WO2025234814A1 - Method and apparatus for improving authentication of satellite communication - Google Patents

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. An operation method of a user equipment (UE) in a wireless communication system, according to an embodiment of the present disclosure, may comprise the steps of: receiving a first message from a satellite, the first message including an ID of the satellite and a first random number generated by the satellite for additional authentication between the UE and the satellite; transmitting a second message to the satellite, the second message including an ID of the UE, an authentication value generated by the UE on the basis of the first message, and a second random number generated by the UE for additional authentication between the UE and the satellite; and receiving a third message from the satellite, the third message including an authentication value generated by the satellite on the basis of the second message.

Description

Method and device for improving authentication of satellite communications

The present disclosure relates to a method and device for improving the existing authentication process between a terminal and a network by strengthening authentication of the terminal and the satellite when the satellite communication operates in a store and transmit mode.

5G mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6GHz frequency band such as 3.5 gigahertz (3.5GHz), but also in the ultra-high frequency band called millimeter wave (mmWave) such as 28GHz and 39GHz ('Above 6GHz'). In addition, for 6G mobile communication technology, which is called the system after 5G communication (Beyond 5G), implementation in the terahertz band (for example, the 3 terahertz (3THz) band at 95GHz) is being considered to achieve a transmission speed that is 50 times faster than 5G mobile communication technology and an ultra-low latency time that is reduced to one-tenth.

In the early stages of 5G mobile communication technology, the goal is to support services and satisfy performance requirements for enhanced Mobile Broadband (eMBB), Ultra-Reliable Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). These include beamforming and massive MIMO to mitigate path loss of radio waves in ultra-high frequency bands and increase the transmission distance of radio waves, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of BWP (Bidth Part), new channel coding methods such as LDPC (Low Density Parity Check) codes for large-capacity data transmission and Polar Code for reliable transmission of control information, and L2 pre-processing (L2). Standardization has been made for network slicing, which provides dedicated networks specialized for specific services, and pre-processing.

Currently, discussions are underway to improve and enhance the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, and physical layer standardization is in progress for technologies such as V2X (Vehicle-to-Everything) to help autonomous vehicles make driving decisions and increase user convenience based on their own location and status information transmitted by vehicles, NR-U (New Radio Unlicensed) for the purpose of system operation that complies with various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (UE Power Saving), Non-Terrestrial Network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, and Positioning.

In addition, standardization of wireless interface architecture/protocols is in progress for technologies such as intelligent factories (Industrial Internet of Things, IIoT) to support new services through linkage and convergence with other industries, Integrated Access and Backhaul (IAB) that provides nodes for expanding network service areas by integrating wireless backhaul links and access links, Mobility Enhancement technology including Conditional Handover and Dual Active Protocol Stack (DAPS) handover, and 2-step random access (2-step RACH for NR) that simplifies random access procedures. Standardization is also in progress for system architecture/services such as 5G baseline architecture (e.g., Service-based Architecture, Service-based Interface) for grafting Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) that provides services based on the location of the terminal.

Once these 5G mobile communication systems are commercialized, an explosive increase in connected devices will be connected to the communication network, necessitating enhanced functionality and performance of 5G mobile communication systems and integrated operation of these connected devices. To this end, new research will be conducted on improving 5G performance and reducing complexity, supporting AI services, supporting metaverse services, and drone communications by utilizing eXtended Reality (XR), Artificial Intelligence (AI), and Machine Learning (ML) to efficiently support Augmented Reality (AR), Virtual Reality (VR), and Mixed Reality (MR).

In addition, the development of these 5G mobile communication systems includes new waveforms to ensure coverage in the terahertz band of 6G mobile communication technology, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), Array Antenna, and Large Scale Antenna, metamaterial-based lenses and antennas to improve the coverage of terahertz band signals, high-dimensional spatial multiplexing technology using Orbital Angular Momentum (OAM), Reconfigurable Intelligent Surface (RIS) technology, as well as full duplex technology to improve the frequency efficiency and system network of 6G mobile communication technology, satellite, AI (Artificial Intelligence) from the design stage and AI-based communication technology that realizes system optimization by internalizing end-to-end AI support functions, and ultra-high-performance communication and computing resources to provide services with complexity that exceeds the limits of terminal computing capabilities. It can serve as a basis for the development of next-generation distributed computing technologies that can be realized by utilizing them.

Meanwhile, the need for measures to strengthen authentication between terminals and satellites in satellite communication systems where satellites exist between terminals and networks is emerging.

Based on the discussion described above, the present disclosure seeks to address the following issues:

Authentication in a communications system primarily refers to authentication between a terminal and a network. This also applies to satellite communications systems, where a satellite exists between the terminal and the network.

However, when a satellite communication system operates in store-and-forward mode, if communication between the terminal and the satellite is not secure, authentication between the terminal and the network may not be properly performed. Therefore, additional authentication between the terminal and the satellite may be required when the satellite communication system operates in store-and-forward mode.

The present disclosure provides a description of a method and device for the above additional authentication.

A method of operating a user equipment (UE) in a wireless communication system according to an embodiment of the present disclosure may include receiving a first message from a satellite, the first message including an ID of the satellite and a first random number generated by the satellite for additional authentication of the UE and the satellite; transmitting a second message to the satellite, the second message including an ID of the UE, an authentication value generated by the UE based on the first message, and a second random number generated by the UE for additional authentication of the UE and the satellite; and receiving a third message from the satellite, the third message including an authentication value generated by the satellite based on the second message.

A method for operating a satellite in a wireless communication system according to an embodiment of the present disclosure may include transmitting a first message to a user equipment (UE), the first message including an ID of the satellite and a first random number generated by the satellite for additional authentication of the UE and the satellite; receiving a second message from the UE, the second message including an ID of the UE, an authentication value generated by the UE based on the first message, and a second random number generated by the UE for additional authentication of the UE and the satellite; and transmitting a third message to the UE, the third message including an authentication value generated by the satellite based on the second message.

In a wireless communication system according to an embodiment of the present disclosure, a user equipment (UE) includes a transceiver; and a processor. The processor may control the reception of a first message from a satellite, the first message including an ID of a satellite and a first random number generated by the satellite for additional authentication of the UE and the satellite, the transmission of a second message to the satellite, the second message including an ID of the UE, an authentication value generated by the UE based on the first message, and a second random number generated by the UE for additional authentication of the UE and the satellite, and the reception of a third message from the satellite, the third message including an authentication value generated by the satellite based on the second message.

In a wireless communication system according to an embodiment of the present disclosure, a satellite includes a transceiver; and a processor. The processor may control to transmit a first message including an ID of the satellite and a first random number generated by the satellite for additional authentication of a user equipment (UE) and the satellite to the UE, receive a second message including the ID of the UE, an authentication value generated by the UE based on the first message, and a second random number generated by the UE for additional authentication of the UE and the satellite from the UE, and transmit a third message including an authentication value generated by the satellite based on the second message to the UE.

Various embodiments of the present disclosure can provide a method and apparatus for improving authentication between a terminal and a network by introducing an additional authentication process between the terminal and the satellite when the satellite communication system operates in a store-and-forward mode.

The effects that can be obtained from the present disclosure are not limited to the effects mentioned in the various embodiments, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

FIG. 1 is a conceptual diagram illustrating two different modes of satellite communication to be covered in an embodiment of the present disclosure.

Figure 2 is a conceptual diagram illustrating a key of an encryption system to be handled in an embodiment of the present disclosure.

FIG. 3 is a conceptual diagram illustrating a database for additional authentication to be handled in an embodiment of the present disclosure.

Figure 4 is a conceptual diagram illustrating how the above-described database is used in a specific mode of the above-described satellite communication.

FIG. 5 is a diagram illustrating an authentication process between a terminal and a network of an EPS according to an embodiment of the present disclosure.

FIG. 6 is a diagram illustrating an authentication process between a terminal and a network of an EPS using a satellite communication system according to an embodiment of the present disclosure.

FIG. 7 is a diagram illustrating an authentication process between a 5G terminal and a network according to an embodiment of the present disclosure.

FIG. 8 is a diagram illustrating an authentication process between a terminal and a network of a 5G using a satellite communication system according to an embodiment of the present disclosure.

FIG. 9 is a diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

FIG. 10 is another diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

FIG. 11 is another diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

FIG. 12 is another diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

FIG. 13 is another diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

FIG. 14 is a diagram showing the configuration of a UE according to one embodiment of the present disclosure.

