546 lines
21 KiB
C#
546 lines
21 KiB
C#
using System;
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using System.Collections;
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using System.Security.Cryptography;
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using System.Text;
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using System.IO;
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using iTextSharp.text.pdf.crypto;
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using Org.BouncyCastle.X509;
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/*
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* $Id: PdfEncryption.cs,v 1.13 2007/06/14 20:01:48 psoares33 Exp $
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*
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* Copyright 2001-2006 Paulo Soares
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*
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* The contents of this file are subject to the Mozilla Public License Version 1.1
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* (the "License"); you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the License.
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*
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* The Original Code is 'iText, a free JAVA-PDF library'.
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*
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* The Initial Developer of the Original Code is Bruno Lowagie. Portions created by
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* the Initial Developer are Copyright (C) 1999, 2000, 2001, 2002 by Bruno Lowagie.
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* All Rights Reserved.
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* Co-Developer of the code is Paulo Soares. Portions created by the Co-Developer
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* are Copyright (C) 2000, 2001, 2002 by Paulo Soares. All Rights Reserved.
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*
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* Contributor(s): all the names of the contributors are added in the source code
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* where applicable.
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*
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* Alternatively, the contents of this file may be used under the terms of the
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* LGPL license (the "GNU LIBRARY GENERAL PUBLIC LICENSE"), in which case the
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* provisions of LGPL are applicable instead of those above. If you wish to
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* allow use of your version of this file only under the terms of the LGPL
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* License and not to allow others to use your version of this file under
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* the MPL, indicate your decision by deleting the provisions above and
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* replace them with the notice and other provisions required by the LGPL.
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* If you do not delete the provisions above, a recipient may use your version
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* of this file under either the MPL or the GNU LIBRARY GENERAL PUBLIC LICENSE.
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*
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* This library is free software; you can redistribute it and/or modify it
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* under the terms of the MPL as stated above or under the terms of the GNU
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* Library General Public License as published by the Free Software Foundation;
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* either version 2 of the License, or any later version.
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*
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* This library is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU Library general Public License for more
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* details.
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*
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* If you didn't download this code from the following link, you should check if
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* you aren't using an obsolete version:
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* http://www.lowagie.com/iText/
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*/
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namespace iTextSharp.text.pdf {
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/**
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*
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* @author Paulo Soares (psoares@consiste.pt)
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*/
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public class PdfEncryption {
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public const int STANDARD_ENCRYPTION_40 = 2;
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public const int STANDARD_ENCRYPTION_128 = 3;
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public const int AES_128 = 4;
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private static byte[] pad = {
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(byte)0x28, (byte)0xBF, (byte)0x4E, (byte)0x5E, (byte)0x4E, (byte)0x75,
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(byte)0x8A, (byte)0x41, (byte)0x64, (byte)0x00, (byte)0x4E, (byte)0x56,
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(byte)0xFF, (byte)0xFA, (byte)0x01, (byte)0x08, (byte)0x2E, (byte)0x2E,
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(byte)0x00, (byte)0xB6, (byte)0xD0, (byte)0x68, (byte)0x3E, (byte)0x80,
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(byte)0x2F, (byte)0x0C, (byte)0xA9, (byte)0xFE, (byte)0x64, (byte)0x53,
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(byte)0x69, (byte)0x7A};
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private static readonly byte[] salt = {(byte)0x73, (byte)0x41, (byte)0x6c, (byte)0x54};
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internal static readonly byte[] metadataPad = {(byte)255,(byte)255,(byte)255,(byte)255};
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/** The encryption key for a particular object/generation */
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internal byte[] key;
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/** The encryption key length for a particular object/generation */
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internal int keySize;
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/** The global encryption key */
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internal byte[] mkey;
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/** Work area to prepare the object/generation bytes */
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internal byte[] extra = new byte[5];
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/** The message digest algorithm MD5 */
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internal MD5 md5;
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/** The encryption key for the owner */
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internal byte[] ownerKey = new byte[32];
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/** The encryption key for the user */
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internal byte[] userKey = new byte[32];
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/** The public key security handler for certificate encryption */
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protected PdfPublicKeySecurityHandler publicKeyHandler = null;
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internal int permissions;
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internal byte[] documentID;
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internal static long seq = DateTime.Now.Ticks + Environment.TickCount;
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private int revision;
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private ARCFOUREncryption rc4 = new ARCFOUREncryption();
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/** The generic key length. It may be 40 or 128. */
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private int keyLength;
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private bool encryptMetadata;
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/**
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* Indicates if the encryption is only necessary for embedded files.
