+ create user with public/private key

+ sign and verify votes and prevent unverified updates

.gitignore

@@ -0,0 +1,24 @@
+# Nuxt dev/build outputs
+.output
+.data
+.nuxt
+.nitro
+.cache
+dist
+
+# Node dependencies
+node_modules
+
+# Logs
+logs
+*.log
+
+# Misc
+.DS_Store
+.fleet
+.idea
+
+# Local env files
+.env
+.env.*
+!.env.example

README.md

@@ -1 +1,129 @@
-# P2P Poll App
+# 🗳️ P2P Verified Polling App
+
+A decentralized, real-time polling application built with **Nuxt 3**, **Yjs**, and **WebRTC**. This app allows users to create and participate in polls where every vote is cryptographically signed and verified peer-to-peer, ensuring data integrity without a central authority "owning" the results.
+
+---
+
+## 🌟 Key Features
+
+* **Serverless Real-time Sync:** Uses **Yjs** (CRDTs) and **WebRTC** to sync poll data directly between browsers. No database is required for live updates.
+* **Persistence with Nitro:** While the logic is P2P, the **Nuxt/Nitro** backend provides a "Snapshot" service to ensure polls persist even after all peers go offline.
+* **Cryptographic Integrity:** Every vote is signed using **RSA-PSS (Web Crypto API)**. Each user has a unique private key (stored locally via `.pem` files) to ensure votes cannot be forged or tampered with.
+* **Chained Verification:** Implements a "History-Signing" logic where each new vote signs the entire preceding state of the poll, creating a verifiable chain of trust.
+* **Privacy First:** Users identify via UUIDs and Public/Private key pairs rather than traditional accounts.
+
+---
+
+## ⚙️ How It Works
+
+### 1. Identity Creation
+When a new user is created, the system generates a unique **UUID (User ID)** and an **RSA Key Pair**. The user is prompted to save their **Private Key** as a `.pem` file, named after their User ID (e.g., `550e8400-e29b.pem`). This file acts as their "Passport"—it is never uploaded to the server and must be kept secure by the user.
+
+### 2. Authentication
+Upon returning to the app, users load their local `.pem` file. The application extracts the Private Key for signing and the UUID for identification. No passwords or central servers are involved in this local-first login process.
+
+### 3. Joining a Poll
+When a user joins a poll, the app fetches the latest binary snapshot from the server to populate a local **Y.Doc**. This ensures the user sees the current state immediately, even before connecting to other peers.
+
+### 4. The P2P Mesh
+The app establishes connections to other active voters via a WebRTC signaling server. Any changes made to the poll (adding options or voting) are broadcasted instantly to all peers using Conflict-free Replicated Data Types (CRDTs) to prevent sync conflicts.
+
+### 5. Casting a Signed Vote
+To ensure security, the voting process follows a strict cryptographic chain:
+* The app captures the current list of votes.
+* It appends the new vote data (User ID + Timestamp).
+* It signs the **entire array** (the previous history + the new vote) using the user's RSA private key.
+* The signed update is merged into the shared Yjs Map and broadcasted.
+
+### 6. Distributed Verification
+Whenever a peer receives a new update, they fetch the voter's **Public Key** from the API. They then verify that the signature matches the current state of the poll history. If a signature is invalid or the history has been tampered with, the vote is rejected by the peer's local state.
+
+---
+
+## 🛠️ Tech Stack
+
+* **Framework:** [Nuxt 3](https://nuxt.com/) (Vue 3 + TypeScript)
+* **Conflict-Free Replicated Data Types (CRDT):** [Yjs](https://yjs.dev/)
+* **P2P Transport:** `y-webrtc`
+* **Security:** Web Crypto API (SubtleCrypto)
+* **Backend/Storage:** Nitro (Nuxt's server engine) with filesystem storage drivers
+
+# AI Disclaimer
+
+This App was developed with the assistance of AI.
+
+# Nuxt Minimal Starter
+
+Look at the [Nuxt documentation](https://nuxt.com/docs/getting-started/introduction) to learn more.
+
+## Setup
+
+Make sure to install dependencies:
+
+```bash
+# npm
+npm install
+
+# pnpm
+pnpm install
+
+# yarn
+yarn install
+
+# bun
+bun install
+```
+
+## Development Server
+
+Start the development server on `http://localhost:3000`:
+
+```bash
+# npm
+npm run dev
+
+# pnpm
+pnpm dev
+
+# yarn
+yarn dev
+
+# bun
+bun run dev
+```
+
+## Production
+
+Build the application for production:
+
+```bash
+# npm
+npm run build
+
+# pnpm
+pnpm build
+
+# yarn
+yarn build
+
+# bun
+bun run build
+```
+
+Locally preview production build:
+
+```bash
+# npm
+npm run preview
+
+# pnpm
+pnpm preview
+
+# yarn
+yarn preview
+
+# bun
+bun run preview
+```
+
+Check out the [deployment documentation](https://nuxt.com/docs/getting-started/deployment) for more information.