FIG. 15 is a diagram showing the configuration of a network entity according to one embodiment of the present disclosure.

The terms used in this disclosure are used only to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those of ordinary skill in the art described in this disclosure. Terms defined in general dictionaries among the terms used in this disclosure may be interpreted as having the same or similar meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined in this disclosure. In some cases, even if a term is defined in this disclosure, it cannot be interpreted to exclude embodiments of the present disclosure.

The various embodiments of the present disclosure described below illustrate a hardware-based approach as an example. However, since the various embodiments of the present disclosure include techniques utilizing both hardware and software, the various embodiments of the present disclosure do not exclude a software-based approach.

Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings. Furthermore, when describing embodiments of the present disclosure, detailed descriptions of related known functions or configurations will be omitted if they are deemed to unnecessarily obscure the gist of the embodiments. Furthermore, the terms described below are defined in consideration of their functions in the embodiments, and may vary depending on the intent or custom of the user or operator. Therefore, their definitions should be based on the contents throughout this specification.

For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted. Furthermore, the dimensions of each component do not entirely reflect its actual size.

The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described below in detail with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure the completeness of the present disclosure and to fully inform those skilled in the art of the scope of the disclosure, and the present disclosure is defined solely by the scope of the claims.

At this time, it will be understood that each block of the processing flowchart drawings and combinations of the flowchart drawings can be performed by computer program instructions. These computer program instructions can be installed in a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, so that the instructions executed by the processor of the computer or other programmable data processing equipment create a means for performing the functions described in the flowchart block(s). These computer program instructions can also be stored in a computer-available or computer-readable memory that can direct a computer or other programmable data processing equipment to implement the functions in a specific manner, so that the instructions stored in the computer-available or computer-readable memory can also produce a manufactured item that includes an instruction means for performing the functions described in the flowchart block(s). Since the computer program instructions may be installed on a computer or other programmable data processing device, a series of operational steps may be performed on the computer or other programmable data processing device to create a computer-executable process, and the instructions that cause the computer or other programmable data processing device to perform the steps for performing the functions described in the flowchart block(s) may also provide steps for performing the functions described in the flowchart block(s).

Additionally, each block may represent a module, segment, or portion of code that contains one or more executable instructions for performing a specific logical function(s). It should also be noted that in some alternative implementation examples, the functions described in the blocks may occur out of order. For example, two blocks depicted in succession may actually be executed substantially concurrently, or the blocks may sometimes be executed in reverse order, depending on their respective functions.

Here, the term '~ unit' used in various embodiments of the present disclosure means a software or hardware component such as an FPGA or ASIC, and the '~ unit' can perform certain roles. However, the '~ unit' is not limited to software or hardware. The '~ unit' may be configured to be on an addressable storage medium and may be configured to play one or more processors. Accordingly, as an example, the '~ unit' may include components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functions provided within the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. Additionally, components and '~parts' may be implemented to regenerate one or more CPUs within a device or secure multimedia card.

FIG. 1 is a conceptual diagram illustrating two different modes of satellite communication to be covered in an embodiment of the present disclosure.

Specific definitions of the UE, satellite, and ground network (GN) illustrated in Fig. 1 are described in Fig. 5 or Fig. 7.

The communication between the UE and the Satellite illustrated in Fig. 1 may be collectively referred to as a Service link. The communication between the Satellite and the GN illustrated in Fig. 1 may be collectively referred to as a Feeder link.

The two different modes of satellite communication are as follows:

1. Normal mode

When both the Service link and Feeder link are available simultaneously, real-time communication between the UE and GN is possible.

2. Store and Forward mode

When there is a time when the Service link and Feeder link are not available at the same time, real-time communication between the UE and the GN may not be possible. That is, when the Service link is available but the Feeder link is not available, a message sent from the UE to the GN cannot be transmitted to the GN in real time, and the Satellite may store the message and transmit the message to the GN when the Feeder link becomes available. Or, conversely, when the Feeder link is available but the Service link is not available, a message sent from the GN to the UE cannot be transmitted to the UE in real time, and the Satellite may store the message and transmit the message to the UE when the Service link becomes available.

Figure 2 is a conceptual diagram illustrating a key of an encryption system to be handled in an embodiment of the present disclosure.

K _UE may be common confidential information (credential) shared by the terminal and the network. The confidential information may be a symmetric key of a symmetric key cryptosystem. The symmetric key may be the same as the symmetric key (K used in the authentication process of an EPS or 5G system) required for mutual authentication between the network and the terminal of a mobile communication system, or may be a newly defined symmetric key for additional mutual authentication between the satellite and the terminal described in this embodiment.

K _SAT,UE may be a credential derived from K _UE . In particular, K _SAT,UE may be a symmetric key of a symmetric key cryptosystem derived from K _UE .

K _SAT,UE can be derived from K _UE by the terminal and the network. K _SAT,UE can be derived by the network and then transmitted to the satellite.

One or more of the following information may be used to derive K _SAT,UE from K _UE .

- ID.SAT: ID of the satellite that will receive K _SAT,UE from the network. In the present disclosure, the satellite may include a 'base station' and/or 'part and/or all of the core network entity' as components. In the present disclosure, ID.SAT may be one of the following values: 1) ID assigned to the entire satellite, 2) ID of the base station which is one of the components of the satellite, 3) ID of the core network entity among the components of the satellite.

- Nonce: A random number generated by the network to derive K _{SAT, UE} . In this disclosure, the use of the Nonce value may be optional. That is, although the embodiments in this disclosure are written only for cases where the Nonce value is used, when the Nonce value is not used, all operations related to the Nonce may be omitted in embodiments to be disclosed later.

FIG. 3 is a conceptual diagram illustrating a database for additional authentication to be handled in an embodiment of the present disclosure.

The above database may be a database used for additional mutual authentication between the terminal and satellite described in the present disclosure. The above database may be a database generated by the network for additional mutual authentication between the terminal and satellite. The above database may be a database generated by the network and transmitted to the satellite for additional mutual authentication between the terminal and satellite.

The above database can be created in the following manner.

- The network prepares the following values for each terminal:

■ ID.UE: Terminal ID. In the present disclosure, ID.UE may be the same as an ID previously used by the network of a mobile communication system to identify a terminal (such as IMSI used in EPS or SUPI used in a 5G system), or may be a newly defined ID for additional mutual authentication between the satellite and the terminal described in this embodiment.

■ Nonce: A random number generated by the network to derive the following K _SAT,UE

■ K _SAT,UE : Credential to be used for additional mutual authentication between the 'terminal' and the 'satellite to receive the database'. The derivation of K _SAT,UE can follow the process of Fig. 2. If the process of Fig. 2 is followed, the 'ID of the satellite to receive the database' and the 'Nonce' value can be used to derivate K _SAT,UE .

- The network collects the prepared values for multiple terminals and creates a table as shown in Figure 3. At this time, the Nonce values may be different for each UE or may be common values.

In the present disclosure, the database may be referred to as PAM (Partial Authentication Management).

Figure 4 is a conceptual diagram illustrating how the above-described database is used in a specific mode of the above-described satellite communication.

This conceptual diagram presents a schematic process for enabling additional mutual authentication between a terminal and a satellite using the database created in Figure 3.

In STEP 1, one or more of the following steps may be performed:

- The network can generate PAM. The definition and generation process of PAM are described in Figure 3.

In STEP 2, one or more of the following steps may be performed:

- The network can transmit the PAM generated above via satellite.

In STEP 3, one or more of the following steps may be performed:

- The satellite and terminal can use PAM for additional mutual authentication. For a detailed description of the additional mutual authentication, refer to the embodiments described later.

FIG. 5 is a diagram illustrating an authentication process between a terminal and a network of an EPS according to an embodiment of the present disclosure.

The UE illustrated in FIG. 5 is an abbreviation for user equipment, and is also collectively called a terminal, and may include a mobile station (MS), a cellular phone, a smartphone, a computer, an IoT device, or a multimedia system capable of performing a communication function.

The eNB illustrated in FIG. 5 is an entity that performs resource allocation of the UE, and may be at least one of an eNode B, a Node B, a BS (base station), a RAN (radio access network), an AN (access network), a RAN node, a NR NB, a gNB, a radio access unit, a base station controller, or a node on a network.

The MME illustrated in FIG. 5 may be an entity that provides mobility management functions and session management functions of the UE.

The HSS illustrated in Fig. 5 may be an entity that provides data management functions such as subscriber data and policy control data.

