Satellite communication data security encryption transmission method and system and storage medium

Abstract

The invention is suitable for the technical field of satellite communication, and provides a satellite communication data security encryption transmission method and system and a storage medium, and the method comprises the steps: obtaining satellite solar azimuth data in real time, calculating a solar elevation angle, and judging a day and night state; collecting daytime ground albedo or nighttime city light data according to the data; extracting characteristic values from the data to generate encryption factors, and generating session key encryption data in combination with satellite instantaneous orbit parameters; and ground station latitudes are sorted according to day and night states, and differentiated key distribution paths are planned. According to the invention, dynamic encryption and security key transmission are realized, and the security of satellite communication data is improved.

Description

Technical Field

[0001] This invention belongs to the field of satellite communication technology, and in particular relates to a method, system and storage medium for secure encrypted transmission of satellite communication data. Background Technology

[0002] With the rapid development of technologies such as low-Earth orbit satellite constellations and high-throughput satellites, satellite communication has been widely applied in navigation and positioning, remote sensing monitoring, emergency communication, and global internet access, with data transmission scale and real-time requirements continuously increasing. Due to the wide coverage and open transmission environment of satellite communication links, data security has become a core requirement for satellite communication systems. Encrypted transmission technology, as a key means of resisting data leakage and tampering, has become a key focus of industry research and development in terms of security, dynamic adaptability, and transmission reliability. Currently, satellite communication encryption technologies mainly revolve around three core aspects: key generation, key distribution, and data encryption. However, existing solutions generally suffer from insufficient adaptability to the dynamic operating environment of satellites, making it difficult to fully address the security needs of scenarios such as satellite transit over different areas and day-night cycles.

[0003] In existing technologies, satellite communication data encryption often employs fixed session keys or periodically updated key mechanisms. The key generation process often relies on static information such as fixed satellite identifiers and preset algorithm parameters. Key distribution path planning is mostly based on the geographical distance of ground stations, preset priorities, or fixed topologies, without dynamically adjusting to the differences in the link environment during satellite operation. In the encryption factor extraction stage, the real-time environmental physical characteristics of the satellite coverage area are rarely utilized, and the algorithm relies more on random numbers or fixed parameters generated internally, lacking a strong correlation with the dynamic satellite scenario. Summary of the Invention

[0004] The purpose of this invention is to provide a secure encrypted transmission method for satellite communication data, aiming to solve the technical problems existing in the prior art as identified in the background section.

[0005] This invention is implemented as follows: a method for secure encrypted transmission of satellite communication data, the method comprising: The system acquires real-time solar azimuth angle data from satellites and automatically determines whether the satellite is currently in daytime or nighttime mode by calculating the solar altitude angle, generating a unified day / night mode determination result. Based on the day / night status determination results, corresponding environmental optical data are collected, including: when it is determined to be daytime, ground albedo distribution data are collected; when it is determined to be nighttime, urban light distribution data are collected. Encryption factors are generated based on environmental optical data: when it is determined to be daytime, albedo feature values ​​are extracted from ground albedo distribution data as encryption factors; when it is determined to be daytime, light feature values ​​are extracted from urban light distribution data as encryption factors, and satellite communication data is encrypted based on the encryption factors. Based on the same day and night state determination results, the latitude data of the ground stations are obtained and sorted, and key distribution paths are planned for daytime and nighttime according to the latitude sorting results of the ground stations.

[0006] As a further aspect of the present invention, the generation of a unified day-night state determination result specifically includes: Real-time acquisition of solar azimuth data, which includes measurements of both elevation and azimuth components; Based on the elevation angle component in the solar azimuth angle data, combined with satellite orbit parameters and UTC time, the solar elevation angle value is calculated; The zero-degree threshold is set as the angle between the sun's rays and the ground plane. The solar altitude angle value is compared with the zero-degree threshold. If the solar altitude angle is greater than zero degrees, the day-night state determination result is generated. If the solar altitude angle is less than or equal to zero degrees, the night-night state determination result is generated.

[0007] As a further embodiment of the present invention, the acquisition of corresponding environmental optical data specifically includes: Based on the day / night status determination results, when it is determined to be daytime, the land area currently covered by the satellite is scanned to obtain surface reflectance data including visible light and near-infrared bands; The surface reflectance data is preprocessed to generate standardized ground albedo distribution data, which is stored in a grid format, with each grid cell containing an albedo value. When it is determined to be nighttime, the satellite takes pictures of the urban area currently covered by the satellite to obtain data on the nighttime light intensity of the urban area; Nighttime light intensity data is preprocessed to generate standardized urban light distribution data, which is stored in a grid format, with each grid cell containing light brightness values.

[0008] As a further aspect of the present invention, the generation of encryption factors based on environmental optical data specifically includes: When it is determined to be daytime, feature extraction is performed on the ground albedo distribution data to identify continuous areas with albedo greater than 0.3, and the geometric center coordinates, contour shape parameters and average albedo values ​​of the continuous areas are calculated and combined to generate albedo feature values. When it is determined to be nighttime, feature extraction is performed on the urban light distribution data to identify bright spot areas with brightness values ​​greater than 10dB of the background noise threshold. The geographic coordinate set, brightness distribution gradient, and spatial arrangement characteristics of the bright spot areas are calculated and combined to generate light feature values. Based on the albedo and light characteristics, the session key for this satellite communication is generated; The session key is used to encrypt satellite communication data in real time, and the data stream is encrypted block by block using a block cipher mode.

