From 6025b6016517c6d898d8957d1d7e03ba71431912 Mon Sep 17 00:00:00 2001
From: tknall <tknall@7b5415b0-85f9-ee4d-85bd-d5d0c3b42d1c>
Date: Fri, 1 Dec 2006 12:20:24 +0000
Subject: Initial import of release 2.2.

git-svn-id: https://joinup.ec.europa.eu/svn/pdf-as/trunk@4 7b5415b0-85f9-ee4d-85bd-d5d0c3b42d1c
---
 .../org/pdfbox/encryption/DocumentEncryption.java  | 427 +++++++++++++++++++++
 1 file changed, 427 insertions(+)
 create mode 100644 src/main/java/org/pdfbox/encryption/DocumentEncryption.java

(limited to 'src/main/java/org/pdfbox/encryption/DocumentEncryption.java')

diff --git a/src/main/java/org/pdfbox/encryption/DocumentEncryption.java b/src/main/java/org/pdfbox/encryption/DocumentEncryption.java
new file mode 100644
index 0000000..9ae6936
--- /dev/null
+++ b/src/main/java/org/pdfbox/encryption/DocumentEncryption.java
@@ -0,0 +1,427 @@
+/**
+ * Copyright (c) 2003-2004, www.pdfbox.org
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. Neither the name of pdfbox; nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * http://www.pdfbox.org
+ *
+ */
+package org.pdfbox.encryption;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.InputStream;
+import java.io.IOException;
+
+import java.math.BigInteger;
+
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+
+import org.pdfbox.exceptions.CryptographyException;
+import org.pdfbox.exceptions.InvalidPasswordException;
+
+import org.pdfbox.cos.COSArray;
+import org.pdfbox.cos.COSBase;
+import org.pdfbox.cos.COSDictionary;
+import org.pdfbox.cos.COSDocument;
+import org.pdfbox.cos.COSName;
+import org.pdfbox.cos.COSObject;
+import org.pdfbox.cos.COSStream;
+import org.pdfbox.cos.COSString;
+
+import org.pdfbox.pdmodel.PDDocument;
+
+import org.pdfbox.pdmodel.encryption.PDStandardEncryption;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+/**
+ * This class will deal with encrypting/decrypting a document.
+ *
+ * @author Ben Litchfield (ben@benlitchfield.com)
+ * @version $Revision: 1.10 $
+ */
+public class DocumentEncryption
+{
+    private PDDocument pdDocument = null;
+    private COSDocument document = null;
+
+    private byte[] encryptionKey = null;
+    private PDFEncryption encryption = new PDFEncryption();
+
+    private Set objects = new HashSet();
+    
+    /**
+     * A set that contains potential signature dictionaries.  This is used
+     * because the Contents entry of the signature is not encrypted.
+     */
+    private Set potentialSignatures = new HashSet();
+
+    /**
+     * Constructor.
+     *
+     * @param doc The document to decrypt.
+     */
+    public DocumentEncryption( PDDocument doc )
+    {
+        pdDocument = doc;
+        document = doc.getDocument();
+    }
+
+    /**
+     * Constructor.
+     *
+     * @param doc The document to decrypt.
+     */
+    public DocumentEncryption( COSDocument doc )
+    {
+        pdDocument = new PDDocument( doc );
+        document = doc;
+    }
+
+    /**
+     * This will encrypt the given document, given the owner password and user password.
+     * The encryption method used is the standard filter.
+     *
+     * @throws CryptographyException If an error occurs during encryption.
+     * @throws IOException If there is an error accessing the data.
