qr code display and random sampler port

src/main/java/com/sparrowwallet/sparrow/control/QRDisplayDialog.java

@@ -0,0 +1,112 @@
+package com.sparrowwallet.sparrow.control;
+
+import com.google.zxing.BarcodeFormat;
+import com.google.zxing.client.j2se.MatrixToImageConfig;
+import com.google.zxing.client.j2se.MatrixToImageWriter;
+import com.google.zxing.common.BitMatrix;
+import com.google.zxing.qrcode.QRCodeWriter;
+import com.sparrowwallet.sparrow.EventManager;
+import com.sparrowwallet.sparrow.io.ImportException;
+import com.sparrowwallet.sparrow.ur.UR;
+import com.sparrowwallet.sparrow.ur.UREncoder;
+import javafx.concurrent.ScheduledService;
+import javafx.concurrent.Task;
+import javafx.scene.control.ButtonBar;
+import javafx.scene.control.ButtonType;
+import javafx.scene.control.Dialog;
+import javafx.scene.control.DialogPane;
+import javafx.scene.image.Image;
+import javafx.scene.image.ImageView;
+import javafx.scene.layout.StackPane;
+import javafx.util.Duration;
+import org.controlsfx.tools.Borders;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+
+public class QRDisplayDialog extends Dialog<UR> {
+    private static final int MIN_FRAGMENT_LENGTH = 10;
+    private static final int MAX_FRAGMENT_LENGTH = 100;
+
+    private final UR ur;
+    private final UREncoder encoder;
+
+    private final ImageView qrImageView;
+
+    private String currentPart;
+
+    public QRDisplayDialog(byte[] data) {
+        this(UR.fromBytes(data));
+    }
+
+    public QRDisplayDialog(UR ur) {
+        this.ur = ur;
+        this.encoder = new UREncoder(ur, MAX_FRAGMENT_LENGTH, MIN_FRAGMENT_LENGTH, 0);
+
+        EventManager.get().register(this);
+
+        final DialogPane dialogPane = getDialogPane();
+
+        StackPane stackPane = new StackPane();
+        qrImageView = new ImageView();
+        stackPane.getChildren().add(qrImageView);
+
+        dialogPane.setContent(Borders.wrap(stackPane).lineBorder().outerPadding(0).innerPadding(0).buildAll());
+
+        nextPart();
+        if(encoder.isSinglePart()) {
+            qrImageView.setImage(getQrCode(currentPart));
+        } else {
+            AnimateQRService animateQRService = new AnimateQRService();
+            animateQRService.setPeriod(Duration.millis(100));
+            animateQRService.start();
+            setOnCloseRequest(event -> {
+                animateQRService.cancel();
+            });
+        }
+
+        final ButtonType cancelButtonType = new javafx.scene.control.ButtonType("Cancel", ButtonBar.ButtonData.CANCEL_CLOSE);
+        dialogPane.getButtonTypes().addAll(cancelButtonType);
+        dialogPane.setPrefWidth(500);
+        dialogPane.setPrefHeight(550);
+
+        setResultConverter(dialogButton -> dialogButton != cancelButtonType ? ur : null);
+    }
+
+    private void nextPart() {
+        String fragment = encoder.nextPart();
+        currentPart = fragment.toUpperCase();
+    }
+
+    private Image getQrCode(String fragment) {
+        try {
+            QRCodeWriter qrCodeWriter = new QRCodeWriter();
+            BitMatrix qrMatrix = qrCodeWriter.encode(fragment, BarcodeFormat.QR_CODE, 480, 480);
+
+            ByteArrayOutputStream baos = new ByteArrayOutputStream();
+            MatrixToImageWriter.writeToStream(qrMatrix, "PNG", baos, new MatrixToImageConfig());
+
+            ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
+            return new Image(bais);
+        } catch(Exception e) {
+            e.printStackTrace();
+        }
+
+        return null;
+    }
+
+    private class AnimateQRService extends ScheduledService<Boolean> {
+        @Override
+        protected Task<Boolean> createTask() {
+            return new Task<>() {
+                protected Boolean call() throws ImportException {
+                    Image qrImage = getQrCode(currentPart);
+                    qrImageView.setImage(qrImage);
+                    nextPart();
+
+                    return true;
+                }
+            };
+        }
+    }
+}

src/main/java/com/sparrowwallet/sparrow/transaction/HeadersController.java

@@ -530,7 +530,8 @@ public class HeadersController extends TransactionFormController implements Init
         ToggleButton toggleButton = (ToggleButton)event.getSource();
         toggleButton.setSelected(false);
 
-        headersForm.getSignedKeystores().add(headersForm.getSigningWallet().getKeystores().get(0));
+        QRDisplayDialog qrDisplayDialog = new QRDisplayDialog(headersForm.getPsbt().serialize());
+        qrDisplayDialog.show();
     }
 
     public void scanPSBT(ActionEvent event) {

src/main/java/com/sparrowwallet/sparrow/ur/UR.java

@@ -43,6 +43,14 @@ public class UR {
         return false;
     }
 
+    public static UR fromBytes(byte[] data) {
+        try {
+            return new UR("bytes", data);
+        } catch(UR.InvalidTypeException e) {
+            return null;
+        }
+    }
+
     @Override
     public boolean equals(Object o) {
         if(this == o) {

