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/*
* $Id: PdfEncryption.java,v 1.44 2004/12/27 07:09:54 blowagie Exp $
* $Name: $
*
* Copyright 2001, 2002 Paulo Soares
*
* The contents of this file are subject to the Mozilla Public License Version 1.1
* (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the License.
*
* The Original Code is 'iText, a free JAVA-PDF library'.
*
* The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
* the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie.
* All Rights Reserved.
* Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
* are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved.
*
* Contributor(s): all the names of the contributors are added in the source code
* where applicable.
*
* Alternatively, the contents of this file may be used under the terms of the
* LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
* provisions of LGPL are applicable instead of those above. If you wish to
* allow use of your version of this file only under the terms of the LGPL
* License and not to allow others to use your version of this file under
* the MPL, indicate your decision by deleting the provisions above and
* replace them with the notice and other provisions required by the LGPL.
* If you do not delete the provisions above, a recipient may use your version
* of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the MPL as stated above or under the terms of the GNU
* Library General Public License as published by the Free Software Foundation;
* either version 2 of the License, or 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 Library general Public License for more
* details.
*
* If you didn't download this code from the following link, you should check if
* you aren't using an obsolete version:
* http://www.lowagie.com/iText/
*/
package com.lowagie.text.pdf;
import java.security.MessageDigest;
import com.lowagie.text.ExceptionConverter;
/**
*
* @author Paulo Soares ([email protected])
* @author Kazuya Ujihara
*/
public class PdfEncryption {
static final byte pad[] = {
(byte)0x28, (byte)0xBF, (byte)0x4E, (byte)0x5E, (byte)0x4E, (byte)0x75,
(byte)0x8A, (byte)0x41, (byte)0x64, (byte)0x00, (byte)0x4E, (byte)0x56,
(byte)0xFF, (byte)0xFA, (byte)0x01, (byte)0x08, (byte)0x2E, (byte)0x2E,
(byte)0x00, (byte)0xB6, (byte)0xD0, (byte)0x68, (byte)0x3E, (byte)0x80,
(byte)0x2F, (byte)0x0C, (byte)0xA9, (byte)0xFE, (byte)0x64, (byte)0x53,
(byte)0x69, (byte)0x7A};
byte state[] = new byte[256];
int x;
int y;
/** The encryption key for a particular object/generation */
byte key[];
/** The encryption key length for a particular object/generation */
int keySize;
/** The global encryption key */
byte mkey[];
/** Work area to prepare the object/generation bytes */
byte extra[] = new byte[5];
/** The message digest algorithm MD5 */
MessageDigest md5;
/** The encryption key for the owner */
byte ownerKey[] = new byte[32];
/** The encryption key for the user */
byte userKey[] = new byte[32];
int permissions;
byte documentID[];
static long seq = System.currentTimeMillis();
public PdfEncryption() {
try {
md5 = MessageDigest.getInstance("MD5");
}
catch (Exception e) {
throw new ExceptionConverter(e);
}
}
/**
*/
private byte[] padPassword(byte userPassword[]) {
byte userPad[] = new byte[32];
if (userPassword == null) {
System.arraycopy(pad, 0, userPad, 0, 32);
}
else {
System.arraycopy(userPassword, 0, userPad, 0, Math.min(userPassword.length, 32));
if (userPassword.length < 32)
System.arraycopy(pad, 0, userPad, userPassword.length, 32 - userPassword.length);
}
return userPad;
}
/**
*/
private byte[] computeOwnerKey(byte userPad[], byte ownerPad[], boolean strength128Bits) {
byte ownerKey[] = new byte[32];
byte digest[] = md5.digest(ownerPad);
if (strength128Bits) {
byte mkey[] = new byte[16];
for (int k = 0; k < 50; ++k)
digest = md5.digest(digest);
System.arraycopy(userPad, 0, ownerKey, 0, 32);
for (int i = 0; i < 20; ++i) {
for (int j = 0; j < mkey.length ; ++j)
mkey[j] = (byte)(digest[j] ^ i);
prepareRC4Key(mkey);
encryptRC4(ownerKey);
}
}
else {
prepareRC4Key(digest, 0, 5);
encryptRC4(userPad, ownerKey);
}
return ownerKey;
}
/**
*
* ownerKey, documentID must be setuped
*/
private void setupGlobalEncryptionKey(byte[] documentID, byte userPad[], byte ownerKey[], int permissions, boolean strength128Bits) {
this.documentID = documentID;
this.ownerKey = ownerKey;
this.permissions = permissions;
mkey = new byte[strength128Bits ? 16 : 5];
//fixed by ujihara in order to follow PDF refrence
md5.reset();
md5.update(userPad);
md5.update(ownerKey);
byte ext[] = new byte[4];
ext[0] = (byte)permissions;
ext[1] = (byte)(permissions >> 8);
ext[2] = (byte)(permissions >> 16);
ext[3] = (byte)(permissions >> 24);
md5.update(ext, 0, 4);
if (documentID != null) md5.update(documentID);
byte digest[] = md5.digest();
if (mkey.length == 16) {
for (int k = 0; k < 50; ++k)
digest = md5.digest(digest);
}
System.arraycopy(digest, 0, mkey, 0, mkey.length);
}
/**
*
* mkey must be setuped
*/
private void setupUserKey() {
if (mkey.length == 16) {
md5.update(pad);
byte digest[] = md5.digest(documentID);
System.arraycopy(digest, 0, userKey, 0, 16);
for (int k = 16; k < 32; ++k)
userKey[k] = 0;
for (int i = 0; i < 20; ++i) {
for (int j = 0; j < mkey.length; ++j)
digest[j] = (byte)(mkey[j] ^ i);
prepareRC4Key(digest, 0, mkey.length);
encryptRC4(userKey, 0, 16);
}
}
else {
prepareRC4Key(mkey);
encryptRC4(pad, userKey);
}
}
public void setupAllKeys(byte userPassword[], byte ownerPassword[], int permissions, boolean strength128Bits) {
if (ownerPassword == null || ownerPassword.length == 0)
ownerPassword = md5.digest(createDocumentId());
permissions |= strength128Bits ? 0xfffff0c0 : 0xffffffc0;
permissions &= 0xfffffffc;
//PDF refrence 3.5.2 Standard Security Handler, Algorithum 3.3-1
//If there is no owner password, use the user password instead.
