Method for user authentication by applying pre-shared key to base selection in quantum communication system and apparatus therefor

Abstract

The present specification provides a method for user authentication in a quantum communication system. More specifically, the method comprises the steps of: generating authentication quantum information by encoding an authentication message for user authentication on the basis of a pre-shared key, in which a basis for encoding each bit element constituting the authentication message is determined on the basis of a corresponding bit value of the bit element constituting the pre-shared key, the respective bit elements correspond to respective positions of the bit elements constituting the pre-shared key; sending authentication quantum information to a receiving end via a quantum channel; receiving, from the receiving end, authentication quantum information measurement information relating to a value obtained by measuring the authentication quantum information by means of the receiving end; and performing user authentication with the receiving end based on the authentication quantum information measurement information.

Description

Technical Field

[0001] The present disclosure relates to a quantum communication system, and more particularly, to a method and apparatus for user authentication in a quantum communication system. Background Art

[0002] Wireless communication systems have been widely deployed to provide various types of communication services, such as voice or data. Generally, a wireless communication system is a multi-access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multi-access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, space division multiple access (SDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and interleaved division multiple access (IDMA) systems. In addition, research on quantum communication, which is a next-generation communication technology that can overcome the limitations of existing information and communication (such as security and high-speed computing) by applying quantum mechanical properties to the field of information and communication, is continuing. Different from existing communication based on binary bit information, quantum communication provides a means to generate, transmit, process, and store information in the superposition of 0 and 1. In existing communication technologies, wavelength or amplitude is used to transmit information between a transmitting end and a receiving end, while in quantum communication, photons, which are the smallest units of light, are used to transmit information between a transmitting end and a receiving end. Summary of the Invention

[0003] Technical Problem

[0004] One aspect of the present disclosure is to provide a method and apparatus for user authentication in a quantum direct communication system.

[0005] In addition, one aspect of the present disclosure is to provide a method and apparatus for authentication based on a pre-shared key pre-shared between a transmitting end and a receiving end.

[0006] In addition, one aspect of the present disclosure is to provide a method and apparatus that solve the problem of loss of transmitted information caused by a mismatch between the bases used by the transmitting end and the receiving end when authentication is performed between the transmitting end and the receiving end.

[0007] In addition, one aspect of the present disclosure is to provide a method and apparatus that perform user authentication without a separate error correction process when the authentication codes of the transmitting end and the receiving end do not match due to a channel error when authentication is performed between the transmitting end and the receiving end.

[0008] The technical objectives of the present disclosure are not limited to the foregoing technical objectives, and other technical objectives not mentioned above will be apparent to those of ordinary skill in the art from the following description.

[0009] Technical solution

[0010] The present disclosure provides a method and an apparatus for performing user authentication in a quantum communication system.

[0011] More specifically, a method for performing user authentication at a sending end in a quantum communication system according to an embodiment of the present disclosure includes the following steps: generating authentication quantum information by encoding an authentication message for user authentication based on a pre-shared key, wherein a basis for encoding each bit element constituting the authentication message is determined based on a corresponding bit value of a bit element constituting the pre-shared key, and the corresponding bit element corresponds to a corresponding position of the bit element constituting the pre-shared key; sending the authentication quantum information to a receiving end via a quantum channel; receiving authentication quantum information measurement information related to a value obtained by the receiving end by measuring the authentication quantum information; and performing user authentication with the receiving end based on the authentication quantum information measurement information.

[0012] The length of the pre-shared key and the length of the authentication message for user authentication may be equal.

[0013] The pre-shared key may be used to determine a basis used by the receiving end to measure the authentication quantum information.

[0014] The success of the user authentication may be determined based on an error rate between (i) a value of the authentication message generated by the sending end and (ii) a value of the authentication quantum information measurement information obtained by the sending end.

[0015] The success of the user authentication may be determined based on a comparison result between (i) an error rate between a value of the authentication message generated by the sending end and a value of the authentication quantum information measurement information obtained by the sending end and (ii) a threshold for determining the success of the user authentication.

[0016] Based on that (i) the error rate between a value of the authentication message generated by the sending end and a value of the authentication quantum information measurement information obtained by the sending end is lower than (ii) the threshold for determining the success of the user authentication, the user authentication may succeed.

[0017] Based on that (i) the error rate between a value of the authentication message generated by the sending end and a value of the authentication quantum information measurement information obtained by the sending end is equal to or higher than (ii) the threshold for determining the success of the user authentication, the user authentication may fail.

[0018] The QBER (Quantum Bit Error Rate) threshold for QBER estimation for determining the presence of an eavesdropper on the quantum channel can be used as the threshold for determining the success of user authentication.

[0019] The method may further include the step of: based on the success of the user authentication, sending a secret key to the receiving end for encrypting classical information transmitted via a classical channel.

[0020] The method may further include the steps of: encrypting the classical information based on the secret key; and transmitting the encrypted classical information to the receiving end via the classical channel.

[0021] A transmitting end for user authentication in a quantum communication system according to another embodiment of the present disclosure includes: a transmitter for transmitting a wireless signal; a receiver for receiving a wireless signal; at least one processor; and at least one computer memory operatively connectable to the at least one processor and storing instructions that, when executed by the at least one processor, perform operations. The operations include: generating authentication quantum information by encoding an authentication message for user authentication based on a pre-shared key, wherein the basis for encoding each bit element constituting the authentication message is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key; transmitting the authentication quantum information to a receiving end via a quantum channel; receiving authentication quantum information measurement information related to a value obtained by measuring the authentication quantum information by the receiving end; and performing user authentication with the receiving end based on the authentication quantum information measurement information.

[0022] A method for user authentication at a receiving end in a quantum communication system according to another embodiment of the present disclosure includes the following steps: receiving, from a sending end, authentication quantum information generated by encoding an authentication message for user authentication based on a pre-shared key, wherein a basis for encoding each bit element constituting the authentication message is determined based on a corresponding bit value of a bit element constituting the pre-shared key, and the corresponding bit element corresponds to a corresponding position of the bit element constituting the pre-shared key; receiving the authentication quantum information from the sending end via a quantum channel; measuring the received authentication quantum information based on the pre-shared key, wherein a measurement basis for measuring each bit element constituting the received authentication quantum information is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to a corresponding position of the bit element constituting the pre-shared key; sending, to the sending end, authentication quantum information measurement information related to a value obtained by measuring the authentication quantum information by means of the receiving end; and performing user authentication with the sending end based on the authentication quantum information measurement information.

[0023] A receiving end for user authentication in a quantum communication system according to another embodiment of the present disclosure includes: a transmitter configured to send wireless signals; a receiver configured to receive wireless signals; at least one processor; and at least one computer memory operatively connectable to the at least one processor and storing instructions that, when executed by the at least one processor, perform operations. The operations include: receiving, from a sending end, authentication quantum information generated by encoding an authentication message for user authentication based on a pre-shared key, wherein a basis for encoding each bit element constituting the authentication message is determined based on a corresponding bit value of a bit element constituting the pre-shared key, and the corresponding bit element corresponds to a corresponding position of the bit element constituting the pre-shared key; receiving the authentication quantum information from the sending end via a quantum channel; measuring the received authentication quantum information based on the pre-shared key, wherein a measurement basis for measuring each bit element constituting the received authentication quantum information is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to a corresponding position of the bit element constituting the pre-shared key; sending, to the sending end, authentication quantum information measurement information related to a value obtained by measuring the authentication quantum information by means of the receiving end; and performing user authentication with the sending end based on the authentication quantum information measurement information.

[0024] A non-transitory computer-readable medium (CRM) storing one or more instructions according to another embodiment of the present disclosure, the one or more instructions being executable by one or more processors and including: generating authentication quantum information by encoding an authentication message for user authentication based on a pre-shared key, wherein a basis for encoding each bit element constituting the authentication message is determined based on a corresponding bit value of a bit element constituting the pre-shared key, and the corresponding bit element corresponds to a corresponding position of the bit element constituting the pre-shared key; transmitting the authentication quantum information to a receiving end via a quantum channel; receiving authentication quantum information measurement information related to a value obtained by measuring the authentication quantum information by the receiving end; and performing user authentication with the receiving end based on the authentication quantum information measurement information.

[0025] An apparatus according to another embodiment of the present disclosure includes one or more memories and one or more processors functionally connected to the one or more memories. The one or more processors control the apparatus to: generate authentication quantum information by encoding an authentication message for user authentication based on a pre-shared key, wherein a basis for encoding each bit element constituting the authentication message is determined based on a corresponding bit value of a bit element constituting the pre-shared key, and the corresponding bit element corresponds to a corresponding position of the bit element constituting the pre-shared key; transmit the authentication quantum information to a receiving end via a quantum channel; receive authentication quantum information measurement information related to a value obtained by measuring the authentication quantum information by the receiving end; and perform user authentication with the receiving end based on the authentication quantum information measurement information.

[0026] Advantageous effects

[0027] The present disclosure has the effect of performing user authentication in a quantum communication system.

[0028] In addition, the present disclosure has the effect of performing authentication based on a pre-shared key pre-shared between a sending end and a receiving end.

[0029] In addition, the present disclosure has the effect of reducing information loss available for user authentication caused by a mismatch between bases used by a sending end and a receiving end when performing authentication between the sending end and the receiving end.

[0030] In addition, the present disclosure has the effect of reducing the complexity of the overall user authentication process, because when performing authentication between a sending end and a receiving end, if the authentication codes of the sending end and the receiving end do not match due to a channel error, user authentication can be performed without a separate error correction process.

[0031] The advantages obtainable in the present disclosure are not limited to the foregoing effects, and those skilled in the art will clearly understand other unmentioned effects from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are provided to assist in understanding the present disclosure, and the embodiments of the present disclosure may be provided together with the detailed description. However, the technical features of the present disclosure are not limited to specific drawings, and the features disclosed in each drawing may be combined with each other to form new embodiments. The reference numerals in each drawing may refer to structural elements.

[0033] Figure 1 is a diagram showing an example of a communication system applicable to the present disclosure.

[0034] Figure 2 is a diagram showing an example of a wireless device applicable to the present disclosure.

[0035] Figure 3 is a diagram showing a method of processing a transmission signal applicable to the present disclosure.

[0036] Figure 4 is a diagram showing another example of a wireless device applicable to the present disclosure.

[0037] Figure 5 is a diagram showing an example of a handheld device applicable to the present disclosure.

[0038] Figure 6 is a diagram showing a physical channel applicable to the present disclosure and a signal transmission method using the physical channel.

[0039] Figure 7 is a diagram showing the structure of a radio frame applicable to the present disclosure.

[0040] Figure 8 is a diagram showing the structure of a time slot applicable to the present disclosure.

[0041] Figure 9 is a diagram showing an example of a communication structure that can be provided in a 6G system applicable to the present disclosure.

[0042] Figure 10 is a diagram showing an example of a quantum coding communication system applying QKD.

[0043] Figure 11 is a diagram showing an example of a man-in-the-middle attack that may occur in quantum communication.

[0044] Figure 12 is a diagram showing an example of an MAC-based authentication technique.

[0045] Figure 13It is a diagram showing an example of an authentication scheme based on Wegman & Carter authentication (WCA).

[0046] Figure 14 It is a diagram for describing the correlation between the number of hash functions and the collision probability.

[0047] Figure 15 It is a diagram showing an example of quantum authentication information transmission and reception based on random basis selection in an existing quantum communication method.

[0048] Figure 16 It is a diagram showing an example of a user authentication technique that uses a pre-shared key to match the bases used by a sender and a receiver in an ideal situation where no channel error occurs.

[0049] Figure 17 It is a diagram showing another example of a user authentication technique that uses a pre-shared key to match the bases used by a sender and a receiver in an environment where noise such as a channel error actually exists.

[0050] Figure 18 It is a flowchart showing the overall process of a user authentication scheme that uses a pre-shared key for basis selection proposed in the present disclosure.

