- fix election crypto

- multi-way elections
- high-level signature containers
- fix bug in mesh test case
- fix bug in Strings.java
- ivy repo

1 files changed, 64 insertions, 0 deletions

diff --git a/src/main/java/org/gnunet/voting/DisjunctionZkp.java b/src/main/java/org/gnunet/voting/DisjunctionZkp.java
new file mode 100644
index 0000000..cfa823c
--- /dev/null
+++ b/src/main/java/org/gnunet/voting/DisjunctionZkp.java
@@ -0,0 +1,64 @@
+/*
+ This file is part of GNUnet.
+ (C) 2014 Christian Grothoff (and other contributing authors)
+
+ GNUnet 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 3, or (at your
+ option) any later version.
+
+ GNUnet 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 GNUnet; see the file COPYING.  If not, write to the
+ Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA.
+ */
+
+package org.gnunet.voting;
+
+import org.gnunet.construct.*;
+import org.gnunet.secretsharing.Parameters;
+
+import java.math.BigInteger;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+/**
+ * Disjunction of Chaum Pedersen ZKPs.
+ */
+public class DisjunctionZkp implements Message {
+    @UInt64
+    public int numProofs;
+    @FixedSizeIntegerArray(signed = true, bitSize = 8, length = Parameters.elgamalBits / 8)
+    public byte[] challenge_c;
+    @VariableSizeArray(lengthField = "numProofs")
+    public ChaumPedersenZkp[] chaumPedersenZkps;
+
+    public boolean verifyChallenge() {
+        BigInteger c_actual = new BigInteger(1, challenge_c);
+        BigInteger c_expected = BigInteger.ZERO;
+        for (ChaumPedersenZkp chaumPedersenZkp : chaumPedersenZkps) {
+            BigInteger d = new BigInteger(1, chaumPedersenZkp.challenge_d);
+            c_expected = c_expected.add(d).mod(Parameters.elgamalQ);
+        }
+        return c_actual.equals(c_expected) && computeChallengeFromCommits().equals(c_actual);
+    }
+
+    public BigInteger computeChallengeFromCommits() {
+        MessageDigest digest;
+        try {
+            digest = MessageDigest.getInstance("SHA-512");
+        } catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException("crypto algorithm 'SHA-512' required but not provided");
+        }
+        for (ChaumPedersenZkp chaumPedersenZkp : chaumPedersenZkps) {
+            digest.update(chaumPedersenZkp.commit_a);
+            digest.update(chaumPedersenZkp.commit_b);
+        }
+        return (new BigInteger(digest.digest())).mod(Parameters.elgamalQ);
+    }
+}