Method for performing semiquantum secure direct communication without measurement of classical party, and device therefor

Abstract

A method according to an embodiment of the present specification comprises the steps of: receiving photons from a second device; transmitting a qubit sequence generated on the basis of the photons to the second device; receiving, from the second device, measurement information based on the qubit sequence; transmitting, to the second device, information on a quantum bit error rate (QBER) determined on the basis of the measurement information; receiving basis information from the second device; and transmitting information related to a message to the second device.

Description

Method and apparatus for performing semi-quench direct communication without measuring a classical party

[0001] This specification relates to a method and apparatus for performing semiquantum secure direct communication without measurement of classical parties.

[0002] Mobile communication systems were developed to provide voice services while ensuring user mobility. However, mobile communication systems have expanded their scope to include data services as well as voice. Currently, due to the explosive increase in traffic leading to resource shortages and users demanding higher-speed services, more advanced mobile communication systems are required.

[0003] The requirements for next-generation mobile communication systems largely include the ability to accommodate explosive data traffic, a dramatic increase in transmission rates per user, a significantly increased number of connected devices, very low end-to-end latency, and high energy efficiency. To achieve this, various technologies are being researched, such as dual connectivity, massive multiple input multiple output (MMIMO), in-band full duplex, non-orthogonal multiple access (NOMA), super wideband support, and device networking.

[0004] Meanwhile, the Quantum Secure Direct Communication (QSDC) protocol is a protocol that enables the secure transmission of messages using quantum states. However, QSDC can pose an implementation burden in that both the sender and receiver must possess quantum characteristics. To address this, the Semi-Quantum Secure Direct Communication (SQSDC) protocol has been proposed, in which one of the sender or receiver possesses classical characteristics.

[0005] In the case of the side performing the classical role in the aforementioned SQSDC (e.g., the transmitter, Alice), the ability to measure photons is required. For example, the transmitter must be equipped with a measuring device to support such measurement capability.

[0006] The purpose of this specification is to propose a method for performing SQSDC-based communication without measurement of a party having classical characteristics (e.g., sender, Alice).

[0007] The technical problems to be solved in this specification are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this specification belongs from the description below.

[0008] A method according to one embodiment of the present specification comprises the steps of receiving photons from a second device, transmitting a qubit sequence generated based on the photons to the second device, receiving measurement information based on the qubit sequence from the second device, transmitting information regarding a Quantum Bit Error Rate (QBER) determined based on the measurement information to the second device, receiving basis information from the second device, and transmitting information related to a message to the second device.

[0009] The above measurement information includes information related to qubits measured based on the Z basis among the qubits based on the above qubit sequence.

[0010] The above basis information represents the first photons based on the Z basis among the above photons.

[0011] The information related to the above message is characterized by being generated based on i) first photons determined based on the length of the message among the first photons and ii) second photons based on the message.

[0012] The information related to the above message may include i) the determined first photons and ii) a first sequence generated based on the second photons.

[0013] For each of the indices based on the length of the message in the first sequence above, each first photon and each second photon can be arranged in a predetermined order.

[0014] The above-mentioned predetermined order may be a first order in which each first photon is placed first, or a second order in which each second photon is placed first.

[0015] The information related to the above message may include a second sequence related to a hash function. The second sequence may be based on a first output value of the hash function based on the message.

[0016] The message may be estimated based on the information related to the message received by the second device, and each element of the estimated message may be determined based on i) two values ​​based on the measurement of the information related to the message and ii) the sum of one of the determined first photons.

[0017] Based on the fact that the second output value of the hash function based on the above estimated message is different from the first output value, the above estimated message can be determined to be manipulated.

[0018] Based on the fact that the second output value is the same as the first output value, the estimated message can be determined to have been transmitted by the first device.

[0019] The above method may further include the step of transmitting order information related to the generation of the qubit sequence to the second device.

[0020] A sequence having a length of 2n can be generated based on n selected photons among the above photons and n states based on the Z basis. A qubit sequence can be generated based on a reorder of the generated sequence. The order information may indicate the order related to the reorder.

[0021] The above basis information can be received based on the fact that the QBER is less than or equal to the threshold value.

[0022] A protocol based on the photons may be discarded based on the fact that the above QBER is greater than the above threshold.

[0023] The above measurement information may include i) the position of each of the measured qubits in the above qubit sequence and ii) the measurement value for each of the above measured qubits.

[0024] A first device according to another embodiment of the present specification includes one or more transceivers, one or more processors, and one or more memories connected to the one or more processors and storing instructions.

[0025] The above instructions are characterized by setting the one or more processors to perform all steps of any one of the above methods based on execution by the one or more processors.

[0026] One or more non-transitory computer-readable media according to another embodiment of the present specification store instructions. The instructions, executable by one or more processors, are characterized by setting the one or more processors to perform all steps of any one of the methods.

[0027] A method according to another embodiment of the present specification comprises the steps of transmitting photons to a first device, receiving a qubit sequence generated based on the photons from the first device, transmitting measurement information based on the qubit sequence to the first device, receiving information regarding a Quantum Bit Error Rate (QBER) determined based on the measurement information from the first device, transmitting basis information to the first device, and receiving information related to a message from the first device.

[0028] The above measurement information includes information related to qubits measured based on the Z basis among the qubits based on the above qubit sequence.

[0029] The above basis information represents the first photons based on the Z basis among the above photons.

[0030] The information related to the above message is characterized by being generated based on i) first photons determined based on the length of the message among the first photons and ii) second photons based on the message.

[0031] A second device according to another embodiment of the present specification includes one or more transceivers, one or more processors, and one or more memories connected to the one or more processors and storing instructions.

[0032] The above instructions are characterized by setting the one or more processors to perform all steps of the method based on execution by the one or more processors.

[0033] One or more non-transitory computer-readable media according to another embodiment of the present specification store instructions. The instructions, executable by one or more processors, are characterized by setting the one or more processors to perform all steps of the method.

[0034] According to the embodiments of the present specification, SQSDC-based communication can be performed without measurement of the first device. Accordingly, the economic burden or implementation complexity required to implement the SQSDC-based communication can be reduced.

[0035] The effects obtainable in this specification are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art to which this specification belongs from the description below.

[0036] The drawings attached below are intended to aid in understanding the present specification and may provide embodiments of the present specification along with detailed descriptions. However, the technical features of the present specification are not limited to specific drawings, and features disclosed in each drawing may be combined with one another to form new embodiments. Reference numerals in each drawing may denote structural elements.

[0037] FIG. 1 is a drawing showing an example of a communication system applicable to the present specification.

[0038] FIG. 2 is a drawing showing an example of a wireless device applicable to the present specification.

[0039] FIG. 3 is a diagram illustrating a method for processing a transmission signal applicable to the present specification.

[0040] FIG. 4 is a drawing showing another example of a wireless device applicable to the present specification.

[0041] FIG. 5 is a drawing showing an example of a portable device applicable to the present specification.

[0042] FIG. 6 is a diagram showing physical channels applicable to the present specification and a signal transmission method using them.

[0043] FIG. 7 is a drawing showing the structure of a wireless frame applicable to the present specification.

[0044] FIG. 8 is a drawing showing a slot structure applicable to the present specification.

[0045] FIG. 9 is a diagram showing an example of a communication structure that can be provided in a 6G system applicable to the present specification.

[0046] Figure 10 is a diagram showing the basic properties of quantum information.

[0047] Figure 11 is a diagram illustrating a quantum transmission protocol using photons.

[0048] Figure 12 is a diagram illustrating superdense coding.

[0049] FIG. 13 is a diagram illustrating Step 1 and Step 2 of SQSDC according to an embodiment of the present specification.

[0050] FIG. 14 is a diagram illustrating Step 3 of the SQSDC according to an embodiment of the present specification.

[0051] FIG. 15 illustrates a transmission and reception procedure according to an embodiment of the present specification.

[0052] FIG. 16 is a flowchart illustrating a method according to one embodiment of the present specification.

[0053] FIG. 17 is a flowchart illustrating a method according to another embodiment of the present specification.

[0054] The following embodiments are combinations of the components and features of this specification in a predetermined form. Each component or feature may be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, some components and / or features may be combined to constitute the embodiments of this specification. The order of operations described in the embodiments of this specification may be changed. Some components or features of any embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment.

[0055] In the description of the drawings, procedures or steps that could obscure the gist of the specification have not been described, nor have procedures or steps that are understandable to those skilled in the art been described.

[0056] Throughout the specification, when a part is described as "comprising" or "including" a component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as "...part," "...unit," and "module" as used in the specification refer to a unit that performs at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software. Additionally, "one (a or an)," "one," "the," and similar related terms may be used in the context describing this specification (particularly in the context of the following claims) to include both singular and plural forms, unless otherwise indicated in this specification or clearly contradicted by the context.

[0057] The embodiments of this specification have been described with a focus on the data transmission and reception relationship between a base station and a mobile station. Here, the base station refers to a terminal node of a network that communicates directly with a mobile station. Specific operations described herein as being performed by a base station may, in some cases, be performed by an upper node of the base station.

