Method for generating a cryptographically strong keystream using a lightweight stream cipher

Abstract

The invention relates to the field of cryptography and information security, in particular to methods of lightweight stream encryption and hashing adapted for operation under conditions of limited computing resources, such as microcontrollers as part of the Internet of Things. Description of the invention: The invention relates to cryptography and information security, specifically to a method for generating a cryptographically secure key stream using a lightweight stream cipher for microcontrollers in IoT systems. The ESP32-based device receives biometric data from a MAX30102 sensor (pulse, oxygen), which is broken into 32-bit blocks. The internal state is initialized either using a constant or based on unique device parameters. Next, bitwise logical processing is performed, adaptive byte swapping (based on temperature or power supply), and the addition of a noise component from a random number generator. After processing, a 96-bit hash value is generated, which is signed by the ESP32's built-in cryptographic accelerator. The signed hash is transmitted via the BLE interface to an external server, where the authenticity and integrity of the data are verified. This method is effective in resource-constrained environments.