FortiChat – Encrypted Client–Server Messaging System

1. Project Overview

Secure communication is essential in modern networked systems. FortiChat is a terminal-based encrypted messaging system in C++.
It supports multiple clients connecting to a TCP server and features:

• Encrypted client–server messaging
• Multi-client support with threads
• Secure user authentication
• Admin moderation: ban, kick, restrict
• Violation tracking & IP-based blocking
• Streak system & leaderboard
• Persistent logging of users, bans, and actions

2. Tech Stack

• Language: C++
• Networking: Berkeley Sockets (TCP)
• Cryptography: OpenSSL (SHA-256, AES-256, 3DES)
• Concurrency: POSIX Threads
• Platform: Linux / WSL

3. Project Structure

FortiChat/
│── src/
│   ├── server.cpp
│   └── client.cpp
│── README.md
│── .gitignore

4. Setup & Usage

g++ src/server.cpp -o server -lssl -lcrypto -pthread
./server

g++ src/client.cpp -o client -lssl -lcrypto
./client

5. Major Components

5.1 Server Module (server.cpp)

Responsibilities:

• Handle multiple clients concurrently
• Authentication & session management
• Admin moderation (ban, kick, restrict)
• Persistent storage for bans and logs

Admin Commands

users          - List connected users
ban <user>     - Ban a user
unban <user>   - Remove ban
delete <user>  - Delete account
kick <user>    - Disconnect user
restricted     - Show banned users
violations     - Show violations
blocked        - Show blocked IPs
logs           - View logs
broadcast <m>  - Message all users
status         - Server status
help           - Show commands
exit           - Graceful shutdown

5.2 Client Module (client.cpp)

Responsibilities:

• Connect to server (127.0.0.1:8080)
• Handle secure authentication
• Send/receive encrypted messages
• Respond to server admin actions

Client Commands

help
broadcast <message>
private <message>
streak
leaderboard
rules
delete
exit

6. Security & Cryptography

6.1 SHA-256 Hashing

• Used for password hashing, identity verification, and data integrity
• Workflow: Password → SHA-256 → Hash → Server Verification

6.2 AES-256 Encryption (Primary)

• Encrypts messages, session tokens, and sensitive commands
• Modes: CBC or ECB
• Fast, secure, standard across OS

6.3 3DES Encryption (Fallback)

• Used if AES unavailable
• Pros: Simple, legacy compatibility
• Cons: Slower, lower security margin

8. Logging & Monitoring

• admin_logs.txt – Admin actions
• violation_logs.txt – User violations
• restricted_users.txt – Persistent bans
• users.txt – Credentials and streaks

9. Learning Outcomes

• Secure socket programming
• Encryption and hashing techniques
• Multi-threaded network design
• Moderation and logging systems
• Security-aware C++ development

10. Limitations

• Terminal-based interface
• No TLS (custom encryption layer)
• File-based storage only
• Session keys stored in memory

11. Ethical & Legal Notice

• For educational and experimental purposes only
• Controlled environment testing
• Misuse for unauthorized access is prohibited

12. Author & Contact

Name: Mohid Umer
Email: mohidumer112@gmail.com

FortiChat is a learning project for Linux based network programming and secure encryption solution. Feedback and collaboration are welcome.