[0058] That is, in a network consisting of multiple network nodes including a base station, various operations performed for communication with a mobile station may be performed by the base station or other network nodes other than the base station. In this case, 'base station' may be replaced by terms such as fixed station, Node B, eNB (eNode B), gNB (gNode B), ng-eNB, advanced base station (ABS), or access point.

[0059] Additionally, in the embodiments of this specification, the term terminal may be replaced with terms such as user equipment (UE), mobile station (MS), subscriber station (SS), mobile subscriber station (MSS), mobile terminal, or advanced mobile station (AMS).

[0060] Furthermore, the transmitting end refers to a fixed and / or mobile node that provides data or voice services, and the receiving end refers to a fixed and / or mobile node that receives data or voice services. Therefore, in the case of the uplink, a mobile station can be the transmitting end and a base station can be the receiving end. Similarly, in the case of the downlink, a mobile station can be the receiving end and a base station can be the transmitting end.

[0061] The embodiments of this specification may be supported by standard documents disclosed in at least one of the wireless access systems, such as IEEE 802.xx systems, 3GPP (3rd Generation Partnership Project) systems, 3GPP LTE (Long Term Evolution) systems, 3GPP 5G (5th generation) NR (New Radio) systems and 3GPP2 systems, and in particular, the embodiments of this specification may be supported by the documents 3GPP TS (technical specification) 38.211, 3GPP TS 38.212, 3GPP TS 38.213, 3GPP TS 38.321 and 3GPP TS 38.331.

[0062] In addition, the embodiments of this specification may be applied to other wireless access systems and are not limited to the systems described above. For example, they may be applicable to systems applied after the 3GPP 5G NR system and are not limited to specific systems.

[0063] That is, obvious steps or parts not described in the embodiments of this specification may be described by referring to the aforementioned documents. Additionally, all terms disclosed in this specification may be explained by the aforementioned standard documents.

[0064] Hereinafter, preferred embodiments according to the present specification will be described in detail with reference to the accompanying drawings. The detailed description disclosed below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present specification and is not intended to represent the only embodiment in which the technical configuration of the present specification can be implemented.

[0065] Additionally, specific terms used in the embodiments of this specification are provided to aid in understanding this specification, and the use of such specific terms may be modified in other forms without departing from the technical spirit of this specification.

[0066] The following technology can be applied to various wireless access systems such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access).

[0067] For the sake of clarity in the following description, the explanation is based on 3GPP communication systems (e.g., LTE, NR, etc.), but the technical concept of the present invention is not limited thereto. LTE may refer to technology from 3GPP TS 36.xxx Release 8 onwards. Specifically, LTE technology from 3GPP TS 36.xxx Release 10 onwards is referred to as LTE-A, and LTE technology from 3GPP TS 36.xxx Release 13 onwards may be referred to as LTE-A pro. 3GPP NR may refer to technology from TS 38.xxx Release 15 onwards. 3GPP 6G may refer to technology from TS Release 17 and / or Release 18 onwards. "xxx" indicates a standard document detail number. LTE / NR / 6G may be collectively referred to as 3GPP systems.

[0068] Regarding the background technology, terms, abbreviations, etc. used in this specification, reference may be made to matters described in standard documents published prior to the present invention. For example, reference may be made to standard documents 36.xxx and 38.xxx.

[0069] Communication systems applicable to the present specification

[0070] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this specification may be applied to various fields requiring wireless communication / connection (e.g., 5G) between devices.

[0071] Examples are provided in more detail below with reference to the drawings. In the following drawings and descriptions, the same reference numerals may represent the same or corresponding hardware blocks, software blocks, or function blocks unless otherwise described.

[0072] FIG. 1 is a drawing illustrating an example of a communication system to which the present specification applies. Referring to FIG. 1, the communication system (100) to which the present specification applies includes a wireless device, a base station, and a network. Here, a wireless device refers to a device that performs communication using wireless access technology (e.g., 5G NR, LTE) and may be referred to as a communication / wireless / 5G device. Although not limited thereto, a wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (extended reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Thing) device (100f), and an AI (artificial intelligence) device / server (100g). For example, a vehicle may include a vehicle equipped with wireless communication capabilities, an autonomous vehicle, a vehicle capable of performing inter-vehicle communication, etc. Here, the vehicle (100b-1, 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) equipped in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, digital signage, a vehicle, a robot, etc. The portable device (100d) may include a smartphone, a smart pad, a wearable device (e.g., a smartwatch, smart glasses), a computer (e.g., a laptop, etc.). The home appliance (100e) may include a TV, 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 network (130) may also be implemented as wireless devices, and a specific wireless device (120a) may act as a base station / network node for other wireless devices.

[0073] Wireless devices (100a to 100f) can be connected to a network (130) through a base station (120). AI technology may be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (100g) through the network (130). The network (130) can be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. The wireless devices (100a to 100f) may communicate with each other through the base station (120) / network (130), but they may also communicate directly (e.g., sidelink communication) without going through the base station (120) / network (130). For example, vehicles (100b-1, 100b-2) can communicate directly (e.g., V2V (vehicle to vehicle) / V2X (vehicle to everything) communication). Also, IoT devices (100f) (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

[0074] Wireless communication / connection (150a, 150b, 150c) can be established between wireless devices (100a~100f) / base station (120) and between base station (120) / base station (120). Here, wireless communication / connection can be established through various wireless access technologies (e.g., 5G NR), such as uplink / downlink communication (150a), sidelink communication (150b) (or D2D communication), and communication between base stations (150c) (e.g., relay, IAB (integrated access backhaul)). Through wireless communication / connection (150a, 150b, 150c), wireless devices and base stations / wireless devices, and base stations and base stations can transmit / receive wireless signals to / from each other. For example, wireless communication / connection (150a, 150b, 150c) can transmit / receive signals through various physical channels. To this end, based on the various proposals of this specification, at least some of the following may be performed: a process for setting various configuration information for transmitting / receiving wireless signals, a process for various signal processing (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), a resource allocation process, etc.

[0075] Communication systems applicable to the present specification

[0076] FIG. 2 is a drawing illustrating an example of a wireless device that can be applied to the present specification.

[0077] Referring to FIG. 2, the first wireless device (200a) and the second wireless device (200b) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device (200a), the second wireless device (200b)} may correspond to {the wireless device (100x), the base station (120)} and / or {the wireless device (100x), the wireless device (100x)} of FIG. 1.

[0078] The first wireless device (200a) includes one or more processors (202a) and one or more memories (204a), and may additionally include one or more transceivers (206a) and / or one or more antennas (208a). The processor (202a) controls the memory (204a) and / or transceivers (206a) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed herein. For example, the processor (202a) may process information within the memory (204a) to generate a first information / signal and then transmit a wireless signal containing the first information / signal through the transceiver (206a). Additionally, the processor (202a) may receive a wireless signal containing a second information / signal through the transceiver (206a) and then store information obtained from the signal processing of the second information / signal in the memory (204a). Memory (204a) may be connected to the processor (202a) and may store various information related to the operation of the processor (202a). For example, memory (204a) may store software code including instructions for performing some or all of the processes controlled by the processor (202a) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequences of operation disclosed in this specification. Here, the processor (202a) and memory (204a) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). A transceiver (206a) may be connected to the processor (202a) and may transmit and / or receive wireless signals through one or more antennas (208a). The transceiver (206a) may include a transmitter and / or receiver. The transceiver (206a) may be combined with an RF (radio frequency) unit. In this specification, a wireless device may refer to a communication modem / circuit / chip.

[0079] The second wireless device (200b) includes one or more processors (202b) and one or more memories (204b), and may additionally include one or more transceivers (206b) and / or one or more antennas (208b). The processor (202b) controls the memory (204b) and / or transceivers (206b) and may be configured to implement the descriptions, functions, procedures, proposals, methods and / or sequences of operation disclosed herein. For example, the processor (202b) may process information within the memory (204b) to generate a third information / signal and then transmit a wireless signal containing the third information / signal through the transceiver (206b). Additionally, the processor (202b) may receive a wireless signal containing a fourth information / signal through the transceiver (206b) and then store information obtained from the signal processing of the fourth information / signal in the memory (204b). The memory (204b) may be connected to the processor (202b) and may store various information related to the operation of the processor (202b). For example, the memory (204b) may store software code including instructions for performing some or all of the processes controlled by the processor (202b) or for performing the descriptions, functions, procedures, proposals, methods, and / or sequence diagrams of operation disclosed in this specification. Here, the processor (202b) and the memory (204b) may be part of a communication modem / circuit / chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206b) may be connected to the processor (202b) and may transmit and / or receive wireless signals through one or more antennas (208b). The transceiver (206b) may include a transmitter and / or receiver. The transceiver (206b) may be used in combination with an RF unit. In this specification, a wireless device may refer to a communication modem / circuit / chip.

