Side Channel Security and Constant Time Questions

Covers the theory and practice of side channel vulnerabilities in cryptographic and sensitive implementations and the techniques used to prevent information leakage. Topics include types of side channel attacks such as timing attacks, power analysis, electromagnetic leakage, and microarchitectural attacks like cache and speculative execution channels. Candidates should understand how typical programming patterns leak secrets for example variable time comparisons, secret dependent array lookups, branches and loops that depend on secret values, and compiler or hardware induced variability. Mitigation techniques include writing constant time code and constant memory access patterns, masking and blinding, use of secure randomization where appropriate, atomic and branchless algorithms, and hardware or operating system level defenses. Coverage also includes practical implementation challenges and trade offs such as performance impact, correctness under compiler optimizations, testing and verification methods for leakage including unit tests and leakage detection tools, threat modeling and attacker capabilities, and real world consequences of implementation flaws. Candidates may also be evaluated on secure coding practices, code review checklists for leakage, and ability to reason about whether a given mitigation is sufficient in a given deployment.