initial working demo, basic elements styles, new go method to get lim…

…its of number of shares and threshold

cmd/webassembly/main.go

@@ -16,20 +16,33 @@ const (
 	jsClassName     = "GoSSS"
 	jsHideMethod    = "hide"
 	jsRecoverMethod = "recover"
+	jsLimitsMethod  = "limits"
 	// required number of arguments for each method
 	hidedNArgs    = 3 // msg, nshares, minshares
 	recoverdNArgs = 1 // shares
+	limitsNArgs   = 1 // msg
 )
 
-func wasmError(err error) js.Value {
-	return js.Global().Call("throwError", js.ValueOf(err.Error()))
+func wasmResult(data interface{}, err error) js.Value {
+	response := map[string]interface{}{}
+	if data != nil {
+		response["data"] = data
+	}
+	if err != nil {
+		response["error"] = err.Error()
+	}
+	result, err := json.Marshal(response)
+	if err != nil {
+		return js.ValueOf(fmt.Sprintf(`{"error": "%s"}`, err.Error()))
+	}
+	return js.ValueOf(string(result))
 }
 
 func main() {
 	gosssClass := js.ValueOf(map[string]interface{}{})
 	gosssClass.Set(jsHideMethod, js.FuncOf(func(this js.Value, p []js.Value) interface{} {
 		if len(p) != hidedNArgs {
-			return wasmError(fmt.Errorf("invalid number of arguments"))
+			return wasmResult(nil, fmt.Errorf("invalid number of arguments"))
 		}
 		msg := p[0].String()
 		nshares := p[1].Int()
@@ -40,30 +53,35 @@ func main() {
 			Min:    minshares,
 		})
 		if err != nil {
-			return wasmError(err)
+			return wasmResult(nil, err)
 		}
-		jsonShares, err := json.Marshal(shares)
-		if err != nil {
-			return wasmError(err)
-		}
-		return string(jsonShares)
+		return wasmResult(shares, nil)
 	}))
 
 	gosssClass.Set(jsRecoverMethod, js.FuncOf(func(this js.Value, p []js.Value) interface{} {
 		if len(p) != recoverdNArgs {
-			return wasmError(fmt.Errorf("invalid number of arguments"))
+			return wasmResult(nil, fmt.Errorf("invalid number of arguments"))
 		}
 		// recover the shares from the json string
 		var shares []string
 		if err := json.Unmarshal([]byte(p[0].String()), &shares); err != nil {
-			return wasmError(err)
+			return wasmResult(nil, err)
 		}
 		// recover the message
 		msg, err := gosss.RecoverMessage(shares, nil)
 		if err != nil {
-			return wasmError(err)
+			return wasmResult(nil, err)
+		}
+		return wasmResult(msg, nil)
+	}))
+
+	gosssClass.Set(jsLimitsMethod, js.FuncOf(func(this js.Value, p []js.Value) interface{} {
+		if len(p) != limitsNArgs {
+			return wasmResult(nil, fmt.Errorf("invalid number of arguments"))
 		}
-		return string(msg)
+		// recover the message
+		minShares, maxShares, minMin, maxMin := gosss.ConfigLimits([]byte(p[0].String()))
+		return wasmResult([]int{minShares, maxShares, minMin, maxMin}, nil)
 	}))
 
 	js.Global().Set(jsClassName, gosssClass)

config.go

@@ -13,6 +13,23 @@ var DefaultPrime, _ = new(big.Int).SetString("2188824287183927522224640574525727
 // using 2 bytes (255^2)
 const maxShares = 65536
 
+// ConfigLimits returns the limits for the number of shares and minimum shares
+// to recover the original message based on the message size. It returns the
+// minimum number of shares, the maximum number of shares, the minimum number
+// of shares to recover the secret, and the maximum number of shares to recover
+// the secret. The message is divided into parts based on the size of the prime
+// number used as finite field, the number of parts is used to calculate the
+// limits.
+func ConfigLimits(message []byte) (int, int, int, int) {
+	c := &Config{Prime: DefaultPrime}
+	secrets := encodeMessage(message, c.maxSecretPartSize())
+	nSecrets := len(secrets)
+	minShares := nSecrets * 3
+	minMin := nSecrets * 2
+	maxMin := maxShares - nSecrets
+	return minShares, maxShares, minMin, maxMin
+}
+
 // Config struct defines the configuration for the Shamir Secret Sharing
 // algorithm. It includes the number of shares to generate, the minimum number
 // of shares to recover the secret, and the prime number to use as finite field.