[0080] Hereinafter, hardware elements of the wireless device (200a, 200b) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (202a, 202b). For example, one or more processors (202a, 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), and SDAP (service data adaptation protocol). One or more processors (202a, 202b) may generate one or more PDUs (Protocol Data Units) and / or one or more SDUs (service data units) according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed herein. One or more processors (202a, 202b) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this specification. One or more processors (202a, 202b) may generate a signal (e.g., baseband signal) including a PDU, SDU, message, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this specification and provide it to one or more transceivers (206a, 206b). One or more processors (202a, 202b) may receive a signal (e.g., baseband signal) from one or more transceivers (206a, 206b) and may obtain a PDU, SDU, message, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed in this specification.

[0081] One or more processors (202a, 202b) may be referred to as a controller, microcontroller, microprocessor, or microcomputer. One or more processors (202a, 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), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in one or more processors (202a, 202b). Descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed herein may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this specification may be included in one or more processors (202a, 202b) or stored in one or more memories (204a, 204b) and driven by one or more processors (202a, 202b). The descriptions, functions, procedures, proposals, methods, and / or operation sequences disclosed in this specification may be implemented using firmware or software in the form of code, instructions, and / or sets of instructions.

[0082] One or more memories (204a, 204b) may be connected to one or more processors (202a, 202b) and may store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. One or more memories (204a, 204b) may be composed of ROM (read-only memory), RAM (random access memory), EPROM (erasable programmable read-only memory), flash memory, hard drives, registers, cache memory, computer-readable storage media, and / or combinations thereof. One or more memories (204a, 204b) may be located inside and / or outside of one or more processors (202a, 202b). Additionally, one or more memories (204a, 204b) may be connected to one or more processors (202a, 202b) through various technologies such as wired or wireless connections.

[0083] One or more transceivers (206a, 206b) may transmit user data, control information, wireless signals / channels, etc., as mentioned in the methods and / or operation flowcharts, etc., of this specification to one or more other devices. One or more transceivers (206a, 206b) may receive user data, control information, wireless signals / channels, etc., as mentioned in the descriptions, functions, procedures, proposals, methods and / or operation flowcharts, etc., disclosed in this specification from one or more other devices. For example, one or more transceivers (206a, 206b) may be connected to one or more processors (202a, 202b) and may transmit and receive wireless signals. For example, one or more processors (202a, 202b) may control one or more transceivers (206a, 206b) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (202a, 202b) may control one or more transceivers (206a, 206b) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (206a, 206b) may be connected to one or more antennas (208a, 208b), and one or more transceivers (206a, 206b) may be configured to transmit and receive user data, control information, wireless signals / channels, etc., as described in the descriptions, functions, procedures, proposals, methods, and / or flowcharts of operation disclosed herein through one or more antennas (208a, 208b). In this specification, one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports). One or more transceivers (206a, 206b) can convert the received wireless signal / channel, etc. from an RF band signal to a baseband signal in order to process the received user data, control information, wireless signal / channel, etc. using one or more processors (202a, 202b).One or more transceivers (206a, 206b) can convert user data, control information, wireless signals / channels, etc. processed using one or more processors (202a, 202b) from baseband signals to RF band signals. To this end, one or more transceivers (206a, 206b) may include (analog) oscillators and / or filters.

[0084] FIG. 3 is a diagram illustrating a method for processing a transmission signal applicable to the present specification. For example, the transmission signal may be processed by a signal processing circuit. In this case, the signal processing circuit (300) may include a scrambler (310), a modulator (320), a layer mapper (330), a precoder (340), a resource mapper (350), and a signal generator (360). In this case, for example, the operation / function of FIG. 3 may be performed in the processor (202a, 202b) and / or transceiver (206a, 206b) of FIG. 2. Also, for example, the hardware element of FIG. 3 may be implemented in the processor (202a, 202b) and / or transceiver (206a, 206b) of FIG. 2. For example, blocks 310 to 350 may be implemented in the processor (202a, 202b) of FIG. 2, and block 360 may be implemented in the transceiver (206a, 206b) of FIG. 2, but are not limited to the above-described embodiment.

[0085] A codeword can be converted into a wireless signal through the signal processing circuit (300) of FIG. 3. Here, the codeword is an encoded bit sequence of an information block. The information block may include a transmission block (e.g., UL-SCH transmission block, DL-SCH transmission block). The wireless signal may be transmitted through various physical channels (e.g., PUSCH, PDSCH) of FIG. 6. Specifically, the codeword can be converted into a scrambled bit sequence by a scrambler (310). The scrambled sequence used for scrambling is generated based on an initialization value, which may include ID information of a wireless device, etc. The scrambled bit sequence may be modulated into a modulation symbol sequence by a modulator (320). The modulation method may include pi / 2-BPSK (pi / 2-binary phase shift keying), m-PSK (m-phase shift keying), m-QAM (m-quadrature amplitude modulation), etc.

[0086] A complex modulation symbol sequence can be mapped to one or more transmission layers by a layer mapper (330). The modulation symbols of each transmission layer can be mapped to the corresponding antenna port(s) by a precoder (340) (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, where N is the number of antenna ports and M is the number of transmission layers. Here, the precoder (340) can perform precoding after performing transform precoding (e.g., a discrete Fourier transform (DFT)) on the complex modulation symbols. Alternatively, the precoder (340) can perform precoding without performing transform precoding.

[0087] A resource mapper (350) can map the modulation symbols of each antenna port to a time-frequency resource. The time-frequency resource may include multiple symbols (e.g., CP-OFDMA symbols, DFT-s-OFDMA symbols) in the time domain and multiple subcarriers in the frequency domain. A signal generator (360) generates a radio signal from the mapped modulation symbols, and the generated radio signal can be transmitted to another device through each antenna. To this end, the signal generator (360) may include an inverse fast Fourier transform (IFFT) module, a cyclic prefix (CP) inserter, a digital-to-analog converter (DAC), a frequency uplink converter, etc.

[0088] The signal processing process for a received signal in a wireless device can be configured as the inverse of the signal processing process (310–360) of FIG. 3. For example, a wireless device (e.g., 200a, 200b of FIG. 2) can receive a wireless signal from the outside through an antenna port / transceiver. The received wireless signal can be converted into a baseband signal through a signal restorer. To this end, the signal restorer may include a frequency downlink converter, an analog-to-digital converter (ADC), a CP remover, and a fast Fourier transform (FFT) module. Subsequently, the baseband signal can be restored into a codeword through a resource de-mapper process, a postcoding process, a demodulation process, and a de-scrambling process. The codeword can be restored into the original information block through decoding. Accordingly, a signal processing circuit (not shown) for a received signal may include a signal restorer, a resource de-mapper, a postcoder, a demodulator, a de-scrambler, and a decoder.

[0089] Wireless device structure applicable to the present specification

[0090] FIG. 4 is a drawing illustrating another example of a wireless device to which the present specification applies.

[0091] Referring to FIG. 4, the wireless device (400) corresponds to the wireless device (200a, 200b) of FIG. 2 and may be composed of various elements, components, units / parts, and / or modules. For example, the wireless device (400) may include a communication unit (410), a control unit (420), a memory unit (430), and additional elements (440). The communication unit may include a communication circuit (412) and transceiver(s) (414). For example, the communication circuit (412) may include one or more processors (202a, 202b) and / or one or more memories (204a, 204b) of FIG. 2. For example, the transceiver(s) (414) may include one or more transceivers (206a, 206b) and / or one or more antennas (208a, 208b) of FIG. 2. The control unit (420) is electrically connected to the communication unit (410), the memory unit (430), and additional elements (440) and controls the general operation of the wireless device. For example, the control unit (420) may control the electrical / mechanical operation of the wireless device based on a program / code / command / information stored in the memory unit (430). Additionally, the control unit (420) may transmit information stored in the memory unit (430) to an external (e.g., another communication device) via a wireless / wired interface through the communication unit (410), or store information received from an external (e.g., another communication device) via a wireless / wired interface through the communication unit (410) in the memory unit (430).

[0092] The additional element (440) can be configured in various ways depending on the type of wireless device. For example, the additional element (440) may include at least one of a power unit / battery, an input / output unit, a driving unit, and a computing unit. Although not limited thereto, the wireless device (400) may be implemented in the form of a robot (Fig. 1, 100a), a vehicle (Fig. 1, 100b-1, 100b-2), an XR device (Fig. 1, 100c), a portable device (Fig. 1, 100d), a home appliance (Fig. 1, 100e), an IoT device (Fig. 1, 100f), a digital broadcasting terminal, a hologram device, a public safety device, an MTC device, a medical device, a fintech device (or financial device), a security device, a climate / environment device, an AI server / device (Fig. 1, 140), a base station (Fig. 1, 120), a network node, etc. Wireless devices can be used in a movable or fixed location depending on the use—e.g., service.

[0093] In FIG. 4, various elements, components, units / parts, and / or modules within the wireless device (400) may be entirely interconnected via a wired interface, or at least partially connected via a communication unit (410). For example, within the wireless device (400), the control unit (420) and the communication unit (410) may be connected via a wire, and the control unit (420) and the first unit (e.g., 430, 440) may be connected wirelessly via the communication unit (410). Additionally, each element, component, unit / part, and / or module within the wireless device (400) may include one or more additional elements. For example, the control unit (420) may be composed of one or more sets of processors. For example, the control unit (420) may be composed of a set of a communication control processor, an application processor, an electronic control unit (ECU), a graphics processing processor, a memory control processor, etc. As another example, the memory unit (430) may be composed of RAM, DRAM (dynamic RAM), ROM, flash memory, volatile memory, non-volatile memory and / or a combination thereof.

