joint feldman protocol with test

destributed-key-generation/src/main/java/FeldmanVerifiableSecretSharing/ShamirSecretSharing/Polynomial.java

@@ -208,6 +208,16 @@ public class Polynomial implements Comparable<Polynomial> {
             this.y = new BigInteger(pointMessage.getY().toByteArray());
         }
 
+        /**
+         * constructor
+         * @param x
+         * @param y
+         */
+        public Point(BigInteger x,BigInteger y) {
+            this.x = x;
+            this.y = y;
+        }
+
         public DKGMessages.SecretMessage.Point asMessage(){
             return DKGMessages.SecretMessage.Point.newBuilder()
                     .setX(ByteString.copyFrom(x.toByteArray()))

destributed-key-generation/src/main/java/FeldmanVerifiableSecretSharing/ShamirSecretSharing/SecretSharing.java

@@ -53,7 +53,7 @@ public class SecretSharing {
      *
      * @return polynomial.image(i)%q
      */
-    protected Polynomial.Point getShare(int i){
+    protected final Polynomial.Point getShare(int i){
         assert (i > 0 && i <= n);
         return new Polynomial.Point(BigInteger.valueOf(i), polynomial, q);
     }

destributed-key-generation/src/main/java/JointFeldmanProtocol/DKG.java

@@ -11,6 +11,7 @@ import java.math.BigInteger;
 import java.util.HashSet;
 import java.util.Random;
 import java.util.Set;
+import java.util.concurrent.Callable;
 
 /**
  * Created by Tzlil on 2/5/2016.
@@ -19,28 +20,31 @@ import java.util.Set;
  */
 public class DKG extends VerifiableSecretSharing implements Runnable{
 
-    private Network.User user;
+    private final int id;
-    private Network.MailHandler handler;
+    private final Network.User user; // send and receive messages throw network
-    private Polynomial.Point[] shares;
+
-    private Polynomial.Point[] myshares;
+    private final BigInteger[] ys; // container for y values that
-    private BigInteger[][] commitmentsArray;
+    private final Polynomial.Point[] shares; // shares[i] equivalent to Si,id in terms of the protocol
-    private BigInteger[] ys;
+    private final BigInteger[][] commitmentsArray; // commitmentsArray[i] equivalent to Ai in terms of the protocol
-    final ComplainState[][] complainStates;
+    private final ComplainState[][] complainStates; // complainStates[i][j] == state of Pj's complaint against Pi
-    private Set<Integer> QUAL;
+
+    private final Set<Integer> QUAL; // set of all non-disqualified parties
+    private final BigInteger[] commitments; // public verification values
+    private Polynomial.Point share; // final share of the secrete
+    private BigInteger y; // final public value
 
-    private BigInteger x;
-    private BigInteger y;
-    private BigInteger[] commitments;
 
     public DKG(int t, int n, BigInteger x, Random random, BigInteger p, BigInteger q, BigInteger g,Network network) {
         super(t, n, x, random, p, q, g);
 
         this.commitmentsArray = new BigInteger[n][t + 1];
         this.shares = new Polynomial.Point[n];
-        this.myshares = new Polynomial.Point[n];
+        this.user = network.connect(new Handler());
-        this.handler = new Handler();
+        this.id = user.getID();
-        this.user = network.connect(handler);
         this.complainStates = new ComplainState[n][n];
+        this.QUAL = new HashSet<Integer>();
+        this.ys = new BigInteger[n];
+        this.commitments = new BigInteger[t + 1];
 
         for (int i = 0; i < n; i ++){
             for (int j = 0 ; j < n ; j ++)
@@ -49,44 +53,67 @@ public class DKG extends VerifiableSecretSharing implements Runnable{
 
     }
 
+    /**
+     * use for simulate real distributed protocol
+     */
+    @Override
+    public void run() {
+        user.getReceiverThread().start();
+        stage1();
+        stage2();
+        stage3();
+        stage4();
+        user.getReceiverThread().interrupt();
+    }
 
