Fixed the Selector classes.

Fixed the crypto classes to handle signatures as well.
Some more other fixes

meerkat-common/src/main/proto/meerkat/voting.proto

@@ -71,6 +71,12 @@ message EncryptedBallot {
     RerandomizableEncryptedMessage data = 2;
 }
 
+message SignedEncryptedBallot {
+    EncryptedBallot encrypted_ballot = 1;
+    bytes signer_id = 2;
+    Signature signature = 3;
+}
+
 message BallotSecrets {
     PlaintextBallot plaintext_ballot = 1;
 
@@ -126,3 +132,16 @@ message ElectionParams {
     // Data required in order to access the Bulletin Board Servers
     BulletinBoardClientParams bulletinBoardClientParams = 8;
 }
+
+message Category {
+    repeated uint32 questionIndex = 1;
+}
+
+message CategoryChooser {
+    repeated Category category = 1;
+}
+
+message SimpleCategoriesSelectionData {
+    Category shared_defaults = 1;
+    repeated CategoryChooser categoryChooser = 2;
+}

voting-booth/src/main/java/meerkat/voting/controller/VotingBoothController.java

@@ -2,12 +2,11 @@ package meerkat.voting.controller;
 
 import meerkat.protobuf.Voting.*;
 import meerkat.voting.controller.selector.QuestionSelector;
+import meerkat.voting.encryptor.VBCryptoManager;
 import meerkat.voting.ui.VotingBoothUI;
-import meerkat.voting.encryptor.VotingBoothEncryptor;
 import meerkat.voting.output.BallotOutputDevice;
 import meerkat.voting.storage.StorageManager;
 
-import java.util.ArrayList;
 import java.util.List;
 
 
@@ -19,12 +18,12 @@ public interface VotingBoothController extends Runnable{
     /**
      * initialize by setting all the different components of the Voting Booth to be recognized by this controller
      * @param outputDevice the ballot output device. Naturally a printer and/or ethernet connection
-     * @param vbEncryptor the encryption module
+     * @param vbCrypto the crypto module
      * @param vbUI User interface in which the voter chooses his answers
      * @param vbStorageManager storage component for handling files and USB sticks
      */
     public void init (BallotOutputDevice outputDevice,
-                      VotingBoothEncryptor vbEncryptor,
+                      VBCryptoManager vbCrypto,
                       VotingBoothUI vbUI,
                       StorageManager vbStorageManager);
 

voting-booth/src/main/java/meerkat/voting/controller/VotingBoothImpl.java

@@ -1,17 +1,19 @@
 package meerkat.voting.controller;
 
-import com.google.protobuf.ByteString;
 import meerkat.protobuf.Voting.*;
 import meerkat.voting.controller.callbacks.*;
 import meerkat.voting.controller.commands.*;
 import meerkat.voting.controller.selector.QuestionSelector;
-import meerkat.voting.encryptor.VotingBoothEncryptor;
+import meerkat.voting.encryptor.VBCryptoManager;
+import meerkat.voting.encryptor.VBCryptoManager.EncryptionAndSecrets;
 import meerkat.voting.output.BallotOutputDevice;
 import meerkat.voting.storage.StorageManager;
 import meerkat.voting.ui.VotingBoothUI;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.io.IOException;
+import java.security.SignatureException;
 import java.util.List;
 import java.util.concurrent.LinkedBlockingQueue;
 
@@ -21,7 +23,7 @@ import java.util.concurrent.LinkedBlockingQueue;
 public class VotingBoothImpl implements VotingBoothController {
 
     private BallotOutputDevice outputDevice;
-    private VotingBoothEncryptor encryptor;
+    private VBCryptoManager crypto;
     private VotingBoothUI ui;
     private StorageManager storageManager;
     private List<BallotQuestion> questionsForChoosingChannel;
@@ -49,12 +51,12 @@ public class VotingBoothImpl implements VotingBoothController {
 
     @Override
     public void init(BallotOutputDevice outputDevice,
-                     VotingBoothEncryptor vbEncryptor,
+                     VBCryptoManager vbCrypto,
                      VotingBoothUI vbUI,
                      StorageManager vbStorageManager) {
         logger.info("init is called");
         this.outputDevice = outputDevice;
-        this.encryptor = vbEncryptor;
+        this.crypto = vbCrypto;
         this.ui = vbUI;
         this.storageManager = vbStorageManager;
     }
@@ -105,7 +107,7 @@ public class VotingBoothImpl implements VotingBoothController {
         logger.info("callShutDown command has been called");
         shutDownHasBeenCalled = true;
         queue.clear();
-        queue.add(new ShutDownCommand());
+        ui.callShutDown();
     }
 
