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package gnu.crypto.mac;
// ----------------------------------------------------------------------------
// $Id: HMacFactory.java,v 1.4 2003/04/10 10:41:01 raif 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.,
// 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 gnu.crypto.hash.HashFactory;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* A Factory to instantiate Keyed-Hash Message Authentication Code
* (HMAC) algorithm instances.
*
* @version $Revision: 1.4 $
*/
public class HMacFactory implements Registry {
// Constants and variables
// -------------------------------------------------------------------------
// Constructor(s)
// -------------------------------------------------------------------------
/** Trivial constructor to enforce Singleton pattern. */
private HMacFactory() {
super();
}
// Class methods
// -------------------------------------------------------------------------
/**
* Return an instance of a HMAC algorithm given the name of its
* underlying hash function, prefixed with the literal defined in
* {@link Registry#HMAC_NAME_PREFIX}.
*
* @param name the fully qualified name of the underlying algorithm: composed
* as the concatenation of a literal prefix (see {@link Registry#HMAC_NAME_PREFIX})
* and the name of the underlying hash algorithm.
* @return an instance of the HMAC algorithm, or null if
* none can be constructed.
* @exception InternalError if the implementation does not pass its self-test.
*/
public static IMac getInstance(String name) {
if (name == null) {
return null;
}
name = name.trim();
name = name.toLowerCase();
if (!name.startsWith(HMAC_NAME_PREFIX)) {
return null;
}
// strip the prefix
name = name.substring(HMAC_NAME_PREFIX.length()).trim();
IMac result = new HMac(HashFactory.getInstance(name));
if (result != null && !result.selfTest()) {
throw new InternalError(result.name());
}
return result;
}
/**
* Returns a {@link java.util.Set} of names of HMAC algorithms
* supported by this Factory.
*
* @return a {@link java.util.Set} of HMAC algorithm names (Strings).
*/
public static final Set getNames() {
Set hashNames = HashFactory.getNames();
HashSet hs = new HashSet();
for (Iterator it = hashNames.iterator(); it.hasNext(); ) {
hs.add(HMAC_NAME_PREFIX+((String) it.next()));
}
return Collections.unmodifiableSet(hs);
}
// Instance methods
// -------------------------------------------------------------------------
}