Cooperative random

static/js/dom.js

@@ -0,0 +1,16 @@
+export function updatePlayerDom() {
+    let list = document.querySelector("#playerList");
+    list.replaceChildren();
+
+    let newDom = document.createElement("li");
+    newDom.textContent = ID;
+    list.appendChild(newDom);
+
+    for (let playerId of Object.keys(players)) {
+        let newDom = document.createElement("li");
+        if (playerId !== ID) {
+            newDom.textContent = playerId;
+            list.appendChild(newDom);
+        }
+    }
+}

static/js/index.js

@@ -1,21 +1,39 @@
+import { Player } from "./player.js";
+
 const ID = window.crypto.randomUUID();
 // Timeout to consider a player disconnected
 const TIMEOUT = 30_000;
 
 let players = {};
 
+const WAITING = 0;
+const PRE_GAME = 1;
+const PLAYING = 2;
+const POST_GAME = 3;
+
+let game_state = WAITING;
+
 document.addEventListener("DOMContentLoaded", () => {
     let socket = io();
 
     socket.on("connect", () => {
         console.log("Connected!");
-        socket.emit("message", { type: "ANNOUNCE", author: ID, name: "" });
-        players[ID] = { name: "", timeout: null };
+        socket.emit("message", {
+            type: "ANNOUNCE",
+            id: window.crypto.randomUUID(),
+            author: ID,
+            name: "",
+        });
+        // Create self
+        players[ID] = new Player(ID, name);
     });
 
     socket.on("message", (data) => {
         // Ignore any messages that originate from us.
-        if (data.author !== ID) {
+        if (data.author === ID) {
+            return;
+        }
+
         switch (data.type) {
             case "ANNOUNCE":
                 playerConnected(socket, data);
@@ -24,38 +42,158 @@ document.addEventListener("DOMContentLoaded", () => {
             case "KEEPALIVE":
                 keepAlive(data);
                 break;
-            }
+
+            case "SYNC":
+                sync(data);
+                break;
+
+            case "RANDOM":
+                cooperativeRandom(data);
+                break;
         }
     });
 
     // Emit keepalive messages to inform other players we are still here
     window.setInterval(() => {
-        socket.emit("message", { type: "KEEPALIVE", author: ID });
+        socket.emit("message", {
+            type: "KEEPALIVE",
+            id: window.crypto.randomUUID(),
+            author: ID,
+        });
     }, TIMEOUT / 5);
 });
 
+/**
+ * Process player connect packets: these inform that a new player has joined.
+ *
+ * @param socket Socket instance used to announce ourselves to new player
+ * @param data Packet received
+ */
 function playerConnected(socket, data) {
+    // Block players from joining mid-game
+    if (game_state !== WAITING) {
+        return;
+    }
+
     // When a new player is seen, all announce to ensure they know all players.
     if (players[data.author] === undefined) {
-        players[data.author] = { name: data.name, timeout: window.setTimeout(() => { delete players[data.author]; updatePlayerDom(); }, TIMEOUT) };
-        socket.emit("message", { type: "ANNOUNCE", author: ID, name: "" });
+        players[data.author] = new Player(data.author, data.name);
+        socket.emit("message", {
+            type: "ANNOUNCE",
+            id: window.crypto.randomUUID(),
+            author: ID,
+            name: "",
+        });
+        players[data.author].resetTimeout();
     } else {
     }
 
     updatePlayerDom();
 }
 
+/**
+ * Process keep-alive packets: these are packets that check players are still online.
+ *
+ * @param data Packet received
+ */
 function keepAlive(data) {
-    window.clearTimeout(players[data.author].timeout);
-    players[data.author].timeout = window.setTimeout(() => { delete players[data.author]; updatePlayerDom(); }, TIMEOUT);
+    players[data.author].resetTimeout();
 }
 
