stealth_enum 1.0.3

Obfuscates Dart enums into zero-cost extension types backed by high-entropy integers, eliminating enum metadata from Flutter AOT binaries.

A Zero Overhead Dart & Flutter code generator that hides enum metadata, randomizes enum values, and makes AOT binaries harder to reverse engineer (REA, Blutter, Ghidra etc.).

The Issue : (

You maybe already doing:

✅ --obfuscate --split-debug-info=.
✅ SSL Certificate Pinning.
✅ App Attest & App Integrity.
✅ freeRasp.
✅ flutter_secure_storage.
✅ envied.

Do you feel like you are protected? Yes, but there's a small catch when it comes to reverse engineering.

❌ Dart enums still expose their names intentionally in compiled AOT binaries.

The Solution : )

When you compile a Flutter app with --obfuscate --split-debug-info, Dart strips class and function symbols. But enum identifier strings are intentionally preserved in the Dart Object Pool (pp.txt in Blutter) just to support .name and .toString().

AI assisted reverse engineering pipelines like REA (Reverse Engineer Anything), Blutter, and Ghidra use these plain text strings as anchors. They locate the string in decompiled assembly, trace cross-references back to your obfuscated business logic, and reconstruct your licensing, authentication, and security checks.

Standard enums also compile to sequential indices (0, 1, 2, 3), creating predictable jump tables that decompilers immediately identify.

// What Blutter sees in pp.txt (Standard Enum):
"SubscriptionStatus"  "trial"  "active"  "expired"  "cancelled"

// What Ghidra sees in ARM64 (With stealth_enum):
CMP W0, #0x4B91E20A   // Is it a math constant? Hash? Memory offset?
CMP W0, #0x7C104F8B
CMP W0, #0x1D55A9C3

What to change in the code?

Not much! Just make your enums private and add @StealthEnum() annotation to it just like the image below:

Sabaaaash! That's it! You just protected yourself from simple AI assisted reverse engineering attacks.

Now run:

dart run build_runner build --delete-conflicting-outputs
# or for Flutter:
flutter pub run build_runner build --delete-conflicting-outputs

And enjoy using the same enum class with same enum name as if nothing has changed just like below image!

Table of Contents

• Compatibility
• Features
• Getting started
• Usage
  • 1. Annotate a private enum
  • 2. Run the code generator
  • 3. Use the generated extension type
  • Custom seed for deterministic builds
  • Custom type name
• Generated Output
• API Reference
  • @StealthEnum
  • Generated Extension Type
• Under the Hood
• Running the example
• Contributing
• License

Compatibility

stealth_enum is implemented entirely in pure Dart. So don't worry about:

• iOS Swift Package Manager (SPM): 100% compatible. Requires no CocoaPods or native SPM configuration.
• Android Gradle Plugin (AGP 9.0+): 100% immune to Kotlin Gradle Plugin (KGP) deprecations and breaking changes.

Features

• Zero Binary String Footprint: Completely removes enum and constant names from compiled AOT binaries.
• Non-Sequential Entropy: Replaces predictable sequential indices with high-entropy 32-bit hex values.
• Zero Runtime Overhead: Built on Dart 3.3+ extension type const over primitive int with zero heap allocation and zero boxing.
• Inlined Pattern Matching: @pragma('vm:prefer-inline') on .when() and .maybeWhen() inlines branches directly into call sites.
• No StateError String Leaks: The fallback branch in .when() uses a wildcard _ => rather than throwing an exception with class names.
• Guaranteed Tree-Shaking: The private annotated enum (_MyEnum) is discarded by the compiler; only the lightweight extension type remains.
• Deterministic CI Builds: Optional compile-time seed parameter guarantees reproducible builds across team members and CI pipelines.
• Pure Dart: Zero native code, zero CocoaPods or Gradle headaches.

Feature	Standard Dart enum	@StealthEnum
Strings in Binary	Plain-text in Object Pool (pp.txt)	Zero strings (completely absent)
Index Pattern	Sequential 0, 1, 2, 3 (jump tables)	Non-sequential 32-bit hex (0x4B91E20A)
Runtime Cost	Wrapper object allocation	Zero (erases to raw primitive int)
Exhaustive Matching	Native switch statement	Inlined .when() / .maybeWhen()
Decompiler Visibility	Anchors for REA & Ghidra	Indistinguishable from random constants
Tree-Shaking	Kept in binary	100% tree-shaken (private source enum)

Getting started

Add stealth_enum to your pubspec.yaml:

dependencies:
  stealth_enum: ^1.0.0

dev_dependencies:
  build_runner: ^2.4.0
  stealth_enum_generator: ^1.0.0

Then run:

dart pub get
# or for Flutter:
flutter pub get

Usage

1. Annotate a private enum

Define your enum as a private enum (prefixed with _) and add the part directive:

// lib/security_clearance.dart
import 'package:stealth_enum/stealth_enum.dart';

part 'security_clearance.g.dart';

@StealthEnum()
enum _SecurityClearance {
  guest,
  operator,
  admin,
  superAdmin,
}

2. Run the code generator

Generate the obfuscated extension types using build_runner:

dart run build_runner build --delete-conflicting-outputs
# or for Flutter:
flutter pub run build_runner build --delete-conflicting-outputs