The authentication process between the terminal and the network of the EPS system can be as follows.

At step 501, one or more of the following processes may be performed:

- The UE can request network access to the MME. An ID identifying the UE may be transmitted during the above process.

At step 502, one or more of the following processes may be performed:

- The MME may request information to authenticate the UE with the HSS. An ID identifying the UE may be transmitted during the process.

At step 503, one or more of the following processes may be performed:

- After verifying the terminal's ID, the HSS can generate information necessary for authenticating the terminal. This information may be referred to as an authentication vector (AV).

At step 504, one or more of the following steps may be performed:

- The HSS may transmit an authentication vector to the MME. The authentication vector may include one or more of the following information:

■ AUTH: The above information is information that can verify the validity of the network, and the UE can verify the above information to authenticate the network.

■ XRES: The above information is information that can verify the validity of the terminal, and the network can use the above information to authenticate the terminal.

At step 505, one or more of the following processes may be performed:

- MME can send AUTH to UE.

At step 506, one or more of the following processes may be performed:

- The terminal can verify AUTH. The terminal can authenticate the network by verifying AUTH.

At step 507, one or more of the following processes may be performed:

- The terminal can generate RES. The above information may be used by the network in the process of verifying the validity of the terminal.

- The terminal can transmit the RES generated by the MME.

At step 508, one or more of the following processes may be performed:

- The MME can verify the RES. The above verification process may be a process of checking whether the 'XRES value received in step 4' and the 'RES value received in step 7' match. If the two values match as a result of the above verification, the network can authenticate the terminal.

At step 509, one or more of the following processes may be performed:

- If mutual authentication between the terminal and the network is successful, the terminal and the network can generate a security key for future secure communication.

FIG. 6 is a diagram illustrating an authentication process between a terminal and a network of an EPS using a satellite communication system according to an embodiment of the present disclosure.

The UE illustrated in FIG. 6 may be the UE illustrated in FIG. 5. The Satellite illustrated in FIG. 6 may include the eNB disclosed in FIG. 5. The Satellite illustrated in FIG. 6 may include part and/or all of the MME disclosed in FIG. 5. The GN illustrated in FIG. 6 may include part and/or all of the MME disclosed in FIG. 5. The GN illustrated in FIG. 6 may include the HSS disclosed in FIG. 5.

The authentication process disclosed in Fig. 6 is a process modified from the authentication process disclosed in Fig. 5 to suit satellite communication in the storage and transmission mode. The process may be as follows.

STEP 1. (Service Link is available / Feeder Link is unavailable)

STEP 1, commonly referred to as the Attach Request Procedure, essentially corresponds to Step 501 of FIG. 5. However, in satellite communications in store-and-forward mode, the terminal and satellite may require additional authentication. In this case, Step 501 of FIG. 5 may not be sufficient and additional steps may be required. A detailed description of the additional steps will be provided in FIGS. 9 through 13.

STEP 2. (Service Link is unavailable / Feeder Link is available)

At step 601, one or more of the following processes may be performed:

- A process corresponding to step 502 of FIG. 5 can be performed.

At step 602, one or more of the following processes may be performed:

- A process corresponding to steps 503 to 504 of FIG. 5 can be performed.

STEP 3. (Service Link is available / Feeder Link is unavailable)

At step 603, one or more of the following processes may be performed:

- The UE can make an Attach Request to the Satellite again.

After step 3, processes corresponding to steps 505 to 509 of FIG. 5 may be performed.

FIG. 7 is a diagram illustrating an authentication process between a 5G terminal and a network according to an embodiment of the present disclosure.

The UE illustrated in FIG. 7 is an abbreviation for user equipment, and is also collectively called a terminal, and may include a mobile station (MS), a cellular phone, a smartphone, a computer, an IoT device, or a multimedia system capable of performing a communication function.

SEAF, shown in Figure 7, is an abbreviation for Security Anchor Function and can act as a middleman in the authentication process.

AUSF, shown in Fig. 7, is an abbreviation for Authentication Server Function and may be a network function responsible for authentication with a terminal.

UDM, shown in Figure 7, is an abbreviation for Unified Data Management and may be an entity that provides data management functions such as subscriber data and policy control data.

The authentication process disclosed in Fig. 7 may be as follows.

At step 701, one or more of the following processes may be performed:

- UE can request access to SEAF.

At step 702, one or more of the following processes may be performed:

- SEAF may request AUSF to initiate certification. AUSF may request data for certification from UDM.

At step 703, one or more of the following processes may be performed:

- UDM can generate data AV (Authentication Vector) for authentication. The AV can include AUTH and XRES. The AUTH can be information used when the terminal authenticates the network. The XRES can be information used when the network authenticates the terminal.

At step 704, one or more of the following processes may be performed:

- UDM can transmit AUTH and XRES to AUSF.

At step 705, one or more of the following processes may be performed:

- AUSF can generate HXRES from the received XRES.

At step 706, one or more of the following processes may be performed:

- AUSF can transmit AUTH and HXRES to SEAF.

At step 707, one or more of the following processes may be performed:

- SEAF can send AUTH to UE.

At step 708, one or more of the following processes may be performed:

- UE can authenticate the network using AIUTH.

- UE can generate RES.

At step 709, one or more of the following processes may be performed:

- UE can transmit RES to SEAF.

At step 710, one or more of the following processes may be performed:

- SEAF can authenticate a terminal by verifying the RES. However, this authentication may not complete terminal authentication on the network.

At step 711, one or more of the following processes may be performed:

- SEAF can send RES to AUSF. The above process can be performed if authentication in step 710 is successful.

At step 712, one or more of the following processes may be performed:

- AUSF can authenticate RES. This process can terminate UE authentication in the network.

At step 713, one or more of the following processes may be performed:

- AUSF can notify SEAF that terminal authentication on the network has been successful.

At step 714, one or more of the following processes may be performed:

- UE and SEAF can perform the remaining procedures for secure NAS communication.

FIG. 8 is a diagram illustrating an authentication process between a terminal and a network of a 5G using a satellite communication system according to an embodiment of the present disclosure.

The UE illustrated in FIG. 8 may be the UE illustrated in FIG. 7. The Satellite illustrated in FIG. 8 may include a portion and/or all of the SEAF disclosed in FIG. 7. The Satellite illustrated in FIG. 8 may include a portion and/or all of the ASUF disclosed in FIG. 7. The GN illustrated in FIG. 8 may include a portion and/or all of the SEAF disclosed in FIG. 7. The GN illustrated in FIG. 8 may include a portion and/or all of the AUSF disclosed in FIG. 7. The GN illustrated in FIG. 8 may include the UDM disclosed in FIG. 7.

The authentication process disclosed in Fig. 8 is a modification of the authentication process disclosed in Fig. 7, adapted to satellite communication in the storage and transmission mode. The modified process may be as follows.

STEP 1. (Service Link is available / Feeder Link is unavailable)

STEP 1, commonly referred to as the Attach Request Procedure, essentially corresponds to Step 701 of FIG. 7. However, in satellite communications in store-and-forward mode, the terminal and satellite may require additional authentication. In this case, Step 701 of FIG. 7 may not be sufficient and additional steps may be required. A detailed description of the additional steps will be provided in FIGS. 9 through 13.

STEP 2. (Service Link is unavailable / Feeder Link is available)

At step 801, one or more of the following processes may be performed:

- A process corresponding to step 702 of Fig. 7 can be performed.

At step 802, one or more of the following processes may be performed:

- A process corresponding to steps 703 to 706 of FIG. 7 can be performed.

STEP 3.

At step 803, one or more of the following processes may be performed:

- The UE can make an Attach Request to the Satellite again.

After step 803, processes corresponding to steps 707 to 714 of FIG. 7 may be performed. When performing processes corresponding to steps 707 to 714 of FIG. 7, communication between the UE and SEAF may be performed in a situation where 'Service Link is available / Feeder Link is unavailable', and communication between the SEAF and AUSF may be performed in a situation where 'Service Link is unavailable / Feeder Link is available'.

FIG. 9 is a diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

That is, the disclosure of FIG. 9 may be a process corresponding to the Attach Request Procedure of FIG. 6 or FIG. 8. At this time, the definitions of the UE and Satellite may follow the definitions disclosed in FIG. 6 and FIG. 8.

The additional authentication process of Fig. 9 may be as follows.

