Mobile communication system, terminal device, base station device, network device, mobile communication method, and computer program

Abstract

A base station according to the present invention comprises: a base station communication processing unit that uses authenticated encryption to execute processing which relates to encryption and authentication of a message; and a base station control unit that transmits, to a user terminal, authenticated encryption usage method information providing a notification of only encryption of the message, only authentication of the message, or both encryption and authentication of the message, wherein the user terminal is provided with a terminal communication processing unit that uses authenticated encryption to execute processing related to encryption and authentication of a message, and a terminal control unit that determines an authenticated encryption usage method, on the basis of the authenticated encryption usage method information which has been received from the base station.

Description

Mobile communication system, terminal device, base station device, network device, mobile communication method, and computer program

[0001] The present invention relates to a mobile communication system, a terminal device, a base station device, a network device, a mobile communication method, and a computer program. This application claims priority from Japanese Patent Application No. 2025-018961 filed in Japan on February 7, 2025, the content of which is incorporated herein by reference.

[0002] Conventionally, a fifth-generation mobile communication system (5G system) standardized by "3GPP (Registered Trademark) (3rd Generation Partnership Project)" is known (see, for example, Non-Patent Document 1). FIG. 9 is a diagram showing a schematic architecture of a conventional 5G system. In FIG. 9, the 5G system is composed of a UE (User Equipment, user terminal), a RAN (Radio Access Network, radio access network), a UPF (User Plane Function, user plane function) of the CN (Core Network, core network), and various NFs (Network Function, network functions) of the control plane (Control plane: C-plane) of the CN. Examples of the NFs of the C-plane of the CN include an AMF (Access and Mobility Management Function), an SMF (Session Management Function), a PCF (Policy Control Function), a UDM (Unified Data Management), a UDR (Unified Data Repository), and the like.

[0003] As one of the standardizations by 3GPP, there is a specification for encryption and authentication of messages transmitted and received between a UE and a base station (gNB). In this 3GPP specification, the encryption algorithm and the authentication algorithm of the message are provided by separate algorithms.

[0004] Non-patent document 1 describes the security architecture and procedures in a 5G system. Messages transmitted and received in a 5G system are protected by encryption and message authentication. When a message M is sent, the message M is encrypted using "C = ENC_Kenc(M)", and a Message Authentication Code (MAC) T for the message M is generated using "T = MAC_Kint(M)". The encrypted data C and message authentication code T of the message M sent from the sender are decrypted and verified at the receiver.

[0005] The encryption key Kenc used for encrypted data C and the message authentication code key Kint used for message authentication code T are generated according to the key hierarchy shown in Figure 10, for example. Figure 10 is described in "Figure 6.2.2-1" of Non-Patent Literature 1.

[0006] Figure 11 shows the structure of the identifier for the cryptographic algorithm in a conventional 5G system. Figure 11 is described in "5.11.1.1 Ciphering algorithm identifier values" of Non-Patent Literature 1.

[0007] 3GPP, TS 33.501, V18.5.0, 2024-03

[0008] However, the aforementioned 3GPP specification presents challenges in improving processing speed because the message encryption algorithm and authentication algorithm are provided using separate algorithms.

[0009] In contrast, using Authenticated Encryption with Associated Data (AEAD) allows for both message encryption and authentication to be achieved simultaneously, which is expected to contribute to improved processing speed. On the other hand, Authenticated Encryption also allows for providing either message encryption or authentication, but not both. However, the conventional 3GPP specification lacks a mechanism for sharing between the UE and gNB whether to provide only message encryption, only message authentication, or both.

[0010] This invention has been made in consideration of these circumstances, and its purpose is to enable user terminals (UEs) and base stations (gNBs) to share information regarding whether to provide message encryption only, message authentication only, or both message encryption and authentication using authenticated encryption (AEAD).

