Information is extracted not by reading files or decrypting frames but by observing physical or protocol byproducts of computation, power draw, electromagnetic emissions, timing, thermal signatures, or traffic patterns. Repeated measurements create distinctive fingerprints correlated with internal states (key use, table loads, parser branches, buffer occupancy). Matching those fingerprints to models or templates yields sensitive facts without direct access to the protected data. In space systems, vantage points span proximity assets (for EM/thermal), ground testing and ATLO (for direct probing), compromised on-board modules that can sample rails or sensors, and remote observation of link-layer timing behaviors.
| 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 | ||||
| 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 | ||||
| CM0003 | TEMPEST / EMSEC | TEMPEST controls (i.e., emissions security (EMSEC)) protect spacecraft system components, internal data communications, and communication buses against side-channel and proximity-based attacks that exploit unintended electromagnetic, electrical, or acoustic emanations. Critical components must be enclosed within appropriate casings or shielding structures that attenuate unintended emissions to levels that deny adversaries the ability to reconstruct processed data or infer system state from externally observable signals. Shielding must extend to internal buses and data pathways, not only to individual processing elements, as inter-component communications represent a significant and often overlooked emanations surface. The physical enclosure strategy must be integrated with the broader system architecture so that shielding effectiveness is not degraded by penetrations, connectors, or cable routing that create unintended emissions paths. During sustainment & maintenance, Spacecraft TEMPEST and EMSEC protections are primarily established during design, fabrication, and integration, but sustainment remains applicable through configuration control, review of deployment-state or hardware changes, preservation of qualification evidence, assessment of relevant anomalies, and evaluation of refurbishment, replacement, or follow-on production changes. The guidance below addresses these spacecraft considerations as well as applicable ground-segment maintenance activities. | PE-19 PE-19(1) PE-21 SC-8(3) | A.7.5 A.7.8 A.8.12 | ||||
| CM0050 | On-board Message Encryption | Authentication controls on the spacecraft internal bus verify the identity of communicating components but do not protect the confidentiality of the data in transit; an adversary with access to the bus, whether through a compromised component, a hardware implant, or a physical access event, can observe all unencrypted inter-component communications regardless of whether authentication is enforced. Encrypting data traversing the spacecraft internal bus protects the confidentiality of selected message content from entities that can observe the bus but do not possess authorization and the applicable cryptographic keys. The protection does not prevent disclosure to a compromised component that legitimately possesses the decryption key, and it may not conceal unencrypted protocol headers, addressing information, message timing, or traffic volume. Bus encryption should be considered for bus segments or message types carrying information whose unauthorized disclosure would create unacceptable mission, security, privacy, or operational risk. Criticality alone does not establish a confidentiality requirement. Where confidentiality is required, encryption must be combined with message integrity, source authentication, and replay protection through an approved authenticated-encryption mechanism or an appropriately composed set of cryptographic protections. | AC-4 AC-4(23) AC-4(24) AC-4(26) AC-4(31) AC-4(32) PL-8 PL-8(1) SA-3 SA-8 SA-8(18) SA-8(19) SA-8(9) SA-9(6) SC-13 SC-16 SC-16(1) SC-16(2) SC-16(3) SC-8(1) SC-8(3) SI-19(4) SI-4(10) SI-4(25) | A.5.14 A.8.22 A.8.23 A.8.11 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 A.8.26 A.5.31 A.8.11 | ||||
| CM0062 | Dummy Process - Aggregator Node | In spacecraft architectures containing aggregator or relay nodes, observable computation and communication patterns may reveal valid aggregation cycles and traffic-flow relationships involving critical nodes, root nodes, or ground termination points. This countermeasure is applicable when the threat model identifies a credible adversary capability to observe node power or electromagnetic activity and correlate those observations with RF transmission activity. While camouflaging all network traffic through constant high-power transmission is energy-prohibitive, selectively obscuring aggregator node behavior through dummy process execution provides a practical alternative. This countermeasure requires aggregator nodes to execute dummy workloads whose observable characteristics are sufficiently similar to genuine aggregation cycles to make reliable classification difficult within the mission-defined adversary model. Evaluation should consider applicable power, electromagnetic, execution-duration, processor-activity, memory-access, and RF-correlated features rather than matching only an average power-consumption curve. Two properties are essential for effectiveness: first, dummy processes must vary in their execution pattern, using a different dummy process each time or maintaining a low repetition rate, to prevent adversaries from identifying a distinguishable signature that differentiates dummy from genuine execution; second, timing of dummy execution must be carefully controlled, with a dummy process executed every time the aggregator receives a transmission and randomly during idle periods, to prevent adversaries from correlating the presence or absence of radio frequency (RF) transmissions with power consumption curves to identify and discard dummy activity. Together, these properties are intended to reduce an observer’s ability to distinguish valid aggregation cycles and infer traffic flow toward a critical root or base-station node. They do not guarantee that aggregator nodes, network topology, or the base station cannot be identified through other observations. | PE-19 PE-19(1) | A.7.5 A.7.8 A.8.12 | ||||