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* @since 2.1.3
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*/
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private bool embeddedFilesOnly;
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private int cryptoMode;
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public PdfEncryption() {
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md5 = new MD5CryptoServiceProvider();
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publicKeyHandler = new PdfPublicKeySecurityHandler();
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}
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public PdfEncryption(PdfEncryption enc) : this() {
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mkey = (byte[])enc.mkey.Clone();
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ownerKey = (byte[])enc.ownerKey.Clone();
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userKey = (byte[])enc.userKey.Clone();
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permissions = enc.permissions;
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if (enc.documentID != null)
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documentID = (byte[])enc.documentID.Clone();
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revision = enc.revision;
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keyLength = enc.keyLength;
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encryptMetadata = enc.encryptMetadata;
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embeddedFilesOnly = enc.embeddedFilesOnly;
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publicKeyHandler = enc.publicKeyHandler;
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}
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public void SetCryptoMode(int mode, int kl) {
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cryptoMode = mode;
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encryptMetadata = (mode & PdfWriter.DO_NOT_ENCRYPT_METADATA) == 0;
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embeddedFilesOnly = (mode & PdfWriter.EMBEDDED_FILES_ONLY) != 0;
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mode &= PdfWriter.ENCRYPTION_MASK;
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switch (mode) {
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case PdfWriter.STANDARD_ENCRYPTION_40:
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encryptMetadata = true;
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embeddedFilesOnly = false;
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keyLength = 40;
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revision = STANDARD_ENCRYPTION_40;
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break;
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case PdfWriter.STANDARD_ENCRYPTION_128:
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embeddedFilesOnly = false;
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if (kl > 0)
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keyLength = kl;
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else
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keyLength = 128;
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revision = STANDARD_ENCRYPTION_128;
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break;
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case PdfWriter.ENCRYPTION_AES_128:
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keyLength = 128;
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revision = AES_128;
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break;
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default:
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throw new ArgumentException("No valid encryption mode");
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}
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}
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public int GetCryptoMode() {
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return cryptoMode;
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}
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public bool IsMetadataEncrypted() {
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return encryptMetadata;
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}
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/**
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* Indicates if only the embedded files have to be encrypted.
