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diff --git a/libjava/classpath/gnu/javax/crypto/key/srp6/SRP6User.java b/libjava/classpath/gnu/javax/crypto/key/srp6/SRP6User.java
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+/* SRP6User.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.srp6;
+
+import gnu.java.security.hash.IMessageDigest;
+import gnu.java.security.util.Util;
+import gnu.javax.crypto.key.KeyAgreementException;
+import gnu.javax.crypto.key.IncomingMessage;
+import gnu.javax.crypto.key.OutgoingMessage;
+import gnu.javax.crypto.sasl.srp.SRP;
+
+import java.math.BigInteger;
+import java.security.KeyPair;
+import java.security.SecureRandom;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * The implementation of the User in the SRP-6 protocol.
+ * <p>
+ * Reference:
+ * <ol>
+ * <li><a href="http://srp.stanford.edu/design.html">SRP Protocol Design</a><br>
+ * Thomas J. Wu.</li>
+ * </ol>
+ */
+public class SRP6User
+    extends SRP6KeyAgreement
+{
+  /** The user's identity. */
+  private String I;
+  /** The user's cleartext password. */
+  private byte[] p;
+  /** The user's ephemeral key pair. */
+  private KeyPair userKeyPair;
+
+  // default 0-arguments constructor
+
+  protected void engineInit(final Map attributes) throws KeyAgreementException
+  {
+    rnd = (SecureRandom) attributes.get(SOURCE_OF_RANDOMNESS);
+    N = (BigInteger) attributes.get(SHARED_MODULUS);
+    if (N == null)
+      throw new KeyAgreementException("missing shared modulus");
+    g = (BigInteger) attributes.get(GENERATOR);
+    if (g == null)
+      throw new KeyAgreementException("missing generator");
+    final String md = (String) attributes.get(HASH_FUNCTION);
+    if (md == null || md.trim().length() == 0)
+      throw new KeyAgreementException("missing hash function");
+    srp = SRP.instance(md);
+    I = (String) attributes.get(USER_IDENTITY);
+    if (I == null)
+      throw new KeyAgreementException("missing user identity");
+    p = (byte[]) attributes.get(USER_PASSWORD);
+    if (p == null)
+      throw new KeyAgreementException("missing user password");
+  }
+
+  protected OutgoingMessage engineProcessMessage(final IncomingMessage in)
+      throws KeyAgreementException
+  {
+    switch (step)
+      {
+      case 0:
+        return sendIdentity(in);
+      case 1:
+        return computeSharedSecret(in);
+      default:
+        throw new IllegalStateException("unexpected state");
+      }
+  }
+
+  protected void engineReset()
+  {
+    I = null;
+    p = null;
+    userKeyPair = null;
+    super.engineReset();
+  }
+
+  private OutgoingMessage sendIdentity(final IncomingMessage in)
+      throws KeyAgreementException
+  {
+    // generate an ephemeral keypair
+    final SRPKeyPairGenerator kpg = new SRPKeyPairGenerator();
+    final Map attributes = new HashMap();
+    if (rnd != null)
+      attributes.put(SRPKeyPairGenerator.SOURCE_OF_RANDOMNESS, rnd);
+    attributes.put(SRPKeyPairGenerator.SHARED_MODULUS, N);
+    attributes.put(SRPKeyPairGenerator.GENERATOR, g);
+    kpg.setup(attributes);
+    userKeyPair = kpg.generate();
+    final OutgoingMessage result = new OutgoingMessage();
+    result.writeString(I);
+    result.writeMPI(((SRPPublicKey) userKeyPair.getPublic()).getY());
+    return result;
+  }
+
+  private OutgoingMessage computeSharedSecret(final IncomingMessage in)
+      throws KeyAgreementException
+  {
+    final BigInteger s = in.readMPI();
+    final BigInteger B = in.readMPI();
+    final BigInteger A = ((SRPPublicKey) userKeyPair.getPublic()).getY();
+    final BigInteger u = uValue(A, B); // u = H(A | B)
+    final BigInteger x;
+    try
+      {
+        x = new BigInteger(1, srp.computeX(Util.trim(s), I, p));
+      }
+    catch (Exception e)
+      {
+        throw new KeyAgreementException("computeSharedSecret()", e);
+      }
+    // compute S = (B - 3g^x) ^ (a + ux)
+    final BigInteger a = ((SRPPrivateKey) userKeyPair.getPrivate()).getX();
+    final BigInteger S = B.subtract(THREE.multiply(g.modPow(x, N)))
+                          .modPow(a.add(u.multiply(x)), N);
+    final byte[] sBytes = Util.trim(S);
+    final IMessageDigest hash = srp.newDigest();
+    hash.update(sBytes, 0, sBytes.length);
+    K = new BigInteger(1, hash.digest());
+    complete = true;
+    return null;
+  }
+}