| CM0057 | Tamper Resistant Body | A tamper-resistant physical enclosure increases the effort, time, and equipment required to physically probe, observe, remove, or modify protected spacecraft sensor nodes and embedded components. The enclosure must be designed for the specific physical-access and side-channel threats being addressed and should not be assumed to prevent every invasive or non-invasive attack. A passive tamper-resistant body can provide physical and side-channel protection without continuous processing or electrical power, which may make it suitable for resource-constrained sensor nodes. The design trade must also account for mass, volume, thermal performance, manufacturability, inspection, repairability, qualification, and lifecycle cost. Enclosures incorporating active sensing or response mechanisms require power and must be evaluated separately from fully passive designs. The physical security design must distinguish among tamper resistance, which impedes access; tamper evidence, which leaves observable indications of attempted access; tamper detection, which senses an attempt while it occurs; and tamper response, which protects designated sensitive assets after detection. The required properties and response behavior must be selected according to the protected component, threat model, and mission consequence of both successful tampering and false activation. | PE-19 PE-19(1) PL-8 PL-8(1) SA-3 SA-4(5) SA-4(9) SA-8 SC-51 | A.7.5 A.7.8 A.8.12 A.5.8 A.5.2 A.5.8 A.8.25 A.8.31 A.8.27 A.8.28 | ||||
| CM0058 | Power Randomization | Power randomization is a hardware-level countermeasure against power analysis side-channel attacks, in which an adversary monitors a device's power consumption during cryptographic or other security-sensitive operations to extract secret information such as cryptographic keys by correlating power traces with internal computational states. The technique uses an on-chip hardware mechanism to add data-independent or randomized power activity intended to reduce the observable signal-to-noise ratio between measured power consumption and security-sensitive internal computations. Power randomization increases the number or sophistication of measurements required for power analysis but does not eliminate the underlying leakage or guarantee resistance against averaging, profiling, multi-trace, or higher-order analysis. Power randomization must be incorporated into the chip architecture or selected as an existing capability of the target device. Its implementation can increase dynamic power consumption, die area, thermal load, design and verification complexity, non-recurring engineering cost, and potentially unit fabrication cost. Resulting spacecraft-level mass or volume impacts depend on packaging, power-delivery, and thermal-management consequences. These tradeoffs must be evaluated during the system design phase against the mission's threat model and the availability of alternative or complementary side-channel countermeasures, with power randomization selected where the protection it provides justifies its SWaP and cost impact. | PE-19 PE-19(1) | A.7.5 A.7.8 A.8.12 | ||||
| CM0059 | Power Consumption Obfuscation | Power consumption obfuscation encompasses hardware circuit design techniques and architectural obfuscation strategies that mask the relationship between a device's internal operations and its observable power consumption profile, increasing the difficulty and cost of power analysis side-channel attacks. Unlike power randomization, which adds noise to the power signal, obfuscation techniques actively obscure the underlying power consumption pattern through circuit-level design approaches such as dual-rail logic, balanced circuit topologies, and constant-power execution paths that decouple observable power draw from data-dependent computational activity. These techniques increase manufacturing cost and design complexity for sensor nodes and other embedded hardware, representing a one-time investment at fabrication that must be justified against the mission's physical threat environment and the sensitivity of the data processed by the protected device. Power consumption obfuscation is most effectively applied to hardware executing cryptographic operations or other security-sensitive functions where correlation between power traces and internal state would be most damaging if successfully exploited. | PE-19 PE-19(1) | A.7.5 A.7.8 A.8.12 | ||||
| CM0060 | Secret Shares | Secret sharing for side-channel protection, commonly implemented as masking, represents each sensitive value or intermediate computation using multiple randomized shares. A masking scheme of order dtypically uses d+1 shares and is designed so that observation of up to dshares or covered intermediate values does not reveal information about the underlying sensitive value within the defined security model. The complete set of shares reconstructs the original value and therefore must not be considered mutually independent. Computation must be performed on the shares using masking operations or gadgets designed to preserve the required security order. Masking can prevent straightforward first-order exploitation and increase the observations or attack complexity required to recover the secret, but joint leakage from multiple shares, unintended recombination, register transitions, glitches, memory activity, or other implementation effects may remain exploitable. Higher-order attacks specifically attempt to combine leakage associated with multiple shares and are not eliminated merely by dividing a value into shares. The primary operational tradeoff is a significant increase in computational operations, approaching a doubling of the number of operations required, which translates directly into increased power consumption; this overhead must be evaluated carefully against the spacecraft's power budget and the processing constraints of the target hardware. Masking should be applied to the complete set of operations, intermediate values, key schedules, conversions, memory transfers, and control paths whose leakage could disclose the protected secret. Selective masking may be used when analysis demonstrates that unmasked operations and transitions do not expose secret-dependent information and that the resulting implementation remains secure within the approved leakage model. | PE-19 PE-19(1) | A.7.5 A.7.8 A.8.12 | ||||