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* @return if true only the embedded files will be encrypted
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* @since 2.1.3
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*/
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public bool IsEmbeddedFilesOnly() {
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return embeddedFilesOnly;
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}
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private byte[] PadPassword(byte[] userPassword) {
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byte[] userPad = new byte[32];
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if (userPassword == null) {
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Array.Copy(pad, 0, userPad, 0, 32);
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}
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else {
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Array.Copy(userPassword, 0, userPad, 0, Math.Min(userPassword.Length, 32));
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if (userPassword.Length < 32)
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Array.Copy(pad, 0, userPad, userPassword.Length, 32 - userPassword.Length);
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}
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return userPad;
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}
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/**
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*/
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private byte[] ComputeOwnerKey(byte[] userPad, byte[] ownerPad) {
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byte[] ownerKey = new byte[32];
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byte[] digest = md5.ComputeHash(ownerPad);
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if (revision == STANDARD_ENCRYPTION_128 || revision == AES_128) {
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byte[] mkey = new byte[keyLength / 8];
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// only use for the input as many bit as the key consists of
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for (int k = 0; k < 50; ++k)
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Array.Copy(md5.ComputeHash(digest), 0, digest, 0, mkey.Length);
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Array.Copy(userPad, 0, ownerKey, 0, 32);
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for (int i = 0; i < 20; ++i) {
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for (int j = 0; j < mkey.Length ; ++j)
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mkey[j] = (byte)(digest[j] ^ i);
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rc4.PrepareARCFOURKey(mkey);
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rc4.EncryptARCFOUR(ownerKey);
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}
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}
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else {
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rc4.PrepareARCFOURKey(digest, 0, 5);
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rc4.EncryptARCFOUR(userPad, ownerKey);
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}
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return ownerKey;
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}
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/**
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*
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* ownerKey, documentID must be setuped
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*/
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private void SetupGlobalEncryptionKey(byte[] documentID, byte[] userPad, byte[] ownerKey, int permissions) {
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this.documentID = documentID;
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this.ownerKey = ownerKey;
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this.permissions = permissions;
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// use variable keylength
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mkey = new byte[keyLength / 8];
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//fixed by ujihara in order to follow PDF refrence
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md5.Initialize();
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md5.TransformBlock(userPad, 0, userPad.Length, userPad, 0);
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md5.TransformBlock(ownerKey, 0, ownerKey.Length, ownerKey, 0);
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byte[] ext = new byte[4];
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ext[0] = (byte)permissions;
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ext[1] = (byte)(permissions >> 8);
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ext[2] = (byte)(permissions >> 16);
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ext[3] = (byte)(permissions >> 24);
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md5.TransformBlock(ext, 0, 4, ext, 0);
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if (documentID != null)
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md5.TransformBlock(documentID, 0, documentID.Length, documentID, 0);
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if (!encryptMetadata)
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md5.TransformBlock(metadataPad, 0, metadataPad.Length, metadataPad, 0);
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md5.TransformFinalBlock(ext, 0, 0);
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byte[] digest = new byte[mkey.Length];
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Array.Copy(md5.Hash, 0, digest, 0, mkey.Length);
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md5.Initialize();
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// only use the really needed bits as input for the hash
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if (revision == STANDARD_ENCRYPTION_128 || revision == AES_128) {
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for (int k = 0; k < 50; ++k) {
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Array.Copy(md5.ComputeHash(digest), 0, digest, 0, mkey.Length);
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md5.Initialize();
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}
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}
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Array.Copy(digest, 0, mkey, 0, mkey.Length);
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}
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/**
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*
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* mkey must be setuped
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*/
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// use the revision to choose the setup method
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private void SetupUserKey() {
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if (revision == STANDARD_ENCRYPTION_128 || revision == AES_128) {
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md5.TransformBlock(pad, 0, pad.Length, pad, 0);
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md5.TransformFinalBlock(documentID, 0, documentID.Length);
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byte[] digest = md5.Hash;
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md5.Initialize();
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Array.Copy(digest, 0, userKey, 0, 16);
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for (int k = 16; k < 32; ++k)
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userKey[k] = 0;
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for (int i = 0; i < 20; ++i) {
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for (int j = 0; j < mkey.Length; ++j)
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digest[j] = (byte)(mkey[j] ^ i);
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rc4.PrepareARCFOURKey(digest, 0, mkey.Length);
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rc4.EncryptARCFOUR(userKey, 0, 16);
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}
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}
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else {
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rc4.PrepareARCFOURKey(mkey);
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rc4.EncryptARCFOUR(pad, userKey);
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}
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}
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// gets keylength and revision and uses revison to choose the initial values for permissions
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public void SetupAllKeys(byte[] userPassword, byte[] ownerPassword, int permissions) {
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if (ownerPassword == null || ownerPassword.Length == 0)
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ownerPassword = md5.ComputeHash(CreateDocumentId());
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md5.Initialize();
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permissions |= (int)((revision == STANDARD_ENCRYPTION_128 || revision == AES_128) ? (uint)0xfffff0c0 : (uint)0xffffffc0);
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permissions &= unchecked((int)0xfffffffc);
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//PDF refrence 3.5.2 Standard Security Handler, Algorithum 3.3-1
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//If there is no owner password, use the user password instead.