byte userPad[] = padPassword(userPassword);
byte ownerPad[] = padPassword(ownerPassword);
this.ownerKey = computeOwnerKey(userPad, ownerPad, strength128Bits);
documentID = createDocumentId();
setupByUserPad(this.documentID, userPad, this.ownerKey, permissions, strength128Bits);
}
public static byte[] createDocumentId() {
MessageDigest md5;
try {
md5 = MessageDigest.getInstance("MD5");
}
catch (Exception e) {
throw new ExceptionConverter(e);
}
long time = System.currentTimeMillis();
long mem = Runtime.getRuntime().freeMemory();
String s = time + "+" + mem + "+" + (seq++);
return md5.digest(s.getBytes());
}
/**
*/
public void setupByUserPassword(byte[] documentID, byte userPassword[], byte ownerKey[], int permissions, boolean strength128Bits) {
setupByUserPad(documentID, padPassword(userPassword), ownerKey, permissions, strength128Bits);
}
/**
*/
private void setupByUserPad(byte[] documentID, byte userPad[], byte ownerKey[], int permissions, boolean strength128Bits) {
setupGlobalEncryptionKey(documentID, userPad, ownerKey, permissions, strength128Bits);
setupUserKey();
}
/**
*/
public void setupByOwnerPassword(byte[] documentID, byte ownerPassword[], byte userKey[], byte ownerKey[], int permissions, boolean strength128Bits) {
setupByOwnerPad(documentID, padPassword(ownerPassword), userKey, ownerKey, permissions, strength128Bits);
}
private void setupByOwnerPad(byte[] documentID, byte ownerPad[], byte userKey[], byte ownerKey[], int permissions, boolean strength128Bits) {
byte userPad[] = computeOwnerKey(ownerKey, ownerPad, strength128Bits); //userPad will be set in this.ownerKey
setupGlobalEncryptionKey(documentID, userPad, ownerKey, permissions, strength128Bits); //step 3
setupUserKey();
}
public void prepareKey() {
prepareRC4Key(key, 0, keySize);
}
public void setHashKey(int number, int generation) {
md5.reset(); //added by ujihara
extra[0] = (byte)number;
extra[1] = (byte)(number >> 8);
extra[2] = (byte)(number >> 16);
extra[3] = (byte)generation;
extra[4] = (byte)(generation >> 8);
md5.update(mkey);
key = md5.digest(extra);
keySize = mkey.length + 5;
if (keySize > 16)
keySize = 16;
}
public static PdfObject createInfoId(byte id[]) {
ByteBuffer buf = new ByteBuffer(90);
buf.append('[').append('<');
for (int k = 0; k < 16; ++k)
buf.appendHex(id[k]);
buf.append('>').append('<');
for (int k = 0; k < 16; ++k)
buf.appendHex(id[k]);
buf.append('>').append(']');
return new PdfLiteral(buf.toByteArray());
}
public PdfDictionary getEncryptionDictionary() {
PdfDictionary dic = new PdfDictionary();
dic.put(PdfName.FILTER, PdfName.STANDARD);
dic.put(PdfName.O, new PdfLiteral(PdfContentByte.escapeString(ownerKey)));
dic.put(PdfName.U, new PdfLiteral(PdfContentByte.escapeString(userKey)));
dic.put(PdfName.P, new PdfNumber(permissions));
if (mkey.length > 5) {
dic.put(PdfName.V, new PdfNumber(2));
dic.put(PdfName.R, new PdfNumber(3));
dic.put(PdfName.LENGTH, new PdfNumber(128));
}
else {
dic.put(PdfName.V, new PdfNumber(1));
dic.put(PdfName.R, new PdfNumber(2));
}
return dic;
}
public void prepareRC4Key(byte key[]) {
prepareRC4Key(key, 0, key.length);
}
public void prepareRC4Key(byte key[], int off, int len) {
int index1 = 0;
int index2 = 0;
for (int k = 0; k < 256; ++k)
state[k] = (byte)k;
x = 0;
y = 0;
byte tmp;
for (int k = 0; k < 256; ++k) {
index2 = (key[index1 + off] + state[k] + index2) & 255;
tmp = state[k];
state[k] = state[index2];
state[index2] = tmp;
index1 = (index1 + 1) % len;
}
}
public void encryptRC4(byte dataIn[], int off, int len, byte dataOut[]) {
int length = len + off;
byte tmp;
for (int k = off; k < length; ++k) {
x = (x + 1) & 255;
y = (state[x] + y) & 255;
tmp = state[x];
state[x] = state[y];
state[y] = tmp;
dataOut[k] = (byte)(dataIn[k] ^ state[(state[x] + state[y]) & 255]);
}
}
public void encryptRC4(byte data[], int off, int len) {
encryptRC4(data, off, len, data);
}
public void encryptRC4(byte dataIn[], byte dataOut[]) {
encryptRC4(dataIn, 0, dataIn.length, dataOut);
}
public void encryptRC4(byte data[]) {
encryptRC4(data, 0, data.length, data);
}
public PdfObject getFileID() {
return createInfoId(documentID);
}
}
