Cybersecurity in critical infrastructures: a post-quantum cryptography perspective

The machinery of industrial environments was connected to the Internet years ago with the scope of increasing
\ntheir performance. However, this change made such environments
\nvulnerable against cyber-attacks that can compromise their
\ncorrect functioning resulting in economic or social problems.
\nMoreover, implementing cryptosystems in the communications between operational technology (OT) devices is a more
\nchallenging task than for information technology (IT) environments since the OT networks are generally composed of
\nlegacy elements, characterized by low-computational capabilities. Consequently, implementing cryptosystems in industrial
\ncommunication networks faces a tradeoff between the security
\nof the communications and the amortization of the industrial
\ninfrastructure. Critical infrastructure (CI) refers to the industries
\nwhich provide key resources for the daily social and economical
\ndevelopment, e.g., electricity. Furthermore, a new threat to
\ncybersecurity has arisen with the theoretical proposal of quantum
\ncomputers, due to their potential ability of breaking state-of-the-art cryptography protocols, such as RSA or elliptic curve
\ncryptography. Many global agents have become aware that
\ntransitioning their secure communications to a quantum secure
\nparadigm is a priority that should be established before the
\narrival of fault-tolerance. In this article, we aim to describe
\nthe problematic of implementing post-quantum cryptography
\n(PQC) to CI environments. For doing so, we describe the
\nrequirements for these scenarios and how they differ against
\nIT. We also introduce classical cryptography and how quantum
\ncomputers pose a threat to such security protocols. Furthermore,
\nwe introduce state-of-the-art proposals of PQC protocols and
\npresent their characteristics. We conclude by discussing the
\nproblematic of integrating PQC in industrial environments.