/wasm-demo

In class wasm demo for Rust Vs Go

  • Get index.html from golang repo

  • Change index.html to say main.wasm

  • Get wasm_exec.js from golang repo

  • Make main.go hello world

  • Set GOOS=js

  • Set GOARCH=wasm

  • go build -o main.wasm main.go

  • Make a web server github.com/andrea-couto/golang-wasm-demo

  • Build and run the server


In order to pass values from go to javascript we need syscall/js package

HOWEVER, goland is prohibiting us from using syscall/js until we set default

OS and ARCH to JS, WASM

  • Open up syscall/js under external libraries

  • Click "Edit go project settings"

  • OS = js ARCH=wasm

  • Make a channel and JS callback in main

      c := make(chan struct{},0)

  js.Global().Set("encrypt", js.NewCallback(encrypt))

  <-c

  • Create place to take in input

    <textarea id="input" placeholder="Enter your plaintext"></textarea><br>

  • Create a place to put ciphertext (AKA output)

    <div id="output"></div><br>

  • Create a convert function

    function convert() {

     let input = document.querySelector('#input').value;

     encrypt(input, output);

}

  • change button to be convert() and removed disabled

  • add run(); to new Go()

  • Create a output function to get the innerHtml

      function output(ciphertext) {

      document.querySelector('#output').innerHTML = ciphertext;

  }

  • make an encrypt function

    func encrypt (input []js.Value) {

    PrivateKey, _ := rsa.GenerateKey(rand.Reader, 1000)

    PublicKey := &PrivateKey.PublicKey

    message := input[0].String()

    byteMessage := []byte(message)

    label := []byte("")

    hash := sha256.New()

    ciphertext, _ := rsa.EncryptOAEP(hash, rand.Reader, PublicKey, byteMessage, label)

    input[1].Invoke(fmt.Sprintf("[%x]", ciphertext))

}

  • rebuild the wasm file

    go build -o main.wasm main.go

  • rerun the server

  • can you print or display the public key?