package gnu.crypto.mode;
// ----------------------------------------------------------------------------
// $Id: BaseMode.java,v 1.7 2005/10/06 04:24:16 rsdio Exp $
//
// Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// GNU Crypto is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; see the file COPYING. If not, write to the
//
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// 51 Franklin Street, Fifth Floor,
// Boston, MA 02110-1301
// USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library. Thus, the terms and
// conditions of the GNU General Public License cover the whole
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//
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// you permission to link this library with independent modules to
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// ----------------------------------------------------------------------------
import gnu.crypto.cipher.IBlockCipher;
import java.security.InvalidKeyException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* <p>A basic abstract class to facilitate implementing block cipher modes of
* operations.</p>
*
* @version $Revision: 1.7 $
*/
public abstract class BaseMode implements IMode {
// Constants and variables
// -------------------------------------------------------------------------
/** The canonical name prefix of this mode. */
protected String name;
/** The state indicator of this instance. */
protected int state;
/** The underlying block cipher implementation. */
protected IBlockCipher cipher;
/** The block size, in bytes, to operate the underlying block cipher in. */
protected int cipherBlockSize;
/** The block size, in bytes, in which to operate the mode instance. */
protected int modeBlockSize;
/** The initialisation vector value. */
protected byte[] iv;
/** The instance lock. */
protected Object lock = new Object();
// Constructor(s)
// -------------------------------------------------------------------------
/**
* <p>Trivial constructor for use by concrete subclasses.</p>
*
* @param name the canonical name prefix of this mode.
* @param underlyingCipher the implementation of the underlying cipher.
* @param cipherBlockSize the block size, in bytes, in which to operate the
* underlying cipher.
*/
protected
BaseMode(String name, IBlockCipher underlyingCipher, int cipherBlockSize) {
super();
this.name = name;
this.cipher = underlyingCipher;
this.cipherBlockSize = cipherBlockSize;
state = -1;
}
// Class methods
// -------------------------------------------------------------------------
// Instance methods
// -------------------------------------------------------------------------
// IMode interface implementation ------------------------------------------
public void update(byte[] in, int inOffset, byte[] out, int outOffset)
throws IllegalStateException {
synchronized(lock) {
switch (state) {
case ENCRYPTION:
encryptBlock(in, inOffset, out, outOffset);
break;
case DECRYPTION:
decryptBlock(in, inOffset, out, outOffset);
break;
default:
throw new IllegalStateException();
}
}
}
// IBlockCipher interface implementation -----------------------------------
public String name() {
return new StringBuffer()
.append(name).append('(').append(cipher.name()).append(')')
.toString();
}
/**
* <p>Returns the default value, in bytes, of the mode's block size. This
* value is part of the construction arguments passed to the Factory methods
* in {@link ModeFactory}. Unless changed by an invocation of any of the
* <code>init()</code> methods, a <i>Mode</i> instance would operate with
* the same block size as its underlying block cipher. As mentioned earlier,
* the block size of the underlying block cipher itself is specified in one
* of the method(s) available in the factory class.</p>
*
* @return the default value, in bytes, of the mode's block size.
* @see gnu.crypto.mode.ModeFactory
*/
public int defaultBlockSize() {
return cipherBlockSize;
}
/**
* <p>Returns the default value, in bytes, of the underlying block cipher
* key size.</p>
*
* @return the default value, in bytes, of the underlying cipher's key size.
*/
public int defaultKeySize() {
return cipher.defaultKeySize();
}
/**
* <p>Returns an {@link Iterator} over the supported block sizes. Each
* element returned by this object is an {@link Integer}.</p>
*
* <p>The default behaviour is to return an iterator with just one value,
* which is that currently configured for the underlying block cipher.
* Concrete implementations may override this behaviour to signal their
* ability to support other values.</p>
*
* @return an {@link Iterator} over the supported block sizes.
*/
public Iterator blockSizes() {
ArrayList al = new ArrayList();
al.add(new Integer(cipherBlockSize));
return Collections.unmodifiableList(al).iterator();
}
/**
* <p>Returns an {@link Iterator} over the supported underlying block cipher
* key sizes. Each element returned by this object is an instance of
* {@link Integer}.</p>
*
* @return an {@link Iterator} over the supported key sizes.
*/
public Iterator keySizes() {
return cipher.keySizes();
}
public void init(Map attributes)
throws InvalidKeyException, IllegalStateException {
synchronized(lock) {
if (state != -1) {
throw new IllegalStateException();
}
Integer want = (Integer) attributes.get(STATE);
if (want != null) {
switch (want.intValue()) {
case ENCRYPTION: state = ENCRYPTION; break;
case DECRYPTION: state = DECRYPTION; break;
default: throw new IllegalArgumentException();
}
}
Integer bs = (Integer) attributes.get(MODE_BLOCK_SIZE);
modeBlockSize = (bs == null ? cipherBlockSize : bs.intValue());
byte[] iv = (byte[]) attributes.get(IV);
if (iv != null) {
this.iv = (byte[]) iv.clone();
} else {
this.iv = new byte[modeBlockSize];
}
cipher.init(attributes);
setup();
}
}
public int currentBlockSize() {
if (state == -1) {
throw new IllegalStateException();
}
return modeBlockSize;
}
public void reset() {
synchronized(lock) {
state = -1;
iv = null;
cipher.reset();
teardown();
}
}
public boolean selfTest() {
int ks;
Iterator bit;
for (Iterator kit = keySizes(); kit.hasNext(); ) {
ks = ((Integer) kit.next()).intValue();
for (bit = blockSizes(); bit.hasNext(); ) {
if (!testSymmetry(ks, ((Integer) bit.next()).intValue())) {
return false;
}
}
}
return true;
}
// methods to be implemented by concrete subclasses ------------------------
public abstract Object clone();
/** The initialisation phase of the concrete mode implementation. */
public abstract void setup();
/** The termination phase of the concrete mode implementation. */
public abstract void teardown();
public abstract void encryptBlock(byte[] in, int i, byte[] out, int o);
public abstract void decryptBlock(byte[] in, int i, byte[] out, int o);
// own methods -------------------------------------------------------------
private boolean testSymmetry(int ks, int bs) {
try {
IMode mode = (IMode) this.clone();
byte[] iv = new byte[cipherBlockSize]; // all zeroes
byte[] k = new byte[ks];
int i;
for (i = 0; i < ks; i++) {
k[i] = (byte) i;
}
int blockCount = 5;
int limit = blockCount * bs;
byte[] pt = new byte[limit];
for (i = 0; i < limit; i++) {
pt[i] = (byte) i;
}
byte[] ct = new byte[limit];
byte[] cpt = new byte[limit];
Map map = new HashMap();
map.put(KEY_MATERIAL, k);
map.put(CIPHER_BLOCK_SIZE, new Integer(cipherBlockSize));
map.put(STATE, new Integer(ENCRYPTION));
map.put(IV, iv);
map.put(MODE_BLOCK_SIZE, new Integer(bs));
mode.reset();
mode.init(map);
for (i = 0; i < blockCount; i++) {
mode.update(pt, i * bs, ct, i * bs);
}
mode.reset();
map.put(STATE, new Integer(DECRYPTION));
mode.init(map);
for (i = 0; i < blockCount; i++) {
mode.update(ct, i * bs, cpt, i * bs);
}
return Arrays.equals(pt, cpt);
} catch (Exception x) {
x.printStackTrace(System.err);
return false;
}
}
}