de.intarsys.pdf.crypt.StandardSecurityHandlerR4 Maven / Gradle / Ivy
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This is a fork of http://sourceforge.net/projects/jpodlib/ as development seems to be frozen.
We're providing some bug fixes along with deployments to maven.
/*
* Copyright (c) 2007, intarsys consulting GmbH
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - 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.
*
* - Neither the name of intarsys 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 COPYRIGHT OWNER 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.
*/
package de.intarsys.pdf.crypt;
import de.intarsys.pdf.cos.COSName;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import java.security.MessageDigest;
/**
* The {@link ISecurityHandler} implementing /R 4 of the PDF spec.
*/
public class StandardSecurityHandlerR4 extends StandardSecurityHandler {
public static final String KEY_ALGORITHM = "RC4"; //$NON-NLS-1$
public static final String CIPHER_ALGORITHM = "RC4"; //$NON-NLS-1$
public static final String DIGEST_ALGORITHM = "MD5"; //$NON-NLS-1$
public static final COSName DK_AuthEvent = COSName.constant("AuthEvent"); //$NON-NLS-1$
/**
* A byte sequence to be include in the hash under certain circumstances.
*/
private static byte[] HIGH_BYTES = {(byte) 0xFF, (byte) 0xFF, (byte) 0xFF, (byte) 0xFF};
@Override
public boolean authenticateOwner(byte[] owner) throws COSSecurityException {
try {
byte[] preparedOwner = prepareBytes(owner);
MessageDigest md = MessageDigest.getInstance(DIGEST_ALGORITHM);
md.update(preparedOwner);
byte[] key = md.digest();
for (int i = 0; i < 50; i++) {
md.update(key);
key = md.digest();
}
// this is not sufficiently specified in the PDF spec
// int length = getEncryption().getLength() / 8;
int length = 16;
byte[] encryptionKey = new byte[length];
System.arraycopy(key, 0, encryptionKey, 0, length);
//
Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
if (cipher == null) {
throw new COSSecurityException("RC4 cipher not found"); //$NON-NLS-1$
}
SecretKey skeySpec;
byte[] encrypted = getO();
byte[] tempEncKey = new byte[encryptionKey.length];
for (int i = 19; i >= 0; i--) {
for (int index = 0; index < encryptionKey.length; index++) {
tempEncKey[index] = (byte) (encryptionKey[index] ^ i);
}
skeySpec = new SecretKeySpec(tempEncKey, KEY_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
encrypted = cipher.doFinal(encrypted);
}
if (authenticateUser(encrypted)) {
setActiveAccessPermissions(AccessPermissionsFull.get());
return true;
}
return false;
} catch (Exception e) {
throw new COSSecurityException(e);
}
}
@Override
public boolean authenticateUser(byte[] user) throws COSSecurityException {
byte[] entryU = getU();
byte[] tempU = createUserPassword(user);
if (entryU.length != tempU.length) {
return false;
}
int length = 16;
for (int i = 0; i < length; i++) {
if (entryU[i] != tempU[i]) {
return false;
}
}
// if user is correctly authenticated, this key can be used for
// decryption
setCryptKey(createCryptKey(user));
setActiveAccessPermissions(createAccessPermissions());
return true;
}
@Override
protected IAccessPermissions createAccessPermissions() {
return new AccessPermissionsR3(getPermissionFlags());
}
@Override
protected byte[] createCryptKey(byte[] password) throws COSSecurityException {
try {
MessageDigest md = MessageDigest.getInstance(DIGEST_ALGORITHM);
byte[] prepared = prepareBytes(password);
md.update(prepared);
md.update(getO());
md.update(getPBytes());
byte[] fd = getPermanentFileID();
if (fd != null) {
md.update(fd);
}
if (!isEncryptMetadata()) {
md.update(HIGH_BYTES);
}
byte[] key = md.digest();
// this is not sufficiently specified in the PDF spec
// int length = getEncryption().getLength() / 8;
int length = 16;
for (int i = 0; i < 50; i++) {
md.update(key, 0, length);
key = md.digest();
}
byte[] result = new byte[length];
System.arraycopy(key, 0, result, 0, length);
return result;
} catch (Exception e) {
throw new COSSecurityException(e);
}
}
@Override
protected byte[] createOwnerPassword(byte[] owner, byte[] user) throws COSSecurityException {
try {
byte[] preparedOwner;
if (owner == null) {
preparedOwner = prepareBytes(user);
} else {
preparedOwner = prepareBytes(owner);
}
MessageDigest md = MessageDigest.getInstance(DIGEST_ALGORITHM);
md.update(preparedOwner);
byte[] key = md.digest();
// this is not sufficiently specified in the PDF spec
// int length = getEncryption().getLength() / 8;
int length = 16;
for (int i = 0; i < 50; i++) {
md.update(key, 0, length);
key = md.digest();
}
byte[] encryptionKey = new byte[length];
System.arraycopy(key, 0, encryptionKey, 0, length);
//
SecretKey skeySpec = new SecretKeySpec(encryptionKey, KEY_ALGORITHM);
byte[] preparedUser = prepareBytes(user);
Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(preparedUser);
byte[] tempKey = new byte[encryptionKey.length];
for (int i = 1; i <= 19; i++) {
for (int index = 0; index < encryptionKey.length; index++) {
tempKey[index] = (byte) (encryptionKey[index] ^ i);
}
skeySpec = new SecretKeySpec(tempKey, KEY_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
encrypted = cipher.doFinal(encrypted);
}
return encrypted;
} catch (Exception e) {
throw new COSSecurityException(e);
}
}
@Override
protected byte[] createUserPassword(byte[] user) throws COSSecurityException {
try {
byte[] encryptionKey = createCryptKey(user);
MessageDigest md = MessageDigest.getInstance(DIGEST_ALGORITHM);
md.update(PADDING);
byte[] fd = getPermanentFileID();
if (fd != null) {
md.update(fd);
}
byte[] hash = md.digest();
SecretKey skeySpec = new SecretKeySpec(encryptionKey, KEY_ALGORITHM);
Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(hash);
byte[] tempEncKey = new byte[encryptionKey.length];
for (int i = 1; i <= 19; i++) {
for (int index = 0; index < encryptionKey.length; index++) {
tempEncKey[index] = (byte) (encryptionKey[index] ^ i);
}
skeySpec = new SecretKeySpec(tempEncKey, KEY_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
encrypted = cipher.doFinal(encrypted);
}
byte[] result = new byte[32];
System.arraycopy(encrypted, 0, result, 0, 16);
System.arraycopy(USER_R3_PADDING, 0, result, 16, 16);
return result;
} catch (Exception e) {
throw new COSSecurityException(e);
}
}
@Override
public int getRevision() {
return 4;
}
}