1 /* BaseKeyAgreementParty.java -- 2 Copyright (C) 2003, 2006 Free Software Foundation, Inc. 3 4 This file is a part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2 of the License, or (at 9 your option) any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; if not, write to the Free Software 18 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 19 USA 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package gnu.javax.crypto.key; 40 41 import gnu.java.security.prng.IRandom; 42 import gnu.java.security.prng.LimitReachedException; 43 import gnu.java.security.util.PRNG; 44 45 import java.math.BigInteger; 46 import java.security.SecureRandom; 47 import java.util.Map; 48 49 /** 50 * A base abstract class to facilitate implementations of concrete key agreement 51 * protocol handlers. 52 */ 53 public abstract class BaseKeyAgreementParty 54 implements IKeyAgreementParty 55 { 56 protected static final BigInteger TWO = BigInteger.valueOf(2L); 57 /** The canonical name of the protocol. */ 58 protected String name; 59 /** Whether the instance is initialised or not. */ 60 protected boolean initialised = false; 61 /** The current step index of the protocol exchange. */ 62 protected int step = -1; 63 /** Whether the exchange has concluded or not. */ 64 protected boolean complete = false; 65 /** The optional {@link SecureRandom} instance to use. */ 66 protected SecureRandom rnd = null; 67 /** The optional {@link IRandom} instance to use. */ 68 protected IRandom irnd = null; 69 /** Our default source of randomness. */ 70 private PRNG prng = null; 71 BaseKeyAgreementParty(String name)72 protected BaseKeyAgreementParty(String name) 73 { 74 super(); 75 76 this.name = name; 77 } 78 name()79 public String name() 80 { 81 return name; 82 } 83 init(Map attributes)84 public void init(Map attributes) throws KeyAgreementException 85 { 86 if (initialised) 87 throw new IllegalStateException("already initialised"); 88 this.engineInit(attributes); 89 initialised = true; 90 this.step = -1; 91 this.complete = false; 92 } 93 processMessage(IncomingMessage in)94 public OutgoingMessage processMessage(IncomingMessage in) 95 throws KeyAgreementException 96 { 97 if (! initialised) 98 throw new IllegalStateException("not initialised"); 99 if (complete) 100 throw new IllegalStateException("exchange has already concluded"); 101 step++; 102 return this.engineProcessMessage(in); 103 } 104 isComplete()105 public boolean isComplete() 106 { 107 return complete; 108 } 109 getSharedSecret()110 public byte[] getSharedSecret() throws KeyAgreementException 111 { 112 if (! initialised) 113 throw new KeyAgreementException("not yet initialised"); 114 if (! isComplete()) 115 throw new KeyAgreementException("not yet computed"); 116 return engineSharedSecret(); 117 } 118 reset()119 public void reset() 120 { 121 if (initialised) 122 { 123 this.engineReset(); 124 initialised = false; 125 } 126 } 127 engineInit(Map attributes)128 protected abstract void engineInit(Map attributes) 129 throws KeyAgreementException; 130 engineProcessMessage(IncomingMessage in)131 protected abstract OutgoingMessage engineProcessMessage(IncomingMessage in) 132 throws KeyAgreementException; 133 engineSharedSecret()134 protected abstract byte[] engineSharedSecret() throws KeyAgreementException; 135 engineReset()136 protected abstract void engineReset(); 137 138 /** 139 * Fills the designated byte array with random data. 140 * 141 * @param buffer the byte array to fill with random data. 142 */ nextRandomBytes(byte[] buffer)143 protected void nextRandomBytes(byte[] buffer) 144 { 145 if (rnd != null) 146 rnd.nextBytes(buffer); 147 else if (irnd != null) 148 try 149 { 150 irnd.nextBytes(buffer, 0, buffer.length); 151 } 152 catch (LimitReachedException lre) 153 { 154 irnd = null; 155 getDefaultPRNG().nextBytes(buffer); 156 } 157 else 158 getDefaultPRNG().nextBytes(buffer); 159 } 160 getDefaultPRNG()161 private PRNG getDefaultPRNG() 162 { 163 if (prng == null) 164 prng = PRNG.getInstance(); 165 166 return prng; 167 } 168 } 169