     private void handleSingleTask (ControllerCommand task) {
@@ -138,14 +140,6 @@ public class VotingBoothImpl implements VotingBoothController {
         else if (task instanceof ReportErrorCommand) {
             doReportErrorAndForceRestart((ReportErrorCommand)task);
         }
-        else if (task instanceof ShutDownCommand) {
-            // wasShutDownCalled is now true. Do nothing.
-            // The program will not access the command queue anymore, and will exit normally
-            if (!wasShutDownCalled()) {
-                logger.warn("Received a ShutDownCommand command. At this point shutDownHasBeenCalled flag should have been True, but it's not...");
-                shutDownHasBeenCalled = true;
-            }
-        }
         else {
             logger.error("handleSingleTask: unknown type of ControllerCommand received: " + task.getClass().getName());
             doReportErrorAndForceRestart(SystemMessages.getSomethingWrongMessage());
@@ -208,7 +202,7 @@ public class VotingBoothImpl implements VotingBoothController {
             state.stateIdentifier = VBState.ANSWER_QUESTIONS;
             List<BallotAnswer> channelChoiceAnswers = task.channelChoiceAnswers;
             state.channelIdentifier = questionSelector.getChannelIdentifier(channelChoiceAnswers);
-            state.channelSpecificQuestions = questionSelector.selectQuestionsForVoter(channelChoiceAnswers);
+            state.channelSpecificQuestions = questionSelector.selectQuestionsForVoter(state.channelIdentifier);
             ui.askVoterQuestions(state.channelSpecificQuestions,
                     new VotingCallback(generateRequestIdentifier(), state.currentBallotSerialNumber, this.queue));
         }
@@ -229,7 +223,7 @@ public class VotingBoothImpl implements VotingBoothController {
                             state.currentBallotSerialNumber,
                             this.queue));
             outputDevice.commitToBallot(state.plaintextBallot,
-                    state.encryptedBallot,
+                    state.signedEncryptedBallot,
                     new OutputDeviceCallback(generateRequestIdentifier(), state.currentBallotSerialNumber, this.queue));
         }
         else {
@@ -243,8 +237,14 @@ public class VotingBoothImpl implements VotingBoothController {
                 .setSerialNumber(task.getBallotSerialNumber())
                 .addAllAnswers(task.getVotingAnswers())
                 .build();
-        VotingBoothEncryptor.EncryptionAndSecrets encryptionAndSecrets = encryptor.encrypt(state.plaintextBallot);
+        EncryptionAndSecrets encryptionAndSecrets = null;
-        state.encryptedBallot = encryptionAndSecrets.getEncryptedBallot();
+        try {
+             encryptionAndSecrets = crypto.encrypt(state.plaintextBallot);
+        }
+        catch (SignatureException | IOException e) {
+            // TODO: handle exception
+        }
+        state.signedEncryptedBallot = encryptionAndSecrets.getSignedEncryptedBallot();
         state.secrets = encryptionAndSecrets.getSecrets();
     }
 
@@ -287,20 +287,20 @@ public class VotingBoothImpl implements VotingBoothController {
 
     private class ControllerState {
         public VBState stateIdentifier;
-        public int channelIdentifier;
+        public byte[] channelIdentifier;
         public List<BallotQuestion> channelSpecificQuestions;
         public PlaintextBallot plaintextBallot;
-        public EncryptedBallot encryptedBallot;
+        public SignedEncryptedBallot signedEncryptedBallot;
         public BallotSecrets secrets;
         public int lastRequestIdentifier;
         public long currentBallotSerialNumber;
 
         public ControllerState () {
             plaintextBallot = null;
-            encryptedBallot = null;
+            signedEncryptedBallot = null;
             secrets = null;
             lastRequestIdentifier = -1;
-            channelIdentifier = -1;
+            channelIdentifier = null;
             channelSpecificQuestions = null;
             currentBallotSerialNumber = 0;
         }
@@ -311,7 +311,7 @@ public class VotingBoothImpl implements VotingBoothController {
         }
 
         public void clearCiphertext () {
-            encryptedBallot = null;
+            signedEncryptedBallot = null;
             secrets = null;
         }
     }

voting-booth/src/main/java/meerkat/voting/controller/callbacks/ChannelChoiceCallback.java

@@ -23,21 +23,21 @@ public class ChannelChoiceCallback extends ControllerCallback<List<BallotAnswer>
 