+     */
+    public void initForEncryption()
+        throws CryptographyException, IOException
+    {
+        String ownerPassword = pdDocument.getOwnerPasswordForEncryption();
+        String userPassword = pdDocument.getUserPasswordForEncryption();
+        if( ownerPassword == null )
+        {
+            ownerPassword = "";
+        }
+        if( userPassword == null )
+        {
+            userPassword = "";
+        }
+        PDStandardEncryption encParameters = (PDStandardEncryption)pdDocument.getEncryptionDictionary();
+        int permissionInt = encParameters.getPermissions();
+        int revision = encParameters.getRevision();
+        int length = encParameters.getLength()/8;
+        COSArray idArray = document.getDocumentID();
+
+        //check if the document has an id yet.  If it does not then
+        //generate one
+        if( idArray == null || idArray.size() < 2 )
+        {
+            idArray = new COSArray();
+            try
+            {
+                MessageDigest md = MessageDigest.getInstance( "MD5" );
+                BigInteger time = BigInteger.valueOf( System.currentTimeMillis() );
+                md.update( time.toByteArray() );
+                md.update( ownerPassword.getBytes() );
+                md.update( userPassword.getBytes() );
+                md.update( document.toString().getBytes() );
+                byte[] id = md.digest( this.toString().getBytes() );
+                COSString idString = new COSString();
+                idString.append( id );
+                idArray.add( idString );
+                idArray.add( idString );
+                document.setDocumentID( idArray );
+            }
+            catch( NoSuchAlgorithmException e )
+            {
+                throw new CryptographyException( e );
+            }
+
+        }
+        COSString id = (COSString)idArray.getObject( 0 );
+        encryption = new PDFEncryption();
+
+        byte[] o = encryption.computeOwnerPassword(
+            ownerPassword.getBytes("ISO-8859-1"),
+            userPassword.getBytes("ISO-8859-1"), revision, length);
+
+        byte[] u = encryption.computeUserPassword(
+            userPassword.getBytes("ISO-8859-1"),
+            o, permissionInt, id.getBytes(), revision, length);
+
+        encryptionKey = encryption.computeEncryptedKey(
+            userPassword.getBytes("ISO-8859-1"), o, permissionInt, id.getBytes(), revision, length);
+
+        encParameters.setOwnerKey( o );
+        encParameters.setUserKey( u );
+        
+        document.setEncryptionDictionary( encParameters.getCOSDictionary() );
+    }
+    
+    
+
+    /**
+     * This will decrypt the document.
+     *
+     * @param password The password for the document.
+     *
+     * @throws CryptographyException If there is an error decrypting the document.
+     * @throws IOException If there is an error getting the stream data.
+     * @throws InvalidPasswordException If the password is not a user or owner password.
+     */
+    public void decryptDocument( String password )
+        throws CryptographyException, IOException, InvalidPasswordException
+    {
+        if( password == null )
+        {
+            password = "";
+        }
+
+        PDStandardEncryption encParameters = (PDStandardEncryption)pdDocument.getEncryptionDictionary();
+
+
+        int permissions = encParameters.getPermissions();
+        int revision = encParameters.getRevision();
+        int length = encParameters.getLength()/8;
+
+        COSString id = (COSString)document.getDocumentID().getObject( 0 );
+        byte[] u = encParameters.getUserKey();
+        byte[] o = encParameters.getOwnerKey();
+
+        boolean isUserPassword =
+            encryption.isUserPassword( password.getBytes(), u,
+                o, permissions, id.getBytes(), revision, length );
+        boolean isOwnerPassword =
+            encryption.isOwnerPassword( password.getBytes(), u,
+                o, permissions, id.getBytes(), revision, length );
+
+        if( isUserPassword )
+        {
+            encryptionKey =
+                encryption.computeEncryptedKey(
+                    password.getBytes(), o,
+                    permissions, id.getBytes(), revision, length );
+        }
+        else if( isOwnerPassword )
+        {
+            byte[] computedUserPassword =
+                encryption.getUserPassword(
+                    password.getBytes(),
+                    o,
+                    revision,
+                    length );
+            encryptionKey =
+                encryption.computeEncryptedKey(
+                    computedUserPassword, o,
+                    permissions, id.getBytes(), revision, length );
+        }
+        else
+        {
+            throw new InvalidPasswordException( "Error: The supplied password does not match " +
+                                                "either the owner or user password in the document." );
+        }
+        
+        COSDictionary trailer = document.getTrailer();
+        COSArray fields = (COSArray)trailer.getObjectFromPath( "Root/AcroForm/Fields" );
+        
+        //We need to collect all the signature dictionaries, for some
+        //reason the 'Contents' entry of signatures is not really encrypted
+        if( fields != null )
+        {
+            for( int i=0; i<fields.size(); i++ )
+            {
+                COSDictionary field = (COSDictionary)fields.getObject( i );
+                addDictionaryAndSubDictionary( potentialSignatures, field );
+            }
+        }
+
+        List allObjects = document.getObjects();
+        Iterator objectIter = allObjects.iterator();
+        while( objectIter.hasNext() )
+        {
+            decryptObject( (COSObject)objectIter.next() );
+        }
+        document.setEncryptionDictionary( null );
+    }
+    
+    private void addDictionaryAndSubDictionary( Set set, COSDictionary dic )
+    {
+        set.add( dic );
+        COSArray kids = (COSArray)dic.getDictionaryObject( "Kids" );
+        for( int i=0; kids != null && i<kids.size(); i++ )
+        {
+            addDictionaryAndSubDictionary( set, (COSDictionary)kids.getObject( i ) );
+        }
+        COSBase value = dic.getDictionaryObject( "V" );
+        if( value instanceof COSDictionary )
+        {
+            addDictionaryAndSubDictionary( set, (COSDictionary)value );
+        }
+    }
+
+    /**
+     * This will decrypt an object in the document.