[0094] Mobile devices to which this specification applies

[0095] FIG. 5 is a drawing illustrating an example of a portable device to which the present specification applies.

[0096] FIG. 5 illustrates a portable device to which the present specification applies. The portable device may include a smartphone, a smartpad, a wearable device (e.g., a smart watch, smart glasses), a portable computer (e.g., a laptop, etc.). The portable device may be referred to as an MS (mobile station), UT (user terminal), MSS (mobile subscriber station), SS (subscriber station), AMS (advanced mobile station), or WT (wireless terminal).

[0097] Referring to FIG. 5, the portable device (500) may include an antenna unit (508), a communication unit (510), a control unit (520), a memory unit (530), a power supply unit (540a), an interface unit (540b), and an input / output unit (540c). The antenna unit (508) may be configured as part of the communication unit (510). Blocks 510 to 530 / 540a to 540c correspond to blocks 410 to 430 / 440 of FIG. 4, respectively.

[0098] The communication unit (510) can transmit and receive signals (e.g., data, control signals, etc.) with other wireless devices and base stations. The control unit (520) can control the components of the portable device (500) to perform various operations. The control unit (520) may include an application processor (AP). The memory unit (530) can store data / parameters / programs / code / commands required for the operation of the portable device (500). Additionally, the memory unit (530) can store input / output data / information, etc. The power supply unit (540a) supplies power to the portable device (500) and may include wired / wireless charging circuits, batteries, etc. The interface unit (540b) can support the connection between the portable device (500) and other external devices. The interface unit (540b) may include various ports (e.g., audio input / output ports, video input / output ports) for connection with external devices. The input / output unit (540c) can receive or output video information / signals, audio information / signals, data, and / or information input from a user. The input / output unit (540c) may include a camera, a microphone, a user input unit, a display unit (540d), a speaker and / or a haptic module, etc.

[0099] For example, in the case of data communication, the input / output unit (540c) acquires information / signals (e.g., touch, text, voice, image, video) input by the user, and the acquired information / signals can be stored in the memory unit (530). The communication unit (510) converts the information / signals stored in the memory into wireless signals and can directly transmit the converted wireless signals to another wireless device or to a base station. Additionally, the communication unit (510) can receive wireless signals from another wireless device or base station and then restore the received wireless signals to their original information / signals. The restored information / signals are stored in the memory unit (530) and then can be output in various forms (e.g., text, voice, image, video, haptic) through the input / output unit (540c).

[0100] Physical channels and general signal transmission

[0101] In a wireless access system, a terminal can receive information from a base station via a downlink (DL) and transmit information to a base station via an uplink (UL). The information transmitted and received by the base station and the terminal includes general data information and various control information, and various physical channels exist depending on the type and purpose of the information they transmit and receive.

[0102] FIG. 6 is a diagram illustrating physical channels applicable to the present specification and a signal transmission method using them.

[0103] When a terminal is turned on again after being turned off, or when it newly enters a cell, it performs initial cell search operations, such as synchronizing with the base station, in step S611. To do this, the terminal receives the primary synchronization channel (P-SCH) and secondary synchronization channel (S-SCH) from the base station to synchronize with the base station and obtain information such as the cell ID.

[0104] Subsequently, the terminal can obtain in-cell broadcast information by receiving a physical broadcast channel (PBCH) signal from the base station. Meanwhile, during the initial cell search phase, the terminal can check the downlink channel status by receiving a Downlink Reference Signal (DL RS). After completing the initial cell search, the terminal can obtain more specific system information by receiving the physical downlink control channel (PDCCH) and the physical downlink shared channel (PDSCH) based on the physical downlink control channel information in step S612.

[0105] Subsequently, the terminal may perform a random access procedure, such as steps S613 through S616, to complete the connection to the base station. To this end, the terminal transmits a preamble through a physical random access channel (PRACH) (S613) and receives a random access response (RAR) for the preamble through a physical downlink control channel and a corresponding physical downlink shared channel (S614). The terminal transmits a physical uplink shared channel (PUSCH) using scheduling information within the RAR (S615) and performs a contention resolution procedure, such as receiving a physical downlink control channel signal and a corresponding physical downlink shared channel signal (S616).

[0106] A terminal that has performed the procedure described above may subsequently 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 procedure.

[0107] Control information transmitted by a terminal to a base station is collectively referred to as uplink control information (UCI). UCI includes HARQ-ACK / NACK (hybrid automatic repeat and request acknowledgment / negative-ACK), SR (scheduling request), CQI (channel quality indication), PMI (precoding matrix indication), RI (rank indication), BI (beam indication) information, etc. In this case, UCI is generally transmitted periodically via PUCCH, but depending on the embodiment (e.g., when control information and traffic data need to be transmitted simultaneously), it may be transmitted via PUSCH. Additionally, the terminal may transmit UCI non-periodically via PUSCH in response to a request or instruction from the network.

[0108] FIG. 7 is a drawing illustrating the structure of a wireless frame applicable to the present specification.

[0109] Uplink and downlink transmission based on an NR system may be based on frames such as those shown in FIG. 7. In this case, one wireless frame has a length of 10 ms and can be defined as two 5 ms half-frames (HF). One half-frame can be defined as five 1 ms subframes (SF). One subframe is divided into one or more slots, and the number of slots within a subframe may depend on the subcarrier spacing (SCS). In this case, each slot may contain 12 or 14 OFDM(A) symbols according to the cyclic prefix (CP). When a normal CP is used, each slot may contain 14 symbols. When an extended CP is used, each slot may contain 12 symbols. Here, the symbols may include OFDM symbols (or CP-OFDM symbols) or SC-FDMA symbols (or DFT-s-OFDM symbols).

[0110] Table 1 shows the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to SCS when a standard CP is used, and Table 2 shows the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to SCS when an extended CSP is used.

[0111]

[0112]

[0113] In Tables 1 and 2 above, Nslotsymb represents the number of symbols in a slot, Nframe,μslot represents the number of slots in a frame, and Nsubframe,μslot represents the number of slots in a subframe.

[0114] In addition, in a system to which this specification applies, the OFDM(A) numerology (e.g., SCS, CP length, etc.) may be configured differently among multiple cells merged into a single terminal. Accordingly, the (absolute time) interval of a time resource (e.g., SF, slot, or TTI) (collectively referred to as TU (time unit) for convenience) composed of the same number of symbols may be configured differently among the merged cells.

[0115] NR can support multiple numerologies (or subcarrier spacing (SCS)) to support various 5G services. For example, if the SCS is 15 kHz, it supports a wide area in traditional cellular bands; if the SCS is 30 kHz / 60 kHz, it supports dense-urban, lower latency, and wider carrier bandwidth; and if the SCS is 60 kHz or higher, it can support a bandwidth greater than 24.25 GHz to overcome phase noise.

[0116] The NR frequency band is defined by two types of frequency ranges (FR1, FR2). FR1 and FR2 can be configured as shown in the table below. Additionally, FR2 may refer to millimeter wave (mmW).

[0117]

[0118] In addition, as an example, the numerology described above may be configured differently in a communication system to which this specification is applicable. As an example, a terahertz wave (THX) band may be used as a frequency band higher than the FR2 described above. In the THz band, the SCS may be configured larger than in the NR system, and the number of slots may be configured differently, and is not limited to the embodiments described above.

[0119] FIG. 8 is a drawing illustrating a slot structure applicable to the present specification.

[0120] A single slot contains multiple symbols in the time domain. For example, in the case of a standard CP, a single slot contains 7 symbols, but in the case of an extended CP, a single slot may contain 6 symbols. A carrier contains multiple subcarriers in the frequency domain. A resource block (RB) can be defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain.

[0121] Additionally, a Bandwidth Part (BWP) is defined as a plurality of consecutive (P)RBs in the frequency domain and can correspond to a single numerology (e.g., SCS, CP length, etc.).

[0122] A carrier wave may contain up to N (e.g., 5) BWPs. Data communication is performed through the active BWPs, and only one BWP can be active for a single terminal. In the resource grid, each element is referred to as a resource element (RE), and a single complex symbol can be mapped to it.

[0123] 6G communication system

[0124] The 6G (wireless communication) system aims for (i) very high data rates per device, (ii) a very large number of connected devices, (iii) global connectivity, (iv) very low latency, (v) reduced energy consumption of battery-free IoT devices, (vi) ultra-reliable connectivity, and (vii) connected intelligence with machine learning capabilities. The vision of the 6G system can be seen in four aspects, such as "intelligent connectivity," "deep connectivity," "holographic connectivity," and "ubiquitous connectivity," and the 6G system can satisfy the requirements shown in Table 4 below. In other words, Table 4 represents the requirements of the 6G system.

[0125]

[0126] At this time, 6G systems can have key factors such as enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLC), mMTC (massive machine type communications), AI integrated communication, tactile internet, high throughput, high network capacity, high energy efficiency, low backhaul and access network congestion, and enhanced data security.

