Keys that never leave HSMs, envelope encryption with data keys, policies, grants and encryption context, versioned rotation, then cells, regions, quorum-run HSM domains and customer-held keys: three one-hour boards and the theory.
Infrastructure, platform and reliability engineers.
Your approach: Use diagrams or prose to explain responsibilities, state, capacity and failure behavior. Show the calculations requested by the question.
Design a Key Management Service like AWS KMS. Keys that never leave HSMs, envelope encryption with data keys, policies, grants and encryption context, versioned rotation, then cells, regions, quorum-run HSM domains and customer-held keys: three one-hour boards and the theory. Work from the scoping questions below. State assumptions for any unspecified load, guarantee or target, then trace your design end to end. Explain one difficult case and a credible alternative; the worked example is a reference, not a required implementation.
Resolve the scoping questions for a Key Management Service like AWS KMS. Separate stated behavior from assumptions, and identify what is outside your design.
Declare relevant volume, latency, freshness, quality or cost targets with units. Show calculations or an evaluation plan that can test them; unspecified targets are your assumptions, not hidden pass criteria.
Explain how your guarantees hold in a difficult case relevant to this subject. Address: Key types? Imported keys?
Identify users, required behavior and exclusions. Answer: Who calls? Scale?
Define the information owned by the system and the inputs, outputs and errors at its boundaries. Resolve: Latency? Custody?
Estimate the dominant workload and resource demand with units and explicit assumptions. For a learned system, also state how quality is measured and what data is available.
Draw or describe the responsibilities needed for a Key Management Service like AWS KMS. Trace a representative request, event or job from its input to a visible result; identify durable state owners.
Walk through a difficult case step by step, including detection and recovery. Consider: Data size? Key types? Imported keys?
Compare a credible alternative using your chosen workload and guarantees. Explain a remaining risk, a signal to watch and when you would change the design.