# Integrating Elliptic Curve Cryptography with the Modbus TCP SCADA Communication Protocol
## 1 Introduction  
_Supervisory Control and Data Acquisition_ or _SCADA_ systems are industrial, automated, supervision infrastructures based on information technologies which are embedded in industrial installations as well as production lines to ascertain continuous correct operation, enforce quality control and raise alarms in case of malfunctions or efforts of malicious interference. In general, interconnected SCADA system components are installed in critical parts of industrial infrastructures, such as electricity grids, power generation stations, and nuclear power reactors, in order to detect malfunctions and raise alerts for remedial actions. Most importantly, for increased versatility and real time alerting capabilities as well as remote control purposes, during the last decades SCADA systems are installed so as to be connected to the _Internet_ and the _Internet of Things_ (_IoT_). This versatility, however, comes at the cost of exposing SCADA systems and supervised infrastructures to all the cybersecurity threats that beset the Internet. Thus, today, SCADA systems are vulnerable to attacks such as, among several others, interception of data traffic, malicious modifications of settings and control operations data, malicious modification of measurements and infrastructure data and Denial-of-Service attacks. Numerous SCADA system failures have been recorded because of a targeted attack or a non-targeted (i.e., incidental) malware infection [1]. Except for accidental SCADAsystem infections by viruses their target was simple computers, there are also cases of targeted attacks with software made specifically for SCADA. Such attacks are more recent and are mainly aimed at impacting the physical world while, in parallel, they may also target industrial espionage. The first such attack is in 2009, targeting several companies (Shell, BP, Exxon). The virus that attacks these systems is Night Dragon, which belongs to the category Remote Access Trojans [2]. His purpose was data theft and espionage through e-mail theft. Then we have one of the most notorious targeted SCADA attacks which attracted the attention of the security and safety research communities and organizations and sparked the alert in SCADA system security. This attack was launched in 2010 by a virus named Stuxnet and was aimed at an enriched uranium nuclear facility in Iran. The purpose of Stuxnet was to intercept and modify data that was read from or written to PLCs (Programmable Logic Controller- the heart of SCADA systems). In addition, Stuxnet aimed at impairing the nuclear facility and cause devastating damage and, even, human life losses. The result was the destruction of, almost, 1/5 of the nuclear centrifuges. After this incident, the interest in securing SCADA systems, and not only the supervised (by SCADA) physical establishment, increased considerably. In the years that followed, more malware nodules resembling Stuxnet appeared (e.g., Flame and Duqu) [3], some of which even using portions of Stuxnet's code. After the incidents discussed above (and several others) as well as the high cyberattack costs for the targeted organization, the SCADA research community is engaged in strengthening SCADA systems with cryptographic methods and cryptographic protection mechanisms with emphasis on data and messaging encrypted protection and device identification and authentication. However, the limited computation capabilities of many SCADA sensors and embedded devices as well as the Internet/IoT connectivity, SCADA systems are vulnerable to numerous attacks [4]. Modbus is a data communications protocol for use with its PLCs (Programmable Logic Controllers) and has become as a standard communication protocol. It is commonly used and widespread of connecting industrial devices, such as IoTs and applications. It supports communication among multiple devices connected to a network. Modbus places few restrictions on the format of the data to be transmitted and the data use character via communication lines.