diff options
Diffstat (limited to 'src/main/java/org/pdfbox/encryption/PDFEncryption.java')
| -rw-r--r-- | src/main/java/org/pdfbox/encryption/PDFEncryption.java | 599 |
1 files changed, 599 insertions, 0 deletions
diff --git a/src/main/java/org/pdfbox/encryption/PDFEncryption.java b/src/main/java/org/pdfbox/encryption/PDFEncryption.java new file mode 100644 index 0000000..5bd3d64 --- /dev/null +++ b/src/main/java/org/pdfbox/encryption/PDFEncryption.java @@ -0,0 +1,599 @@ +/**
+ * 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 Ben Litchfield (ben@benlitchfield.com)
+ * @version $Revision: 1.13 $
+ */
+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 )
+ {
+ //STEP 2
+ matches = arraysEqual( u, computedValue, 16 );
+ }
+ return matches;
+ }
+
+ /**
+ * This will compare two byte[] for equality for count number of bytes.
+ *
+ * @param first The first byte array.
+ * @param second The second byte array.
+ * @param count The number of bytes to compare.
+ *
+ * @return true If the arrays contain the exact same data.
+ */
+ private final boolean arraysEqual( byte[] first, byte[] second, int count )
+ {
+ boolean equal = first.length >= count && second.length >= count;
+ for( int i=0; i<count && equal; i++ )
+ {
+ equal = first[i] == second[i];
+ }
+ return equal;
+ }
+
+ /**
+ * This will compare two byte[] for equality.
+ *
+ * @param first The first byte array.
+ * @param second The second byte array.
+ *
+ * @return true If the arrays contain the exact same data.
+ */
+ private final boolean arraysEqual( byte[] first, byte[] second )
+ {
+ boolean equal = first.length == second.length;
+ for( int i=0; i<first.length && equal; i++ )
+ {
+ equal = first[i] == second[i];
+ }
+ return equal;
+ }
+
+ /**
+ * This will compute the user password hash.
+ *
+ * @param password The plain text password.
+ * @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 The user password.
+ *
+ * @throws CryptographyException If there is an error computing the user password.
+ * @throws IOException If there is an IO error.
+ */
+ public final byte[] computeUserPassword(
+ byte[] password,
+ byte[] o,
+ int permissions,
+ byte[] id,
+ int revision,
+ int length )
+ throws CryptographyException, IOException
+ {
+ ByteArrayOutputStream result = new ByteArrayOutputStream();
+ //STEP 1
+ byte[] encryptionKey = computeEncryptedKey( password, o, permissions, id, revision, length );
+
+ if( revision == 2 )
+ {
+ //STEP 2
+ rc4.setKey( encryptionKey );
+ rc4.write( ENCRYPT_PADDING, result );
+ }
+ else if( revision == 3 || revision == 4 )
+ {
+ try
+ {
+ //STEP 2
+ MessageDigest md = MessageDigest.getInstance("MD5");
+ //md.update( truncateOrPad( password ) );
+ md.update( ENCRYPT_PADDING );
+
+ //STEP 3
+ md.update( id );
+ result.write( md.digest() );
+
+ //STEP 4 and 5
+ byte[] iterationKey = new byte[ encryptionKey.length ];
+ for( int i=0; i<20; i++ )
+ {
+ System.arraycopy( encryptionKey, 0, iterationKey, 0, iterationKey.length );
+ for( int j=0; j< iterationKey.length; j++ )
+ {
+ iterationKey[j] = (byte)(iterationKey[j] ^ i);
+ }
+ rc4.setKey( iterationKey );
+ ByteArrayInputStream input = new ByteArrayInputStream( result.toByteArray() );
+ result.reset();
+ rc4.write( input, result );
+ }
+
+ //step 6
+ byte[] finalResult = new byte[32];
+ System.arraycopy( result.toByteArray(), 0, finalResult, 0, 16 );
+ System.arraycopy( ENCRYPT_PADDING, 0, finalResult, 16, 16 );
+ result.reset();
+ result.write( finalResult );
+ }
+ catch( NoSuchAlgorithmException e )
+ {
+ throw new CryptographyException( e );
+ }
+ }
+ return result.toByteArray();
+ }
+
+ /**
+ * This will compute the encrypted key.
+ *
+ * @param password The password used to compute the encrypted key.
+ * @param o The owner password hash.
+ * @param permissions The permissions for the document.
+ * @param id The document id.
+ * @param revision The security revision.
+ * @param length The length of the encryption key.
+ *
+ * @return The encryption key.
+ *
+ * @throws CryptographyException If there is an error computing the key.