app/app.vue

@@ -0,0 +1,175 @@
+<style>
+/* Basic styling to make it look clean */
+body {
+  font-family: system-ui, -apple-system, sans-serif;
+  background-color: #f4f4f9;
+  color: #333;
+  margin: 0;
+  display: flex;
+  justify-content: center;
+  padding: 2rem;
+}
+
+header {
+  margin-bottom: 2rem;
+  text-align: center;
+}
+
+h1 { margin: 0 0 0.5rem 0; }
+
+input {
+  flex-grow: 1;
+  padding: 0.75rem;
+  border: 1px solid #ccc;
+  border-radius: 6px;
+  font-size: 1rem;
+}
+
+button,
+.button {
+  background: #3b82f6;
+  color: white;
+  border: none;
+  padding: 0.75rem 1rem;
+  border-radius: 6px;
+  cursor: pointer;
+  font-weight: bold;
+  transition: background 0.2s;
+}
+
+button:hover,
+.button:hover { background: #2563eb; }
+
+.status {
+  font-size: 0.85rem;
+  color: #666;
+}
+.status .connected { color: #10b981; font-weight: bold; }
+
+.connectionFailed { color: #FF2525; font-weight: bold; }
+
+.poll-container {
+  background: white;
+  padding: 2rem;
+  border-radius: 12px;
+  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
+  width: 100%;
+  max-width: 500px;
+}
+
+.back-btn { 
+  margin-left: 1rem; 
+  padding: 0.2rem 0.5rem; 
+  font-size: 0.7rem; 
+  background: #64748b; 
+}
+
+/* Hide the actual file input */
+input[type="file"] {
+  display: none;
+}
+
+</style>
+<template>
+    <div class="poll-container">
+        <header>
+            <h1 @click="activePollId = null" style="cursor:pointer">P2P Polling App 🗳️</h1>
+            <div class="status">
+                <button v-if="activePollId" @click="activePollId = null" class="back-btn">← Back To List</button>
+                <span :class="{ 'connected': isConnected }">
+                    ● {{ isConnected ? 'Synced' : 'Waiting for other Peers...' }}
+                </span>
+                <span> | Peers online: {{ connectedPeers }}</span>
+                <h2 v-if="connectionAttempFailed" class="connectionFailed">⚠ Connection to Signaling Server Failed!</h2>
+                <div v-if="user===null" style="margin-top: 10px;">
+                    <button @click="createUser">Create New User</button>
+                    Or
+                    <label title="Select Key File">
+                        <span class="button">Login</span>
+                        <input 
+                            type="file"
+                            accept=".pem"
+                            @change="loadUser"
+                        />
+                    </label>
+                </div>
+            </div>
+        </header>
+
+        <main>
+            <PollList v-if="!activePollId" :userid="user?.userid" @select-poll="selectPoll" />
+            <Poll v-else :activePollId="activePollId" :userid="user?.userid" :poll-data="pollData" :addOption="addOption" :vote="vote"/>
+        </main>
+    </div>
+</template>
+
+<script setup lang="ts">
+    import { v4 as uuidv4 } from 'uuid';
+    const activePollId = ref<string | null>(null);
+    const user = shallowRef<UserData | null>(null);
+
+    const { pollData, isConnected, connectionAttempFailed, connectedPeers, addOption, vote } = usePoll(activePollId,user);
+
+    const selectPoll = (id: string) => {
+        activePollId.value = id;
+    };
+
+
+    const createUser = async () => {
+        try {
+            const keypair : CryptoKeyPair = await generateUserKeyPair();
+            console.log('keypair:', keypair);
+            const uuid = uuidv4();
+            user.value = {
+                userid: uuid,
+                private_key: keypair.privateKey,
+                public_key: keypair.publicKey,
+            };
+            const prvKeyString = await exportPrivateKey(keypair.privateKey);
+            await savePrivateKeyToFile(prvKeyString,uuid+".pem")
+
+            
+            const pubKeyString = await exportPublicKey(keypair.publicKey);
+            await $fetch(`/api/users/${uuid}`, {
+                method: 'POST',
+                body: { public_key: pubKeyString }
+            });
+        } catch (err) {
+            user.value = null
+            console.error("Failed to create new User!", err);
+        }
+    };
+    const loadUser = async (event: Event) => {
+        const target = event.target as HTMLInputElement;
+        const file = target.files?.[0];
+
+        if (file) {
+            try {
+                const content = await file.text();
+                console.log("File loaded: ");
+                if (file.name && content) {
+                    try {
+                        const uuid = file.name.replace(".pem", "");
+                        // Standardize the string for the importer
+                        const pkBase64 = content.replace(/-----BEGIN PRIVATE KEY-----|-----END PRIVATE KEY-----/g, "").replace(/\s+/g, "");
+
+                        const key = await stringToCryptoKey(pkBase64, "private");
+                        
+                        user.value = {
+                            userid: uuid,
+                            private_key: key,
+                            public_key: undefined, // Note: You might need to import a pub key too!
+                        };
+                        
+                        console.log("Login successful for:", uuid);
+                    } catch (err) {
+                        console.error("Crypto Import Error:", err);
+                        alert("The file content is not a valid Private Key.");
+                    }
+                }
+            } catch (e) {
+                console.error("Failed to read file", e);
+            }
+        }
+    };
+</script>

