Cryptographic validation of Scuttlebutt messages

Usage no npm install needed!

<script type="module">
  import ssbValidate2RsjsWasm from '';



Cryptographic validation of Scuttlebutt messages using WebAssembly.

Perform batch verification and validation of SSB message values using ssb-verify-signatures and ssb-validate from the Sunrise Choir in the browser.

The wasm-bindgen and wasm-bindgen-rayon crates are currently used to generate WASM from Rust code.


npm install ssb-validate2-rsjs-wasm

Assuming you are using a bundler that supports understanding new Worker() such as Parcel, you import this library like this (ES Modules):

import * as validate from "ssb-validate2-rsjs-wasm";

Or like this (CommonJS):

const validate = require('ssb-validate2-rsjs-wasm');

And then all its APIs are callback-based, but you must call ready() first, just once. Note that the messages are expected to be message value objects (not KVT objects). An array of keys is returned on success:

const hmacKey = null;

validate.ready(() => {
  validate.verifySignatures(hmacKey, [msg1, msg2], (err, res) => {
    if (err) console.log(err);
    // print the keys array (includes keys for msg1 and msg2, in order)
    else console.log(res);


Rust first needs to be installed in order to compile to WASM (installation instructions). Also ensure that clang version 10 or higher is installed (system dependency).

git clone
cd ssb-validate2-rsjs-wasm
# install wasm-pack tool
cargo install wasm-pack
# add wasm target for rust compiler
rustup target add wasm32-unknown-unknown
# generate release build of ssb-validate2-rsjs-wasm
npm run build
# run the tests
npm run test

The build process creates JavaScript and WASM artifacts in ./pkgs/. This includes automatically-generated JavaScript code to initialize and handle web workers when running the WASM module in the browser (required for threading support).

If you wish to rebuild the WASM module after making changes to the code, use the wasm-pack tool:

wasm-pack build --target web

The tool can also compile for alternative target environments. See the deployment guide for more information.

The build process also includes bundling with webpack. Webpack outputs the bundled assets to ./dist/. One advantage of the bundled approach is that the resulting code runs in Firefox without the need to include a Module Workers polyfill.


Tests for single-author and multi-author messages are included. These tests are defined using jasmine and are executed with karma. The tests and related artifacts, such as JSON messages, can be found in the test directory. Test configuration for karma can be found in karma.conf.js in the root of this repo.

As stated in the Build section above, the tests can be run with npm run test. Note that these tests currently only run in Chrome / Chromium. If you are using Chromium, you may have to export the path as an environment variable before running the tests:

export CHROME_BIN=/usr/bin/chromium

If you wish to debug the tests it is recommended to set singleRun: false, in the karma.conf.js configuration file. This will leave the browser open after the tests have run. Click the debug button in the browser, open the developer tools and look at the console log for detailed output.


WebAssembly modules must be loaded and run off the main thread (aka the 'UI thread'). We utilise the Comlink library to create and manage WebWorkers to achieve the required separation. worker.js imports the WASM initialisation and wrapper methods from index.js, as well as the comlink.mjs module, and defines a Validator class. The class is exported for use in the calling module (see example/main.js or test/test.js for usage). Comlink exposes an async, RPC-like interface for our underlying WASM methods.

Releasing New Versions

To release a new version:

  1. Run npm run build
  2. Delete pkg/package.json generated from the step above
  3. Update the version number in package.json
  4. Commit with a message that starts with the word "release", e.g. release 1.1.0
  5. Run npm publish

Useful Documentation

The wasm-bindgen book provides detailed information about WebAssembly in the context of Rust.


LGPL 3.0.