Encryption in ICS networks: A blessing or a curse?

Nowadays, the internal network communication of Industrial Control Systems (ICS) usually takes place in unencrypted form. This, however, seems to be bound to change in the future: as we write, encryption of network traffic is seriously being considered as a standard for future ICS. In this paper we take a critical look at the pro’s and con’s of traffic encryption in ICS. We come to the conclusion that encrypting this kind of network traffic may actually result in a reduction of the security and overall safety. As such, sensible versus non-sensible use of encryption needs to be carefully considered both in developing ICS standards and systems.