[0011] One aspect of the present invention is a mobile communication system in which a user terminal and a base station communicate wirelessly, wherein the base station comprises a base station communication processing unit that performs processing related to message encryption and authentication using authenticated encryption, and a base station control unit that transmits authenticated encryption usage method information to the user terminal that notifies either message encryption only, message authentication only, or both message encryption and authentication, and the user terminal comprises a terminal communication processing unit that performs processing related to message encryption and authentication using authenticated encryption, and a terminal control unit that determines how to use authenticated encryption based on the authenticated encryption usage method information received from the base station. One aspect of the present invention is a mobile communication system in which the authenticated encryption usage method information is data of a predetermined bit length and comprises a bit indicating the algorithm of authenticated encryption, a bit indicating whether or not the message is encrypted, and a bit indicating whether or not the message is authenticated. One aspect of the present invention is a mobile communication system in which the authenticated encryption usage method information is data of a predetermined bit length and comprises a bit indicating the algorithm of authenticated encryption and a bit indicating whether or not either the message is encrypted or authenticated. One aspect of the present invention is a mobile communication system in which the authentication encryption method information is data of a predetermined bit length, having a bit indicating the authentication encryption algorithm and a bit indicating whether or not the message is encrypted when notifying the encryption method, and having a bit indicating the authentication encryption algorithm and a bit indicating whether or not the message is authenticated when notifying the message authentication method.

[0012] One aspect of the present invention is a mobile communication system in which a user terminal and a base station communicate wirelessly, comprising a network function unit that transmits authentication-enabled encryption usage method information to the user terminal and the base station, notifying either message encryption only, message authentication only, or both message encryption and authentication; the base station comprising a base station communication processing unit that performs processing related to message encryption and authentication using authentication-enabled encryption, and a base station control unit that determines how to use authentication-enabled encryption based on the authentication-enabled encryption usage method information received from the network function unit; and the user terminal comprising a terminal communication processing unit that performs processing related to message encryption and authentication using authentication-enabled encryption, and a terminal control unit that determines how to use authentication-enabled encryption based on the authentication-enabled encryption usage method information received from the network function unit. Another aspect of the present invention is a mobile communication system in which, in the above mobile communication system, the network function unit is an AMF (Access and Mobility Management Function), and the authentication-enabled encryption usage method information is included in the ABBA (Anti-Bidding down Between Architectures) parameter.

[0013] One aspect of the present invention is a terminal device for a mobile communication system, comprising: a terminal communication processing unit that performs processing related to message encryption and authentication using authenticated encryption; and a terminal control unit that determines how to use authenticated encryption based on authenticated encryption usage method information received from a base station of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication. Another aspect of the present invention is a base station device for a mobile communication system, comprising: a base station communication processing unit that performs processing related to message encryption and authentication using authenticated encryption; and a base station control unit that transmits authenticated encryption usage method information that notifies either message encryption only, message authentication only, or both message encryption and authentication to the terminal device of the mobile communication system.

[0014] One aspect of the present invention is a terminal device for a mobile communication system, comprising: a terminal communication processing unit that performs processing related to message encryption and authentication using authenticated encryption; and a terminal control unit that determines how to use authenticated encryption based on authenticated encryption usage method information received from the network function unit of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication. Another aspect of the present invention is a base station device for a mobile communication system, comprising: a base station communication processing unit that performs processing related to message encryption and authentication using authenticated encryption; and a base station control unit that determines how to use authenticated encryption based on authenticated encryption usage method information received from the network function unit of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication. One aspect of the present invention is a network device for a mobile communication system, comprising a network function unit that transmits authentication-enabled encryption usage method information, which notifies either message encryption only, message authentication only, or both message encryption and authentication, to terminal devices and base station devices of the mobile communication system.

[0015] One aspect of the present invention is a mobile communication method comprising: a terminal communication processing step in which a terminal device of a mobile communication system performs processing related to message encryption and authentication using authenticated encryption; and a terminal control step in which the terminal device determines a method for using authenticated encryption based on authenticated encryption usage method information received from a base station of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication. Another aspect of the present invention is a mobile communication method comprising: a base station communication processing step in which a base station device of a mobile communication system performs processing related to message encryption and authentication using authenticated encryption; and a base station control step in which the base station device transmits authenticated encryption usage method information that notifies either message encryption only, message authentication only, or both message encryption and authentication to a terminal device of the mobile communication system.