app/components/Poll.vue

@@ -0,0 +1,83 @@
+<style scoped>
+.poll-list {
+  list-style: none;
+  padding: 0;
+  margin: 0;
+}
+
+.poll-item {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  padding: 1rem;
+  background: #f8fafc;
+  border: 1px solid #e2e8f0;
+  border-radius: 8px;
+  margin-bottom: 0.5rem;
+}
+.poll-title { 
+  font-size: 1.1rem; 
+  color: #3b82f6; 
+  text-transform: uppercase; 
+  letter-spacing: 1px;
+}
+
+.add-option-form {
+  display: flex;
+  gap: 0.5rem;
+  margin-bottom: 2rem;
+}
+
+.option-name { font-weight: 500; }
+.vote-section { display: flex; align-items: center; gap: 1rem; }
+.vote-count { font-size: 0.9rem; color: #475569; }
+.vote-btn { padding: 0.4rem 0.8rem; background: #10b981; }
+.vote-btn:hover { background: #059669; }
+
+.vote-btn:disabled,
+.vote-btn[disabled] { background: #888888; }
+.vote-btn:disabled:hover,
+.vote-btn[disabled]:hover { background: #AAAAAA; }
+</style>
+
+<template>
+    <div>
+        <h2 class="poll-title">Poll: {{ activePollId }}</h2>
+        <p v-if="Object.keys(pollData).length==0">Note: Add at least one Option to save the Poll.</p>
+        <form @submit.prevent="handleAddNewOption" class="add-option-form" v-if="userid">
+            <input v-model="newOption" placeholder="Enter a new poll option..." required />
+            <button type="submit">Add Option</button>
+        </form>
+
+        <ul class="poll-list">
+            <li v-for="(votes, optionName) in pollData" :key="optionName" class="poll-item">
+                <span class="option-name">{{ optionName }}</span>
+                <div class="vote-section">
+                    <span class="vote-count">{{ votes.length }} {{ votes.length === 1 ? 'vote' : 'votes' }}</span>
+                    <button @click="vote(String(optionName))" class="vote-btn" :disabled="userid==undefined || voted(votes)">+1</button>
+                </div>
+            </li>
+        </ul>
+    </div>
+</template>
+
+<script setup lang="ts">
+    import type { PollProps, SignedData, VoteData } from '@/utils/types'
+    const props = defineProps<PollProps>()
+
+    const newOption = ref('');
+    const handleAddNewOption = () => {
+        props.addOption(newOption.value);
+        newOption.value = '';
+    };
+
+
+    const voted = (votes: SignedData<VoteData>[]) => {
+        for(let vote of votes){
+            if(vote.data.userid == props.userid){
+                return true;
+            }
+        }
+        return false;
+    }
+</script>

app/components/PollList.vue

@@ -0,0 +1,64 @@
+<style scoped>
+    .poll-list { margin-top: 1rem; }
+    .empty-state { text-align: center; color: #94a3b8; font-style: italic; }
+    .create-poll { display: flex; gap: 0.5rem; margin-bottom: 1.5rem; }
+    .poll-links { list-style: none; padding: 0; }
+    .poll-link-btn {
+        width: 100%;
+        text-align: left;
+        background: #f1f5f9;
+        color: #1e293b;
+        margin-bottom: 0.5rem;
+        display: flex;
+        justify-content: space-between;
+    }
+    .poll-link-btn:hover { background: #e2e8f0; }
+</style>
+
+<template>
+    <div class="poll-list">
+        <h3>Available Polls</h3>
+
+        <ul v-if="polls && polls.length > 0" class="poll-links">
+            <li v-for="id in polls" :key="id">
+                <button class="poll-link-btn" @click="$emit('select-poll', id)">
+                    {{ id }} <span>→</span>
+                </button>
+            </li>
+        </ul>
+        <p v-else class="empty-state">No polls found. Create the first one!</p>
+        <div class="create-poll" v-if="userid !== undefined">
+            <input 
+                v-model="newPollId" 
+                placeholder="Enter new poll name..." 
+                @keyup.enter="createPoll"
+            />
+            <button @click="createPoll">Create & Join</button>
+        </div>
+    </div>
+</template>
+
+<script setup lang="ts">
+    import type { PollListProps } from '@/utils/types'
+    const props = defineProps<PollListProps>()
+    const newPollId = ref('');
+    const polls = ref<string[]>([]);
+
+    // Fetch existing polls on mount
+    const fetchPolls = async () => {
+        const data = await $fetch<{ polls: string[] }>('/api/polls');
+        polls.value = data.polls;
+    };
+
+    const createPoll = () => {
+        const id = newPollId.value.trim().toLowerCase().replace(/\s+/g, '-');
+        if (id) {
+            // In a real app, you might want to POST to create it first, 
+            // but here we just navigate to it and let usePoll handle the save.
+            emit('select-poll', id);
+        }
+    };
+
+    const emit = defineEmits(['select-poll']);
+    onMounted(fetchPolls);
+</script>

