Abstract
Access control systems are essential for safeguarding physical and digital resources in modern institutions. This paper presents the design and implementation of a secure Near Field Communication (NFC)-based access control system tailored for university hostel entry at the University of Abuja. The system leverages a Raspberry Pi, NFC reader, physical NFC cards, and a cloud-based infrastructure (AWS Lambda and Firestore) to validate and manage user credentials in real time. An accompanying Android application enables administrators to write credential data to NFC cards and dynamically manage user access privileges. Comprehensive testing demonstrated the system’s capability to authenticate valid users and deny unauthorized access with 100% accuracy. Response times were below 1 second, ensuring minimal congestion at entry points. Moreover, the system offers convenient real-time updates and intuitive visual/audio feedback, enhancing both security and usability. Experimental results confirm that NFC-based access control significantly reduces administrative overhead, improves security, and mitigates congestion issues.

Key words: Access control systems, Near Field Communication (NFC), Raspberry Pi, AWS Lambda, Firestore, Android application, real-time database.