Encrypt Public Key Messages using symmetric encryption

CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- Examples (eth-pm): Encrypt Public Key Messages using symmetric encryption. 
+
 ### Changed
 - **Breaking**: Moved `startTime` and `endTime` for history queries to a `timeFilter` property as both or neither must be passed; passing only one parameter is not supported.
 

examples/eth-pm/README.md

@@ -7,6 +7,7 @@
 - Waku Light Push
 - Signature with Web3
 - Asymmetric Encryption
+- Symmetric Encryption
 
 A PoC implementation of [20/ETH-DM](https://rfc.vac.dev/spec/20/).
 

examples/eth-pm/src/App.tsx

@@ -3,7 +3,7 @@ import '@ethersproject/shims';
 import React, { useEffect, useState } from 'react';
 import './App.css';
 import { Waku } from 'js-waku';
-import { KeyPair } from './crypto';
+import { KeyPair, PublicKeyMessageEncryptionKey } from './crypto';
 import { Message } from './messaging/Messages';
 import 'fontsource-roboto';
 import { AppBar, IconButton, Toolbar, Typography } from '@material-ui/core';
@@ -108,10 +108,13 @@ function App() {
       setPublicKeys
     );
 
+    waku.relay.addDecryptionKey(PublicKeyMessageEncryptionKey);
     waku.relay.addObserver(observerPublicKeyMessage, [PublicKeyContentTopic]);
 
     return function cleanUp() {
       if (!waku) return;
+
+      waku.relay.deleteDecryptionKey(PublicKeyMessageEncryptionKey);
       waku.relay.deleteObserver(observerPublicKeyMessage, [
         PublicKeyContentTopic,
       ]);

examples/eth-pm/src/BroadcastPublicKey.tsx

@@ -1,6 +1,10 @@
 import { Button } from '@material-ui/core';
 import React, { useState } from 'react';
-import { createPublicKeyMessage, KeyPair } from './crypto';
+import {
+  createPublicKeyMessage,
+  KeyPair,
+  PublicKeyMessageEncryptionKey,
+} from './crypto';
 import { PublicKeyMessage } from './messaging/wire';
 import { WakuMessage, Waku } from 'js-waku';
 import { PublicKeyContentTopic } from './waku';
@@ -84,5 +88,7 @@ async function encodePublicKeyWakuMessage(
   publicKeyMessage: PublicKeyMessage
 ): Promise<WakuMessage> {
   const payload = publicKeyMessage.encode();
-  return await WakuMessage.fromBytes(payload, PublicKeyContentTopic);
+  return await WakuMessage.fromBytes(payload, PublicKeyContentTopic, {
+    symKey: PublicKeyMessageEncryptionKey,
+  });
 }

examples/eth-pm/src/crypto.ts

@@ -4,6 +4,12 @@ import { PublicKeyMessage } from './messaging/wire';
 import { hexToBuf, equalByteArrays, bufToHex } from 'js-waku/lib/utils';
 import { generatePrivateKey, getPublicKey } from 'js-waku';
 import * as sigUtil from 'eth-sig-util';
+import { PublicKeyContentTopic } from './waku';
+import { keccak256 } from 'ethers/lib/utils';
+
+export const PublicKeyMessageEncryptionKey = hexToBuf(
+  keccak256(Buffer.from(PublicKeyContentTopic, 'utf-8'))
+);
 
 export interface KeyPair {
   privateKey: Uint8Array;