/* ECB.java -- 
   Copyright (C) 2001, 2002, 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
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General Public License for more details.

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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
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Linking this library statically or dynamically with other modules is
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permission to link this library with independent modules to produce an
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package gnu.javax.crypto.mode;

import gnu.java.security.Registry;
import gnu.javax.crypto.cipher.IBlockCipher;

/**
 * <p>The implementation of the Electronic Codebook mode.</p>
 *
 * <p>The Electronic Codebook (ECB) mode is a confidentiality mode that is
 * defined as follows:</p>
 *
 * <ul>
 *    <li>ECB Encryption: C<sub>j</sub> = CIPH<sub>K</sub>(P<sub>j</sub>) for j = 1...n</li>
 *    <li>ECB Decryption: P<sub>j</sub> = CIPH<sup>-1</sup><sub>K</sub>(C<sub>j</sub>) for j = 1...n</li>
 * </ul>
 *
 * <p>In ECB encryption, the forward cipher function is applied directly, and
 * independently, to each block of the plaintext. The resulting sequence of
 * output blocks is the ciphertext.</p>
 *
 * <p>In ECB decryption, the inverse cipher function is applied directly, and
 * independently, to each block of the ciphertext. The resulting sequence of
 * output blocks is the plaintext.</p>
 *
 * <p>References:</p>
 *
 * <ol>
 *    <li><a href="http://csrc.nist.gov/encryption/modes/Recommendation/Modes01.pdf">
 *    Recommendation for Block Cipher Modes of Operation Methods and Techniques</a>,
 *    Morris Dworkin.</li>
 * </ol>
 */
public class ECB extends BaseMode implements Cloneable
{

  // Constants and variables
  // -------------------------------------------------------------------------

  // Constructor(s)
  // -------------------------------------------------------------------------

  /**
   * <p>Trivial package-private constructor for use by the Factory class.</p>
   *
   * @param underlyingCipher the underlying cipher implementation.
   * @param cipherBlockSize the underlying cipher block size to use.
   */
  ECB(IBlockCipher underlyingCipher, int cipherBlockSize)
  {
    super(Registry.ECB_MODE, underlyingCipher, cipherBlockSize);
  }

  /**
   * <p>Private constructor for cloning purposes.</p>
   *
   * @param that the mode to clone.
   */
  private ECB(ECB that)
  {
    this((IBlockCipher) that.cipher.clone(), that.cipherBlockSize);
  }

  // Class methods
  // -------------------------------------------------------------------------

  // Instance methods
  // -------------------------------------------------------------------------

  // java.lang.Cloneable interface implementation ----------------------------

  public Object clone()
  {
    return new ECB(this);
  }

  // Implementation of abstract methods in BaseMode --------------------------

  public void setup()
  {
    if (modeBlockSize != cipherBlockSize)
      {
        throw new IllegalArgumentException(IMode.MODE_BLOCK_SIZE);
      }
  }

  public void teardown()
  {
  }

  public void encryptBlock(byte[] in, int i, byte[] out, int o)
  {
    cipher.encryptBlock(in, i, out, o);
  }

  public void decryptBlock(byte[] in, int i, byte[] out, int o)
  {
    cipher.decryptBlock(in, i, out, o);
  }
}