Implement and test symmetric encryption in the browser

src/lib/waku_message/symmetric/browser.ts

@@ -18,11 +18,8 @@ if (subtle === undefined) {
   throw new Error('Failed to load Subtle CryptoAPI');
 }
 
-/**
- * Proceed with symmetric encryption of `clearText` value.
- */
-async function encrypt(
-  iv: Buffer,
+export async function encrypt(
+  iv: Buffer | Uint8Array,
   key: Buffer,
   clearText: Buffer
 ): Promise<Buffer> {
@@ -34,10 +31,7 @@ async function encrypt(
     .then(Buffer.from);
 }
 
-/**
- * Proceed with symmetric decryption of `cipherText` value.
- */
-async function decrypt(
+export async function decrypt(
   iv: Buffer,
   key: Buffer,
   cipherText: Buffer
@@ -45,21 +39,17 @@ async function decrypt(
   return subtle
     .importKey('raw', key, Algorithm, false, ['decrypt'])
     .then((cryptoKey) =>
-      subtle.encrypt({ iv, ...Algorithm }, cryptoKey, cipherText)
+      subtle.decrypt({ iv, ...Algorithm }, cryptoKey, cipherText)
     )
     .then(Buffer.from);
 }
 
-/**
- * Generate a new private key for Symmetric encryption purposes.
- */
-function generateKeyForSymmetricEnc(): Buffer {
+export function generateKeyForSymmetricEnc(): Buffer {
   return crypto.getRandomValues(Buffer.alloc(SymmetricKeySize));
 }
 
-/**
- * Generate an Initialisation Vector (iv) for for Symmetric encryption purposes.
- */
-function generateIv(): Buffer {
-  return crypto.getRandomValues(Buffer.alloc(IvSize));
+export function generateIv(): Uint8Array {
+  const iv = new Uint8Array(IvSize);
+  crypto.getRandomValues(iv);
+  return iv;
 }

src/lib/waku_message/symmetric/index.ts

@@ -3,17 +3,33 @@ export const IvSize = 12;
 export const TagSize = 16;
 
 export interface Symmetric {
-  encrypt: (iv: Buffer, key: Buffer, clearText: Buffer) => Buffer;
-  decrypt: (iv: Buffer, tag: Buffer, key: Buffer, cipherText: Buffer) => Buffer;
+  /**
+   * Proceed with symmetric encryption of `clearText` value.
+   */
+  encrypt: (
+    iv: Buffer | Uint8Array,
+    key: Buffer,
+    clearText: Buffer
+  ) => Promise<Buffer>;
+  /**
+   * Proceed with symmetric decryption of `cipherText` value.
+   */
+  decrypt: (iv: Buffer, key: Buffer, cipherText: Buffer) => Promise<Buffer>;
+  /**
+   * Generate a new private key for Symmetric encryption purposes.
+   */
   generateKeyForSymmetricEnc: () => Buffer;
-  generateIv: () => Buffer;
+  /**
+   * Generate an Initialization Vector (iv) for for Symmetric encryption purposes.
+   */
+  generateIv: () => Uint8Array;
 }
 
 export let symmetric: Symmetric = {} as unknown as Symmetric;
 
 import('./browser')
   .then((mod) => {
-    symmetric = mod as unknown as Symmetric;
+    symmetric = mod;
   })
   .catch((eBrowser) => {
     import('./node')

src/lib/waku_message/symmetric/node.ts

@@ -1,13 +1,14 @@
 import { createCipheriv, createDecipheriv, randomBytes } from 'crypto';
 
-import { IvSize, SymmetricKeySize } from './index';
+import { IvSize, SymmetricKeySize, TagSize } from './index';
 
 const Algorithm = 'aes-256-gcm';
 
