Measurable quantities in a synchronization system under attack: A first step to implement a detection system

Vulnerability of a synchronization system against different kinds of network attack is gaining a large interest in the last years. In particular, for packet-based systems like PTP, delay attacks cannot be solved by a cryptographic system, since they simply consist in the maliciously delaying timing packets in a network. However, these attacks can be detected by analysing the time series of the different quantities considered by a synchronization system. In particular, possible variations in these time series may point out the occurrence of an attack. In this paper we provide an initial overview of the main issues concerning a delay attack and then we suggest a possible solution based on a slight modification of an existing servo clock.