[0127] FIG. 9 is a drawing illustrating an example of a communication structure that can be provided in a 6G system applicable to the present specification.

[0128] Referring to Fig. 9, the 6G system is expected to have simultaneous wireless connectivity 50 times higher than the 5G wireless communication system. URLLC, a key feature of 5G, is expected to become an even more dominant technology in 6G communication by providing end-to-end latency of less than 1ms. In this case, the 6G system will exhibit significantly superior volumetric spectrum efficiency, unlike the frequently used area spectrum efficiency. The 6G system can provide very long battery life and advanced battery technology for energy harvesting, so mobile devices in the 6G system may not need to be charged separately. Additionally, new network characteristics in 6G may be as follows.

[0129] - Satellite Integrated Network: 6G is expected to be integrated with satellites to provide a global mobile population. Integrating terrestrial, satellite, and airborne networks into a single wireless communication system could be very important for 6G.

[0130] - Connected Intelligence: Unlike previous generations of wireless communication systems, 6G is innovative and will update wireless evolution from “connected things” to “connected intelligence.” AI can be applied at each stage of the communication process (or at each step of the signal processing described below).

[0131] - Seamless integration of wireless information and energy transfer: 6G wireless networks will transfer power to charge the batteries of devices such as smartphones and sensors. Therefore, wireless information and energy transfer (WIET) will be integrated.

[0132] - Ubiquitous Super 3D Connectivity: Access to the network and core network functions of drones and very low Earth orbit satellites will create Super 3D connectivity in 6G ubiquitous.

[0133] Some general requirements regarding the new network characteristics of 6G mentioned above may be as follows.

[0134] - Small cell networks: The idea of ​​small cell networks was introduced to improve the quality of received signals in cellular systems as a result of increased throughput, energy efficiency, and spectrum efficiency. Consequently, small cell networks are an essential feature of communication systems for 5G and beyond 5G (5GB). Therefore, 6G communication systems also adopt the characteristics of small cell networks.

[0135] - Ultra-dense heterogeneous network: Ultra-dense heterogeneous networks will be another important characteristic of 6G communication systems. Multi-tier networks composed of heterogeneous networks improve overall QoS and reduce costs.

[0136] - High-capacity backhaul: Backhaul connections are characterized as high-capacity backhaul networks to support high-volume traffic. High-speed fiber optics and free-space optics (FSO) systems can be possible solutions to this problem.

[0137] - Radar technology integrated with mobile technology: High-precision localization (or location-based services) through communication is one of the functions of 6G wireless communication systems. Therefore, radar systems will be integrated with 6G networks.

[0138] - Softwarization and virtualization: Softwarization and virtualization are two important features that form the basis of the design process in 5GB networks to ensure flexibility, reconfigurability, and programmability. Additionally, billions of devices can be shared across a shared physical infrastructure.

[0139] The contents examined above may be applied in combination with the methods proposed in this specification described below, or may be supplemented to clarify the technical features of the methods proposed in this specification. The methods described below are distinguished merely for the convenience of explanation, and it goes without saying that parts of any one method may be substituted with parts of another method or combined with one another.

[0140] The symbols / abbreviations / terms used in this specification are as follows.

[0141] - SQSDC: Semi Quantum Secure Direct Communication

[0142] - QSDC: Quantum Secure Direct Communication

[0143] - QBER: Quantum Bit Error Rate

[0144] - Alice : Sender

[0145] - Bob : Recipient

[0146] - Charlie : Detector

[0147] - BS : Beam splitter

[0148] - SPD: Single Photon Detector

[0149] - BSM: Bell state Measurement

[0150] - QKD: Quantum Key Distribution

[0151] This specification relates to a method for implementing a Semiquantum Secure Direct Communication (SQSDC) protocol in a classical party without measurement.

[0152] Below, the background related to the embodiments of the present specification is explained in detail.

[0153] Entanglement

[0154] Classical computers have an internal processing unit, and the basic unit of computation is the bit, which exists in two states: 0 and 1. Meanwhile, in quantum mechanics, multiple states can be superimposed on a single quantum, and quantum computers utilizing this principle are being researched. The quantum bit used in quantum computers is referred to as a qubit (quantum bit) to distinguish it from the bits of classical computers. In other words, a single quantum can possess both a 0 state and a 1 state. However, when measuring a quantum in a superposition state, it decays into one of the superimposed states, resulting in a state of either 0 or 1.

[0155] Therefore, to represent a qubit, a method to represent superimposed quantum states is required. One method that can be used to represent quantum states is Dirac notation. Dirac notation can also be referred to as bra-ket notation.

[0156] Ket can represent the quantum state Ψ and can be expressed in the form |Ψ〉. Bra represents the complex conjugate transpose of Ket and can be expressed in the form <φ|. Therefore, <φ| and |φ〉 form a complex conjugate transpose relationship.

[0157] The inner product between two states can be calculated by combining Bra-kets. For example, the inner product between two states |Ψ〉 and |φ〉 can be expressed in the form <Ψ|φ〉. Furthermore, it can be assumed that all quantum states are normalized. That is, a set of state functions satisfying <Ψ|Ψ〉=1 can be defined. This set is defined as a Hilbert space. Additionally, two quantum states in a Hilbert space for which the Bra-ket result is 0 can be defined as orthogonal. Therefore, when <Ψ|φ〉=0, the relationship between the |Ψ〉 state and the |φ〉 state is orthogonal.

[0158] Entanglement is a property that plays a very important role in distinguishing quantum systems from classical information. Entanglement refers to a state in which the results of different observations are closely related to each other. The entangled state in a quantum system acts more strongly than any correlation existing in classical mechanics. Two qubits can be represented in Hilbert space as a superposition of four fundamental quantum states. Here, the aforementioned four fundamental quantum states are It includes. The fundamental quantum states of two qubits can be represented through tensor operations on the fundamental states of individual qubits. When the states of two qubits cannot be represented by the tensor product of a single qubit, such qubit states are called entangled states. As representative examples of entangled qubits, there are four cases referred to as EPR (Einstein-Podolsky-Rosen) states, which are given by Equation 1 below.

[0159]

[0160] The above EPR state is also called the Bell state, and in each qubit, the measurement result of the qubit located ahead always affects the measurement of the qubit located behind. In addition, the above four Pure States are all Maximally Entangled States and constitute the vertical basis of the 2-qubit Hilbert Space.

[0161] For entangled qubits with M > 2 qubits or more, the GHZ state is as follows.

[0162]

[0163] When M=2 It becomes a Bell State, and generally, the GHZ State is expressed for M=3. Sometimes, the GHZ State can be extended to be expressed as a system corresponding to d-dimension rather than 2-dimension.

[0164] Figure 10 is a diagram showing the basic properties of quantum information.

[0165] Decay of quantum information by measurement

[0166] Quantum information exists probabilistically, and at the moment of measurement, it decays into the ground state and cannot be restored to its state prior to measurement. The measurement of quantum information by the measurement operator is explained in more detail. Quantum information after measurement is probabilistic. and Depending on the, it collapses into one of the underlying states that make up the information. The collapsed information does not contain the information of 'a' or 'b' and cannot return to the state before measurement.

[0167] From the perspective of quantum error correction codes, applying them in a quantum information system requires that codewords be generated without measuring the information during the encoding and restoration process, or without measurements that would alter the information, and that the information be restored after estimating the errors that occurred in the channel. In this process, continuously occurring quantum errors are digitized through measurements for error estimation.

[0168] Quantum Teleportation (QT)

[0169] Quantum teleportation is a technology that transmits quantum information from a sender at a specific location to a receiver located at a certain distance. Unlike the original meaning of the word 'teleport,' in quantum teleportation, the carriers on both sides remain fixed, and instead of the actual transmission of carriers, the transmission of quantum information between carriers takes place. To facilitate this information transmission, an entangled quantum state, or Bell State, is required, which establishes a statistical correlation between distinct physical systems. Because the other particle undergoes the same change for every change experienced by the other particle in an entangled relationship, the two particles behave as if they were a single quantum state.

[0170] Figure 11 is a diagram illustrating a quantum transmission protocol using photons.

[0171] Referring to FIG. 11, for quantum transmission, resources are required for a classical channel capable of transmitting two classical bits, a Bell State (entanglement state) generation device, a quantum channel for moving two particles in the Bell State to a transmitting and receiving end located at different positions, a Bell State measurement device at the transmitting end, and a unitary operation device at the receiving end. Quantum information to be transmitted The operation of the protocol for is as follows.

[0172] [1] Entanglement Generation: Generates the entanglement state of two qubits through a Bell State generator.

[0173] [2] Entanglement Distribution: The generated entanglement state is transferred through a quantum channel, with one qubit moving to the location of sender Alice (A) and the other qubit moving to the location of receiver Bob (B).

[0174] [3] Quantum Pre-processing: Alice wants to transmit the quantum state A Bell State Measurement is performed on one of the Qubits in the Bell State that the user possesses, and a result corresponding to one of the four Bell States is obtained. At this time, the state of the Qubit that Bob possesses may change according to Alice's Bell State Measurement result as shown in Table 5 below. Specifically, Table 5 illustrates the change in Bob's Qubit based on Alice's Bell State Measurement result.