     @Override
     public void onSuccess(List<BallotAnswer> result) {
-        if (result.size() != 0) {
         logger.debug("callback for channel choice returned success");
         enqueueCommand(new ChannelDeterminedCommand(getRequestIdentifier(), getBallotSerialNumber(), result));
     }
-        else {
-            logger.debug("ChannelChoiceCallback got a cancellation response: " + result);
-            enqueueCommand(new RestartVotingCommand(getRequestIdentifier(), getBallotSerialNumber()));
-        }
-    }
 
     @Override
     public void onFailure(Throwable t) {
+        if (t instanceof VoterCancelException) {
+            logger.debug("ChannelChoiceCallback got a cancellation response");
+            enqueueCommand(new RestartVotingCommand(getRequestIdentifier(), getBallotSerialNumber()));
+        }
+        else {
             logger.error("channel choice initiated a failure: " + t);
             enqueueCommand(new ReportErrorCommand(getRequestIdentifier(),
                     getBallotSerialNumber(),
                     SystemMessages.getUnsuccessfulChannelChoiceMessage()));
         }
     }
+}

voting-booth/src/main/java/meerkat/voting/controller/callbacks/VoterCancelException.java

@@ -0,0 +1,8 @@
+package meerkat.voting.controller.callbacks;
+
+/**
+ * Created by hai on 06/06/16.
+ */
+public class VoterCancelException extends Exception{
+    //
+}

voting-booth/src/main/java/meerkat/voting/controller/callbacks/VotingCallback.java

@@ -23,21 +23,21 @@ public class VotingCallback extends ControllerCallback<List<BallotAnswer>> {
 
     @Override
     public void onSuccess(List<BallotAnswer> result) {
-        if (result.size() != 0) {
         logger.debug("callback for voting returned success");
         enqueueCommand(new EncryptAndCommitBallotCommand(getRequestIdentifier(), getBallotSerialNumber(), result));
     }
-        else {
-            logger.debug("VotingCallback got a cancellation response: " + result);
-            enqueueCommand(new RestartVotingCommand(getRequestIdentifier(), getBallotSerialNumber()));
-        }
-    }
 
     @Override
     public void onFailure(Throwable t) {
+        if (t instanceof VoterCancelException) {
+            logger.debug("VotingCallback got a cancellation response");
+            enqueueCommand(new RestartVotingCommand(getRequestIdentifier(), getBallotSerialNumber()));
+        }
+        else {
             logger.error("voting initiated a failure: " + t);
             enqueueCommand(new ReportErrorCommand(getRequestIdentifier(),
                     getBallotSerialNumber(),
                     SystemMessages.getUnsuccessfulVotingMessage()));
         }
     }
+}

voting-booth/src/main/java/meerkat/voting/controller/commands/ShutDownCommand.java

@@ -1,10 +0,0 @@
-package meerkat.voting.controller.commands;
-
-/**
- * Created by hai on 11/04/16.
- */
-public class ShutDownCommand extends ControllerCommand {
-    public ShutDownCommand() {
-        super(0, 0);
-    }
-}

voting-booth/src/main/java/meerkat/voting/controller/selector/QuestionSelector.java

@@ -8,11 +8,8 @@ import java.util.List;
  */
 public interface QuestionSelector {
 
-    public void setAllBallotQuestions (List<BallotQuestion> allBallotQuestions);
+    public byte[] getChannelIdentifier (List<BallotAnswer> channelChoiceAnswers);
 
-    public void setSelectionData(SelectionData data);
+    public List<BallotQuestion> selectQuestionsForVoter (byte[] channelIdentifier);
 
-    public int getChannelIdentifier (List<BallotAnswer> channelChoiceAnswers);
-
-    public List<BallotQuestion> selectQuestionsForVoter (List<BallotAnswer> channelChoiceAnswers);
 }

voting-booth/src/main/java/meerkat/voting/controller/selector/SelectionData.java

@@ -1,7 +0,0 @@
-package meerkat.voting.controller.selector;
-
-/**
- * Created by hai on 11/05/16.
- */
-public class SelectionData {
-}

voting-booth/src/main/java/meerkat/voting/controller/selector/SimpleCategoriesData.java

