ModeStage.java

/* ModeStage.java -- 
   Copyright (C) 2003, 2006 Free Software Foundation, Inc.

This file is a part of GNU Classpath.

GNU Classpath 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 of the License, or (at
your option) any later version.

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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.

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Foundation, Inc., 51 Franklin St, 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
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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package gnu.javax.crypto.assembly;

import gnu.javax.crypto.mode.IMode;

import java.security.InvalidKeyException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

/**
 * An {@link IMode} {@link Stage} in a {@link Cascade} Cipher chain.
 * <p>
 * Such a stage wraps an implementation of a Block Cipher Mode of Operation
 * ({@link IMode}) to allow inclusion of such an instance in a cascade of block
 * ciphers.
 */
class ModeStage
    extends Stage
{
  private IMode delegate;

  private transient Set cachedBlockSizes;

  ModeStage(IMode mode, Direction forwardDirection)
  {
    super(forwardDirection);

    delegate = mode;
    cachedBlockSizes = null;
  }

  public Set blockSizes()
  {
    if (cachedBlockSizes == null)
      {
        HashSet result = new HashSet();
        for (Iterator it = delegate.blockSizes(); it.hasNext();)
          result.add(it.next());
        cachedBlockSizes = Collections.unmodifiableSet(result);
      }
    return cachedBlockSizes;
  }

  void initDelegate(Map attributes) throws InvalidKeyException
  {
    Direction flow = (Direction) attributes.get(DIRECTION);
    attributes.put(IMode.STATE,
                   Integer.valueOf(flow.equals(forward) ? IMode.ENCRYPTION
                                                        : IMode.DECRYPTION));
    delegate.init(attributes);
  }

  public int currentBlockSize() throws IllegalStateException
  {
    return delegate.currentBlockSize();
  }

  void resetDelegate()
  {
    delegate.reset();
  }

  void updateDelegate(byte[] in, int inOffset, byte[] out, int outOffset)
  {
    delegate.update(in, inOffset, out, outOffset);
  }

  public boolean selfTest()
  {
    return delegate.selfTest();
  }
}