOutputStream(tempFile), ciEnc);
}
/**
* Returns the input stream for reading the previously written encrypted data
*
* @return the inputstream
* @throws IOException if the reading of the underlying file fails
*/
public InputStream getInputStream() throws IOException {
Cipher ciDec = CryptoFunctions.getCipher(skeySpec, cipherAlgorithm, ChainingMode.cbc, ivBytes, Cipher.DECRYPT_MODE, PADDING);
return new CipherInputStream(new FileInputStream(tempFile), ciDec);
}
/**
* Removes the temporarily backing file
*/
public void dispose() {
if (!tempFile.delete()) {
LOG.log(POILogger.WARN, tempFile.getAbsolutePath()+" can't be removed (or was already removed.");
}
}
}