/*
* Copyright 2008 Pirion Systems Pty Ltd, 139 Warry St,
* Fortitude Valley, Queensland, Australia
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package com.sun.pdfview.decrypt;
import java.nio.ByteBuffer;
import java.util.Map;
import com.sun.pdfview.PDFObject;
import com.sun.pdfview.PDFParseException;
/**
* Implements Version 4 standard decryption, whereby the Encrypt dictionary
* contains a list of named 'crypt filters', each of which is the equivalent
* of a {@link PDFDecrypter}. In addition to this list of crypt filters,
* the name of the filter to use for streams and the default filter to use
* for strings is specified. Requests to decode a stream with a named
* decrypter (typically Identity) instead of the default decrypter
* are honoured.
*
* @author Luke Kirby
*/
public class CryptFilterDecrypter implements PDFDecrypter {
/** Maps from crypt filter names to their corresponding decrypters */
private Map<String, PDFDecrypter> decrypters;
/** The default decrypter for stream content */
private PDFDecrypter defaultStreamDecrypter;
/** The default decrypter for string content */
private PDFDecrypter defaultStringDecrypter;
/**
* Class constructor
* @param decrypters a map of crypt filter names to their corresponding
* decrypters. Must already contain the Identity filter.
* @param defaultStreamCryptName the crypt filter name of the default
* stream decrypter
* @param defaultStringCryptName the crypt filter name of the default
* string decrypter
* @throws PDFParseException if one of the named defaults is not
* present in decrypters
*/
public CryptFilterDecrypter(
Map<String, PDFDecrypter> decrypters,
String defaultStreamCryptName,
String defaultStringCryptName)
throws PDFParseException {
this.decrypters = decrypters;
assert this.decrypters.containsKey("Identity") :
"Crypt Filter map does not contain required Identity filter";
defaultStreamDecrypter = this.decrypters.get(defaultStreamCryptName);
if (defaultStreamDecrypter == null) {
throw new PDFParseException(
"Unknown crypt filter specified as default for streams: " +
defaultStreamCryptName);
}
defaultStringDecrypter = this.decrypters.get(defaultStringCryptName);
if (defaultStringDecrypter == null) {
throw new PDFParseException(
"Unknown crypt filter specified as default for strings: " +
defaultStringCryptName);
}
}
@Override
public ByteBuffer decryptBuffer(
String cryptFilterName, PDFObject streamObj, ByteBuffer streamBuf)
throws PDFParseException {
final PDFDecrypter decrypter;
if (cryptFilterName == null) {
decrypter = defaultStreamDecrypter;
} else {
decrypter = decrypters.get(cryptFilterName);
if (decrypter == null) {
throw new PDFParseException("Unknown CryptFilter: " +
cryptFilterName);
}
}
return decrypter.decryptBuffer(
// elide the filter name to prevent V2 decrypters from
// complaining about a crypt filter name
null,
// if there's a specific crypt filter being used then objNum
// and objGen shouldn't contribute to the key, so we
// should make sure that no streamObj makes its way through
cryptFilterName != null ? null : streamObj,
streamBuf);
}
@Override
public String decryptString(int objNum, int objGen, String inputBasicString)
throws PDFParseException {
return defaultStringDecrypter.decryptString(objNum, objGen, inputBasicString);
}
@Override
public boolean isEncryptionPresent() {
for (final PDFDecrypter decrypter : decrypters.values()) {
if (decrypter.isEncryptionPresent()) {
return true;
}
}
return false;
}
@Override
public boolean isEncryptionPresent(String cryptFilterName) {
PDFDecrypter decrypter = decrypters.get(cryptFilterName);
return decrypter != null && decrypter.isEncryptionPresent(cryptFilterName);
}
@Override
public boolean isOwnerAuthorised() {
for (final PDFDecrypter decrypter : decrypters.values()) {
if (decrypter.isOwnerAuthorised()) {
return true;
}
}
return false;
}
}