src/main/java/com/sparrowwallet/sparrow/ur/fountain/AliasMethod.java

@@ -1,149 +0,0 @@
-package com.sparrowwallet.sparrow.ur.fountain;
-
-/******************************************************************************
- * File: AliasMethod.java
- * Author: Keith Schwarz (htiek@cs.stanford.edu)
- *
- * An implementation of the alias method implemented using Vose's algorithm.
- * The alias method allows for efficient sampling of random values from a
- * discrete probability distribution (i.e. rolling a loaded die) in O(1) time
- * each after O(n) preprocessing time.
- *
- * For a complete writeup on the alias method, including the intuition and
- * important proofs, please see the article "Darts, Dice, and Coins: Smpling
- * from a Discrete Distribution" at
- *
- *                 http://www.keithschwarz.com/darts-dice-coins/
- */
-import java.util.*;
-
-public final class AliasMethod {
-    /* The random number generator used to sample from the distribution. */
-    private final Random random;
-
-    /* The probability and alias tables. */
-    private final int[] alias;
-    private final double[] probability;
-
-    /**
-     * Constructs a new AliasMethod to sample from a discrete distribution and
-     * hand back outcomes based on the probability distribution.
-     * <p>
-     * Given as input a list of probabilities corresponding to outcomes 0, 1,
-     * ..., n - 1, this constructor creates the probability and alias tables
-     * needed to efficiently sample from this distribution.
-     *
-     * @param probabilities The list of probabilities.
-     */
-    public AliasMethod(List<Double> probabilities) {
-        this(probabilities, new Random());
-    }
-
-    /**
-     * Constructs a new AliasMethod to sample from a discrete distribution and
-     * hand back outcomes based on the probability distribution.
-     * <p>
-     * Given as input a list of probabilities corresponding to outcomes 0, 1,
-     * ..., n - 1, along with the random number generator that should be used
-     * as the underlying generator, this constructor creates the probability
-     * and alias tables needed to efficiently sample from this distribution.
-     *
-     * @param probabilities The list of probabilities.
-     * @param random The random number generator
-     */
-    public AliasMethod(List<Double> probabilities, Random random) {
-        /* Begin by doing basic structural checks on the inputs. */
-        if (probabilities == null || random == null)
-            throw new NullPointerException();
-        if (probabilities.size() == 0)
-            throw new IllegalArgumentException("Probability vector must be nonempty.");
-
-        /* Allocate space for the probability and alias tables. */
-        probability = new double[probabilities.size()];
-        alias = new int[probabilities.size()];
-
-        /* Store the underlying generator. */
-        this.random = random;
-
-        /* Compute the average probability and cache it for later use. */
-        final double average = 1.0 / probabilities.size();
-
-        /* Make a copy of the probabilities list, since we will be making
-         * changes to it.
-         */
-        probabilities = new ArrayList<Double>(probabilities);
-
-        /* Create two stacks to act as worklists as we populate the tables. */
-        Deque<Integer> small = new ArrayDeque<Integer>();
-        Deque<Integer> large = new ArrayDeque<Integer>();
-
-        /* Populate the stacks with the input probabilities. */
-        for (int i = 0; i < probabilities.size(); ++i) {
-            /* If the probability is below the average probability, then we add
-             * it to the small list; otherwise we add it to the large list.
-             */
-            if (probabilities.get(i) >= average)
-                large.add(i);
-            else
-                small.add(i);
-        }
-
-        /* As a note: in the mathematical specification of the algorithm, we
-         * will always exhaust the small list before the big list.  However,
-         * due to floating point inaccuracies, this is not necessarily true.
-         * Consequently, this inner loop (which tries to pair small and large
-         * elements) will have to check that both lists aren't empty.
-         */
-        while (!small.isEmpty() && !large.isEmpty()) {
-            /* Get the index of the small and the large probabilities. */
-            int less = small.removeLast();
-            int more = large.removeLast();
-
-            /* These probabilities have not yet been scaled up to be such that
-             * 1/n is given weight 1.0.  We do this here instead.
-             */
-            probability[less] = probabilities.get(less) * probabilities.size();
-            alias[less] = more;
-
-            /* Decrease the probability of the larger one by the appropriate
-             * amount.
-             */
-            probabilities.set(more,
-                    (probabilities.get(more) + probabilities.get(less)) - average);
-
-            /* If the new probability is less than the average, add it into the
-             * small list; otherwise add it to the large list.
-             */
-            if (probabilities.get(more) >= 1.0 / probabilities.size())
-                large.add(more);
-            else
-                small.add(more);
-        }
-
-        /* At this point, everything is in one list, which means that the
-         * remaining probabilities should all be 1/n.  Based on this, set them
-         * appropriately.  Due to numerical issues, we can't be sure which
-         * stack will hold the entries, so we empty both.
-         */
-        while (!small.isEmpty())
-            probability[small.removeLast()] = 1.0;
-        while (!large.isEmpty())
-            probability[large.removeLast()] = 1.0;
-    }
-
-    /**
-     * Samples a value from the underlying distribution.
-     *
-     * @return A random value sampled from the underlying distribution.
-     */
-    public int next() {
-        /* Generate a fair die roll to determine which column to inspect. */
-        int column = random.nextInt(probability.length);
-
-        /* Generate a biased coin toss to determine which option to pick. */
-        boolean coinToss = random.nextDouble() < probability[column];
-
-        /* Based on the outcome, return either the column or its alias. */
-        return coinToss? column : alias[column];
-    }
-}