[0051] Figure 19 It is a diagram showing an example of a quantum coding communication system including a user authentication method that uses a pre-shared key for basis selection.

[0052] Figure 20 It is a flowchart showing an example of a QKD system including a user authentication process based on a pre-shared key and a pre-shared key update method.

[0053] Figure 21 It is a flowchart showing an example of the user authentication method proposed in the present disclosure performed by a sender.

[0054] Figure 22 It is a flowchart showing an example of the user authentication method proposed in the present disclosure performed by a receiver. Detailed implementation manners

[0055] The embodiments of the present disclosure described below are combinations of elements and features of specific forms of the present disclosure. Unless otherwise stated, an element or feature can be considered optional. Each element or feature can be practiced without being combined with other elements or features. In addition, embodiments of the present disclosure can be constructed by combining some of the elements and / or features. The order of operations described in the embodiments of the present disclosure can be rearranged. Some configurations or elements of any one embodiment can be included in another embodiment and can be replaced with corresponding configurations or features of another embodiment.

[0056] In the description of the drawings, processes or steps that would unnecessarily obscure the scope of the present disclosure will be omitted, and processes or steps that can be understood by those skilled in the art will be omitted.

[0057] Throughout the specification, when a part "includes" or "contains" a certain component, this indicates that other components are not excluded, and other components can also be included unless otherwise stated. The terms "unit", "device", and "module" described in the specification indicate a unit for processing at least one function or operation, which can be implemented by hardware, software, or a combination thereof. In addition, terms such as "one or a", "a", "the", etc. in the context of the present disclosure (more specifically, in the context of the appended claims) can include singular representations and plural representations unless otherwise indicated in the specification or unless the context clearly indicates otherwise.

[0058] In the embodiments of the present disclosure, the data transmission and reception relationship between a base station (BS) and a mobile station is mainly described. The BS refers to the terminal node of the network that directly communicates with the mobile station. Specific operations described as being performed by the BS can be performed by an upper-layer node of the BS.

[0059] That is, it is obvious that in a network composed of multiple network nodes including the BS, various operations performed to communicate with the mobile station can be performed by the BS or network nodes other than the BS. The term "BS" can be replaced with a fixed station, Node B, evolved Node B (eNode B or eNB), advanced base station (ABS), access point, etc.

[0060] In the embodiments of the present disclosure, the term terminal can be replaced with UE, mobile station (MS), subscriber station (SS), mobile subscriber station (MSS), mobile terminal, advanced mobile station (AMS), etc.

[0061] The sender is a fixed and / or mobile node that provides data services or voice services, and the receiver is a fixed and / or mobile node that receives data services or voice services. Thus, on the uplink (UL), the mobile station can act as the sender, and the BS can act as the receiver. Similarly, on the downlink (DL), the mobile station can act as the receiver, and the BS can act as the sender.

[0062] Embodiments of the present disclosure may be supported by standard specifications disclosed for at least one of wireless access systems including Institute of Electrical and Electronics Engineers (IEEE) 802xx systems, 3rd Generation Partnership Project (3GPP) systems, 3GPP Long Term Evolution (LTE) systems, 3GPP 5th Generation (5G) New Radio (NR) systems, and 3GPP2 systems. Specifically, embodiments of the present disclosure may be supported by standard specifications 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.321, and 3GPP TS 36.331.

[0063] In addition, embodiments of the present disclosure are applicable to other radio access systems and are not limited to the above systems. For example, embodiments of the present disclosure are applicable to systems applied after the 3GPP 5G NR system and are not limited to a specific system.

[0064] That is, these documents may support steps or parts not described to clarify the technical features of the present disclosure. In addition, all terms described herein may be interpreted by standard documents.

[0065] Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The detailed description given below with reference to the accompanying drawings is intended to explain the exemplary embodiments of the present disclosure and not to show the only embodiments that can be implemented according to the present disclosure.

[0066] The following detailed description includes specific terms to provide a thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that the specific terms may be replaced with other terms without departing from the technical spirit and scope of the present disclosure.

[0067] Embodiments of the present disclosure may be applied to various radio access systems, such as Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), etc.

[0068] In the following, for the purpose of clarifying the following description, the description is based on a 3GPP communication system (e.g., LTE, NR, etc.), but the technical spirit of the present disclosure is not limited thereto. LTE may refer to the technology after Release 8 of 3GPP TS 36.xxx. Specifically, the LTE technology after Release 10 of 3GPP TS 36.xxx may be referred to as LTE-A, and the LTE technology after Release 13 of 3GPP TS 36.xxx may be referred to as LTE-A pro. 3GPP NR may refer to the technology after Release 15 of TS 38.xxx. 3GPP 6G may be referred to as Technical Standard Version 17 and / or Version 18. "xxx" may refer to the detailed number of the standard document. LTE / NR / 6G may be collectively referred to as the 3GPP system.

[0069] Regarding the background art, the terms, abbreviations, etc. used in the present disclosure refer to the content described in the standard documents published before the present disclosure. For example, reference may be made to the standard documents 36.xxx and 38.xxx.

[0070] Communication systems applicable to the present disclosure

[0071] Without limitation, the various descriptions, functions, processes, proposals, methods, and / or operation flowcharts disclosed herein are applicable to various fields (e.g., 5G) that require wireless communication / connection.

[0072] In the following, a more detailed description will be given with reference to the accompanying drawings. In the following drawings / description, the same reference numerals may illustrate the same or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise specified.

[0073] Figure 1 is a diagram showing an example of a communication system applicable to the present disclosure. Refer to Figure 1, the communication system 100 applicable to the present disclosure includes wireless devices, base stations, and a network. A wireless device refers to a device used to perform communication using radio access technology (e.g., 5G NR or LTE), and can be referred to as a communication / wireless / 5G device. Without limitation, the wireless devices may include a robot 100a, vehicles 100b-1 and 100b-2, an extended reality (XR) device 100c, a handheld device 100d, a household appliance 100e, an Internet of Things (IoT) device 100f, and an artificial intelligence (AI) device / server 100g. For example, a vehicle may include a vehicle with a wireless communication function, an autonomous driving vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Vehicles 100b-1 and 100b-2 may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device 100c includes an augmented reality (AR) / virtual reality (VR) / mixed reality (MR) device, and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) installed in a vehicle, a television, a smart phone, a computer, a wearable device, a household appliance, a digital sign, a vehicle, or a robot. The handheld device 100d may include a smart phone, a smart board, a wearable device (e.g., a smart watch or smart glasses), a computer (e.g., a laptop computer), etc. The household appliance 100e may include a television, a refrigerator, a washing machine, etc. The IoT device 100f may include a sensor, a smart meter, etc. For example, the base station 120 and the network 130 may be implemented by a wireless device, and a specific wireless device 120a may operate as a base station / network node for another wireless device.

[0074] The wireless devices 100a to 100f may be connected to the network 130 through the base station 120. AI technology is applicable to the wireless devices 100a to 100f, and the wireless devices 100a to 100f may be connected to the AI server 100g through the network 130. The network 130 may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network, etc. The wireless devices 100a to 100f may communicate with each other through the base station 120 / network 130, or perform direct communication (e.g., sidelink communication) without passing through the base station 120 / network 130. For example, vehicles 100b-1 and 100b-2 may perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). In addition, the IoT device 100f (e.g., a sensor) may perform direct communication with another IoT device (e.g., a sensor) or other wireless devices 100a to 100f.

[0075] Wireless communications / connections 150a, 150b, and 150c can be established between wireless devices 100a to 100f / base station 120 and base station 120 / base station 120. Here, the wireless communications / connections can be established through various radio access technologies (e.g., 5G NR), such as uplink / downlink communication 150a, sidelink communication 150b (or D2D communication), or communication 150c between base stations (e.g., relay, integrated access backhaul (IAB)). The wireless device and the base station / wireless device or the base station and the base station can send / receive radio signals to / from each other through the wireless communications / connections 150a, 150b, and 150c. For example, the wireless communications / connections 150a, 150b, and 150c can implement signal transmission / reception through various physical channels. To this end, based on various proposals of the present disclosure, at least some of various configuration information setting processes, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), resource allocation processes, etc. for the transmission / reception of radio signals can be performed.

[0076] A communication system applicable to the present disclosure

[0077] Figure 2 is a diagram showing an example of a wireless device applicable to the present disclosure.

[0078] Reference Figure 2 , the first wireless device 200a and the second wireless device 200b can send and receive wireless signals through various radio access technologies (e.g., LTE or NR). Here, {the first wireless device 200a, the second wireless device 200b} can correspond to Figure 1 {wireless device 100x, base station 120} and / or {wireless device 100x, wireless device 100x}.

[0079] The first wireless device 200a may include one or more processors 202a and one or more memories 204a, and may further include one or more transceivers 206a and / or one or more antennas 208a. The processor 202a may be configured to control the memory 204a and / or the transceiver 206a, and implement the descriptions, functions, processes, proposals, methods, and / or operation flowcharts disclosed herein. For example, the processor 202a may process the information in the memory 204a to generate first information / signals, and then transmit radio signals including the first information / signals through the transceiver 206a. Additionally, the processor 202a may receive radio signals including second information / signals through the transceiver 206a, and then store the information obtained from the signal processing of the second information / signals in the memory 204a. The memory 204a may be connected to the processor 202a and store various information related to the operation of the processor 202a. For example, the memory 204a may store software code that includes instructions for executing all or some of the processes controlled by the processor 202a or for implementing the descriptions, functions, processes, proposals, methods, and / or operation flowcharts disclosed herein. Here, the processor 202a and the memory 204a may be part of a communication modem / circuit / chip designed to implement wireless communication technologies (e.g., LTE or NR). The transceiver 206a may be connected to the processor 202a to transmit and / or receive radio signals through one or more antennas 208a. The transceiver 206a may include a transmitter and / or a receiver. The transceiver 206a may be used interchangeably with a radio frequency (RF) unit. In the present disclosure, a wireless device may refer to a communication modem / circuit / chip.

[0080] The second wireless device 200b may include one or more processors 202b and one or more memories 204b, and may further include one or more transceivers 206b and / or one or more antennas 208b. The processor 202b may be configured to control the memory 204b and / or the transceiver 206b, and implement the descriptions, functions, processes, proposals, methods, and / or operation flowcharts disclosed herein. For example, the processor 202b may process the information in the memory 204b to generate third information / signals, and then transmit the third information / signals through the transceiver 206b. Additionally, the processor 202b may receive a radio signal including fourth information / signals through the transceiver 206b, and then store the information obtained from the signal processing of the fourth information / signals in the memory 204b. The memory 204b may be connected to the processor 202b to store various information related to the operation of the processor 202b. For example, the memory 204b may store software code that includes instructions for executing all or some of the processes controlled by the processor 202b or for implementing the descriptions, functions, processes, proposals, methods, and / or operation flowcharts disclosed herein. Herein, the processor 202b and the memory 204b may be part of a communication modem / circuit / chip designed to implement wireless communication technologies (e.g., LTE or NR). The transceiver 206b may be connected to the processor 202b to transmit and / or receive radio signals through one or more antennas 208b. The transceiver 206b may include a transmitter and / or a receiver. The transceiver 206b may be used interchangeably with a radio frequency (RF) unit. In this disclosure, a wireless device may refer to a communication modem / circuit / chip.

[0081] In the following, the hardware components of the wireless devices 200a and 200b will be described in more detail. Without being limited thereto, one or more protocol layers may be implemented by one or more processors 202a and 202b. For example, one or more processors 202a and 202b may implement one or more layers (e.g., functional layers such as PHY (Physical), MAC (Media Access Control), RLC (Radio Link Control), PDCP (Packet Data Convergence Protocol), RRC (Radio Resource Control), SDAP (Service Data Adaptation Protocol)). One or more processors 202a and 202b may generate one or more protocol data units (PDUs) and / or one or more service data units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed herein. One or more processors 202a and 202b may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed herein. One or more processors 202a and 202b may generate PDUs, SDUs, messages, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed herein, and provide the PDUs, SDUs, messages, control information, data, or information to one or more transceivers 206a and 206b. One or more processors 202a and 202b may receive signals (e.g., baseband signals) from one or more transceivers 206a and 206b, and obtain PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or operation flowcharts disclosed herein.