[0009] As a further aspect of the present invention, the generation of the session key for this satellite communication specifically includes: Extract the latitude and longitude fractions of all coordinate values ​​from the set of geometric center coordinates contained in the albedo feature values ​​and the set of geographic location coordinates contained in the light feature values, and convert the latitude and longitude fractions into fixed-length binary strings; The binary strings are arranged according to their original order in the feature value list. Strings with odd numbers and strings with even numbers are assigned to two sets respectively. The binary sequences of the two sets are then cross-merged to form the initial binary sequence. The initial binary sequence is cyclically shifted with the binary representation of the instantaneous latitude value of the satellite's current orbit, and the final binary sequence obtained after the operation is defined as the session key for this satellite communication.

[0010] As a further aspect of the present invention, the planning of the key distribution path specifically includes: Based on the day / night status determination results, access the pre-stored ground station database to obtain the latitude data of all available ground stations; The latitude data of all available ground stations are sorted to generate a sequence of ground stations arranged from low to high latitude values; When it is determined to be daytime, ground stations are selected sequentially from low latitude to high latitude according to the ground station sequence to establish a key distribution path; When it is determined to be nighttime, ground stations are selected sequentially from high latitude to low latitude according to the ground station sequence to establish a key distribution path; The key materials and synchronization parameters required for the encrypted session are transmitted through the established key distribution path.

[0011] Another object of the present invention is to provide a secure encrypted transmission system for satellite communication data, the system comprising: The day / night status determination module is used to acquire the satellite's solar azimuth angle data in real time, and automatically determine whether the satellite is currently in day or night status by calculating the solar altitude angle, generating a unified day / night status determination result; The environmental optical data acquisition module is used to collect corresponding environmental optical data based on the day / night status determination results, including: collecting ground albedo distribution data when it is determined to be daytime; and collecting urban light distribution data when it is determined to be nighttime. The encryption factor generation module is used to generate encryption factors based on environmental optical data: when it is determined to be daytime, it extracts albedo feature values ​​from ground albedo distribution data as encryption factors; when it is determined to be daytime, it extracts light feature values ​​from urban light distribution data as encryption factors, and encrypts satellite communication data according to the encryption factors. The key distribution path planning module is used to obtain and sort the latitude data of the ground stations based on the same day and night status determination results, and plan key distribution paths for daytime and nighttime respectively according to the latitude sorting results of the ground stations.

[0012] As a further embodiment of the present invention, the encryption factor generation module includes: The albedo feature extraction unit is used to extract features from the ground albedo distribution data when it is determined to be daytime, identify continuous areas with albedo greater than 0.3, calculate the geometric center coordinates, contour shape parameters and average albedo values ​​of the continuous areas, and combine them to generate albedo feature values. The light feature extraction unit is used to extract features from the urban light distribution data when it is determined to be nighttime, identify bright spot areas with brightness values ​​greater than 10dB of the background noise threshold, calculate the geographic coordinate set, brightness distribution gradient and spatial arrangement features of the bright spot areas, and combine them to generate light feature values. The session key generation unit is used to generate the session key for this satellite communication based on the albedo feature value and the light feature value. The satellite communication data encryption unit is used to encrypt satellite communication data in real time using the session key, and to encrypt the data stream block by block using a block cipher working mode.

[0013] As a further embodiment of the present invention, the key distribution path planning module includes: The ground station latitude sorting unit is used to sort the latitude data of all available ground stations and generate a sequence of ground stations arranged from low to high latitude values. The daytime key distribution path planning unit is used to select ground stations sequentially from low latitude to high latitude according to the ground station sequence when it is determined to be daytime to establish a key distribution path. The nighttime key distribution path planning unit is used to select ground stations sequentially from high latitude to low latitude according to the ground station sequence when it is determined to be nighttime to establish a key distribution path. The key transmission unit is used to transmit the key materials and synchronization parameters required for the encrypted session through the established key distribution path.

[0014] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the satellite communication data secure encryption transmission method.

[0015] The beneficial effects of this invention are: This invention effectively solves the security and adaptability problems of existing technologies by constructing a full-process encryption system that includes day / night scene determination, scene-based optical data acquisition, dynamic encryption factor generation, and differentiated key path planning. Based on real-time determination of the satellite's day / night status using the solar elevation angle, a unified scene benchmark is provided for subsequent steps, ensuring deep adaptation of encryption operations to the satellite's dynamic coverage environment. Scene-based optical data such as daytime ground albedo and nighttime city lights are collected, and multi-dimensional feature values ​​are extracted as encryption factors. These are combined with the satellite's instantaneous orbital parameters to generate session keys, achieving "one-time key" encryption and avoiding the security risks of fixed keys. Furthermore, the encryption factors integrate environmental physical characteristics and satellite dynamic parameters, significantly enhancing randomness and uniqueness, and greatly improving anti-cracking capabilities. Differentiated key distribution paths are planned based on day / night status, adapting to the advantages of different time-of-day link environments, reducing the impact of link interference on key transmission, and ensuring the transmission stability of key materials and synchronization parameters. Synchronous transmission of key materials and synchronization parameters ensures precise matching of the encryption rhythm between the ground station and the satellite, avoiding decryption misalignment. Overall, this achieves full-process secure encryption of satellite communication data from generation to transmission, fully adapting to the high-speed dynamic operation characteristics of satellites and balancing security and reliability. Attached Figure Description