src/main/java/com/sparrowwallet/sparrow/ur/fountain/FountainUtils.java

@@ -31,8 +31,8 @@ public class FountainUtils {
 
     static int chooseDegree(int seqLen, RandomXoshiro256StarStar rng) {
         List<Double> degreeProbabilties = IntStream.range(1, seqLen + 1).mapToObj(i -> 1 / (double)i).collect(Collectors.toList());
-        AliasMethod degreeChooser = new AliasMethod(degreeProbabilties, rng);
+        RandomSampler randomSampler = new RandomSampler(degreeProbabilties);
-        return degreeChooser.next() + 1;
+        return randomSampler.next(rng) + 1;
     }
 
     static List<Integer> shuffled(List<Integer> indexes, RandomXoshiro256StarStar rng) {

src/main/java/com/sparrowwallet/sparrow/ur/fountain/RandomSampler.java

@@ -0,0 +1,84 @@
+package com.sparrowwallet.sparrow.ur.fountain;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+import java.util.stream.Collectors;
+
+/**
+ * Random-number sampling using the Walker-Vose alias method,
+ * as described by Keith Schwarz (2011)
+ * http://www.keithschwarz.com/darts-dice-coins
+ *
+ * Based on C implementation:
+ * https://jugit.fz-juelich.de/mlz/ransampl
+ *
+ * Ported from https://github.com/BlockchainCommons/URKit
+ */
+public class RandomSampler {
+    /* The probability and alias tables. */
+    private final double[] probs;
+    private final int[] aliases;
+
+    public RandomSampler(List<Double> probabilities) {
+        if(probabilities.stream().anyMatch(prob -> prob < 0)) {
+            throw new IllegalArgumentException("Probabilties must be > 0");
+        }
+
+        // Normalize given probabilities
+        double sum = probabilities.stream().reduce(0d, Double::sum);
+
+        int n = probabilities.size();
+        List<Double> P = probabilities.stream().map(prob -> prob * (double)n / sum).collect(Collectors.toList());
+
+        List<Integer> S = new ArrayList<>();
+        List<Integer> L = new ArrayList<>();
+
+        // Set separate index lists for small and large probabilities:
+        for(int i = n - 1; i >= 0; i--) {
+            // at variance from Schwarz, we reverse the index order
+            if(P.get(i) < 1d) {
+                S.add(i);
+            } else {
+                L.add(i);
+            }
+        }
+
+        // Work through index lists
+        double[] probs = new double[n];
+        int[] aliases = new int[n];
+
+        while(!S.isEmpty() && !L.isEmpty()) {
+            int a = S.remove(S.size() - 1);
+            int g = L.remove(L.size() - 1);
+            probs[a] = P.get(a);
+            aliases[a] = g;
+            P.set(g, P.get(g) + P.get(a) - 1);
+            if(P.get(g) < 1) {
+                S.add(g);
+            } else {
+                L.add(g);
+            }
+        }
+
+        while(!L.isEmpty()) {
+            probs[L.remove(L.size() - 1)] = 1;
+        }
+
+        while(!S.isEmpty()) {
+            // can only happen through numeric instability
+            probs[S.remove(S.size() - 1)] = 1;
+        }
+
+        this.probs = probs;
+        this.aliases = aliases;
+    }
+
+    public int next(Random random) {
+        double r1 = random.nextDouble();
+        double r2 = random.nextDouble();
+        int n = probs.length;
+        int i = (int)((double)n * r1);
+        return r2 < probs[i] ? i : aliases[i];
+    }
+}

src/test/java/com/sparrowwallet/sparrow/ur/URTest.java

@@ -3,13 +3,11 @@ package com.sparrowwallet.sparrow.ur;
 import co.nstant.in.cbor.CborBuilder;
 import co.nstant.in.cbor.CborEncoder;
 import com.sparrowwallet.drongo.Utils;
-import com.sparrowwallet.sparrow.ur.fountain.FountainEncoder;
 import com.sparrowwallet.sparrow.ur.fountain.RandomXoshiro256StarStar;
 import org.junit.Assert;
 import org.junit.Test;
 