app/composables/usePoll.ts

@@ -0,0 +1,131 @@
+// composables/usePoll.ts
+import { ref, watch, onUnmounted } from 'vue';
+import * as Y from 'yjs';
+
+export const usePoll = (pollId: Ref<string | null>, user: Ref<UserData | null>) => {
+    const pollData = ref<PollData>({});
+    const isConnected = ref(false);
+    const connectionAttempFailed = ref(false);
+    const connectedPeers = ref(1);
+
+    let ydoc: Y.Doc | null = null;
+    let provider: any = null;
+    let yMap: Y.Map<SignedData<VoteData>[]> | null = null;
+
+    const cleanup = () => {
+    if (provider) provider.disconnect();
+        if (ydoc) ydoc.destroy();
+        isConnected.value = false;
+        pollData.value = {};
+    };
+
+    const initPoll = async (id: string) => {
+        cleanup(); // Clear previous session
+
+        ydoc = new Y.Doc();
+
+        // 1. Fetch Snapshot from Nuxt API
+        try {
+            const response = await $fetch<{ update: number[] | null }>(`/api/polls/${id}`).catch((e) => {
+                console.error("Failed to get poll: " + id,e)
+            });
+            //trust the server without verification.
+            if (response?.update) {
+                Y.applyUpdate(ydoc, new Uint8Array(response.update));
+            }
+        } catch (err) {
+            console.error('Persistence fetch failed', err);
+        }
+
+        yMap = ydoc.getMap<SignedData<VoteData>[]>('shared-poll');
+
+        // 2. Local State Sync
+        yMap.observe(async () => {
+            await performUpdateAndVerify();
+            saveStateToServer(id);
+        });
+        await performUpdateAndVerify();
+
+        // 3. P2P Connection
+        const { WebrtcProvider } = await import('y-webrtc');
+        provider = new WebrtcProvider(`nuxt-p2p-${id}`, ydoc, {
+            signaling: ["ws://localhost:4444", "ws://lynxpi.ddns.net:4444"]
+        });
+
+        provider.on('synced', (arg: {synced: boolean}) => {
+            isConnected.value = arg.synced;
+            console.log('Connection synced:', arg.synced) // "connected" or "disconnected"
+        });
+        provider.on('status', (event: { connected: boolean }) => {
+            console.log('Connection status:', event.connected) // "connected" or "disconnected"
+        })
+        provider.on('peers', (data: any) => {
+            connectedPeers.value = data.webrtcPeers.length + 1
+        });
+    };
+
+    const saveStateToServer = async (id: string) => {
+        if (!ydoc) return;
+        const stateUpdate = Y.encodeStateAsUpdate(ydoc);
+        await $fetch(`/api/polls/${id}`, {
+            method: 'POST',
+            body: { update: Array.from(stateUpdate) }
+        }).catch((e) => {
+            console.error("Failed to update poll",e)
+        });
+    };
+
+    // Watch for ID changes (e.g., user clicks a link or goes back)
+    watch(pollId, (newId) => {
+        if (newId && import.meta.client) {
+            initPoll(newId);
+        } else {
+            cleanup();
+        }
+    }, { immediate: true });
+
+    onUnmounted(cleanup);
+
+    const addOption = (optionName: string) => {
+        if (yMap && !yMap.has(optionName)) yMap.set(optionName, []);
+    };
+
+    const performUpdateAndVerify = async () => {
+        const pollDataUpdate = yMap!.toJSON();
+        console.log("Poll Data Update: ", pollDataUpdate)
+        for(var option in pollDataUpdate){
+            console.log("verifying votes for option: " + option);
+            const votes = pollDataUpdate[option] || [];
+            const verified = await verifyAllVotesForOption(votes);
+            if(!verified){
+                console.error("Failed to verify option: "+option)
+                return;
+            }
+        }
+        console.log("All options verified! :)")
+        pollData.value = pollDataUpdate
+    }
+
+    const vote = async (optionName: string) => {
+        const currentUser = user.value;
+        if (currentUser != undefined && yMap?.has(optionName)) {
+            const voteData = [...(yMap.get(optionName) || [])];
+            if(voteData != undefined && currentUser.private_key){
+                var unsignedVoteData : VoteData = {
+                    userid: currentUser.userid,
+                    timestamp: new Date().toISOString()
+                }
+                var newVote : SignedData<VoteData> = {
+                    data: unsignedVoteData,
+                    signature: "",
+                }
+                voteData?.push(newVote)
+                const signature = await signVote(voteData,currentUser.private_key);
+                newVote.signature=signature
+                yMap?.set(optionName, voteData);
+            }
+        }
+    };
+
+    return { pollData, isConnected, connectionAttempFailed, connectedPeers, addOption, vote };
+};

