Chapter 3 ("Fault Attacks In Symmetric Key Cryptosystems") is currently under submission as a survey/systemization of of knowledge paper to a peer-reviewed journal.Chapter 4 is not under submission. The contributions of the co-authors are as follows:• The write-up for the first part (Chapters 4.1, 4.2) was done by me. For the second part (Chapter 4.3), I did part of the write-up and analysis.• P. Ravi prepared the electromagnetic leakage and part of the write-up.• R. R. Shrivastwa prepared the power leakage.3 Chapter 5 is accepted as "New Insights On Differential And Linear Bounds Using Mixed Integer Linear Programming"; by A. Baksi; in International Conference on Information Technology and Communications Security (SecITC), 2020 (with major modification). This is a single-author paper by me. As such, I am responsible for everything -ideation, experimental results, write-up and proofreading and so on.