 import java.io.ByteArrayOutputStream;
-import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
@@ -37,17 +35,17 @@ public class URTest {
                 "ur:bytes/7-9/ltatascfadaxcywenbpljkhdcavszownjkwtclrtvaynhpahrtoxmwvwatmedibkaegdosftvandiodagdhthtrlnnhy",
                 "ur:bytes/8-9/ltayascfadaxcywenbpljkhdcadmsponkkbbhgsolnjntegepmttmoonftnbuoiyrehfrtsabzsttorodklubbuyaetk",
                 "ur:bytes/9-9/ltasascfadaxcywenbpljkhdcajskecpmdckihdyhphfotjojtfmlpwmadspaxrkytbztpbauotbgtgtaeaevtgavtny",
-                "ur:bytes/10-9/ltbkascfadaxcywenbpljkhdcazoqdayfeaavsnnrffhjnfytplguytsoyspgdrhluheihtyettewtytcfrtdeahhdad",
+                "ur:bytes/10-9/ltbkascfadaxcywenbpljkhdcahkadaemejtswhhylkepmykhhtsytsnoyoyaxaedsuttydmmhhpktpmsrjtwdkiplzs",
-                "ur:bytes/11-9/ltbdascfadaxcywenbpljkhdcavdintbiyjltafyknfspefrvdondtvlgdckfslthkgtghsbsbbtiyechthdlakobtfd",
+                "ur:bytes/11-9/ltbdascfadaxcywenbpljkhdcahelbknlkuejnbadmssfhfrdpsbiegecpasvssovlgeykssjykklronvsjkvetiiapk",
-                "ur:bytes/12-9/ltbnascfadaxcywenbpljkhdcalndikttpecueksoecypdssvtplkiryjydioefywyrtjlsedppagwpseturfhbzmdmd",
+                "ur:bytes/12-9/ltbnascfadaxcywenbpljkhdcarllaluzodmgstospeyiefmwejlwtpedamktksrvlcygmzmmovovllarodtmtbnptrs",
-                "ur:bytes/13-9/ltbtascfadaxcywenbpljkhdcazoqdayfeaavsnnrffhjnfytplguytsoyspgdrhluheihtyettewtytcfrtutwtoyon",
+                "ur:bytes/13-9/ltbtascfadaxcywenbpljkhdcamtkgtpknghchchyketwsvwgwfdhpgmgtylctotztpdrpayoschcmhplffziachrfgd",
-                "ur:bytes/14-9/ltbaascfadaxcywenbpljkhdcanbsfjpsotnltmhmoztgmlbykfgrsntlsserojoisbzmhbegspkjyhhwnqdfneobkfd",
+                "ur:bytes/14-9/ltbaascfadaxcywenbpljkhdcapazmwnvonnvdnsbyleynwtnsjkjndeoldydkbkdslgjkbbkortbelomueekgvstegt",
                 "ur:bytes/15-9/ltbsascfadaxcywenbpljkhdcaynmhpddpzoversbdqdfyrehnqzlugmjzmnmtwmrouohtstgsbsahpawkditkckynwt",
-                "ur:bytes/16-9/ltbeascfadaxcywenbpljkhdcazoqdayfeaavsnnrffhjnfytplguytsoyspgdrhluheihtyettewtytcfrtghtduycm",
+                "ur:bytes/16-9/ltbeascfadaxcywenbpljkhdcawygekobamwtlihsnpalpsghenskkiynthdzttsimtojetprsttmukirlrsbtamjtpd",
-                "ur:bytes/17-9/ltbyascfadaxcywenbpljkhdcarpfeneknvyyadifltalghskpgrfgsngulagspfpthyrpgrsoatjnuyflvsdmpyinmw",
+                "ur:bytes/17-9/ltbyascfadaxcywenbpljkhdcamklgftaxykpewyrtqzhydntpnytyisincxmhtbceaykolduortotiaiaiafhiaoyce",
-                "ur:bytes/18-9/ltbgascfadaxcywenbpljkhdcavtrfmwktecjnnsyafsemaaspglynhhrhmyjyoelgjtpyhkssamdsfehfnsfrcfrnyk",
+                "ur:bytes/18-9/ltbgascfadaxcywenbpljkhdcahkadaemejtswhhylkepmykhhtsytsnoyoyaxaedsuttydmmhhpktpmsrjtntwkbkwy",
-                "ur:bytes/19-9/ltbwascfadaxcywenbpljkhdcaenbgkghtlbiybwfpjlbyecmoythnmesbkopahtiofywnutvacfhdjyiobwrtlbtbme",
+                "ur:bytes/19-9/ltbwascfadaxcywenbpljkhdcadekicpaajootjzpsdrbalteywllbdsnbinaerkurspbncxgslgftvtsrjtksplcpeo",
-                "ur:bytes/20-9/ltbbascfadaxcywenbpljkhdcarssrwyztwmaemotbytayfhvwltmocmndlpnsjejtdkhyntpflboevtrnwsdkjssbrs"
+                "ur:bytes/20-9/ltbbascfadaxcywenbpljkhdcayapmrleeleaxpasfrtrdkncffwjyjzgyetdmlewtkpktgllepfrltatazcksmhkbot"
