The machinery of industrial environments was connected to the Internet years ago with the scope of increasing their performance. However, this change made such environments vulnerable against cyber-attacks that can compromise their correct functioning resulting in economic or social problems. Moreover, implementing cryptosystems in the communications between operational technology (OT) devices is a more challenging task than for information technology (IT) environments since the OT networks are generally composed of legacy elements, characterized by low-computational capabilities. Consequently, implementing cryptosystems in industrial communication networks faces a trade-off between the security of the communications and the amortization of the industrial infrastructure. Critical Infrastructure (CI) refers to the industries which provide key resources for the daily social and economical development, e.g. electricity. Furthermore, a new threat to cybersecurity has arisen with the theoretical proposal of quantum computers, due to their potential ability of breaking state-of-the-art cryptography protocols, such as RSA or ECC. Many global agents have become aware that transitioning their secure communications to a quantum secure paradigm is a priority that should be established before the arrival of fault-tolerance. In this paper, we aim to describe the problematic of implementing post-quantum cryptography (PQC) to CI environments. For doing so, we describe the requirements for these scenarios and how they differ against IT. We also introduce classical cryptography and how quantum computers pose a threat to such security protocols. Furthermore, we introduce state-of-the-art proposals of PQC protocols and present their characteristics. We conclude by discussing the problematic of integrating PQC in industrial environments.

翻译：工业环境中的机械设备多年前便已接入互联网，旨在提升运行效率。然而，这一变革使得此类环境易受网络攻击影响，攻击可能破坏其正常功能，进而引发经济或社会问题。此外，在运营技术设备之间的通信中实施密码系统，相较于信息技术环境更具挑战性，因为运营技术网络通常由计算能力低下的老旧设备构成。因此，在工业通信网络中部署密码系统需在通信安全与工业基础设施折旧之间权衡取舍。关键基础设施指为日常社会经济发展提供关键资源（如电力）的行业。更严峻的是，量子计算机的理论构想因其可能破解RSA或ECC等现有密码协议的能力，已对网络安全构成新威胁。全球众多机构已意识到，在容错量子计算实现前，将安全通信过渡至量子安全范式是亟待确立的优先事项。本文旨在阐述在关键基础设施环境中实施后量子密码学面临的难题。为此，我们首先描述此类场景的特殊需求及其与信息技术的差异，介绍经典密码学及量子计算机对其安全协议构成的威胁，进而梳理后量子密码协议的最新方案并阐述其特征，最终探讨后量子密码学在工业环境中的集成难题。