package gnu.crypto.mode;
// ----------------------------------------------------------------------------
// $Id: ModeFactory.java,v 1.10 2005/10/06 04:24:17 rsdio Exp $
//
// Copyright (C) 2001, 2002, 2004 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
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// 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 gnu.crypto.cipher.CipherFactory;
import gnu.crypto.cipher.IBlockCipher;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* <p>A <i>Factory</i> to instantiate block cipher modes of operations.</p>
*
* @version $Revision: 1.10 $
*/
public class ModeFactory implements Registry {
// Constants and variables
// -------------------------------------------------------------------------
// Constructor(s)
// -------------------------------------------------------------------------
/** Trivial constructor to enforce Singleton pattern. */
private ModeFactory() {
super();
}
// Class methods
// -------------------------------------------------------------------------
/**
* <p>Returns an instance of a block cipher mode of operations given its name
* and characteristics of the underlying block cipher.</p>
*
* @param mode the case-insensitive name of the mode of operations.
* @param cipher the case-insensitive name of the block cipher.
* @param cipherBlockSize the block size, in bytes, of the underlying cipher.
* @return an instance of the block cipher algorithm, operating in a given
* mode of operations, or <code>null</code> if none found.
* @exception InternalError if either the mode or the underlying block cipher
* implementation does not pass its self-test.
*/
public static IMode
getInstance(String mode, String cipher, int cipherBlockSize) {
if (mode == null || cipher == null) {
return null;
}
mode = mode.trim();
cipher = cipher.trim();
IBlockCipher cipherImpl = CipherFactory.getInstance(cipher);
if (cipherImpl == null) {
return null;
}
return getInstance(mode, cipherImpl, cipherBlockSize);
}
public static IMode
getInstance(String mode, IBlockCipher cipher, int cipherBlockSize) {
// ensure that cipherBlockSize is valid for the chosen underlying cipher
boolean ok = false;
for (Iterator it = cipher.blockSizes(); it.hasNext(); ) {
ok = (cipherBlockSize == ((Integer) it.next()).intValue());
if (ok) {
break;
}
}
if (!ok) {
throw new IllegalArgumentException("cipherBlockSize");
}
IMode result = null;
if (mode.equalsIgnoreCase(ECB_MODE)) {
result = new ECB(cipher, cipherBlockSize);
} else if (mode.equalsIgnoreCase(CTR_MODE)) {
result = new CTR(cipher, cipherBlockSize);
} else if (mode.equalsIgnoreCase(ICM_MODE)) {
result = new ICM(cipher, cipherBlockSize);
} else if (mode.equalsIgnoreCase(OFB_MODE)) {
result = new OFB(cipher, cipherBlockSize);
} else if (mode.equalsIgnoreCase(CBC_MODE)) {
result = new CBC(cipher, cipherBlockSize);
} else if (mode.equalsIgnoreCase(CFB_MODE)) {
result = new CFB(cipher, cipherBlockSize);
} else if (mode.equalsIgnoreCase(EAX_MODE)) {
result = new EAX(cipher, cipherBlockSize);
}
if (result != null && !result.selfTest()) {
throw new InternalError(result.name());
}
return result;
}
/**
* <p>Returns a {@link java.util.Set} of names of mode supported by this
* <i>Factory</i>.</p>
*
* @return a {@link java.util.Set} of mode names (Strings).
*/
public static final Set getNames() {
synchronized (ModeFactory.class) {
if (names == null) {
HashSet hs = new HashSet();
hs.add(ECB_MODE);
hs.add(CTR_MODE);
hs.add(ICM_MODE);
hs.add(OFB_MODE);
hs.add(CBC_MODE);
hs.add(CFB_MODE);
hs.add(EAX_MODE);
names = Collections.unmodifiableSet(hs);
}
}
return names;
}
private static Set names;
// Instance methods
// -------------------------------------------------------------------------
}