  Critical Infrastructures (CIs) such as power grid, water and gas distribution
are controlled by Industrial Control Systems (ICS). Sensors and actuators of a
physical plant are managed by the ICS. Data and commands transmitted over the
network from the Programmable Logic Controllers (PLCs) are saved and parsed
within the Historian. Generally, this architecture guarantees to check for any
process anomalies that may occur due to component failures and cyber attacks.
The other use of this data allows activities such as forensic analysis. To
secure the network is also crucial to protect the communication between
devices. A cyber attack on the log devices could jeopardize any forensic
analysis be it for maintenance, or discovering an attack trail. In this paper
is proposed a strategy to secure plant operational data recorded in the
Historian and data exchange in the network. An integrity checking mechanism, in
combination with blockchain, is used to ensure data integrity. Data redundancy
is achieved by applying an efficient replication mechanism and enables data
recovery after an attack.
