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/*
* Copyright 1999-2005 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.
*/
/* $Id$ */
package org.apache.fop.pdf;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.Provider;
import java.security.Security;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* This class acts as a factory for PDF encryption support. It enables the
* feature to be optional to FOP depending on the availability of JCE.
*/
public class PDFEncryptionManager {
/** logging instance */
protected static Log log = LogFactory.getLog(PDFEncryptionManager.class);
/**
* Indicates whether JCE is available.
* @return boolean true if JCE is present
*/
public static boolean isJCEAvailable() {
try {
/*Class clazz =*/ Class.forName("javax.crypto.Cipher");
return true;
} catch (ClassNotFoundException e) {
return false;
}
}
/**
* Checks whether the necessary algorithms are available.
* @return boolean True if all necessary algorithms are present
*/
public static boolean checkAvailableAlgorithms() {
if (!isJCEAvailable()) {
return false;
} else {
Provider[] providers;
providers = Security.getProviders("Cipher.RC4");
if (providers == null) {
log.warn("Cipher provider for RC4 not available.");
return false;
}
providers = Security.getProviders("MessageDigest.MD5");
if (providers == null) {
log.warn("MessageDigest provider for MD5 not available.");
return false;
}
return true;
}
}
/**
* Sets up PDF encryption if PDF encryption is requested by registering
* a <code>PDFEncryptionParams</code> object with the user agent and if
* the necessary cryptographic support is available.
* @param params the PDF encryption params or null to disable encryption
* @param pdf the PDF document to setup encryption for
*/
public static void setupPDFEncryption(PDFEncryptionParams params,
PDFDocument pdf) {
if (pdf == null) {
throw new NullPointerException("PDF document must not be null");
}
if (params != null) {
if (!checkAvailableAlgorithms()) {
if (isJCEAvailable()) {
log.warn("PDF encryption has been requested, JCE is "
+ "available but there's no "
+ "JCE provider available that provides the "
+ "necessary algorithms. The PDF won't be "
+ "encrypted.");
} else {
log.warn("PDF encryption has been requested but JCE is "
+ "unavailable! The PDF won't be encrypted.");
}
}
pdf.setEncryption(params);
}
}
/**
* Creates a new PDFEncryption instance if PDF encryption is available.
* @param objnum PDF object number
* @param params PDF encryption parameters
* @return PDFEncryption the newly created instance, null if PDF encryption
* is unavailable.
*/
public static PDFEncryption newInstance(int objnum, PDFEncryptionParams params) {
try {
Class clazz = Class.forName("org.apache.fop.pdf.PDFEncryptionJCE");
Method makeMethod = clazz.getMethod("make",
new Class[] {int.class, PDFEncryptionParams.class});
Object obj = makeMethod.invoke(null,
new Object[] {new Integer(objnum), params});
return (PDFEncryption)obj;
} catch (ClassNotFoundException e) {
if (checkAvailableAlgorithms()) {
System.out.println("JCE and algorithms available, but the "
+ "implementation class unavailable. Please do a full "
+ "rebuild.");
}
return null;
} catch (NoSuchMethodException e) {
e.printStackTrace();
return null;
} catch (IllegalAccessException e) {
e.printStackTrace();
return null;
} catch (InvocationTargetException e) {
e.printStackTrace();
return null;
}
}
}
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