NoteEncrypt 🔒

NoteEncrypt is a modern, privacy-focused Android note-taking application built with Jetpack Compose, Android KeyStore hardware-backed AES/GCM encryption, Room Database, and an immersive multi-module architectural layout.

NoteEncrypt provides zero-knowledge local storage for sensitive notes, credentials, and audio voice memos, protecting data at rest using strong cryptographic standards while offering fluid note management across 6 creative visual layout themes.

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📸 Layout Theme Gallery

Explore the 6 visual layout themes offered in NoteEncrypt:

📋 List Layout	🧱 Grid Layout	📍 Map Pin Layout

⛰️ Mountain Peak Layout	🌊 River Stream Layout	💧 Waterfall Layout

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🌟 Key Features

🔒 Hardware-Backed AES/GCM Encryption

• Android KeyStore Integration: AES keys are securely generated and stored inside the Android hardware-backed KeyStore framework (AndroidKeyStore).
• AES/GCM/NoPadding: Authenticated Encryption with Associated Data (AEAD) ensures note payload confidentiality and integrity.
• Zero-Knowledge Memory: Notes remain encrypted on disk in the Room database and are decrypted asynchronously off the UI thread only when actively viewed or edited.

🎙️ Encrypted Voice Memos & Audio Recording

• Integrated Voice Dictation: Capture spontaneous thoughts and audio memos directly using the device microphone (MediaRecorder).
• Animated Audio Waveform: Built-in 16-bar animated visualizer during audio playback (MediaPlayer).
• Encrypted Audio Payloads: Voice recording metadata and file references are formatted and encrypted alongside note titles.

🎨 6 Creative Thematic Visual Layouts

Switch effortlessly between custom visual card shape geometries and rendering styles:

1. 📋 List: Classic folded notepad paper sheet layout (NotepadSheetShape).
2. 🧱 Grid: 2-column brick tile layout (BrickTileShape).
3. 📍 Map Pin: Location marker card layout (MapPinShape).
4. ⛰️ Mountain Peak: Alpine summit silhouette card layout (MountainPeakShape).
5. 🌊 River Stream: Wave-curved layout with horizontal color gradients (RiverStreamShape).
6. 💧 Waterfall: Staggered grid layout with waterdrop-shaped cards (WaterfallDropShape).

🎯 Interactive Card Reordering & Management

• Tap-to-Target Card Moving: Tap any card to highlight it as a move target, then tap a target slot to instantly reorder notes.
• Edit & Re-Encrypt: Decrypt note contents, modify plain text or titles, and re-encrypt seamlessly.
• Tips & Guide Screen: Dedicated guide screen presenting note-taking best practices, security overview, and dictation tips.

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🏗️ Project Architecture & Modules

NoteEncrypt follows clean architecture principles organized across 3 Gradle sub-projects:

NoteEncrypt/
├── app/                  # Main Android Application module (UI, Navigation, ViewModel)
│   └── src/main/java/com/example/noteencrypt/
│       ├── MainActivity.kt        # Entry point & Navigation host
│       ├── NoteViewModel.kt       # StateFlow / Compose State business logic
│       ├── SecureNotesUI.kt       # Main dashboard, layout engines & custom card shapes
│       ├── EditScreen.kt          # Note editing, decryption & audio preview
│       ├── TipsScreen.kt          # Best practices & note-taking guide screen
│       ├── VoiceMemoManager.kt    # MediaRecorder & MediaPlayer audio controller
│       └── ui/theme/              # Material 3 Color, Theme, & Type definitions
├── encryption/           # Cryptographic Security Library module
│   └── src/main/java/com/example/encryption/
│       └── KeyStoreHelper.kt      # Android KeyStore secret key generation, AES/GCM encrypt/decrypt
└── data/                 # Data Persistence Library module
    └── src/main/java/com/example/data/
        ├── Note.kt                # Room Entity definition (@Entity)
        ├── NoteDao.kt             # Data Access Object (@Dao)
        ├── NoteDatabase.kt        # RoomDatabase singleton configuration
        └── NoteRepository.kt      # Repository abstraction layer (Dispatchers.IO)

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🛠️ Tech Stack & Dependencies

• Language: Kotlin
• UI Framework: Jetpack Compose with Material 3 Design System
• Navigation: Jetpack Navigation Compose
• Database: Room Database with KSP annotation processor
• Security: Hardware-Backed Android KeyStore with AES/GCM/NoPadding
• Audio Processing: MediaRecorder & MediaPlayer
• Concurrency: Kotlin Coroutines (Dispatchers.IO, Dispatchers.Main)

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🚀 Getting Started

Prerequisites

• Android Studio: Ladybug / 2024.2+ or Android Studio Jellyfish / Koala.
• JDK: Java 11 or higher.
• Min SDK: API 26 (Android 8.0 Oreo).
• Target SDK: API 37.

Building & Running

1. Clone or extract the repository:

   git clone https://github.com/your-username/NoteEncrypt.git
   cd NoteEncrypt

2. Open the project folder in Android Studio.
3. Allow Gradle to sync dependencies automatically.
4. Select the :app run configuration and click Run (or press Shift + F10) on an Android Virtual Device (emulator) or connected physical device.

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🧪 Testing

The project includes both local unit tests and instrumented tests across all three modules (:app, :data, :encryption).

To run unit tests via Gradle:

./gradlew test

To run instrumented Android tests on a connected device/emulator:

./gradlew connectedAndroidTest

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📄 License

Distributed under the MIT License. See LICENSE for more information.