[0016] Figure 1 A flowchart of a satellite communication data secure encryption transmission method provided in an embodiment of the present invention; Figure 2 A flowchart for generating a unified day / night state determination result provided for embodiments of the present invention; Figure 3 A flowchart for collecting corresponding environmental optical data provided in an embodiment of the present invention; Figure 4 A flowchart for generating encryption factors based on environmental optical data provided in an embodiment of the present invention; Figure 5 A flowchart for planning the key distribution path provided in an embodiment of the present invention; Figure 6 A structural block diagram of a satellite communication data secure encryption transmission system provided in an embodiment of the present invention; Figure 7 This is a structural block diagram of the encryption factor generation module provided in an embodiment of the present invention; Figure 8This is a structural block diagram of the key distribution path planning module provided in an embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] Figure 1 A flowchart of a satellite communication data secure encryption transmission method provided in an embodiment of the present invention is shown below. Figure 1 As shown, the method includes: S100 acquires the solar azimuth angle data of the satellite in real time, and automatically determines whether the satellite is currently in daytime or nighttime state by calculating the solar altitude angle, generating a unified day and night state determination result; The solar azimuth angle is chosen as the core input because the satellite is always in a dynamic spatial position during its orbital operation. The altitude component of the solar azimuth angle can directly reflect the light intensity and illumination status of the area currently covered by the satellite. This is the most reliable physical basis for distinguishing between day and night scenes, rather than relying on subjective time division or fixed regional rules. This avoids the deviation in day and night determination caused by different latitudes and seasons when the satellite passes over the area.

[0019] When calculating the solar altitude angle, the altitude component of the solar azimuth angle needs to be combined with satellite orbit parameters and UTC time. The satellite orbit parameters are used to accurately locate the current space observation point (nadir point) of the satellite, ensuring that the calculation can be accurately associated with the geographic coordinates of the ground coverage area. UTC time provides a globally unified time reference, eliminating the interference of different time zone differences on the calculation of solar declination (the latitude of the subsolar point that varies with the date) and solar hour angle (reflecting the angle difference between local solar time and noon), further ensuring the accuracy of the solar altitude angle value.

[0020] Subsequently, a solar altitude angle of 0 degrees was used as the threshold for judgment. The setting of this threshold revolves around the effectiveness of subsequent optical data acquisition: when the solar altitude angle is greater than 0 degrees, the satellite coverage area can receive direct or diffuse sunlight, and the ground albedo data has clear optical characteristics, which can provide sufficient signals for the extraction of encryption factors; when the solar altitude angle is less than or equal to 0 degrees, the area is in a low light or no light state, and urban lights become the main optical signal source. At this time, it is easier to obtain bright spot features that can be used to generate encryption factors when collecting light data. This threshold directly realizes the accurate connection between day and night scenes and subsequent encryption data sources.

[0021] like Figure 2 As shown, the generation of a unified day / night state determination result specifically includes: S110, real-time acquisition of solar azimuth data, which includes measured values ​​of two dimensions: altitude angle component and azimuth angle component; S120, Based on the altitude angle component in the solar azimuth angle data, combined with satellite orbit parameters and UTC time, calculate the solar altitude angle value: sin(α)=sin(φ)*sin(δ)+cos(φ)*cos(δ)*cos(H); in: α is the solar altitude angle. This is the target angle that needs to be calculated, referring to the angle between the sunlight and the local ground plane.

[0022] φ represents the geographical latitude of the observation point. That is, the geographical latitude of the satellite's nadir point (the point where the satellite is projected vertically onto the Earth's surface).

[0023] δ represents the solar declination. It refers to the latitude of the point where the sun's rays are directly overhead on Earth, and its value varies with the date.

[0024] H represents the solar hour angle. It is an astronomical angle that expresses time, specifically the angular difference between the local solar time at the sub-satellite point and the solar noon.

[0025] S130, set the angle between the sun's rays and the ground plane to 0 degrees as the zero-degree threshold, compare the solar altitude angle value with the zero-degree threshold, if the solar altitude angle is greater than zero degrees, generate the day-night state determination result for the daytime, and if the solar altitude angle is less than or equal to zero degrees, generate the nighttime day-night state determination result.

[0026] S200 collects corresponding environmental optical data based on the day / night status determination results, including: when it is determined to be daytime, collecting ground albedo distribution data; when it is determined to be nighttime, collecting urban light distribution data. During the daytime, the satellite-covered area is affected by sunlight, and different ground features exhibit varying reflectivity. Collecting ground albedo distribution data is chosen because this type of data can capture the unique optical characteristics of ground features through the differences in reflectivity between the visible and near-infrared bands. The visible light band reflects differences in the color and brightness of ground features, while the near-infrared band enhances the distinction between vegetation and non-vegetation, and between wet and dry surfaces. Combining these two approaches ensures that the collected data possesses rich feature dimensions, sufficient to support the subsequent extraction of encryption factors. At night, when sunlight disappears, ground albedo data loses its distinctiveness due to weak signals. At this time, city lights become the main stable optical signal source. Collecting city light distribution data can not only avoid noise interference in the low light environment at night, but also take advantage of the clustering and gradient distribution characteristics of city lights to obtain characteristic data with unique features.