+    /**
+     * stage1 according to the protocol
+     *  1. Pi broadcasts Aik for k = 0,...,t.
+     *  2. Pi computes the shares Sij for j = 1,...,n and sends Sij secretly to Pj.
+     */
     private void stage1(){
-        int i = user.getID();
+        // for avoiding edge cases, sets commitmentsArray[id - 1]
         BigInteger[] commitments = super.getCommitments();
-        System.arraycopy(commitments, 0, commitmentsArray[i - 1], 0, commitmentsArray[i - 1].length);
+        System.arraycopy(commitments, 0, commitmentsArray[id - 1], 0, commitmentsArray[id - 1].length);
 
+        // broadcasts commitments
         CommitmentMessage commitment;
-        for (int k = 1; k <= commitmentsArray[i - 1].length; k ++){
+        for (int k = 0; k <= t ; k ++){
             commitment = CommitmentMessage.newBuilder()
                             .setK(k)
-                            .setCommitment(ByteString.copyFrom(commitmentsArray[i - 1][k - 1].toByteArray()))
+                            .setCommitment(ByteString.copyFrom(commitmentsArray[id - 1][k].toByteArray()))
                             .build();
             user.broadcast(Mail.Type.COMMITMENT,commitment);
         }
 
+        // computes and sends shares
         SecretMessage secret;
         for (int j = 1; j <= n ; j++ ){
-            if(j != i){
+            if(j != id){
-                myshares[j - 1] = super.getShare(j);
                 secret = SecretMessage.newBuilder()
-                            .setSecret(myshares[j - 1].asMessage())
+                            .setSecret(getShare(j).asMessage())
                             .build();
                 user.send(j, Mail.Type.SECRET,secret);
             }
+            else{
+                shares[id - 1] = super.getShare(id);
+            }
         }
         while (!isStage1Complete()){
             try {
-                Thread.sleep(30);
+                Thread.sleep(300);
             } catch (InterruptedException e) {
                 // do nothing
             }
         }
     }
 
+    /**
+     * @return true iff all shares and commitments were received
+     */
     private boolean isStage1Complete(){
-        int id = user.getID();
+        for (int i = 1 ; i <= n ; i++){
-        for (int j = 1 ; j <= n ; j++){
+            if(shares[i - 1] == null)
-            if(id != j && shares[j - 1] == null)
                 return false;
         }
 
@@ -99,28 +126,36 @@ public class DKG extends VerifiableSecretSharing implements Runnable{
         return true;
     }
 
+    /**
+     * @param secret
+     * @param i
+     * @return g ^ Sij == verify(j,Ai,zpstar) (mod p)
+     */
     private boolean isValidSecret(Polynomial.Point secret, int i){
         int j = secret.x.intValue();
-        return zpstar.multiply(g,secret.y).equals(verify(j,commitmentsArray[i],zpstar));
+        return zpstar.multiply(g,secret.y).equals(verify(j,commitmentsArray[i - 1],zpstar));
     }
 
+    /**
+     * stage2 according to the protocol
+     *  Pj verifies all the shares he received (using isValidSecret)
+     *  if check fails for an index i, Pj broadcasts a complaint against Pi.
+     *  Pj broadcasts yj value at the end of this stage
+     */
     private void stage2(){
-        int j = user.getID();
+        ys[id - 1] = super.getY();
-        QUAL = new HashSet<Integer>();
         ComplaintMessage complaint;
         for (int i = 1; i <= n ; i++ ){
-            if(isValidSecret(shares[i - 1],j)) {
+            if(id != i && !isValidSecret(shares[i - 1],i)) {
-                QUAL.add(i);
-            }else{
                 //message = new Message(Type.Complaint, j)
                 complaint = ComplaintMessage.newBuilder()
                                 .setId(i)
                                 .build();
                 user.broadcast(Mail.Type.COMPLAINT,complaint);
-                complainStates[j - 1][i - 1] = ComplainState.Waiting;
+                complainStates[i - 1][id - 1] = ComplainState.Waiting;
             }
         }
-        //sending y after Complaints
+        //broadcast y after all complaints
         YMessage yMessage = YMessage.newBuilder()
                 .setY(ByteString.copyFrom(super.getY().toByteArray()))
                 .build();
@@ -128,87 +163,99 @@ public class DKG extends VerifiableSecretSharing implements Runnable{
 
         while (!isStage2Complete()){
             try {
-                Thread.sleep(30);
+                Thread.sleep(300);
             } catch (InterruptedException e) {
                 // do nothing
             }
         }
     }
 