         };
         Assert.assertArrayEquals("", expectedParts, parts.toArray());
     }
@@ -70,37 +68,6 @@ public class URTest {
         Assert.assertEquals(ur, decodedUR);
     }
 
-    @Test
-    public void testEncoderCBOR() {
-        byte[] message = makeMessage(256, "Wolf");
-        FountainEncoder fountainEncoder = new FountainEncoder(message, 30, 10, 0);
-        FountainEncoder.Part[] parts = IntStream.range(0, 20).mapToObj(i -> fountainEncoder.nextPart()).collect(Collectors.toList()).toArray(new FountainEncoder.Part[20]);
-        List<String> partsHex = Arrays.stream(parts).map(part -> Utils.bytesToHex(part.toCborBytes())).collect(Collectors.toList());
-        String[] expectedPartsHex = new String[] {
-                "8501091901001a0167aa07581d916ec65cf77cadf55cd7f9cda1a1030026ddd42e905b77adc36e4f2d3c",
-                "8502091901001a0167aa07581dcba44f7f04f2de44f42d84c374a0e149136f25b01852545961d55f7f7a",
-                "8503091901001a0167aa07581d8cde6d0e2ec43f3b2dcb644a2209e8c9e34af5c4747984a5e873c9cf5f",
-                "8504091901001a0167aa07581d965e25ee29039fdf8ca74f1c769fc07eb7ebaec46e0695aea6cbd60b3e",
-                "8505091901001a0167aa07581dc4bbff1b9ffe8a9e7240129377b9d3711ed38d412fbb4442256f1e6f59",
-                "8506091901001a0167aa07581d5e0fc57fed451fb0a0101fb76b1fb1e1b88cfdfdaa946294a47de8fff1",
-                "8507091901001a0167aa07581d73f021c0e6f65b05c0a494e50791270a0050a73ae69b6725505a2ec8a5",
-                "8508091901001a0167aa07581d791457c9876dd34aadd192a53aa0dc66b556c0c215c7ceb8248b717c22",
-                "8509091901001a0167aa07581d951e65305b56a3706e3e86eb01c803bbf915d80edcd64d4d0000000000",
-                "850a091901001a0167aa07581d4a1b58fa2733399e5ee04d87a2d1628186e3cd250f3ae0e25d7ae7a22b",
-                "850b091901001a0167aa07581dd35acd70953cf29b542a94cbd75790c73cb4cb1056d56557bf0b70b936",
-                "850c091901001a0167aa07581d8cde6d0e2ec43f3b2dcb644a2209e8c9e34af5c4747984a5e873c9cf5f",
-                "850d091901001a0167aa07581d760be7ad1c6187902bbc04f539b9ee5eb8ea6833222edea36031306c01",
-                "850e091901001a0167aa07581dcba44f7f04f2de44f42d84c374a0e149136f25b01852545961d55f7f7a",
-                "850f091901001a0167aa07581d262518878e747c6eee337fbbd189f77b385efe55597b54cab65b7f8ac0",
-                "8510091901001a0167aa07581d2d4a0b8fb95226315ab796cd72f9c5f8ea2a5a84221f7e31318f71b7df",
-                "8511091901001a0167aa07581d81bf178523c1e7daaacdc944d67183c8958ce8951768b4bb3cafb8dd51",
-                "8512091901001a0167aa07581d8e1548d10a2cd18416a3428bcb1fe2e3cac640274e91df20bdbd4e4df9",
-                "8513091901001a0167aa07581d8a65ebbda606df01244a3dad6b76e258150e4c07021ce5c07ed30160c5",
-                "8514091901001a0167aa07581d2b44620c8371a48f6935d2b525f19c7a4e98e3043a6a64d462870e98ce"};
-
-        Assert.assertEquals(Arrays.asList(expectedPartsHex), partsHex);
-    }
-
     public static byte[] makeMessage(int len, String seed) {
         RandomXoshiro256StarStar rng = new RandomXoshiro256StarStar(seed);
         byte[] message = new byte[len];

