constant_device_id 0.1.0

A Flutter plugin that provides a permanent device identifier that persists across app reinstalls. Uses Widevine DRM on Android and the system Keychain on iOS for hardware-level persistence.

constant_device_id

A Flutter plugin that provides a permanent device identifier that persists across app reinstalls.

On Android, the identifier is derived from the hardware-level Widevine DRM ID a cryptographically unique value bound to the device at manufacture time. On iOS, the identifier is stored in the system Keychain, which Apple preserves across app reinstalls by default.

Features

• Survives app uninstall and reinstall on both platforms
• Hardware backed on Android via Widevine DRM (L1 / L3)
• Keychain backed on iOS no extra configuration required
• SHA-256 hashed output raw hardware IDs are never exposed
• Four layer fallback for maximum reliability on edge case devices
• No Android permissions required
• Android 5.0+ (API 21) and iOS 12.0+ support

How It Works

ConstantDeviceId.getId() resolves the identifier through four layers in order, returning as soon as one succeeds:

Layer	Source	Survives Reinstall	Platform
0	Widevine DRM hardware ID	✅ Yes (until factory reset)	Android only
1	Secure Storage / iOS Keychain	✅ Yes (iOS) / ❌ No (Android)	Both
2	SharedPreferences	❌ No	Both
3	Generated UUID v4	❌ No	Both

On a normal Android device Layer 0 is always reached, making the ID truly permanent. On iOS, Layer 1 (Keychain) natively persists across reinstalls so the ID is equally stable.

Installation

Add the dependency to your pubspec.yaml:

dependencies:
  constant_device_id: ^0.1.0

Then fetch packages:

flutter pub get

Platform Setup

Android

No additional setup is required. The Widevine DRM API does not need any AndroidManifest.xml permissions.

Minimum SDK: 21 (Android 5.0 Lollipop)

iOS

No additional setup is required. The plugin uses flutter_secure_storage under the hood, which uses the iOS Keychain with first_unlock accessibility — items are retained after an app is deleted and reinstalled.

Minimum iOS version: 12.0

Usage

Get the permanent device ID

import 'package:constant_device_id/constant_device_id.dart';

final String deviceId = await ConstantDeviceId.getId();
print(deviceId);
// e.g. "a3f2c1d4e5b6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2"

The returned value is a 64-character lowercase hex string (SHA-256 hash), consistent across every call on the same device.

Reset locally stored ID

await ConstantDeviceId.reset();

Clears the ID from Secure Storage and SharedPreferences. On Android, the next call to getId() still returns the same hardware-derived ID because the Widevine layer is not affected by this operation.

API Reference

ConstantDeviceId.getId() → Future<String>

Returns the permanent device identifier.

• Thread-safe and idempotent — safe to call multiple times concurrently.
• Never throws under normal conditions; falls through all layers gracefully.
• Return format: 64-character SHA-256 hex string.

ConstantDeviceId.reset() → Future<void>

Clears Layers 1 and 2 (Secure Storage + SharedPreferences).

Note: On Android, Layer 0 (Widevine) is hardware derived and cannot be reset programmatically. Calling getId() after reset() will return the same ID on Android.

When Does the ID Change?

Understanding the failure modes helps you design your system accordingly.

Android

Scenario	ID changes?
App uninstall + reinstall	No Widevine persists
App update	No
Clear app data (Settings → App → Clear Data)	No Widevine persists
Factory reset	Yes — DRM keys are wiped
System update re-provisioning DRM	Rarely OEM-specific
Rooted device with tampered DRM	Yes
Emulator	Yes Widevine unavailable; falls back to UUID

iOS

Scenario	ID changes?
App uninstall + reinstall	No — Keychain persists
App update	No
Factory reset / device erase	Yes
User manually clears Keychain	Yes
Restore to a different device	Yes

Privacy

The raw Widevine hardware ID is never stored or transmitted. It is immediately hashed with SHA-256 before use, making it impossible to reverse engineer the underlying hardware identifier from the output value.

Example App

A full example is available in the example/ directory.

cd example
flutter run

Contributing

Issues and pull requests are welcome at the GitHub repository.

Please ensure new code:

• Passes flutter analyze
• Is covered by unit tests
• Follows the existing code style

License

MIT License © 2026 AppStoneLab