From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001
From: upstream source tree <ports@midipix.org>
Date: Sun, 15 Mar 2015 20:14:05 -0400
Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified
 gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream
 tarball.

downloading a git-generated archive based on the 'upstream' tag
should provide you with a source tree that is binary identical
to the one extracted from the above tarball.

if you have obtained the source via the command 'git clone',
however, do note that line-endings of files in your working
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files in the upstream repository.
---
 .../gnu/javax/crypto/key/dh/ElGamalSender.java     | 112 +++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 libjava/classpath/gnu/javax/crypto/key/dh/ElGamalSender.java

(limited to 'libjava/classpath/gnu/javax/crypto/key/dh/ElGamalSender.java')

diff --git a/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalSender.java b/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalSender.java
new file mode 100644
index 000000000..bc9643500
--- /dev/null
+++ b/libjava/classpath/gnu/javax/crypto/key/dh/ElGamalSender.java
@@ -0,0 +1,112 @@
+/* ElGamalSender.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.dh;
+
+import gnu.javax.crypto.key.KeyAgreementException;
+import gnu.javax.crypto.key.IncomingMessage;
+import gnu.javax.crypto.key.OutgoingMessage;
+
+import java.math.BigInteger;
+import java.security.SecureRandom;
+import java.util.Map;
+
+import javax.crypto.interfaces.DHPublicKey;
+
+/**
+ * This implementation is the sender's part of the ElGamal key agreement
+ * exchange (A in [HAC]).
+ *
+ * @see ElGamalKeyAgreement
+ */
+public class ElGamalSender
+    extends ElGamalKeyAgreement
+{
+  /** The recipient's public key. */
+  private DHPublicKey B;
+
+  // default 0-arguments constructor
+
+  protected void engineInit(Map attributes) throws KeyAgreementException
+  {
+    rnd = (SecureRandom) attributes.get(SOURCE_OF_RANDOMNESS);
+    // One-time setup (key generation and publication). Each user B generates
+    // a keypair and publishes its public key
+    B = (DHPublicKey) attributes.get(KA_ELGAMAL_RECIPIENT_PUBLIC_KEY);
+    if (B == null)
+      throw new KeyAgreementException("missing recipient public key");
+  }
+
+  protected OutgoingMessage engineProcessMessage(IncomingMessage in)
+      throws KeyAgreementException
+  {
+    switch (step)
+      {
+      case 0:
+        return computeSharedSecret(in);
+      default:
+        throw new IllegalStateException("unexpected state");
+      }
+  }
+
+  private OutgoingMessage computeSharedSecret(IncomingMessage in)
+      throws KeyAgreementException
+  {
+    BigInteger p = B.getParams().getP();
+    BigInteger g = B.getParams().getG();
+    BigInteger yb = B.getY();
+    // A chooses a random integer x, 1 <= x <= p-2
+    // rfc-2631 restricts x to only be in [2, p-1]
+    BigInteger p_minus_2 = p.subtract(TWO);
+    byte[] xBytes = new byte[(p_minus_2.bitLength() + 7) / 8];
+    BigInteger x;
+    do
+      {
+        nextRandomBytes(xBytes);
+        x = new BigInteger(1, xBytes);
+      }
+    while (x.compareTo(TWO) >= 0 && x.compareTo(p_minus_2) <= 0);
+    // A sends B the message: g^x mod p
+    OutgoingMessage result = new OutgoingMessage();
+    result.writeMPI(g.modPow(x, p));
+    // A computes the key as K = (yb)^x mod p
+    ZZ = yb.modPow(x, p); // ZZ = (yb ^ xa) mod p
+    complete = true;
+    return result;
+  }
+}
-- 
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