From c5419630fc1959652d68fa14cedf7415739d8232 Mon Sep 17 00:00:00 2001
From: Franck Royer <franck@status.im>
Date: Fri, 2 Jul 2021 13:52:10 +1000
Subject: [PATCH] Define util function for hex<>buf conversions

---
 examples/eth-dm/src/InitWaku.tsx      | 12 ++++--------
 examples/eth-dm/src/crypto.ts         | 23 +++++++----------------
 examples/eth-dm/src/messaging/wire.ts |  5 -----
 examples/eth-dm/src/utils.ts          |  8 ++++++++
 4 files changed, 19 insertions(+), 29 deletions(-)
 create mode 100644 examples/eth-dm/src/utils.ts

diff --git a/examples/eth-dm/src/InitWaku.tsx b/examples/eth-dm/src/InitWaku.tsx
index da105ff848..4427d46c7d 100644
--- a/examples/eth-dm/src/InitWaku.tsx
+++ b/examples/eth-dm/src/InitWaku.tsx
@@ -1,13 +1,9 @@
 import { Dispatch, SetStateAction, useEffect } from 'react';
 import { Environment, getStatusFleetNodes, Waku, WakuMessage } from 'js-waku';
-import {
-  bytesToHexStr,
-  decode,
-  DirectMessage,
-  PublicKeyMessage,
-} from './messaging/wire';
+import { decode, DirectMessage, PublicKeyMessage } from './messaging/wire';
 import { decryptMessage, KeyPair, validatePublicKeyMessage } from './crypto';
 import { Message } from './messaging/Messages';
+import { byteArrayToHex } from './utils';
 
 export const PublicKeyContentTopic = '/eth-dm/1/public-key/proto';
 export const DirectMessageContentTopic = '/eth-dm/1/direct-message/json';
@@ -123,7 +119,7 @@ function handlePublicKeyMessage(
   if (!msg.payload) return;
   const publicKeyMsg = PublicKeyMessage.decode(msg.payload);
   if (!publicKeyMsg) return;
-  const ethDmPublicKey = bytesToHexStr(publicKeyMsg.ethDmPublicKey);
+  const ethDmPublicKey = byteArrayToHex(publicKeyMsg.ethDmPublicKey);
   if (ethDmPublicKey === myPublicKey) return;
 
   const res = validatePublicKeyMessage(publicKeyMsg);
@@ -131,7 +127,7 @@ function handlePublicKeyMessage(
 
   if (res) {
     setter((prevPks: Map<string, string>) => {
-      prevPks.set(bytesToHexStr(publicKeyMsg.ethAddress), ethDmPublicKey);
+      prevPks.set(byteArrayToHex(publicKeyMsg.ethAddress), ethDmPublicKey);
       return new Map(prevPks);
     });
   }
diff --git a/examples/eth-dm/src/crypto.ts b/examples/eth-dm/src/crypto.ts
index 0b72b88f69..1dd7c7b0f8 100644
--- a/examples/eth-dm/src/crypto.ts
+++ b/examples/eth-dm/src/crypto.ts
@@ -3,11 +3,8 @@ import '@ethersproject/shims';
 import * as EthCrypto from 'eth-crypto';
 import { ethers } from 'ethers';
 import { Signer } from '@ethersproject/abstract-signer';
-import {
-  bytesToHexStr,
-  DirectMessage,
-  PublicKeyMessage,
-} from './messaging/wire';
+import { DirectMessage, PublicKeyMessage } from './messaging/wire';
+import { byteArrayToHex, hexToBuf } from './utils';
 
 export interface KeyPair {
   privateKey: string;
@@ -33,21 +30,15 @@ export async function createPublicKeyMessage(
   ethDmPublicKey: string
 ): Promise<PublicKeyMessage> {
   const ethAddress = await web3Signer.getAddress();
-  const bytesEthDmPublicKey = Buffer.from(
-    ethDmPublicKey.replace(/0x/, ''),
-    'hex'
-  );
+  const bytesEthDmPublicKey = hexToBuf(ethDmPublicKey);
   const signature = await web3Signer.signMessage(
     formatPublicKeyForSignature(bytesEthDmPublicKey)
   );
 
-  const bytesEthAddress = Buffer.from(ethAddress.replace(/0x/, ''), 'hex');
-  const bytesSignature = Buffer.from(signature.replace(/0x/, ''), 'hex');
-
   return new PublicKeyMessage({
     ethDmPublicKey: bytesEthDmPublicKey,
-    ethAddress: bytesEthAddress,
-    signature: bytesSignature,
+    ethAddress: hexToBuf(ethAddress),
+    signature: hexToBuf(signature),
   });
 }
 
@@ -58,7 +49,7 @@ export function validatePublicKeyMessage(msg: PublicKeyMessage): boolean {
   const formattedMsg = formatPublicKeyForSignature(msg.ethDmPublicKey);
   try {
     const sigAddress = ethers.utils.verifyMessage(formattedMsg, msg.signature);
-    const sigAddressBytes = Buffer.from(sigAddress.replace(/0x/, ''), 'hex');
+    const sigAddressBytes = hexToBuf(sigAddress);
     // Compare the actual byte arrays instead of strings that may differ in casing or prefixing.
     const cmp = sigAddressBytes.compare(new Buffer(msg.ethAddress));
     console.log(
@@ -86,7 +77,7 @@ export function validatePublicKeyMessage(msg: PublicKeyMessage): boolean {
  */
 function formatPublicKeyForSignature(ethDmPublicKey: Uint8Array): string {
   return JSON.stringify({
-    ethDmPublicKey: bytesToHexStr(ethDmPublicKey),
+    ethDmPublicKey: byteArrayToHex(ethDmPublicKey),
   });
 }
 
diff --git a/examples/eth-dm/src/messaging/wire.ts b/examples/eth-dm/src/messaging/wire.ts
index d595ea978c..5a07803416 100644
--- a/examples/eth-dm/src/messaging/wire.ts
+++ b/examples/eth-dm/src/messaging/wire.ts
@@ -56,11 +56,6 @@ export class PublicKeyMessage {
   }
 }
 
-export function bytesToHexStr(bytes: Uint8Array): string {
-  const buf = new Buffer(bytes);
-  return buf.toString('hex');
-}
-
 /**
  * Direct Encrypted Message used for private communication over the Waku network.
  */
diff --git a/examples/eth-dm/src/utils.ts b/examples/eth-dm/src/utils.ts
new file mode 100644
index 0000000000..b1f36ac825
--- /dev/null
+++ b/examples/eth-dm/src/utils.ts
@@ -0,0 +1,8 @@
+export function byteArrayToHex(bytes: Uint8Array): string {
+  const buf = new Buffer(bytes);
+  return buf.toString('hex');
+}
+
+export function hexToBuf(str: string): Buffer {
+  return Buffer.from(str.replace(/0x/, ''), 'hex');
+}