At step 901, one or more of the following processes may be performed:

- Satellite may transmit one or more of the following information to UE:

■ ID.SAT: Satellite ID. The above ID may be the Satellite ID used to derive the PAM information held by the Satellite. For a description of PAM, refer to Fig. 3.

■ Nonce: The Nonce value included in the PAM held by the Satellite. In this case, the Nonce value included in the PAM may not differ by UE and may be the same value for all UEs.

■ RN.SAT: A random number generated by the Satellite for additional authentication of the terminal and satellite. In this case, the random value may not differ by UE and may be the same for all UEs.

At step 902, one or more of the following processes may be performed:

- The UE may perform one or more of the following processes:

■ The UE can create K _SAT,UE using the K _UE it owns and the information (ID.SAT and/or Nonce) received in step 1.

■ The UE can generate an authentication value SIG.UE for RN.SAT (and/or ID.UE and/or RN.UE) using the above-mentioned generated K _SAT,UE . In the above process, K _SAT,UE may be used as a credential for generating the authentication value, or another value derived from K _SAT,UE may be used. In the above process, RN.SAT, which is the source of the authentication value generation, may be encrypted using the above-mentioned credential or may be integrity protected in the form of a message authenticity code.

- The UE may transmit one or more of the following information to the Satellite:

■ ID.UE: UE ID. The above information is included in the PAM held by the Satellite, and may be an identifier that allows the Satellite to identify the UE.

■ SIG.UE: Authentication value generated above

■ RN.UE: A random number generated by the UE for additional authentication of the terminal and satellite.

In step 3, one or more of the following processes may be performed:

- Satellite can perform one or more of the following processes:

■ Satellite can obtain K _SAT,UE of the UE that transmitted the ID by searching PAM using the received ID.UE.

■ The satellite can verify the validity of the SIG.UE transmitted by the UE using the K _SAT,UE acquired above. Through the above process, the satellite can authenticate the terminal.

■ Satellite can generate an authentication value SIG.SAT for RN.UE using the K _SAT,UE acquired above. In the above process, K _SAT,UE may be used as the credential for generating the authentication value, or another value derived from K _SAT,UE may be used. In the above process, RN.UE, which is the target of authentication value generation, may be encrypted using the above-mentioned credential or may be integrity protected in the form of a message authenticity code.

- The Satellite may transmit one or more of the following information to the UE. In addition to the information described below, the Satellite may also transmit additional information necessary for the UE to access the network. The information transmitted by the Satellite to the UE may be securely protected. (For example, to prevent a third party from verifying or falsifying the information transmitted by the Satellite to the UE.) The credential used for protection may be K _SAT,UE or another value derived from K _SAT,UE . The protection may be achieved by encryption using the credential, or an integrity protection technique (such as a Message Authentication Code, for example) may be used.

■ SIG.SAT: Authentication value generated above

- The UE may perform one or more of the following processes:

■ If the received message is protected, the UE can perform the following steps: If the received message is encrypted, it can decrypt it and verify the contents. If the received message is integrity protected, it can verify the integrity of the received message.

■ The UE can authenticate the satellite by verifying the validity of the received SIG.SAT.

According to one embodiment, at least one operation illustrated in FIG. 9 can be used in STEP 1 of FIG. 6 or STEP 1 of FIG. 8. According to one embodiment, at least one operation illustrated in FIG. 9 can also be applied to STEP 3 of FIG. 6 or STEP 3 of FIG. 8. When applied, some of the operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' already described may be changed as follows. (Operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' that are not described below are identical to the operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' already described.)

[When the embodiment of Fig. 9 is applied to STEP 3 of Fig. 6]

As described above, STEP 3 of FIG. 6 can be composed of the sequential progression of ‘Step 603 of FIG. 6’ and ‘Steps 505 to 509 of FIG. 5’.

According to one embodiment, the embodiment of FIG. 9 can be applied to STEP3 of FIG. 6 in the manner described below.

In one embodiment, step 901 of FIG. 9 may be performed before step 3 of FIG. 6 is executed.

In one embodiment, steps 603 of FIG. 6 and 902 of FIG. 9 may be combined as follows: The UE may transmit the message described in step 603 of FIG. 6 to the satellite. The UE may further transmit the message described in step 902 of FIG. 9 to the satellite. In this case, the message described in step 603 of FIG. 6 may further be included in the source for generating the SIG.UE described in step 902 of FIG. 9.

In one embodiment, the operations following step 603 of FIG. 6, step 505 of FIG. 5 and step 903 of FIG. 9 may be combined as follows: The satellite may transmit the message described in step 505 of FIG. 5 to the UE. The satellite may further transmit the message described in step 903 of FIG. 9 to the UE. At this time, the message described in step 505 of FIG. 5 may further be included in the source for generating SIG.SAT described in step 903 of FIG. 9.

[When the embodiment of Fig. 9 is applied to STEP 3 of Fig. 8]

As described above, STEP 3 of FIG. 8 can be composed of the sequential progression of ‘Step 803 of FIG. 8’ and ‘Steps 707 to 714 of FIG. 7’.

According to one embodiment, the disclosure of FIG. 9 can be applied to STEP3 of FIG. 8 in a manner described below.

In one embodiment, step 901 of FIG. 9 may be performed before step 803 of FIG. 8 is performed.

In one embodiment, steps 803 of FIG. 8 and 902 of FIG. 9 may be combined as follows: The UE may transmit the message described in step 803 of FIG. 8 to the satellite. The UE may further transmit the message described in step 902 of FIG. 9 to the satellite. In this case, the message described in step 803 of FIG. 8 may further be included in the source for generating the SIG.UE described in step 902 of FIG. 9.

In one embodiment, the operations following step 803 of FIG. 8, step 707 of FIG. 7 and step 903 of FIG. 9 may be combined as follows: The satellite may transmit the message described in step 707 of FIG. 7 to the UE. The satellite may further transmit the message described in step 903 of FIG. 9 to the UE. At this time, the message described in step 707 of FIG. 7 may further be included in the source for generating SIG.SAT described in step 903 of FIG. 9.

FIG. 10 is another diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

That is, the disclosure of FIG. 10 may be a process corresponding to the Attach Request Procedure of FIG. 6 or FIG. 8. At this time, the definitions of the UE and Satellite may follow the definitions disclosed in FIG. 6 and FIG. 8.

The additional authentication process of Fig. 10 may be as follows.

At step 1001, one or more of the following processes may be performed:

- Satellite may transmit one or more of the following information to UE:

■ ID.SAT: Satellite ID. The above ID may be the Satellite ID used to derive the PAM information held by the Satellite. For a description of PAM, refer to Fig. 3.

■ Nonce: The Nonce value included in the PAM held by the Satellite. In this case, the Nonce value included in the PAM may not differ by UE and may be the same value for all UEs.

At step 1002, one or more of the following processes may be performed:

- The UE may perform one or more of the following processes:

■ The UE can create K _SAT,UE using the K _UE it owns and the information (ID.SAT and/or Nonce) received in step 1.

■ The UE can generate a value SIG.UE that can verify itself using the K _SAT,UE generated above.

In the above process, K _SAT,UE may be used as a credential for generating an authentication value, or another value derived from K _SAT,UE may be used.

In the above process, an arbitrary value (and/or ID.UE) that ensures the refreshability of the current session (and can prevent replay attacks) can be used as the source of authentication value generation. One example of a value that ensures refreshability is the current time. If current time information is used, various verification mechanisms utilizing it can be utilized. For example, a verifier can verify whether the received time information is acceptable within a certain error range. If the received time information falls within the acceptable error range, the verifier can determine that the information is valid.

In the above process, the source of authentication value generation can be encrypted using the above-mentioned credential or integrity protected in the form of a message authenticity code.

- The UE may transmit one or more of the following information to the Satellite:

■ IE.UE: UE ID. The above information is included in the PAM held by the Satellite, and may be an identifier that allows the Satellite to identify the UE.

■ SIG.UE: Authentication value generated above

In step 3, one or more of the following processes may be performed:

- Satellite can perform one or more of the following processes:

■ Satellite can obtain K _SAT,UE of the UE that transmitted the ID by searching PAM using the received ID.UE.

■ The satellite can verify the validity of the SIG.UE transmitted by the UE using the K _SAT,UE acquired above. Through the above process, the satellite can authenticate the terminal.

■ Satellite can generate a value SIG.SAT that can verify itself using the K _SAT,UE obtained above.

In the above process, K _SAT,UE may be used as a credential for generating an authentication value, or another value derived from K _SAT,UE may be used.