src/test/java/com/sparrowwallet/sparrow/ur/fountain/FountainCodesTest.java

@@ -11,6 +11,7 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
+import java.util.zip.CRC32;
 
 public class FountainCodesTest {
     @Test
@@ -25,9 +26,9 @@ public class FountainCodesTest {
     @Test
     public void testRandomSampler() {
         RandomXoshiro256StarStar rng = new RandomXoshiro256StarStar("Wolf");
-        AliasMethod aliasMethod = new AliasMethod(List.of(1d, 2d, 4d, 8d), rng);
+        RandomSampler randomSampler = new RandomSampler(List.of(1d, 2d, 4d, 8d));
-        int[] numbers = IntStream.range(0, 500).map(i -> aliasMethod.next()).toArray();
+        int[] numbers = IntStream.range(0, 500).map(i -> randomSampler.next(rng)).toArray();
-        int[] expectedNumbers = new int[] {2, 1, 2, 0, 2, 2, 0, 1, 0, 1, 1, 2, 1, 2, 3, 3, 1, 2, 0, 1, 0, 1, 0, 0, 0, 1, 1, 1, 3, 0, 1, 0, 2, 0, 1, 3, 3, 0, 3, 1, 2, 1, 2, 2, 0, 3, 2, 3, 2, 3, 1, 3, 1, 1, 0, 0, 1, 0, 0, 3, 0, 0, 2, 1, 2, 3, 3, 3, 3, 2, 0, 2, 3, 0, 0, 3, 1, 0, 2, 1, 1, 3, 0, 0, 2, 1, 1, 3, 3, 1, 3, 0, 1, 1, 0, 1, 0, 0, 1, 0, 3, 2, 2, 2, 1, 1, 0, 1, 3, 1, 0, 3, 3, 1, 3, 2, 1, 2, 2, 1, 3, 3, 3, 3, 2, 0, 0, 2, 2, 0, 2, 2, 1, 3, 2, 1, 2, 2, 2, 3, 0, 2, 1, 3, 1, 3, 1, 3, 0, 2, 2, 3, 2, 3, 1, 1, 1, 2, 3, 0, 1, 2, 3, 1, 2, 2, 1, 3, 3, 3, 2, 1, 0, 1, 1, 3, 2, 2, 3, 0, 0, 2, 0, 1, 0, 2, 2, 2, 1, 0, 2, 1, 2, 1, 3, 0, 0, 1, 0, 0, 0, 0, 1, 2, 1, 0, 1, 3, 1, 1, 3, 2, 1, 0, 2, 2, 0, 1, 1, 3, 0, 3, 3, 0, 1, 3, 3, 1, 2, 1, 1, 1, 2, 3, 2, 2, 1, 3, 2, 1, 3, 0, 2, 2, 0, 1, 3, 3, 0, 1, 1, 2, 3, 0, 2, 3, 1, 2, 1, 0, 2, 2, 0, 1, 2, 1, 3, 3, 0, 0, 3, 1, 2, 2, 0, 0, 2, 1, 1, 3, 2, 0, 3, 0, 0, 3, 0, 0, 3, 2, 2, 3, 3, 3, 3, 3, 3, 2, 1, 2, 2, 0, 2, 3, 3, 1, 3, 2, 1, 3, 2, 0, 0, 0, 0, 1, 0, 3, 1, 1, 1, 0, 0, 3, 0, 1, 1, 3, 2, 3, 3, 3, 2, 2, 2, 2, 0, 2, 2, 0, 2, 3, 2, 0, 3, 2, 2, 3, 3, 0, 3, 0, 2, 1, 2, 1, 0, 2, 2, 0, 0, 0, 0, 3, 0, 3, 0, 2, 3, 0, 3, 3, 3, 3, 3, 2, 3, 1, 2, 1, 0, 3, 0, 0, 1, 3, 0, 0, 0, 1, 3, 0, 3, 1, 0, 3, 2, 3, 0, 0, 1, 1, 3, 1, 3, 3, 1, 1, 2, 3, 3, 0, 0, 0, 2, 2, 2, 2, 1, 0, 2, 2, 3, 2, 2, 0, 2, 3, 2, 0, 3, 0, 1, 2, 2, 0, 2, 3, 0, 0, 2, 0, 3, 0, 1, 1, 3, 2, 2, 2, 0, 1, 2, 3, 3, 2, 2, 1, 2, 3, 1, 1, 1, 0, 3, 3, 0, 1, 2, 1, 0, 3, 2, 0, 3, 1, 1, 2, 2, 0, 1, 3, 0, 1, 3, 0, 0, 2, 0, 3, 0, 1, 2, 2, 0, 3, 1, 2, 0, 2};
+        int[] expectedNumbers = new int[] {3, 3, 3, 3, 3, 3, 3, 0, 2, 3, 3, 3, 3, 1, 2, 2, 1, 3, 3, 2, 3, 3, 1, 1, 2, 1, 1, 3, 1, 3, 1, 2, 0, 2, 1, 0, 3, 3, 3, 1, 3, 3, 3, 3, 1, 3, 2, 3, 2, 2, 3, 3, 3, 3, 2, 3, 3, 0, 3, 3, 3, 3, 1, 2, 3, 3, 2, 2, 2, 1, 2, 2, 1, 2, 3, 1, 3, 0, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 1, 3, 3, 2, 0, 2, 2, 3, 1, 1, 2, 3, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 2, 3, 1, 2, 1, 1, 3, 1, 3, 2, 2, 3, 3, 3, 1, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 2, 3, 3, 1, 2, 3, 3, 1, 3, 2, 3, 3, 3, 2, 3, 1, 3, 0, 3, 2, 1, 1, 3, 1, 3, 2, 3, 3, 3, 3, 2, 0, 3, 3, 1, 3, 0, 2, 1, 3, 3, 1, 1, 3, 1, 2, 3, 3, 3, 0, 2, 3, 2, 0, 1, 3, 3, 3, 2, 2, 2, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 3, 2, 0, 2, 3, 3, 3, 3, 2, 1, 1, 1, 2, 1, 3, 3, 3, 2, 2, 3, 3, 1, 2, 3, 0, 3, 2, 3, 3, 3, 3, 0, 2, 2, 3, 2, 2, 3, 3, 3, 3, 1, 3, 2, 3, 3, 3, 3, 3, 2, 2, 3, 1, 3, 0, 2, 1, 3, 3, 3, 3, 3, 3, 3, 3, 1, 3, 3, 3, 3, 2, 2, 2, 3, 1, 1, 3, 2, 2, 0, 3, 2, 1, 2, 1, 0, 3, 3, 3, 2, 2, 3, 2, 1, 2, 0, 0, 3, 3, 2, 3, 3, 2, 3, 3, 3, 3, 3, 2, 2, 2, 3, 3, 3, 3, 3, 1, 1, 3, 2, 2, 3, 1, 1, 0, 1, 3, 2, 3, 3, 2, 3, 3, 2, 3, 3, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 1, 2, 3, 3, 2, 2, 2, 2, 3, 3, 2, 0, 2, 1, 3, 3, 3, 3, 0, 3, 3, 3, 3, 2, 2, 3, 1, 3, 3, 3, 2, 3, 3, 3, 2, 3, 3, 3, 3, 2, 3, 2, 1, 3, 3, 3, 3, 2, 2, 0, 1, 2, 3, 2, 0, 3, 3, 3, 3, 3, 3, 1, 3, 3, 2, 3, 2, 2, 3, 3, 3, 3, 3, 2, 2, 3, 3, 2, 2, 2, 1, 3, 3, 3, 3, 1, 2, 3, 2, 3, 3, 2, 3, 2, 3, 3, 3, 2, 3, 1, 2, 3, 2, 1, 1, 3, 3, 2, 3, 3, 2, 3, 3, 0, 0, 1, 3, 3, 2, 3, 3, 3, 3, 1, 3, 3, 0, 3, 2, 3, 3, 1, 3, 3, 3, 3, 3, 3, 3, 0, 3, 3, 2};
 
         Assert.assertArrayEquals(expectedNumbers, numbers);
     }
@@ -42,6 +43,96 @@ public class FountainCodesTest {
         Assert.assertEquals(expectedNumbers, numbers);
     }
 