@@ -1,97 +0,0 @@
-package meerkat.voting.controller.selector;
-
-/**
- * This class is the SelectionData used to initialize a SimpleListCategoriesSelector.
- * It holds a table of question categories.
- * Every answer in the channel choice phase dictates a category of questions to include in the ballot.
- * This class is simply only the data class of these categories.
- * Specifically the questionSelectionsByAnswer member is this categories table:
- * questionSelectionsByAnswer[questionNumber][answerNumber] is an array of question indices to include in ballot
- * whenever the voter answered answerNumber on question questionNumber in the channel choice phase.
- * Also the sharedDefaults member is a category of question indices to include for EVERY voter,
- * regardless of his channel choice answers
- */
-public class SimpleCategoriesData extends SelectionData{
-
-    private int[] sharedDefaults;  // a category of questions to include for every voter
-    // the categories
-    // first index is the question number, the second is the answer number. the value is an array of question indices in this category
-    private int[][][] questionSelectionsByAnswer;
-    private int maxQuestionNumber;
-
-    public SimpleCategoriesData() {
-        sharedDefaults = new int[0];
-        questionSelectionsByAnswer = new int[0][][];
-        maxQuestionNumber = -1;
-    }
-
-    public void setSharedDefaults(int[] sharedDefaultsIndices) {
-        this.sharedDefaults = sharedDefaultsIndices.clone();
-        maxQuestionNumber = Math.max(maxQuestionNumber, maxIntInArray(sharedDefaultsIndices));
-    }
-
-    public int[] getSharedDefaults() {
-        return sharedDefaults;
-    }
-
-    public void setItem(int questionNumber, int answerNumber, int[] questionIndices) {
-        if (questionNumber >= questionSelectionsByAnswer.length) {
-            int[][][] tmp = new int[questionNumber+1][][];
-            System.arraycopy(questionSelectionsByAnswer, 0, tmp, 0, questionSelectionsByAnswer.length);
-            tmp[questionNumber] = new int[0][];
-            questionSelectionsByAnswer = tmp;
-        }
-
-        if (answerNumber >= questionSelectionsByAnswer[questionNumber].length) {
-            int[][] tmp = new int[answerNumber+1][];
-            System.arraycopy(questionSelectionsByAnswer[questionNumber], 0,
-                    tmp, 0, questionSelectionsByAnswer[questionNumber].length);
-            questionSelectionsByAnswer[questionNumber] = tmp;
-        }
-
-        questionSelectionsByAnswer[questionNumber][answerNumber] = questionIndices.clone();
-        maxQuestionNumber = Math.max(maxQuestionNumber, maxIntInArray(questionIndices));
-    }
-
-    public int[] getItem(int questionNumber, int answerNumber) {
-        return questionSelectionsByAnswer[questionNumber][answerNumber];
-    }
-
-    public int getMaxQuestionNumber() {
-        return maxQuestionNumber;
-    }
-
-
-    private static int maxIntInArray(int[] arr) {
-        int m = -1;
-        for (int i: arr) {
-            m = Math.max(i , m);
-        }
-        return m;
-    }
-
-    public String toString () {
-        String s = "SimpleCategoriesData:\n";
-        s += "shared : " + arrayToString(sharedDefaults) + "\n";
-        s += "map : \n";
-        for (int questionNumber = 0; questionNumber < questionSelectionsByAnswer.length; ++questionNumber) {
-            for (int answerNumber = 0; answerNumber < questionSelectionsByAnswer[questionNumber].length; ++answerNumber) {
-                s += "(" + questionNumber + ", " + answerNumber + ") -> " +
-                        arrayToString(questionSelectionsByAnswer[questionNumber][answerNumber]) + "\n";
-            }
-        }
-        return s;
-    }
-
-    private String arrayToString (int[] a) {
-        if (a.length == 0) {
-            return "[]";
-        }
-        String s = "[" + a[0];
-        for (int i = 1; i < a.length; ++i) {
-            s += ", " + a[i];
-        }
-        return s + "]";
-    }
-
-}

voting-booth/src/main/java/meerkat/voting/controller/selector/SimpleListCategoriesSelector.java

@@ -1,89 +1,89 @@
 package meerkat.voting.controller.selector;
 
-import meerkat.protobuf.Voting.BallotAnswer;
+import meerkat.protobuf.Voting.*;
-import meerkat.protobuf.Voting.BallotQuestion;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.lang.Math;
 
 /**
  * A simple implementation of a QuestionSelector.
  * This implementation simply regards every single answer in the channel choice phase as an identifier of a category
  * Every category is an array of ballot questions.
- * Data of categories is initialized and stored by a SimpleCategoriesData object.
+ * Data of categories is initialized and stored by a SimpleCategoriesSelectionData protobuf.
  * After receiving the answers from a channel choice phase, this class simply gathers all the categories
  * chosen and compiles the list of ballot questions to include in the ballot for this voter (a question
  * is included if its index appears in any chosen category, or in the default category shared by all voters)
  */
 public class SimpleListCategoriesSelector implements QuestionSelector {
     protected final static Logger logger = LoggerFactory.getLogger(SimpleListCategoriesSelector.class);
-    private BallotQuestion[] allBallotQuestions;
+
-    private SimpleCategoriesData selectionData;
+    private final BallotQuestion[] allBallotQuestions;
-    private boolean[] isSelected;
+    private final int[] sharedDefaults;
+    private final int[][][] categoryChoosers;
+
+    private final static byte QUESTION_SELECTED = (byte)1;
+    private final static byte QUESTION_NOT_SELECTED = (byte)0;
 
