KR20200068374A - Method for transmitting message in quantum key distribution system - Google Patents

Abstract

The present invention relates to a message transmission method performed in a quantum key distribution system including a first communication device and a second communication device. According to the present invention, the message transmission method comprises the steps of: (a) generating a shift key between the first communication device and the second communication device through a quantum key distribution protocol; (b) generating, by the first communication device, a block composed of a plurality of consecutive keys among shift keys stored in the first communication device according to a message to be transmitted to the second communication device, and transmitting the block to the second communication device; and (c) recovering, by the second communication device, the message by calculating the block with a shift key stored in the second communication device.

Description

Message transmission method in quantum key distribution system{METHOD FOR TRANSMITTING MESSAGE IN QUANTUM KEY DISTRIBUTION SYSTEM}

The present invention relates to a message communication technology in a quantum key distribution system, and after correcting an error value of a shift key by using a shift key generated through a quantum key distribution protocol between a receiving device and a transmitting device It relates to a message transmission method for directly transmitting a message from a transmitting device to a receiving device without processing.

In general, a shift key generated through a quantum key distribution protocol (eg, BB84 protocol) needs to be post-processed due to a quantum bit error rate (QBER). That is, since the generated shift key has an error value due to stability of the optical system, a detector error rate, and the like, a post-processing process for correcting an error value using an error correction algorithm used in existing optical communication such as Cascade, LDPC, Winnow, etc. This is going on. In addition, during the process of correcting such an error value, the security of the secret key may be compromised due to the information being exposed, so security can be improved through a security amplification method using a hash function. Will increase. However, the process of correcting the error value and amplifying the security after generating the shift key through the quantum key distribution protocol is performed through the classic communication, so there is a possibility that it may be threatened with safety, and many keys are discarded in the process. There is a problem of reduced efficiency.

Korean Patent Publication No. 10-2014-0054647

An object of the present invention is to provide a message transmission method for transmitting a message directly from a shift key generated through a quantum key distribution protocol.

A first aspect of the present invention for achieving the above object is a message transmission method performed in a quantum key distribution system including a first communication device and a second communication device, (a) the first communication device and the second Generating a shift key through a quantum key distribution protocol between communication devices; (b) The first communication device generates a block composed of a plurality of consecutive keys among shift keys stored in the first communication device according to a message to be transmitted to the second communication device and transmits it to the second communication device. To do; And (c) the second communication device comprises recovering the message by calculating the block with a shift key stored in the second communication device.

Preferably, the step (b) includes (b-1) determining a message to be transmitted to the second communication device, wherein the message corresponds to 0 or 1; (b-2) calculating a shift stored in the first communication device with the determined message, wherein the operation corresponds to an XOR operation; And (b-3) determining a block corresponding to the message from the calculated shift key.

Preferably, the step (b-3) comprises: determining the size of the block according to the quantum bit error rate of the shift key stored in the first communication device; And determining a block including more values corresponding to the message, among blocks that can be generated according to the determined size of the block from the calculated shift key.

Preferably, step (c) comprises: (c-1) receiving the block; (c-2) calculating a shift key corresponding to the block among the blocks and shift keys stored in the second communication device, wherein the operation corresponds to an XOR operation; And (c-3) restoring the value included in the calculated shift key to the message.

A second aspect of the present invention for achieving the above object is a quantum key distribution system including a first communication device and a second communication device, wherein the first communication device, the second communication device and the quantum key distribution protocol The first shift key generation unit to generate a shift key by performing a, and generates a block composed of a plurality of consecutive keys among the shift keys stored in the first communication device according to a message to be transmitted to the second communication device. And a first message communication unit for transmitting to a second communication device, the second communication device comprising: a second shift key generation unit that performs a quantum key distribution protocol with the first communication device to generate a shift key, and the second communication device. And a second message communication unit that restores the message by calculating the block received from one communication device with a shift key stored in the second communication device.

According to the present invention as described above, since the message is transmitted directly from the distributed quantum key, it is possible to minimize the situation in which classical communication must be used, and also the quantum bit error rate after distribution of the quantum key ( It is possible to prevent discarded values for QBER) and to perform quantum bit error rate (QBER) checking at the same time as message transmission.

1 is a block diagram showing a quantum key distribution system according to a preferred embodiment of the present invention.
FIG. 2 is a flowchart illustrating a message transmission method performed in the quantum key distribution system of FIG. 1.
3 and 4 are exemplary views for explaining a message transmission method.

Hereinafter, advantages and features of the present invention, and a method of achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments allow the disclosure of the present invention to be complete, and the ordinary knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification. “And/or” includes each and every combination of one or more of the items mentioned.