+    @Test
+    public void testPartitionAndJoin() {
+        byte[] message = URTest.makeMessage(1024, "Wolf");
+        int fragmentLen = FountainEncoder.findNominalFragmentLength(message.length, 10, 100);
+        List<byte[]> fragments = FountainEncoder.partitionMessage(message, fragmentLen);
+        List<String> fragmentsHex = fragments.stream().map(Utils::bytesToHex).collect(Collectors.toList());
+        String[] expectedFragmentsHex = new String[] {
+                "916ec65cf77cadf55cd7f9cda1a1030026ddd42e905b77adc36e4f2d3ccba44f7f04f2de44f42d84c374a0e149136f25b01852545961d55f7f7a8cde6d0e2ec43f3b2dcb644a2209e8c9e34af5c4747984a5e873c9cf5f965e25ee29039f",
+                "df8ca74f1c769fc07eb7ebaec46e0695aea6cbd60b3ec4bbff1b9ffe8a9e7240129377b9d3711ed38d412fbb4442256f1e6f595e0fc57fed451fb0a0101fb76b1fb1e1b88cfdfdaa946294a47de8fff173f021c0e6f65b05c0a494e50791",
+                "270a0050a73ae69b6725505a2ec8a5791457c9876dd34aadd192a53aa0dc66b556c0c215c7ceb8248b717c22951e65305b56a3706e3e86eb01c803bbf915d80edcd64d4d41977fa6f78dc07eecd072aae5bc8a852397e06034dba6a0b570",
+                "797c3a89b16673c94838d884923b8186ee2db5c98407cab15e13678d072b43e406ad49477c2e45e85e52ca82a94f6df7bbbe7afbed3a3a830029f29090f25217e48d1f42993a640a67916aa7480177354cc7440215ae41e4d02eae9a1912",
+                "33a6d4922a792c1b7244aa879fefdb4628dc8b0923568869a983b8c661ffab9b2ed2c149e38d41fba090b94155adbed32f8b18142ff0d7de4eeef2b04adf26f2456b46775c6c20b37602df7da179e2332feba8329bbb8d727a138b4ba7a5",
+                "03215eda2ef1e953d89383a382c11d3f2cad37a4ee59a91236a3e56dcf89f6ac81dd4159989c317bd649d9cbc617f73fe10033bd288c60977481a09b343d3f676070e67da757b86de27bfca74392bac2996f7822a7d8f71a489ec6180390",
+                "089ea80a8fcd6526413ec6c9a339115f111d78ef21d456660aa85f790910ffa2dc58d6a5b93705caef1091474938bd312427021ad1eeafbd19e0d916ddb111fabd8dcab5ad6a6ec3a9c6973809580cb2c164e26686b5b98cfb017a337968",
+                "c7daaa14ae5152a067277b1b3902677d979f8e39cc2aafb3bc06fcf69160a853e6869dcc09a11b5009f91e6b89e5b927ab1527a735660faa6012b420dd926d940d742be6a64fb01cdc0cff9faa323f02ba41436871a0eab851e7f5782d10",
+                "fbefde2a7e9ae9dc1e5c2c48f74f6c824ce9ef3c89f68800d44587bedc4ab417cfb3e7447d90e1e417e6e05d30e87239d3a5d1d45993d4461e60a0192831640aa32dedde185a371ded2ae15f8a93dba8809482ce49225daadfbb0fec629e",
+                "23880789bdf9ed73be57fa84d555134630e8d0f7df48349f29869a477c13ccca9cd555ac42ad7f568416c3d61959d0ed568b2b81c7771e9088ad7fd55fd4386bafbf5a528c30f107139249357368ffa980de2c76ddd9ce4191376be0e6b5",
+                "170010067e2e75ebe2d2904aeb1f89d5dc98cd4a6f2faaa8be6d03354c990fd895a97feb54668473e9d942bb99e196d897e8f1b01625cf48a7b78d249bb4985c065aa8cd1402ed2ba1b6f908f63dcd84b66425df00000000000000000000"
+        };
+
+        Assert.assertEquals(Arrays.asList(expectedFragmentsHex), fragmentsHex);
+
+        byte[] rejoinedMessage = FountainDecoder.joinFragments(fragments, message.length);
+        Assert.assertArrayEquals(message, rejoinedMessage);
+    }
+
+    @Test
+    public void testChooseDegree() {
+        byte[] message = URTest.makeMessage(1024, "Wolf");
+        int fragmentLen = FountainEncoder.findNominalFragmentLength(message.length, 10, 100);
+        List<byte[]> fragments = FountainEncoder.partitionMessage(message, fragmentLen);
+        List<Integer> degrees = IntStream.rangeClosed(1, 200).mapToObj( nonce -> {
+            RandomXoshiro256StarStar partRng = new RandomXoshiro256StarStar("Wolf-" + nonce);
+            return FountainUtils.chooseDegree(fragments.size(), partRng);
+        }).collect(Collectors.toList());
+        Integer[] expectedDegrees = new Integer[] {
+                11, 3, 6, 5, 2, 1, 2, 11, 1, 3, 9, 10, 10, 4, 2, 1, 1, 2, 1, 1, 5, 2, 4, 10, 3, 2, 1, 1, 3, 11, 2, 6, 2, 9, 9, 2, 6, 7, 2, 5, 2, 4, 3, 1, 6, 11, 2, 11, 3, 1, 6, 3, 1, 4, 5, 3, 6, 1, 1, 3, 1, 2, 2, 1, 4, 5, 1, 1, 9, 1, 1, 6, 4, 1, 5, 1, 2, 2, 3, 1, 1, 5, 2, 6, 1, 7, 11, 1, 8, 1, 5, 1, 1, 2, 2, 6, 4, 10, 1, 2, 5, 5, 5, 1, 1, 4, 1, 1, 1, 3, 5, 5, 5, 1, 4, 3, 3, 5, 1, 11, 3, 2, 8, 1, 2, 1, 1, 4, 5, 2, 1, 1, 1, 5, 6, 11, 10, 7, 4, 7, 1, 5, 3, 1, 1, 9, 1, 2, 5, 5, 2, 2, 3, 10, 1, 3, 2, 3, 3, 1, 1, 2, 1, 3, 2, 2, 1, 3, 8, 4, 1, 11, 6, 3, 1, 1, 1, 1, 1, 3, 1, 2, 1, 10, 1, 1, 8, 2, 7, 1, 2, 1, 9, 2, 10, 2, 1, 3, 4, 10
+        };
+        Assert.assertEquals(Arrays.asList(expectedDegrees), degrees);
+    }
+
+    @Test
+    public void testChooseFragment() {
+        byte[] message = URTest.makeMessage(1024, "Wolf");