[0016] One aspect of the present invention is a computer program that causes a computer in a terminal device of a mobile communication system to execute a terminal communication processing step that performs processing related to message encryption and authentication using authenticated encryption, and a terminal control step that determines how to use authenticated encryption based on authenticated encryption usage method information received from a base station of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication. Another aspect of the present invention is a computer program that causes a computer in a base station device of a mobile communication system to execute a base station communication processing step that performs processing related to message encryption and authentication using authenticated encryption, and a base station control step that transmits authenticated encryption usage method information that notifies either message encryption only, message authentication only, or both message encryption and authentication to a terminal device of the mobile communication system.

[0017] According to the present invention, the user terminal (UE) and the base station (gNB) can share whether to provide message encryption only, message authentication only, or both message encryption and authentication using authenticated encryption (AEAD).

[0018] This figure shows a schematic configuration example of a mobile communication system according to the first embodiment. This figure shows example 1 of authenticated cryptographic usage method information according to the first embodiment. This figure shows example 2 of authenticated cryptographic usage method information according to the first embodiment. This figure shows example 3 of authenticated cryptographic usage method information according to the first embodiment. This figure shows an example of the procedure of a mobile communication method according to the first embodiment. This figure shows a schematic configuration example of a mobile communication system according to the second embodiment. This figure shows an example of the procedure of a mobile communication method according to the second embodiment. This figure shows an example of the key generation process according to the second embodiment. This figure shows a schematic architecture of a conventional 5G system. This figure shows the key hierarchy in a conventional 5G system. This figure shows the configuration of identifiers for cryptographic algorithms in a conventional 5G system.

[0019] Embodiments of the present invention will be described below with reference to the drawings.

[0020] [First Embodiment] Figure 1 is a diagram showing a schematic configuration example of a mobile communication system 1 according to the first embodiment. The mobile communication system 1 may be, for example, a 5G system. The mobile communication system 1 comprises a user terminal (UE) 100 and a base station (gNB) 200. The user terminal 100 and the base station 200 communicate wirelessly. The user terminal 100 corresponds to a terminal device. The base station 200 corresponds to a base station device.

[0021] In this embodiment, authenticated encryption (AEAD) is used to perform either message encryption only, message authentication only, or both message encryption and authentication. To this end, the user terminal (UE) and the base station (gNB) share information on whether authenticated encryption provides message encryption only, message authentication only, or both.

[0022] The user terminal 100 comprises a terminal communication processing unit 110, a wireless unit 120, and a terminal control unit 130. The terminal communication processing unit 110 includes an authentication-encrypted unit 111. The authentication-encrypted unit 111 performs authentication-encrypted processing on messages. Authentication-encrypted processing refers to processing that performs either message encryption only, message authentication only, or both message encryption and authentication using authentication-encrypted encryption.

[0023] The wireless unit 120 transmits and receives data wirelessly to and from the base station 200. Messages that have undergone authentication and encryption processing are transmitted and received between the wireless unit 120 and the base station 200.

[0024] The terminal control unit 130 controls the user terminal 100. Based on the authentication encryption usage method information received from the base station 200, the terminal control unit 130 determines how to use authentication encryption. The authentication encryption usage method is one of the following: message encryption only, message authentication only, or both message encryption and authentication. The authentication encryption unit 111 executes the authentication encryption usage method determined by the terminal control unit 130.

[0025] The base station 200 comprises a base station communication processing unit 210, a radio unit 220, and a base station control unit 230. The base station communication processing unit 210 includes an authenticated encryption unit 211. The authenticated encryption unit 211 performs authenticated encryption processing on messages. Authenticated encryption processing refers to processing that performs either message encryption only, message authentication only, or both message encryption and authentication using authenticated encryption.

[0026] The wireless unit 220 transmits and receives data wirelessly to and from the user terminal 100. Messages that have undergone authentication and encryption processing are transmitted and received between the wireless unit 220 and the user terminal 100.

[0027] The base station control unit 230 controls the base station 200. The base station control unit 230 transmits information on how to use authenticated encryption to the user terminal 100. The method of using authenticated encryption is one of the following: message encryption only, message authentication only, or both message encryption and authentication. The authenticated encryption unit 211 executes the method of using authenticated encryption notified to the user terminal 100 by the base station control unit 230.

[0028] Next, we will explain the authentication-enabled cryptographic usage method information according to the first embodiment, giving some examples.

