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jeremybenn |
/* BaseMode.java --
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Copyright (C) 2001, 2002, 2003, 2006 Free Software Foundation, Inc.
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This file is a part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at
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your option) any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
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USA
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.javax.crypto.mode;
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import gnu.java.lang.CPStringBuilder;
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import gnu.javax.crypto.cipher.IBlockCipher;
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import java.security.InvalidKeyException;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.HashMap;
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import java.util.Iterator;
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import java.util.Map;
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/**
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* A basic abstract class to facilitate implementing block cipher modes of
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* operations.
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*/
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public abstract class BaseMode
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implements IMode
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{
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/** The canonical name prefix of this mode. */
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protected String name;
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/** The state indicator of this instance. */
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protected int state;
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/** The underlying block cipher implementation. */
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protected IBlockCipher cipher;
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/** The block size, in bytes, to operate the underlying block cipher in. */
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protected int cipherBlockSize;
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/** The block size, in bytes, in which to operate the mode instance. */
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protected int modeBlockSize;
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/** The initialisation vector value. */
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protected byte[] iv;
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/** The instance lock. */
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protected Object lock = new Object();
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/**
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* Trivial constructor for use by concrete subclasses.
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*
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* @param name the canonical name prefix of this mode.
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* @param underlyingCipher the implementation of the underlying cipher.
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* @param cipherBlockSize the block size, in bytes, in which to operate the
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* underlying cipher.
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*/
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protected BaseMode(String name, IBlockCipher underlyingCipher,
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int cipherBlockSize)
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{
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super();
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this.name = name;
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this.cipher = underlyingCipher;
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this.cipherBlockSize = cipherBlockSize;
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state = -1;
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}
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public void update(byte[] in, int inOffset, byte[] out, int outOffset)
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throws IllegalStateException
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{
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synchronized (lock)
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{
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switch (state)
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{
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case ENCRYPTION:
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encryptBlock(in, inOffset, out, outOffset);
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break;
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case DECRYPTION:
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decryptBlock(in, inOffset, out, outOffset);
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break;
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default:
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throw new IllegalStateException();
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}
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}
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}
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public String name()
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{
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return new CPStringBuilder(name).append('(').append(cipher.name()).append(')')
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.toString();
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}
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/**
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* Returns the default value, in bytes, of the mode's block size. This value
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* is part of the construction arguments passed to the Factory methods in
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* {@link ModeFactory}. Unless changed by an invocation of any of the
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* <code>init()</code> methods, a <i>Mode</i> instance would operate with
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* the same block size as its underlying block cipher. As mentioned earlier,
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* the block size of the underlying block cipher itself is specified in one of
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* the method(s) available in the factory class.
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*
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* @return the default value, in bytes, of the mode's block size.
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* @see ModeFactory
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*/
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public int defaultBlockSize()
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{
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return cipherBlockSize;
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}
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/**
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* Returns the default value, in bytes, of the underlying block cipher key
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* size.
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*
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* @return the default value, in bytes, of the underlying cipher's key size.
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*/
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public int defaultKeySize()
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{
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return cipher.defaultKeySize();
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}
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/**
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* Returns an {@link Iterator} over the supported block sizes. Each element
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* returned by this object is an {@link Integer}.
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* <p>
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* The default behaviour is to return an iterator with just one value, which
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* is that currently configured for the underlying block cipher. Concrete
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* implementations may override this behaviour to signal their ability to
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* support other values.
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*
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* @return an {@link Iterator} over the supported block sizes.
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*/
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public Iterator blockSizes()
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{
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ArrayList al = new ArrayList();
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al.add(Integer.valueOf(cipherBlockSize));
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return Collections.unmodifiableList(al).iterator();
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}
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/**
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* Returns an {@link Iterator} over the supported underlying block cipher key
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* sizes. Each element returned by this object is an instance of
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* {@link Integer}.
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*
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* @return an {@link Iterator} over the supported key sizes.
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*/
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public Iterator keySizes()
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{
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return cipher.keySizes();
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}
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public void init(Map attributes) throws InvalidKeyException,
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IllegalStateException
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{
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synchronized (lock)
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{
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if (state != -1)
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throw new IllegalStateException();
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Integer want = (Integer) attributes.get(STATE);
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if (want != null)
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{
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switch (want.intValue())
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{
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case ENCRYPTION:
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state = ENCRYPTION;
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break;
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case DECRYPTION:
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state = DECRYPTION;
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break;
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default:
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throw new IllegalArgumentException();
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}
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}
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Integer bs = (Integer) attributes.get(MODE_BLOCK_SIZE);
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modeBlockSize = (bs == null ? cipherBlockSize : bs.intValue());
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byte[] iv = (byte[]) attributes.get(IV);
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if (iv != null)
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this.iv = (byte[]) iv.clone();
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else
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this.iv = new byte[modeBlockSize];
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cipher.init(attributes);
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setup();
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}
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}
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public int currentBlockSize()
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{
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if (state == -1)
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throw new IllegalStateException();
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return modeBlockSize;
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}
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public void reset()
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{
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synchronized (lock)
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{
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state = -1;
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iv = null;
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cipher.reset();
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teardown();
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}
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}
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public boolean selfTest()
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{
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int ks;
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Iterator bit;
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for (Iterator kit = keySizes(); kit.hasNext();)
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{
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ks = ((Integer) kit.next()).intValue();
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for (bit = blockSizes(); bit.hasNext();)
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if (! testSymmetry(ks, ((Integer) bit.next()).intValue()))
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return false;
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}
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return true;
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}
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public abstract Object clone();
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/** The initialisation phase of the concrete mode implementation. */
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public abstract void setup();
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/** The termination phase of the concrete mode implementation. */
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public abstract void teardown();
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public abstract void encryptBlock(byte[] in, int i, byte[] out, int o);
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public abstract void decryptBlock(byte[] in, int i, byte[] out, int o);
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private boolean testSymmetry(int ks, int bs)
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{
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try
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{
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IMode mode = (IMode) this.clone();
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byte[] iv = new byte[cipherBlockSize]; // all zeroes
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byte[] k = new byte[ks];
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int i;
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for (i = 0; i < ks; i++)
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k[i] = (byte) i;
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int blockCount = 5;
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int limit = blockCount * bs;
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byte[] pt = new byte[limit];
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for (i = 0; i < limit; i++)
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pt[i] = (byte) i;
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byte[] ct = new byte[limit];
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byte[] cpt = new byte[limit];
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Map map = new HashMap();
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map.put(KEY_MATERIAL, k);
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map.put(CIPHER_BLOCK_SIZE, Integer.valueOf(cipherBlockSize));
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map.put(STATE, Integer.valueOf(ENCRYPTION));
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map.put(IV, iv);
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map.put(MODE_BLOCK_SIZE, Integer.valueOf(bs));
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mode.reset();
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mode.init(map);
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for (i = 0; i < blockCount; i++)
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mode.update(pt, i * bs, ct, i * bs);
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mode.reset();
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map.put(STATE, Integer.valueOf(DECRYPTION));
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mode.init(map);
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for (i = 0; i < blockCount; i++)
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mode.update(ct, i * bs, cpt, i * bs);
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return Arrays.equals(pt, cpt);
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}
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catch (Exception x)
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{
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x.printStackTrace(System.err);
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return false;
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}
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}
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}
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