In the above process, any arbitrary value that guarantees the refreshability of the current session (and can prevent replay attacks) can be used as the source of authentication value generation. As an example of a value that guarantees refreshability, the source of authentication value generation in the above process may be the current time information. If current time information is used, various verification mechanisms utilizing it can be utilized. For example, the verifier can verify whether the received time information is acceptable within a certain error range. If the received time information falls within the acceptable error range, the content of the information can be deemed valid.

In the above process, the source of authentication value generation can be encrypted using the above-mentioned credential or integrity protected in the form of a message authenticity code.

- Satellite may transmit one or more of the following information to UE:

■ SIG.SAT: Authentication value generated above

- The UE may perform one or more of the following processes:

■ The UE can authenticate the satellite by verifying the validity of the received SIG.SAT.

According to one embodiment, at least one operation illustrated in FIG. 10 can be used in STEP 1 of FIG. 6 or STEP 1 of FIG. 8. According to one embodiment, at least one operation illustrated in FIG. 10 can also be applied to STEP 3 of FIG. 6 or STEP 3 of FIG. 8. According to one embodiment, when at least one operation illustrated in FIG. 10 is applied, some of the operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' already described may be changed as follows. (Operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' that are not described below are identical to operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' that have already been described.)

[When the embodiment of Fig. 10 is applied to STEP 3 of Fig. 6]

As described above, STEP 3 of FIG. 6 can be composed of the sequential progression of ‘Step 603 of FIG. 6’ and ‘Steps 505 to 509 of FIG. 5’.

According to one embodiment, the embodiment of FIG. 10 can be applied to STEP3 of FIG. 6 in a manner described below.

In one embodiment, step 1001 of FIG. 10 may be performed before step 603 of FIG. 6 is performed.

In one embodiment, steps 603 of FIG. 6 and 1002 of FIG. 10 may be combined as follows: The UE may transmit the message described in step 603 of FIG. 6 to the satellite. The UE may further transmit the message described in step 1002 of FIG. 10 to the satellite. In this case, the message described in step 603 of FIG. 6 may further be included in the source for generating the SIG.UE described in step 1002 of FIG. 10.

In one embodiment, the operations following step 603 of FIG. 6, step 505 of FIG. 5 and step 1003 of FIG. 10 may be combined as follows: The satellite may transmit the message described in step 505 of FIG. 5 to the UE. The satellite may further transmit the message described in step 1003 of FIG. 10 to the UE. At this time, the message described in step 505 of FIG. 5 may further be included in the source for generating SIG.SAT described in step 1003 of FIG. 10.

[When the embodiment of Fig. 10 is applied to STEP 3 of Fig. 8]

As described above, STEP 3 of FIG. 8 can be composed of the sequential progression of ‘Step 803 of FIG. 8’ and ‘Steps 707 to 714 of FIG. 7’.

According to one embodiment, the embodiment of FIG. 10 can be applied to STEP3 of FIG. 8 in a manner described below.

In one embodiment, step 1001 of FIG. 10 may be performed before step 803 of FIG. 8 is performed.

In one embodiment, steps 803 of FIG. 8 and 1002 of FIG. 10 may be combined as follows: The UE may transmit the message described in step 803 of FIG. 8 to the satellite. The UE may further transmit the message described in step 1002 of FIG. 10 to the satellite. In this case, the message described in step 803 of FIG. 8 may further be included in the source for generating the SIG.UE described in step 1002 of FIG. 10.

In one embodiment, the operations following step 803 of FIG. 8, step 707 of FIG. 7 and step 1003 of FIG. 10 may be combined as follows: The satellite may transmit the message described in step 707 of FIG. 7 to the UE. The satellite may further transmit the message described in step 1003 of FIG. 10 to the UE. At this time, the message described in step 707 of FIG. 7 may further be included in the source for generating SIG.SAT described in step 1003 of FIG. 10.

FIG. 11 is another diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

That is, the disclosure of FIG. 11 may be a process corresponding to the Attach Request Procedure of FIG. 6 or FIG. 8. At this time, the definitions of the UE and Satellite may follow the definitions disclosed in FIG. 6 and FIG. 8.

The additional authentication process of Fig. 11 may be as follows.

At step 1101, one or more of the following processes may be performed:

- Satellite may transmit one or more of the following information to UE:

■ ID.SAT: Satellite ID. The above ID may be the Satellite ID used to derive the PAM information held by the Satellite. For a description of PAM, refer to Fig. 3.

■ Nonce: The Nonce value included in the PAM held by the Satellite. In this case, the Nonce value included in the PAM may not differ by UE and may be the same value for all UEs.

At step 1102, one or more of the following processes may be performed:

- The UE may transmit one or more of the following information to the Satellite:

■ IE.UE: UE ID. The above information is included in the PAM held by the Satellite, and may be an identifier that allows the Satellite to identify the UE.

■ RN.UE: A random number generated by the UE for additional authentication of the terminal and satellite.

At step 1103, one or more of the following processes may be performed:

- Satellite can perform one or more of the following processes:

■ Satellite can obtain K _SAT,UE of the UE that transmitted the ID by searching PAM using the received ID.UE.

■ Satellite can generate authentication value SIG.SAT for RN.UE (and/or RN.SAT) using K _SAT,UE acquired above. In the above process, K _SAT,UE may be used as the credential for generating authentication value, or another value derived from K _SAT,UE may be used. In the above process, RN.UE, which is the target of authentication value generation, may be encrypted using the above-mentioned credential or may be integrity protected in the form of a message authenticity code.

- Satellite may transmit one or more of the following information to UE:

■ SIG.SAT: Authentication value generated above

■ RN.SAT: A random number generated by the Satellite for additional authentication between the terminal and the satellite. In this case, the random value may be different for each UE or may be the same for all UEs.

At step 1104, one or more of the following processes may be performed:

- The UE may perform one or more of the following processes:

■ The UE can authenticate the satellite by verifying the validity of the received SIG.SAT.

■ The UE can create K _SAT,UE using the K _UE it owns and the information (ID.SAT and/or Nonce) received in step 1.

■ The UE can generate an authentication value SIG.UE for RN.SAT using the above-mentioned K _SAT,UE . In the above process, K _SAT,UE may be used as the credential for generating the authentication value, or another value derived from K _SAT,UE may be used. In the above process, RN.SAT, which is the source of the authentication value generation, may be encrypted using the above-mentioned credential or may be integrity protected in the form of a message authenticity code.

- The UE may transmit one or more of the following information to the Satellite:

■ SIG.UE: Authentication value generated above

- Satellite can perform one or more of the following processes:

■ The satellite can verify the validity of the SIG.UE transmitted by the UE using the K _SAT,UE acquired above. Through the above process, the satellite can authenticate the terminal.

According to one embodiment, at least one operation illustrated in FIG. 11 can be used in STEP 1 of FIG. 6 or STEP 1 of FIG. 8. According to one embodiment, at least one operation illustrated in FIG. 11 can also be applied to STEP 3 of FIG. 6 or STEP 3 of FIG. 8. According to one embodiment, when at least one operation illustrated in FIG. 11 is applied, some of the operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' already described may be changed as follows. (Operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' that are not described below are identical to operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' that have already been described.)

[When the embodiment of Fig. 11 is applied to STEP 3 of Fig. 6]

According to one embodiment, STEP 3 of FIG. 6 may be composed of the sequential progression of 'Step 603 of FIG. 6' and 'Steps 505 to 509 of FIG. 5'.

According to one embodiment, the embodiment of FIG. 11 can be applied to STEP3 of FIG. 6 in a manner described below.

In one embodiment, step 1101 of FIG. 11 may be performed before step 603 of FIG. 6 is performed.

In one embodiment, steps 603 of FIG. 6 and 1102 of FIG. 11 may be combined as follows: The UE may transmit the message described in step 603 of FIG. 6 to the satellite. The UE may further transmit the message described in step 1102 of FIG. 11 to the satellite.

In one embodiment, the operations following step 603 of FIG. 6, step 505 of FIG. 5 and step 1103 of FIG. 11, may be combined as follows: The satellite may transmit the message described in step 505 of FIG. 5 to the UE. The satellite may further transmit the message described in step 1103 of FIG. 11 to the UE. At this time, the message described in step 505 of FIG. 5 may further be included in the source for generating SIG.SAT described in step 1103 of FIG. 11.

