Calculator Vault (CalcPro) 🔒

A fully functional Scientific Calculator that doubles as a secure, AES-encrypted Photo & Video Vault.

Designed with privacy-first architecture, this app disguises itself as a standard Android calculator using Material You (Dynamic Colors). It features advanced security measures like "Ghost Mode" (hidden from Recents) and screenshot prevention.

✨ Key Features

🛡️ Security & Privacy

• Stealth Mode: App appears as a fully working Calculator in the launcher and system settings.
• Ghost Mode: The Vault activity is excluded from the "Recent Apps" list. If the user minimizes the app or presses Home, the Vault self-destructs instantly, leaving only the Calculator visible in the background.
• AES Encryption: All hidden files are encrypted. They are renamed and moved to internal private storage, making them inaccessible to other apps or file managers.
• Screenshot Block: FLAG_SECURE is enabled to prevent screen recording or screenshots within the Vault.
• Lifecycle Protection: The app detects onUserLeaveHint to instantly hide sensitive content if the user attempts to switch apps.

🔢 Calculator Functionality

• Scientific Operations: Support for sin, cos, tan, log, ln, square root, power, and factorial.
• History Tape: Scrollable calculation history (saved locally).
• Smart Logic: Parenthesis handling and percentage logic.
• Expandable UI: Smooth animation to reveal scientific functions.

🖼️ Custom Media Gallery

• Secure Viewer: Built-in secure gallery (no external apps needed).
• Smart Zoom: Custom-built ZoomImageView engine supporting smooth pinch-to-zoom, double-tap, and fling gestures.
• Pro Video Player: Custom video player with overlay controls, seek bar, and landscape toggle.
• Immersive Mode: UI controls (Share/Delete/Unhide) fade away automatically for a distraction-free viewing experience.

🎨 UI/UX

• Material You: Fully supports Android 12+ Dynamic Colors. The UI adapts to the user's system wallpaper.
• System Theme Support: Automatically switches between Light and Dark modes.
• Edge-to-Edge: Layouts implemented with fitsSystemWindows for a modern look.

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🚀 How to Use

1. Launch the App: Open "Calculator". It functions exactly like a normal calculator.
2. Unlock the Vault:
   • Enter your numeric password (Default is 1234).
   • Press the Equals (=) button.
   • The calculator interface will slide away to reveal the hidden vault.
3. Change Password (Secret Menu):
   • To access Settings, type +0+0 on the calculator display.
   • Press Equals (=).
   • The secret Settings page will open where you can update your password.
4. Hide Files: Click the + button inside the vault to select photos or videos from your device.
5. Unhide: Open a file in the vault and click the "Eye" icon to restore it to your Downloads folder.

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🛠️ Technical Stack

• Language: Kotlin
• Minimum SDK: Android 10 (API 29)
• Target SDK: Android 14 (API 34)
• Architecture: MVVM (Model-View-ViewModel) pattern concepts.
• Encryption: AES (Advanced Encryption Standard).
• Components:
  • androidx.appcompat & material (Material Design 3).
  • ConstraintLayout & GridLayout.
  • Coroutines (for background encryption tasks).
  • Coil (for efficient image loading).
  • ViewBinding.

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🔧 Installation

1. Clone the repository:

   git clone https://github.com/soul-999-ayu/CalcPro.git

2. Open the project in Android Studio.
3. Sync Gradle files.
4. Connect an Android device or start an emulator.
5. Run the app (Shift + F10).

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📝 License

This project is open-source and available under the MIT License.

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Made with ❤️ by Ayu Kashyap