 
-    public SimpleListCategoriesSelector() {
+
-        this.allBallotQuestions = null;
+    public SimpleListCategoriesSelector(List<BallotQuestion> allBallotQuestions, SimpleCategoriesSelectionData data) {
-        this.selectionData = null;
+        this.allBallotQuestions = new BallotQuestion[allBallotQuestions.size()];
+        allBallotQuestions.toArray(this.allBallotQuestions);
+        sharedDefaults = listToIntArray(data.getSharedDefaults().getQuestionIndexList());
+        int[][][] selectionDataTmp = new int[data.getCategoryChooserList().size()][][];
+        int channelChoiceQuestionNumber = 0;
+        for (CategoryChooser catChooser: data.getCategoryChooserList()) {
+            selectionDataTmp[channelChoiceQuestionNumber] = new int[catChooser.getCategoryList().size()][];
+            int channelChoiceAnswerNumber = 0;
+            for (Category category: catChooser.getCategoryList()) {
+                selectionDataTmp[channelChoiceQuestionNumber][channelChoiceAnswerNumber] = listToIntArray(category.getQuestionIndexList());
+                ++channelChoiceAnswerNumber;
             }
-
+            ++channelChoiceQuestionNumber;
-    @Override
-    public void setAllBallotQuestions(List<BallotQuestion> allBallotQuestions) {
-        this.allBallotQuestions = (BallotQuestion[])allBallotQuestions.toArray();
-        isSelected = new boolean[this.allBallotQuestions.length];
-        assertDataValid();
         }
-
+        categoryChoosers = selectionDataTmp;
-    @Override
-    public void setSelectionData(SelectionData data) {
-        if (! (data instanceof SimpleCategoriesData)) {
-            String errorMessage = "Initialization of SimpleListCategoriesSelector with wrong object type";
-            logger.error(errorMessage);
-            throw new RuntimeException(errorMessage);
-        }
-        this.selectionData = (SimpleCategoriesData)data;
         assertDataValid();
     }
 
     private void assertDataValid () {
-        if (selectionData != null && allBallotQuestions != null) {
         int questionsLength = allBallotQuestions.length;
-            int maxQuestionNumber = selectionData.getMaxQuestionNumber();
+        int maxQuestionIndex = -1;
-            if (maxQuestionNumber >= questionsLength) {
+        for (int[][] categoryChooser: categoryChoosers) {
-                String errorMessage = "Selection data refers to question index " + maxQuestionNumber + " while we have only " + questionsLength + " questions totally";
+            for (int[] category: categoryChooser) {
+                for (int index: category) {
+                    maxQuestionIndex = Math.max(maxQuestionIndex, index);
+                }
+            }
+        }
+        if (maxQuestionIndex >= questionsLength) {
+            String errorMessage = "Selection data refers to question index " + maxQuestionIndex + " while we have only " + questionsLength + " questions totally";
             logger.error(errorMessage);
             throw new IndexOutOfBoundsException(errorMessage);
         }
     }
-    }
+
 
     @Override
-    public int getChannelIdentifier(List<BallotAnswer> channelChoiceAnswers) {
+    public byte[] getChannelIdentifier(List<BallotAnswer> channelChoiceAnswers) {
-        return 0;
+        byte[] isSelected = new byte[allBallotQuestions.length];
+        java.util.Arrays.fill(isSelected, QUESTION_NOT_SELECTED);
+
+        for (int i: sharedDefaults) {
+            isSelected[i] = QUESTION_SELECTED;
         }
 
-    @Override
+        int channelChoiceQuestionNumber = 0;
-    public List<BallotQuestion> selectQuestionsForVoter(List<BallotAnswer> channelChoiceAnswers) {
+        for (BallotAnswer ballotAnswer: channelChoiceAnswers) {
-        java.util.Arrays.fill(isSelected, false);
+            assertAnswerLengthIsOne(ballotAnswer, channelChoiceQuestionNumber);
-        markSelected(selectionData.getSharedDefaults());
+            for (int i: categoryChoosers[channelChoiceQuestionNumber][(int)ballotAnswer.getAnswer(0)]) {
-        markSelectionsOfVoterChannelChoice ((BallotAnswer[])channelChoiceAnswers.toArray());
+                isSelected[i] = QUESTION_SELECTED;
-        int[] questionIndices = extractSelectedIndices();
-        List<BallotQuestion> selectedQuestions = new ArrayList<>();
-        for (int questionIndex: questionIndices) {
-            selectedQuestions.add(allBallotQuestions[questionIndex]);
             }
-        return selectedQuestions;
         }
 
