🔐 Encrypted Messaging System

A secure terminal-based messaging application built with C# (.NET 9), featuring AES-256 encryption, PBKDF2 password hashing, and a beautiful Gruvbox-themed TUI.

✨ Features

• 🔒 AES-256 Encryption - All messages encrypted before storage
• 🔑 PBKDF2 Password Hashing - Secure user authentication (100k iterations)
• 📨 Real-time Messaging - Send, receive, edit, and delete messages
• 👑 Admin Panel - User management with protected accounts
• 🔔 Notification System - Badge indicators for unread messages
• 🔄 Manual Refresh - Check for new messages on-demand
• 🎨 Gruvbox Theme - Beautiful terminal interface with Spectre.Console
• 💾 SQLite Database - Lightweight with ADO.NET
• 🖥️ Cross-platform - Works on Windows, Linux, and macOS

🚀 Quick Start

Prerequisites

• .NET 9 SDK

Installation

# Clone the repository
git clone https://github.com/defaltastra/encrypted-messaging.git
cd encrypted-messaging

# Restore dependencies
dotnet restore

# Build and run
dotnet run

🎮 Usage

Regular User

1. Register an account or Login
2. Send encrypted messages to other users
3. View received messages (auto-marked as read)
4. Edit/delete your sent messages
5. Use 🔄 Rafraîchir to check for new messages

Admin Access

• Username: admin
• Password: admin

Admin capabilities:

• Create users with the ADMIN_ prefix
• Modify/delete only admin-created accounts
• View system statistics
• Self-registered users are protected

🏗️ Architecture

EncryptedMessaging/
├── Models/          # User and Message entities
├── Security/        # AES encryption & password hashing
├── Data/            # SQLite repositories (ADO.NET)
├── Services/        # Business logic
└── UI/              # Spectre.Console interface

Database Schema

Users Table

- Id (INTEGER PRIMARY KEY)
- Username (TEXT UNIQUE)
- PasswordHash (TEXT)
- CreatedAt (TEXT)

Messages Table

- Id (INTEGER PRIMARY KEY)
- SenderId (INTEGER FK)
- ReceiverId (INTEGER FK)
- EncryptedContent (TEXT)
- SentAt (TEXT)
- IsRead (INTEGER)

🔐 Security

• Encryption: AES-256-CBC with PKCS7 padding
• Password Hashing: PBKDF2-HMAC-SHA256 (100k iterations, 128-bit salt)
• Message Storage: All messages encrypted at rest
• Admin Protection: User-created accounts cannot be modified by admin

⚠️ Note: In production, encryption keys should be stored securely (Azure Key Vault, environment variables, etc.)

📦 Dependencies

<PackageReference Include="Spectre.Console" Version="0.49.1" />
<PackageReference Include="System.Data.SQLite.Core" Version="1.0.119" />
<PackageReference Include="Microsoft.AspNetCore.Cryptography.KeyDerivation" Version="9.0.0" />

🎨 Screenshots

🤝 Contributing

Contributions are welcome! Feel free to:

• Report bugs
• Suggest features
• Submit pull requests

📄 License

This project is licensed under the GPL License.

🙏 Acknowledgments

• Built with Spectre.Console
• Inspired by secure messaging principles
• Gruvbox color scheme

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