package gnu.crypto.cipher;

// ----------------------------------------------------------------------------
// $Id: IBlockCipher.java,v 1.8 2005/10/06 04:24:14 rsdio Exp $
//
// Copyright (C) 2001, 2002, 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
//
//    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.
// ----------------------------------------------------------------------------

import java.security.InvalidKeyException;
import java.util.Iterator;
import java.util.Map;

/**
 * <p>The basic visible methods of any symmetric key block cipher.</p>
 *
 * <p>A symmetric key block cipher is a function that maps n-bit plaintext
 * blocks to n-bit ciphertext blocks; n being the cipher's <i>block size</i>.
 * This encryption function is parameterised by a k-bit key, and is invertible.
 * Its inverse is the decryption function.</p>
 *
 * <p>Possible initialisation values for an instance of this type are:</p>
 *
 * <ul>
 *    <li>The block size in which to operate this block cipher instance. This
 *    value is <b>optional</b>, if unspecified, the block cipher's default
 *    block size shall be used.</li>
 *
 *    <li>The byte array containing the user supplied key material to use for
 *    generating the cipher's session key(s). This value is <b>mandatory</b>
 *    and should be included in the initialisation parameters. If it isn't,
 *    an {@link IllegalStateException} will be thrown if any method, other than
 *    <code>reset()</code> is invoked on the instance. Furthermore, the size of
 *    this key material shall be taken as an indication on the key size in which
 *    to operate this instance.</li>
 * </ul>
 *
 * <p><b>IMPLEMENTATION NOTE</b>: Although all the concrete classes in this
 * package implement the {@link Cloneable} interface, it is important to note
 * here that such an operation <b>DOES NOT</b> clone any session key material
 * that may have been used in initialising the source cipher (the instance to be
 * cloned). Instead a clone of an already initialised cipher is another instance
 * that operates with the <b>same block size</b> but without any knowledge of
 * neither key material nor key size.</p>
 *
 * @version $Revision: 1.8 $
 */
public interface IBlockCipher extends Cloneable {

   // Constants
   // -------------------------------------------------------------------------

   /**
    * <p>Property name of the block size in which to operate a block cipher.
    * The value associated with this property name is taken to be an
    * {@link Integer}.</p>
    */
   String CIPHER_BLOCK_SIZE = "gnu.crypto.cipher.block.size";

   /**
    * <p>Property name of the user-supplied key material. The value associated
    * to this property name is taken to be a byte array.</p>
    */
   String KEY_MATERIAL = "gnu.crypto.cipher.key.material";

   // Methods
   // -------------------------------------------------------------------------

   /**
    * <p>Returns the canonical name of this instance.</p>
    *
    * @return the canonical name of this instance.
    */
   String name();

   /**
    * <p>Returns the default value, in bytes, of the algorithm's block size.</p>
    *
    * @return the default value, in bytes, of the algorithm's block size.
    */
   int defaultBlockSize();

   /**
    * <p>Returns the default value, in bytes, of the algorithm's key size.</p>
    *
    * @return the default value, in bytes, of the algorithm's key size.
    */
   int defaultKeySize();

   /**
    * <p>Returns an {@link Iterator} over the supported block sizes. Each
    * element returned by this object is an {@link Integer}.</p>
    *
    * @return an {@link Iterator} over the supported block sizes.
    */
   Iterator blockSizes();

   /**
    * <p>Returns an {@link Iterator} over the supported key sizes. Each element
    * returned by this object is an {@link Integer}.</p>
    *
    * @return an {@link Iterator} over the supported key sizes.
    */
   Iterator keySizes();

   /**
    * <p>Returns a clone of this instance.</p>
    *
    * @return a clone copy of this instance.
    */
   Object clone();

   /**
    * <p>Initialises the algorithm with designated attributes. Permissible names
    * and values are described in the class documentation above.</p>
    *
    * @param attributes a set of name-value pairs that describes the desired
    * future behaviour of this instance.
    * @exception InvalidKeyException if the key data is invalid.
    * @exception IllegalStateException if the instance is already initialised.
    * @see #KEY_MATERIAL
    * @see #CIPHER_BLOCK_SIZE
    */
   void init(Map attributes)
   throws InvalidKeyException, IllegalStateException;

   /**
    * <p>Returns the currently set block size for this instance.</p>
    *
    * @return the current block size for this instance.
    * @exception IllegalStateException if the instance is not initialised.
    */
   int currentBlockSize() throws IllegalStateException;

   /**
    * <p>Resets the algorithm instance for re-initialisation and use with other
    * characteristics. This method always succeeds.</p>
    */
   void reset();

   /**
    * <p>Encrypts exactly one block of plaintext.</p>
    *
    * @param in the plaintext.
    * @param inOffset index of <code>in</code> from which to start considering
    * data.
    * @param out the ciphertext.
    * @param outOffset index of <code>out</code> from which to store result.
    * @exception IllegalStateException if the instance is not initialised.
    */
   void encryptBlock(byte[] in, int inOffset, byte[] out, int outOffset)
   throws IllegalStateException;

   /**
    * <p>Decrypts exactly one block of ciphertext.</p>
    *
    * @param in the plaintext.
    * @param inOffset index of <code>in</code> from which to start considering
    * data.
    * @param out the ciphertext.
    * @param outOffset index of <code>out</code> from which to store result.
    * @exception IllegalStateException if the instance is not initialised.
    */
   void decryptBlock(byte[] in, int inOffset, byte[] out, int outOffset)
   throws IllegalStateException;

   /**
    * <p>A <i>correctness</i> test that consists of basic symmetric encryption /
    * decryption test(s) for all supported block and key sizes, as well as one
    * (1) variable key Known Answer Test (KAT).</p>
    *
    * @return <code>true</code> if the implementation passes simple
    * <i>correctness</i> tests. Returns <code>false</code> otherwise.
    */
   boolean selfTest();
}