[0027] In the specific data acquisition and processing process, during the daytime, the land area currently covered by the satellite needs to be scanned to exclude areas such as the ocean with relatively uniform albedo and lack of characteristic differences, so as to reduce the interference of invalid data on subsequent processing and ensure that the collected surface reflectance data is focused on land areas that can provide rich features. The reflectance data is then preprocessed to generate gridded ground albedo distribution data. The purpose of the gridded design is to transform continuous surface reflectance information into structured data units. Each grid corresponds to the albedo value of a fixed geographical area. This format facilitates the rapid location of continuous areas with high albedo and ensures spatial accuracy during feature extraction, avoiding feature value deviations caused by data chaos.

[0028] Nighttime data collection focuses on urban areas covered by satellites. After capturing nighttime light intensity data, gridded urban light distribution data is generated through preprocessing. The key point of this preprocessing is to remove noise signals from non-urban lights, such as starlight and atmospheric scattering, to ensure that the brightness values ​​within the grid truly reflect the distribution of artificial light sources, providing a clean data foundation for subsequent identification of bright spots and extraction of light features.

[0029] like Figure 3 As shown, the acquisition of corresponding environmental optical data specifically includes: S210, based on the day / night status determination result, when it is determined to be daytime, scans the land area currently covered by the satellite to obtain surface reflectance data including visible light and near-infrared bands; S220, preprocess the surface reflectance data to generate standardized ground albedo distribution data, which is stored in grid form, with each grid cell containing an albedo value; S230: When it is determined to be nighttime, the satellite takes pictures of the urban area currently covered by the satellite to obtain nighttime light intensity data of the urban area; S240, preprocess the nighttime light intensity data to generate standardized urban light distribution data, which is stored in a grid format, with each grid cell containing light brightness values.

[0030] Extraction of daytime albedo features: Region identification: The gridded ground albedo distribution data is scanned to identify connected regions formed by all pixels with an albedo value greater than 0.3. This threshold is intended to filter out ground features with significant albedo characteristics, such as clouds, snow cover, and deserts.

[0031] Geometric center coordinates: For each identified continuous region, calculate the average of the geographic coordinates (latitude and longitude) of all its pixels to obtain the center point of the region.

[0032] Contour shape parameters: Extract the boundary contour of the region and calculate its shape descriptor: perimeter, area, and compactness (perimeter² / area).

[0033] Average albedo value: The arithmetic mean of the albedo values ​​of all pixels in the region is taken to obtain a value representing the overall brightness.

[0034] Feature combination: The center coordinates, shape parameters and average albedo of the multiple regions calculated above are arranged in descending order of region area and encoded into a structured data sequence, namely albedo feature value.

[0035] Nighttime light feature extraction: Bright spot detection: Brightness threshold segmentation is applied to urban light distribution data to identify all pixel areas whose brightness values ​​exceed the background noise level by 10dB. This effectively filters out weak noise and focuses on areas where artificial light sources are concentrated.

[0036] Geographic coordinate set: Records the set of geographic coordinates (latitude and longitude) of all pixels within each identified bright spot area.

[0037] Brightness distribution gradient: Analyze the rate of change of brightness of each bright spot from the center to the edge, and calculate its radial brightness gradient to describe the "sharpness" and "diffuseness" of the bright spot.

[0038] Spatial arrangement characteristics: Analyze the spatial distribution pattern of all bright spots, calculate the average distance and directional distribution of nearest neighbor bright spots (whether they are linear or mesh-like), and use the spatial autocorrelation index to quantify their aggregation degree.

[0039] Feature combination: The coordinate set, gradient information and overall spatial arrangement pattern of the main bright spot group (the first N brightest bright spots) are encoded into a structured data sequence, namely the light feature value.

[0040] S300 generates encryption factors based on environmental optical data: when it is determined to be daytime, it extracts albedo feature values ​​from ground albedo distribution data as encryption factors; when it is determined to be daytime, it extracts light feature values ​​from urban light distribution data as encryption factors, and encrypts satellite communication data based on the encryption factors. In daytime scenarios, when extracting features from ground albedo distribution data, the system selects continuous areas with an albedo greater than 0.3 as targets. This threshold accurately filters out features with significant optical differences, such as clouds, snow cover, and deserts. The albedo of these features is much higher than that of conventional features like vegetation and farmland. The geometric shape and albedo values ​​of their continuous areas are highly scene-specific and will not repeat at different times or in different areas. Subsequently, the system calculates the geometric center coordinates, contour shape parameters, and average albedo values ​​of the continuous areas. This multi-dimensional information combination increases the complexity of the encryption factor: single coordinates or albedo values ​​are easy to predict, but when combined with contour shape parameters, each feature value becomes a composite information body of coordinates + shape + value, significantly reducing the probability of repetition.

