Secure Supervisory Control of Discrete Event Systems Using Homomorphic Encryption

This paper addresses the critical challenge of securing Cyber-Physical Systems (CPSs) against passive com- munication attacks, specifically focusing on systems modeled as Discrete Event Systems (DES). We introduce a methodology, based on the Elliptic Curve ElGamal (EC-ElGamal), to protect the confidentiality of DES-based CPS using homomorphic en- cryption. Our approach employs the computational intractabil- ity of the Elliptic Curve Discrete Logarithm Problem (ECDLP) to fortify supervisory control systems operating over vulnerable communication channels. The work details the EC-ElGamal protocol, from key generation to encryption and decryption, emphasizing its direct adaptation for ensuring robust data confidentiality within distributed DES architectures. A practical example demonstrating the application of this methodology in a DES context is implemented and tested on an ESP32 microcontroller.