Cryptographic Agility: A Smooth Transition to Post-Quantum Security in the Transport Sector
Description
Cybersecurity regulations and standards are on the verge in many domains, e.g., UNECE R155 [1] in automotive, DO-326 in aviation, EU CRA & TS 50701 in the railway industry. These regulations and standards aim to prevent security breaches by mandating the implementation of cybersecurity measures. While state-of-the-art cryptographic algorithms are currently recommended, NIST guidelines recommend to avoid using RSA and ECC-based algorithms from 2035 onward [2]. Various security countermeasures rely on asymmetric cryptography, including secure flashing, secure boot, and secure access for diagnostics. Therefore, it is crucial to adopt post-quantum cryptography (PQC) to secure the relevant systems. Given that the average lifecycle of a system is typically more than 10 years in most domains (automotive, aviation, maritime, …), it is vital to begin preparing for this transition now. The shift from modern cryptographic to post-quantum cryptographic presents significant challenges, particularly in resource-constrained environments (such as Electronic Control Unit - ECU) with limited memory and computational power. Additionally, on one hand, modern cryptographic algorithms are vulnerable to quantum attacks; on the other hand, post-quantum algorithms are not yet mature enough for practical use and may be susceptible to unforeseen standard attacks. This raises the question of how to ensure an effective transition while maintaining the security of systems over their lifecycle. Cryptographic agility, which refers to a system's ability to seamlessly switch between different cryptographic algorithms and primitives, becomes an essential approach in the context of PQC. In this paper, we explore a hybrid crypto-agility solution based on a signature scheme that combines classical and post-quantum cryptography. This combination allows to address the issues of both worlds. It enables to provides resistance to standard attacks on PQC during the transition period and allows to seamlessly switch to quantum-secure PQC once the PQC schemes stood the trial of time. Additionally, this algorithm is well-suited for implementation in embedded devices, such as electronic control units (ECUs). [1] UN Regulation No. 155 - Cyber security and cyber security management system: https://unece.org/sites/default/files/2023-02/R155e%20%282%29.pdf [2] NIST, Transition to Post-Quantum Cryptography Standards: https://nvlpubs.nist.gov/nistpubs/ir/2024/NIST.IR.8547.ipd.pdf
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