-    private void markSelectionsOfVoterChannelChoice(BallotAnswer[] channelChoiceAnswers) {
+        return isSelected;
-        for (int q = 0; q < channelChoiceAnswers.length; ++q) {
-            BallotAnswer ballotAnswer = channelChoiceAnswers[q];
-            assertAnswerLengthIsOne(ballotAnswer, q);
-            assertKeyInSelectionData(q, (int)ballotAnswer.getAnswer(0));
-            markSelected(selectionData.getItem(q, (int)ballotAnswer.getAnswer(0)));
-        }
     }
 
     private void assertAnswerLengthIsOne (BallotAnswer ballotAnswer, int questionNumber) {
@@ -98,35 +98,23 @@ public class SimpleListCategoriesSelector implements QuestionSelector {
         }
     }
 
-    private void assertKeyInSelectionData(int questionNumber, int answerNumber) {
+    @Override
-        int[] questionListToAdd = selectionData.getItem(questionNumber, answerNumber);
+    public List<BallotQuestion> selectQuestionsForVoter(byte[] channelIdentifier) {
-        if (null == questionListToAdd) {
+        List<BallotQuestion> selectedQuestions = new ArrayList<>();
-            String errorMessage = "SimpleListCategoriesSelector could not resolve answer number " + answerNumber + " for question number " + questionNumber;
+        for (int i = 0; i < channelIdentifier.length; ++i) {
-            logger.error(errorMessage);
+            if (channelIdentifier[i] == QUESTION_SELECTED) {
-            throw new IllegalArgumentException(errorMessage);
+                selectedQuestions.add(allBallotQuestions[i]);
             }
         }
+        return selectedQuestions;
+    }
 
-    private void markSelected (int[] questionIndices) {
+    private int[] listToIntArray(List<Integer> l) {
-        for (int i: questionIndices) {
+        int[] res = new int[l.size()];
-            isSelected[i] = true;
+        int index = 0;
-        }
+        for (Integer i: l) {
-    }
+            res[index] = i;
-
+            ++index;
-    private int[] extractSelectedIndices() {
-        int nSelected = 0;
-        for (boolean b: isSelected) {
-            if (b) {
-                nSelected++;
-            }
-        }
-        int[] res = new int[nSelected];
-        int currIndex = 0;
-        for (int questionNumber = 0; questionNumber < isSelected.length; ++questionNumber) {
-            if (isSelected[questionNumber]) {
-                res[currIndex] = questionNumber;
-                currIndex++;
-            }
         }
         return res;
     }

voting-booth/src/main/java/meerkat/voting/encryptor/VBCryptoManager.java

@@ -2,25 +2,27 @@ package meerkat.voting.encryptor;
 
 import meerkat.protobuf.Voting.*;
 
+import java.io.IOException;
+import java.security.SignatureException;
+
 /**
  * An interface for the encryptor component of the voting booth
  */
-public interface VotingBoothEncryptor {
+public interface VBCryptoManager {
-
     /**
      * A simple class for pairing EncrypedBallot together with its matching BallotSecrets
      */
     public class EncryptionAndSecrets {
-        private final EncryptedBallot encryptedBallot;
+        private final SignedEncryptedBallot signedEncryptedBallot;
         private final BallotSecrets secrets;
 
-        public EncryptionAndSecrets (EncryptedBallot encryptedBallot, BallotSecrets secrets) {
+        public EncryptionAndSecrets (SignedEncryptedBallot encryptedBallot, BallotSecrets secrets) {
-            this.encryptedBallot = encryptedBallot;
+            this.signedEncryptedBallot = encryptedBallot;
             this.secrets = secrets;
         }
 
-        public EncryptedBallot getEncryptedBallot ()  {
+        public SignedEncryptedBallot getSignedEncryptedBallot()  {
-            return encryptedBallot;
+            return signedEncryptedBallot;
         }
 
         public BallotSecrets getSecrets()  {
@@ -34,8 +36,7 @@ public interface VotingBoothEncryptor {
      * @param plaintextBallot - all plaintext ballot info of the voter
      * @return an encryption of the ballot
      */
-    public EncryptionAndSecrets encrypt (PlaintextBallot plaintextBallot);
+    public EncryptionAndSecrets encrypt (PlaintextBallot plaintextBallot) throws SignatureException, IOException;
 