+    /**
+     * @return true iff all yi received for i = 1,...,n .
+     */
     private boolean isStage2Complete() {
-        int id = user.getID();
         for (int j = 1; j <= n ; j++) {
-            if (id != j && ys[j - 1] == null)
+            if (j != id && ys[j - 1] == null)
                 return false;
         }
-        for (int i = 0; i < complainStates.length;i++){
-            for (int j =0 ; j < complainStates[i].length;j++){
-                switch (complainStates[i][j]){
-                    case Waiting:
-                        return false;
-                    default:
-                        break;
-                }
-            }
-        }
         return true;
     }
 
+
+    /**
+     * stage3 according to the protocol
+     *  1. if more than t players complain against a player Pi he is disqualified.
+     *  2. Pi broadcasts the share Sij for each complaining player Pj.
+     *  3. if any of the revealed shares fails the verification test, player Pi is disqualified.
+     *  4. set QUAL to be the set of non-disqualified players.
+     */
     private void stage3(){
-        for (int i = 0; i < complainStates.length;i++){
+
-            ComplainState state = ComplainState.Non;
+        // broadcasts Sij for each complaint against Pid
-            for (int j = 0 ; j < complainStates[i].length;j++){
+        for (int j = 1 ; j <= complainStates[id - 1].length;j++) {
-                switch (complainStates[i][j]){
+            switch (complainStates[id - 1][j - 1]) {
-                    case Disqualified:
+                case Waiting:
-                        state = ComplainState.Disqualified;
+                    user.broadcast(Mail.Type.SECRET, SecretMessage.newBuilder()
-                        break;
+                            .setSecret(getShare(j).asMessage())
-                    case NonDisqualified:
+                            .build());
-                        if(state == ComplainState.Non){
+                    complainStates[id - 1][j - 1] = ComplainState.NonDisqualified;
-                            state = ComplainState.NonDisqualified;
-                        }
-                        break;
-                    default:
-                        break;
-                }
-            }
-            switch (state){
-                case Disqualified:
-                    if(QUAL.contains(i + 1)){
-                        QUAL.remove(i + 1);
-                    }
-                    break;
-                case NonDisqualified:
-                    if (!QUAL.contains(i + 1)){
-                        QUAL.add(i + 1);
-                    }
                     break;
                 default:
                     break;
             }
         }
+
+        // wait until there is no complaint waiting for answer
+        for (int i = 0; i < complainStates.length;i++){
+            for (int j = 0 ; j < complainStates[i].length;j++){
+                while (complainStates[i][j].equals(ComplainState.Waiting)){
+                    try {
+                        Thread.sleep(300);
+                    } catch (InterruptedException e) {
+                        // do nothing
+                    }
+                }
+            }
+        }
+
+        // add each non-disqualified player to QUAL
+        boolean nonDisqualified;
+        for (int i = 1; i <= complainStates.length;i++){
+            nonDisqualified = true;
+            for (int j = 1 ; j <= complainStates[i - 1].length;j++){
+                nonDisqualified &= complainStates[i - 1][j - 1].equals(ComplainState.Disqualified);
+            }
+            if(nonDisqualified){
+                QUAL.add(i);
+            }
+        }
     }
 
