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 public class SRP6TLSServer extends SRP6KeyAgreement
  66 {
  67
  68   // Constants and variables
  69   // -------------------------------------------------------------------------
  70
  71   /** The user's ephemeral key pair. */
  72   private KeyPair hostKeyPair;
  73
  74   /** The SRP password database. */
  75   private SRPAuthInfoProvider passwordDB;
  76
  77   // Constructor(s)
  78   // -------------------------------------------------------------------------
  79
  80   // default 0-arguments constructor
  81
  82   // Class methods
  83   // -------------------------------------------------------------------------
  84
  85   // Instance methods
  86   // -------------------------------------------------------------------------
  87
  88   // implementation of abstract methods in base class ------------------------
  89
  90   protected void engineInit(final Map attributes) throws KeyAgreementException
  91   {
  92     rnd = (SecureRandom) attributes.get(SOURCE_OF_RANDOMNESS);
  93
  94     final String md = (String) attributes.get(HASH_FUNCTION);
  95     if (md == null || "".equals(md.trim()))
  96       {
  97         throw new KeyAgreementException("missing hash function");
  98       }
  99     srp = SRP.instance(md);
 100
 101     passwordDB = (SRPAuthInfoProvider) attributes.get(HOST_PASSWORD_DB);
 102     if (passwordDB == null)
 103       {
 104         throw new KeyAgreementException("missing SRP password database");
 105       }
 106   }
 107
 108   protected OutgoingMessage engineProcessMessage(final IncomingMessage in)
 109       throws KeyAgreementException
 110   {
 111     switch (step)
 112       {
 113       case 0:
 114         return sendParameters(in);
 115       case 1:
 116         return computeSharedSecret(in);
 117       default:
 118         throw new IllegalStateException("unexpected state");
 119       }
 120   }
 121
 122   protected void engineReset()
 123   {
 124     hostKeyPair = null;
 125     super.engineReset();
 126   }
 127
 128   // own methods -------------------------------------------------------------
 129
 130   private OutgoingMessage sendParameters(final IncomingMessage in)
 131       throws KeyAgreementException
 132   {
 133     final String I = in.readString();
 134
 135     // get s and v for user identified by I
 136     // ----------------------------------------------------------------------
 137     final Map credentials;
 138     try
 139       {
 140         final Map userID = new HashMap();
 141         userID.put(Registry.SASL_USERNAME, I);
 142         userID.put(SRPRegistry.MD_NAME_FIELD, srp.getAlgorithm());
 143         credentials = passwordDB.lookup(userID);
 144       }
 145     catch (IOException x)
 146       {
 147         throw new KeyAgreementException("computeSharedSecret()", x);
 148       }
 149
 150     final BigInteger s = new BigInteger(
 151                                         1,
 152                                         Util.fromBase64((String) credentials.get(SRPRegistry.SALT_FIELD)));
 153     final BigInteger v = new BigInteger(
 154                                         1,
 155                                         Util.fromBase64((String) credentials.get(SRPRegistry.USER_VERIFIER_FIELD)));
 156
 157     final Map configuration;
 158     try
 159       {
 160         final String mode = (String) credentials.get(SRPRegistry.CONFIG_NDX_FIELD);
 161         configuration = passwordDB.getConfiguration(mode);
 162       }
 163     catch (IOException x)
 164       {
 165         throw new KeyAgreementException("computeSharedSecret()", x);
 166       }
 167
 168     N = new BigInteger(
 169                        1,
 170                        Util.fromBase64((String) configuration.get(SRPRegistry.SHARED_MODULUS)));
 171     g = new BigInteger(
 172                        1,
 173                        Util.fromBase64((String) configuration.get(SRPRegistry.FIELD_GENERATOR)));
 174     // ----------------------------------------------------------------------
 175
 176     // generate an ephemeral keypair
 177     final SRPKeyPairGenerator kpg = new SRPKeyPairGenerator();
 178     final Map attributes = new HashMap();
 179     if (rnd != null)
 180       {
 181         attributes.put(SRPKeyPairGenerator.SOURCE_OF_RANDOMNESS, rnd);
 182       }
 183     attributes.put(SRPKeyPairGenerator.SHARED_MODULUS, N);
 184     attributes.put(SRPKeyPairGenerator.GENERATOR, g);
 185     attributes.put(SRPKeyPairGenerator.USER_VERIFIER, v);
 186     kpg.setup(attributes);
 187     hostKeyPair = kpg.generate();
 188
 189     final BigInteger B = ((SRPPublicKey) hostKeyPair.getPublic()).getY();
 190
 191     final OutgoingMessage result = new OutgoingMessage();
 192     result.writeMPI(N);
 193     result.writeMPI(g);
 194     result.writeMPI(s);
 195     result.writeMPI(B);
 196
 197     return result;
 198   }
 199
 200   protected OutgoingMessage computeSharedSecret(final IncomingMessage in)
 201       throws KeyAgreementException
 202   {
 203     final BigInteger A = in.readMPI();
 204
 205     final BigInteger B = ((SRPPublicKey) hostKeyPair.getPublic()).getY();
 206     final BigInteger u = uValue(A, B); // u = H(A | B)
 207
 208     // compute S = (Av^u) ^ b
 209     final BigInteger b = ((SRPPrivateKey) hostKeyPair.getPrivate()).getX();
 210     final BigInteger v = ((SRPPrivateKey) hostKeyPair.getPrivate()).getV();
 211     final BigInteger S = A.multiply(v.modPow(u, N)).modPow(b, N);
 212
 213     K = S;
 214
 215     complete = true;
 216     return null;
 217   }
 218 }