In one embodiment, the operations following step 603 of FIG. 6, step 507 of FIG. 5 and step 504 of FIG. 11 may be combined as follows: The UE may transmit the message described in step 507 of FIG. 5 to the satellite. The UE may further transmit the message described in step 1104 of FIG. 11 to the satellite. At this time, the message described in step 507 of FIG. 5 may further be included in the source for generating SIG.UE described in step 1104 of FIG. 11.

[When the embodiment of Fig. 11 is applied to STEP 3 of Fig. 8]

According to one embodiment, STEP 3 of FIG. 8 may be composed of the sequential progression of 'Step 803 of FIG. 8' and 'Steps 707 to 714 of FIG. 7'.

According to one embodiment, the embodiment of FIG. 11 can be applied to STEP3 of FIG. 8 in a manner described below.

In one embodiment, step 1101 of FIG. 11 may be performed before step 803 of FIG. 8 is performed.

In one embodiment, steps 803 of FIG. 8 and 1102 of FIG. 11 may be combined as follows: The UE may transmit the message described in step 803 of FIG. 8 to the satellite. The UE may further transmit the message described in step 1102 of FIG. 11 to the satellite.

In one embodiment, the operations following step 803 of FIG. 8, step 707 of FIG. 7 and step 1103 of FIG. 11 may be combined as follows: The satellite may transmit the message described in step 707 of FIG. 7 to the UE. The satellite may further transmit the message described in step 1103 of FIG. 11 to the UE. At this time, the message described in step 707 of FIG. 7 may further be included in the source for generating SIG.SAT described in step 1103 of FIG. 11.

In one embodiment, the operations following step 803 of FIG. 8, step 709 of FIG. 7 and step 1104 of FIG. 11 may be combined as follows: The UE may transmit the message described in step 709 of FIG. 7 to the satellite. The UE may further transmit the message described in step 1104 of FIG. 11 to the satellite. At this time, the message described in step 709 of FIG. 7 may further be included in the source for generating SIG.UE described in step 1104 of FIG. 11.

FIG. 12 is another diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

That is, the disclosure of FIG. 12 may be a process corresponding to the Attach Request Procedure of FIG. 6 or FIG. 8. At this time, the definitions of the UE and Satellite may follow the definitions disclosed in FIG. 6 and FIG. 8.

The additional authentication process of Fig. 12 may be as follows.

At step 1201, one or more of the following processes may be performed:

- Satellite may transmit one or more of the following information to UE:

■ ID.SAT: Satellite ID. The above ID may be the Satellite ID used to derive the PAM information held by the Satellite. For a description of PAM, refer to Fig. 3.

At step 1202, one or more of the following processes may be performed:

- The UE may transmit one or more of the following information to the Satellite:

■ IE.UE: UE ID. The above information is included in the PAM held by the Satellite, and may be an identifier that allows the Satellite to identify the UE.

■ RN.UE: A random number generated by the UE for additional authentication of the terminal and satellite.

At step 1203, one or more of the following processes may be performed:

- Satellite can perform one or more of the following processes:

■ Satellite can obtain K _SAT,UE of the UE that transmitted the ID by searching PAM using the received ID.UE.

■ Satellite can generate an authentication value SIG.SAT for RN.UE (and/or Nonce and/or RN.SAT) using the above-obtained K _SAT,UE . In the above process, K _SAT,UE may be used as the credential for generating the authentication value, or another value derived from K _SAT,UE may be used. In the above process, RN.UE, which is the target of authentication value generation, may be encrypted using the above-mentioned credential or may be integrity protected in the form of a message authenticity code.

- Satellite may transmit one or more of the following information to UE:

■ SIG.SAT: Authentication value generated above

■ Nonce: Nonce value included in the PAM held by the Satellite. In this case, the Nonce value included in the PAM may be different for each UE, or may be the same value for all UEs.

■ RN.SAT: A random number generated by the Satellite for additional authentication between the terminal and the satellite. In this case, the random value may be different for each UE or may be the same for all UEs.

At step 1204, one or more of the following processes may be performed:

- The UE may perform one or more of the following processes:

■ The UE can authenticate the satellite by verifying the validity of the received SIG.SAT.

■ The UE can create K _SAT,UE using the K _UE it owns and the information (ID.SAT and/or Nonce) received in step 1.

■ The UE can generate an authentication value SIG.UE for RN.SAT using the above-mentioned K _SAT,UE . In the above process, K _SAT,UE may be used as the credential for generating the authentication value, or another value derived from K _SAT,UE may be used. In the above process, RN.SAT, which is the source of the authentication value generation, may be encrypted using the above-mentioned credential or may be integrity protected in the form of a message authenticity code.

- The UE may transmit one or more of the following information to the Satellite:

■ SIG.UE: Authentication value generated above

■ Satellite can perform one or more of the following processes:

■ The satellite can verify the validity of the SIG.UE transmitted by the UE using the K _SAT,UE acquired above. Through the above process, the satellite can authenticate the terminal.

According to one embodiment, at least one operation illustrated in FIG. 12 can be used in STEP 1 of FIG. 6 or STEP 1 of FIG. 8. According to one embodiment, at least one operation illustrated in FIG. 12 can also be applied to STEP 3 of FIG. 6 or STEP 3 of FIG. 8. According to one embodiment, when at least one operation illustrated in FIG. 12 is applied, some of the operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' already described may be changed as follows. (Operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' that are not described below are identical to operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' that have already been described.)

[When the embodiment of Fig. 12 is applied to STEP 3 of Fig. 6]

As described above, STEP 3 of FIG. 6 can be composed of the sequential progression of ‘Step 603 of FIG. 6’ and ‘Steps 505 to 509 of FIG. 5’.

According to one embodiment, the embodiment of FIG. 12 can be applied to STEP3 of FIG. 6 in a manner described below.

In one embodiment, step 1201 of FIG. 12 may be performed before step 603 of FIG. 6 is performed.

In one embodiment, steps 603 of FIG. 6 and 1202 of FIG. 12 may be combined as follows: The UE may transmit the message described in step 603 of FIG. 6 to the satellite. The UE may further transmit the message described in step 1202 of FIG. 12 to the satellite.

In one embodiment, the operations following step 603 of FIG. 6, step 505 of FIG. 5 and step 1203 of FIG. 12, may be combined as follows: The satellite may transmit the message described in step 505 of FIG. 5 to the UE. The satellite may further transmit the message described in step 1203 of FIG. 12 to the UE. At this time, the message described in step 505 of FIG. 5 may further be included in the source for generating SIG.SAT described in step 1203 of FIG. 12.

In one embodiment, the operations following step 603 of FIG. 6, step 507 of FIG. 5 and step 1204 of FIG. 12, may be combined as follows: The UE may transmit the message described in step 507 of FIG. 5 to the satellite. The UE may further transmit the message described in step 1204 of FIG. 12 to the satellite. At this time, the message described in step 507 of FIG. 5 may further be included in the source for generating SIG.UE described in step 1204 of FIG. 12.

[When the embodiment of Fig. 12 is applied to STEP 3 of Fig. 8]

As described above, STEP 3 of FIG. 8 can be composed of the sequential progression of ‘Step 803 of FIG. 8’ and ‘Steps 707 to 714 of FIG. 7’.

According to one embodiment, the embodiment of FIG. 12 can be applied to STEP3 of FIG. 8 in a manner described below.

In one embodiment, step 1201 of FIG. 12 may be performed before step 803 of FIG. 8 is performed.

In one embodiment, steps 803 of FIG. 8 and 1202 of FIG. 12 may be combined as follows: The UE may transmit the message described in step 803 of FIG. 8 to the satellite. The UE may further transmit the message described in step 1202 of FIG. 12 to the satellite.

In one embodiment, the operations following step 1203 of FIG. 8, step 707 of FIG. 7 and step 1203 of FIG. 12 may be combined as follows: The satellite may transmit the message described in step 707 of FIG. 7 to the UE. The satellite may further transmit the message described in step 1203 of FIG. 12 to the UE. At this time, the message described in step 707 of FIG. 7 may further be included in the source for generating SIG.SAT described in step 1203 of FIG. 12.

In one embodiment, the operations following step 803 of FIG. 8, step 709 of FIG. 7 and step 1204 of FIG. 12 may be combined as follows: The UE may transmit the message described in step 709 of FIG. 7 to the satellite. The UE may further transmit the message described in step 1204 of FIG. 12 to the satellite. At this time, the message described in step 1209 of FIG. 7 may further be included in the source for generating SIG.UE described in step 1204 of FIG. 12.

