Towards completion of the CCSDS space data link security protocol

As part of an ongoing effort in the area of space mission security, the Consultative Committee of Space Data Systems (CCSDS) created a working group to develop a Security protocol at the Data Link layer for Telecommand and Telemetry communications. While ad-hoc security implementations have been developed by several CCSDS Member Agencies, there is a recognition that a commonly engineered security protocol with minimal logical and physical integration impact on CCSDS space data link protocols and compatible with Space Link Extension (SLE) protocols would be very beneficial not only for CCSDS Member Agencies but also for commercial space missions and space data handling equipment suppliers. The results of this CCSDS working group have matured and resulted in the production of the first CCSDS Space Data Link Security (SDLS) protocol specification. This protocol provides Security Services like Authentication, Encryption and Authenticated Encryption to the existing CCSDS family of Space Data Link (SDL) protocols: Telecommand (TC), Telemetry (TM) and Advanced Orbiting Systems (AOS). Those CCSDS SDL protocols are used extensively for Telecommand as well as for both Housekeeping and Payload Telemetry space links by the entire civil space community. This paper will describe the protocol requirements, the key drivers, the protocol design description and its key concepts, the current status and open points, and the follow-on work including anticipated protocol extensions as well as the conclusions.