[0029] [Example 1 of Authenticated Cryptographic Usage Information] As shown in Figure 11, in the configuration of identifiers for cryptographic algorithms in conventional 5G systems, the identifiers for each cryptographic algorithm use 4-bit values ​​"0000 (binary)", "0001 (binary)", "0010 (binary)", and "0011 (binary)". In 5G systems, the cryptographic algorithm used between the UE and the gNB is selected on the network side (e.g., the gNB) according to the "security capability" transmitted from the UE, and notified to the UE.

[0030] In Example 1 of Authenticated Cryptographic Method Information, the Authenticated Cryptographic Method Information is data of a predetermined bit length, comprising bits indicating the algorithm of the authenticated encryption, bits indicating whether or not the message is encrypted, and bits indicating whether or not the message is authenticated.

[0031] Figure 2 shows an example 1 of the authentication encryption method information according to the first embodiment. In the example in Figure 2, the four bits used as the identifier for the encryption algorithm are assigned a bit indicating the authentication encryption algorithm, a bit indicating whether the message is encrypted, and a bit indicating whether the message is authenticated. In the example in Figure 2, the upper two bits of the four bits used as the identifier for the encryption algorithm in the 5G system are assigned a bit indicating the authentication encryption algorithm. The remaining lower two bits are assigned a bit indicating whether the message is encrypted and a bit indicating whether the message is authenticated.

[0032] For example, of the two lower bits, the higher bit indicates whether the message is authenticated (1: ON, 0: OFF), and the lower bit indicates whether the message is encrypted (1: ON, 0: OFF). In this case, for example, the value "0111 (binary)" indicates that both message encryption and authentication are enabled, using authenticated encryption with the "256-bit SNOW 5G based algorithm". Also, the value "0101 (binary)" indicates that message encryption is enabled, but message authentication is not, using authenticated encryption with the "256-bit SNOW 5G based algorithm". Furthermore, the value "0110 (binary)" indicates that message encryption is not enabled, but message authentication is enabled, using authenticated encryption with the "256-bit SNOW 5G based algorithm".

[0033] In conventional 5G systems, four bits are assigned to the identifiers of the message encryption algorithm and the authentication algorithm, and these identifiers are notified separately to the UE. When applying Example 1 of the authentication encryption usage method information to a 5G system, it is sufficient to apply it to the procedure for notifying either the message encryption or authentication identifier.

[0034] [Example 2 of Authenticated Cryptographic Usage Information] In conventional 5G systems, 4 bits are allocated to the identifiers of the message encryption algorithm and authentication algorithm, and these identifiers are notified separately to the UE. In Example 2 of Authenticated Cryptographic Usage Information, by integrating these identifiers, the identifier that previously required 8 bits is compressed to 6 bits, making it possible to notify the authenticated encryption algorithm and the method of using authenticated encryption in a single notification.

[0035] In Example 2 of Authenticated Cryptographic Method Information, the Authenticated Cryptographic Method Information is data of a predetermined bit length, comprising bits indicating the algorithm of the authenticated encryption, bits indicating whether or not the message is encrypted, and bits indicating whether or not the message is authenticated.

[0036] Figure 3 shows an example 2 of the authentication encryption usage method information according to the first embodiment. In the example in Figure 3, of the 6 bits, the upper 4 bits are used to identify the authentication encryption algorithm, and the lower 2 bits are used to identify the authentication encryption usage method. For example, of the lower 2 bits, the upper bit indicates whether the message is authenticated (1: Yes (ON), 0: No (OFF)), and the lower bit indicates whether the message is encrypted (1: Yes (ON), 0: No (OFF)). In this case, for example, the value "000101 (binary)" indicates that authentication encryption using the "256-bit SNOW 5G based algorithm" is used, the message is encrypted, and the message is not authenticated. Also, the value "000110 (binary)" indicates that authentication encryption using the "256-bit SNOW 5G based algorithm" is used, the message is not encrypted, and the message is authenticated. Additionally, the value "000111 (binary)" indicates that the message is encrypted and authenticated, using authenticated encryption based on the "256-bit SNOW 5G based algorithm".

[0037] [Example 3 of Authenticated Cryptography Usage Information] In Example 3 of Authenticated Cryptography Usage Information, the Authenticated Cryptography Usage Information is data of a predetermined bit length, and includes a bit indicating the algorithm of the authenticated encryption and a bit indicating whether or not the message is encrypted or authenticated. For example, the Authenticated Cryptography Usage Information is 4 bits, and includes the upper 3 bits indicating the algorithm of the authenticated encryption and the lower 1 bit indicating whether or not the message is encrypted or authenticated.

