encrypt and decrypt messages in browser

src/app.js

@@ -51,11 +51,11 @@ io.on('connection', async (socket) => {
     socket.on('disconnect', () => {
         console.log('User disconnected');
     });
-    socket.on('chat message', async (msg, room) => {
+    socket.on('chat message', async (msg, room, tag, iv, nonce) => {
         const roomid = room.substring(5);
         const members = await database.getRoomMembers(roomid);
         members.forEach(memberRoom => {
-            socket.to(memberRoom).emit('chat message', msg, roomid, session.publicKey);
+            socket.to(memberRoom).emit('chat message', msg, roomid, tag, iv, nonce);
         });
         console.log('message: ' + msg + ', sender: ' + session.id);
         console.log(session.publicKey);

src/controllers/main.js

@@ -6,7 +6,8 @@ const mainController = {
         let pubKeyHex = req.session.publicKey;
         let isLoggedIn = typeof pubKeyHex !== 'undefined';
         let pubKey = isLoggedIn ? stringutils.hexToPem(pubKeyHex).replaceAll('\n','') : null;
-        res.render('index', {isLoggedIn, pubKey});
+        let hex = `key-${pubKeyHex}`
+        res.render('index', {isLoggedIn, pubKey, hex});
     }
 };
 

src/public/chat.js

@@ -31,12 +31,16 @@ function init_ratchets(order, user_pubkey) {
 
 }
 
-socket.on('chat message', (msg, room) => {
+socket.on('chat message', (msg, room, tag_received, iv, nonce) => {
     console.log(`received: ${msg}`);
-    console.log(sharedsecret);
-    const item = document.createElement('li');
-    item.textContent = msg;
     const messages = document.getElementById(`messages-${room}`);
+    const associated_data = fromHexString(Array.from((document.getElementById('pubkey')).classList).find(className => className.startsWith('key-')).replace('key-', ''));
+    const pubkey = Array.from(messages.classList).find(className => className.startsWith('key-')).replace('key-', '');
+    const item = document.createElement('li');
+    let {plaintext, tag} = decrypt_message(msg, pubkey, fromHexString(iv), fromHexString(nonce), associated_data);
+    item.textContent = plaintext
+    console.log(tag);
+    console.log(tag_received);
     messages.appendChild(item);
     window.scrollTo(0, document.body.scrollHeight);
 });
@@ -69,12 +73,55 @@ export function create_listener(form, input) {
     form.addEventListener('submit', function(e) {
         e.preventDefault();
         if (input.value) {
-            socket.emit('chat message', input.value, form.id);
+            const pubkey = Array.from(form.classList).find(className => className.startsWith('key-')).replace('key-', '');
+            let {cipher, tag, iv, nonce} = encrypt_message(input.value, pubkey)
+            socket.emit('chat message', cipher, form.id, tag, iv, nonce);
             input.value = '';
         }
     });
 }
 
+function encrypt_message(message, user_pubkey) {
+    let encryption_key = sending_ratchets[user_pubkey].next();
+    let encoded_msg = (new TextEncoder()).encode(message);
+    let iv = generateRandomUint8Array();
+    let nonce = generateRandomUint8Array();
+    let associated_data = fromHexString(user_pubkey);
+    let {cipher, tag} = keccakAEAD.encrypt(encryption_key, encoded_msg, iv, associated_data, nonce);
+    console.log(iv)
+    console.log(nonce)
+    console.log(associated_data)
+    console.log(encryption_key)
+    console.log(encoded_msg)
+    console.log(cipher)
+    return {cipher: toHexString(cipher),
+            tag: toHexString(tag),
+            iv: toHexString(iv),
+            nonce: toHexString(nonce)
+            };
+}
+
+function decrypt_message(cipher, user_pubkey, iv, nonce, associated_data) {
+    let decryption_key = receiving_ratchets[user_pubkey].next();
+    let cipher_array = fromHexString(cipher);
+    let {plaintext, tag} = keccakAEAD.decrypt(decryption_key, cipher_array, iv, associated_data, nonce);
+    console.log(iv)
+    console.log(nonce)
+    console.log(associated_data)
+    console.log(decryption_key)
+    console.log(plaintext)
+    console.log(cipher_array)
+    return {plaintext: (new TextDecoder('utf-8')).decode(plaintext),
+            tag: toHexString(tag)
+            };
+}
+
+function generateRandomUint8Array(length = 16) {
+    const randomArray = new Uint8Array(length);
+    window.crypto.getRandomValues(randomArray);
+    return randomArray;
+}
+
 const fromHexString = (hexString) =>
     Uint8Array.from(hexString.match(/.{1,2}/g).map((byte) => parseInt(byte, 16)));
 

src/public/kdf.js

@@ -2,7 +2,7 @@ import { concatUint8Arrays } from './arrayutils.js';
 import { keccak } from './keccak.js';
 
 class keccakKDF {
-    constructor(encryptionKeyLength = 32, privateKeyLength = 32) {
+    constructor(encryptionKeyLength = 16, privateKeyLength = 32) {
         this.encryptionKeyLength = encryptionKeyLength;
         this.privateKeyLength = privateKeyLength;
     }
@@ -19,7 +19,7 @@ class keccakKDF {
         this.currentKey = initialKey;
         return this.kdf(salt);
     }
-    next(salt) {
+    next(salt=(new Uint8Array(0))) {
         if (!this.currentKey) throw new Error("KDF not initialized");
         return this.kdf(salt);
     }

src/public/rooms.js

@@ -18,6 +18,7 @@ function render_rooms(room_info) {
         roomDiv.classList.add(`key-${pubkey}`);
         const messagesUl = document.createElement('ul');
         messagesUl.id = `messages-${roomId}`;
+        messagesUl.classList.add(`key-${pubkey}`);
         const form = document.createElement('form');
         form.id = `form-${roomId}`;
         form.classList.add(`key-${pubkey}`);

src/views/index.pug

@@ -57,7 +57,7 @@ html(lang="en-US")
 
 
         .d-flex.mb-3
-          input#pubkey.form-control(type="text", value=pubKey, readonly, style="border-right: 0;")
+          input#pubkey.form-control(type="text", value=pubKey, class=hex, readonly, style="border-right: 0;")
           button#copyPubKey.btn.btn-outline-secondary(type="button") Copy
 
         #rooms