SC-3(4) - Security Function Isolation | Module Coupling and Cohesiveness

Implement security functions as largely independent modules that maximize internal cohesiveness within modules and minimize coupling between modules.


ID: SC-3(4)
Enhancement of : SC-3

Space Segment Guidance

Module coupling and cohesiveness underscore a key design principle for high-assurance space platforms: Each module should handle a focused, well-defined function without unwarranted ties to other services. If a telemetry processing unit and a cryptographic control module share minimal—and clearly documented—interfaces, an unexpected fault in one is less likely to propagate and compromise the other. Implementing strict hardware partitions or microkernels for highly critical flight software can enforce these boundaries in real time, preventing accidental data contamination across modules. Because the hardware resources and bandwidth in orbit are precious, ensuring each module is cohesive (focused on its specific task) and only lightly coupled (exchanging minimal data with other modules) promotes mission reliability and easier post-launch troubleshooting when anomalies arise.