[0041] In nighttime scenarios, bright spots with brightness values ​​exceeding the background noise threshold by 10 dB are extracted from urban light distribution data. The core objective is to filter out invalid noise such as starlight and atmospheric scattering in low-light environments, focusing on stable signals from artificial light sources. The distribution, brightness gradient (the rate of brightness decay from the center to the edge of the bright spot), and spatial arrangement of urban light spots exhibit distinct regional characteristics and dynamically change with urban schedules and regional functions. This dynamism naturally endows light feature values ​​with a unique, one-time-one-scene attribute. Calculating the geographic coordinate set, brightness distribution gradient, and spatial arrangement characteristics of bright spot areas also involves superimposing multi-dimensional information to ensure that the encryption factors generated at night, like the daytime albedo feature values, possess an unrepeatable scene imprint.

[0042] In the session key generation stage, the decimal part of latitude and longitude is extracted and converted into a fixed-length binary string. The decimal part contains more precise location information, providing richer bit data and avoiding information redundancy or loss due to insufficient precision in the integer part. The fixed length design ensures the uniformity of subsequent key formats and adapts to the encryption requirements of block ciphers. The binary string is separated and cross-merged according to parity numbers, increasing the randomness of the key by shuffling the original sequence. If arranged in the original order, attackers may be able to reverse the sequence through coordinate patterns, but after cross-merging, the sequence logic is reconstructed, significantly increasing the difficulty of cracking. Then, it is cyclically shifted with the binary value of the instantaneous latitude of the satellite's current orbit. When the satellite is operating in low Earth orbit, the instantaneous latitude changes in real time with its orbital position, and the instantaneous latitude is different for each communication. The cyclic shift operation allows the final key to simultaneously integrate environmental optical features and satellite dynamic position features, forming a dual dynamic guarantee and completely realizing one-time key.

[0043] Finally, the block cipher mode is adopted to encrypt the data stream block by block, which is adapted to the real-time and reliability requirements of satellite communication: satellite communication data is mostly transmitted in a streaming manner, and block-by-block encryption does not require waiting for the complete data block, which can reduce transmission latency; in the block mode, the encryption of each data block is performed independently, so even if an anomaly occurs in the transmission of a certain data block, it will not affect the decryption of other data blocks. At the same time, the standardized encryption process of the block cipher can ensure encryption efficiency and avoid overloading the satellite's computing power due to complex algorithms.

[0044] like Figure 4 As shown, the generation of encryption factors based on environmental optical data specifically includes: S310, when it is determined to be daytime, feature extraction is performed on the ground albedo distribution data, continuous areas with albedo greater than 0.3 are identified, the geometric center coordinates, contour shape parameters and average albedo values ​​of the continuous areas are calculated, and albedo feature values ​​are generated by combining them. S320, when it is determined to be nighttime, feature extraction is performed on the urban light distribution data to identify bright spot areas with brightness values ​​greater than 10dB of the background noise threshold, and the geographic coordinate set, brightness distribution gradient and spatial arrangement characteristics of the bright spot areas are calculated and combined to generate light feature values. S330 generates the session key for this satellite communication based on the albedo and light characteristics. S340, the session key is used to encrypt satellite communication data in real time, and the data stream is encrypted block by block using a block cipher working mode.

[0045] In this step, generating the session key for this satellite communication specifically includes: Extract the latitude and longitude fractions of all coordinate values ​​from the set of geometric center coordinates contained in the albedo feature values ​​and the set of geographic location coordinates contained in the light feature values, and convert the latitude and longitude fractions into fixed-length binary strings; The binary strings are arranged according to their original order in the feature value list. Strings with odd numbers and strings with even numbers are assigned to two sets respectively. The binary sequences of the two sets are then cross-merged to form the initial binary sequence. The initial binary sequence is cyclically shifted with the binary representation of the instantaneous latitude value of the satellite's current orbit, and the final binary sequence obtained after the operation is defined as the session key for this satellite communication.

[0046] Example 1: Daytime Key Generation Based on Albedo Features The following three high-albedo regions were extracted from their center coordinates (decimal parts) using albedo eigenvalues: Region 1: Longitude -87.6234°, Latitude 46.7812° → Round to decimal (.6234, .7812) Region 2: Longitude -88.1357°, Latitude 45.9236° → Round to decimal (.1357, .9236) Region 3: Longitude -86.9741°, Latitude 47.2358° → Round to decimal (.9741, .2358) Convert the fractional part to 8 bits: .6234→10011110, .7812→11000100 .1357→00100001, .9236→11101100 .9741→11111010, .2358→00111011 Separate by parity number: Odd number array: [10011110,11000100,11111010,00111011] Even array: [00100001, 11101100] Cross-merging forms the initial sequence: 100111100010000111000100111011001111101000111011 The satellite's current instantaneous latitude is 42.3567°. This is converted to binary 01010100. After shifting the binary sequence 5 bits to the right, a right XOR operation is performed with the initial sequence to obtain the final 128-bit session key.

[0047] Example 2: Nighttime Key Generation Based on Urban Lighting Features The coordinates of the following three main bright spot regions were extracted: Bright spot area 1: Longitude 139.7368°, Latitude 35.6524° → rounded down to (.7368, .6524) Bright spot area 2: Longitude 139.5812°, Latitude 35.4237° → rounded down to (.5812, .4237) Bright spot area 3: Longitude 139.6943°, Latitude 35.5179° → rounded down to (.6943, .5179) Binary conversion: .7368→10111100, .6524→10100110 .5812→10010100, .4237→01101100 .6943→10110001, .5179→10000100 Weighted sorting (by brightness weight): Bright spot region 1 (weight 0.4) → Bright spot region 2 (weight 0.35) → Bright spot region 3 (weight 0.25) Arrange the items in weighted order and then perform modulo operation: (10111100+10100110)mod251=202→11001010 (10100110+10010100)mod251=185→10111001 (10010100+01101100)mod251=175→10101111 After concatenation, the key is circularly shifted left by 3 bits to the UTC timestamp 023507 (milliseconds) to generate the final session key.