app/composables/user.ts

@@ -0,0 +1,2 @@
+export const user = (user: Ref<UserData | null>) => {
+}

app/utils/crypto.ts

@@ -0,0 +1,187 @@
+// utils/crypto.ts
+export const generateUserKeyPair = async () => {
+  return await window.crypto.subtle.generateKey(
+    {
+      name: "RSASSA-PKCS1-v1_5",
+      modulusLength: 2048,
+      publicExponent: new Uint8Array([1, 0, 1]), // 65537
+      hash: "SHA-256",
+    },
+    true, // extractable
+    ["sign", "verify"]
+  );
+};
+
+export const signVote = async (data: any, privateKey: CryptoKey) => {
+  const encoder = new TextEncoder();
+  const encodedData = encoder.encode(JSON.stringify(data));
+
+  const signature = await window.crypto.subtle.sign(
+    "RSASSA-PKCS1-v1_5",
+    privateKey,
+    encodedData
+  );
+
+  // Convert to Base64 or Hex to store in Yjs easily
+  return btoa(String.fromCharCode(...new Uint8Array(signature)));
+};
+
+export const verifyVote = async (data: any, signatureStr: string, publicKey: CryptoKey) => {
+  const encoder = new TextEncoder();
+  const encodedData = encoder.encode(JSON.stringify(data));
+  
+  // Convert Base64 back to Uint8Array
+  const signature = Uint8Array.from(atob(signatureStr), c => c.charCodeAt(0));
+
+  return await window.crypto.subtle.verify(
+    "RSASSA-PKCS1-v1_5",
+    publicKey,
+    signature,
+    encodedData
+  );
+};
+
+/**
+ * Verifies a specific vote within an array of votes by 
+ * reconstructing the "signed state" at that point in time.
+ */
+export const verifyChainedVote = async (
+    voteData: SignedData<VoteData>[], 
+    index: number
+) => {
+    const voteToVerify = voteData[index];
+    console.log("Verifying vote: " + voteToVerify)
+    if(voteToVerify) {
+        // 1. Reconstruct the exact data state the user signed
+        // We need the array exactly as it was when they pushed their vote
+        const historicalState = voteData.slice(0, index + 1).map((v, i) => {
+            if (i === index) {
+                // For the current vote, the signature must be empty string
+                // because it wasn't signed yet when passed to signVote
+                return { ...v, signature: "" };
+            }
+            return v;
+        });
+
+        try {
+            // 2. Fetch public key
+            const response = await $fetch<{ public_key: string }>(`/api/users/${voteToVerify.data.userid}`);
+            console.log("Got key: ",response)
+            const pubKey = await stringToCryptoKey(response.public_key, 'public');
+
+            console.log("Using pubKey to verify Vote.")
+            // 3. Verify: Does this historicalState match the signature?
+            return await verifyVote(historicalState, voteToVerify.signature, pubKey);
+        } catch (err) {
+            console.error("Verification failed")
+            console.error(err);
+            return false;
+        }
+    }
+    console.error("Vote is undefined or null");
+    return false;
+};
+
+export const verifyAllVotesForOption = async (votes: SignedData<VoteData>[]) => {
+    console.log("verifying votes for option ",votes);
+    for (let i = votes.length-1; i >= 0 ; i--) {
+        const isValid = await verifyChainedVote(votes, i);
+        if(!isValid){
+            console.error("Error! Invalid Vote at: " + i,votes)
+            return false;
+        }
+    }
+    return true;
+};
+
+// Helper to convert ArrayBuffer to Base64 string
+const bufferToBase64 = (buf: ArrayBuffer) => 
+  window.btoa(String.fromCharCode(...new Uint8Array(buf)));
+
+export const exportPublicKey = async (key: CryptoKey) => {
+  // Export Public Key
+  const exportedPublic = await window.crypto.subtle.exportKey("spki", key);
+  const publicKeyString = bufferToBase64(exportedPublic);
+
+  return publicKeyString;
+};
+export const exportPrivateKey = async (key: CryptoKey) => {
+  // Export Private Key
+  const exportedPrivate = await window.crypto.subtle.exportKey("pkcs8", key);
+  const privateKeyString = bufferToBase64(exportedPrivate);
+
+  return privateKeyString;
+};
+
+/**
+ * Converts a Base64 string back into a usable CryptoKey object
+ * @param keyStr The Base64 string (without PEM headers)
+ * @param type 'public' or 'private'
+ */
+export const stringToCryptoKey = async (keyStr: string, type: 'public' | 'private'): Promise<CryptoKey> => {
+  // 1. Convert Base64 string to a Uint8Array (binary)
+  const binaryString = window.atob(keyStr);
+  const bytes = new Uint8Array(binaryString.length);
+  for (let i = 0; i < binaryString.length; i++) {
+    bytes[i] = binaryString.charCodeAt(i);
+  }
+
+  // 2. Identify the format based on the key type
+  // Public keys usually use 'spki', Private keys use 'pkcs8'
+  const format = type === 'public' ? 'spki' : 'pkcs8';
+  const usages: KeyUsage[] = type === 'public' ? ['verify'] : ['sign'];
+
+  // 3. Import the key
+  return await window.crypto.subtle.importKey(
+    format,
+    bytes.buffer,
+    {
+      name: "RSASSA-PKCS1-v1_5",
+      hash: "SHA-256",
+    },
+    true, // extractable (set to false if you want to lock it in memory)
+    usages
+  );
+};
+
+export const savePrivateKeyToFile = (privateKeyStr: string, filename: string) => {
+  // Optional: Wrap in PEM headers for standard formatting
+  const pemHeader = "-----BEGIN PRIVATE KEY-----\n";
+  const pemFooter = "\n-----END PRIVATE KEY-----";
+  const fileContent = pemHeader + privateKeyStr + pemFooter;
+
+  const blob = new Blob([fileContent], { type: "text/plain" });
+  const url = URL.createObjectURL(blob);
+  
+  const link = document.createElement("a");
+  link.href = url;
+  link.download = filename;
+  
+  document.body.appendChild(link);
+  link.click();
+  
+  // Cleanup
+  document.body.removeChild(link);
+  URL.revokeObjectURL(url);
+};
+
+export const loadPrivateKeyFromFile = async (file: File): Promise<string> => {
+  return new Promise((resolve, reject) => {
+    const reader = new FileReader();
+
+    reader.onload = (e) => {
+      const content = e.target?.result as string;
+      
+      // Clean up the string by removing PEM headers and newlines
+      const cleanKey = content
+        .replace("-----BEGIN PRIVATE KEY-----", "")
+        .replace("-----END PRIVATE KEY-----", "")
+        .replace(/\s+/g, ""); // Removes all whitespace/newlines
+        
+      resolve(cleanKey);
+    };
+
+    reader.onerror = () => reject("Error reading file");
+    reader.readAsText(file);
+  });
+};

