GRAIN Algorithm Implementation for Lightweight Hardware-Based OTP Authentication

This paper discusses the implementation of the GRAIN algorithm on ESP32 for hardware-based One Time Password (OTP) authentication. OTP is an authentication method that uses a random code valid for a single use and can enhance the security of authentication systems. ESP32 is a microcontroller platform that supports IoT application development and reliable wireless communication. The GRAIN algorithm was chosen for its high security and ability to generate unpredictable sequences of random numbers. OTP authentication using ESP32 can be applied to various IoT applications that require a high level of security. The implementation is done in the C language. The implementation results were tested using simulation software and ESP32 hardware to evaluate security and authentication quality. It is expected that this research will contribute to the development of authentication technology for IoT systems and other applications that require a high level of security. The conclusion of this research is the proposed OTP authentication hardware system is able to decrypts encrypted OTPs sent by an authenticator to an RFID card, using the ESP32 as a constrained device equipped with an OLED screen and a button. Furthermore, the authenticator generates ciphered OTPs based on GRAIN 128 and sends them to the hardware via an MQTT gateway, utilizing only 25 percent of available resources, making it suitable for constrained devices.