[0082] One or more processors 202a and 202b may be referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more processors 202a and 202b may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in one or more processors 202a and 202b. The descriptions, functions, processes, proposals, methods, and / or operational flowcharts disclosed herein may be implemented using firmware or software, and the firmware or software may be implemented to include modules, processes, functions, etc. The firmware or software configured to execute the descriptions, functions, processes, proposals, methods, and / or operational flowcharts disclosed herein may be included in one or more processors 202a and 202b, or stored in one or more memories 204a and 204b to be driven by one or more processors 202a and 202b. The descriptions, functions, processes, proposals, methods, and / or operational flowcharts disclosed herein are implemented using firmware or software in the form of code, commands, and / or command sets.

[0083] One or more memories 204a and 204b may be connected to one or more processors 202a and 202b to store various types of data, signals, messages, information, programs, code, instructions, and / or commands. One or more memories 204a and 204b may be composed of read only memory (ROM), random access memory (RAM), erasable programmable read only memory (EPROM), flash memory, hard disk drive, registers, cache memory, computer readable storage medium, and / or a combination thereof. One or more memories 204a and 204b may be located inside and / or outside one or more processors 202a and 202b. Additionally, one or more memories 204a and 204b may be connected to one or more processors 202a and 202b through various technologies such as wired connection or wireless connection.

[0084] One or more transceivers 206a and 206b may send user data, control information, radio signals / channels, etc. described in the methods and / or operational flowcharts of the present disclosure to one or more other devices. One or more transceivers 206a and 206b may receive user data, control information, radio signals / channels, etc. described in the methods and / or operational flowcharts of the present disclosure from one or more other devices. For example, one or more transceivers 206a and 206b may be connected to one or more processors 202a and 202b to send / receive radio signals. For example, one or more processors 202a and 202b may perform control to cause one or more transceivers 206a and 206b to send user data, control information, or radio signals to one or more other devices. Additionally, one or more processors 202a and 202b may perform control to cause one or more transceivers 206a and 206b to receive user data, control information, or radio signals from one or more other devices. Additionally, one or more transceivers 206a and 206b may be connected to one or more antennas 208a and 208b, and one or more transceivers 206a and 206b may be configured to send / receive user data, control information, radio signals / channels, etc. described in the descriptions, functions, processes, proposals, methods, and / or operational flowcharts disclosed herein through one or more antennas 208a and 208b. In the present disclosure, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers 206a and 206b may convert received radio signals / channels, etc. from RF band signals to baseband signals for processing received user data, control information, radio signals / channels, etc. using one or more processors 202a and 202b. One or more transceivers 206a and 206b may convert user data, control information, radio signals / channels processed using one or more processors 202a and 202b from baseband signals to RF band signals. To this end, one or more transceivers 206a and 206b may include (analog) oscillators and / or filters.

[0085] Figure 3 is a diagram showing a method for processing a transmission signal applicable to the present disclosure. For example, the transmitted signal may be processed by a signal processing circuit. At this time, the signal processing circuit 1200 may include a scrambler 300, a modulator 320, a layer mapper 330, a precoder 340, a resource mapper 350, and a signal generator 360. At this time, for example, Figure 3 The operations / functions of Figure 2 may be performed by the processors 202a and 202b and / or transceivers 206a and 206b of Figure 3The hardware components can be implemented in Figure 2 processors 202a and 202b and / or Figure 2 transceivers 206a and 206b. Additionally, for example, blocks 310 to 350 can be implemented in Figure 2 processors 202a and 202b, and block 360 can be implemented in Figure 2 transceivers 206a and 206b, without being limited to the above embodiments.

[0086] A codeword can be converted into a radio signal by Figure 3 the signal processing circuit 300. Here, a codeword is a coded bit sequence of an information block. The information block can include a transport block (e.g., a UL-SCH transport block or a DL-SCH transport block). The radio signal can be transmitted through Figure 6 various physical channels (e.g., PUSCH and PDSCH). Specifically, a codeword can be converted into a bit sequence scrambled by a scrambler 310. The scrambling sequence for scrambling is generated based on an initial value, and the initial value can include ID information of the wireless device, etc. The scrambled bit sequence can be modulated by a modulator 320 into a modulated symbol sequence. The modulation method can include pi / 2-binary phase shift keying (pi / 2-BPSK), m-phase shift keying (m-PSK), m-quadrature amplitude modulation (m-QAM), etc.

[0087] The complex modulated symbol sequence can be mapped by a layer mapper 330 to one or more transmission layers. The modulated symbols of each transmission layer can be mapped by a precoder 340 to corresponding antenna ports (precoding). The output z of the precoder 340 can be obtained by multiplying the output y of the layer mapper 330 by an N*M precoding matrix W. Here, N can be the number of antenna ports, and M can be the number of transmission layers. Here, the precoder 340 can perform precoding after transform precoding (e.g., discrete Fourier transform (DFT)) for the complex modulated symbols. Additionally, the precoder 340 can perform precoding without performing transform precoding.

[0088] A resource mapper 350 can map the modulated symbols of each antenna port to time-frequency resources. The time-frequency resources can include multiple symbols in the time domain (e.g., CP-OFDMA symbols and DFT-s-OFDMA symbols), and include multiple subcarriers in the frequency domain. A signal generator 360 can generate a radio signal from the mapped modulated symbols and can transmit the generated radio signal to another device through each antenna. For this purpose, the signal generator 360 can include an inverse fast Fourier transform (IFFT) module, a cyclic prefix (CP) inserter, a digital-to-analog converter (DAC), a frequency upconverter, etc.

[0089] The signal processing process for a received signal in a wireless device can be configured as Figure 3 the reverse process of signal processing processes 310 to 360. For example, a wireless device (e.g., Figure 2 200a or 200b) can receive a radio signal from the outside through an antenna port / transceiver. The received wireless signal can be converted into a baseband signal by a signal restorer. For this purpose, the signal restorer can include a frequency downlink converter, an analog-to-digital converter (ADC), a CP remover, and a fast Fourier transform (FFT) module. Thereafter, the baseband signal can be restored to a codeword through a resource demapping process, a post-coding process, a demodulation process, and a descrambling process. The codeword can be restored to the original information block through decoding. Therefore, the signal processing circuit (not shown) for the received signal can include a signal restorer, a resource demapper, a post-encoder, a demodulator, a descrambler, and a decoder.

[0090] Structure of the wireless device applicable to the present disclosure

[0091] Figure 4 is a diagram showing another example of a wireless device applicable to the present disclosure.

[0092] Referring to Figure 4 , the wireless device 400 can correspond to Figure 2 the wireless devices 200a and 200b, and includes various elements, components, units / parts, and / or modules. For example, the wireless device 400 can include a communication unit 410, a control unit (controller) 420, a memory unit (memory) 430, and additional components 440. The communication unit can include a communication circuit 412 and a transceiver 414. For example, the communication circuit 412 can include Figure 2 one or more processors 202a and 202b and / or one or more memories 204a and 204b of Figure 2 . For example, the transceiver 414 can include

[0093] The additional component 440 may be configured differently according to the type of the wireless device. For example, the additional component 440 may include at least one of a power unit / battery, an input / output unit, a driving unit, or a computing unit. Without being limited thereto, the wireless device 400 may be in the form of a robot ( Figure 1 , 100a), a vehicle ( Figure 1 , 100b-1 and 100b-2), an XR device ( Figure 1 , 100c), a handheld device ( Figure 1 , 100d), a home appliance ( Figure 1 , 100e), an IoT device ( Figure 1 , 100f), a digital broadcast terminal, a holographic device, a public safety device, an MTC device, a medical device, a fintech device (financial device), a security device, a climate / environment device, an AI server / device ( Figure 1 , 140), a base station ( Figure 1 , 120), a network node, etc. According to the usage example / service, the wireless device may be movable or may be used at a fixed position.

[0094] In Figure 4 , various elements, components, units / parts, and / or modules in the wireless device 400 may be connected to each other through a wired interface or at least some of them may be wirelessly connected through the communication unit 410. For example, in the wireless device 400, the control unit 420 and the communication unit 410 may be connected by a wired connection, and the control unit 420 and the first unit (e.g., 130 or 140) may be wirelessly connected through the communication unit 410. Additionally, each element, component, unit / part, and / or module of the wireless device 400 may further include one or more elements. For example, the control unit 420 may be composed of a group of one or more processors. For example, the control unit 420 may be composed of a group of communication control processors, application processors, electronic control units (ECUs), graphics processing processors, memory control processors, etc. In another example, the memory unit 430 may be composed of a random access memory (RAM), a dynamic RAM (DRAM), a read-only memory (ROM), a flash memory, a volatile memory, a non-volatile memory, and / or a combination thereof.

[0095] Handheld device applicable to the present disclosure

[0096] Figure 5 is a diagram showing an example of a handheld device applicable to the present disclosure.

[0097] Figure 5A handheld device applicable to the present disclosure is shown. The handheld device may include a smart phone, a smart tablet, a wearable device (e.g., a smart watch or smart glasses), and a handheld computer (e.g., a laptop computer, etc.). The handheld device may be referred to as a mobile station (MS), a user terminal (UT), a mobile subscriber station (MSS), a subscriber station (SS), an advanced mobile station (AMS), or a wireless terminal (WT).

[0098] Referring Figure 5 , the handheld device 500 may include an antenna unit (antenna) 508, a communication unit (transceiver) 510, a control unit (controller) 520, a memory unit (memory) 530, a power supply unit (power supply) 540a, an interface unit (interface) 540b, and an input / output unit 540c. The antenna unit (antenna) 508 may be part of the communication unit 510. Block 510 to block 530 / 540a to block 540c may respectively correspond to Figure 4 blocks 410 to 430 / 440 of

[0099] The communication unit 510 may transmit signals (e.g., data, control signals, etc.) to other wireless devices or base stations and receive signals (e.g., data, control signals, etc.) from other wireless devices or base stations. The control unit 520 may control the components of the handheld device 500 to perform various operations. The control unit 520 may include an application processor (AP). The memory unit 530 may store data / parameters / programs / codes / instructions required to drive the handheld device 500. Additionally, the memory unit 430 may store input / output data / information, etc. The power supply unit 540a may supply power to the handheld device 500 and include a wired / wireless charging circuit, a battery, etc. The interface unit 540b may support the connection between the handheld device 500 and another external device. The interface unit 540b may include various ports for connecting to external devices (e.g., audio input / output ports and video input / output ports). The input / output unit 440c may receive or output video information / signals, audio information / signals, data, and / or user input information. The input / output unit 540c may include a camera, a microphone, a user input unit, a display 540d, a speaker, and / or a haptic module.

[0100] For example, in the case of data communication, the input / output unit 540c may obtain user input information / signals (e.g., touch, text, voice, image, or video) from a user and store the user input information / signals in the memory unit 530. The communication unit 510 may convert the information / signals stored in the memory into a radio signal and directly transmit the converted radio signal to another wireless device or transmit the converted radio signal to a base station. Additionally, the communication unit 510 may receive a radio signal from another wireless device or a base station and then restore the received radio signal to the original information / signals. The restored information / signals may be stored in the memory unit 530 and then output through the input / output unit 540c in various forms (e.g., text, voice, image, video, and tactile).

[0101] Physical channels and general signal transmission

[0102] In a radio access system, a UE receives information from a base station on the DL and transmits information to the base station on the UL. The information transmitted and received between the UE and the base station includes general data information and various control information. Depending on the type / usage of the information transmitted and received between the base station and the UE, there are many physical channels.