web/app.js

@@ -0,0 +1,105 @@
+import { createApp } from 'https://unpkg.com/vue@3/dist/vue.esm-browser.prod.js'
+
+const app = createApp({
+    data() {
+        return {
+            config: {
+                minShares: 0,
+                maxShares: 0,
+                minMin: 0,
+                maxMin: 0,
+            },
+            message: "",
+            sharesCount: 0,
+            threshold: 0,
+            shares: "",
+            currentTab: "hide",
+            hide_result: "",
+            recovered_message: "",
+        }
+    },
+    async created() {
+        await this.setupWebAssembly();
+    },
+    template: `
+        <div>
+            <button class="button" @click="currentTab = 'hide'">Hide</button>
+            <button class="button" @click="currentTab = 'recover'">Recover</button>
+            <div v-show="currentTab === 'hide'">
+                <h3>Hide a message</h3>
+                <textarea class="textarea" v-model="message" placeholder="Enter your message" rows="6"></textarea>
+                <div v-show="message !== ''">
+                    <label class="label">Shares <small>({{ config.minShares }} - {{ config.maxShares }})</small></label>
+                    <input v-model="sharesCount" type="number" class="input" :min="config.minShares" :max="config.maxShares" :step="config.minShares">
+                </div>
+                <div v-show="message !== ''">
+                    <label class="label">Threshold <small>({{ config.minMin }} - {{ sharesCount - 1 }})</small></label>
+                    <input v-model="threshold" type="number" class="input" :min="config.minMin" :max="sharesCount - 1">
+                </div>
+                <button class="button is-secondary" :class="{'is-disabled': message == ''}" @click="hideMessage">Hide</button>
+                <textarea class="textarea" readonly v-model="hide_result" placeholder="Resulting secret parts" rows="6"></textarea>
+            </div>
+            <div v-show="currentTab === 'recover'">
+                <h3>Recover a message</h3>
+                <textarea class="textarea" v-model="shares" placeholder="Enter shares" rows="6"></textarea>
+                <button class="button is-secondary" :class="{'is-disabled': message == ''}" @click="recoverMessage">Recover</button>
+
+                <textarea class="textarea" readonly v-model="recovered_message" placeholder="Recovered message" rows="6"></textarea>
+            </div>
+        </div>
+    `,
+    methods: {
+        async setupWebAssembly() {
+            const go = new Go();
+            const result = await WebAssembly.instantiateStreaming(fetch("gosss.wasm"), go.importObject);
+            go.run(result.instance);
+        },
+        getConfig() {
+            const rawResult = GoSSS.limits(this.message);
+            const result = JSON.parse(rawResult);
+            if (!result.error) {
+                this.config = {
+                    minShares: result.data[0],
+                    maxShares: result.data[1],
+                    minMin: result.data[2],
+                    maxMin: result.data[3],
+                }
+                if (this.sharesCount < this.config.minShares) this.sharesCount = this.config.minShares;
+                if (this.sharesCount > this.config.maxShares) this.sharesCount = this.config.maxShares;
+                if (this.threshold < this.config.minMin) this.threshold = this.config.minMin;
+                if (this.threshold > this.sharesCount - 1) this.threshold = this.sharesCount - 1;
+            } else {
+                alert(`Error getting configuration: ${result.error}`);
+            }
+        },
+        hideMessage() {
+            const rawResult = GoSSS.hide(this.message, this.sharesCount, this.threshold);
+            const result = JSON.parse(rawResult);
+            if (!result.error) {
+                this.hide_result = result.data.join("\n");
+            } else {
+                alert(`Error hiding message: ${result.error}`);
+            }
+        },
+        recoverMessage() {
+            const shares = JSON.stringify(this.shares.split("\n"));
+            const rawResult = GoSSS.recover(shares);
+            const result = JSON.parse(rawResult);
+            if (!result.error) {
+                this.recovered_message = window.atob(result.data);
+            } else {
+                alert(`Error recovering message: ${result.error}`);
+            }
+        }
+    },
+    watch: {
+        message() {
+            this.getConfig();
+        }
+    },
+    components: {
+
+    }
+});
+
+app.mount('#app');

web/index.html

@@ -1,30 +1,23 @@
-<html>
-    <head>
-        <title>Go Shamir Secret Sharing demo</title>
-    </head>
-    <body>
-        <script src="wasm_exec.js"></script>
-        <script>
-            function throwError(e) {
-                console.error(e);
-            }
-
-            function hide(message, sharesCount, threshold) {
-                let rawshares = GoSSS.hide(message, sharesCount, threshold);
-                return JSON.parse(rawshares);
-            }
-
-            function recover(shares) {
-                let message = GoSSS.recover(JSON.stringify(shares));
-                return message;
-            }
-
-            (async function() {
-                const go = new Go();
-                const result = await WebAssembly.instantiateStreaming(fetch("gosss.wasm"), go.importObject);
-                go.run(result.instance);
-            })()
-        </script>
-    </body>
-</html>
-
+<!DOCTYPE html>
+<html data-theme="light">
+	<head>
+		<!-- Required meta tags -->
+		<meta charset="utf-8">
+		<meta http-equiv="X-UA-Compatible" content="IE=edge">
+		<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
+		<!-- Title and favicon (SVG emoji)-->
+		<title>Shamir Secret Sharing Demo</title>
+		<link rel="icon"
+			href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🔐</text></svg>">
+		<!-- Siimple.css assets -->
+		<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/siimple/siimple.css" />
+	</head>
+	<body>
+		<!-- App slot -->
+		<div id="app"></div>
+		<!-- Import Go WebAssembly engine -->
+		<script src="wasm_exec.js"></script>
+		<!-- Import app -->
+		<script type="module" src="app.js"></script>
+	</body>
+</html>