 
-    //TODO: probably needs some key generation methods as well
 }

voting-booth/src/main/java/meerkat/voting/encryptor/VBCryptoManagerImpl.java

@@ -0,0 +1,67 @@
+package meerkat.voting.encryptor;
+
+import meerkat.crypto.*;
+import meerkat.protobuf.Crypto.*;
+import meerkat.protobuf.Voting.*;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.security.SignatureException;
+import java.util.Random;
+
+/**
+ * Created by hai on 07/06/16.
+ */
+public class VBCryptoManagerImpl implements VBCryptoManager {
+
+    protected final static Logger logger = LoggerFactory.getLogger(VBCryptoManagerImpl.class);
+
+    private final Random random;
+    private final Encryption encryption;
+    private final DigitalSignature digitalSignature;
+
+
+    public VBCryptoManagerImpl (Random rand, Encryption encryption, DigitalSignature digitalSignature) {
+        this.random = rand;
+        this.encryption = encryption;
+        this.digitalSignature = digitalSignature;
+    }
+
+
+    @Override
+    public EncryptionAndSecrets encrypt(PlaintextBallot plaintextBallot) throws SignatureException, IOException {
+
+        // TODO: do we seed the random here?
+
+        try {
+            EncryptionRandomness encryptionRandomness = encryption.generateRandomness(random);
+            BallotSecrets secrets = BallotSecrets.newBuilder()
+                    .setPlaintextBallot(plaintextBallot)
+                    .setEncryptionRandomness(encryptionRandomness)
+                    .build();
+            RerandomizableEncryptedMessage encryptedMessage = encryption.encrypt(plaintextBallot, encryptionRandomness);
+            EncryptedBallot encBallot = EncryptedBallot.newBuilder()
+                    .setSerialNumber(plaintextBallot.getSerialNumber())
+                    .setData(encryptedMessage)
+                    .build();
+            digitalSignature.updateContent(encBallot);
+
+            SignedEncryptedBallot signedEncryptedBallot = SignedEncryptedBallot.newBuilder()
+                    .setEncryptedBallot(encBallot)
+                    .setSignerId(digitalSignature.getSignerID())
+                    .setSignature(digitalSignature.sign())
+                    .build();
+
+            return new EncryptionAndSecrets(signedEncryptedBallot, secrets);
+        }
+        catch (IOException e) {
+            logger.error("encrypt: the encryption component has thrown an exception: " + e);
+            throw e;
+        }
+        catch (SignatureException e) {
+            logger.error("encrypt: the signature component has thrown an exception: " + e);
+            throw e;
+        }
+    }
+}

voting-booth/src/main/java/meerkat/voting/encryptor/VBEncryptorImpl.java

@@ -1,14 +0,0 @@
-package meerkat.voting.encryptor;
-
-import meerkat.protobuf.Voting.*;
-
-/**
- * Created by hai on 26/04/16.
- */
-public class VBEncryptorImpl implements VotingBoothEncryptor {
-
-    @Override
-    public EncryptionAndSecrets encrypt(PlaintextBallot plaintextBallot) {
-        throw new UnsupportedOperationException();
-    }
-}

voting-booth/src/main/java/meerkat/voting/output/BallotOutputDevice.java

@@ -15,7 +15,7 @@ public interface BallotOutputDevice {
      * @param callback - a callback object which expects no return value
      */
     public void commitToBallot(PlaintextBallot plaintextBallot,
-                               EncryptedBallot encryptedBallot,
+                               SignedEncryptedBallot encryptedBallot,
                                FutureCallback<Void> callback);
 
     /**

voting-booth/src/main/java/meerkat/voting/output/SystemConsoleOutputDevice.java

@@ -29,18 +29,18 @@ public class SystemConsoleOutputDevice implements BallotOutputDevice {
 