[0103] Figure 6 is a diagram showing physical channels applicable to the present disclosure and a signal transmission method using the physical channels.

[0104] In step S611, a UE that is turned on again in a turned-off state or newly enters a cell performs an initial cell search operation, such as acquiring synchronization with a base station. Specifically, the UE synchronizes with the base station by receiving a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from the base station and obtains information such as a cell identifier (ID).

[0105] Thereafter, the UE may receive a physical broadcast channel (PBCH) signal from the base station and obtain in-cell broadcast information. Additionally, the UE may receive a downlink reference signal (DL RS) in the initial cell search step and check the downlink channel state. A UE that has completed the initial cell search may receive a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to the physical downlink control channel information in step S612, thereby obtaining more detailed system information.

[0106] After that, the UE can perform a random access procedure such as steps S613 to S616 to complete access to the base station. To this end, the UE can send a preamble (S613) through the Physical Random Access Channel (PRACH), and receive a Random Access Response (RAR) for the preamble through the Physical Downlink Control Channel and the corresponding Physical Downlink Shared Channel (S614). The UE can use the scheduling information in the RAR to send a Physical Uplink Shared Channel (PUSCH) (S615), and perform a contention resolution process, such as receiving a Physical Downlink Control Channel signal and the corresponding Physical Downlink Shared Channel signal (S616).

[0107] The UE that has performed the above process can perform the reception of a Physical Downlink Control Channel signal and / or a Physical Downlink Shared Channel signal (S617) and the transmission of a Physical Uplink Shared Channel (PUSCH) signal and / or a Physical Uplink Control Channel (PUCCH) signal (S618) as a general uplink / downlink signal transmission process.

[0108] The control information sent from the UE to the base station is collectively referred to as Uplink Control Information (UCI). UCI includes Hybrid Automatic Repeat Request Acknowledgment / Negative ACK (HARQ-ACK / NACK), Scheduling Request (SR), Channel Quality Indicator (CQI), Precoding Matrix Indicator (PMI), Rank Indicator (RI), Beam Indicator (BI) information, etc. At this time, UCI is usually sent periodically through the PUCCH, but in some embodiments, it can be sent through the PUSCH (for example, when sending control information and service data simultaneously). In addition, the UE can send UCI aperiodically through the PUSCH according to the request / indication of the network.

[0109] Figure 7 It is a diagram showing the structure of a radio frame applicable to the present disclosure.

[0110] The UL transmission and DL transmission based on the NR system can be based on Figure 7The frame shown. At this time, a radio frame has a length of 10 ms and can be defined as two 5-ms half-frames (HFs). A half-frame can be defined as five 1-ms sub-frames (SFs). A sub-frame can be divided into one or more time slots, and the number of time slots in a sub-frame can depend on the subcarrier spacing (SCS). At this time, according to the cyclic prefix (CP), each time slot can include 12 or 14 OFDM(A) symbols. If normal CP is used, each time slot can include 14 symbols. If extended CP is used, each time slot can include 12 symbols. Here, the symbols can include OFDM symbols (or CP-OFDM symbols) and SC-FDMA symbols (or DFT-s-OFDM symbols).

[0111] Table 1 shows the number of symbols per time slot, the number of time slots per frame, and the number of time slots per sub-frame according to the SCS when normal CP is used, and Table 2 shows the number of symbols per time slot, the number of time slots per frame, and the number of time slots per sub-frame according to the SCS when extended CP is used.

[0112] [Table 1]

[0113]

[0114] [Table 2]

[0115]

[0116] In Tables 1 and 2 above, N slot symb can indicate the number of symbols in a time slot, N frame,μ slot can indicate the number of time slots in a frame, and N subframe，μ slot can indicate the number of time slots in a sub-frame.

[0117] In addition, in the system to which the present disclosure is applicable, OFDM(A) parameter sets (e.g., SCS, CP length, etc.) can be set differently among a plurality of cells merged into one UE. Therefore, the (absolute time) period of a time resource (e.g., SF, time slot, or TTI) composed of the same number of symbols (collectively referred to as a time unit (TU) for convenience) can be set differently among the merged cells.

[0118] NR can support multiple parameter sets (or subcarrier spacings (SCSs)) for supporting various 5G services. For example, when the SCS is 15 kHz, it supports wide areas in traditional cellular bands, when the SCS is 30 kHz / 60 kHz, it supports dense cities, lower latency, and wider carrier bandwidths, and when the SCS is 60 kHz or higher, it can support bandwidths greater than 24.25 GHz to overcome phase noise.

[0119] The NR frequency band is defined as two types of frequency ranges (FR1 and FR2). FR1 and FR2 can be configured as shown in the following table. Additionally, FR2 can refer to millimeter wave (mmW).

[0120] [Table 3]

[0121] Frequency range specification Corresponding frequency range Subcarrier spacing FR1 410 MHz - 7125 MHz 15, 30, 60 kHz FR2 24250 MHz - 52600 MHz 60, 120, 240 kHz

[0122] Furthermore, for example, in the communication system to which the present disclosure is applicable, the above parameter sets can be set differently. For example, the terahertz wave (THz) frequency band can be used as a frequency band higher than FR2. In the THz frequency band, the SCS can be set to be greater than the SCS of the NR system, and the number of time slots can be set differently, without being limited to the above embodiments. The THz frequency band will be described below.

[0123] Figure 8 is a diagram showing the time slot structure applicable to the present disclosure.

[0124] One time slot includes multiple symbols in the time domain. For example, in the case of normal CP, one time slot includes seven symbols, and in the case of extended CP, one time slot includes six symbols. A carrier includes multiple subcarriers in the frequency domain. A resource block (RB) can be defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain.

[0125] Additionally, a bandwidth part (BWP) is defined as multiple consecutive (P) RBs in the frequency domain and can correspond to one parameter set (e.g., SCS, CP length, etc.).

[0126] A carrier can include at most N (e.g., five) BWPs. Data communication is performed through the activated BWP, and only one BWP can be activated for one UE. In the resource grid, each element is called a resource element (RE), and one complex symbol can be mapped.

[0127] 6G communication value system

[0128] The 6G (wireless communication) system has purposes such as the following: (i) very high data rate per device, (ii) very large number of connected devices, (iii) global connectivity, (iv) very low latency, (v) reduced energy consumption of battery - less IoT devices, ( v i) ultra - reliable connectivity, and (vii) connected intelligence with machine - learning capabilities. The vision of the 6G system can include four aspects, such as "intelligent connectivity", "deep connectivity", "holographic connectivity", and "ubiquitous connectivity", and the 6G system can meet the requirements shown in Table 4 below. That is, Table 4 shows the requirements of the 6G system.

[0129] [Table 4]

[0130] Peak data rate per device 1 Tbps E2E latency 1 ms Maximum spectral efficiency 100 bps / Hz Mobility support Up to 1000 km / hr Satellite integration Fully AI Fully Autonomous vehicle Fully XR Fully Tactile communication Fully

[0131] At this time, the 6G system can have key factors such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), massive machine-type communication (mMTC), AI-integrated communication, tactile Internet, high throughput, high network capacity, high energy efficiency, low backhaul and access network congestion, and enhanced data security.

[0132] Figure 9 is a diagram showing an example of a communication structure that can be provided in a 6G system applicable to the present disclosure.

[0133] Reference Figure 9 , the 6G system will have 50 times higher simultaneous wireless communication connectivity than the 5G wireless communication system. URLLC, which is a key feature of 5G, will become an even more important technology by providing an end-to-end latency of less than 1 ms in 6G communication. At this time, different from the frequently used domain spectral efficiency, the 6G system can have much better volumetric spectrum efficiency. The 6G system can provide advanced battery technology for energy harvesting and very long battery life, so in the 6G system, mobile devices may not need to be charged separately. In addition, in 6G, new network characteristics can be as follows.

[0134] - Satellite-integrated network: To provide a global mobile group, 6G will be integrated with satellites. Integrating terrestrial waveforms, satellites, and public networks into a single wireless communication system may be very important for 6G.

[0135] - Connected intelligence: Different from previous generations of wireless communication systems, 6G is innovative and the wireless evolution can be updated from "connected things" to "connected intelligence". AI can be applied at each step of the communication process (or each signal processing process described below).

[0136] - Seamless integration of wireless information and energy transfer: The 6G wireless network can transfer electricity to charge the batteries of devices such as smartphones and sensors. Therefore, wireless information and energy transfer (WIET) will be integrated.

[0137] - Ubiquitous ultra-3D connectivity: Access to the network and core network functions of drones and very low Earth orbit satellites will establish ultra-3D connectivity ubiquitously in 6G.

[0138] Among the new network characteristics of 6G, several general requirements can be as follows.

[0139] - Small cell network: As a result of the improvement in throughput, energy efficiency, and spectral efficiency in cellular systems, the idea of a small cell network has been introduced to improve the received signal quality. Therefore, a small cell network is an essential feature of 5G and beyond 5G (5GB) communication systems. Thus, the 6G communication system also adopts the characteristics of a small cell network.

[0140] - Ultra-dense heterogeneous network: The ultra-dense heterogeneous network will be another important feature of the 6G communication system. A multi-layer network composed of heterogeneous networks improves the overall QoS and reduces costs.

[0141] - High-capacity backhaul: The backhaul connection is characterized by a high-capacity backhaul network to support high-capacity services. High-speed optical fibers and free space optical (FSO) systems may be possible solutions to this problem.

[0142] - Radar technology integrated with mobile technology: High-precision positioning (or location-based services) through communication is one of the functions of the 6G wireless communication system. Therefore, radar systems will be integrated with the 6G network.

[0143] - Softwareization and virtualization: Softwareization and virtualization are two important functions that are the basis of the design process in 5GB networks to ensure flexibility, reconfigurability, and programmability.

[0144] Quantum communication

[0145] Quantum communication is a next-generation communication technology that can overcome the limitations of existing information and communication (such as security and high-speed computing) by applying quantum mechanical properties to the field of information and communication. Quantum communication provides a means to generate, transmit, process, and store information in the superposition of 0 and 1, which is impossible or difficult to express according to the binary bit information used in existing communication technologies. In existing communication technologies, information is transmitted between the sender and the receiver using wavelength or amplitude, while in quantum communication, photons, which are the smallest units of light, are used to transmit information between the sender and the receiver. In particular, in quantum communication, quantum uncertainty, quantum irreversibility, and non-clonability can be used for the polarization of photons (light) or the phase difference between them, so quantum communication allows for communication with perfect security. In addition, quantum communication can allow for high-speed communication by using quantum entanglement under specific conditions.

[0146] The present disclosure proposes a method and apparatus for user authentication, which is a process of checking whether an entity that exchanges information via a quantum channel is a pre-authorized object in quantum key distribution. More specifically, a user authentication method is proposed, which uses a symmetric key pre-shared between the sender and the receiver for basis selection (i) when generating quantum information for user authentication and (ii) when measuring quantum information for user authentication.

[0147] In the following, general matters of user authentication will be first described to help understand the method proposed by the present disclosure.

[0148] General QKD (Quantum Key Distribution)

[0149] The QKD technology is a technology for securely sharing secret symmetric key information required for encrypting and decrypting message information to be transmitted via a classical channel between a sender and a receiver. Figure 10 is a diagram showing an example of a quantum coding communication system to which QKD is applied. Refer to Figure 10 , in QKD, the sender 1010 first shares secret key information with the receiver 1020 via a quantum channel, and generates a final secret symmetric key through a post-processing process including sifting, QBER estimation, error correction, and privacy amplification using a classical channel (= public channel). After that, the generated secret key is combined with the message information that the sender intends to transmit, thereby encrypting the transmission information, and then the encrypted transmission information is transmitted using an existing communication channel, and the receiver decrypts the received encrypted information using the same secret key as that used by the sender, thereby restoring the message information sent by the sender.

