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/* BaseKeyWrappingAlgorithm.java -- FIXME: briefly describe file purpose

   Copyright (C) 2006 Free Software Foundation, Inc.

This file is 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, or (at your option)

any later version.

GNU Classpath 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 GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 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

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package gnu.javax.crypto.kwa;

import gnu.java.security.util.PRNG;

import java.security.InvalidKeyException;

import java.util.Collections;

import java.util.Map;

import javax.crypto.ShortBufferException;

/**

 * A base class to facilitate implementation of concrete Key Wrapping

 * Algorithms.

 */

public abstract class BaseKeyWrappingAlgorithm

     implements IKeyWrappingAlgorithm

{

  /** The canonical name of the key wrapping algorithm. */

  protected String name;

  /** A source of randomness if/when needed by concrete implementations. */

  private PRNG prng;

  /**

   * Protected constructor.

   *

   * @param name the key wrapping algorithm canonical name.

   */

  protected BaseKeyWrappingAlgorithm(String name)

  {

    super();

  }

  public String name()

  {

    return this.name;

  }

  public void init(Map attributes) throws InvalidKeyException

  {

    if (attributes == null)

      attributes = Collections.EMPTY_MAP;

    engineInit(attributes);

  }

  public int wrap(byte[] in, int inOffset, int length, byte[] out, int outOffset)

      throws ShortBufferException

  {

    if (outOffset < 0)

      throw new IllegalArgumentException("Output offset MUST NOT be negative");

    byte[] result = wrap(in, inOffset, length);

    if (outOffset + result.length > out.length)

      throw new ShortBufferException();

    System.arraycopy(result, 0, out, outOffset, result.length);

    return result.length;

  }

  public byte[] wrap(byte[] in, int inOffset, int length)

  {

    if (inOffset < 0)

      throw new IllegalArgumentException("Input offset MUST NOT be negative");

    if (length < 0)

      throw new IllegalArgumentException("Input length MUST NOT be negative");

    return engineWrap(in, inOffset, length);

  }

  public int unwrap(byte[] in, int inOffset, int length,

                    byte[] out, int outOffset)

      throws ShortBufferException, KeyUnwrappingException

  {

    if (outOffset < 0)

      throw new IllegalArgumentException("Output offset MUST NOT be negative");

    byte[] result = engineUnwrap(in, inOffset, length);

    if (outOffset + result.length > out.length)

      throw new ShortBufferException();

    System.arraycopy(result, 0, out, outOffset, result.length);

    return result.length;

  }

  public byte[] unwrap(byte[] in, int inOffset, int length)

      throws KeyUnwrappingException

  {

    if (inOffset < 0)

      throw new IllegalArgumentException("Input offset MUST NOT be negative");

    if (length < 0)

      throw new IllegalArgumentException("Input length MUST NOT be negative");

    return engineUnwrap(in, inOffset, length);

  }

  protected abstract void engineInit(Map attributes) throws InvalidKeyException;

  protected abstract byte[] engineWrap(byte[] in, int inOffset, int length);

  protected abstract byte[] engineUnwrap(byte[] in, int inOffset, int length)

      throws KeyUnwrappingException;

  /** @return a strong pseudo-random number generator if/when needed. */

  protected PRNG getDefaultPRNG()

  {

    if (prng == null)

      prng = PRNG.getInstance();

    return prng;

  }

}