3. Use the generated extension type

The generated SecurityClearance extension type provides compile-time type safety with zero runtime cost:

import 'security_clearance.dart';

void authorize(SecurityClearance clearance) {
  // Exhaustive pattern matching (fully inlined at compile-time):
  final role = clearance.when(
    guest: () => 'Guest Access',
    operator: () => 'Operator Access',
    admin: () => 'Administrator Access',
    superAdmin: () => 'Super Admin Access',
  );
  print(role);
}

void main() {
  authorize(SecurityClearance.admin); // → "Administrator Access"

  // Partial matching with required fallback:
  final canEdit = SecurityClearance.operator.maybeWhen(
    admin: () => true,
    superAdmin: () => true,
    orElse: () => false,
  );
  print(canEdit); // → false

  // Extension types erase to int at runtime:
  assert(SecurityClearance.admin as Object is int); // true ✓

  // Direct equality check:
  if (clearance == SecurityClearance.superAdmin) {
    unlockAllDoors();
  }

  // Iterate over all values:
  for (final level in SecurityClearance.values) {
    print(level.rawValue); // prints hex int (e.g. 0x7C06254C)
  }
}

Custom seed for deterministic builds

By default, stealth_enum computes deterministic values based on symbol names and internal hashing. If you want a fixed seed across all environments or custom entropy:

@StealthEnum(seed: 0xCAFEBABE)
enum _SubscriptionTier {
  free,
  pro,
  enterprise,
}

Custom type name

By default, the public extension type name strips the leading _ from your private enum (_SecurityClearance → SecurityClearance). You can customize this with name:

@StealthEnum(name: 'AppRole')
enum _RoleInternal {
  user,
  admin,
}

Generated Output

Here is what stealth_enum_generator produces in security_clearance.g.dart:

// GENERATED CODE - DO NOT MODIFY BY HAND

part of 'security_clearance.dart';

// **************************************************************************
// StealthEnumGenerator
// **************************************************************************

extension type const SecurityClearance._(int rawValue) {
  static const SecurityClearance guest = SecurityClearance._(0x373D1B37);
  static const SecurityClearance operator = SecurityClearance._(0x764AE932);
  static const SecurityClearance admin = SecurityClearance._(0x7C06254C);
  static const SecurityClearance superAdmin = SecurityClearance._(0x3154C03F);

  static const List<SecurityClearance> values = <SecurityClearance>[
    guest,
    operator,
    admin,
    superAdmin,
  ];

  @pragma('vm:prefer-inline')
  T when<T>({
    required T Function() guest,
    required T Function() operator,
    required T Function() admin,
    required T Function() superAdmin,
  }) {
    return switch (rawValue) {
      0x373D1B37 => guest(),
      0x764AE932 => operator(),
      0x7C06254C => admin(),
      _ => superAdmin(), // Wildcard branch prevents leaking StateError strings
    };
  }

  @pragma('vm:prefer-inline')
  T maybeWhen<T>({
    T Function()? guest,
    T Function()? operator,
    T Function()? admin,
    T Function()? superAdmin,
    required T Function() orElse,
  }) {
    return switch (rawValue) {
      0x373D1B37 => guest != null ? guest() : orElse(),
      0x764AE932 => operator != null ? operator() : orElse(),
      0x7C06254C => admin != null ? admin() : orElse(),
      0x3154C03F => superAdmin != null ? superAdmin() : orElse(),
      _ => orElse(),
    };
  }
}

API Reference

@StealthEnum

Parameter	Type	Default	Description
name	String?	null	Custom name for the generated extension type. Defaults to stripping the leading _ from the enum name.
seed	int?	null	Custom 32-bit integer seed for deterministic value generation across builds.
generateWhen	bool	true	When true, generates .when() and .maybeWhen() pattern matching helpers.

Generated Extension Type

Member	Type	Description
rawValue	int	The underlying 32-bit obfuscated integer value.
values	List<T>	List of all enum variants in declaration order.
when<T>(...)	T Function(...)	Inlined exhaustive pattern matching covering all variants.
maybeWhen<T>(...)	T Function(...)	Inlined non-exhaustive pattern matching with a required orElse fallback.

Under the Hood

• Pure Extension Type: Dart 3.3 introduced extension type, which compiles down directly to the underlying representation type (int). At runtime, it lives in a CPU register with zero heap allocation and zero pointer indirection.
• Tree-Shaking: Because the source enum _SecurityClearance is private to the file and never instantiated, the Dart AOT compiler completely removes the original enum declaration, its string names, and metadata from the compiled binary.
• Decompiler Neutralization: Conventional decompilers (Blutter, Ghidra) look for string tables and incremental switch jump tables (0, 1, 2, ...). With stealth_enum, they see isolated integer comparisons (CMP W0, #0x7C06254C) scattered across inlined call sites.
• Wildcard Fallback (No String Leaks): Standard Dart switch statements may generate exception stubs referencing unhandled cases. stealth_enum maps the final case of .when() to a wildcard _ =>, eliminating any runtime error string.

Running the example

cd example
dart pub get
dart run build_runner build
dart run lib/stealth_enum_example.dart

Contributing

PRs and issues are welcome! Please open an issue first for significant changes.

License

Made with 💛 by aslamambiloly © 2026