app/utils/types.ts

@@ -0,0 +1,36 @@
+export interface PollProps {
+    userid: string | undefined,
+    activePollId: string,
+    pollData: PollData,
+    addOption: (name: string) => void,
+    vote: (optionName: string) => void
+}
+
+export interface PollListProps {
+    userid: string | undefined,
+}
+
+export interface PollData extends Record<string, SignedData<VoteData>[]> {
+}
+
+export interface SignedData<T> {
+    data: T,
+    signature: string
+}
+
+export interface VoteData {
+    userid: string,
+    timestamp: string
+}
+
+export interface OptionData {
+    userid: string,
+    timestamp: string,
+    optionName: string
+}
+
+export interface UserData {
+    userid: string,
+    private_key: CryptoKey | undefined,
+    public_key: CryptoKey | undefined
+}

nuxt.config.ts

@@ -0,0 +1,23 @@
+// https://nuxt.com/docs/api/configuration/nuxt-config
+export default defineNuxtConfig({
+  compatibilityDate: '2025-07-15',
+  devtools: { enabled: true },
+  vite: {
+    optimizeDeps: {
+      include: ['yjs', 'y-webrtc']
+    }
+  },
+  // ... existing config
+  nitro: {
+    storage: {
+      polls: {
+        driver: 'fs',
+        base: './.data/polls'
+      },
+      users: {
+        driver: 'fs',
+        base: './.data/users'
+      }
+    }
+  }
+})