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byte[] userPad = PadPassword(userPassword);
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byte[] ownerPad = PadPassword(ownerPassword);
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this.ownerKey = ComputeOwnerKey(userPad, ownerPad);
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documentID = CreateDocumentId();
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SetupByUserPad(this.documentID, userPad, this.ownerKey, permissions);
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}
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public static byte[] CreateDocumentId() {
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MD5 md5 = new MD5CryptoServiceProvider();
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long time = DateTime.Now.Ticks + Environment.TickCount;
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long mem = GC.GetTotalMemory(false);
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String s = time + "+" + mem + "+" + (seq++);
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return md5.ComputeHash(Encoding.ASCII.GetBytes(s));
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}
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public void SetupByUserPassword(byte[] documentID, byte[] userPassword, byte[] ownerKey, int permissions) {
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SetupByUserPad(documentID, PadPassword(userPassword), ownerKey, permissions);
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}
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/**
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*/
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private void SetupByUserPad(byte[] documentID, byte[] userPad, byte[] ownerKey, int permissions) {
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SetupGlobalEncryptionKey(documentID, userPad, ownerKey, permissions);
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SetupUserKey();
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}
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/**
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*/
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public void SetupByOwnerPassword(byte[] documentID, byte[] ownerPassword, byte[] userKey, byte[] ownerKey, int permissions) {
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SetupByOwnerPad(documentID, PadPassword(ownerPassword), userKey, ownerKey, permissions);
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}
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private void SetupByOwnerPad(byte[] documentID, byte[] ownerPad, byte[] userKey, byte[] ownerKey, int permissions) {
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byte[] userPad = ComputeOwnerKey(ownerKey, ownerPad); //userPad will be set in this.ownerKey
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SetupGlobalEncryptionKey(documentID, userPad, ownerKey, permissions); //step 3
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SetupUserKey();
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}
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public void SetupByEncryptionKey(byte[] key, int keylength) {
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mkey = new byte[keylength/8];
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System.Array.Copy(key, 0, mkey, 0, mkey.Length);
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}
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public void SetHashKey(int number, int generation) {
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md5.Initialize(); //added by ujihara
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extra[0] = (byte)number;
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extra[1] = (byte)(number >> 8);
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extra[2] = (byte)(number >> 16);
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extra[3] = (byte)generation;
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extra[4] = (byte)(generation >> 8);
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md5.TransformBlock(mkey, 0, mkey.Length, mkey, 0);
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md5.TransformBlock(extra, 0, extra.Length, extra, 0);
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if (revision == AES_128)
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md5.TransformBlock(salt, 0, salt.Length, salt, 0);
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md5.TransformFinalBlock(extra, 0, 0);
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key = md5.Hash;
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md5.Initialize();
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keySize = mkey.Length + 5;
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if (keySize > 16)
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keySize = 16;
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}