+ */
+ public final byte[] computeEncryptedKey(
+ byte[] password,
+ byte[] o,
+ int permissions,
+ byte[] id,
+ int revision,
+ int length )
+ throws CryptographyException
+ {
+ byte[] result = new byte[ length ];
+ try
+ {
+ //PDFReference 1.4 pg 78
+ //step1
+ byte[] padded = truncateOrPad( password );
+
+ //step 2
+ MessageDigest md = MessageDigest.getInstance("MD5");
+ md.update( padded );
+
+ //step 3
+ md.update( o );
+
+ //step 4
+ byte zero = (byte)(permissions >>> 0);
+ byte one = (byte)(permissions >>> 8);
+ byte two = (byte)(permissions >>> 16);
+ byte three = (byte)(permissions >>> 24);
+
+ md.update( zero );
+ md.update( one );
+ md.update( two );
+ md.update( three );
+
+ //step 5
+ md.update( id );
+ byte[] digest = md.digest();
+
+ //step 6
+ if( revision == 3 || revision == 4)
+ {
+ for( int i=0; i<50; i++ )
+ {
+ md.reset();
+ md.update( digest, 0, length );
+ digest = md.digest();
+ }
+ }
+
+ //step 7
+ if( revision == 2 && length != 5 )
+ {
+ throw new CryptographyException(
+ "Error: length should be 5 when revision is two actual=" + length );
+ }
+ System.arraycopy( digest, 0, result, 0, length );
+ }
+ catch( NoSuchAlgorithmException e )
+ {
+ throw new CryptographyException( e );
+ }
+ return result;
+ }
+
+ /**
+ * This algorithm is taked from PDF Reference 1.4 Algorithm 3.3 Page 79.
+ *
+ * @param ownerPassword The plain owner password.
+ * @param userPassword The plain user password.
+ * @param revision The version of the security.
+ * @param length The length of the document.
+ *
+ * @return The computed owner password.
+ *
+ * @throws CryptographyException If there is an error computing O.
+ * @throws IOException If there is an error computing O.
+ */
+ public final byte[] computeOwnerPassword(
+ byte[] ownerPassword,
+ byte[] userPassword,
+ int revision,
+ int length )
+ throws CryptographyException, IOException
+ {
+ try
+ {
+ //STEP 1
+ byte[] ownerPadded = truncateOrPad( ownerPassword );
+
+ //STEP 2
+ MessageDigest md = MessageDigest.getInstance( "MD5" );
+ md.update( ownerPadded );
+ byte[] digest = md.digest();
+
+ //STEP 3
+ if( revision == 3 || revision == 4)
+ {
+ for( int i=0; i<50; i++ )
+ {
+ md.reset();
+ md.update( digest, 0, length );
+ digest = md.digest();
+ }
+ }
+ if( revision == 2 && length != 5 )
+ {
+ throw new CryptographyException(
+ "Error: Expected length=5 actual=" + length );
+ }
+
+ //STEP 4
+ byte[] rc4Key = new byte[ length ];
+ System.arraycopy( digest, 0, rc4Key, 0, length );
+
+ //STEP 5
+ byte[] paddedUser = truncateOrPad( userPassword );
+
+
+ //STEP 6
+ rc4.setKey( rc4Key );
+ ByteArrayOutputStream crypted = new ByteArrayOutputStream();
+ rc4.write( new ByteArrayInputStream( paddedUser ), crypted );
+
+
+ //STEP 7
+ if( revision == 3 || revision == 4 )
+ {
+ byte[] iterationKey = new byte[ rc4Key.length ];
+ for( int i=1; i<20; 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 );
+ ByteArrayInputStream input = new ByteArrayInputStream( crypted.toByteArray() );
+ crypted.reset();
+ rc4.write( input, crypted );
+ }
+ }
+
+ //STEP 8
+ return crypted.toByteArray();
+ }
+ catch( NoSuchAlgorithmException e )
+ {
+ throw new CryptographyException( e.getMessage() );
+ }
+ }
+
+ /**
+ * This will take the password and truncate or pad it as necessary.
+ *
+ * @param password The password to pad or truncate.
+ *
+ * @return The padded or truncated password.
+ */
+ private final byte[] truncateOrPad( byte[] password )
+ {
+ byte[] padded = new byte[ ENCRYPT_PADDING.length ];
+ int bytesBeforePad = Math.min( password.length, padded.length );
+ System.arraycopy( password, 0, padded, 0, bytesBeforePad );
+ System.arraycopy( ENCRYPT_PADDING, 0, padded, bytesBeforePad, ENCRYPT_PADDING.length-bytesBeforePad );
+ return padded;
+ }
+}
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