🏢 DFA-based Smart Building Access Control System

📄 Description
This project implements a Deterministic Finite Automaton (DFA) based Access Control System for a smart building. Each restricted zone is secured by a 🔒 unique sequence of authentication methods, ensuring step-by-step verification. The system validates user authentication and strictly enforces sequence rules, rejecting any incorrect, missing, or extra steps.

Implemented in Python, this project includes:

• 📌 DFA design for each building zone
• 📌 Transition tables for all input symbols and states
• 📌 State diagrams for visualization
• 📌 Test cases covering normal, edge, and invalid inputs

✨ Features

• 🏷️ Zone-specific access control: Each zone has a predefined authentication sequence
• ✅ Strict sequence enforcement: Access granted only when the exact sequence is followed
• ⚠️ Error handling: Invalid symbols, wrong order, missing steps, and extra inputs are rejected
• 🔧 Dynamic scalability: Add new zones or authentication methods without major redesign
• 🖥️ User-friendly interface: Shows authentication symbols and available zones

🔑 Authentication Symbols

Symbol	Authentication Method
C	Card Swipe
F	Fingerprint
R	Retina Scan
S	Face Recognition
V	Voice Recognition
P	PIN Entry
B	Biometric Combo
A	Admin Override

🏢 Available Zones

• Lobby
• Server Room
• Laboratory
• Executive Lounge
• Research Wing
• Conference Hall
• Data Center
• Admin Office

🛠 How to Run

1. Clone the repository:

   git clone https://github.com/YourUsername/DFA_SmartBuildingAccess.git

2. Navigate to the project folder:

   cd DFA_SmartBuildingAccess

3. Run the Python program:

   python access_control.py

4. Follow the on-screen prompts to select a zone and enter the authentication sequence
5. Type exit to quit the program

🖥 Sample Usage

Correct Sequence Example:

Enter Zone Name (or type 'exit' to quit): Lobby
Enter authentication sequence (symbols separated by space, e.g., C F R B): C F R B

✅ Access Granted ✅

Invalid Sequence Example:

Enter Zone Name: Server Room
Enter authentication sequence: C F R B

❌ Access Denied ❌

📊 DFA Design Overview

• States (Q): Represent progress of authentication
• Start State (q0): No authentication done
• Intermediate States: Each represents successful completion of a step
• Accept State: Full sequence completed, access granted
• Reject State (qr): Any invalid input, incorrect order, missing steps, or extra input
• Input Alphabet (Σ): {C, F, R, S, V, P, B, A}

🧪 Testing
Tested with multiple real-world scenarios:

Test Case	Zone	Input Sequence	Expected Output	Actual Output	Pass/Fail
1	Lobby	C F R B	✅ Access Granted	✅ Access Granted	Pass
2	Server Room	C F R B	❌ Access Denied (wrong final step)	❌ Access Denied	Pass
3	Laboratory	C F R	❌ Access Denied (partially complete)	❌ Access Denied	Pass
4	Executive Lounge	C F R S P	❌ Access Denied (extra input)	❌ Access Denied	Pass
5	Research Wing	C X B P	❌ Invalid Symbol → Access Denied	❌ Invalid Symbol → Access Denied	Pass

🎯 Conclusion
This DFA-based smart building access control system ensures secure, deterministic, and scalable authentication for multiple zones. Python implementation provides:

• 🔄 Dynamic sequence validation
• 📈 Clear state transitions
• ⚡ Robust error handling

It demonstrates a practical application of formal automata theory in modern security systems.