FIG. 13 is another diagram illustrating an additional authentication process performed between a terminal and a satellite to enhance security during the terminal and network authentication process of a satellite communication system according to an embodiment of the present disclosure.

That is, the disclosure of FIG. 13 may be a process corresponding to the Attach Request Procedure of FIG. 6 or FIG. 8. At this time, the definitions of the UE and Satellite may follow the definitions disclosed in FIG. 6 and FIG. 8.

The additional authentication process of Fig. 13 may be as follows.

At step 1301, one or more of the following processes may be performed:

- Satellite may transmit one or more of the following information to UE:

■ ID.SAT: Satellite ID. The above ID may be the Satellite ID used to derive the PAM information held by the Satellite. For a description of PAM, refer to Fig. 3.

At step 1302, one or more of the following processes may be performed:

- The UE may transmit one or more of the following information to the Satellite:

■ IE.UE: UE ID. The above information is included in the PAM held by the Satellite, and may be an identifier that allows the Satellite to identify the UE.

At step 1303, one or more of the following processes may be performed:

- Satellite can perform one or more of the following processes:

■ Satellite can obtain K _SAT,UE of the UE that transmitted the ID by searching PAM using the received ID.UE.

■ Satellite can generate a value SIG.SAT that can verify itself using the K _SAT,UE obtained above.

In the above process, K _SAT,UE may be used as a credential for generating an authentication value, or another value derived from K _SAT,UE may be used.

In the above process, an arbitrary value (and/or nonce) that guarantees the refreshability of the current session (and can prevent replay attacks) can be used as the source of authentication value generation. As an example of a value that guarantees refreshability, the source of authentication value generation in the above process can be the current time information. If the current time information is used, various verification mechanisms utilizing it can be utilized. For example, the verifier can verify whether the received time information is acceptable within a certain error range, and if the received time information is within the acceptable error range, the content of the information can be determined to be valid.

In the above process, the source of authentication value generation can be encrypted using the above-mentioned credential or integrity protected in the form of a message authenticity code.

- Satellite may transmit one or more of the following information to UE:

■ SIG.SAT: Authentication value generated above

■ Nonce: Nonce value included in the PAM held by the Satellite. In this case, the Nonce value included in the PAM may be different for each UE, or may be the same value for all UEs.

At step 1304, one or more of the following processes may be performed:

- The UE may perform one or more of the following processes:

■ The UE can authenticate the satellite by verifying the validity of the received SIG.SAT.

■ The UE can create K _SAT,UE using the K _UE it owns and the information (ID.SAT and/or Nonce) received in step 1.

The UE can generate a value SIG.UE that can verify itself using the above-generated K _SAT,UE .

In the above process, K _SAT,UE may be used as a credential for generating an authentication value, or another value derived from K _SAT,UE may be used.

In the above process, any arbitrary value that guarantees the refreshability of the current session (and can prevent replay attacks) can be used as the source of authentication value generation. As an example of a value that guarantees refreshability, the source of authentication value generation in the above process may be the current time information. If current time information is used, various verification mechanisms utilizing it can be utilized. For example, the verifier can verify whether the received time information is acceptable within a certain error range. If the received time information falls within the acceptable error range, the content of the information can be deemed valid.

In the above process, the source of authentication value generation can be encrypted using the above-mentioned credential or integrity protected in the form of a message authenticity code.

- The UE may transmit one or more of the following information to the Satellite:

■ SIG.UE: Authentication value generated above

■ Satellite can perform one or more of the following processes:

■ The satellite can verify the validity of the SIG.UE transmitted by the UE using the K _SAT,UE acquired above. Through the above process, the satellite can authenticate the terminal.

According to one embodiment, at least one operation illustrated in FIG. 13 can be used in STEP 1 of FIG. 6 or STEP 1 of FIG. 8. According to one embodiment, at least one operation illustrated in FIG. 13 can also be applied to STEP 3 of FIG. 6 or STEP 3 of FIG. 8. According to one embodiment, when at least one operation illustrated in FIG. 13 is applied, some of the operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' already described may be changed as follows. (Operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' that are not described below are identical to operations of 'STEP 3 of FIG. 6 or STEP 3 of FIG. 8' that have already been described.)

[When the embodiment of Fig. 13 is applied to STEP 3 of Fig. 6]

As described above, STEP 3 of FIG. 6 can be composed of the sequential progression of ‘Step 603 of FIG. 6’ and ‘Steps 505 to 509 of FIG. 5’.

According to one embodiment, the disclosure of FIG. 13 can be applied to STEP3 of FIG. 6 in a manner described below.

In one embodiment, step 1 of FIG. 13 may be performed before step 603 of FIG. 6 is executed.

In one embodiment, steps 603 of FIG. 6 and 1302 of FIG. 13 may be combined as follows: The UE may transmit the message described in step 603 of FIG. 6 to the satellite. The UE may further transmit the message described in step 1302 of FIG. 13 to the satellite.

In one embodiment, the operations following step 603 of FIG. 6, step 505 of FIG. 5 and step 1303 of FIG. 13 may be combined as follows: The satellite may transmit the message described in step 505 of FIG. 5 to the UE. The satellite may further transmit the message described in step 1303 of FIG. 13 to the UE. At this time, the message described in step 505 of FIG. 5 may further be included in the source for generating SIG.SAT described in step 1303 of FIG. 13.

In one embodiment, the operations following step 603 of FIG. 6, step 507 of FIG. 5 and step 1304 of FIG. 13, may be combined as follows: The UE may transmit the message described in step 507 of FIG. 5 to the satellite. The UE may further transmit the message described in step 1304 of FIG. 13 to the satellite. At this time, the message described in step 507 of FIG. 5 may further be included in the source for generating SIG.UE described in step 1304 of FIG. 13.

[When the embodiment of Fig. 13 is applied to STEP 3 of Fig. 8]

As described above, STEP 3 of FIG. 8 can be composed of the sequential progression of ‘Step 803 of FIG. 8’ and ‘Steps 707 to 714 of FIG. 7’.

According to one embodiment, the disclosure of FIG. 13 can be applied to STEP3 of FIG. 8 in a manner described below.

In one embodiment, step 1301 of FIG. 13 may be performed before step 803 of FIG. 8 is performed.

In one embodiment, steps 803 of FIG. 8 and 1302 of FIG. 13 may be combined as follows: The UE may transmit the message described in step 803 of FIG. 8 to the satellite. The UE may further transmit the message described in step 1302 of FIG. 13 to the satellite.

In one embodiment, the operations following step 803 of FIG. 8, step 707 of FIG. 7 and step 1303 of FIG. 13 may be combined as follows: The satellite may transmit the message described in step 707 of FIG. 7 to the UE. The satellite may further transmit the message described in step 1303 of FIG. 13 to the UE. At this time, the message described in step 707 of FIG. 7 may further be included in the source for generating SIG.SAT described in step 1303 of FIG. 13.

In one embodiment, the operations following step 803 of FIG. 8, step 709 of FIG. 7 and step 1304 of FIG. 13 may be combined as follows: The UE may transmit the message described in step 709 of FIG. 7 to the satellite. The UE may further transmit the message described in step 1304 of FIG. 13 to the satellite. At this time, the message described in step 709 of FIG. 7 may further be included in the source for generating SIG.UE described in step 1304 of FIG. 13.

FIG. 14 is a diagram showing the configuration of a UE according to one embodiment of the present disclosure.

As illustrated in FIG. 14, the UE of the present disclosure may include a transceiver (1410), a memory (1420), and a processor (1430). The processor (1430), the transceiver (1410), and the memory (1420) of the UE may operate according to the aforementioned UE communication method. However, the components of the UE are not limited to the examples described above. For example, the UE may include more or fewer components than the aforementioned components. In addition, the processor (1430), the transceiver (1410), and the memory (1420) may be implemented in the form of a single chip.

The transceiver (1410) is a general term for the receiver and transmitter of the UE, and can transmit and receive signals with a base station or various network entities. The signals transmitted and received with the base station may include control information and data. To this end, the transceiver (1410) may be configured with an RF (radio frequency) transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-downconverts the received signal. However, this is only an example of the transceiver (1410), and the components of the transceiver (1410) are not limited to the RF transmitter and RF receiver. In addition, the transceiver (1410) may include wired and wireless transceivers, and may include various configurations for transmitting and receiving signals. In addition, the transceiver (1410) may receive a signal through a wireless channel, output it to the processor (1430), and transmit the signal output from the processor (1430) through the wireless channel. Additionally, the transceiver (1410) can receive a communication signal and output it to the processor, and transmit the signal output from the processor to various network entities via a wired or wireless network.