package.json

@@ -0,0 +1,20 @@
+{
+  "name": "p2p-poll",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "build": "nuxt build",
+    "dev": "PORT=4444 npx y-webrtc & nuxt dev",
+    "generate": "nuxt generate",
+    "preview": "nuxt preview",
+    "postinstall": "nuxt prepare"
+  },
+  "dependencies": {
+    "nuxt": "^4.1.3",
+    "uuid": "^13.0.0",
+    "vue": "^3.5.30",
+    "vue-router": "^5.0.3",
+    "y-webrtc": "^10.3.0",
+    "yjs": "^13.6.30"
+  }
+}

public/robots.txt

@@ -0,0 +1,2 @@
+User-Agent: *
+Disallow:

server/api/polls/[id].ts

@@ -0,0 +1,68 @@
+import * as Y from 'yjs';
+// server/api/polls/[id].ts
+export default defineEventHandler(async (event) => {
+    const method = event.node.req.method;
+    const pollId = getRouterParam(event, 'id');
+
+    // We use Nitro's built-in storage. 
+    // 'polls' is the storage namespace.
+    const storage = useStorage('polls'); 
+
+    if (!pollId) {
+        throw createError({ statusCode: 400, statusMessage: 'Poll ID required' });
+    }
+
+    // GET: Fetch the saved Yjs document state
+    if (method === 'GET') {
+        const data = await storage.getItem(`poll:${pollId}`);
+        // Return the array of numbers (or null if it doesn't exist yet)
+        return { update: data || null };
+    }
+
+    // POST: Save a new Yjs document state
+    if (method === 'POST') {
+        const body = await readBody(event);
+
+        if (body.update && Array.isArray(body.update)) {
+            // create a temp Y.Doc to encode the Data
+            const tempDoc = new Y.Doc();
+            Y.applyUpdate(tempDoc, new Uint8Array(body.update));
+            const yMap = tempDoc.getMap('shared-poll');
+            const pollData = yMap.toJSON();
+
+            // verify pollData
+            for(var option in pollData){
+                const votes = pollData[option] || [];
+                var pubKeys: CryptoKey[] = [];
+
+                const verifyAllVotesForOption = async (votes: SignedData<VoteData>[]) => {
+                    console.log("verifying votes for option " + option,votes);
+                    // check last votes first. if there is something wrong, its likely in the last vote.
+                    for (let i = votes.length-1; i >= 0 ; i--) {
+                        const userStorage = useStorage('users'); 
+                        const votePubKeyString = await userStorage.getItem(`user:${votes[i]?.data.userid}`);
+                        //console.log("Using public key: "+votePubKeyString)
+                        const votePubKey = await stringToCryptoKey(String(votePubKeyString),'public')
+                        const isValid = await verifyChainedVote(votes, i,votePubKey);
+                        if(!isValid){
+                            console.error("Error! Invalid Vote at: " + i,votes)
+                            return false;
+                        }
+                    }
+                    return true;
+                };
+                const verified = await verifyAllVotesForOption(votes);
+                if(!verified){
+                    console.error("Failed to verify option: "+option)
+                    throw createError({ statusCode: 400, statusMessage: 'PollData contains unverifyable content!' });
+                }
+            }
+
+            // Save the binary update (sent as an array of numbers) to storage
+            await storage.setItem(`poll:${pollId}`, body.update);
+            return { success: true };
+        }
+
+        throw createError({ statusCode: 400, statusMessage: 'Invalid update payload' });
+    }
+});

server/api/polls/index.get.ts

@@ -0,0 +1,15 @@
+// server/api/polls/index.get.ts
+export default defineEventHandler(async () => {
+    const storage = useStorage('polls');
+    
+    // Get all keys in the 'polls' namespace
+    const allKeys = await storage.getKeys();
+    
+    // Filter for our specific poll prefix and strip it for the UI
+    // poll:my-id -> my-id
+    const polls = allKeys
+        .filter(key => key.startsWith('poll:'))
+        .map(key => key.replace('poll:', ''));
+
+    return { polls };
+});

server/api/users/[id].ts

@@ -0,0 +1,41 @@
+// server/api/users/[id].ts
+export default defineEventHandler(async (event) => {
+    const method = event.node.req.method;
+    const userId = getRouterParam(event, 'id');
+
+    // We use Nitro's built-in storage. 
+    // 'polls' is the storage namespace.
+    const storage = useStorage('users'); 
+
+    if (!userId) {
+        throw createError({ statusCode: 400, statusMessage: 'User ID required' });
+    }
+
+    // GET: Fetch the saved Yjs document state
+    if (method === 'GET') {
+        const data = await storage.getItem(`user:${userId}`);
+        // Return the array of numbers (or null if it doesn't exist yet)
+        return { public_key: data };
+    }
+
+    // POST: Save a new Yjs document state
+    if (method === 'POST') {
+        const body = await readBody(event);
+
+        if (body.public_key) {
+            const data = await storage.getItem(`user:${userId}`);
+
+            if (data == undefined || data == null) {
+                // Save the binary update (sent as an array of numbers) to storage
+                await storage.setItem(`user:${userId}`, body.public_key);
+                console.log("New User created: " + userId)
+                console.log("Public Key: " + body.public_key);
+                return { success: true };
+            }
+
+            throw createError({ statusCode: 400, statusMessage: 'User already exists.' });
+        }
+
+        throw createError({ statusCode: 400, statusMessage: 'Invalid update payload' });
+    }
+});