[0150] Man-in-the-middle attack and user authentication

[0151] In the QKD protocol, the absolute security of the secret key transmitted via the quantum channel can be guaranteed by the no-cloning theorem, which is a quantum mechanical property. More specifically, by using a QBER (quantum bit error rate) estimation process for a part of the information transmitted via the quantum channel, it is possible to check whether the message information transmitted via the quantum channel has been eavesdropped on by a third party, thereby ensuring the security of the transmitted message. However, as shown in Figure 11As shown, if a third party Eve 1130 exists between Alice 1110 as the sender and Bob 1120 as the receiver and attempts a man-in-the-middle attack by pretending to be the receiver to Alice 1110 and the sender to Bob 1120, it is impossible to check whether the third party Eve 1130 performs a man-in-the-middle attack only based on the results of QBER estimation of the information transmission between Alice 1110 and Eve 1130 and the results of QBER estimation of the information transmission between Eve 1130 and Bob 1120. That is, the third party Eve 1130 can receive the information sent by Alice 1110 via the quantum channel and at the same time send the information tampered with by Eve 1130 to Bob 1120. Therefore, it is impossible to identify the existence of an eavesdropper only through the QBER estimation process of the corresponding check sequences sent between Alice 1110 and Eve 1130 and between Eve 1130 and Bob 1120. Through a man-in-the-middle attack, the third party Eve 1130 can know all the content of the delivered data, relay the data between Alice 1110 and Bob 1120 at the same time, and can also attempt to impersonate / fabricate data. Therefore, in order to prevent a man-in-the-middle attack, a user authentication process is required to confirm whether the sender and the receiver, who are the entities exchanging information, are authorized users.

[0152] Existing authentication techniques can be classified into hash function-based authentication schemes (which include elements of strong passwords) and information-theoretic security-based authentication schemes. In hash function-based authentication schemes, the collision probability of the hash function is used as a computation complexity-based authentication technique, and a representative hash function-based technique is the SHA technique. However, since hash function-based authentication schemes are based on computation complexity, it is very likely that they will face security threats in the future due to the emergence of quantum computers. Additionally, in a quantum cryptographic communication system, to enhance security, an authentication technique using a keyed hash function family, which is a combination of a symmetric key and a hash function based on information-theoretic security, is applied and used, and a quantum communication standardization organization such as ETSI (European Telecommunications Standards Institute) adopts a scheme using a keyed hash function family as a standard authentication scheme. In the above method, a hash function called strongly universal hash is used as a message authentication code (MAC) algorithm to generate the message authentication code (MAC) used in the authentication process, and a symmetric key used as a one-time password (OTP) is additionally used in the generation process. This scheme is known to be the most secure scheme because the possibility of recovering information from the MAC through a reverse process is very low unless the symmetric key information is known.

[0153] The MAC-based authentication technology is currently applied as a standard authentication method for quantum information transmission technologies such as QKD, and Figure 12 is a diagram showing an example of the MAC-based authentication technology.

[0154] The MAC is used to verify the integrity of a message and is an authentication technology based on the fact that it is difficult for a third party to know which MAC algorithm is used in MAC generation because the third party does not know the one-time symmetric key information previously shared between the sender 1210 and the receiver 1220. First, before performing the authentication process, the sender 1210 and the receiver 1220 share the same symmetric key information 1200 and MAC algorithms 1201 and 1202. After that, once the sender 1210 inputs the plaintext message for authentication into the MAC algorithm 1201, the algorithm to be used is selected from the MAC algorithm based on the value of the pre-shared key 1200. Next, when the plaintext message 1203 is input into the MAC algorithm 1201 selected by the sender 1210, the MAC 1205 is obtained as the output, and the sender 1210 sends the plaintext message 1203 and the MAC 1205 generated by itself via the classical channel so that the receiver 1220 can generate a MAC. The receiver inputs the received plaintext message 1204 into the MAC algorithm 1202 of the receiver 1220. At this time, the receiver 1220 can generate a MAC using the same MAC algorithm 1202 as the sender 1210 because it has the same pre-shared key as the sender 1210. Finally, the receiver 1220 compares the MAC 1205 sent by the sender 1210 and the MAC generated by the receiver 1220 to check if they match. If the value of the MAC 1205 sent by the sender 1210 matches the value of the MAC generated by the receiver 1220, the authentication passes / succeeds, and if the two values do not match, the authentication fails.

[0155] In the authentication scheme using the MAC, the pre-shared symmetric key information is not the information sent via the classical channel but the information previously agreed upon only by the sender and the receiver. Therefore, even if a third party who does not know the pre-shared symmetric key information obtains the message information, the third party cannot find out which MAC algorithm is applied from the message information obtained by the third party unless the third party obtains the symmetric key, so the security can be guaranteed. Therefore, it can be understood that the more the method of configuring the MAC algorithm changes, the higher the security of the authentication scheme using the MAC.

[0156] In the quantum key distribution (QKD) protocol, which is a security technology currently applied to 4G LTE / 5G, the Wegman-Carter Authentication (WCA) technology proposed by Wegman and Carter is adopted and used as the standard authentication technology, and a symmetric key generated in the form of a one-time password and a strong universal hash class is used to generate a tag as the MAC for authentication. Figure 13 FIG. is a diagram showing an example of an authentication scheme based on Wegman & Carter Authentication (WCA).

[0157] Figure 13 The authentication method is applicable to user authentication for checking changes in the sender / receiver during message transmission and message authentication for checking changes in the content and order of message information. In Figure 13 , the sender 1310 generates tag information 1305 used as the MAC from the message information 1303 by using the pre-shared key 1300 and the MAC algorithm 1301, and uses a hash function of the strong universal hash class as the MAC algorithm. In this case, the pre-shared key information 1300 allows selection of which hash function h k is to be used at H 1301 of the sender 1310 and H 1302 of the receiver 1320, and the pre-shared key is assigned log2|H| bits, where |H| represents the number of hash functions constituting the set of hash functions. The tag information 1305 is represented by T = h k (m), and is obtained by passing the message m of the authentication process as an input through the hash function h k selected from the pre-shared key. After that, the receiver 1320 compares the tag information 1306 of the receiver 1320 obtained from the pre-shared key 1300 and the hash function 1302 of the receiver 1320 with the tag information 1305 received from the sender 1310 by using the message 1303 received by the receiver 1320 to check the match between the two tag information, and then determines (1308) whether to perform authentication.

[0158] In the Wegman & Carter authentication technology, a hash function is used as the above MAC algorithm, and the hash function is a function that takes information of any length as an input and returns a hash value of a fixed length as an output. Since the original length text is reduced to a fixed size, the hash function is usually called a message digest.

[0159] Based on the following three characteristics, the hash function can be used as the MAC in the authentication process:

[0160] Preimage resistance (One-wayness): Given any output value y, it is computationally infeasible to find an input value x that satisfies y = h(x).

[0161] Second preimage resistance: Given any input value x, there exists h(x), and it is computationally infeasible to find another input value x' such that x ≠ x' and h(x) = h(x').

[0162] Collision resistance: It is computationally infeasible to find two input values x and x' such that the hash function h(x) = h(x').

[0163] Figure 14 is a diagram for describing the correlation between the number of hash functions and the collision probability.

[0164] In WCA, when Eve (a third party) attempts a man-in-the-middle attack, where the message m is replaced by m' and the tag is deduced and sent, Eve does not know which hash function the sender and receiver are using, so the tag is deduced by choosing any hash function, which makes the probability of success 1 / |T|, where |T| is the number of tags. That is to say, the number of tags is determined by the number |H| of the types of hash functions used, so it can be said that using more types of hash functions reduces the probability that Eve will deduce the tag. Therefore, it can be inferred that the larger the number of hash functions, the lower the collision probability, as in Figure 14 the collision probability formula in.

[0165] Definition of terms

[0166] For ease of explanation, the following symbols / abbreviations / terms may be used interchangeably in this disclosure.

[0167] -QDC: Quantum direct communication

[0168] -QSDC: Quantum secure direct communication

[0169] -QBER: Quantum bit error rate

[0170] -QKD: Quantum key distribution

[0171] -MIMA: Man-in-the-middle attack

[0172] -MAC: Message authentication code

[0173] -WCA: Wegman-Carter authentication

[0174] -OTP: One-time password

[0175] -ITS: Information-theoretic security

[0176] Through the user authentication method proposed in this disclosure, the following problems to be solved can be addressed:

[0177] (1)In existing quantum communication, when the sender Alice performs polarization encoding on message information and the receiver Bob measures the quantum information sent over the quantum channel, the sender and the receiver randomly select bases. Therefore, an additional information sharing process needs to be performed between the sender and the receiver to achieve a match between (i) the basis used by the sender Alice for polarization encoding and (ii) the basis used by the receiver Bob for measurement. In this process, there will be a 50% probability of basis mismatch, so half of the quantum information generated by the sender Alice for authentication and sent to the receiver Bob will be discarded.

[0178] More specifically, the foregoing problem will be described with reference to Figure 15 the following. Figure 15 FIG. is a diagram showing an example of quantum information transmission and reception based on random basis selection in an existing quantum communication method. In Figure 15 FIG., the sender 1501 encodes the information that the sender 1501 intends to send by using a quantum state determined based on a randomly selected basis, and then sends the encoded quantum information to the receiver 1502 (1510). After that, the receiver 1502 receives the quantum information sent by the sender 1501. In this case, the receiver 1502 does not know the basis used by the sender 1501 for encoding, so it randomly selects a basis to measure the received quantum information. Although in Figure 15 FIG., the sender 1501 uses the “+××+” basis to encode from left to right, the receiver 1502 measures the quantum information using the “××++” basis from left to right according to random basis selection because it does not know the information about the basis used by the sender 1501. Therefore, among the bases respectively used by the sender and the receiver, the first basis from the left and the third basis from the left have a basis mismatch. The bits with a basis mismatch between the sender and the receiver cannot be used as transmission information. Therefore, in quantum communication, after measuring the sent quantum state by using a random basis, a screening process is performed via a classical channel to select the bits with a matching basis between the sender and the receiver (S1530). As a result of the screening process, the sender and the receiver exchange the basis information used by the sender and the receiver via the classical channel, and the quantum information corresponding to the bits that match the basis used by the sender 1501 for encoding and the basis used by the receiver 1502 for measurement is used as valid information, and the remaining bits with a basis mismatch are discarded. In Figure 15 FIG., due to the basis mismatch, the information at the first position from the left and the information at the third position from the left of the quantum information sent by the sender 1501 do not match the information at the first position from the left and the information at the third position from the left of the quantum information measured by the receiver 1502, so half of the information sent by the sender 1501 is discarded. Although Figure 15An example is shown where only half of the bases used by the sending end and the receiving end match. However, when N (non-negative integer) bases are used for encoding at the sending end and measurement at the receiving end, at least one base can match, all bases can match, or all bases can mismatch. For a general illustration, the probability that at least one information unit in the information of length N will be discarded can be expressed as 1 - (1 / 2) N . That is, the probability that at least one information unit will be discarded refers to the value obtained by subtracting the probability value (1 / 2) that all bases will match at the sending end and the receiving end from the probability value 1 for all cases N .

[0179] Therefore, the present disclosure proposes a method for solving the following problem: the possibility of discarding half of the entire quantum information that may occur due to a 50% mismatch probability between the bases used by the sending end to encode the information generated for authentication and the bases used by the receiving end to measure the encoded and transmitted quantum information.

[0180] (2) Existing authentication methods for quantum communication using a classical channel need to assume that the users connected via the classical channel and the quantum channel are always the same.