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public static PdfObject CreateInfoId(byte[] id) {
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ByteBuffer buf = new ByteBuffer(90);
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buf.Append('[').Append('<');
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for (int k = 0; k < 16; ++k)
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buf.AppendHex(id[k]);
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buf.Append('>').Append('<');
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id = CreateDocumentId();
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for (int k = 0; k < 16; ++k)
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buf.AppendHex(id[k]);
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buf.Append('>').Append(']');
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return new PdfLiteral(buf.ToByteArray());
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}
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public PdfDictionary GetEncryptionDictionary() {
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PdfDictionary dic = new PdfDictionary();
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if (publicKeyHandler.GetRecipientsSize() > 0) {
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PdfArray recipients = null;
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dic.Put(PdfName.FILTER, PdfName.PUBSEC);
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dic.Put(PdfName.R, new PdfNumber(revision));
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recipients = publicKeyHandler.GetEncodedRecipients();
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if (revision == STANDARD_ENCRYPTION_40) {
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dic.Put(PdfName.V, new PdfNumber(1));
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dic.Put(PdfName.SUBFILTER, PdfName.ADBE_PKCS7_S4);
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dic.Put(PdfName.RECIPIENTS, recipients);
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}
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else if (revision == STANDARD_ENCRYPTION_128 && encryptMetadata) {
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dic.Put(PdfName.V, new PdfNumber(2));
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dic.Put(PdfName.LENGTH, new PdfNumber(128));
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dic.Put(PdfName.SUBFILTER, PdfName.ADBE_PKCS7_S4);
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dic.Put(PdfName.RECIPIENTS, recipients);
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}
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else {
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dic.Put(PdfName.R, new PdfNumber(AES_128));
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dic.Put(PdfName.V, new PdfNumber(4));
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dic.Put(PdfName.SUBFILTER, PdfName.ADBE_PKCS7_S5);
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PdfDictionary stdcf = new PdfDictionary();
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stdcf.Put(PdfName.RECIPIENTS, recipients);
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if (!encryptMetadata)
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stdcf.Put(PdfName.ENCRYPTMETADATA, PdfBoolean.PDFFALSE);
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if (revision == AES_128)
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stdcf.Put(PdfName.CFM, PdfName.AESV2);
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else
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stdcf.Put(PdfName.CFM, PdfName.V2);
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PdfDictionary cf = new PdfDictionary();
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cf.Put(PdfName.DEFAULTCRYPTFILER, stdcf);
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dic.Put(PdfName.CF, cf);
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if (embeddedFilesOnly) {
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dic.Put(PdfName.EFF, PdfName.DEFAULTCRYPTFILER);
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dic.Put(PdfName.STRF, PdfName.IDENTITY);
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dic.Put(PdfName.STMF, PdfName.IDENTITY);
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}
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else {
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dic.Put(PdfName.STRF, PdfName.DEFAULTCRYPTFILER);
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dic.Put(PdfName.STMF, PdfName.DEFAULTCRYPTFILER);
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}
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}
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SHA1 sh = new SHA1CryptoServiceProvider();
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byte[] encodedRecipient = null;
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byte[] seed = publicKeyHandler.GetSeed();
