package gnu.crypto.cipher;

// ----------------------------------------------------------------------------
// $Id: CipherFactory.java,v 1.11 2003/06/14 14:43:18 raif Exp $
//
// Copyright (C) 2001, 2002, 2003 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.,
//    59 Temple Place - Suite 330,
//    Boston, MA 02111-1307
//    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 gnu.crypto.Registry;

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * <p>A <i>Factory</i> to instantiate symmetric block cipher instances.</p>
 *
 * @version $Revision: 1.11 $
 */
public class CipherFactory implements Registry {

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

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

    /**
     * Trivial constructor to enforce Singleton pattern.
     */
    private CipherFactory() {
        super();
    }

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

    /**
     * <p>Returns an instance of a block cipher given its name.</p>
     *
     * @param name the case-insensitive name of the symmetric-key block cipher
     *             algorithm.
     * @return an instance of the designated cipher algorithm, or
     *         <code>null</code> if none is found.
     * @throws InternalError if the implementation does not pass its
     *                       self-test.
     */
    public static final IBlockCipher getInstance(String name) {
        if (name == null) {
            return null;
        }

        name = name.trim();
        IBlockCipher result = null;
        if (name.equalsIgnoreCase(ANUBIS_CIPHER)) {
            result = new Anubis();
        } else if (name.equalsIgnoreCase(BLOWFISH_CIPHER)) {
            result = new Blowfish();
        } else if (name.equalsIgnoreCase(DES_CIPHER)) {
            result = new DES();
        } else if (name.equalsIgnoreCase(KHAZAD_CIPHER)) {
            result = new Khazad();
        } else if (name.equalsIgnoreCase(RIJNDAEL_CIPHER)
                || name.equalsIgnoreCase(AES_CIPHER)) {
            result = new Rijndael();
        } else if (name.equalsIgnoreCase(SERPENT_CIPHER)) {
            result = new Serpent();
        } else if (name.equalsIgnoreCase(SQUARE_CIPHER)) {
            result = new Square();
        } else if (name.equalsIgnoreCase(TRIPLEDES_CIPHER)
                || name.equalsIgnoreCase(DESEDE_CIPHER)) {
            result = new TripleDES();
        } else if (name.equalsIgnoreCase(TWOFISH_CIPHER)) {
            result = new Twofish();
        } else if (name.equalsIgnoreCase(CAST5_CIPHER)
                || (name.equalsIgnoreCase(CAST128_CIPHER)
                || (name.equalsIgnoreCase(CAST_128_CIPHER)))) {
            result = new Cast5();
        } else if (name.equalsIgnoreCase(NULL_CIPHER)) {
            result = new NullCipher();
        }

        if (result != null && !result.selfTest()) {
            throw new InternalError(result.name());
        }

        return result;
    }

    /**
     * <p>Returns a {@link Set} of symmetric key block cipher implementation
     * names supported by this <i>Factory</i>.</p>
     *
     * @return a {@link Set} of block cipher names (Strings).
     */
    public static final Set getNames() {
        HashSet hs = new HashSet();
        hs.add(ANUBIS_CIPHER);
        hs.add(BLOWFISH_CIPHER);
        hs.add(DES_CIPHER);
        hs.add(KHAZAD_CIPHER);
        hs.add(RIJNDAEL_CIPHER);
        hs.add(SERPENT_CIPHER);
        hs.add(SQUARE_CIPHER);
        hs.add(TRIPLEDES_CIPHER);
        hs.add(TWOFISH_CIPHER);
        hs.add(CAST5_CIPHER);
        hs.add(NULL_CIPHER);

        return Collections.unmodifiableSet(hs);
    }

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