Some missions field secondary links, separate frequencies and hardware, for limited, purpose-built functions (e.g., rekeying, emergency commanding, beacons, custodial crosslinks). Adversaries co-opt these channels as covert data paths: embedding content in maintenance messages, beacon fields, or low-rate housekeeping; initiating vendor/service modes that carry file fragments; or switching to contingency profiles that bypass normal routing and monitoring. Because these paths are distinct from the main TT&C and may be sparsely supervised, they provide discreet avenues to move data off the spacecraft or to external relays without altering the primary link’s traffic patterns.
| ID | Name | Tiering | Description | NIST Rev5 | ISO 27001 | Onboard SV | Ground | |
| CM0002 | COMSEC | Communications security (COMSEC) denies unauthorized parties access to information derived from telecommunications while ensuring the authenticity of those communications. COMSEC is commonly defined as a broad discipline that may encompass cryptographic security, transmission security, emissions security, cryptographic key management, traffic-flow security, and physical security of COMSEC material. Within SPARTA, these areas are further broken down through separate countermeasures, including CM0029 | TRANSEC, CM0030 | Crypto Key Management, CM0003 | TEMPEST/EMSEC, and CM0073 | Traffic Flow Analysis Defense. CM0002 provides the overarching communications-security context and supports the coordinated application of these specialized countermeasures. All mission links, particularly telemetry, tracking, and commanding (TT&C) links, should employ communications-security protections appropriate to the sensitivity, criticality, operational environment, and threat exposure of the information being exchanged. These protections may include cryptographic protection, transmission security, emissions security, traffic-flow protection, secure key management, and physical protection of COMSEC material, as addressed by the applicable specialized countermeasures. Spacecraft should not provide an operational mode that permits required cryptographic protection or command authentication on TT&C links to be bypassed or disabled. Operational, maintenance, test, recovery, and contingency modes should be considered when evaluating whether communications-security protections can be unintentionally or improperly circumvented. Communication receivers and associated signal-processing or TRANSEC mechanisms should detect and, when mission-defined criteria are met, reject or otherwise safely handle transmissions exhibiting anomalous signal characteristics consistent with communications deception. Cryptographic mechanisms should authenticate and integrity-check received content but should not be treated as RF-deception detectors. | AC-17 AC-17(1) AC-17(10) AC-17(2) AC-18 AC-18(1) AC-2(11) AC-3(10) CA-3 IA-4(9) IA-5 IA-5(7) IA-7 PL-8 PL-8(1) SA-8(18) SA-8(19) SA-9(6) SC-10 SC-12 SC-12(1) SC-12(2) SC-12(3) SC-12(6) SC-13 SC-16(3) SC-28(1) SC-28(3) SC-7 SC-7(10) SC-7(11) SC-7(18) SC-7(5) SC-8(1) SC-8(3) SI-10 SI-10(3) SI-10(5) SI-10(6) SI-19(4) SI-3(8) | A.5.14 A.6.7 A.8.1 A.8.16 A.5.14 A.8.1 A.8.20 A.5.14 A.8.21 A.5.16 A.5.17 A.5.8 A.5.14 A.8.16 A.8.20 A.8.22 A.8.23 A.8.26 A.8.12 A.5.33 A.8.20 A.8.24 A.8.24 A.8.26 A.5.31 A.5.33 A.8.11 | ||||
| CM0030 | Crypto Key Management | Effective cryptographic key management is a foundational requirement for all mission encryption and authentication functions; the security of cryptographic implementations is only as strong as the protection afforded to the keys those implementations rely upon. Key management must conform to recognized cryptographic guidance and address the full lifecycle applicable to each key type, including generation or establishment, distribution, storage, activation, use, replacement, deactivation or revocation, recovery where authorized, compromise response, and destruction. Only approved cryptographic algorithms, key generation methods, key distribution techniques, and authentication mechanisms may be used; the use of unapproved, deprecated, or custom cryptographic primitives is prohibited regardless of perceived functional adequacy. Encryption key handling must be performed outside of onboard software and protected through dedicated cryptographic mechanisms, preventing keys from being exposed through software vulnerabilities, memory inspection, or software-level debugging interfaces. Secret and private key material must not be retrievable in plaintext through telecommands, telemetry, diagnostic outputs, debugging interfaces, or other externally accessible mechanisms, regardless of the privilege level of the requesting entity. | CM-3(6) PL-8 PL-8(1) SA-3 SA-4(5) SA-8 SA-9(6) SC-12 SC-12(1) SC-12(2) SC-12(3) SC-12(6) SC-28(3) SC-8(1) | A.5.8 A.5.2 A.5.8 A.8.25 A.8.31 A.8.27 A.8.28 A.5.33 A.8.24 | ||||
| CM0031 | Authentication | All command-bearing sessions, frames, or messages involving spacecraft command links, crosslinks, or relay services shall provide cryptographic authentication of the command origin and integrity verification before commands are accepted. Mutual or bidirectional authentication shall be required where both endpoints must authenticate one another and the link and protocol architecture support that exchange. Acquisition requirements should mandate cryptographically based, bidirectional authentication for all command sessions across external links, including ground-to-spacecraft uplinks, spacecraft-to-spacecraft crosslinks, and any relay or intermediary ground station connections, with authentication required aBidirectional authentication enables both communicating entities to verify each other’s identity and helps prevent impersonation. Authentication establishes identity but does not by itself authorize a command, protect mission-data confidentiality, or prevent session hijacking. Command acceptance must also enforce authorization, and authenticated sessions or security associations must maintain integrity and replay resistance so that subsequent traffic remains bound to the authenticated entities. Beyond external links, authentication is strongly recommended for spacecraft internal bus communications and onboard inter-component connections, as an adversary with access to internal interfaces, whether through a compromised component or a physical access event, should face the same authentication barrier as an external adversary attempting to inject commands from outside the spacecraft. | AC-14 AC-17 AC-17(10) AC-17(2) AC-18 AC-18(1) IA-2 IA-3(1) IA-4 IA-4(9) IA-7 IA-9 PL-8 PL-8(1) SA-3 SA-4(5) SA-8 SA-8(15) SA-8(9) SC-16 SC-16(1) SC-16(2) SC-32(1) SC-7(11) SC-8(1) SI-14(3) SI-7(6) | A.5.14 A.6.7 A.8.1 A.5.14 A.8.1 A.8.20 A.5.16 A.5.16 A.5.8 A.5.2 A.5.8 A.8.25 A.8.31 A.8.27 A.8.28 A.5.33 | ||||