[0038] Figure 4 shows an example 3 of the authenticated encryption method information according to the first embodiment. In the example in Figure 4, of the 4 bits, the upper 3 bits are used to identify the authenticated encryption algorithm, and the lower 1 bit is used to identify whether or not the message is encrypted (1: Yes (ON), 0: No (OFF)) in the authenticated encryption method. In this case, for example, the value "0011 (binary)" indicates that authenticated encryption using the "256-bit SNOW 5G based algorithm" is used and the message is encrypted. Also, the value "0010 (binary)" indicates that authenticated encryption using the "256-bit SNOW 5G based algorithm" is used and the message is not encrypted.

[0039] In Example 3 of the Authenticated Encryption Usage Method Information, the Authenticated Encryption Usage Method Information can be used to notify whether a message is encrypted or authenticated, or either one of the other. Therefore, for example, the presence or absence of message authentication can be set to either by default, for example, setting message authentication to "Yes (ON)" by default, and notifying whether a message is encrypted or not using the Authenticated Encryption Usage Method Information shown in Figure 4 above. Note that when message authentication is set to "Yes (ON)" by default, if message authentication is not required, the message recipient should not perform verification of the message authentication code (MAC).

[0040] Furthermore, in the configuration example shown in Figure 4, the most significant bit of the four bits is undefined, which allows for the addition of new algorithms in the future.

[0041] In conventional 5G systems, four bits are assigned to the identifiers of the message encryption algorithm and the authentication algorithm, and these identifiers are notified separately to the UE. When applying Example 3 of the authentication encryption usage method information to a 5G system, it is sufficient to apply it to the procedure for notifying either the message encryption or authentication identifier.

[0042] [Example 4 of Authentication-Enabled Encryption Usage Method Information] In Example 4 of the authentication-enabled encryption usage method information, the presence or absence of message encryption and authentication is separately notified by the authentication-enabled encryption usage method information. Specifically, the authentication-enabled encryption usage method information is data of a predetermined bit length, and when notifying the encryption method, it has a bit indicating the algorithm of the authentication-enabled encryption and a bit indicating the presence or absence of message encryption, and when notifying the message authentication method, it has a bit indicating the algorithm of the authentication-enabled encryption and a bit indicating the presence or absence of message authentication.

[0043] The authentication-enabled encryption usage method information is the same as the configuration example of FIG. 4 in Example 3 of the authentication-enabled encryption usage method information described above. For example, when notifying the encryption method, if the value "0011 (binary)" is used, it is notified that there is message encryption by the authentication-enabled encryption using the "256-bit SNOW 5G based algorithm", and if the value "0010 (binary)" is used, it is notified that there is no message encryption by the authentication-enabled encryption using the "256-bit SNOW 5G based algorithm". On the other hand, when notifying the message authentication method, if the value "0011 (binary)" is used, it is notified that there is message authentication by the authentication-enabled encryption using the "256-bit SNOW 5G based algorithm", and if the value "0010 (binary)" is used, it is notified that there is no message authentication by the authentication-enabled encryption using the "256-bit SNOW 5G based algorithm".

[0044] According to Example 4 of the authentication-enabled encryption usage method information, the presence or absence of message encryption and authentication can be separately notified by the authentication-enabled encryption usage method information. Also, according to the configuration example of FIG. 4, since the uppermost 1 bit out of 4 bits is undefined, it is possible to cope with the addition of a new algorithm in the future.

[0045] In the conventional 5G system, 4 bits are respectively assigned to the identifiers of the message encryption algorithm and the authentication algorithm, and these identifiers are separately notified to the UE. Example 4 of the authenticated encryption usage method information separately notifies the presence or absence of message encryption and authentication by the authenticated encryption usage method information, so it is easy to apply to the conventional 5G system.

[0046] Next, a mobile communication method according to the first embodiment will be described with reference to FIG. 5. FIG. 5 is a diagram showing an example of the procedure of the mobile communication method according to the first embodiment. The procedure of FIG. 5 is a modified example of the procedure ( "Figure 6.6.2-1" in Non-Patent Document 1) regarding the "User plane (UP) security activation mechanism" in the conventional 5G system.

