Efficient and Side-Channel Resistant Implementations of Next-Generation Cryptography

The rapid development of emerging information technologies, such as quantum computing and the Internet of Things (IoT), will have or have already had a huge impact on the world. These technologies can not only improve industrial productivity but they could also bring more convenience to people’s daily lives. However, these techniques have “side effects” in the world of cryptography – they pose new difficulties and challenges from theory to practice. Specifically, when quantum computing capability (i.e., logical qubits) reaches a certain level, Shor’s algorithm will be able to break almost all public-key cryptosystems currently in use. On the other hand, a great number of devices deployed in IoT environments have very constrained computing and storage resources, so the current widely-used cryptographic algorithms may not run efficiently on those devices. A new generation of cryptography has thus emerged, including Post-Quantum Cryptography (PQC), which remains secure under both classical and quantum attacks, and LightWeight Cryptography (LWC), which is tailored for resource-constrained devices. Research on next-generation cryptography is of importance and utmost urgency, and the US National Institute of Standards and Technology in particular has initiated the standardization process for PQC and LWC in 2016 and in 2018 respectively. Since next-generation cryptography is in a premature state and has developed rapidly in recent years, its theoretical security and practical deployment are not very well explored and are in significant need of evaluation. This thesis aims to look into the engineering aspects of next-generation cryptography, i.e., the problems concerning implementation efficiency (e.g., execution time and memory consumption) and security (e.g., countermeasures against timing attacks and power side-channel attacks). In more detail, we first explore efficient software implementation approaches for lattice-based PQC on constrained devices. Then, we study how to speed up isogeny-based PQC on modern high-performance processors especially by using their powerful vector units. Moreover, we research how to design sophisticated yet low-area instruction set extensions to further accelerate software implementations of LWC and long-integer-arithmetic-based PQC. Finally, to address the threats from potential power side-channel attacks, we present a concept of using special leakage-aware instructions to eliminate overwriting leakage for masked software implementations (of next-generation cryptography)

Studies of multimode fibre linked white interferometric sensor systems

This thesis undertakes a detailed analysis of both the phase and intensity noise in a multimode fibre linked white light interferometric system. Several signal processing schemes have been introduced to ease the central fringe identification and to increase the accuracy of the central position measurement. A detail investigation of modal noise induced by the multimode fibre link in the WLI system has been carried out. The relationship between modal noise and the parameters of the illuminating source and the linking optical fibre, including the coherence length of the source, the length of the linking fibre, the core diameter of the fibre and type of the fibre have been experimentally studied. A supporting theory has been developed and the results from the experiment are in good agreement with those from the theoretical analysis. Two signal processing schemes have been developed to increase the relative intensity of the central fringe of the output in a dual wavelength system. One uses an electrical circuit to square the output of the two wavelength system directly, and the other uses two detectors to detect the different wavelengths components of the output of the system. Then, these two output are multiplied and squared using an analogue electrical circuit. With the use of these signal processing schemes, the central fringe becomes more dominant. The comparison of the two signal processing schemes has also been given. A system consisting of two Michelson interferometers linked with a multimode fibre and illuminated with a dual wavelength source is investigated. The output signal to noise ratio of the system is measured by using a curve fitting method when different linking fibres are used. The result show that the output signal to noise ratio of the system increases as the core diameter of the linking fibre increases when the linking fibre is deliberately shaken. The effect of the modal noise on the central position measurement is also investigated. A signal processing scheme based on curve fitting algorithm using a cosine function is introduced for this system. The theoretical resolution of the system with the use of the signal processing scheme is given when both intensity noise and phase noise is present. The displacement measurement repeatability of the system is experimentally measured over a displacement range of 80(im. The results show that the measured repeatability (standard deviations) of the system with the use of the signal processing scheme is better than 5nm, which is very close to the value of the theoretical resolution of, 1.9nm