Literature Review on Smart Door Lock Using Keypad and GSM

Abstract: Smart security systems are rapidly evolving as modern alternatives to conventional mechanical locks, offering enhanced safety, reliability, and flexibility. Among these, authentication methods that integrate embedded systems with communication technologies provide cost-effective yet secure solutions for access control. This paper presents a review and implementation of an OTP-based door lock system that combines a 4x4 keypad with a SIM800L GSM module for dynamic authentication. The system operates on a dual-layer verification mechanism: an initial password entry followed by a one-time password (OTP) sent to the registered mobile number in case of failed attempts. An Arduino Uno microcontroller is used to coordinate the process, while an LCD display provides real-time feedback to the user. This approach significantly reduces the vulnerabilities associated with static passwords, such as brute-force attacks or unauthorized sharing. The review also examines existing security mechanisms, identifies their limitations, and discusses how OTP-based GSM integration improves affordability, robustness, and usability. Future extensions may include biometric integration, IoT-based cloud monitoring, and mobile app support to further strengthen system performance and applicability.