     @Override
     public void commitToBallot(PlaintextBallot plaintextBallot,
-                               EncryptedBallot encryptedBallot,
+                               SignedEncryptedBallot signedEncryptedBallot,
                                FutureCallback<Void> callback) {
         logger.debug("entered method commitToBallot");
         long plaintextSerialNumber = plaintextBallot.getSerialNumber();
         System.out.println("Commitment of Ballot #" + plaintextSerialNumber + " (plaintext):");
-        long encryptedSerialNumber = encryptedBallot.getSerialNumber();
+        long encryptedSerialNumber = signedEncryptedBallot.getEncryptedBallot().getSerialNumber();
         System.out.println("Commitment of Ballot #" + encryptedSerialNumber + " (ciphertext):");
         if (plaintextSerialNumber != encryptedSerialNumber) {
             logger.error("plaintext and encryption serial numbers do not match!! plaintext# = " +
                     plaintextSerialNumber + ", ciphertext# = " + encryptedSerialNumber);
         }
-        ByteString encryptedData = encryptedBallot.getData().getData();
+        ByteString encryptedData = signedEncryptedBallot.getEncryptedBallot().getData().getData();
         System.out.println(bytesToString(encryptedData));
         callback.onSuccess(null);
     }

voting-booth/src/main/java/meerkat/voting/ui/SystemConsoleUI.java

@@ -26,6 +26,9 @@ public class SystemConsoleUI implements VotingBoothUI, Runnable {
     private final int tickDurationInMillisec = 10;
     private Date startWaitingTime;
 
+    private volatile boolean shutDownHasBeenCalled;
+
+
 
     public SystemConsoleUI() {
         logger = LoggerFactory.getLogger(SystemConsoleUI.class);
@@ -36,12 +39,15 @@ public class SystemConsoleUI implements VotingBoothUI, Runnable {
         startWaitingTime = null;
         Timer timer = new Timer();
         timer.scheduleAtFixedRate(new TickerTimerTask(queue), new Date(), tickDurationInMillisec);
+
+        shutDownHasBeenCalled = false;
     }
 
 
+    @Override
     public void run () {
         logger.info("entered the voting flow");
-        while (true) {
+        while (! wasShutDownCalled()) {
             try {
                 UICommand command = queue.take();
                 handleSingleCommand(command);
@@ -53,6 +59,13 @@ public class SystemConsoleUI implements VotingBoothUI, Runnable {
     }
 
 
+    @Override
+    public void callShutDown() {
+        logger.info("callShutDown command has been called");
+        shutDownHasBeenCalled = true;
+        queue.clear();
+    }
+
     private void handleSingleCommand(UICommand command) {
         if (!(command instanceof TickCommand)) {
             if (startWaitingTime != null) {
@@ -142,6 +155,9 @@ public class SystemConsoleUI implements VotingBoothUI, Runnable {
             List<BallotAnswer> answers = askVoterForAnswers(command.getQuestions());
             command.getCallback().onSuccess(answers);
         }
+        catch (VoterCancelException e) {
+            command.getCallback().onFailure(e);
+        }
         catch (IOException e) {
             String errorMessage = "Channel choice failed due to IOException: " + e;
             logger.error (errorMessage);
@@ -163,6 +179,9 @@ public class SystemConsoleUI implements VotingBoothUI, Runnable {
             List<BallotAnswer> answers = askVoterForAnswers(command.getQuestions());
             command.getCallback().onSuccess(answers);
         }
+        catch (VoterCancelException e) {
+            command.getCallback().onFailure(e);
+        }
         catch (IOException e) {
             String errorMessage = "Asking voting questions failed due to IOException: " + e;
             logger.error (errorMessage);
@@ -320,7 +339,7 @@ public class SystemConsoleUI implements VotingBoothUI, Runnable {
         }
     }
 
-    private List<BallotAnswer> askVoterForAnswers(List<BallotQuestion> questions) throws IOException {
+    private List<BallotAnswer> askVoterForAnswers(List<BallotQuestion> questions) throws VoterCancelException, IOException {
 
         assertQuestionsAreValid (questions);
 
@@ -335,7 +354,7 @@ public class SystemConsoleUI implements VotingBoothUI, Runnable {
             String s = readInputLine();
 
             if ((s.equals("cancel") || s.equals("c")) || (index == 0 && (s.equals("back") || s.equals("b")))) {
-                return null;
+                throw new VoterCancelException();
             }
             else if (s.equals("back") || s.equals("b")) {
                 --index;
@@ -400,4 +419,10 @@ public class SystemConsoleUI implements VotingBoothUI, Runnable {
         return data.toStringUtf8();
     }
 
+
+    private boolean wasShutDownCalled () {
+        return shutDownHasBeenCalled;
+    }
+
+
 }

voting-booth/src/main/java/meerkat/voting/ui/VotingBoothUI.java

@@ -16,6 +16,11 @@ public interface VotingBoothUI {
         AUDIT
     }
 
+    /**
+     * shut down the UI
+     */
+    public void callShutDown();
+
     /**
      * Starts a new session for a voter. Presents whatever initial info is decided to show at the beginning
      * @param callback - a boolean future callback to return when done