[0175]

[0176] [4] Classical Transmission: Alice encodes the Bell State Measurement results into two classical bits and transmits them to Bob through the classical channel.

[0177] [5] Quantum Post-processing: Based on the two bits of information received from Alice, Bob performs a unitary operation on the remaining qubit of the Bell State he has to obtain the quantum information Alice wanted to send. Obtain the same quantum state as.

[0178] Quantum Direct Communication (QDC)

[0179] Quantum Direct Communication shares similarities with Quantum Key Distribution (QKD), which is used as a 4 / 5G secure communication technology, in that it is a technique for securely transmitting classical message information. However, while QKD is a method of sharing symmetric secret key information, which is necessary to securely transmit message information sent over a classical channel, between the sender and receiver via a quantum channel using the quantum mechanical property of being unclonable, QDC differs in that it is a method of sharing classical message information to be transmitted directly via a quantum channel, rather than a secret key.

[0180] The QDC technology group includes Quantum Secure Direct Communication (QSDC), which has the advantage of guaranteeing high security by not generating leakage information related to transmitted information, and largely includes the Two-step QSDC technique utilizing entangled light sources. This will be explained in detail below with reference to Fig. 12.

[0181] Figure 12 is a diagram illustrating superdense coding. Two-step QSDC is a technique derived from superdense coding as shown in Figure 12. Specifically, Two-step QSDC is a technique that securely transmits 2 bits of classical information using four types of single entangled photons (EPR-pairs) of Equation 2 below.

[0182]

[0183] Superdense coding is a technique that enables the transmission of classical information using quantum communication. When using superdense coding, a transmitter can send 2 bits of classical information to a distant receiver via a quantum channel using a single qubit. When using superdense coding, it is assumed that the transmitter possesses the first qubit in the entangled state, and the receiver possesses the second qubit in the entangled state. There are four possible cases for the qubit that the transmitter intends to transmit: '00', '01', '10', and '11'. For these four cases, the transmitter performs qubit operations (expressed in the form of I, Z, X, and iY) corresponding to each of the four cases on the entangled qubit it possesses, and then transmits the information through the quantum channel. Each operation performed by the transmitter can be understood as serving to transform the entangled state shared by the transmitter and receiver into a different basis that is orthogonal to each other. The receiving end measures the received qubit and the qubit it owns (the second qubit in the entangled state) to recover the 2 bits of information transmitted by the transmitting end.

[0184] Referring to FIG. 12, SR (Storage lines) 1 to 4 are optical delay lines that serve as quantum memory, CE (Checking Eavesdropping) 1 and 2 check for the presence of an eavesdropper, CM (Coding Message) encodes classical message information to be transmitted from the transmitter (Alice) to the receiver (Bob), EPR- source generates an entangled light source, and Bell state measurement measures entangled photon pairs.

[0185] In two-step QSDC, unlike super dense coding, entangled photon pairs are not transmitted all at once to ensure security, but are divided into two stages and transmitted through an upper quantum channel and a down quantum channel. Since eavesdropping on an entangled light source requires knowing the information from both sides of the entangled photon pair to determine the transmitted information through measurement, the two-step technique uses a method in which one side of the entangled photon pair is sent first to verify security against eavesdropping, and only when security is guaranteed is the message information to be sent coded into the remaining part of the photon pair and transmitted.

[0186] The problem to be solved by the present specification is as follows.

[0187] SQSDC that does not require measuring equipment

[0188] The SQSDC protocol is a method that enables the QSDC protocol to be executed in a situation where the receiver has quantum capabilities and the sender has only classical capabilities. The SQSDC protocol is a protocol that is expected to provide advantages in implementation because not all participants in the communication need to possess quantum capabilities.

[0189] The classical party of the SQSDC protocol must have the ability to perform measurements, but if it can execute the protocol without measurements, its configuration can be expected to be much simpler.

[0190] < SemiQuantum Secure Direct Communication >

[0191] The existing SQSDC protocol is explained in detail below.

[0192] The SQSDC protocol proceeds as follows based on Step 1, Step 2, and Step 3.

[0193] ① Step 1: Transmission Step

[0194] Bob is Prepare polarized single photons and send them to Alice.

[0195] Here, n is based on the following mathematical formula 3.

[0196]

[0197] : secret message length

[0198] hash function Length of the value

[0199] is a fixed parameter. ).

[0200] To prevent a Trojan horse attack, a wavelength filter is used before the photons reach Alice. In other words, Alice can receive the photons based on the wavelength filter. In subsequent operations, the wavelengths of the photons prepared by Alice and Bob must be the same.

[0201] Each photon has 4 polarization states ( It can be randomly located in one of the four polarization states. In other words, a photon based on one of the four polarization states can be randomly selected.

[0202] Below, the bundle of photons traveling from Bob to Alice It is referred to as a batch.

[0203] ② Step 2: Security Inspection Phase

[0204] Alice After receiving the batch, Alice and Bob check the security.

[0205] Alice arbitrarily Half of the batch is selected to verify security. The selected photons at this time Referred to as a batch, the unselected photons It is referred to as a batch (i.e., ).

[0206] Alice Randomly process the qubits of the batch into one of the following 1) or 2).

[0207] 1) Reflection

[0208] 2) Measure using Zbasis and transmit again in the same state as Alice found (measure it with Zbasis and resend it in the same state she found).

[0209] Alice reveals the reflection position, the measurement position, and their values ​​to Bob. In other words, Alice Reveal to Bob the reflected photons from the batch and the photons measured using the Z basis.

[0210] Through this, Bob can check the errors of the reflection photons and the error of the measurement result.

[0211] If there are no errors (or very few), Bob determines that the channel is safe and instructs Alice to proceed to the next phase. Otherwise (if there are errors), Bob discards the protocol.

[0212] ③ Step 3: Message coding and retransmission step

[0213] Bob conveys the positions of the photons transmitted in the Z basis to Alice. Here, Photons identified as Z basis in the batch It is referred to as a batch.

[0214] The reason why the basis of the photons can be disclosed is as follows: the security of Alice's message transmission can be guaranteed through one-time pad encryption. The fact that safety is guaranteed in a batch means using the same channel This means that the batch is also safe. Therefore, even if the positions of photons with a specific basis (e.g., Z basis) are disclosed, there is no security issue.

[0215] The number of photons in the batch is m(secret message It must be greater than or equal to the length of ). Otherwise, Alice and Bob discard the protocol. This is because the batch cannot be smaller than the message Alice intends to send.

[0216] Alice Calculate.

[0217]

[0218] Here, is a one-way hash function.

[0219] Alice Each of the photons in the batch is a secret message It encodes according to ). Specifically, Alice is The quantum state of the i-th photon in the batch is processed as follows.

[0220] If =0, Alice leaves the quantum state of the i-th photon as is. In other words, Alice holds the quantum state of the i-th photon unchanged.

[0221] If =1, Alice flips the quantum state of the i-th photon. Since Alice is classical, to flip the quantum state of the Z basis, she uses the method of measuring a qubit and preparing it with the opposite value. In other words, Alice can change the corresponding quantum state to the opposite by measuring the quantum state of the i-th photon.

[0222] As mentioned above, Alice photons identified as the Z basis in the batch It is possible to encode a batch of photons. Message encoding applying these quantum states is equivalent to conventional one-time pad encryption.

[0223] Alice sends the encoded photons to Bob.

[0224] Bob measures the photons and compares the measurement results with the states he sent to the messages You can obtain.

[0225] if, In this case, Bob decides that the message has not been tampered with, and It is accepted that the message was sent by Alice. If not, Bob determines that the message was manipulated by someone other than Alice.

[0226] < Proposed Semiquantum secure direct communication without classical party's measurement protocol >

[0227] A method for performing SQSDC without measuring classical party according to an embodiment of the present specification will be specifically described below with reference to FIGS. 13 to 15.

[0228] The proposed SQSDC protocol proceeds as follows based on Step 1, Step 2, and Step 3.

[0229] FIG. 13 is a diagram illustrating Step 1 and Step 2 of SQSDC according to an embodiment of the present specification.

[0230] ① Step 1: Transmission Step

[0231] Bob is Prepare 'n' polarized single photons and transmit them to Alice. Here, n is based on Equation 3. Explanations that overlap with Step 1 described above regarding the conventional SQSDC are omitted. Here, the bundle of photons traveling from Bob to Alice It is referred to as a batch. Referring to Fig. 13, Bob has 6 photons ( Sends the batch to Alice.

[0232] ② Step 2: Security Inspection Phase

[0233] Alice After receiving the batch, Alice and Bob check the security.

[0234] (step 2-1) Alice is n photons are randomly selected from the batch of photons to verify security. The selected photons Referred to as a batch, the unselected photons It is referred to as a batch (i.e., Referring to Fig. 13, Alice uses 2 of the 6 photons ( Select batch.