[0047] In the procedure of FIG. 5, the base station 200 (gNB) transmits authenticated encryption usage method information (UP AEAD indication) to the user terminal 100 (UE) in step S1b. The user terminal 100 (UE) determines the authenticated encryption algorithm and the presence or absence of message encryption and authentication based on the authenticated encryption usage method information (UP AEAD indication) received from the base station 200 (gNB). Thereafter, the messages transmitted and received between the user terminal 100 (UE) and the base station 200 (gNB) are processed according to the determined conditions of the authenticated encryption algorithm and the presence or absence of message encryption and authentication.

[0048] According to the first embodiment described above, it is possible to share between the user terminal (UE) and the base station (gNB) which of only message encryption, only message authentication, or both message encryption and authentication is provided by authenticated encryption (AEAD).

[0049] [Second Embodiment] FIG. 6 is a diagram showing a schematic configuration example of a mobile communication system 1a according to the second embodiment. The mobile communication system 1a may be, for example, a 5G system. In FIG. 6, parts corresponding to each part of FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0050] The mobile communication system 1a comprises a user terminal (UE) 100a, a base station (gNB) 200a, and an AMF (Access and Mobility Management Function) 300 (Network Function Unit). The AMF 300 is one of the NFs (Network Functions) of the control plane (C-plane) of the CN (Core Network) of the 5G system. The user terminal 100a corresponds to terminal equipment. The base station 200a corresponds to base station equipment. The AMF 300 corresponds to network equipment.

[0051] The user terminal 100a is equipped with a terminal control unit 130a instead of the terminal control unit 130 in the user terminal 100 of Figure 1. The terminal control unit 130a determines how to use authenticated encryption based on authenticated encryption usage method information received from the AMF 300. Authenticated encryption usage method information is information that notifies how to use authenticated encryption. The method of using authenticated encryption is one of the following: encryption of the message only, authentication of the message only, or both encryption and authentication of the message. The authenticated encryption unit 111 executes the method of using authenticated encryption determined by the terminal control unit 130a.

[0052] Base station 200a is equipped with a base station control unit 230a instead of the base station control unit 230 in Figure 1. The base station control unit 230a determines the method of using authenticated encryption based on authenticated encryption usage method information received from the AMF 300. The authenticated encryption usage method information is information that notifies the method of using authenticated encryption. The method of using authenticated encryption is one of the following: encryption of the message only, authentication of the message only, or both encryption and authentication of the message. The authenticated encryption unit 211 executes the method of using authenticated encryption determined by the base station control unit 230a.

[0053] The AMF300 transmits information on how to use authenticated encryption to the user terminal 100a and the base station 200a. The method of using authenticated encryption is one of the following: message encryption only, message authentication only, or both message encryption and authentication.

[0054] Next, an example of authenticated cryptographic usage method information according to the second embodiment will be described. In conventional 5G systems, a 16-bit ABBA (Anti-Bidding down Between Architectures) parameter is defined to prevent "Bidding Down" attacks (see Non-Patent Literature 1). In Non-Patent Literature 1, only the initial value "0000 (hexadecimal)" is defined for the ABBA parameter, and no other values ​​are defined. Therefore, in the second embodiment, a new value for the ABBA parameter is defined as authenticated cryptographic usage method information, and the ABBA parameter as authenticated cryptographic usage method information is notified from the AMF 300 to the user terminal 100a and the base station 200a.

[0055] Examples of ABBA parameters as authentication-enabled encryption method information are given below. Here, as an example, the following three values ​​"0001 (hexadecimal)", "0002 (hexadecimal)", and "0003 (hexadecimal)" are used as ABBA parameters as authentication-enabled encryption method information. The value "0001 (hexadecimal)" indicates message encryption only. The value "0002 (hexadecimal)" indicates message authentication only. The value "0003 (hexadecimal)" indicates both message encryption and authentication.

[0056] Next, a mobile communication method according to the second embodiment will be described with reference to Figure 7. Figure 7 is a diagram showing an example of the procedure of the mobile communication method according to the second embodiment. The procedure in Figure 7 is a modified version of the procedure related to the "NAS Security Mode Command procedure: NAS SMC" in a conventional 5G system ("Figure 6.7.2-1" in Non-Patent Literature 1).