[0181] More specifically, in quantum communication, a secret key or a message is sent via a quantum channel, and the classical channel is used as a channel for exchanging additional information required in additional processes such as post-processing. Therefore, when performing authentication with an existing authentication method, information for authentication is exchanged between the sending end and the receiving end via the classical channel, although the most important thing is to perform user authentication in the quantum channel where the information is delivered. Such an existing authentication method may be effective under the assumption that the users connected via the classical channel and the quantum channel are always the same, but if in fact a third party only performs a man-in-the-middle attack on the quantum channel, this assumption does not hold, which may lead to problems. Therefore, the present disclosure proposes a method for user authentication via a quantum channel.

[0182] (3) In existing authentication methods, both the sending end and the receiving end generate authentication information (MAC, tag, etc.), the sending end / receiving end delivers the generated authentication information to the receiving end / sending end, and the receiving end / sending end determines whether the authentication is passed (successful) based on whether the authentication information received from the sending end / receiving end matches the authentication information generated by the receiving end / sending end. However, during the process of delivering the authentication information generated by the sending end / receiving end from the sending end / receiving end to the receiving end / sending end via the channel, an error in the authentication information may occur due to the influence of the channel. In this case, an error correction code needs to be applied to achieve the matching of the authentication information between the sending end and the receiving end.

[0183] More specifically, the premise of the existing authentication method based on comparing the authentication information separately generated by the sending end and the receiving end is the assumption that no channel error occurs. However, since channel errors occur in the actual communication environment, even if the sending end and the receiving end separately generate the same authentication information through the same processing process, due to the error that occurs when the authentication information passes through the channel, it is impossible to achieve an exact match between the authentication information of the sending end and the receiving end. Due to the mismatch of the authentication information between the sending end and the receiving end (which is caused by the error that occurs when the authentication information passes through the channel), a process is required to recover the erroneous authentication information into the original error-free information through an error correction process. The error correction process serves as a factor increasing the complexity of the entire authentication process, resulting in a decrease in throughput. Therefore, the present disclosure proposes an authentication method that does not include an error correction process.

[0184] The present disclosure proposes a user authentication method applicable to QKD technology. Even in quantum communication, information to be sent (such as secret keys, messages, etc.) is delivered via a quantum channel. However, it is assumed that in the existing authentication scheme, authentication is performed via a classical channel, and the users connected via the quantum channel are always the same as those connected via the classical channel. However, this assumption may become a security weakness because quantum communication is used as a technology to ensure unconditional security. Therefore, the present disclosure proposes a user authentication method that uses the information sent through the quantum channel to compensate for the weakness caused by the assumption in the existing authentication method. In addition, the present disclosure proposes a method for exchanging authentication information without information loss caused by an additional process of exchanging basis information and random basis selection through an authentication method based on a pre-shared key. Finally, the present disclosure proposes an authentication method that determines whether authentication is passed based on the error rate of the authentication information. Compared with the existing authentication method, this authentication method can improve efficiency in terms of resource usage.

[0185] User authentication method based on the selection of bases using a pre-shared key (pre-shared symmetric key)

[0186] The present disclosure proposes a user authentication method that verifies whether the sending object and the receiving object are authorized objects by using a pre-shared key pre-shared between the sending end and the receiving end. More specifically, the method proposed by the present disclosure uses the pre-shared key to achieve a match between (i) the basis used by the sending end to generate the authentication message sent via the quantum channel and (ii) the basis used by the receiving end to measure the authentication message sent via the quantum channel. According to the method proposed by the present disclosure, problems occurring in the existing authentication method can be solved, including the partial discarding of the received authentication message information without using it for user authentication, which is caused when the receiving end measures the received authentication message based on random basis selection. Hereinafter, the method proposed by the present disclosure will be described in more detail with reference to Figure 16 More specifically, the method proposed by the present disclosure will be described.

[0187] Figure 16 It is a diagram showing an example of a base matching user authentication technique using a pre-shared key for use by a sender and a receiver. Figure 16 It shows the process of generating an authentication code for user authentication under the assumption of a noiseless channel. First, the same pre-shared key for user authentication is pre-shared between the sender 1601 and the receiver 1602. In this case, the pre-shared key has the same length as the authentication message information for authentication. The sender 1601 determines the base (1611) for encoding (polarization encoding) the authentication message based on the pre-shared key value. That is, the base for encoding the authentication message is determined according to the value of the bit at a specific position in the bit string constituting the pre-shared key. Refer to Figure 16 , it can be agreed that if the value of the bit at a specific position in the bit string constituting the pre-shared key is 0, an orthogonal base is used when encoding the bit corresponding to the bit at that specific position in the authentication message, and if the value of the bit at the specific position is 1, a diagonal base is used when encoding the bit corresponding to the bit at that specific position in the authentication message. Conversely, it can be agreed that if the value of the bit at a specific position in the bit string constituting the pre-shared key is 1, an orthogonal base is used when encoding the bit corresponding to the bit at that specific position in the authentication message, and if the value of the bit at the specific position is 0, a diagonal base is used when encoding the bit corresponding to the bit at that specific position in the authentication message. Return reference Figure 16 , since the value of the pre-shared key in Figure 16 is 0110, based on the value of the pre-shared key, the base information for encoding (polarization encoding) to send the authentication message is determined as +××+, and the sender 1601 generates a quantum state (quantum information) (1613) corresponding to the value of the authentication message by using the determined base. In this case, it can be agreed between the sender and the receiver that if the authentication message is in a polarization state of 0 degrees or 45 degrees, the bit value is 0, and if the authentication message is in a polarization state of 90 degrees or 135 degrees, the bit value is 1. More specifically, in Figure 16In this case, since the determined basis for encoding is “+××+” and the authentication message is 0101, the bit 0 of the authentication message corresponding to the first basis + is encoded by the + basis into a quantum state with 0-degree polarization, the bit 1 of the authentication message corresponding to the second basis × is encoded by the × basis into a quantum state with 135-degree polarization, the bit 0 of the authentication message corresponding to the third basis × is encoded by the × basis into a quantum state with 45-degree polarization, and the bit 1 of the authentication message corresponding to the fourth basis + is encoded by the + basis into a quantum state with 90-degree polarization. The sending end 1601 sends the generated quantum state information to the receiving end 1602 via a quantum channel. The receiving end 1602 selects a measurement basis (1621) for measuring the received quantum state information by using the same pre-shared key as that of the sending end 1601. More specifically, since the value of the pre-shared key is 0110, the measurement basis information for measuring the received quantum state information is determined to be +××+. In this case, the quantum state with 0-degree polarization of the first quantum information corresponding to the first measurement basis + as the received quantum state information is measured by using the measurement basis +, the quantum state with 135-degree polarization of the second quantum information corresponding to the second measurement basis × as the received quantum state information is measured by using the measurement basis ×, the quantum state with 45-degree polarization of the third quantum information corresponding to the third measurement basis × as the received quantum state information is measured by using the measurement basis ×, and the quantum state with 90-degree polarization of the fourth quantum information corresponding to the fourth measurement basis + as the received quantum state information is measured by using the measurement basis + (1623). Thereby, the receiving end 1602 can obtain the authentication code 0101. In this way, the receiving end 1602 measures the received quantum state information, which is the quantum information sent by the sending end 1601, by using the same basis as that used by the sending end 1601 to encode the authentication message as the measurement basis, thereby overcoming the problem of information loss caused by the mismatch of the bases between the sending end and the receiving end in the existing authentication method due to the measurement based on random basis selection. Finally, the sending end 1601 receives the authentication code obtained by the receiving end 1602 through measurement via a classical channel, and compares the authentication code generated by the sending end 1601 with the authentication code received from the receiving end, thereby determining whether the authentication is passed (successful) based on whether the two authentication codes match.

[0188] Although it has been described under the assumption of a noiseless channel Figure 16 , there are channel errors in an actual quantum channel. Therefore, even if the sending end and the receiving end each generate and measure the authentication message with the same basis, the receiving end cannot obtain the same authentication code as that generated by the sending end. Hereinafter, the application of the method proposed by the present disclosure on a noisy channel will be described in more detail with reference to Figure 17

[0189] Figure 17 FIG. is another example of a base matching user authentication technique that shows the use of a pre-shared key for use by a sender and a receiver. Figure 17 FIG. shows a process of generating an authentication code for user authentication, which relates to a method of user authentication in a channel with noise.

[0190] First, the same pre-shared key for user authentication is pre-shared between the sender 1701 and the receiver 1702. In this case, the pre-shared key has the same length as the authentication message information for authentication. The sender 1701 determines a base (1711) for encoding (polarization encoding) the authentication message based on the pre-shared key value. That is, the base for encoding the authentication message is determined according to the value of the bit at a specific position in the bit string constituting the pre-shared key. Referring to Figure 17 , it can be agreed that if the value of the bit at a specific position in the bit string constituting the pre-shared key is 0, an orthogonal base is used when encoding the bit corresponding to the bit at the specific position in the authentication message, and if the value of the bit at the specific position is 1, a diagonal base is used when encoding the bit corresponding to the bit at the specific position in the authentication message. Conversely, it can be agreed that if the value of the bit at a specific position in the bit string constituting the pre-shared key is 1, an orthogonal base is used when encoding the bit corresponding to the bit at the specific position in the authentication message, and if the value of the bit at the specific position is 0, a diagonal base is used when encoding the bit corresponding to the bit at the specific position in the authentication message.

[0191] Returning to reference Figure 17 , since the value of the pre-shared key in Figure 17 is 0110, based on the value of the pre-shared key, the base information for encoding (polarization encoding) to send the authentication message is determined to be +××+, and the sender 1701 generates a quantum state (quantum information) (1713) corresponding to the value of the authentication message by using the determined base. In this case, it can be agreed between the sender and the receiver that if the authentication message is in a polarization state of 0 degrees or 45 degrees, the bit value is 0, and if the authentication message is in a polarization state of 90 degrees or 135 degrees, the bit value is 1. More specifically, in Figure 17In [the situation], since the determined basis for encoding is “+××+” and the authentication message is 0101, the bit 0 of the authentication message corresponding to the first basis + is encoded by the + basis into a quantum state with 0-degree polarization, the bit 1 of the authentication message corresponding to the second basis × is encoded by the × basis into a quantum state with 135-degree polarization, the bit 0 of the authentication message corresponding to the third basis × is encoded by the × basis into a quantum state with 45-degree polarization, and the bit 1 of the authentication message corresponding to the fourth basis + is encoded by the + basis into a quantum state with 90-degree polarization. The sending end 1701 sends the generated quantum state information to the receiving end 1702 via a quantum channel. In this case, since Figure 17 there is a channel error in [the situation], due to the channel error, the quantum state information with 135-degree polarization at the second position having the quantum state information sent by the sending end 1701 is converted into quantum state information with 45-degree polarization. The receiving end 1702 selects a measurement basis (1721) for measuring the received quantum state information by using the same pre-shared key as that of the sending end 1701. More specifically, since the value of the pre-shared key is 0110, the measurement basis information for measuring the received quantum state information is determined to be +××+. In this case, the quantum state with 0-degree polarization of the first quantum information corresponding to the first measurement basis + as the received quantum state information is measured by using the measurement basis +, the quantum state with 45-degree polarization of the second quantum information corresponding to the second measurement basis × caused by the error and as the received quantum state information is measured by using the measurement basis ×, the quantum state with 45-degree polarization of the third quantum information corresponding to the third measurement basis × as the received quantum state information is measured by using the measurement basis ×, and the quantum state with 90-degree polarization of the fourth quantum information corresponding to the fourth measurement basis + as the received quantum state information is measured by using the measurement basis + (1723). Thus, the receiving end 1702 can obtain the authentication code 0001. Even if the receiving end performs measurement by using the pre-agreed measurement basis, due to the channel error, the authentication code at the sending end and the authentication code at the receiving end do not match. In the existing authentication method, the matching between the authentication code at the sending end and the authentication code at the receiving end can be achieved by performing error correction on the error caused by channel noise; however, when applying an error correction code, an additional process is required to exchange additional information required for error correction via a classical channel and perform error correction based on the additional information, thereby increasing the complexity of the entire authentication process. According to the method proposed in the present disclosure, in an actual communication environment where the mismatch between the authentication codes separately generated at the sending end and the receiving end is inevitable, it is possible to determine whether authentication is successful / failed without using an error correction code. Return reference Figure 17, the receiving end 1702 sends the authentication code 0001 obtained by the receiving end 1702 to the sending end 1701 via a classical channel, and the sending end 1701 estimates the error rate by comparing the value of the authentication code received from the receiving end 1702 with the value of the authentication code generated by the sending end 1701 (S1701). Next, the sending end 1701 determines whether the error rate estimated in S1710 is higher than the QBER threshold (S1720). The passing (success) of the authentication is determined based on the determination result of S1720. If the error rate estimated in S1710 is lower than the QBER threshold, it is determined that the authentication has been successful (S1721), or if the error rate estimated in S1710 is equal to or higher than the QBER threshold, it is determined that the authentication has failed (S1723). Once it is determined that the authentication has failed, the rest of the secret key sharing process is suspended. Based on Figure 17 's description, when there is a mismatch between the authentication code generated by the sending end and the authentication code obtained by the receiving end due to channel errors, user authentication can be performed without including a separate error correction process in the user authentication process. Therefore, the complexity of the entire user authentication process can be reduced.