[0048] S400, based on the same day and night state determination results, obtains and sorts the latitude data of the ground station, and plans key distribution paths for daytime and nighttime according to the latitude sorting results of the ground station.

[0049] The satellite operates in a high-speed orbit, and the time a low-orbit satellite spends passing over a ground station is usually only a few minutes. The pre-stored database has pre-screened and stored basic information of ground stations with normal communication capabilities, which can quickly locate effective transmission nodes and avoid missing the key transmission window due to excessive time spent on real-time search, thus ensuring the timeliness of key transmission from a time perspective.

[0050] Sort the available ground stations by latitude from low to high in order to establish a unified basic sequence: latitude, as a fixed geographical attribute of the ground station, does not fluctuate with the real-time environment. Using this as the sorting benchmark can avoid the path planning logic disorder caused by chaotic sorting standards, and at the same time provide a clear direction for subsequent path adjustments in day and night scenarios, reducing the computational complexity of the system.

[0051] In terms of path selection logic, ground stations are selected in order from low latitude to high latitude during the day. The core reason is to adapt to the characteristics of the daytime link environment: During the day, low latitude regions are affected by solar radiation, atmospheric convection is relatively stable, and ionospheric activity is relatively mild. The communication link between the ground station and the satellite is less likely to be affected by signal attenuation, phase distortion, and other interferences, and key transmission is less likely to result in data loss or tampering. At the same time, the daytime illumination in low latitude regions is stable, and the receiving equipment of the ground station is less affected by extreme weather, which can ensure the integrity of the transmission of key materials and synchronization parameters.

[0052] Selecting ground stations in order from high latitude to low latitude at night is an optimization for the nighttime link environment: atmospheric noise is significantly reduced in high-latitude regions at night, interference from city lights to optical receiving equipment is greatly reduced, the link signal-to-noise ratio is higher, and the risk of key transmission being intercepted or cracked is lower; in addition, ionospheric disturbances are weaker in high-latitude regions at night, which can reduce link signal fluctuations and ensure accurate transmission of synchronization parameters. Synchronization parameters are the key to matching the encryption rhythm between the ground station and the satellite. Once the synchronization is off, even if the key is obtained, it cannot be decrypted correctly.

[0053] Finally, the key materials and synchronization parameters are transmitted through the planned path. This step is designed to achieve the dual goals of secure key delivery and synchronized decryption logic.

[0054] like Figure 5 As shown, the planned key distribution path specifically includes: S410, based on the day / night status determination result, accesses the pre-stored ground station database to obtain the latitude data of all available ground stations; S420 sorts the latitude data of all available ground stations to generate a sequence of ground stations arranged from low to high latitude values. S430, when it is determined to be daytime, select ground stations in the order from low latitude to high latitude according to the ground station sequence to establish a key distribution path; S440, When it is determined to be nighttime, select ground stations in the order from high latitude to low latitude according to the ground station sequence to establish a key distribution path; S450 transmits the key materials and synchronization parameters required for the encrypted session through the established key distribution path.

[0055] Example 3: Daytime Low-Latitude Path Selection and Dynamic Switching Assuming the satellite passes overhead during the day, the available ground stations and their latitude distribution are as follows: Regional Station 1: Latitude 10.5° Regional Station 2: Latitude 15.3° Regional Station 3: Latitude 35.2° Regional Station 4: Latitude 50.1° The system generates a sequence sorted by latitude: [Region 1 station, Region 2 station, Region 3 station, Region 4 station] According to the daytime strategy, the system prioritizes establishing the master key distribution channel at Station 1 in Region 1, with Station 2 in Region 2 serving as a hot backup channel. When the signal-to-noise ratio at Station 1 drops below the 8dB threshold due to deteriorating weather conditions, the system automatically switches to Station 2 in Region 150ms to continue key distribution, ensuring continuous and reliable key transmission.

[0056] Example 4: Redundancy Backup Mechanism for High-Latitude Nighttime Paths When a satellite passes overhead at night, ground stations can be deployed: Area 5 stations: Latitude 5.2° Regional 6 stations: Latitude 20.8° 7 stations in the region: latitude 55.3° 8 stations in the region: latitude 62.1° 9 stations in the region: latitude 65.4° After sorting by latitude, the system executes a nighttime high-latitude priority strategy: Main path: Area 9 station → Area 8 station (redundant backup) The system continuously monitors the link status of each station. When the bit error rate of station 9 in region exceeds the threshold of 10^-5 due to space weather disturbances, the key distribution traffic is automatically switched to station 8 in region while maintaining the monitoring connection of station 9 in region. The dual-path distribution mode is restored after the environmental conditions improve.