Although the first, second, etc. are used to describe various elements, components and/or sections, it goes without saying that these elements, components and/or sections are not limited by these terms. These terms are only used to distinguish one element, component or section from another element, component or section. Therefore, it goes without saying that the first element, first component or first section mentioned below may be a second element, second component or second section within the technical spirit of the present invention.

In addition, in each step, an identification code (for example, a, b, c, etc.) is used for convenience of description, and the identification code does not describe the order of each step, and each step is clearly specified in context. Unless the order is specified, it may occur differently from the order specified. That is, each step may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

The terminology used herein is for describing the embodiments and is not intended to limit the present invention. In the present specification, the singular form also includes the plural form unless otherwise specified in the phrase. As used herein, “comprises” and/or “comprising” refers to the components, steps, operations and/or elements mentioned above, the presence of one or more other components, steps, operations and/or elements. Or do not exclude additions.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used as meanings commonly understood by those skilled in the art to which the present invention pertains. In addition, terms defined in the commonly used dictionary are not ideally or excessively interpreted unless specifically defined.

In addition, in describing embodiments of the present invention, when it is determined that a detailed description of known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. In addition, terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to a user's or operator's intention or practice. Therefore, the definition should be made based on the contents throughout this specification.

1 is a block diagram showing a quantum key distribution system according to a preferred embodiment of the present invention.

Referring to FIG. 1, the quantum key distribution system includes a first communication device 100 as a transmitting device (so-called Alice) and a second communication device 200 as a receiving device (so-called Bob). Preferably, the first communication device 100 and the second communication device 200 may be connected through a quantum channel (QC) and a classic channel, and a signal is transmitted and received through the quantum channel, and data through the classic channel Can be transmitted and received.

The first communication device 100 includes a first shift key generation unit 110 and a first message communication unit 120, and the second communication device 200 includes a second shift key generation unit 210 and a second message. It includes a communication unit 220.

Preferably, the first shift key generation unit 110 and the second shift key generation unit 210 may be connected to a quantum channel to perform a quantum key distribution protocol. The first shift key generation unit 110 and the second shift key generation unit 210 using the quantum key distribution protocol (for example, BB84 protocol) process of distributing the quantum key and a specific configuration for performing the same are as follows It can be easily implemented by those skilled in the art to which the invention pertains and its implementation method can be variously modified, and thus detailed description is omitted.

Preferably, the first message communication unit 120 and the second message communication unit 220 are connected to a classic channel to perform message transmission and reception. The first message communication unit 120 and the second message communication unit 220 are generated after a shift key is generated through the first shift key generation unit 110 and the second shift key generation unit 210. The process of transmitting and receiving a message using a shift key, and a process of transmitting and receiving a message using a shift key will be described below in more detail.

FIG. 2 is a flowchart illustrating a message transmission method performed in the quantum key distribution system of FIG. 1.

Referring to FIG. 2, a quantum key distribution protocol is performed by the first shift key generator 110 and the second shift key generator 210 to generate a shift key (step S210), The communication device 100 and the second communication device 200 each store a shift key. Here, the method in which the shift key is generated by the quantum key distribution protocol is not described in detail as it can be easily implemented by those skilled in the art.

When a shift key is generated by a quantum key distribution protocol, the first message communication unit 120 of the first communication device 100 may have a plurality of consecutive shift keys stored according to a message to be transmitted to the second communication device 200. A block composed of keys is generated and transmitted to the second communication device 200 (step S220).

More specifically, the first message communication unit 120 determines a message to be transmitted to the second communication device 200. Here, the message corresponds to “0” or “1”. Then, the first message communication unit 120 XORs the shift key with the determined message. For example, referring to FIG. 3, when the shift key {0101011100} is stored in the first communication device 100 and a message corresponding to “0” is to be transmitted to the second communication device 200, the first The message communication unit 110 may calculate an operation result by XORing each key constituting the shift key to “0” corresponding to the message. The XOR operation compares each digit of two values and calculates 0 if the values are the same and 1 if the values are different. In FIG. 3, the value corresponding to 0 of the shift key is the same as the message “0”, so the result is calculated as 0. , Since the value corresponding to 1 among the shift keys is different from the message “0”, the result is calculated as 1.

Preferably, when the shift key is XORed into a message, the first message communication unit 120 determines a block corresponding to the message from the calculated shift key. More specifically, the first message communication unit 120 determines the size of the block according to the quantum bit error rate (QBER) of the shift key, and among the blocks that can be generated from the shift key calculated according to the determined size of the block, the message One block containing more corresponding values is determined. For example, in relation to a method for determining the size of a block, a block size may be collectively determined after QBER inspection in a portion after initial shift key generation. As another example, if a block size that is presumed to have some error rate is set in advance and then used, then it is necessary to reset the size appropriately according to the variation of QBER in the second communication device 200 in the middle. 1 The communication device 100 can be determined to adjust the block size by communicating to adjust the block size.