[0192] Figure 18 is a flowchart showing the overall process of the user authentication scheme for base selection using a pre-shared key proposed in the present disclosure.

[0193] First, the same pre-shared key for user authentication is pre-shared between the sending end 1801 and the receiving end 1802 (S18010). In this case, the pre-shared key has the same length as the authentication message information for authentication. Here, the pre-shared key is shared before the secret key is sent in the QKD system and refers to a symmetric key that can be used as a one-time pad (OTP). After being used once, the pre-shared key is discarded and replaced by a process of updating with a new pre-shared key.

[0194] Next, the sending end 1801 determines the base (18020) for encoding (polar encoding) the authentication message based on the pre-shared key value. That is, the base for encoding the authentication message is determined according to the value of the bit at a specific position in the bit string constituting the pre-shared key. Refer to Figure 17, it can be established that if the value of the bit at a specific position in the bit string constituting the pre-shared key is 0, an orthogonal basis is used when encoding the bit in the authentication message corresponding to the bit at that specific position, and if the value of the bit at the specific position is 1, a diagonal basis is used when encoding the bit in the authentication message corresponding to the bit at that specific position. Conversely, it can be established that if the value of the bit at a specific position in the bit string constituting the pre-shared key is 1, an orthogonal basis is used when encoding the bit in the authentication message corresponding to the bit at that specific position, and if the value of the bit at the specific position is 0, a diagonal basis is used when encoding the bit in the authentication message corresponding to the bit at that specific position.

[0195] Next, the sender 1801 generates classical message information for user authentication (authentication message information), and stores the classical message information for user authentication to compare it later with the authentication code obtained by the receiver from the sender (S18030).

[0196] After that, the sender 1801 generates quantum state authentication message information based on the basis determined by the pre-shared key and the classical message information for authentication (authentication message information) (S18040), and then sends the quantum state authentication message information to the receiver 1802 via a quantum channel (S18050).

[0197] The receiver 1802 receives the quantum state authentication message information from the sender 1801, selects a measurement basis for measuring the received quantum state authentication message information by using the same pre-shared key as that of the sender 1801, and performs the measurement (S18060). The receiver 1802 stores the measured quantum state authentication message information (S18070). Next, the receiver 1802 sends the measured quantum state authentication message information (measurement value) to the sender 1801 via a classical channel (S18080).

[0198] The sender 1801 receives the quantum state authentication message information (measurement value) measured by the receiver 1802, and calculates (estimates) the error rate by comparing the received quantum state authentication message information (measurement value) measured by the receiver 1802 and the classical message information for authentication (authentication message information) generated by the sender 1801 (S18090).

[0199] Next, the sender 1801 determines whether the error rate calculated (estimated) in S18090 is higher than the QBER threshold (S18110). Authentication pass (success) is determined based on the determination result in S18110. If the error rate estimated in S18110 is lower than the QBER threshold, it is determined that the authentication has been successful (S18111), or if the error rate estimated in S18110 is equal to or higher than the QBER threshold, it is determined that the authentication has failed (S18113). Once it is determined that the authentication has failed, the remainder of the secret key sharing process is suspended (S18115).

[0200] Configuration of a quantum coding communication system based on a user authentication method using a pre-shared key for base selection

[0201] Hereinafter, a method for configuring a quantum coding communication system using a user authentication method based on basis selection using a pre-shared key proposed in the present disclosure will be described.

[0202] Figure 19 is a diagram showing an example of a quantum coding communication system based on a user authentication method of basis selection using a pre-shared key.

[0203] The QKD sender generates message information 1900, which includes (i) authentication message information for user authentication, (ii) information for QBER check, and (iii) secret key information for ensuring the security of data transmitted through the classical channel (S1910). In this case, compared with the QBER estimation information included in the message information 1900 or the information used as the secret key, the position of the authentication message information in the message information 1900 can be pre-specified and shared between the sender and the receiver, as pre-agreed between the sender and the receiver. Therefore, the position of the authentication message information in the message information 1900 is determined based on the previously agreed position, and Figure 19 1900 in indicates that the front part of the transmission information is used as the authentication message information. In step S1910, a user authentication process is performed to check whether the QKD sender and the QKD receiver are pre-authorized users by using the received authentication message information. In the user authentication process of step S1910, the user authentication technology proposed in the present disclosure is applied, in which a basis is selected based on a pre-shared key. The pre-shared key used in the user authentication process needs to be Figure 19 pre-shared (initial user authentication) or updated (user authentication performed after the initial user authentication) before the start of the user authentication process in, and the process of pre-sharing or updating the pre-shared key can be performed before generating the secret key and the QBER check sequence using QKD technology, although Figure 19 illustrates that the process is performed in the first stage of the user authentication process.

[0204] If, as a result of the user authentication process in step S1910, the user authentication is successful, the sender and the receiver perform post-processing of a secret symmetric key for data encryption (S1920). Here, the post-processing process is performed through sieving, QBER estimation, error correction, and privacy amplification. Through the post-processing process, a secret symmetric key ensuring security is obtained (S1930).

[0205] However, since the user authentication process is required every time a secret key is sent through the quantum channel, the pre-shared key for the authentication process needs to be updated. To update the pre-shared key, some of the secret symmetric keys generated through the post-processing process are used as the pre-shared key for the next user authentication process. Other secret keys other than the secret keys for updating the pre-shared key are used for encryption / decryption of data sent through the classical channel.

[0206] Figure 20 is a flowchart showing an example of a QKD system including a user authentication process based on a pre-shared key and a pre-shared key update method.

[0207] S2010: Step S2010 represents a process of sending information for a secret key and for QBER estimation through the quantum channel and performing measurements. More specifically, the sender 2001 generates random numbers for the secret key and QBER check (S2011). After that, the sender 2001 encodes the generated random numbers for the secret key and QBER check and sends them to the receiver 2002 (S2013). Next, the receiver 2002 performs measurements by using an arbitrary basis for the received quantum state information (S2015).

[0208] S2020: Step S2020 represents the user authentication technique proposed in the present disclosure. First, the same pre-shared key for user authentication is pre-shared or updated between the sender 2001 and the receiver 2002 (S2021). In this case, the pre-shared key has the same length as the authentication message information for authentication. Here, the pre-shared key is shared before sending the secret key in the QKD system and refers to a symmetric key that can be used as a one-time password (OTP). After being used once, the pre-shared key is discarded and replaced through a process of updating with a new pre-shared key.

[0209] Next, the sender 2001 generates information for authentication (S2022). Next, the sender 2001 stores the generated information for authentication, determines a basis for encoding (polar encoding) the information for authentication based on a pre-shared key value, and encodes the information for authentication into a quantum state by using the determined basis and sends it to the receiver 2002. The sender stores the information for authentication, encodes the information into a quantum state, and sends the quantum state (S2023).

[0210] The receiver 2002 receives the quantum state authentication message information from the sender 2001, selects a measurement basis for measuring the received quantum state authentication message information by using the same pre-shared key as the sender 2001, performs the measurement, and stores the measured quantum state authentication message information (S2024).

[0211] Next, the receiver 2002 sends the measured quantum state authentication message information (measurement value) to the sender 2001 via a classical channel (S2025).

[0212] The sender 2001 receives the quantum state authentication message information (measurement value) measured by the receiver 2002, and calculates (estimates) the error rate by comparing the received quantum state authentication message information (measurement value) measured by the receiver 2002 and the classical message information for authentication (authentication message information) generated by the sender 2001 (S2026).

[0213] Next, the sender 2001 determines whether the authentication is passed based on the error rate calculated (estimated) in S2026 (S2027). More specifically, the sender 2001 determines whether the error rate calculated (estimated) in S2026 is higher than the QBER threshold. The passing (success) of the authentication is determined based on the determination result. If the estimated error rate is lower than the QBER threshold, it is determined that the authentication has been successful, or if the estimated error rate is equal to or higher than the QBER threshold, it is determined that the authentication has failed. Once it is determined that the authentication has failed, the rest of the secret key sharing process is suspended.

[0214] S2030: Once it is determined that the authentication has been successful, step S2030 is executed. Step 2030 represents the post-processing procedure required to share a secret symmetric key between the sender and the receiver. More specifically, the post-processing procedure is performed through sieving (S2031), QBER estimation (S2033), error correction (S2035), and privacy amplification (S2037). In this case, at step S2031, the measurement position and basis information are exchanged between the sender 2001 and the receiver 2002 (S2032). In addition, at step S2033, the QBER check information is exchanged between the sender 2001 and the receiver 2002 (S2034). Next, at step S2035, additional information for error correction is exchanged between the sender 2001 and the receiver 2002 (S2036). Through the post-processing procedure, a secret symmetric key that ensures security is obtained.

[0215] S2040: Step S2040 represents the process of updating the key used for authentication and generating a secret key. After the post-processing procedure is completed, at this step, the process of separating a part of the finally shared symmetric key and updating it as the pre-shared key for the next authentication process (S2041) and the process of using the remaining information left after the update from the pre-shared key as the secret key S2043 are executed.

[0216] Effect

[0217] The present disclosure proposes a user authentication method using a pre-shared symmetric key, which ensures security against man-in-the-middle attacks in the QKD protocol, and the following effects can be achieved according to the method proposed in the present disclosure:

[0218] First, compared with the basis selection scheme in the existing authentication method, the sender and the receiver can respectively select the bases for encoding / measurement based on the pre-shared key, thus solving the problem of partial removal of the authentication information generated by the sender during the process of basis selection at the receiver. More specifically, in the existing quantum coding communication method, the sender does not give the receiver basis information used at the sender before receiving information from the receiver to ensure security. Therefore, when the receiver measures the received information, it measures / receives the transmitted information through random basis selection. Therefore, for the information at a specific position, the probability that the basis used by the sender for encoding and the basis used by the receiver for measurement do not match is 50%. Therefore, the sender and the receiver exchange their basis information with each other via the classical channel and discard the information measured with non-matching bases. Therefore, using the existing basis selection scheme in the authentication process may lead to partial loss of authentication information. However, with the method proposed in the present disclosure, according to the idea of performing the authentication process based on the same pre-shared key previously shared and owned by the sender and the receiver, the pre-shared key can be used to achieve basis matching between the sender and the receiver, thus solving the problem of information loss caused by the mismatch of basis selection between the sender and the receiver.