+    /**
+     * stage4 according to the protocol
+     *  1. public value y is computed as y = multiplication of yi mod p for i in QUAL
+     *  2. public verification values are computed as Ak = multiplication of Aik mod p for i in QUAL for k = 0,...,t
+     *  3. Pj sets is share of the secret as xj = sum of Sij mod q for i in QUAL
+     */
     private void stage4(){
-        BigInteger y = zpstar.zero();
+        this.y = zpstar.zero();
         for (int i : QUAL) {
-            y = zpstar.add(y , ys[i - 1]);
+            this.y = zpstar.add(this.y , ys[i - 1]);
         }
-        this.commitments = new BigInteger[t];
         BigInteger commitment;
-        for (int k = 1; k <= t ; k++){
+        for (int k = 0; k <= t ; k++){
             commitment = zpstar.zero();
             for (int i : QUAL) {
-                commitment = zpstar.add(commitment,commitmentsArray[i - 1][k - 1]);
+                commitment = zpstar.add(commitment,commitmentsArray[i - 1][k]);
             }
-            commitments[k - 1] = commitment;
+            commitments[k] = commitment;
         }
 
-        int j = user.getID();
+        BigInteger xj = BigInteger.ZERO;
-        BigInteger x = BigInteger.ZERO;
         for (int i : QUAL) {
-            x = x.add(shares[i - 1].y);
+            xj = xj.add(shares[i - 1].y);
         }
-        this.x = x.mod(q);
+        this.share = new Polynomial.Point(BigInteger.valueOf(id) , xj.mod(q));
     }
 
     @Override
@@ -221,18 +268,8 @@ public class DKG extends VerifiableSecretSharing implements Runnable{
         return Arrays.clone(commitments);
     }
 
-    @Override
-    protected Polynomial.Point getShare(int i) {
-        return null;
-    }
 
-    @Override
+
-    public void run() {
-        stage1();
-        stage2();
-        stage3();
-        stage4();
-    }
 
     private enum ComplainState{
         Non, Waiting,Disqualified,NonDisqualified
@@ -240,11 +277,7 @@ public class DKG extends VerifiableSecretSharing implements Runnable{
 
     private class Handler implements Network.MailHandler {
 
-        final int id;
+        private Handler() {}
-
-        private Handler() {
-            this.id = user.getID();
-        }
 
         void handelSecretMessage(Mail mail) throws InvalidProtocolBufferException {
             if(shares[mail.getSender() - 1] == null) {
@@ -255,12 +288,12 @@ public class DKG extends VerifiableSecretSharing implements Runnable{
                 }else{
                     int i = mail.getSender();
                     int j = secret.x.intValue();
-                    switch (complainStates[i][j]){
+                    switch (complainStates[i - 1][j - 1]){
                         case Waiting:
                             if(isValidSecret(secret,i)){
-                                complainStates[i][j] = ComplainState.NonDisqualified;
+                                complainStates[i - 1][j - 1] = ComplainState.NonDisqualified;
                             }else{
-                                complainStates[i][j] = ComplainState.Disqualified;
+                                complainStates[i - 1][j - 1] = ComplainState.Disqualified;
                             }
                             break;
                         default:
@@ -291,22 +324,17 @@ public class DKG extends VerifiableSecretSharing implements Runnable{
         }
 
         void handelComplaintMessage(Mail mail) throws InvalidProtocolBufferException {
+            int id = user.getID();
             if(!mail.getIsPrivate()) { //broadcast only
                 ComplaintMessage complaintMessage = ComplaintMessage.parseFrom(mail.getMessage());
                 int i = complaintMessage.getId();
                 int j = mail.getSender();
-                if(i == id){
+                switch (complainStates[i - 1][j - 1]){
-                    user.broadcast(Mail.Type.SECRET,SecretMessage.newBuilder()
+                    case Non:
-                            .setSecret(myshares[j].asMessage())
+                        complainStates[i - 1][j - 1] = ComplainState.Waiting;
-                            .build());
+                        break;
-                }else{
+                    default:
-                    switch (complainStates[i - 1][j - 1]){
+                        break;
-                        case Non:
-                            complainStates[i - 1][j - 1] = ComplainState.Waiting;
-                            break;
-                        default:
-                            break;
-                    }
                 }
             }
         }

destributed-key-generation/src/main/java/JointFeldmanProtocol/Network.java

@@ -7,6 +7,9 @@ import java.util.Queue;
 import java.util.concurrent.ArrayBlockingQueue;
 /**
  * Created by Tzlil on 2/7/2016.
+ * JointFeldamn protocol assumes all parties can communicate throw broadcast chanel
+ * and private chanel (for each pair)
+ * this class simulates it
  */
 public class Network {
 