[0057] Example 5: Seamless path switching during day-night transition The satellite operates during the day-night transition period, and the system re-determines the day-night status every 30 seconds. The initial status is daytime, and a low-latitude path is selected. Ten stations in the region (latitude 12.3°) serve as the main stations. 11 stations in the region (latitude 18.7°) serve as backup stations. When a satellite enters a shadowed area, the system determines that the status has changed to night and immediately performs a path switch: Close the key distribution channels at Area 10 and Area 11 stations. High-latitude path activated: Regional station 12 (latitude 58.6°) → Regional station 13 (latitude 63.9°) During the handover process, the system ensures the continuity of key distribution through on-board buffering, and the entire handover is completed within 500ms, achieving a seamless transition for the ground receiver. The system also establishes redundant links between Area 12 and Area 13 stations to ensure high reliability of key distribution at night.

[0058] Figure 6 A structural block diagram of a satellite communication data secure encryption transmission system provided in an embodiment of the present invention is shown below. Figure 6 As shown, the system includes: The day / night status determination module 100 is used to acquire the satellite's solar azimuth angle data in real time, automatically determine whether the satellite is currently in day or night status by calculating the solar altitude angle, and generate a unified day / night status determination result. The environmental optical data acquisition module 200 is used to acquire corresponding environmental optical data based on the day / night state determination results, including: acquiring ground albedo distribution data when it is determined to be daytime; and acquiring urban light distribution data when it is determined to be nighttime. The encryption factor generation module 300 is used to generate encryption factors based on environmental optical data: when it is determined to be daytime, it extracts albedo feature values ​​from ground albedo distribution data as encryption factors; when it is determined to be daytime, it extracts light feature values ​​from urban light distribution data as encryption factors, and encrypts satellite communication data according to the encryption factors. The key distribution path planning module 400 is used to obtain and sort the latitude data of the ground station based on the same day and night status determination results, and plan key distribution paths for daytime and nighttime respectively according to the latitude sorting results of the ground station.

[0059] like Figure 7 As shown, the encryption factor generation module 300 includes: Albedo feature extraction unit 310 is used to extract features from the ground albedo distribution data when it is determined to be daytime, identify continuous areas with albedo greater than 0.3, calculate the geometric center coordinates, contour shape parameters and average albedo values ​​of the continuous areas, and combine them to generate albedo feature values. The light feature extraction unit 320 is used to extract features from the urban light distribution data when it is determined to be nighttime, identify bright spot areas with brightness values ​​greater than the background noise threshold of 10dB, calculate the geographic coordinate set, brightness distribution gradient and spatial arrangement features of the bright spot areas, and combine them to generate light feature values. The session key generation unit 330 is used to generate the session key for this satellite communication based on the albedo feature value and the light feature value; The satellite communication data encryption unit 340 is used to encrypt satellite communication data in real time using the session key and to encrypt the data stream block by block using a block cipher working mode.

[0060] like Figure 8 As shown, the key distribution path planning module 400 includes: Ground station latitude sorting unit 410 is used to sort the latitude data of all available ground stations and generate a ground station sequence arranged from low to high latitude values. The daytime key distribution path planning unit 420 is used to select ground stations sequentially from low latitude to high latitude according to the ground station sequence when it is determined to be daytime to establish a key distribution path. The nighttime key distribution path planning unit 430 is used to select ground stations sequentially from high latitude to low latitude according to the ground station sequence when it is determined to be nighttime to establish a key distribution path. The key transmission unit 440 is used to transmit the key materials and synchronization parameters required for the encrypted session through the established key distribution path.

[0061] Furthermore, a computer-readable storage medium stores a computer program that, when executed by a processor, causes the processor to perform the steps of the satellite communication data secure encryption transmission method described above.

[0062] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for secure encrypted transmission of satellite communication data, characterized in that, The method includes: The system acquires real-time solar azimuth angle data from satellites and automatically determines whether the satellite is currently in daytime or nighttime mode by calculating the solar altitude angle, generating a unified day / night mode determination result. Based on the day / night status determination results, corresponding environmental optical data are collected, including: when it is determined to be daytime, ground albedo distribution data are collected; when it is determined to be nighttime, urban light distribution data are collected. Encryption factors are generated based on environmental optical data: when it is determined to be daytime, albedo feature values ​​are extracted from ground albedo distribution data as encryption factors; when it is determined to be daytime, light feature values ​​are extracted from urban light distribution data as encryption factors, and satellite communication data is encrypted based on the encryption factors. Based on the same day and night state determination results, the latitude data of the ground stations are obtained and sorted, and key distribution paths are planned for daytime and nighttime according to the latitude sorting results of the ground stations.

2. The method according to claim 1, characterized in that, The generation of a unified day / night state determination result specifically includes: Real-time acquisition of solar azimuth data, which includes measurements of two dimensions: elevation angle component and azimuth angle component; Based on the elevation angle component in the solar azimuth angle data, combined with satellite orbit parameters and UTC time, the solar elevation angle value is calculated; The zero-degree threshold is set as the angle between the sun's rays and the ground plane. The solar altitude angle value is compared with the zero-degree threshold. If the solar altitude angle is greater than zero degrees, the day-night state determination result is generated. If the solar altitude angle is less than or equal to zero degrees, the night-night state determination result is generated.