[0235] (step 2-2) Alice has quantum states based on the Z basis One of them is randomly selected to generate n states. Alice has n states and It is generated as a single sequence based on the batch. At this time, the sequence is generated based on reordering. Here, the reordered qubit sequence It is referred to as a batch. Referring to FIG. 13, Alice has two states and two selected photons ( Based on the reordering of the batch, the sequence ( Creates a batch.

[0236] (step 2-3) Alice is Send the batch to Bob.

[0237] (step 2-4) Bob randomly selects either the Z basis or the X basis and based on it Measure each qubit (photon) of the batch.

[0238] (step 2-5) Alice reveals the reorder sequence to Bob. Alice tells Bob the above sequence ( Transmits order information indicating the order related to the creation of the batch.

[0239] Bob reveals the positions of the qubits generated by Alice, measured in the Z basis, and the results. Referring to Fig. 13, the positions of the photons measured in the Z basis are 5 and 7. For example, the position of the photon is batch and It can be defined based on the total photons in a batch. Among the 8 photons, the one measured in the Z basis The positions of the photons in the batch can be expressed as 5, 7. The measurement results of the photons measured in the corresponding Z basis are 1, 0.

[0240] Alice and Bob check the error rate, and if the error rate is higher than the threshold, they discard the protocol. If there are no errors (or very few errors) (e.g., 0%), Bob determines that the channel is safe and instructs Alice to proceed to the next phase.

[0241] FIG. 14 is a diagram illustrating Step 3 of the SQSDC according to an embodiment of the present specification.

[0242] ③ Step 3: Message coding and retransmission step

[0243] (step 3-1) Bob informs Alice of the positions of the photons transmitted in the Z basis. Referring to Fig. 14, Bob has 6 photons ( Information indicating the positions of photons transmitted in Z basis among batches (1 to 6) (e.g., 1, 4, 5) is transmitted to Alice.

[0244] (step 3-2) The photons (1, 4) identified as Z basis among the photons (1~4) of the batch It is referred to as a batch.

[0245] Even if the basis of the batch of photons is disclosed, there is no security issue. This is because the security of Alice's message transmission can be guaranteed through one-time pad encryption. The fact that safety is guaranteed in a batch means using the same channel This means that the batch is also safe. Therefore, even if the positions of photons with a specific basis (e.g., Z basis) are disclosed, there is no security issue.

[0246] (step 3-3) The number of photons in the batch is m(secret message It must be greater than or equal to the length of (01). Otherwise, Alice and Bob discard the protocol. Referring to FIG. 14, the number of photons (2) in batch B is equal to the length of message M (01).

[0247] (step 3-4) Alice is Creates.

[0248]

[0249] Here, is a one-way hash function.

[0250] Specifically, Alice batch and The hash value of By connecting Creates. The batch is generated as follows.

[0251] The i-th element of It is defined as. Alice is A single photon based on Prepare. The i-th element of the batch Defined as.

[0252] Alice cast Randomly decide whether to place it before or after (e.g. or Referring to Fig. 14, Alice has a message Photons based on ( , )second batch ( , Insert into ) sequence( , , , Generates ). The corresponding sequence It is referred to as a batch.

[0253] (step 3-5) Alice is generated based on batch Sends to Bob.

[0254] (step 3-6) Bob is Bob measures the photons. Bob groups the measured values ​​in pairs in order. Specifically, Bob groups m measured values ​​into pairs. The measured values ​​after the m pairs are h' sequences (i.e., hash values).

[0255] A sequence based on a group of measurements (m groups) can be expressed as shown in the following mathematical equation 6.

[0256]

[0257] Referring to FIG. 14, the sequence based on a group of measurements is : (0, 0), (1, 0) is.

[0258] (step 3-7) Bob is Since we know the batch information The estimated value of You can obtain.

[0259] If there are no errors , One of them and the remaining one Because of this, The i-th element of can be obtained based on the following mathematical formula 7.

[0260]

[0261] It can be expressed as shown in the following mathematical equation 8.

[0262]

[0263] Referring to Fig. 14, Bob i) second = Determine =0, and ii) cast = Determine =1 (i.e., = 0, 1).

[0264] if In this case, Bob decides that the message has not been tampered with, and It is accepted that the message was sent by Alice. Otherwise, Bob determines that the message was manipulated by someone other than Alice. The transmission and reception procedure based on the aforementioned actions is described below.

[0265] FIG. 15 illustrates a transmission and reception procedure according to an embodiment of the present specification.

[0266] Referring to Fig. 15, the transmission and reception procedure between Alice and Bob is performed based on a classical channel or a quantum channel. For convenience of explanation, it is described based on Alice.

[0267] In S1510, Alice receives a batch A from Bob. This step may be based on Step 1 described above.

[0268] In S1520, Alice sends S batch based on A batch to Bob. This step may be based on steps 2-1 through 2-4 described above.

[0269] In S1530, Alice sends order information to Bob. This step may be based on step 2-5.

[0270] In S1540, Alice receives matched basis information from Bob. This step may be based on step 2-5. Specifically, the matched basis information may include the positions of photons measured in the Z basis among the photons of the S batch and the results.

[0271] In S1550, Alice transmits the Quantum Bit Error Rate (QBER) to Bob. This step may be based on step 2-5. Specifically, the QBER may be determined based on the matched basis information. The QBER represents the error rate of photons measured by Bob in the Z basis among the photons of the S batch.

[0272] In S1560, Alice receives the Z basis position from Bob. This step may be based on step 3-1. Specifically, the Z basis position may represent the positions of photons transmitted in the Z basis among the photons of a batch A.

[0273] At S1570, Alice sends a message to Bob. This step may be based on steps 3-2 through 3-7. The message sent by Alice is It can be expressed by (Equation 5). The message received by Bob is It can be expressed as (Mathematical Equation 6).

[0274] In terms of implementation, the operations of the first device (Alice or Bob) / second device (Bob or Alice) according to the embodiments described above can be processed by the devices of FIGS. 1 to 5 described above (e.g., the processor (202a, 202b) of FIG. 2).

[0275] In addition, the operations of the first device (Alice or Bob) / second device (Bob or Alice) according to the above-described embodiment may be stored in memory (e.g., 204a, 204b of FIG. 2) in the form of instructions / programs (e.g., instructions, executable code) for driving at least one processor (e.g., processor (202a, 202b) of FIG. 2).

[0276] The embodiments described above will be explained in detail below with reference to FIGS. 16 and 17 in terms of the operation of the first device and the second device (e.g., 200a and 200b of FIG. 2). The methods described below are distinguished only for convenience of explanation, and it is understood that a part of one method may be substituted with a part of another method or combined with one another and applied.

[0277] The definitions of the first and second devices below are as follows. The first device may mean Alice or the sender. The second device may mean Bob or the receiver.

[0278] FIG. 16 is a flowchart illustrating a method according to one embodiment of the present specification.

[0279] Referring to FIG. 16, a method according to one embodiment of the present specification includes S1610 to S1660. S1610 to S1660 may be based on at least one of S1510 to S1570 of FIG. 15.

[0280] In S1610, the first device receives photons from the second device. For example, the photons may refer to the photons of batch A described above (see Step 1).

[0281] In S1620, the first device transmits a qubit sequence generated based on the photons to the second device. For example, the qubit sequence may be based on the S batch described above (e.g., 2n qubit sequence) (see steps 2-1 to 2-3).

[0282] In S1630, the first device receives measurement information based on the qubit sequence from the second device. The measurement information includes information related to qubits measured based on a Z basis among the qubits based on the qubit sequence. For example, the measurement information may be based on matched basis information described in FIG. 15 (see steps 2-4 to 2-5).

[0283] In S1640, the first device transmits information regarding the Quantum Bit Error Rate (QBER) determined based on the measurement information to the second device (step 2-5, see S1550 in FIG. 15).

[0284] In S1650, the first device receives basis information from the second device. The basis information represents the first photons among the photons based on the Z basis (step 3-1, see S1560 in FIG. 15).

[0285] More specifically, the first photons can be divided into i) first photons belonging to the S' batch among the photons of batch A and ii) first photons belonging to the T batch among the photons of batch A (i.e., ).

[0286] In other words, the first photons include i) first photons belonging to the photons selected for generating the qubit sequence (S' batch) among the photons and ii) first photons belonging to the remainder (T batch) excluding the selected photons among the photons (e.g., B batch).

[0287] In S1660, the first device transmits information related to the message to the second device. The information related to the message includes i) the first photons (e.g., First photons (e.g., m) determined based on the length of the message above among the batch) ) and ii) second photons based on the above message (e.g., It can be generated based on ).

[0288] According to one embodiment, the information related to the message is as described above. It may be based on (Equation 5) (see steps 3-2 to 3-7). Specifically, the information associated with the message may include i) the determined first photons and ii) a first sequence generated based on the second photons.

[0289] For each of the indices based on the length of the message in the first sequence (e.g., i=1,2..m), each first photon (e.g., ) and each second photon (e.g., ) can be arranged in a fixed order.

[0290] For example, the above-mentioned predetermined order is a first order in which each first photon is placed first (e.g., ) or a second order in which each second photon is placed first (e.g., It can be.