| CM0073 | Traffic Flow Analysis Defense | Traffic flow analysis attacks enable adversaries to derive operationally significant intelligence from observable transmission characteristics, including message timing, volume, duration, periodicity, and routing information, without decrypting the content of communications. Even when link encryption is in place, unprotected traffic patterns can reveal spacecraft operational schedules, command activity, contact windows with specific ground stations, and anomalous events that provide adversaries with actionable mission intelligence. Traffic flow analysis defense encompasses a set of techniques applied to protect the confidentiality of transmission metadata on telemetry, tracking, and commanding (TT&C) and data links, as well as onboard communications where applicable. Applicable techniques include padding transmissions to normalize message lengths and volumes, introducing artificial traffic during idle periods to obscure true contact patterns and event timing, obfuscating routing information and endpoint identities, varying transmission periodicity to defeat statistical pattern recognition, and frustrating traffic volume and duration analysis through active obfuscation methods. These controls are a complement to, but distinct from, cryptographic content protection, and should be applied based on a threat-informed assessment of the value of traffic metadata to potential adversaries and their collection capabilities. | SC-8 SI-4(15) | A.5.10 A.5.14 A.8.20 A.8.26 | ||||
| CM0036 | Session Termination | Where session-oriented communications are used between ground systems and spacecraft, between ground system components, or across internal spacecraft interfaces, the associated connection or session must be terminated upon completion or after a period of inactivity exceeding a threshold defined in the mission’s concept of operations (CONOPS). Failure to terminate idle or completed sessions leaves authenticated connections open and exploitable, providing adversaries with an opportunity to inject commands or data into an existing authenticated session without needing to complete the authentication process independently. Inactivity timeout thresholds must be established through the CONOPS process rather than set arbitrarily, balancing the security benefit of rapid session termination against the operational consequences of terminating a session that an operator or automated process may legitimately require across a contact gap or processing delay. Session termination must invalidate the associated session identifiers, authorization state, and cryptographic session state so that the terminated session cannot be reused. Where secure session resumption is operationally required, it must use a mission-approved, cryptographically protected mechanism with defined validity limits and must not permit reuse of expired, revoked, or invalidated session state. | AC-12 AC-12(2) SC-10 SI-14(3) SI-4(7) | A.8.20 | ||||
| CM0071 | Communication Physical Medium | The physical medium selected for ground segment networking directly affects the mission's vulnerability to passive interception, traffic flow analysis, and electromagnetic eavesdropping, making medium selection a security design decision that must be informed by the mission's threat model. Fiber optic cabling transmits data optically and does not produce the same conducted or radiated electrical emanations as copper cabling, reducing exposure to proximity-based electromagnetic collection. Fiber may still be intercepted through physical access, optical coupling, compromised patch points, or endpoint equipment, and medium selection alone does not conceal traffic timing or volume from an observer with access to the link or its endpoints. Fiber should therefore be considered where the threat model identifies electromagnetic emanation or physical-medium interception risk, while cryptographic and physical protections remain applicable, particularly for links carrying mission-sensitive data such as command uplink traffic, cryptographic key material, or mission planning data. The selection of physical medium should be treated as a threat-informed engineering decision evaluated for each network segment based on the sensitivity of the data carried, the physical accessibility of the cabling, and the threat environment of the facility in which the cabling is installed. | PE-4 SC-8 SC-8(1) SC-8(3) SC-8(5) | A.7.2 A.7.12 A.5.10 A.5.14 A.8.20 A.8.26 A.5.33 | ||||
| CM0029 | TRANSEC | Transmission security (TRANSEC) is the component of communications security (COMSEC) concerned with protecting the characteristics of the transmission itself, as distinct from protecting the content of the information being communicated. TRANSEC controls reduce the likelihood, effectiveness, or operational impact of transmission interception, signal disruption, communications deception, and exploitation of transmission characteristics within the defined threat model. Applicable TRANSEC techniques include jam-resistant waveforms that increase resistance to jamming and communications deception, spread spectrum and frequency hopping techniques that reduce signal predictability and improve resistance to interception and disruption, low probability of intercept and low probability of detection (LPI/LPD) signal designs that reduce transmission observability, and transmission scheduling or pattern discipline that limits the intelligence value of traffic analysis. TRANSEC requirements should be applied to mission communication links according to link criticality (e.g., TT&C, crosslinks), threat exposure, and operational consequence. TRANSEC must be treated as a distinct layer of protection complementary to, but not a substitute for, cryptographic protection of information content. | AC-17 AC-18 AC-18(5) CA-3 CP-8 PL-8 PL-8(1) SA-8(19) SC-16 SC-16(1) SC-40 SC-40(1) SC-40(3) SC-40(4) SC-5 SC-8(1) SC-8(3) SC-8(4) | A.5.14 A.6.7 A.8.1 A.5.14 A.8.1 A.8.20 A.5.14 A.8.21 A.5.29 A.7.11 A.5.8 A.5.33 | ||||