[0057] In the procedure shown in Figure 7, the AMF 300 transmits ABBA parameters as authenticated encryption method information to the user terminal 100a (UE) in step S1b. Based on the ABBA parameters as authenticated encryption method information received from the AMF 300, the user terminal 100a (UE) determines whether or not to encrypt and authenticate the message.

[0058] Furthermore, in step S1e, the AMF 300 transmits ABBA parameters as authenticated encryption method information to the base station 200a (gNB). Based on the ABBA parameters as authenticated encryption method information received from the AMF 300, the base station 200a (gNB) determines whether or not the message is encrypted and authenticated.

[0059] Furthermore, since the ABBA parameter only notifies the method of using authenticated encryption, the algorithm for authenticated encryption is determined using either the conventional encryption method or the message authentication method.

[0060] From this point forward, messages transmitted and received between the user terminal 100a (UE) and the base station 200a (gNB) are processed according to the determined authenticated encryption algorithm and the conditions for the presence or absence of message encryption and authentication.

[0061] According to the second embodiment described above, authenticated encryption (AEAD) can be used to share between the user terminal (UE) and the base station (gNB) whether to provide message encryption only, message authentication only, or both message encryption and authentication.

[0062] In the second embodiment, the presence or absence of encryption and authentication of the message is indicated by the ABBA parameter. The ABBA parameter is the K in the key hierarchy shown in Figure 10. ＡＭＦ Since it is a parameter used in the derivation of K, ＡＭＦ This affects key generation after the derivation of the formula. This new key generation process is shown in Figure 8. Figure 8 shows only the changes from Figure 10. Here, according to this embodiment, since authenticated encryption is used, it is possible to combine the keys that were conventionally generated separately for message encryption and authentication into one, thereby simplifying the key generation process.

[0063] Furthermore, this will enable improvements in overall service quality, such as in mobile communication systems, and will contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs): "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0064] Although embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and design modifications and the like are also included within the scope of the gist of the present invention.

[0065] Alternatively, computer programs for realizing the functions of each of the above-mentioned devices may be recorded on a computer-readable recording medium, and the programs recorded on this recording medium may be loaded into a computer system and executed. The term "computer system" here may include hardware such as an operating system and peripheral devices. Furthermore, "computer-readable recording medium" refers to writable non-volatile memory such as flexible disks, magneto-optical disks, ROMs, and flash memory, portable media such as DVDs (Digital Versatile Discs), and storage devices such as hard disks built into a computer system.

[0066] Furthermore, "computer-readable recording media" includes volatile memory (e.g., DRAM (Dynamic Random Access Memory)) within a computer system that acts as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, which retains the program for a certain period of time. In addition, the above program may be transmitted from the computer system that stores the program in a storage device, etc., to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium that has the function of transmitting information, such as a network such as the Internet or a communication line such as a telephone line. Furthermore, the above program may be for the purpose of realizing a part of the above-mentioned functions. In addition, it may be a so-called differential file (differential program) that can realize the above-mentioned functions in combination with a program already recorded in the computer system.

[0067] According to the present invention, authentication-encrypted encryption allows the user terminal and the base station to share information about whether to provide message encryption only, message authentication only, or both message encryption and authentication.

[0068] 1, 1a...Mobile communication system, 100, 100a...User terminal (UE), 110...Terminal communication processing unit, 120...Wireless unit, 130, 130a...Terminal control unit, 111, 211...Authentication-enabled encryption unit, 200, 200a...Base station (gNB), 210...Base station communication processing unit, 220...Wireless unit, 230, 230a...Base station control unit, 300...AMF

Claims

1. A mobile communication system in which a user terminal and a base station communicate wirelessly, wherein the base station comprises a base station communication processing unit that performs processing related to message encryption and authentication using authenticated encryption, and a base station control unit that transmits authenticated encryption usage method information to the user terminal that notifies either message encryption only, message authentication only, or both message encryption and authentication, and the user terminal comprises a terminal communication processing unit that performs processing related to message encryption and authentication using authenticated encryption, and a terminal control unit that determines how to use authenticated encryption based on the authenticated encryption usage method information received from the base station, 2. The mobile communication system according to claim 1, wherein the authentication encryption method information is data of a predetermined bit length, comprising a bit indicating the authentication encryption algorithm, a bit indicating whether or not the message is encrypted, and a bit indicating whether or not the message is authenticated.

