Wasm bindings - a start

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v3
         with:
-          go-version: 1.19.2
+          go-version: 1.19.4
 
       - name: Install Mage
         run: go install github.com/magefile/mage
@@ -38,7 +38,7 @@ jobs:
       - name: Set up Go
         uses: actions/setup-go@v3
         with:
-          go-version: 1.19.2
+          go-version: 1.19.4
 
       - name: Install Mage
         run: go install github.com/magefile/mage

magefile.go

@@ -31,8 +31,22 @@ const (
 
 // Build builds the library.
 func Build() error {
-	println("Building...")
-	return sh.Run(Go, "build", "-tags", "jwx_es256k", "./...")
+
+	fmt.Println("Building...")
+	if err := sh.Run(Go, "build", "-tags", "jwx_es256k", "./..."); err != nil {
+		return err
+	}
+	return BuildWasm()
+}
+
+func BuildWasm() error {
+
+	fmt.Println("Building wasm...")
+	env := map[string]string{
+		"GOOS":   "js",
+		"GOARCH": "wasm",
+	}
+	return sh.RunWith(env, Go, "build", "-tags", "jwx_es256k", "-o", "./wasm/static/main.wasm", "./wasm")
 }
 
 // Clean deletes any build artifacts.

wasm/README.md

@@ -0,0 +1,19 @@
+# WASM bindings of ssi-sdk into javascript
+
+https://github.com/TBD54566975/ssi-sdk is the home of self soverign stuff at TBD, implented in golang. 
+We want to use this from the web as well, this minimal demo shows how.
+
+`webserver` is a sample webserver which serves up a sample js app from `static` which also contains the wasm bindings and wasm "binary".
+
+# status
+This just has some example usage of apis to start with.
+
+# building (from top level)
+
+`mage buildwasm`
+
+# running web server to test out
+
+`cd wasm && go run webserver/main.go` - then go to localhost:3000 to try it out!
+
+

wasm/main.go

@@ -0,0 +1,103 @@
+//go:build js && wasm
+
+package main
+
+import (
+	"crypto/ed25519"
+	"encoding/base64"
+	"log"
+	"syscall/js"
+	"time"
+
+	"github.com/goccy/go-json"
+
+	"github.com/TBD54566975/ssi-sdk/crypto"
+	"github.com/TBD54566975/ssi-sdk/did"
+)
+
+/*
+ * This is the glue to bind the functions into javascript so they can be called
+ */
+func main() {
+	done := make(chan struct{})
+
+	// Bind the functions to javascript
+	js.Global().Set("sayHello", js.FuncOf(sayHello))
+	js.Global().Set("generateKey", js.FuncOf(generateKey))
+	js.Global().Set("makeDid", js.FuncOf(makeDid))
+	js.Global().Set("resolveDid", js.FuncOf(resolveDid))
+
+	for {
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					log.Println("Recovered from panic:", r)
+					time.Sleep(time.Second)
+				}
+			}()
+
+			<-done
+		}()
+	}
+}
+
+// 1. Simplest function - note we wrap things with js.ValueOf (if a primitive you don't technically need to)
+func sayHello(_ js.Value, args []js.Value) interface{} {
+	return js.ValueOf("Hello from golang via wasm!")
+}
+
+// 2. Calling a ssi-sdk function directly - but returning a plain old string
+// TODO: check arg lentgh and return an error if not correct
+func generateKey(_ js.Value, args []js.Value) interface{} {
+
+	keyType := args[0].String()
+	kt := crypto.KeyType(keyType)
+	if !crypto.IsSupportedKeyType(kt) {
+		return js.ValueOf("Unknown key type")
+	}
+	publicKey, _, _ := crypto.GenerateKeyByKeyType(kt)
+	pubKeyBytes, _ := crypto.PubKeyToBytes(publicKey)
+	return js.ValueOf(base64.StdEncoding.EncodeToString(pubKeyBytes))
+}
+
+// 3. Returning a richer object, converting to json and then unmarshalling to make it a js object
+func makeDid(_ js.Value, args []js.Value) interface{} {
+
+	pubKey, _, _ := crypto.GenerateKeyByKeyType(crypto.Ed25519)
+	didKey, _ := did.CreateDIDKey(crypto.Ed25519, pubKey.(ed25519.PublicKey))
+	result, _ := didKey.Expand()
+
+	// unmarshall into json bytes, then back into a simple struct for converting to js
+	resultBytes, _ := json.Marshal(result)
+	var resultObj map[string]interface{}
+	json.Unmarshal(resultBytes, &resultObj)
+	return js.ValueOf(resultObj)
+
+}
+
+func resolveDid(_ js.Value, args []js.Value) interface{} {
+
+	didString := args[0].String()
+	resolvers := []did.Resolution{did.KeyResolver{}, did.WebResolver{}, did.PKHResolver{}, did.PeerResolver{}}
+	resolver, err := did.NewResolver(resolvers...)
+	if err != nil {
+		return err
+	}
+
+	doc, err := resolver.Resolve(didString)
+	if err != nil {
+		return err
+	}
+
+	resultBytes, err := json.Marshal(doc)
+	if err != nil {
+		return err
+	}
+	var resultObj map[string]interface{}
+	err = json.Unmarshal(resultBytes, &resultObj)
+	if err != nil {
+		return err
+	}
+
+	return js.ValueOf(resultObj)
+}

wasm/static/index.html

@@ -0,0 +1,31 @@
+<html>
+
+<head>
+  <meta charset="utf-8" />
+  <script src="wasm_exec.js"></script>
+  <script>
+    const go = new Go();
+    WebAssembly.instantiateStreaming(fetch("main.wasm"), go.importObject).then((result) => {
+      go.run(result.instance);
+    });
+  </script>
+</head>
+
+<body>
+  <div>
+    <h1>WASM SSI-SDK Example</h1>
+    <button id="generateKey">generateKey</button>
+  </div>
+  <script>
+
+    const generateKeyBtn = document.querySelector("#generateKey");
+    generateKeyBtn.addEventListener("click", e => {
+      alert(sayHello());
+      alert(generateKey("Ed25519"));      
+      console.log(resolveDid("did:peer:0z6MkpTHR8VNsBxYAAWHut2Geadd9jSwuBV8xRoAnwWsdvktH"));
+      console.log(makeDid());      
+    });
+  </script>
+</body>
+
+</html>