@@ -28,7 +31,8 @@ public class Network {
         Integer id = availableIDs.poll();
         if (id == null)
             return null;
-        return new User(id,messageHandler);
+        users[id - 1] = new User(id,messageHandler);
+        return users[id - 1];
     }
 
     private boolean sendMessage(User sender,int destination,Mail.Type type,Message message){
@@ -70,13 +74,12 @@ public class Network {
         private final MailHandler messageHandler;
         private final Queue<Mail> mailbox;
         private final int ID;
-
+        private final Thread receiverThread;
         public User(int ID, MailHandler messageHandler) {
-            this.mailbox = new ArrayBlockingQueue<Mail>(n*n);
+            this.mailbox = new ArrayBlockingQueue<Mail>(1 << n);
             this.ID = ID;
             this.messageHandler = messageHandler;
-            Thread thread = new Thread(new Receiver());
+            this.receiverThread = new Thread(new Receiver());
-            thread.run();
         }
 
         public boolean send(int id, Mail.Type type,Message message){
@@ -88,7 +91,9 @@ public class Network {
         public int getID() {
             return ID;
         }
-
+        public Thread getReceiverThread(){
+            return receiverThread;
+        }
         private class Receiver implements Runnable{
             @Override
             public void run() {

destributed-key-generation/src/test/java/FeldmanVerifiableSecretSharing/ShamirSecretSharing/PolynomialTests/InterpolationTest.java

@@ -33,7 +33,6 @@ public class InterpolationTest {
     public Polynomial.Point[] randomPoints(Polynomial p){
         Polynomial.Point[] points = new Polynomial.Point[p.getDegree() + 1];
         BigInteger x;
-        Boolean b;
         Set<BigInteger> set = new HashSet();
         for (int i = 0; i < points.length; i++){
             x = new BigInteger(bits,random);

destributed-key-generation/src/test/java/JointFeldmanProtocol/DKGTest.java

@@ -0,0 +1,57 @@
+package JointFeldmanProtocol;
+
+import org.factcenter.qilin.primitives.concrete.Zpstar;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.math.BigInteger;
+import java.util.Random;
+
+/**
+ * Created by Tzlil on 2/9/2016.
+ */
+public class DKGTest {
+
+
+    DKG[] dkgs;
+    Thread[] threads;
+    int tests = 1 << 10;
+    Random random;
+
+    @Before
+    public void settings(){
+        BigInteger p = BigInteger.valueOf(2903);
+        BigInteger q = p.subtract(BigInteger.ONE).divide(BigInteger.valueOf(2));
+        Zpstar zpstar = new Zpstar(p);
+        random = new Random();
+        BigInteger g;
+        BigInteger ZERO = zpstar.zero();
+        do{
+            g = zpstar.sample(random);
+        }while (!g.equals(ZERO) && !zpstar.multiply(g,q).equals(ZERO));// sample from QRZp*
+        int t = 8;
+        int n = 20
+                ;
+        Network network = new Network(n);
+        dkgs = new DKG[n];
+        threads = new Thread[n];
+        for (int i = 0 ; i < n ; i++) {
+            dkgs[i] = new DKG(t, n, new BigInteger(q.bitLength(), random).mod(q), random, p, q, g, network);
+            threads[i] = new Thread(dkgs[i]);
+        }
+    }
+
+    @Test
+    public void DKGTest() throws Exception {
+        for (int i = 0 ; i < threads.length ; i++){
+            threads[i].start();
+        }
+        for (int i = 0 ; i < threads.length ; i++){
+            threads[i].join();
+        }
+
+        for (int i = 0; i < dkgs.length - 1 ; i++){
+            assert (dkgs[i].getY().equals(dkgs[i+1].getY()));
+        }
+    }
+}