A hardware assisted implementation of Time Varying Encryption System

Security on Internet communications has become an essential value in most of the modern IT infrastructures. An increasing number of organizations are improving their security mechanisms, looking for better protection against cyber attacks. Particularly, security has a principal role on the deployment and design of embedded and distributed systems as Cyber-Physical Systems (CPS) for the Industrial Internet of Things (IIoT).In this paper we present a simple solution to improve the security in Ethernet communications based on time transfer capabilities available in CPS. A hardware assisted implementation of a Time Varying Encryption System (TVES) has been developed, in which the current time is used as an input for a periodic time dependant key generation, making more difficult to access the transmitted or received data. Using the currently widely adopted Precision Time Protocol (PTP) for time distribution with hardware assisted timestamping, a sub-microsecond synchronization level has been achieved. This accuracy level allows a time varying encrypted communication scheme between master and slave based on a shared time reference.In our experiments, a symmetric-key scheme is used, but the method is fully compatible with asymmetric-keys scenarios. Due to the time dependancy of the keys, in case of a malicious access to the retrieved data, a brute-force decryption will not be useful because of the wide range of generated keys and their refresh rate. This range will result on an external perception of a random encryption.