The memory (1420) can store programs and data required for the operation of the UE. In addition, the memory (1420) can store control information or data included in signals acquired from the UE. The memory (1420) can be configured as a storage medium or a combination of storage media, such as a ROM, a RAM, a hard disk, a CD-ROM, and a DVD.

The processor (1430) can control a series of processes so that the UE can operate according to the embodiments of the present disclosure described above. The processor (1430) may include at least one processor. For example, the processor (1430) may include a communication processor (CP) that performs control for communication and an application processor (AP) that controls upper layers such as application programs.

FIG. 15 is a diagram showing the configuration of an entity according to one embodiment of the present disclosure.

As illustrated in FIG. 15, a network entity of the present disclosure may include a transceiver (1510), a memory (1520), and a processor (1530). The processor (1530), the transceiver (1510), and the memory (1520) of the network entity may operate according to the communication method of the network entity described above. However, the components of the network entity are not limited to the examples described above. For example, the network entity may include more or fewer components than the components described above. In addition, the processor (1530), the transceiver (1510), and the memory (1520) may be implemented in the form of a single chip. The network entity may include a Satellite, GN, a base station, or other network devices described above with reference to FIGS. 1 to 13.

The transceiver (1510) is a general term for the receiver and transmitter of a network entity, and can transmit and receive signals with a terminal or other network entities. At this time, the transmitted and received signals may include control information and data. To this end, the transceiver (1510) may be configured with an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and frequency-converts the received signal. However, this is only an example of the transceiver (1510), and the components of the transceiver (1510) are not limited to the RF transmitter and RF receiver. The transceiver (1510) may include wired and wireless transceivers, and may include various configurations for transmitting and receiving signals. In addition, the transceiver (1510) may receive a signal through a communication channel (e.g., a wireless channel) and output it to the processor (1530), and transmit the signal output from the processor (1530) through the communication channel. In addition, the transceiver (1510) may receive a communication signal and output it to the processor, and transmit the signal output from the processor to a terminal or network entity through a wired or wireless network.

The memory (1520) can store programs and data necessary for the operation of the network entity. Furthermore, the memory (1520) can store control information or data included in signals acquired from the network entity. The memory (1520) can be configured as a storage medium, such as a ROM, a RAM, a hard disk, a CD-ROM, a DVD, or a combination of storage media.

The processor (1530) may control a series of processes to enable a network entity to operate according to the embodiments of the present disclosure described above. The processor (1530) may include at least one processor.

It should be noted that the configuration diagrams, exemplary diagrams of control/data signal transmission/reception methods, and exemplary diagrams of operating procedures illustrated in FIGS. 1 to 13 are not intended to limit the scope of the embodiments of the present disclosure. That is, not all components, entities, or operational steps described in FIGS. 1 to 10 should be construed as essential components for the implementation of the disclosure, and implementations may be made within a scope that does not detract from the essence of the disclosure even if only some components are included.

The operations of the embodiments described above can be realized by providing a memory device storing the corresponding program code in any component within the device. That is, the control unit within the device can execute the operations described above by reading and executing the program code stored in the memory device through a processor or a CPU (Central Processing Unit).

The various components and modules of the entity or terminal device described in the present disclosure may be operated using hardware circuits, such as logic circuits based on complementary metal oxide semiconductors, firmware, software, and/or hardware and firmware and/or software embedded in a machine-readable medium. For example, various electrical structures and methods may be implemented using electrical circuits such as transistors, logic gates, and application-specific semiconductors.

The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present disclosure.

These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc-ROMs (CD-ROMs), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or may be stored in memories formed by a combination of some or all of these. In addition, each configuration memory may include multiple copies.

Additionally, the program may be stored on an attachable storage device that is accessible via a communication network, such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed singularly or plurally, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

While the detailed description of this disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the described embodiments, but should be defined not only by the scope of the claims described below, but also by equivalents thereof.

Claims (15)

In a method of operating a UE (user equipment) in a wireless communication system, An operation of receiving a first message from a satellite, the first message including an ID of the satellite and a first random number generated by the satellite for further authentication of the UE and the satellite; An operation of transmitting a second message to the satellite, the second message including the ID of the UE, an authentication value generated by the UE based on the first message, and a second random number generated by the UE for additional authentication of the UE and the satellite; and A method characterized by comprising the action of receiving a third message from the satellite, the third message including an authentication value generated by the satellite based on the second message. In the first paragraph, The first message further includes a Nonce value included in the PAM (partial authentication management) held by the satellite, A method characterized in that the ID of the satellite is an ID used to derive the information of the PAM held by the satellite. In the second paragraph, a step of generating a credential using the ID of the satellite and the Nonce value; and A method characterized by further comprising a step of generating an authentication value of the UE by encrypting the first random number using the credentials. In the third paragraph, A method characterized in that the credentials are acquired from the PAM based on the ID of the UE, and the validity of the authentication value of the UE is verified in the satellite based on the credentials. In a method of operating a satellite in a wireless communication system, An operation of transmitting a first message to the UE, the first message including the ID of the satellite and a first random number generated by the satellite for additional authentication of the UE and the satellite; An operation of receiving a second message from the UE, the second message including the ID of the UE, an authentication value generated by the UE based on the first message, and a second random number generated by the UE for additional authentication of the UE and the satellite; and A method characterized by comprising an action of transmitting a third message including an authentication value generated by the satellite based on the second message to the UE. In paragraph 5, The first message further includes a Nonce value included in the PAM (partial authentication management) held by the satellite, A method characterized in that the ID of the satellite is an ID used to derive the information of the PAM held by the satellite. In the 6th paragraph, a credential is generated using the ID of the satellite and the Nonce value, A method characterized in that the first random number is encrypted using the above credentials and an authentication value of the UE is generated. In paragraph 7, A step of obtaining the credentials from the PAM based on the ID of the UE; and A method characterized by further comprising a step of verifying the validity of the authentication value of the UE based on the credentials. In a wireless communication system, in the UE (user equipment), At least one transceiver; At least one processor communicatively connected to said at least one transceiver; and At least one memory communicatively connected to at least one processor, The at least one memory stores instructions executable, alone or in combination, by the at least one processor, the instructions causing the UE to: Receive a first message from the satellite, including the ID of the satellite and a first random number generated by the satellite for additional authentication of the UE and the satellite, Transmitting a second message to the satellite, the second message including the ID of the UE, an authentication value generated by the UE based on the first message, and a second random number generated by the UE for additional authentication of the UE and the satellite; A UE characterized in that it receives a third message from the satellite, the third message including an authentication value generated by the satellite based on the second message. In paragraph 9, The first message further includes a Nonce value included in the PAM (partial authentication management) held by the satellite, A UE characterized in that the ID of the satellite is an ID used to derive the information of the PAM held by the satellite. In the 10th paragraph, the UE: Generate a credential using the ID of the above satellite and the Nonce value, A UE characterized in that the first random number is encrypted using the credentials to generate an authentication value of the UE. In Article 11, A UE characterized in that the credentials are acquired from the PAM based on the ID of the UE, and the validity of the authentication value of the UE is verified in the satellite based on the credentials. In a satellite in a wireless communication system, At least one transceiver; At least one processor communicatively connected to said at least one transceiver; and At least one memory communicatively connected to at least one processor, The at least one memory stores instructions executable, alone or in combination, by the at least one processor, the instructions causing the satellite to: Transmitting a first message to the UE, including the ID of the satellite and a first random number generated by the satellite for additional authentication of the UE (user equipment) and the satellite, Receive a second message from the UE, including the ID of the UE, an authentication value generated by the UE based on the first message, and a second random number generated by the UE for additional authentication of the UE and the satellite; A satellite characterized in that it transmits a third message including an authentication value generated by the satellite based on the second message to the UE. In Article 13, The first message further includes a Nonce value included in the PAM (partial authentication management) held by the satellite, A satellite characterized in that the ID of the satellite is an ID used to derive information of the PAM possessed by the satellite. In the 14th paragraph, a credential is generated using the ID of the satellite and the Nonce value, A satellite characterized in that the first random number is encrypted using the above credentials and an authentication value of the UE is generated.