AC-4 - Information Flow Enforcement

Enforce approved authorizations for controlling the flow of information within the system and between connected systems based on [Assignment: organization-defined information flow control policies].


Space Segment Guidance

Information-flow enforcement in spacecraft often centers on keeping command paths, housekeeping telemetry, and payload data distinct, and allowing only explicitly mediated crossings. Consider domain definitions (bus, payload, TT&C ground enclave, science processing), message labeling or partitioning that limits where data may flow, and one-way or brokered interfaces for summaries that must traverse domains (e.g., payload health to bus). Ground-to-space inputs such as plans or scripts benefit from format, range, and sequence validation before they reach flight-critical components. Fault-injection and fuzzing against CCSDS frames, APIDs, and internal protocol handlers in a twin/flatsat environment can expose unexpected paths or parser behaviors before launch.