GSM Based Bank Locker Security System with 3-Layer Authentication

Abstract

This paper introduces the design and development of a GSM-based banking locker security system that incorporates multilayered authentication to improve financial asset security. The system uses SIM900A GSM module to implement a three-level security mechanism: a masked 6-digit Personal Identification Number (PIN), a one-time password (OTP) as SMS to the registered mobile number through the SIM900A GSM module with a one min lockout feature for wrong OTP input, and a final key combination of special characters for final verification. Our system uses Arduino UNO to process inputs and control along with peripherals such as a keypad, LCD, buzzer, and motor driver, for secure interaction and physical access control. Our system provides instant system feedback along with real-time alerting via the GSM Module enabling proper access authorization and intrusion detection. Test results further validate the robustness of the system against unauthorized access and its efficiency in providing multi-layer authentication. Our model offers a scalable and cost-effective solutions for the secure banking infrastructure, providing potential applications in private lockers, vaults and ATM machines.

Introduction

1. Overview

• Traditional bank locker systems using mechanical keys are vulnerable to unauthorized access, key duplication, and insider breaches.

• This paper proposes a cost-effective, intelligent, and scalable GSM-based bank locker system featuring three-layer authentication and real-time monitoring to address these issues.

2. Key Features of the Proposed System

• Three-layer authentication:

  1. 6-digit masked PIN

  2. OTP via GSM (SIM900A module)

  3. Final key combination input

• Includes LCD display, buzzer for alerts, and a motor-driven locker mechanism, all controlled by Arduino UNO.

• Sends SMS alerts for incorrect inputs or unauthorized access attempts.

• Uses GSM communication (AT commands) for OTP delivery and alert messaging.

3. Advantages Over Existing Systems

4. System Architecture

• Input Unit: 4x3 keypad (for PIN and key combo)

• Output Units: LCD (status display), Buzzer (alerts), DC motor (locker operation)

• Communication: SIM900A GSM module (OTP transmission)

• Control: Arduino UNO (manages authentication flow and hardware actions)

• Power: Separate regulated power supply for GSM and shared supply for other components

5. Authentication Flow

6. GSM Communication and OTP Handling

• OTP generated as a random 6-digit numeric code.

• Sent via AT commands to user’s mobile through GSM network.

• OTP expires after a short time to enhance security.

7. Testing & Performance Results

• Case 1: All correct → Locker opens successfully.

• Case 2: Wrong PIN → Denied + buzzer/SMS.

• Case 3: Right PIN, wrong OTP → Lockout + SMS.

• Case 4: Right PIN & OTP, wrong key combo → Denied + buzzer/SMS.

• Response times: OTP sent in 5–7 seconds; motor operated in 4 seconds.

• High reliability and accurate access control across tests.

8. Limitations

• SIM spoofing risk in GSM communication.

• Potential brute-force attack due to limited keypad input.

• Lack of cloud integration for logging and remote monitoring.

9. Future Enhancements

• Cloud Logging: Integration with Firebase/AWS IoT for data logging and auditing.

• Biometric Authentication: Add fingerprint or face recognition for added security.

• Network Upgrade: Replace GSM with Wi-Fi/LoRa for better speed and mobile app integration.

• Tamper Detection: Sensors for physical breach or power tampering detection.

Conclusion

The system is designed to overcome the various constraints of existing locker mechanism in bank such as manpower, its inefficient service, low security level etc. The system significantly reduces the risk of unauthorized access, as well as trans- action time, with a secure combination of PIN entry, OTP verification through GSM, and a final key combination. Based on an Arduino UNO and interfaced to the SIM900A, keypad, LCD, buzzer, motor driver, this system is compact, low cost and user friendly. Its capability to instantaneously notify users on failed access attempts, and run without continuous human monitoring, makes this smart certified system an ideal choice, especially for new age banks that want to strengthen locker security through smart and trusted technology.

References

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Copyright

Copyright © 2025 Sagnik Sen, Aditi Dutta, Anirudhha Hazari, Subhankar Bhattacharjee. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.