pdfencryption.java

非常有用的操作pdf文件的java源码

/**
 * Copyright (c) 2003-2005, 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.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.pdfbox.exceptions.CryptographyException;

/**
 * This class will deal with PDF encryption algorithms.
 *
 * @author <a href="mailto:[e-mail]">Ben Litchfield</a>
 * @version $Revision: 1.15 $
 * 
 * @deprecated use the new security layer instead
 * 
 * @see org.pdfbox.pdmodel.encryption.StandardSecurityHandler
 */
public final class PDFEncryption
{
    private ARCFour rc4 = new ARCFour();
    /**
     * The encryption padding defined in the PDF 1.4 Spec algorithm 3.2.
     */
    public static final byte[] ENCRYPT_PADDING =
    {
        (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
    };

    /**
     * This will encrypt a piece of data.
     *
     * @param objectNumber The id for the object.
     * @param genNumber The generation id for the object.
     * @param key The key used to encrypt the data.
     * @param data The data to encrypt/decrypt.
     * @param output The stream to write to.
     *
     * @throws CryptographyException If there is an error encrypting the data.
     * @throws IOException If there is an io error.
     */
    public final void encryptData(
        long objectNumber,
        long genNumber,
        byte[] key,
        InputStream data,
        OutputStream output )
        throws CryptographyException, IOException
    {
        byte[] newKey = new byte[ key.length + 5 ];
        System.arraycopy( key, 0, newKey, 0, key.length );
        //PDF 1.4 reference pg 73
        //step 1
        //we have the reference

        //step 2
        newKey[newKey.length -5] = (byte)(objectNumber & 0xff);
        newKey[newKey.length -4] = (byte)((objectNumber >> 8) & 0xff);
        newKey[newKey.length -3] = (byte)((objectNumber >> 16) & 0xff);
        newKey[newKey.length -2] = (byte)(genNumber & 0xff);
        newKey[newKey.length -1] = (byte)((genNumber >> 8) & 0xff);


        //step 3
        byte[] digestedKey = null;
        try
        {
            MessageDigest md = MessageDigest.getInstance( "MD5" );
            digestedKey = md.digest( newKey );
        }
        catch( NoSuchAlgorithmException e )
        {
            throw new CryptographyException( e );
        }

        //step 4
        int length = Math.min( newKey.length, 16 );
        byte[] finalKey = new byte[ length ];
        System.arraycopy( digestedKey, 0, finalKey, 0, length );

        rc4.setKey( finalKey );
        rc4.write( data, output );
        output.flush();
    }

    /**
     * This will get the user password from the owner password and the documents o value.
     *
     * @param ownerPassword The plaintext owner password.
     * @param o The document's o entry.
     * @param revision The document revision number.
     * @param length The length of the encryption.
     *
     * @return The plaintext padded user password.
     *
     * @throws CryptographyException If there is an error getting the user password.
     * @throws IOException If there is an error reading data.
     */
    public final byte[] getUserPassword(
        byte[] ownerPassword,
        byte[] o,
        int revision,
        long length )
        throws CryptographyException, IOException
    {
        try
        {
            ByteArrayOutputStream result = new ByteArrayOutputStream();

            //3.3 STEP 1
            byte[] ownerPadded = truncateOrPad( ownerPassword );

            //3.3 STEP 2
            MessageDigest md = MessageDigest.getInstance( "MD5" );
            md.update( ownerPadded );
            byte[] digest = md.digest();

            //3.3 STEP 3
            if( revision == 3 || revision == 4 )
            {
                for( int i=0; i<50; i++ )
                {
                    md.reset();
                    md.update( digest );
                    digest = md.digest();
                }
            }
            if( revision == 2 && length != 5 )
            {
                throw new CryptographyException(
                    "Error: Expected length=5 actual=" + length );
            }

            //3.3 STEP 4
            byte[] rc4Key = new byte[ (int)length ];
            System.arraycopy( digest, 0, rc4Key, 0, (int)length );

            //3.7 step 2
            if( revision == 2 )
            {
                rc4.setKey( rc4Key );
                rc4.write( o, result );
            }
            else if( revision == 3 || revision == 4)
            {
                /**
                byte[] iterationKey = new byte[ rc4Key.length ];
                byte[] dataToEncrypt = o;
                for( int i=19; i>=0; i-- )
                {
                    System.arraycopy( rc4Key, 0, iterationKey, 0, rc4Key.length );
                    for( int j=0; j< iterationKey.length; j++ )
                    {
                        iterationKey[j] = (byte)(iterationKey[j] ^ (byte)i);
                    }
                    rc4.setKey( iterationKey );
                    rc4.write( dataToEncrypt, result );
                    dataToEncrypt = result.toByteArray();
                    result.reset();
                }
                result.write( dataToEncrypt, 0, dataToEncrypt.length );
                */
                byte[] iterationKey = new byte[ rc4Key.length ];
                
              
                byte[] otemp = new byte[ o.length ]; //sm 
                System.arraycopy( o, 0, otemp, 0, o.length ); //sm
                rc4.write( o, result);//sm
                
                for( int i=19; i>=0; i-- )
                {
                    System.arraycopy( rc4Key, 0, iterationKey, 0, rc4Key.length );
                    for( int j=0; j< iterationKey.length; j++ )
                    {
                        iterationKey[j] = (byte)(iterationKey[j] ^ (byte)i);
                    }
                    rc4.setKey( iterationKey );
                    result.reset();  //sm
                    rc4.write( otemp, result ); //sm
                    otemp = result.toByteArray(); //sm                
                }
            }


            return result.toByteArray();

        }
        catch( NoSuchAlgorithmException e )
        {
            throw new CryptographyException( e );
        }
    }

    /**
     * This will tell if this is the owner password or not.
     *
     * @param ownerPassword The plaintext owner password.
     * @param u The U value from the PDF Document.
     * @param o The owner password hash.
     * @param permissions The document permissions.
     * @param id The document id.
     * @param revision The revision of the encryption.
     * @param length The length of the encryption key.
     *
     * @return true if the owner password matches the one from the document.
     *
     * @throws CryptographyException If there is an error while executing crypt functions.
     * @throws IOException If there is an error while checking owner password.
     */
    public final boolean isOwnerPassword(
        byte[] ownerPassword,
        byte[] u,
        byte[] o,
        int permissions,
        byte[] id,
        int revision,
        int length)
        throws CryptographyException, IOException
    {
        byte[] userPassword = getUserPassword( ownerPassword, o, revision, length );
        return isUserPassword( userPassword, u, o, permissions, id, revision, length );
    }

    /**
     * This will tell if this is a valid user password.
     *
     * Algorithm 3.6 pg 80
     *
     * @param password The password to test.
     * @param u The U value from the PDF Document.
     * @param o The owner password hash.
     * @param permissions The document permissions.
     * @param id The document id.
     * @param revision The revision of the encryption.
     * @param length The length of the encryption key.
     *
     * @return true If this is the correct user password.
     *
     * @throws CryptographyException If there is an error computing the value.
     * @throws IOException If there is an IO error while computing the owners password.
     */
    public final boolean isUserPassword(
        byte[] password,
        byte[] u,
        byte[] o,
        int permissions,
        byte[] id,
        int revision,
        int length)
        throws CryptographyException, IOException
    {
        boolean matches = false;
        //STEP 1
        byte[] computedValue = computeUserPassword( password, o, permissions, id, revision, length );
        if( revision == 2 )
        {
            //STEP 2
            matches = arraysEqual( u, computedValue );
        }
        else if( revision == 3 || revision == 4 )
        {