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/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* 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 org.apache.xml.security.samples.encryption;
import java.io.File;
import java.io.FileOutputStream;
import java.security.Key;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;
import org.apache.xml.security.encryption.XMLCipher;
import org.apache.xml.security.utils.JavaUtils;
import org.apache.xml.security.utils.EncryptionConstants;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.OutputKeys;
/**
* This sample demonstrates how to decrypt data inside an xml document.
*
* @author Vishal Mahajan (Sun Microsystems)
*/
public class Decrypter {
/** {@link org.apache.commons.logging} logging facility */
static org.apache.commons.logging.Log log =
org.apache.commons.logging.LogFactory.getLog(
Decrypter.class.getName());
static {
org.apache.xml.security.Init.init();
}
private static Document loadEncryptionDocument() throws Exception {
String fileName = "encryptedInfo.xml";
File encryptionFile = new File(fileName);
javax.xml.parsers.DocumentBuilderFactory dbf =
javax.xml.parsers.DocumentBuilderFactory.newInstance();
dbf.setNamespaceAware(true);
javax.xml.parsers.DocumentBuilder db = dbf.newDocumentBuilder();
Document document = db.parse(encryptionFile);
System.out.println(
"Encryption document loaded from " +
encryptionFile.toURL().toString());
return document;
}
private static SecretKey loadKeyEncryptionKey() throws Exception {
String fileName = "kek";
String jceAlgorithmName = "DESede";
File kekFile = new File(fileName);
DESedeKeySpec keySpec =
new DESedeKeySpec(JavaUtils.getBytesFromFile(fileName));
SecretKeyFactory skf =
SecretKeyFactory.getInstance(jceAlgorithmName);
SecretKey key = skf.generateSecret(keySpec);
System.out.println(
"Key encryption key loaded from " + kekFile.toURL().toString());
return key;
}
private static void outputDocToFile(Document doc, String fileName)
throws Exception {
File encryptionFile = new File(fileName);
FileOutputStream f = new FileOutputStream(encryptionFile);
TransformerFactory factory = TransformerFactory.newInstance();
Transformer transformer = factory.newTransformer();
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(f);
transformer.transform(source, result);
f.close();
System.out.println(
"Wrote document containing decrypted data to " +
encryptionFile.toURL().toString());
}
public static void main(String unused[]) throws Exception {
Document document = loadEncryptionDocument();
Element encryptedDataElement =
(Element) document.getElementsByTagNameNS(
EncryptionConstants.EncryptionSpecNS,
EncryptionConstants._TAG_ENCRYPTEDDATA).item(0);
/*
* Load the key to be used for decrypting the xml data
* encryption key.
*/
Key kek = loadKeyEncryptionKey();
String providerName = "BC";
XMLCipher xmlCipher =
XMLCipher.getInstance();
/*
* The key to be used for decrypting xml data would be obtained
* from the keyinfo of the EncrypteData using the kek.
*/
xmlCipher.init(XMLCipher.DECRYPT_MODE, null);
xmlCipher.setKEK(kek);
/*
* The following doFinal call replaces the encrypted data with
* decrypted contents in the document.
*/
xmlCipher.doFinal(document, encryptedDataElement);
outputDocToFile(document, "decryptedInfo.xml");
}
}
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