3. The method according to claim 2, characterized in that, The collected environmental optical data specifically includes: Based on the day / night status determination results, when it is determined to be daytime, the land area currently covered by the satellite is scanned to obtain surface reflectance data including visible light and near-infrared bands; The surface reflectance data is preprocessed to generate standardized ground albedo distribution data, which is stored in a grid format, with each grid cell containing an albedo value. When it is determined to be nighttime, the satellite takes pictures of the urban area currently covered by the satellite to obtain data on the nighttime light intensity of the urban area; Nighttime light intensity data is preprocessed to generate standardized urban light distribution data, which is stored in a grid format, with each grid cell containing light brightness values.

4. The method according to claim 3, characterized in that, The generation of encryption factors based on environmental optical data specifically includes: When it is determined to be daytime, feature extraction is performed on the ground albedo distribution data to identify continuous areas with albedo greater than 0.3, and the geometric center coordinates, contour shape parameters and average albedo values ​​of the continuous areas are calculated and combined to generate albedo feature values. When it is determined to be nighttime, feature extraction is performed on the urban light distribution data to identify bright spot areas with brightness values ​​greater than 10dB of the background noise threshold. The geographic coordinate set, brightness distribution gradient, and spatial arrangement characteristics of the bright spot areas are calculated and combined to generate light feature values. Based on the albedo and light characteristics, the session key for this satellite communication is generated; The session key is used to encrypt satellite communication data in real time, and the data stream is encrypted block by block using a block cipher mode.

5. The method according to claim 4, characterized in that, The generation of the session key for this satellite communication specifically includes: Extract the latitude and longitude fractions of all coordinate values ​​from the set of geometric center coordinates contained in the albedo feature values ​​and the set of geographic location coordinates contained in the light feature values, and convert the latitude and longitude fractions into fixed-length binary strings; The binary strings are arranged according to their original order in the feature value list. Strings with odd numbers and strings with even numbers are assigned to two sets respectively. The binary sequences of the two sets are then cross-merged to form the initial binary sequence. The initial binary sequence is cyclically shifted with the binary representation of the instantaneous latitude value of the satellite's current orbit, and the final binary sequence obtained after the operation is defined as the session key for this satellite communication.

6. The method according to claim 4, characterized in that, The planned key distribution path specifically includes: Based on the day / night status determination results, access the pre-stored ground station database to obtain the latitude data of all available ground stations; The latitude data of all available ground stations are sorted to generate a sequence of ground stations arranged from low to high latitude values; When it is determined to be daytime, ground stations are selected sequentially from low latitude to high latitude according to the ground station sequence to establish a key distribution path; When it is determined to be nighttime, ground stations are selected sequentially from high latitude to low latitude according to the ground station sequence to establish a key distribution path; The key materials and synchronization parameters required for the encrypted session are transmitted through the established key distribution path.

7. A satellite communication data secure encryption transmission system, characterized in that, The system includes: The day / night status determination module is used to acquire the satellite's solar azimuth angle data in real time, and automatically determine whether the satellite is currently in day or night status by calculating the solar altitude angle, generating a unified day / night status determination result; The environmental optical data acquisition module is used to collect corresponding environmental optical data based on the day / night status determination results, including: collecting ground albedo distribution data when it is determined to be daytime; and collecting urban light distribution data when it is determined to be nighttime. The encryption factor generation module is used to generate encryption factors based on environmental optical data: when it is determined to be daytime, it extracts albedo feature values ​​from ground albedo distribution data as encryption factors; when it is determined to be daytime, it extracts light feature values ​​from urban light distribution data as encryption factors, and encrypts satellite communication data according to the encryption factors. The key distribution path planning module is used to obtain and sort the latitude data of the ground stations based on the same day and night status determination results, and plan key distribution paths for daytime and nighttime respectively according to the latitude sorting results of the ground stations.

8. The system according to claim 7, characterized in that, The encryption factor generation module includes: The albedo feature extraction unit is used to extract features from the ground albedo distribution data when it is determined to be daytime, identify continuous areas with albedo greater than 0.3, calculate the geometric center coordinates, contour shape parameters and average albedo values ​​of the continuous areas, and combine them to generate albedo feature values. The light feature extraction unit is used to extract features from the urban light distribution data when it is determined to be nighttime, identify bright spot areas with brightness values ​​greater than 10dB of the background noise threshold, calculate the geographic coordinate set, brightness distribution gradient and spatial arrangement features of the bright spot areas, and combine them to generate light feature values. The session key generation unit is used to generate the session key for this satellite communication based on the albedo feature value and the light feature value. The satellite communication data encryption unit is used to encrypt satellite communication data in real time using the session key, and to encrypt the data stream block by block using a block cipher working mode.

9. The system according to claim 8, characterized in that, The key distribution path planning module includes: The ground station latitude sorting unit is used to sort the latitude data of all available ground stations and generate a sequence of ground stations arranged from low to high latitude values. The daytime key distribution path planning unit is used to select ground stations sequentially from low latitude to high latitude according to the ground station sequence when it is determined to be daytime to establish a key distribution path. The nighttime key distribution path planning unit is used to select ground stations sequentially from high latitude to low latitude according to the ground station sequence when it is determined to be nighttime to establish a key distribution path. The key transmission unit is used to transmit the key materials and synchronization parameters required for the encrypted session through the established key distribution path.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, causes the processor to perform the steps of the satellite communication data secure encryption transmission method according to any one of claims 1 to 6.

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