| /* BaseKeyAgreementParty.java -- |
| Copyright (C) 2003, 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 |
| the Free Software Foundation; either version 2 of the License, or (at |
| your option) any later version. |
| |
| GNU Classpath 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 GNU Classpath; if not, write to the Free Software |
| Foundation, Inc., 51 Franklin St, 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. */ |
| |
| |
| package gnu.javax.crypto.key; |
| |
| import gnu.java.security.prng.IRandom; |
| import gnu.java.security.prng.LimitReachedException; |
| import gnu.java.security.util.PRNG; |
| |
| import java.math.BigInteger; |
| import java.security.SecureRandom; |
| import java.util.Map; |
| |
| /** |
| * A base abstract class to facilitate implementations of concrete key agreement |
| * protocol handlers. |
| */ |
| public abstract class BaseKeyAgreementParty |
| implements IKeyAgreementParty |
| { |
| protected static final BigInteger TWO = BigInteger.valueOf(2L); |
| /** The canonical name of the protocol. */ |
| protected String name; |
| /** Whether the instance is initialised or not. */ |
| protected boolean initialised = false; |
| /** The current step index of the protocol exchange. */ |
| protected int step = -1; |
| /** Whether the exchange has concluded or not. */ |
| protected boolean complete = false; |
| /** The optional {@link SecureRandom} instance to use. */ |
| protected SecureRandom rnd = null; |
| /** The optional {@link IRandom} instance to use. */ |
| protected IRandom irnd = null; |
| /** Our default source of randomness. */ |
| private PRNG prng = null; |
| |
| protected BaseKeyAgreementParty(String name) |
| { |
| super(); |
| |
| this.name = name; |
| } |
| |
| public String name() |
| { |
| return name; |
| } |
| |
| public void init(Map attributes) throws KeyAgreementException |
| { |
| if (initialised) |
| throw new IllegalStateException("already initialised"); |
| this.engineInit(attributes); |
| initialised = true; |
| this.step = -1; |
| this.complete = false; |
| } |
| |
| public OutgoingMessage processMessage(IncomingMessage in) |
| throws KeyAgreementException |
| { |
| if (! initialised) |
| throw new IllegalStateException("not initialised"); |
| if (complete) |
| throw new IllegalStateException("exchange has already concluded"); |
| step++; |
| return this.engineProcessMessage(in); |
| } |
| |
| public boolean isComplete() |
| { |
| return complete; |
| } |
| |
| public byte[] getSharedSecret() throws KeyAgreementException |
| { |
| if (! initialised) |
| throw new KeyAgreementException("not yet initialised"); |
| if (! isComplete()) |
| throw new KeyAgreementException("not yet computed"); |
| return engineSharedSecret(); |
| } |
| |
| public void reset() |
| { |
| if (initialised) |
| { |
| this.engineReset(); |
| initialised = false; |
| } |
| } |
| |
| protected abstract void engineInit(Map attributes) |
| throws KeyAgreementException; |
| |
| protected abstract OutgoingMessage engineProcessMessage(IncomingMessage in) |
| throws KeyAgreementException; |
| |
| protected abstract byte[] engineSharedSecret() throws KeyAgreementException; |
| |
| protected abstract void engineReset(); |
| |
| /** |
| * Fills the designated byte array with random data. |
| * |
| * @param buffer the byte array to fill with random data. |
| */ |
| protected void nextRandomBytes(byte[] buffer) |
| { |
| if (rnd != null) |
| rnd.nextBytes(buffer); |
| else if (irnd != null) |
| try |
| { |
| irnd.nextBytes(buffer, 0, buffer.length); |
| } |
| catch (LimitReachedException lre) |
| { |
| irnd = null; |
| getDefaultPRNG().nextBytes(buffer); |
| } |
| else |
| getDefaultPRNG().nextBytes(buffer); |
| } |
| |
| private PRNG getDefaultPRNG() |
| { |
| if (prng == null) |
| prng = PRNG.getInstance(); |
| |
| return prng; |
| } |
| } |