server/utils/crypto.ts

@@ -0,0 +1,86 @@
+import { SignedData, VoteData } from "./types";
+/**
+ * Gets the WebCrypto API regardless of environment (Node vs Browser)
+ */
+const getCrypto = () => {
+  return (globalThis as any).crypto;
+};
+
+export const verifyVote = async (data: any, signatureStr: string, publicKey: CryptoKey) => {
+  const encoder = new TextEncoder();
+  const encodedData = encoder.encode(JSON.stringify(data));
+  
+  // Convert Base64 back to Uint8Array
+  const signature = Uint8Array.from(atob(signatureStr), c => c.charCodeAt(0));
+
+  return await getCrypto().subtle.verify(
+    "RSASSA-PKCS1-v1_5",
+    publicKey,
+    signature,
+    encodedData
+  );
+};
+
+/**
+ * Verifies a specific vote within an array of votes by 
+ * reconstructing the "signed state" at that point in time.
+ */
+export const verifyChainedVote = async (
+    voteData: SignedData<VoteData>[], 
+    index: number,
+    pubKey: CryptoKey
+) => {
+    const voteToVerify = voteData[index];
+    console.log("Verifying vote: " + voteToVerify)
+    if(voteToVerify) {
+        // 1. Reconstruct the exact data state the user signed
+        // We need the array exactly as it was when they pushed their vote
+        const historicalState = voteData.slice(0, index + 1).map((v, i) => {
+            if (i === index) {
+                // For the current vote, the signature must be empty string
+                // because it wasn't signed yet when passed to signVote
+                return { ...v, signature: "" };
+            }
+            return v;
+        });
+
+        try {
+            // 3. Verify: Does this historicalState match the signature?
+            return await verifyVote(historicalState, voteToVerify.signature, pubKey);
+        } catch (err) {
+            console.error("Verification failed")
+            console.error(err);
+            return false;
+        }
+    }
+    console.error("Vote is undefined or null");
+    return false;
+};
+
+
+/**
+ * Converts a Base64 string back into a usable CryptoKey object
+ * @param keyStr The Base64 string (without PEM headers)
+ * @param type 'public' or 'private'
+ */
+export const stringToCryptoKey = async (keyStr: string, type: 'public' | 'private'): Promise<CryptoKey> => {
+  // 1. Convert Base64 string to a Uint8Array (binary)
+  const bytes = Buffer.from(keyStr, 'base64');
+
+  // 2. Identify the format based on the key type
+  // Public keys usually use 'spki', Private keys use 'pkcs8'
+  const format = type === 'public' ? 'spki' : 'pkcs8';
+  const usages: KeyUsage[] = type === 'public' ? ['verify'] : ['sign'];
+
+  // 3. Import the key
+  return await getCrypto().subtle.importKey(
+    format,
+    bytes,
+    {
+      name: "RSASSA-PKCS1-v1_5",
+      hash: "SHA-256",
+    },
+    true, // extractable (set to false if you want to lock it in memory)
+    usages
+  );
+};

server/utils/types.ts

@@ -0,0 +1,36 @@
+export interface PollProps {
+    userid: string | undefined,
+    activePollId: string,
+    pollData: PollData,
+    addOption: (name: string) => void,
+    vote: (optionName: string) => void
+}
+
+export interface PollListProps {
+    userid: string | undefined,
+}
+
+export interface PollData extends Record<string, SignedData<VoteData>[]> {
+}
+
+export interface SignedData<T> {
+    data: T,
+    signature: string
+}
+
+export interface VoteData {
+    userid: string,
+    timestamp: string
+}
+
+export interface OptionData {
+    userid: string,
+    timestamp: string,
+    optionName: string
+}
+
+export interface UserData {
+    userid: string,
+    private_key: CryptoKey | undefined,
+    public_key: CryptoKey | undefined
+}

tsconfig.json

@@ -0,0 +1,18 @@
+{
+  // https://nuxt.com/docs/guide/concepts/typescript
+  "files": [],
+  "references": [
+    {
+      "path": "./.nuxt/tsconfig.app.json"
+    },
+    {
+      "path": "./.nuxt/tsconfig.server.json"
+    },
+    {
+      "path": "./.nuxt/tsconfig.shared.json"
+    },
+    {
+      "path": "./.nuxt/tsconfig.node.json"
+    }
+  ]
+}