[0219] Next, in the method proposed in the present disclosure, the sender and the receiver select the basis based on the pre-shared key and do not require screening performed via the classical channel to achieve basis matching between the sender and the receiver, thus reducing the complexity of the overall authentication process by omitting the screening process. More specifically, in the existing quantum coding communication method, the receiver randomly selects the basis for measuring the quantum information sent from the sender. The sender and the receiver exchange information about the bases they use with each other via the classical channel, and the sender and the receiver need to perform a screening process to identify the positions where the bases match, and then exchange the positions where the bases match. However, in the method proposed in the present disclosure, the sender and the receiver can select the same basis based on the value of the same pre-shared key previously shared between the sender and the receiver, which eliminates the need for the screening process, thus reducing the configuration complexity of the authentication process.

[0220] In addition, in the method proposed in the present disclosure, the passing of authentication is determined based on the error rate, so there is no need to perform an error correction process to achieve the matching between the authentication information separately generated by the sender and the receiver. More specifically, in the existing authentication method, the passing of authentication is determined based on whether the authentication information separately generated by the sender and the receiver matches each other. To determine the passing of authentication, a process of correcting the errors that occur during the transmission process on the quantum channel needs to be performed. However, in the method proposed in the present disclosure, the passing of authentication is determined based on whether the error rate that occurs during the process of passing through the channel is equal to or lower than the QBER threshold, which eliminates the need to use error correction codes, thus simplifying the authentication process.

[0221] Finally, the method proposed in the present disclosure achieves direct user authentication between objects connected via a quantum channel. More specifically, in the WCA method, which is conventionally used as a QKD user authentication technique, authentication is performed via a classical channel, and thus security can be ensured only on the premise that the objects connected via the quantum channel and the objects connected via the classical channel are always the same. However, the method proposed in the present disclosure can perform direct user authentication on the objects connected via the quantum channel because the authentication information is directly sent via the quantum channel, and user authentication is determined by using the information sent via the quantum channel.

[0222] Figure 21 is a flowchart showing an example of the user authentication method proposed in the present disclosure executed by a sender.

[0223] To perform user authentication in a quantum communication system, the sender generates authentication quantum information by encoding an authentication message for user authentication based on a pre-shared key (S2110).

[0224] Here, the basis for encoding each bit element constituting the authentication message is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key.

[0225] Next, the sender sends the authentication quantum information to the receiver via the quantum channel (S2120).

[0226] After that, the sender receives authentication quantum information measurement information related to the value obtained by the receiver measuring the authentication quantum information (S2130).

[0227] Next, the sender performs user authentication with the receiver based on the authentication quantum information measurement information (S2140).

[0228] In addition, the sender includes: a transmitter for sending wireless signals; a receiver for receiving wireless signals; at least one processor; and at least one computer memory, the at least one computer memory being operably connected to the at least one processor and storing instructions that, when executed by the at least one processor, perform operations. In this case, the operations include those described above in Figure 21 described steps.

[0229] In addition, Figure 21 the operations described in Figure 21 can be stored in a non-transitory computer-readable medium (CRM) storing one or more instructions. The non-transitory computer-readable medium stores one or more instructions executable by one or more processors, and the one or more instructions cause the sender to perform the operations described in

[0230] In addition, a device including one or more memories and one or more processors functionally connected to the one or more memories controls the one or more processors to execute Figure 21 the operations described in

[0231] Figure 22 is a flowchart showing an example of the user authentication method proposed by the present disclosure executed by the receiving end.

[0232] To perform user authentication in a quantum communication system, the receiving end receives authentication quantum information generated by encoding an authentication message for user authentication based on a pre-shared key from the sending end (S2210).

[0233] Here, the basis for encoding each bit element constituting the authentication message is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key.

[0234] After that, the receiving end receives the authentication quantum information from the sending end via a quantum channel (S2220).

[0235] Next, the receiving end measures the received authentication quantum information based on the pre-shared key (S2230).

[0236] In this case, the measurement basis for measuring each bit element constituting the received authentication quantum information is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key.

[0237] Next, the receiving end sends authentication quantum information measurement information related to the value obtained by measuring the authentication quantum information by the receiving end to the sending end (S2240).

[0238] After that, the receiving end performs user authentication with the sending end based on the authentication quantum information measurement information (S2250).

[0239] In addition, the receiving end includes: a transmitter for sending wireless signals; a receiver for receiving wireless signals; at least one processor; and at least one computer memory, the at least one computer memory being operably connected to the at least one processor and storing instructions that, when executed by the at least one processor, perform operations. In this case, the operations include those described above in Figure 22 .

[0240] In addition, Figure 22The operations described herein can be stored in a non-transitory computer-readable medium (CRM) that stores one or more instructions. The non-transitory computer-readable medium stores one or more instructions executable by one or more processors, and the one or more instructions cause a receiving end to perform Figure 22 the operations described herein.

[0241] In addition, an apparatus including one or more memories and one or more processors functionally connected to the one or more memories controls the one or more processors to perform Figure 22 the operations described herein.

[0242] The embodiments of the present disclosure described above are combinations of elements and features of the present disclosure. Unless otherwise specified, an element or feature can be considered optional. Each element or feature can be practiced without being combined with other elements or features. In addition, embodiments of the present disclosure can be constructed by combining a part of elements and / or features. The order of operations described in the embodiments of the present disclosure can be rearranged. Some configurations of any one embodiment can be included in another embodiment and can be replaced with corresponding configurations of another embodiment. It will be apparent to those skilled in the art that claims not explicitly recited in the appended claims can be presented as embodiments of the present disclosure in combination, or can be included as new claims by subsequent amendments after the filing of this application.

[0243] Embodiments of the present disclosure can be implemented by various means, such as, for example, hardware, firmware, software, or combinations thereof. In a hardware configuration, the method according to an embodiment of the present disclosure can be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

[0244] In a firmware or software configuration, embodiments of the present disclosure can be implemented in the form of modules, procedures, functions, etc. For example, software code can be stored in a memory unit and executed by a processor. The memory can be located inside or outside the processor and can send data to and receive data from the processor via various known means.

[0245] Those skilled in the art will understand that the present disclosure can be implemented in other specific ways than those described herein without departing from the spirit and basic features of the present disclosure. Therefore, the above-described embodiments are to be construed in all respects as illustrative and not restrictive. The scope of the present disclosure should be determined by the appended claims and their legal equivalents, rather than by the above description, and all changes within the meaning and scope of the appended claims are intended to be included therein.

[0246] Industrial applicability

[0247] Although the present disclosure has been mainly described with examples applied to 3GPP LTE / LTE-A and 5G systems, the present disclosure can also be applied to various wireless communication systems in addition to 3GPP LTE / LTE-A and 5G systems.

Claims

1. A method for user authentication at a sending end in a quantum communication system, the method comprising the following steps: Generating authentication quantum information by encoding an authentication message for user authentication based on a pre-shared key, wherein the basis for encoding each bit element constituting the authentication message is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key; Sending the authentication quantum information to a receiving end via a quantum channel; Receiving, from the receiving end, authentication quantum information measurement information related to a value obtained by measuring the authentication quantum information by means of the receiving end; and Performing user authentication with the receiving end based on the authentication quantum information measurement information.

2. The method according to claim 1, wherein The length of the pre-shared key is equal to the length of the authentication message for user authentication.

3. The method according to claim 1, wherein, The pre-shared key is used to determine the basis used by the receiving end to measure the authentication quantum information.

4. The method according to claim 1, wherein, The success of the user authentication is determined based on the error rate between (i) the value of the authentication message generated by the sending end and (ii) the value of the authentication quantum information measurement information obtained by the sending end.

5. The method according to claim 2, wherein, The success of the user authentication is determined based on the comparison result between (i) the error rate between the value of the authentication message generated by the sending end and the value of the authentication quantum information measurement information obtained by the sending end and (ii) a threshold for determining the success of user authentication.

6. The method according to claim 5, wherein Based on (i) the error rate between the value of the authentication message generated by the sending end and the value of the authentication quantum information measurement information obtained by the sending end being lower than (ii) the threshold for determining the success of the user authentication, the user authentication is successful.

7. The method according to claim 6, wherein, Based on (i) the error rate between the value of the authentication message generated by the sending end and the value of the authentication quantum information measurement information obtained by the sending end being equal to or higher than (ii) the threshold for determining the success of the user authentication, the user authentication fails.

8. The method according to claim 7, wherein The QBER threshold for QBER estimation for determining the presence of an eavesdropper on the quantum channel is used as the threshold for determining the success of the user authentication.

9. The method according to claim 6, wherein the method further comprises the following steps: Based on the success of the user authentication, sending a secret key for encrypting classical information transmitted via a classical channel to the receiving end.

10. The method according to claim 9, the method further comprising the following steps: Encrypting the classical information based on the secret key; and Sending the encrypted classical information to the receiving end via the classical channel.

11. A sending end for user authentication in a quantum communication system, the sending end comprising: A transmitter for sending wireless signals; A receiver for receiving wireless signals; At least one processor; And At least one computer memory operatively connectable to the at least one processor and storing instructions that, when executed by the at least one processor, perform operations, The operations comprising: Generate authentication quantum information by encoding an authentication message for user authentication based on a pre-shared key, wherein the basis for encoding each bit element constituting the authentication message is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key; Transmit the authentication quantum information to a receiving end via a quantum channel; Receive authentication quantum information measurement information related to a value obtained by measuring the authentication quantum information by the receiving end; and Perform user authentication with the receiving end based on the authentication quantum information measurement information.

12. A method for user authentication at a receiving end in a quantum communication system, the method comprising the following steps: Receive, from a sending end, authentication quantum information generated by encoding an authentication message for user authentication based on a pre-shared key, wherein the basis for encoding each bit element constituting the authentication message is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key; Receive the authentication quantum information from the sending end via a quantum channel; Measure the received authentication quantum information based on the pre-shared key, wherein the measurement basis for measuring each bit element constituting the received authentication quantum information is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key; Send authentication quantum information measurement information related to a value obtained by measuring the authentication quantum information by the receiving end to the sending end; and Perform user authentication with the sending end based on the authentication quantum information measurement information.

13. A receiving end for user authentication in a quantum communication system, the receiving end comprising: A transmitter for transmitting wireless signals; A receiver for receiving wireless signals; At least one processor; And At least one computer memory operatively connectable to the at least one processor and storing instructions that, when executed by the at least one processor, perform operations, The operations comprising: Receive, from a sending end, authentication quantum information generated by encoding an authentication message for user authentication based on a pre-shared key, wherein the basis for encoding each bit element constituting the authentication message is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key; Receive the authentication quantum information from the sending end via a quantum channel; Measure the received authentication quantum information based on the pre-shared key, Among them, the measurement basis for measuring each bit element constituting the received authentication quantum information is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key; Send authentication quantum information measurement information related to the value obtained by measuring the authentication quantum information by the receiving end to the sending end; and Perform user authentication with the sending end based on the authentication quantum information measurement information.

14. A non-transitory computer-readable medium CRM storing one or more instructions, the one or more instructions being executable by one or more processors and including: Generate authentication quantum information by encoding an authentication message for user authentication based on a pre-shared key, wherein the basis for encoding each bit element constituting the authentication message is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key; Send the authentication quantum information to a receiving end via a quantum channel; Receive authentication quantum information measurement information related to the value obtained by measuring the authentication quantum information by the receiving end from the receiving end; and Perform user authentication with the receiving end based on the authentication quantum information measurement information.

15. An apparatus including one or more memories and one or more processors, the one or more processors being functionally connected to the one or more memories, Among them, the one or more processors controlling the apparatus: Generate authentication quantum information by encoding an authentication message for user authentication based on a pre-shared key, wherein the basis for encoding each bit element constituting the authentication message is determined based on the corresponding bit value of the bit element constituting the pre-shared key, and the corresponding bit element corresponds to the corresponding position of the bit element constituting the pre-shared key; Send the authentication quantum information to a receiving end via a quantum channel; Receive authentication quantum information measurement information related to the value obtained by measuring the authentication quantum information by the receiving end from the receiving end; and Perform user authentication with the receiving end based on the authentication quantum information measurement information.

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