Meanwhile, in the example illustrated in FIG. 3, when the block is determined, it is described as an example in which the block starts from the first key of the shift key. However, when determining a block, the block does not necessarily start from the first key of the shift key. Information blocks that should be used from a few blocks between the first communication device 100 and the second communication device 200 may be shared with each other through a classic channel. Preferably, it is possible to use from the first block, without having to additionally communicate information that should be used from the first block. For reference, the shift key may be discarded after use. Therefore, when it is used as a block corresponding to the message, the corresponding shift key is discarded, and the next message is preferably used from the next shift key used.

Preferably, when a block corresponding to a message to be transmitted from the first message communication unit 120 of the first communication device 100 to the second communication device is generated, the first message communication unit 120 blocks the block through the classic channel. It transmits to the second message communication unit 220 of the second communication device 200.

The second message communication unit 220 of the second communication device 200 restores the message by calculating the block received from the first message communication unit 120 with the stored shift key (step S230). More specifically, when receiving the block, the second message communication unit 220 performs XOR operation on the shift key corresponding to the block among the stored shift keys. For example, referring to FIG. 4, a shift key corresponding to {0111011100} is stored in the second communication device 200, and the second message communication unit 220 is a key {011 corresponding to a block in the stored shift key } {OR} can be XORed with the block {010} to calculate {001}. Then, the second message communication unit 220 restores a value that contains more of 0 and 1 included in the operation result as a message. For example, as 0 is 2 and 1 is 1 in the result of the operation {001}, and more 0 is included, the second message communication unit 220 may restore “0” to a message.

In one embodiment, the second communication device 200 may check QBER in data transmission. More specifically, the second communication device 200 can know the QBER when the block comes and performs XOR operation with the shift key that it has. There is no error rate if all bits have one value in the result of XOR operation. If a value with a different value such as 1 out of 3 or 1 out of 5 appears, the second communication device (200) ) Can know the QBER. For example, if 5 blocks are grouped and 1 bit in one of the 20 blocks has an error, it means that QBER is 1%.

On the other hand, the message transmission method according to an embodiment of the present invention may also be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored.

For example, the computer-readable recording medium includes ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, removable storage device, and non-volatile memory (Flash Memory). , Optical data storage, and the like.

Although the preferred embodiment of the message transmission method according to the present invention has been described above, the present invention is not limited to this, and it is possible to carry out various modifications within the scope of the claims and detailed description of the invention and the accompanying drawings. This also belongs to the present invention.

100: first communication device
110: first shift key generation unit
120: first message communication unit
200: second communication device
210: second shift key generation unit
220: message communication unit

Claims (5)

A method for transmitting a message performed in a quantum key distribution system including a first communication device and a second communication device,
(a) generating a shift key through a quantum key distribution protocol between the first communication device and the second communication device;
(b) The first communication device generates a block composed of a plurality of consecutive keys among shift keys stored in the first communication device according to a message to be transmitted to the second communication device, and transmits the block to the second communication device. To do; And
(c) the second communication device comprising the step of recovering the message by calculating the block with a shift key stored in the second communication device.
The method of claim 1, wherein the step (b),
(b-1) determining a message to be transmitted to the second communication device, wherein the message corresponds to 0 or 1;
(b-2) calculating a shift key stored in the first communication device with the determined message, wherein the operation corresponds to an XOR operation; And
(b-3) determining a block corresponding to the message from the calculated shift key.
The method of claim 2, wherein the step (b-3),
Determining the size of the block according to the quantum bit error rate of the shift key stored in the first communication device; And
And determining a block containing more values corresponding to the message, among blocks that can be generated according to the determined size of the block from the calculated shift key.
The method of claim 1, wherein step (c),
(c-1) receiving the block;
(c-2) calculating a shift key corresponding to the block among the blocks and shift keys stored in the second communication device, wherein the operation corresponds to an XOR operation; And
and (c-3) restoring the value included in the calculated shift key to the message.
In the quantum key distribution system comprising a first communication device and a second communication device,
The first communication device may include a first shift key generation unit generating a shift key by performing a quantum key distribution protocol with the second communication device, and the first communication device according to a message to be transmitted to the second communication device. It includes a first message communication unit for generating a block consisting of a plurality of consecutive keys of the shift key stored in the transmission to the second communication device,
The second communication device may include a second shift key generation unit that performs a quantum key distribution protocol with the first communication device to generate a shift key, and the block received from the first communication device to the second communication device. A quantum key distribution system including a second message communication unit to restore the message by operating with the stored shift key.

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