libjava/classpath/gnu/javax/crypto/key/srp6/SRP6TLSServer.java

   1 /* SRP6TLSServer.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.srp6;
  40
  41 import gnu.java.security.Registry;
  42 import gnu.java.security.util.Util;
  43 import gnu.javax.crypto.key.KeyAgreementException;
  44 import gnu.javax.crypto.key.OutgoingMessage;
  45 import gnu.javax.crypto.key.IncomingMessage;
  46 import gnu.javax.crypto.sasl.srp.SRP;
  47 import gnu.javax.crypto.sasl.srp.SRPAuthInfoProvider;
  48 import gnu.javax.crypto.sasl.srp.SRPRegistry;
  49
  50 import java.io.IOException;
  51 import java.math.BigInteger;
  52 import java.security.KeyPair;
  53 import java.security.SecureRandom;
  54 import java.util.HashMap;
  55 import java.util.Map;
  56
  57 /**
  58  * <p>A variation of the SRP6 key agreement protocol, for the server-side as
  59  * proposed in
  60  * <a href="http://www.ietf.org/internet-drafts/draft-ietf-tls-srp-05.txt">Using
  61  * SRP for TLS Authentication</a>. The only difference between it and the SASL
  62  * variant is that the shared secret is the entity <code>S</code> and not
  63  * <code>H(S)</code>.</p>
  64  *
  65  * @version $Revision: 1.1 $
  66  */
  67 public class SRP6TLSServer extends SRP6KeyAgreement
  68 {
  69
  70   // Constants and variables
  71   // -------------------------------------------------------------------------
  72
  73   /** The user's ephemeral key pair. */
  74   private KeyPair hostKeyPair;
  75
  76   /** The SRP password database. */
  77   private SRPAuthInfoProvider passwordDB;
  78
  79   // Constructor(s)
  80   // -------------------------------------------------------------------------
  81
  82   // default 0-arguments constructor
  83
  84   // Class methods
  85   // -------------------------------------------------------------------------
  86
  87   // Instance methods
  88   // -------------------------------------------------------------------------
  89
  90   // implementation of abstract methods in base class ------------------------
  91
  92   protected void engineInit(final Map attributes) throws KeyAgreementException
  93   {
  94     rnd = (SecureRandom) attributes.get(SOURCE_OF_RANDOMNESS);
  95
  96     final String md = (String) attributes.get(HASH_FUNCTION);
  97     if (md == null || "".equals(md.trim()))
  98       {
  99         throw new KeyAgreementException("missing hash function");
 100       }
 101     srp = SRP.instance(md);
 102
 103     passwordDB = (SRPAuthInfoProvider) attributes.get(HOST_PASSWORD_DB);
 104     if (passwordDB == null)
 105       {
 106         throw new KeyAgreementException("missing SRP password database");
 107       }
 108   }
 109
 110   protected OutgoingMessage engineProcessMessage(final IncomingMessage in)
 111       throws KeyAgreementException
 112   {
 113     switch (step)
 114       {
 115       case 0:
 116         return sendParameters(in);
 117       case 1:
 118         return computeSharedSecret(in);
 119       default:
 120         throw new IllegalStateException("unexpected state");
 121       }
 122   }
 123
 124   protected void engineReset()
 125   {
 126     hostKeyPair = null;
 127     super.engineReset();
 128   }
 129
 130   // own methods -------------------------------------------------------------
 131
 132   private OutgoingMessage sendParameters(final IncomingMessage in)
 133       throws KeyAgreementException
 134   {
 135     final String I = in.readString();
 136
 137     // get s and v for user identified by I
 138     // ----------------------------------------------------------------------
 139     final Map credentials;
 140     try
 141       {
 142         final Map userID = new HashMap();
 143         userID.put(Registry.SASL_USERNAME, I);
 144         userID.put(SRPRegistry.MD_NAME_FIELD, srp.getAlgorithm());
 145         credentials = passwordDB.lookup(userID);
 146       }
 147     catch (IOException x)
 148       {
 149         throw new KeyAgreementException("computeSharedSecret()", x);
 150       }
 151
 152     final BigInteger s = new BigInteger(
 153                                         1,
 154                                         Util.fromBase64((String) credentials.get(SRPRegistry.SALT_FIELD)));
 155     final BigInteger v = new BigInteger(
 156                                         1,
 157                                         Util.fromBase64((String) credentials.get(SRPRegistry.USER_VERIFIER_FIELD)));
 158
 159     final Map configuration;
 160     try
 161       {
 162         final String mode = (String) credentials.get(SRPRegistry.CONFIG_NDX_FIELD);
 163         configuration = passwordDB.getConfiguration(mode);
 164       }
 165     catch (IOException x)
 166       {
 167         throw new KeyAgreementException("computeSharedSecret()", x);
 168       }
 169
 170     N = new BigInteger(
 171                        1,
 172                        Util.fromBase64((String) configuration.get(SRPRegistry.SHARED_MODULUS)));
 173     g = new BigInteger(
 174                        1,
 175                        Util.fromBase64((String) configuration.get(SRPRegistry.FIELD_GENERATOR)));
 176     // ----------------------------------------------------------------------
 177
 178     // generate an ephemeral keypair
 179     final SRPKeyPairGenerator kpg = new SRPKeyPairGenerator();
 180     final Map attributes = new HashMap();
 181     if (rnd != null)
 182       {
 183         attributes.put(SRPKeyPairGenerator.SOURCE_OF_RANDOMNESS, rnd);
 184       }
 185     attributes.put(SRPKeyPairGenerator.SHARED_MODULUS, N);
 186     attributes.put(SRPKeyPairGenerator.GENERATOR, g);
 187     attributes.put(SRPKeyPairGenerator.USER_VERIFIER, v);
 188     kpg.setup(attributes);
 189     hostKeyPair = kpg.generate();
 190
 191     final BigInteger B = ((SRPPublicKey) hostKeyPair.getPublic()).getY();
 192
 193     final OutgoingMessage result = new OutgoingMessage();
 194     result.writeMPI(N);
 195     result.writeMPI(g);
 196     result.writeMPI(s);
 197     result.writeMPI(B);
 198
 199     return result;
 200   }
 201
 202   protected OutgoingMessage computeSharedSecret(final IncomingMessage in)
 203       throws KeyAgreementException
 204   {
 205     final BigInteger A = in.readMPI();
 206
 207     final BigInteger B = ((SRPPublicKey) hostKeyPair.getPublic()).getY();
 208     final BigInteger u = uValue(A, B); // u = H(A | B)
 209
 210     // compute S = (Av^u) ^ b
 211     final BigInteger b = ((SRPPrivateKey) hostKeyPair.getPrivate()).getX();
 212     final BigInteger v = ((SRPPrivateKey) hostKeyPair.getPrivate()).getV();
 213     final BigInteger S = A.multiply(v.modPow(u, N)).modPow(b, N);
 214
 215     K = S;
 216
 217     complete = true;
 218     return null;
 219   }
 220 }