dev_guard 1.0.2

A high-performance remote licensing and app-protection plugin for Flutter. Secured by HMAC signatures and native FFI (Secure Enclave), it enables developers to remotely lock, warn, or sync application [...]

DevGuard (Flutter)

Protect your apps. Get paid. DevGuard is a remote licensing and application-protection layer for Flutter. Remotely lock, warn, wipe, and monitor your published apps from the DevGuard dashboard — ideal for agencies and developers who need to enforce payment terms or revoke access to client deliverables. Security-critical operations (HMAC signing, the shared secret, GZip telemetry) run inside the compiled devguard_core FFI library so your keys never sit in plain Dart.

👉 Create your free account and grab your keys at devguard.uk. You'll need a Project ID and a Master Secret to initialize the SDK.

📱 How it looks

The Lock Screen, warning banner, and diagnostics overlay are all built in — you don't build any UI. DevGuard renders the right screen automatically based on the status returned by your dashboard.

Active & Protected Your app runs normally · ACTIVE	In-App Warning Non-blocking banner (e.g. payment reminder) · WARNING	Access Suspended Automatic Lock Screen with your support contacts · LOCKED

✨ Features

• Glassmorphic Lock Screen: Premium, built-in UI that blocks access instantly — with your WhatsApp / Email / Call support buttons and an optional unlock-key entry.
• Native Security: HMAC signing and the shared secret are handled in compiled C++ (devguard_core) to prevent secret extraction.
• GZip Tunneling: Compact telemetry payloads for minimum data usage.
• Remote Config: Access server-defined JSON settings via GuardResponse.extraData and betaFeatures.
• Heartbeat & Sync: Automated background pings (with lifecycleSync / syncPolicy support) to keep license status fresh.
• Hardware Fingerprinting: Robust device identity that survives app re-installs.
• Emulator Blocking: When the project enables blockEmulators, the SDK locks on emulators/simulators automatically.
• Hardened Remote Wipe: Nonce-based remote wipe clears the response cache, usage logs, local diagnostic vault, and stored device-user identity.
• Privacy-Gated Telemetry: Advanced metrics (RAM, storage, battery, network) are only collected after the server enables advancedTelemetry.

🚀 Getting Started

1. Create your DevGuard account

1. Sign up at devguard.uk.
2. Create a Project in the dashboard.
3. Copy your Project ID and Master Secret (Settings → Master Secret). You'll pass both to the SDK below.

2. Install

dependencies:
  dev_guard: ^1.0.2

Or via Git:

dependencies:
  dev_guard:
    git:
      url: https://github.com/DevGuard-uk/dev_guard.git
      ref: v1.0.2

3. Platform setup

Requirements

• Flutter SDK ≥ 3.41 · Dart ≥ 3.11
• iOS 13+ · Android minSdk 21+
• Android build toolchain (required by current transitive plugins): Java 17, Kotlin 2.2.0, Android Gradle Plugin ≥ 8.12.1, Gradle wrapper ≥ 8.13

Android

Add to AndroidManifest.xml (lock-screen contact links):

<queries>
  <intent>
    <action android:name="android.intent.action.VIEW" />
    <data android:scheme="mailto" />
  </intent>
  <intent>
    <action android:name="android.intent.action.VIEW" />
    <data android:scheme="tel" />
  </intent>
</queries>

iOS

Add to Info.plist (contact links + jailbreak detection via root_jailbreak_guard):

<key>LSApplicationQueriesSchemes</key>
<array>
  <string>cydia</string>
  <string>mailto</string>
  <string>tel</string>
  <string>whatsapp</string>
</array>

4. Protect your app

Initialize DevGuard before calling runApp, then wrap your app with DevGuard.wrap. Once the status returned by your dashboard is LOCKED, the Lock Screen appears automatically.

import 'package:flutter/material.dart';
import 'package:dev_guard/dev_guard.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await DevGuard.init(
    projectId: 'your_project_id',   // From the DevGuard dashboard
    secret: 'YOUR_MASTER_SECRET',   // Settings → Master Secret
    failSafe: FailSafe.open,        // FailSafe.closed locks when offline with no cache
  );

  runApp(DevGuard.wrap(child: const MyApp()));
}

🧭 Status lifecycle

DevGuard syncs on app launch, on foreground/background, and on a server-defined heartbeat. The current status drives what the user sees:

