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The rapid evolution of communication technologies has ushered in an era of unprecedented interconnectedness. This hyperconnected world relies heavily on secure and private communications for critical tasks [1]. Cyber vulnerabilities in essential systems, such as those managing smart cities or automated industries, could lead to catastrophic economic and social consequences [2]. For instance, malicious intrusions into communication networks guiding autonomous vehicles could have fatal repercussions [2].

Modern warfare and crime often involve hacking activities targeting critical infrastructures (CI) [2]. These attacks aim to disrupt operations, shorten the lifespan of devices, or steal sensitive information, resulting in an estimated 2,200 known cyberattacks daily in 2022 [2]. The potential for a Cyber Apocalypse, where cyberattacks cripple a nations civilian and military services by exploiting vulnerabilities in interconnected CI systems, has become a growing concern [2].

Traditional cryptographic methods, like RSA and ECC, face a significant threat from the advent of quantum computers [3, 4]. Shors algorithm, executable on quantum computers, can solve factorization problems exponentially faster than classical algorithms, jeopardizing the security of widely used public key cryptosystems [5].

As quantum computing rapidly advances, transitioning to quantum-resistant cryptographic solutions is crucial. This urgency stems from the harvest now, decrypt later strategy, where malicious actors store encrypted data today to decrypt it once powerful quantum computers become available [6]. This threat necessitates proactive measures to ensure long-term cybersecurity, especially for systems with extended lifespans, like those found in CI [6].

Unlike information technology (IT) systems, which prioritize confidentiality, operational technology (OT) systems, often used in CI, demand high availability, with minimal downtime tolerance [7]. This difference highlights a key challenge in securing CI: any security solution should not disrupt the continuous operation of critical functions [7].

Implementing robust cybersecurity in CI faces further hurdles due to factors like legacy equipment, slow patching processes, and real-time responsiveness requirements, often necessitating millisecond-level reactions [7]. Integrating new cybersecurity measures into older CI, built without considering modern threats, presents a considerable challenge and cost compared to newer facilities designed with security in mind [8, 9].

Recent regulations requiring VPNs for insecure industrial protocols and the push for post-quantum encryption in critical infrastructure underscore the need for constant adaptation in industrial cybersecurity [10].

Post-Quantum Cryptography (PQC) offers a solution to the threat posed by quantum computers to classical cryptographic systems. PQC relies on mathematical problems that are difficult for both classical and quantum computers to solve, ensuring security in a post-quantum world [11].

There are seven main families of PQC algorithms:

Among these, lattice-based cryptography appears most promising for CI due to its relatively small key sizes and lower computational costs compared to other PQC families [13]. However, recent research proposing a polynomial-time quantum algorithm for solving the Learning with Errors (LWE) problem, which underpins many lattice-based cryptosystems, warrants caution and further investigation [14].

While not ideal for CI due to large ciphertext sizes, hash-based cryptography has seen wider adoption. SPHINCS+, a multi-time signature scheme, is being considered for standardization by Europe, Japan, and the United States [15].

Integrating PQC into CI requires careful consideration of the unique characteristics and constraints of these systems.

Latency: A primary concern is the potential latency introduced by PQC algorithms. Real-time responsiveness is paramount in OT environments, and any delays can have significant consequences [7]. Therefore, selecting and implementing PQC solutions must prioritize minimal latency to avoid operational disruptions.

Legacy Systems: Many CI rely on legacy systems with limited computational power and memory [3]. Integrating PQC into these systems without substantial hardware upgrades poses a significant challenge [4].

Flexibility and Adaptability: The PQC landscape is still evolving, with various standardization efforts globally [16]. It is crucial to implement PQC solutions with flexibility in mind, enabling adaptation to new standards and potential vulnerabilities in existing algorithms [17].

Standardization: While various countries are making efforts to standardize PQC, these efforts are primarily focused on IT systems [18]. Dedicated standardization processes for PQC implementation in industrial environments are crucial to address the specific security needs and operational constraints of CI [18].

Transitioning CI to a quantum-secure state necessitates a multi-faceted approach:

Side-Channel Attacks: Although less prevalent in OT than in IT, side-channel attacks (SCA) pose a concern for CI, particularly given the increasing sophistication of remote attack techniques [22]. Research highlights vulnerabilities in industrial control environments, emphasizing the need for robust countermeasures [23]. Addressing SCA vulnerabilities, especially in the context of PQC implementation, requires careful consideration of factors like error and fault detection, particularly in lattice-based cryptography [23].

For instance, optimizing the Number Theoretic Transform (NTT), often used in lattice-based cryptography, might inadvertently create side channels, necessitating research into secure NTT implementations [23]. Additionally, developing PQC algorithms with inherent resistance to SCA is critical for ensuring the long-term security of CI.

The development of quantum computers presents both a challenge and an opportunity for cybersecurity. While threatening current cryptographic methods, it drives the creation of more resilient solutions. The integration of PQC into CI is not merely a technical upgrade but a crucial step in ensuring the continued functionality and security of the essential services that underpin modern society. By addressing the unique challenges of this domain and prioritizing research, development, and standardization tailored for industrial environments, we can pave the way for a future where critical infrastructure remains resilient and secure in the face of evolving cyber threats.

Read the rest here:
Post-Quantum Cryptography: Safeguarding Critical Infrastructure in the Quantum Age - Medium