Post-Quantum Cryptography (PQC) algorithms should remain secure even in the presence of quantum computers. Although the security of such schemes is guaranteed at the algorithmic level, real-world implementations often suffer from other vulnerabilities like Side-Channel Analysis (SCA) attacks. This Systematization of Knowledge (SoK) paper investigates SCA attacks targeting implementations of PQC algorithms. This work categorizes attacks from an adversarial perspective to identify the most vulnerable components of the algorithms' implementations and highlights unexplored parts in current implementations. In addition, it reviews and analyzes the efficiency and efficacy of existing countermeasures to SCA attacks in current hardware implementations. This approach helps identify countermeasures that provide broader protection and highlights characteristics needed for future secure implementations. Our findings offer guidance in strengthening existing systems and developing more efficient defenses against side-channel attacks.

In this paper, we deal with the deployment of Post-Quantum Cryptography (PQC) in Internet of Things (IoT). Concretely, we focus on the MQTT (Message Queuing Telemetry Transport) protocol that is widely used in IoT services. The paper presents our novel quantum-resistant security proposal for the MQTT protocol that supports secure broadcast. Our solution omits using TLS with the handshake causing delay and is suitable for sending irregular short messages. Finally, we show how our solution can practically affect concrete use cases by the performance results of the proposed solution.

This article describes an open-source quantum-resistant network traffic encryptor for the Linux platform. Our encryptor uses a combination of quantum and post-quantum key establishment methods to achieve quantum resistance combined with a fast encryption speed of AES to make quantum-resistant encryption readily available to the public. The packet-by-packet encryption architecture ensures that every bit of information is properly authenticated and encrypted. The combination of multiple key sources further increases the encryptor’s security – be it elliptic curve-based (Elliptic Curve Diffie Hellman, ECDH), quantum (Quantum Key Distribution, QKD) or post-quantum (CRYSTALS-Kyber). Without knowing all the keys obtained from different types of key sources, the final hybrid encryption key can only be obtained by brute-force means. Our contribution is very practical as the encryptor has reasonable performance, despite not being part of the Linux kernel.

With increasing digitalization and omnipresent data sensing, security and users’ privacy become essential requirements in new digital services. Group Signatures (GS) or also known as Anonymous Digital Signatures (ADS) are often used as a core Privacy-Enhancing Technology (PET) in order to keep users’ privacy during their access and/or authentication phases within ensuring the security of provided services. In this work, we provide a comprehensive assessment of group signatures on various small computing platforms typically used in modern digital services. Based on our analysis of well-established GS schemes and their libraries, we implement and evaluate chosen schemes on both well-known smartphone platforms (i.e., Android, iOS) and on a single-board computer. Our results indicate that current handheld devices can already effectively perform main group signatures’ phases and make these schemes practical for deployment in various privacy-requiring scenarios.

As quantum-safe algorithms are increasingly implemented in security protocols used in current and emerging digital services, there is also a corresponding need to map the current state of security protocols and applications and their preparedness for the post-quantum era. In this paper, we review current security recommendations, existing security libraries, and the support of Post-Quantum Cryptography (PQC) in widely-used security protocols. We also present a practical assessment of recently selected PQC algorithms by the National Institute of Standards and Technologies (NIST) PQC standardization on typical platforms that can be deployed in intelligent infrastructures (e.g., smartphones and single-boards), and recently recommended hash-based signatures for software/firmware signing. Finally, we discuss how incoming post-quantum migration affects selected areas in intelligent infrastructures.

Threshold signatures have gained increased attention especially due to their recent applications in blockchain technologies. In fact, current cryptocurrencies such as Bitcoin, and Cardano started to support multi-signature transactions. Even if the Schnorr-based threshold signatures improve the blockchain's privacy and scalability, these schemes do not provide post-quantum security. In this paper, we propose the optimization of the DS2 lattice-based $(n,n)$-threshold signature scheme and present its practical implementation. Moreover, we evaluate our optimized implementation of the DS2 scheme on different platforms. The results demonstrate that our implementation is easily portable and executable on constrained devices based on ARM Cortex-A53, ARM Cortex-M3, and ESP32 architectures.

In July 2020, the lattice-based CRYSTALS-Dilithium digital signature scheme has been chosen as one of the three third-round finalists in the post-quantum cryptography standardization process by the National Institute of Standards and Technology (NIST). In this work, we present the first Very High Speed Integrated Circuit Hardware Description Language (VHDL) implementation of the CRYSTALS-Dilithium signature scheme for Field-Programmable Gate Arrays (FPGAs). Due to our parallelization-based design requiring only low numbers of cycles, running at high frequency and using reasonable amount of hardware resources on FPGA, our implementation is able to sign 15832 messages per second and verify 10524 signatures per second. In particular, the signing algorithm requires 68461 Look-Up Tables (LUTs), 86295 Flip-Flops (FFs), and the verification algorithm takes 61738 LUTs and 34963 FFs on Virtex 7 UltraScale+ FPGAs. In this article, experimental results for each Dilithium security level are provided and our VHDL-based implementation is compared with related High-Level Synthesis (HLS)-based implementations. Our solution is ca 114 times faster (in the signing algorithm) and requires less hardware resources.