+        CRC32 crc32 = new CRC32();
+        crc32.update(message);
+        long checksum = crc32.getValue();
+        int fragmentLen = FountainEncoder.findNominalFragmentLength(message.length, 10, 100);
+        List<byte[]> fragments = FountainEncoder.partitionMessage(message, fragmentLen);
+        List<List<Integer>> partIndexes = IntStream.rangeClosed(1, 30).mapToObj(nonce -> {
+            return FountainUtils.chooseFragments(nonce, fragments.size(), checksum).stream().sorted().collect(Collectors.toList());
+        }).collect(Collectors.toList());
+
+        Integer[][] expectedFragmentIndexes = new Integer[][] {
+                {0},
+                {1},
+                {2},
+                {3},
+                {4},
+                {5},
+                {6},
+                {7},
+                {8},
+                {9},
+                {10},
+                {9},
+                {2, 5, 6, 8, 9, 10},
+                {8},
+                {1, 5},
+                {1},
+                {0, 2, 4, 5, 8, 10},
+                {5},
+                {2},
+                {2},
+                {0, 1, 3, 4, 5, 7, 9, 10},
+                {0, 1, 2, 3, 5, 6, 8, 9, 10},
+                {0, 2, 4, 5, 7, 8, 9, 10},
+                {3, 5},
+                {4},
+                {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10},
+                {0, 1, 3, 4, 5, 6, 7, 9, 10},
+                {6},
+                {5, 6},
+                {7}
+        };
+
+        List<List<Integer>> expectedPartIndexes = Arrays.stream(expectedFragmentIndexes).map(Arrays::asList).collect(Collectors.toList());
+        Assert.assertEquals(expectedPartIndexes, partIndexes);
+    }
+
     @Test
     public void testXOR() {
         RandomXoshiro256StarStar rng = new RandomXoshiro256StarStar("Wolf");
@@ -73,17 +164,17 @@ public class FountainCodesTest {
                 "8507091901001a0167aa07581d73f021c0e6f65b05c0a494e50791270a0050a73ae69b6725505a2ec8a5",
                 "8508091901001a0167aa07581d791457c9876dd34aadd192a53aa0dc66b556c0c215c7ceb8248b717c22",
                 "8509091901001a0167aa07581d951e65305b56a3706e3e86eb01c803bbf915d80edcd64d4d0000000000",
-                "850a091901001a0167aa07581d4a1b58fa2733399e5ee04d87a2d1628186e3cd250f3ae0e25d7ae7a22b",
+                "850a091901001a0167aa07581d330f0f33a05eead4f331df229871bee733b50de71afd2e5a79f196de09",
-                "850b091901001a0167aa07581dd35acd70953cf29b542a94cbd75790c73cb4cb1056d56557bf0b70b936",
+                "850b091901001a0167aa07581d3b205ce5e52d8c24a52cffa34c564fa1af3fdffcd349dc4258ee4ee828",
-                "850c091901001a0167aa07581d8cde6d0e2ec43f3b2dcb644a2209e8c9e34af5c4747984a5e873c9cf5f",
+                "850c091901001a0167aa07581ddd7bf725ea6c16d531b5f03254783803048ca08b87148daacd1cd7a006",
                 "850d091901001a0167aa07581d760be7ad1c6187902bbc04f539b9ee5eb8ea6833222edea36031306c01",
-                "850e091901001a0167aa07581dcba44f7f04f2de44f42d84c374a0e149136f25b01852545961d55f7f7a",
+                "850e091901001a0167aa07581d5bf4031217d2c3254b088fa7553778b5003632f46e21db129416f65b55",
-                "850f091901001a0167aa07581d262518878e747c6eee337fbbd189f77b385efe55597b54cab65b7f8ac0",
+                "850f091901001a0167aa07581d73f021c0e6f65b05c0a494e50791270a0050a73ae69b6725505a2ec8a5",
-                "8510091901001a0167aa07581d2d4a0b8fb95226315ab796cd72f9c5f8ea2a5a84221f7e31318f71b7df",
+                "8510091901001a0167aa07581db8546ebfe2048541348910267331c643133f828afec9337c318f71b7df",
-                "8511091901001a0167aa07581d81bf178523c1e7daaacdc944d67183c8958ce8951768b4bb3cafb8dd51",
+                "8511091901001a0167aa07581d23dedeea74e3a0fb052befabefa13e2f80e4315c9dceed4c8630612e64",
-                "8512091901001a0167aa07581d8e1548d10a2cd18416a3428bcb1fe2e3cac640274e91df20bdbd4e4df9",
+                "8512091901001a0167aa07581dd01a8daee769ce34b6b35d3ca0005302724abddae405bdb419c0a6b208",
-                "8513091901001a0167aa07581d8a65ebbda606df01244a3dad6b76e258150e4c07021ce5c07ed30160c5",
+                "8513091901001a0167aa07581d3171c5dc365766eff25ae47c6f10e7de48cfb8474e050e5fe997a6dc24",
-                "8514091901001a0167aa07581d2b44620c8371a48f6935d2b525f19c7a4e98e3043a6a64d462870e98ce"
+                "8514091901001a0167aa07581de055c2433562184fa71b4be94f262e200f01c6f74c284b0dc6fae6673f"
         };
 
         Assert.assertEquals(Arrays.asList(expectedPartsHex), partsHex);