Assess students' ability to design a Byzantine-resilient, privacy-preserving federated learning system for heterogeneous mobile edge devices. The task should require a clear system architecture and protocol specification (communication patterns, client orchestration, failure handling), design and justification of Byzantine-robust aggregation methods, implementation of cryptographic guarantees (secure aggregation primitives and differential privacy accounting with epsilon/delta and composition analysis), and strategies for device heterogeneity (stragglers, intermittent connectivity, limited resources). Students must state threat models and assumptions, provide pseudocode or protocol diagrams, complexity and security proofs/arguments, and a quantitative performance-versus-utility trade-off analysis with evaluation metrics and experimental setup.