3. The mobile communication system according to claim 1, wherein the authentication encryption method information is data of a predetermined bit length, comprising a bit indicating the authentication encryption algorithm and a bit indicating whether or not the message is encrypted or authenticated.

4. The mobile communication system according to claim 1, wherein the authentication encryption method information is data of a predetermined bit length, and when notifying the encryption method, it has a bit indicating the algorithm of the authentication encryption and a bit indicating whether or not the message is encrypted, and when notifying the message authentication method, it has a bit indicating the algorithm of the authentication encryption and a bit indicating whether or not the message is authenticated.

5. A mobile communication system in which a user terminal and a base station communicate wirelessly, comprising: a network function unit that transmits authentication-enabled encryption usage method information to the user terminal and the base station, notifying either message encryption only, message authentication only, or both message encryption and authentication; the base station comprising: a base station communication processing unit that performs processing related to message encryption and authentication using authentication-enabled encryption; and a base station control unit that determines how to use authentication-enabled encryption based on the authentication-enabled encryption usage method information received from the network function unit; and the user terminal comprising: a terminal communication processing unit that performs processing related to message encryption and authentication using authentication-enabled encryption; and a terminal control unit that determines how to use authentication-enabled encryption based on the authentication-enabled encryption usage method information received from the network function unit.

6. The mobile communication system according to claim 5, wherein the network function unit is an AMF (Access and Mobility Management Function), and the authenticated cryptographic usage method information is included in the ABBA (Anti-Bidding down Between Architectures) parameters.

7. A terminal device of a mobile communication system comprising: a terminal communication processing unit that performs processing related to message encryption and authentication using authenticated encryption; and a terminal control unit that determines how to use authenticated encryption based on authenticated encryption usage method information received from a base station of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication.

8. A base station device of a mobile communication system comprising: a base station communication processing unit that performs processing related to message encryption and authentication using authenticated encryption; and a base station control unit that transmits authenticated encryption usage method information to a terminal device of the mobile communication system, notifying either message encryption only, message authentication only, or both message encryption and authentication.

9. A terminal device of a mobile communication system comprising: a terminal communication processing unit that performs processing related to message encryption and authentication using authenticated encryption; and a terminal control unit that determines how to use authenticated encryption based on authenticated encryption usage method information received from the network function unit of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication.

10. A base station device of a mobile communication system comprising: a base station communication processing unit that performs processing related to message encryption and authentication using authenticated encryption; and a base station control unit that determines how to use authenticated encryption based on authenticated encryption usage method information received from the network function unit of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication.

11. Network device of a mobile communication system, comprising a network function unit that transmits authentication-enabled encryption usage method information to terminal devices and base station devices of the mobile communication system, which notifies either message encryption only, message authentication only, or both message encryption and authentication.

12. A mobile communication method comprising: a terminal communication processing step in which a terminal device of a mobile communication system performs processing related to message encryption and authentication using authenticated encryption; and a terminal control step in which the terminal device determines a method for using authenticated encryption based on authenticated encryption usage method information received from a base station of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication.

13. A mobile communication method comprising: a base station communication processing step in which a base station device of a mobile communication system performs processing related to message encryption and authentication using authenticated encryption; and a base station control step in which the base station device transmits authenticated encryption usage method information to a terminal device of the mobile communication system, notifying either message encryption only, message authentication only, or both message encryption and authentication.

14. A computer program for causing a computer in a terminal device of a mobile communication system to execute a terminal communication processing step that performs processing related to message encryption and authentication using authenticated encryption, and a terminal control step that determines how to use authenticated encryption based on authenticated encryption usage method information received from a base station of the mobile communication system, wherein the authenticated encryption usage method information is information that notifies either message encryption only, message authentication only, or both message encryption and authentication.

15. A computer program for causing the computer of a base station device of a mobile communication system to execute a base station communication processing step that performs processing related to message encryption and authentication using authenticated encryption, and a base station control step that transmits authenticated encryption usage method information notifying one of the following to a terminal device of the mobile communication system: message encryption only, message authentication only, or both message encryption and authentication.

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