-function updatePlayerDom() {
-    let list = document.querySelector('#playerList');
-    list.replaceChildren();
-    for (let playerId of Object.keys(players)) {
-        let newDom = document.createElement('li');
-        newDom.textContent = playerId;
-        list.appendChild(newDom);
+/**
+ * Process sync packets: update player details like status and name.
+ *
+ * @param data Packet received
+ */
+function sync(data) {
+    players[data.author].name = data.name;
+    players[data.author].ready = data.ready;
+
+    if (allPlayersReady()) {
+        game_state = PRE_GAME;
+        // Decide turn order. "Master" begins a cooperative rng process.
+
+        //
+    }
+}
+
+function allPlayersReady() {
+    for (let player of Object.values(players)) {
+        if (!player.ready) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+// Track ongoing random sessions.
+const randomSessions = {};
+
+/**
+ * Process cooperative random protocol.
+ *
+ * @param socket Socket instance for communication
+ * @param data Packet received
+ */
+function cooperativeRandom(socket, data) {
+    // Step 0: extract relevant information from data
+    let session = randomSessions[data.session];
+    const stage = data.stage;
+
+    if (session === undefined) {
+        // Step 1: generate and encrypt our random value. 4 bytes = 32 bit integer
+        const noise = CryptoJS.libs.WordArray.random(4);
+        const key = CryptoJS.libs.WordArray.random(256);
+        const cipherText = CryptoJS.AES.encrypt(noise, key);
+
+        randomSessions[data.session] = {
+            range: data.range,
+            cipherTexts: {},
+            cipherKeys: {},
+            ourKey: key,
+            ourNoise: noise,
+            finalValue: -1,
+        };
+        session = randomSessions[data.session];
+
+        // Step 2: send our random value and wait for all responses
+        socket.emit("message", {
+            type: "RANDOM",
+            author: ID,
+            stage: "CIPHERTEXT",
+            range: data.range,
+            cipherText: cipherText,
+        });
+    }
+
+    if (stage === "CIPHERTEXT") {
+        session.cipherTexts[data.author] = data.cipherText;
+
+        if (Object.keys(session.cipherTexts).length === Object.keys(players).length) {
+            // Step 3: release our key once all players have sent a ciphertext
+            socket.emit("message", {
+                type: "RANDOM",
+                author: ID,
+                stage: "DECRYPT",
+                cipherKey: session.ourKey,
+            });
+        }
+    } else if (stage === "DECRYPT") {
+        session.cipherKeys[data.author] = data.cipherKey;
+
+        // Step 4: get final random value
+        if (Object.keys(session.cipherKeys).length === Object.keys(players).length) {
+            let total = 0;
+
+            for (let participant of Object.keys(session.cipherKeys)) {
+                total += CryptoJS.AES.decrypt(
+                    session.cipherTexts[participant],
+                    session.cipherKeys[participant]
+                );
+            }
+
+            session.finalValue = total % session.range;
+        }
     }
 }

static/js/player.js

@@ -0,0 +1,21 @@
+import { updatePlayerDom } from "./dom.js";
+
+export class Player {
+    constructor(id, name) {
+        this.name = name;
+        this.timeout = null;
+        this.id = id;
+        this.ready = false;
+    }
+
+    resetTimeout() {
+        if (this.timeout !== null) {
+            window.clearTimeout(players[data.author].timeout);
+        }
+
+        this.timeout = window.setTimeout(() => {
+            delete players[this.id];
+            updatePlayerDom();
+        }, TIMEOUT);
+    }
+}

templates/index.html

@@ -6,7 +6,8 @@
         <link href="{{ url_for('static', filename='css/style.css') }}" rel="stylesheet">
 
         <script src="https://cdn.socket.io/4.5.4/socket.io.min.js"></script>
-        <script src="{{ url_for('static', filename='js/index.js') }}"></script>
+        <script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/4.1.1/crypto-js.min.js"></script>
+        <script type="module" src="{{ url_for('static', filename='js/index.js') }}"></script>
     </head>
     <body>
 

whitepaper/demonstration/presentation.tex

@@ -0,0 +1,46 @@
+\documentclass{beamer}
+\usetheme{default}
+
+\setbeamertemplate{frametitle}[default][center]
+
+\title{"Risk" in an untrusted setting}
+\author{Jude Southworth}
+\begin{document}
+\begin{frame}[plain]
+    \maketitle
+\end{frame}
+\begin{frame}{Risk}
+	\begin{itemize}
+		\item \textit{Risk} is a popular strategy board game.
+		\item It is played on a single board, depicting a world map, partitioned into regions.
+		\item A player owns a region of the map by stationing troops within the region.
+		\item Players fight for regions by gambling some of their troops against the troops in the other player's region.
+	\end{itemize}
+\end{frame}
+\begin{frame}{Risk}
+	\begin{itemize}
+		\item \textit{Risk} has a variant called "fog of war".
+		\item In this variant, players cannot see the number of troops stationed within regions they don't control, or don't neighbour.
+		\item This variant is therefore only played online, in a \textbf{trusted setup}.
+	\end{itemize}
+\end{frame}
+\begin{frame}{Proposition}
+	\begin{itemize}
+		\item Play fog-of-war Risk in an untrusted setup.
+		\item In the untrusted setup, the same guarantees should be made as the trusted setup, but on a peer-to-peer network.
+	\end{itemize}
+\end{frame}
+\begin{frame}{Proposition}
+	\begin{itemize}
+		\item Zero-knowledge proofs. \begin{itemize}
+			\item 
+		\end{itemize}
+		\item Asymmetric encryption. \begin{itemize}
+			\item 
+		\end{itemize}
+		\item Hashing. \begin{itemize}
+			\item 
+		\end{itemize}
+	\end{itemize}
+\end{frame}
+\end{document}