+     *
+     * @param object The object to decrypt.
+     *
+     * @throws CryptographyException If there is an error decrypting the stream.
+     * @throws IOException If there is an error getting the stream data.
+     */
+    private void decryptObject( COSObject object )
+        throws CryptographyException, IOException
+    {
+        long objNum = object.getObjectNumber().intValue();
+        long genNum = object.getGenerationNumber().intValue();
+        COSBase base = object.getObject();
+        decrypt( base, objNum, genNum );
+    }
+
+    /**
+     * This will dispatch to the correct method.
+     *
+     * @param obj The object to decrypt.
+     * @param objNum The object number.
+     * @param genNum The object generation Number.
+     *
+     * @throws CryptographyException If there is an error decrypting the stream.
+     * @throws IOException If there is an error getting the stream data.
+     */
+    private void decrypt( Object obj, long objNum, long genNum )
+        throws CryptographyException, IOException
+    {
+        if( !objects.contains( obj ) )
+        {
+            objects.add( obj );
+
+            if( obj instanceof COSString )
+            {
+                decryptString( (COSString)obj, objNum, genNum );
+            }
+            else if( obj instanceof COSStream )
+            {
+                decryptStream( (COSStream)obj, objNum, genNum );
+            }
+            else if( obj instanceof COSDictionary )
+            {
+                decryptDictionary( (COSDictionary)obj, objNum, genNum );
+            }
+            else if( obj instanceof COSArray )
+            {
+                decryptArray( (COSArray)obj, objNum, genNum );
+            }
+        }
+    }
+
+    /**
+     * This will decrypt a stream.
+     *
+     * @param stream The stream to decrypt.
+     * @param objNum The object number.
+     * @param genNum The object generation number.
+     *
+     * @throws CryptographyException If there is an error getting the stream.
+     * @throws IOException If there is an error getting the stream data.
+     */
+    public void decryptStream( COSStream stream, long objNum, long genNum )
+        throws CryptographyException, IOException
+    {
+        decryptDictionary( stream, objNum, genNum );
+        InputStream encryptedStream = stream.getFilteredStream();
+        encryption.encryptData( objNum,
+                                genNum,
+                                encryptionKey,
+                                encryptedStream,
+                                stream.createFilteredStream() );
+    }
+
+    /**
+     * This will decrypt a dictionary.
+     *
+     * @param dictionary The dictionary to decrypt.
+     * @param objNum The object number.
+     * @param genNum The object generation number.
+     *
+     * @throws CryptographyException If there is an error decrypting the document.
+     * @throws IOException If there is an error creating a new string.
+     */
+    private void decryptDictionary( COSDictionary dictionary, long objNum, long genNum )
+        throws CryptographyException, IOException
+    {
+        Iterator keys = dictionary.keyList().iterator();
+        while( keys.hasNext() )
+        {
+            COSName key = (COSName)keys.next();
+            Object value = dictionary.getItem( key );
+            //if we are a signature dictionary and contain a Contents entry then
+            //we don't decrypt it.
+            if( !(key.getName().equals( "Contents" ) && 
+                  value instanceof COSString && 
+                  potentialSignatures.contains( dictionary )))
+            {
+                decrypt( value, objNum, genNum );
+            }
+        }
+    }
+
+    /**
+     * This will decrypt a string.
+     *
+     * @param string the string to decrypt.
+     * @param objNum The object number.
+     * @param genNum The object generation number.
+     *
+     * @throws CryptographyException If an error occurs during decryption.
+     * @throws IOException If an error occurs writing the new string.
+     */
+    public void decryptString( COSString string, long objNum, long genNum )
+        throws CryptographyException, IOException
+    {
+        ByteArrayInputStream data = new ByteArrayInputStream( string.getBytes() );
+        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+        encryption.encryptData( objNum,
+                                genNum,
+                                encryptionKey,
+                                data,
+                                buffer );
+        string.reset();
+        string.append( buffer.toByteArray() );
+    }
+
+    /**
+     * This will decrypt an array.
+     *
+     * @param array The array to decrypt.
+     * @param objNum The object number.
+     * @param genNum The object generation number.
+     *
+     * @throws CryptographyException If an error occurs during decryption.
+     * @throws IOException If there is an error accessing the data.
+     */
+    private void decryptArray( COSArray array, long objNum, long genNum )
+        throws CryptographyException, IOException
+    {
+        for( int i=0; i<array.size(); i++ )
+        {
+            decrypt( array.get( i ), objNum, genNum );
+        }
+    }
+}
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