Go WebAssembly — AES Encryption in the Browser

Created: March 18, 2023 · Last Updated: December 6, 2023

An experimental project exploring the boundary between Go and the web platform, using WebAssembly (WASM) to run Go code directly inside the browser — no server required for the encryption logic.

What is This?

This project demonstrates how to compile Go into a WebAssembly binary and call it from a standard HTML/JavaScript frontend. The core functionality is AES encryption and decryption, running entirely client-side through the compiled WASM module.

Live demo: go-web-assembly.web.app

Why Go + WebAssembly?

Go's standard library includes a solid crypto/aes implementation. By compiling it to WASM, we get:

Zero-dependency encryption in the browser — no npm crypto packages
Consistent behavior between server-side Go code and the browser
An exploration of the Go WASM toolchain and how it interacts with JavaScript

Stack

Layer	Technology
Core Logic	Go (`crypto/aes`)
Platform	WebAssembly (`GOARCH=wasm GOOS=js`)
Frontend	HTML, JavaScript, CSS
Hosting	Firebase Hosting
CI/CD	GitHub Actions

How It Works

Go's WASM build target compiles to a .wasm binary. The browser loads it using JavaScript's WebAssembly APIs with the Go-provided wasm_exec.js runtime bridge. Go functions registered via js.Global().Set(...) become callable directly from JavaScript.

// Go function exposed to JavaScript
js.Global().Set("encryptAES", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
    plaintext := args[0].String()
    key := args[1].String()
    // AES encryption logic here
    return encrypted
}))

// Called from the browser
const encrypted = encryptAES(plaintext, secretKey);

Build

GOARCH=wasm GOOS=js go build -o public/main.wasm ./src