-/**
- * Proceed with symmetric encryption of `clearText` value.
- */
-export function encrypt(iv: Buffer, key: Buffer, clearText: Buffer): Buffer {
+export async function encrypt(
+  iv: Buffer | Uint8Array,
+  key: Buffer,
+  clearText: Buffer
+): Promise<Buffer> {
   const cipher = createCipheriv(Algorithm, key, iv);
   const a = cipher.update(clearText);
   const b = cipher.final();
@@ -15,15 +16,14 @@ export function encrypt(iv: Buffer, key: Buffer, clearText: Buffer): Buffer {
   return Buffer.concat([a, b, tag]);
 }
 
-/**
- * Proceed with symmetric decryption of `cipherText` value.
- */
-export function decrypt(
+export async function decrypt(
   iv: Buffer,
-  tag: Buffer,
   key: Buffer,
-  cipherText: Buffer
-): Buffer {
+  data: Buffer
+): Promise<Buffer> {
+  const tagStart = data.length - TagSize;
+  const cipherText = data.slice(0, tagStart);
+  const tag = data.slice(tagStart);
   const decipher = createDecipheriv(Algorithm, key, iv);
   decipher.setAuthTag(tag);
   const a = decipher.update(cipherText);
@@ -31,16 +31,10 @@ export function decrypt(
   return Buffer.concat([a, b]);
 }
 
-/**
- * Generate a new private key for Symmetric encryption purposes.
- */
 export function generateKeyForSymmetricEnc(): Buffer {
   return randomBytes(SymmetricKeySize);
 }
 
-/**
- * Generate an Initialisation Vector (iv) for for Symmetric encryption purposes.
- */
 export function generateIv(): Buffer {
   return randomBytes(IvSize);
 }

src/lib/waku_message/version_1.ts

@@ -7,7 +7,7 @@ import * as secp256k1 from 'secp256k1';
 
 import { hexToBuf } from '../utils';
 
-import { IvSize, symmetric, TagSize } from './symmetric';
+import { IvSize, symmetric } from './symmetric';
 
 const FlagsLength = 1;
 const FlagMask = 3; // 0011
@@ -146,7 +146,7 @@ export async function encryptSymmetric(
   const iv = symmetric.generateIv();
 
   // Returns `cipher | tag`
-  const cipher = symmetric.encrypt(iv, hexToBuf(key), Buffer.from(data));
+  const cipher = await symmetric.encrypt(iv, hexToBuf(key), Buffer.from(data));
   return Buffer.concat([cipher, iv]);
 }
 
@@ -164,13 +164,11 @@ export async function decryptSymmetric(
   key: Uint8Array | Buffer | string
 ): Promise<Uint8Array> {
   const data = Buffer.from(payload);
-  const ivStart = payload.length - IvSize;
-  const tagStart = ivStart - TagSize;
-  const cipher = data.slice(0, tagStart);
-  const tag = data.slice(tagStart, ivStart);
+  const ivStart = data.length - IvSize;
+  const cipher = data.slice(0, ivStart);
   const iv = data.slice(ivStart);
 
-  return symmetric.decrypt(iv, tag, hexToBuf(key), cipher);
+  return symmetric.decrypt(iv, hexToBuf(key), cipher);
 }
 
 /**

src/tests/browser/version_1.spec.ts

@@ -5,7 +5,9 @@ import {
   clearDecode,
   clearEncode,
   decryptAsymmetric,
+  decryptSymmetric,
   encryptAsymmetric,
+  encryptSymmetric,
   getPublicKey,
 } from '../../lib/waku_message/version_1';
 
@@ -54,4 +56,19 @@ describe('Waku Message Version 1', function () {
       )
     );
   });
+
+  it('Symmetric encrypt & Decrypt', async function () {
+    await fc.assert(
+      fc.asyncProperty(
+        fc.uint8Array(),
+        fc.uint8Array({ minLength: 32, maxLength: 32 }),
+        async (message, key) => {
+          const enc = await encryptSymmetric(message, key);
+          const res = await decryptSymmetric(enc, key);
+
+          expect(res).deep.equal(message);
+        }
+      )
+    );
+  });
 });