| CM0061 | Power Masking | Power masking is a side-channel countermeasure in which secret-dependent values and intermediate computations are represented using multiple randomized shares. A masking scheme of order d is designed so that observations involving up to dcovered intermediate values do not reveal information about the protected secret under the scheme’s defined leakage and adversary model. Correctly implemented masking can prevent straightforward lower-order exploitation and increase the complexity or number of observations required for successful power or electromagnetic analysis. It does not guarantee protection regardless of the number of measurements: higher-order, profiled, multivariate, or implementation-specific attacks may combine leakage from multiple shares or observations and recover the protected secret. The masking scheme generates randomized shares and performs the protected computation using masking operations designed to preserve the required security order. Reconstruction or conversion to an unmasked representation must occur only at an explicitly authorized boundary and must not expose secret-dependent values through registers, memory, buses, transitions, glitches, control flow, or other observable implementation state. Power masking applies secret-sharing principles to the secret key, cryptographic state, and other secret-dependent intermediate values throughout a computation. CM0060 may describe the general share-based protection concept, while CM0061 should focus on implementing and preserving that sharing across cryptographic operations to reduce exploitable power and electromagnetic leakage. Effective masking requires correct implementation across the entire cryptographic execution path, as a single unmasked intermediate value anywhere in the computation can restore exploitable correlation and defeat the protection. | PE-19 PE-19(1) | A.7.5 A.7.8 A.8.12 | ||||
| CM0063 | Increase Clock Cycles/Timing | Timing side-channel attacks exploit observable differences in execution time to infer information about secret values, such as cryptographic keys, by correlating measured execution durations with data-dependent branching paths or memory access patterns. This countermeasure reduces timing leakage by ensuring that execution time, control flow, instruction selection, and memory-access behavior do not vary as a function of secret values within the defined implementation and threat model. Additional computation or delay may be used where appropriate, but constant-time behavior should primarily be achieved by eliminating secret-dependent branches, memory accesses, and variable-latency operations. Memory accesses involving secret-dependent values or indices shall be implemented so that observable access patterns and timing do not vary as a function of the protected secret within the defined threat model. Non-secret-dependent memory accesses need not be normalized solely for this countermeasure. Where mission timing requirements permit, access time normalization can be achieved by adding deliberate delays to faster accesses to equalize timing across all operations. Constant-time implementation may increase execution time, code size, memory use, power consumption, or design complexity, depending on the algorithm, implementation technique, processor, and memory architecture. These impacts must be measured for the target platform and evaluated against timing, power, thermal, and throughput mission requirements. | PE-19 PE-19(1) | A.7.5 A.7.8 A.8.12 | ||||
| CM0064 | Dual Layer Protection | Dual-layer physical enclosure protection reduces thermal side-channel leakage by combining an inner heat-spreading layer with an outer thermally insulating barrier. The design is intended to attenuate the spatial and temporal relationship between internal computational activity and externally observable surface-temperature patterns; it must not be assumed to make thermal activity completely unobservable. Thermal side-channel attacks observe temperature or infrared-emission patterns associated with device activity to infer information such as workload, active functional regions, execution behavior, or, under applicable adversary and measurement conditions, security-sensitive computation. The inner conductive layer spreads heat laterally to reduce localized temperature gradients and shorten the persistence of internal hot spots. Residual gradients and transient patterns may remain because of component placement, enclosure geometry, interface conductance, workload, and the available heat-rejection path. The outer thermally insulating layer limits direct access to the inner heat-spreading surface and attenuates the propagation of short-duration temperature gradients to the observable exterior. The external surface may still exhibit temperature or infrared-emission variations that must be evaluated against the mission-defined adversary capability. This countermeasure can operate passively without direct computational or electrical-power consumption. However, it can impose mass, volume, thermal-resistance, heat-rejection, structural, integration, and qualification impacts and may indirectly increase demand on active thermal-control systems. Its suitability must therefore be evaluated against both security and spacecraft thermal-design requirements. | PE-19 PE-19(1) | A.7.5 A.7.8 A.8.12 | ||||
| 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 | ||||