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sh.TransformBlock(seed, 0, seed.Length, seed, 0);
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for (int i=0; i<publicKeyHandler.GetRecipientsSize(); i++)
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{
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encodedRecipient = publicKeyHandler.GetEncodedRecipient(i);
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sh.TransformBlock(encodedRecipient, 0, encodedRecipient.Length, encodedRecipient, 0);
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}
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if (!encryptMetadata)
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sh.TransformBlock(metadataPad, 0, metadataPad.Length, metadataPad, 0);
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sh.TransformFinalBlock(seed, 0, 0);
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byte[] mdResult = sh.Hash;
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SetupByEncryptionKey(mdResult, keyLength);
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} else {
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dic.Put(PdfName.FILTER, PdfName.STANDARD);
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dic.Put(PdfName.O, new PdfLiteral(PdfContentByte.EscapeString(ownerKey)));
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dic.Put(PdfName.U, new PdfLiteral(PdfContentByte.EscapeString(userKey)));
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dic.Put(PdfName.P, new PdfNumber(permissions));
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dic.Put(PdfName.R, new PdfNumber(revision));
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if (revision == STANDARD_ENCRYPTION_40) {
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dic.Put(PdfName.V, new PdfNumber(1));
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}
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else if (revision == STANDARD_ENCRYPTION_128 && encryptMetadata) {
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dic.Put(PdfName.V, new PdfNumber(2));
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dic.Put(PdfName.LENGTH, new PdfNumber(128));
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}
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else {
|
|
if (!encryptMetadata)
|
|
dic.Put(PdfName.ENCRYPTMETADATA, PdfBoolean.PDFFALSE);
|
|
dic.Put(PdfName.R, new PdfNumber(AES_128));
|
|
dic.Put(PdfName.V, new PdfNumber(4));
|
|
dic.Put(PdfName.LENGTH, new PdfNumber(128));
|
|
PdfDictionary stdcf = new PdfDictionary();
|
|
stdcf.Put(PdfName.LENGTH, new PdfNumber(16));
|
|
if (embeddedFilesOnly) {
|
|
stdcf.Put(PdfName.AUTHEVENT, PdfName.EFOPEN);
|
|
dic.Put(PdfName.EFF, PdfName.STDCF);
|
|
dic.Put(PdfName.STRF, PdfName.IDENTITY);
|
|
dic.Put(PdfName.STMF, PdfName.IDENTITY);
|
|
}
|
|
else {
|
|
stdcf.Put(PdfName.AUTHEVENT, PdfName.DOCOPEN);
|
|
dic.Put(PdfName.STRF, PdfName.STDCF);
|
|
dic.Put(PdfName.STMF, PdfName.STDCF);
|
|
}
|
|
if (revision == AES_128)
|
|
stdcf.Put(PdfName.CFM, PdfName.AESV2);
|
|
else
|
|
stdcf.Put(PdfName.CFM, PdfName.V2);
|
|
PdfDictionary cf = new PdfDictionary();
|
|
cf.Put(PdfName.STDCF, stdcf);
|
|
dic.Put(PdfName.CF, cf);
|
|
}
|
|
}
|
|
return dic;
|
|
}
|
|
|
|
public PdfObject FileID {
|
|
get {
|
|
return CreateInfoId(documentID);
|
|
}
|
|
}
|
|
public OutputStreamEncryption GetEncryptionStream(Stream os) {
|
|
return new OutputStreamEncryption(os, key, 0, keySize, revision);
|
|
}
|
|
|
|
public int CalculateStreamSize(int n) {
|
|
if (revision == AES_128)
|
|
return (n & 0x7ffffff0) + 32;
|
|
else
|
|
return n;
|
|
}
|
|
|
|
public byte[] EncryptByteArray(byte[] b) {
|
|
MemoryStream ba = new MemoryStream();
|
|
OutputStreamEncryption os2 = GetEncryptionStream(ba);
|
|
os2.Write(b, 0, b.Length);
|
|
os2.Finish();
|
|
return ba.ToArray();
|
|
}
|
|
|
|
public StandardDecryption GetDecryptor() {
|
|
return new StandardDecryption(key, 0, keySize, revision);
|
|
}
|
|
|
|
public byte[] DecryptByteArray(byte[] b) {
|
|
MemoryStream ba = new MemoryStream();
|
|
StandardDecryption dec = GetDecryptor();
|
|
byte[] b2 = dec.Update(b, 0, b.Length);
|
|
if (b2 != null)
|
|
ba.Write(b2, 0, b2.Length);
|
|
b2 = dec.Finish();
|
|
if (b2 != null)
|
|
ba.Write(b2, 0, b2.Length);
|
|
return ba.ToArray();
|
|
}
|
|
|
|
public void AddRecipient(X509Certificate cert, int permission) {
|
|
documentID = CreateDocumentId();
|
|
publicKeyHandler.AddRecipient(new PdfPublicKeyRecipient(cert, permission));
|
|
}
|
|
|
|
public byte[] ComputeUserPassword(byte[] ownerPassword) {
|
|
byte[] userPad = ComputeOwnerKey(ownerKey, PadPassword(ownerPassword));
|
|
for (int i = 0; i < userPad.Length; i++) {
|
|
bool match = true;
|
|
for (int j = 0; j < userPad.Length - i; j++) {
|
|
if (userPad[i + j] != pad[j]) {
|
|
match = false;
|
|
break;
|
|
}
|
|
}
|
|
if (!match) continue;
|
|
byte[] userPassword = new byte[i];
|
|
System.Array.Copy(userPad, 0, userPassword, 0, i);
|
|
return userPassword;
|
|
}
|
|
return userPad;
|
|
}
|
|
}
|
|
} |