[0291] For example, the above information related to the above message (e.g., ) may include a second sequence associated with a hash function. The second sequence is the message (e.g., The above hash function based on ) (e.g., The first output value of ) (e.g.: It can be based on ).

[0292] At this time, the message may be estimated based on the information related to the message received by the second device. For example, the estimated message is as described above. It may be based on. As a specific example, each element of the estimated message above may be i) two values ​​based on the measurement of the information related to the message (e.g., , ) and ii) the first photons determined above (e.g., It can be determined based on the sum of one of ).

[0293] A second output value of the hash function based on the estimated message above (e.g., ) is the above first output value (e.g., Based on ) and other factors, the estimated message may be determined to be manipulated. Based on the second output value being the same as the first output value, the estimated message may be determined to have been transmitted by the first device.

[0294] According to one embodiment, the method may further include a step of transmitting order information. Specifically, the first device transmits order information related to the generation of the qubit sequence to the second device.

[0295] A sequence having a length of 2n can be generated based on n selected photons (e.g., S' batch) among the above photons and n states based on the Z basis. A qubit sequence can be generated based on a reorder of the generated sequence. The order information may indicate the order related to the reorder.

[0296] According to one embodiment, the basis information may be received based on the QBER being less than or equal to a threshold value. A protocol based on the photons may be discarded based on the QBER being greater than the threshold value.

[0297] According to one embodiment, the measurement information may include i) the position of each of the measured qubits in the qubit sequence and ii) a measurement value for each of the measured qubits.

[0298] The operation based on S1610 to S1660 described above can be implemented by the device of FIG. 2. For example, the first device (200a or 200b) can control one or more transceivers (206a or 206b) and / or one or more memories (204a or 204b) to perform an operation based on the operation based on S1610 to S1660.

[0299] FIG. 17 is a flowchart illustrating a method according to another embodiment of the present specification.

[0300] Referring to FIG. 17, a method according to another embodiment of the present specification includes S1710 to S1760. S1710 to S1760 correspond to S1610 to S1660 described in FIG. 16, so a redundant description is omitted.

[0301] In S1710, the second device transmits photons to the first device.

[0302] In S1720, the second device receives a qubit sequence generated from the first device based on the photons.

[0303] In S1730, the second device transmits measurement information based on the qubit sequence to the first device.

[0304] In S1740, the second device receives information regarding the Quantum Bit Error Rate (QBER) determined from the first device based on the measurement information.

[0305] In S1750, the second device transmits basis information to the first device.

[0306] In S1760, the second device receives information related to a message from the first device.

[0307] The operation based on S1710 to S1760 described above can be implemented by the device of FIG. 2. For example, the second device (200a or 200b) can control one or more transceivers (206a or 206b) and / or one or more memories (204a or 204b) to perform the operation based on S1710 to S1760.

[0308] Here, the wireless communication technology implemented in the wireless devices (200a, 200b) of this specification may include LTE, NR, and 6G, as well as Narrowband Internet of Things for low-power communication. For example, NB-IoT technology may be an example of LPWAN (Low Power Wide Area Network) technology and may be implemented according to standards such as LTE Cat NB1 and / or LTE Cat NB2, but is not limited to the names mentioned above. Additionally, or generally, the wireless communication technology implemented in the wireless devices (200a, 200b) of this specification may perform communication based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be referred to by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology may be implemented in at least one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-Bandwidth Limited), 5) LTE-MTC, 6) LTE Machine Type Communication, and / or 7) LTE M, and is not limited to the names mentioned above. Additionally or generally, wireless communication technology implemented in the wireless devices (200a, 200b) of this specification may include at least one of ZigBee, Bluetooth, and Low Power Wide Area Network (LPWAN) for low-power communication, and is not limited to the names mentioned above. As an example, ZigBee technology can create personal area networks (PANs) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and may be referred to by various names.

[0309] The embodiments described above are combinations of the components and features of this specification in a specific form. Each component or feature should be considered optional unless otherwise explicitly stated. Each component or feature may be implemented in a form not combined with other components or features. Additionally, it is possible to construct embodiments of this specification by combining some components and / or features. The order of operations described in the embodiments of this specification may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment. It is obvious that embodiments may be constructed by combining claims that do not have an explicit citation relationship in the claims, or that they may be included as new claims through amendments made after filing.

[0310] Embodiments according to the present specification may be implemented by various means, e.g., hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, an embodiment of the present invention may be implemented by one or more ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), processors, controllers, microcontrollers, microprocessors, etc.

[0311] In the case of implementation by firmware or software, an embodiment of the present specification may be implemented in the form of a module, procedure, function, etc., that performs the functions or operations described above. The software code may be stored in memory and executed by a processor. The memory may be located inside or outside the processor and may exchange data with the processor by various known means.

[0312] It is obvious to those skilled in the art that this specification may be embodied in other specific forms without departing from the essential features of this specification. Accordingly, the detailed description set forth above should not be interpreted restrictively in all respects but should be considered illustrative. The scope of this specification shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of this specification are included within the scope of this specification.

Claims

1. Regarding the method, A step of receiving photons from a second device; A step of transmitting a qubit sequence generated based on the photons to the second device; A step of receiving measurement information based on the qubit sequence from the second device, wherein the measurement information includes information related to qubits measured based on a Z basis among the qubits based on the qubit sequence; A step of transmitting information regarding the Quantum Bit Error Rate (QBER) determined based on the measurement information to the second device; The step of receiving basis information from the second device, wherein the basis information represents first photons based on the Z basis among the photons; and The method includes the step of transmitting information related to a message to the second device, wherein A method characterized by the information related to the above message being generated based on i) first photons determined based on the length of the message among the above first photons and ii) second photons based on the message.

2. In Paragraph 1, The information related to the above message includes i) the determined first photons and ii) a first sequence generated based on the second photons, and A method characterized in that, for each of the indices based on the length of the message in the first sequence, each first photon and each second photon are arranged in a predetermined order.

3. In Paragraph 2, A method characterized in that the above-mentioned predetermined order is a first order in which each first photon is placed first, or a second order in which each second photon is placed first.

4. In Paragraph 2, The information related to the above message includes a second sequence related to a hash function, and A method characterized in that the second sequence is based on the first output value of the hash function based on the message.

5. In Paragraph 4, The message is estimated based on the information related to the message received by the second device, and A method characterized in that each element of the estimated message is determined based on i) two values ​​based on the measurement of the information related to the message and ii) the sum of one of the determined first photons.

6. In Paragraph 5, A method characterized by determining that the estimated message is manipulated based on the fact that the second output value of the hash function based on the estimated message is different from the first output value.

7. In Paragraph 6, A method characterized by determining that the estimated message was transmitted by the first device based on the fact that the second output value is the same as the first output value.

8. In Paragraph 1, A method characterized by further including the step of transmitting order information related to the generation of the qubit sequence to the second device.

9. In Paragraph 8, A sequence having a length of 2n is generated based on n photons selected from the above photons and n states based on the Z basis, and The qubit sequence is generated based on the reordering of the above-generated sequence, and A method characterized by the above-mentioned order information indicating the order related to the above-mentioned reorder.

10. In Paragraph 1, A method characterized by receiving the above-mentioned base information based on the fact that the above-mentioned QBER is less than or equal to a threshold value.

11. In Paragraph 10, A method characterized by discarding a protocol based on the photons based on the fact that the above QBER is greater than the above threshold.

12. In Paragraph 1, A method characterized by the above measurement information including i) the position of each of the measured qubits in the above qubit sequence and ii) a measurement value for each of the above measured qubits.

13. In the first device, One or more transmitters / receivers; One or more processors; and It includes one or more memories connected to the above one or more processors and storing instructions, A first device characterized by the above instructions being set so that the one or more processors perform all steps of the method according to any one of claims 1 to 12, based on execution by the one or more processors.

14. In one or more non-transitory computer-readable media storing instructions, One or more non-transitory computer-readable media characterized by instructions executable by one or more processors, wherein the one or more processors are configured to perform all steps of the method according to any one of claims 1 to 12.

15. Regarding the method, A step of transmitting photons to a first device; A step of receiving a qubit sequence generated based on the photons from the first device; A step of transmitting measurement information based on the qubit sequence to the first device, wherein the measurement information includes information related to qubits measured based on a Z basis among the qubits based on the qubit sequence; A step of receiving information regarding the Quantum Bit Error Rate (QBER) determined based on the measurement information from the first device; A step of transmitting basis information to the first device, wherein the basis information represents first photons based on the Z basis among the photons; and The method includes the step of receiving information related to a message from the first device, A method characterized by the information related to the above message being generated based on i) first photons determined based on the length of the message among the above first photons and ii) second photons based on the message.

16. In the second device, One or more transmitters / receivers; One or more processors; and It includes one or more memories connected to the above one or more processors and storing instructions, A second device characterized by the above instructions being set so that the one or more processors perform all steps of the method according to claim 15, based on execution by the one or more processors.

17. In one or more non-transitory computer-readable media storing instructions, One or more non-transitory computer-readable media characterized by instructions executable by one or more processors, wherein the one or more processors are configured to perform all steps of the method according to claim 15.

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