Status	Meaning	What the user sees
ACTIVE	Valid license / access granted.	Your app, running normally.
WARNING	App still works, but a notice is shown.	A non-blocking banner at the top (e.g. "Payment reminder").
LOCKED	Access revoked by you.	The built-in Lock Screen.
EXPIRED	License expired.	Treated as locked.
PENDING	Initial state before the first successful sync (failSafe: open).	Your app (optimistic).
ERROR	Sync failed.	Depends on failSafe (see below).

🪝 API

DevGuard.init parameters

Parameter	Type	Default	Description
projectId	String	required	Your DevGuard project ID.
secret	String	—	Your account Master Secret (Settings → Master Secret).
failSafe	FailSafe	FailSafe.open	Offline-with-no-cache behavior. open keeps the app usable; closed locks it.
statusUrl	String?	production API	Optional custom API endpoint.

Reactive status

StreamBuilder<GuardResponse?>(
  stream: DevGuard.onStatusChanged,
  initialData: DevGuard.currentResponse,
  builder: (context, snapshot) {
    final status = snapshot.data?.status;
    // React to ACTIVE / WARNING / LOCKED
    return MyWidget();
  },
);

API	Description
DevGuard.currentResponse	Latest GuardResponse (or null before first sync).
DevGuard.onStatusChanged	Stream of status updates from the server.
DevGuard.syncStatus()	Manually trigger a license sync.
DevGuard.setDeviceUser(...)	Register the signed-in app user so they appear in the Developer Portal.

Track app users in the Developer Portal

When someone signs in or registers in your app, pass their profile to DevGuard. You'll then be able to see how many users are using your application in the Developer Portal — total user count, recent activity, and basic profile fields (username, email, phone, and any custom metadata you attach).

Call this after login or registration (all parameters are optional):

await DevGuard.setDeviceUser(
  username: 'jane_doe',
  email: '[e-mail]',
  phone: '[phone]',
  customData: {'plan': 'pro'},
);

Open Developer Portal → Users to view your app's user base and engagement.

Custom events

UsageLogger.logEvent('purchase_clicked', data: {'plan': 'pro'});

🐞 Diagnostic Overlay

To view telemetry and logs directly inside the running app:

1. Go to your DevGuard Admin Control Center.
2. Configure a 6-digit Diagnostic Passcode.
3. Toggle on Enable Diagnostic Logs (beta feature) for the desired devices.
4. A floating bug icon appears in your app.
5. Tap it and enter your passcode to view device telemetry and diagnostic vaults.

⚙️ Configuration

Fail-Safe Modes

• FailSafe.open (Default): If the server is unreachable and no cache exists, the app remains accessible.
• FailSafe.closed: The app locks until a successful status is fetched.

Optional: Passive GPS (Advanced Telemetry)

When Advanced Telemetry is enabled in the Admin Panel, the plugin may attach a cached GPS coordinate during sync. DevGuard never prompts for location during sync — your host app must request permission separately.

Android (AndroidManifest.xml):

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

iOS (Info.plist):

<key>NSLocationWhenInUseUsageDescription</key>
<string>Used for device telemetry when advanced telemetry is enabled.</string>

🔐 Security Best Practices

1. Release builds: Always build release with --obfuscate --split-debug-info=./debug_info:

   flutter build apk --obfuscate --split-debug-info=./debug_info
   flutter build ios --obfuscate --split-debug-info=./debug_info
   

2. Native hardening: Wire protocol and lock-screen integrity are protected inside the compiled native library.
3. Master Secret: Never commit your Master Secret to source control.
4. Response signing: Invalid server response signatures lock the app immediately.
5. Jailbreak / root: Compromised devices are locked via root_jailbreak_guard.

💬 Support & Contact

• 🌐 Website / register: devguard.uk
• 📧 Email: [e-mail]
• 🐛 Issues: GitHub Issues

📄 License

MIT © DevGuard

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