KR20170125659A - Method of distributing key for multi-party in quantum communication, method of performing quantum communication using the same and quantum communication system performing the same - Google Patents

Abstract

In a multi-party key distribution method in quantum communication, a plurality of base groups consisting of a combination of first and second bases are generated. A plurality of groups of qubits including a plurality of qubits are generated based on the plurality of base groups, and transmitted to a server. Based on first and second gates, a plurality of return qubit groups are generated by changing or maintaining each of the plurality of qubits included in the plurality of qubit groups, and transmitted to a plurality of user terminals. A plurality of key bits for generating a security key are obtained by comparing the plurality of qubit groups with the plurality of return qubit groups. The plurality of user terminals can efficiently share a key.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-party key distribution method, a quantum communication method using the same, and a quantum communication system for performing the same. 2. Description of the Related Art [0002]

The present invention relates to a communication system, and more particularly, to a method of distributing a key in a quantum communication, a quantum communication method using the multi-way key distribution method, a quantum communication method performing the multi- ≪ / RTI >

The quantum key distribution (QKD) protocol devised by C. H. Bennett and G. Brassard in 1984 can be called the BB84 protocol. There has been tremendous progress in the field of quantum cryptography since the BB84 protocol described above has been known. The key point of the quantum key distribution protocol is that two remote users create and share a secret key for encrypted communication over an open communication channel and at the same time ensure unconditional security of the shared secret key.

In general, the quantum key distribution protocol as described above is studied based on a case where two users share a key, but research on a case where a plurality of users share a key is also needed.

It is an object of the present invention to provide a method of distributing a key in a quantum communication in which a plurality of user terminals can efficiently share a key.

Another object of the present invention is to provide a quantum communication method using the above multi-party key distribution method.

It is still another object of the present invention to provide a quantum communication system for performing the above-mentioned multi-party key distribution method and / or the above-mentioned quantum communication method.

In order to achieve the above object, in a multi-party key distribution method in quantum communication according to embodiments of the present invention, a plurality of user terminals are divided into a plurality of base groups Lt; / RTI > The plurality of user terminals generates a plurality of groups of qubits each including a plurality of qubits based on the plurality of base groups and transmits them to the server. Wherein the server modifies or maintains each of the plurality of qubits contained in the plurality of qubits groups based on a first gate and a second gate to generate a plurality of return queue bit groups, And transmits the return queue bit groups to the plurality of user terminals. The plurality of user terminals compares the plurality of qubits groups and the plurality of return queue bit groups to obtain a plurality of key bits for generating a secret key.

In one embodiment, a first one of the plurality of user terminals generates a first base group comprising a combination of the first base and the second base, and generates a first base group based on the first base group, And generating and transmitting to the server a first group of qubits containing N (N is a natural number of 2 or more) qubits, comparing the first group of qubits with the group of first qubits sent from the server, And obtain the plurality of key bits.

In one embodiment, the server applies one of the first gate and the second gate to each of the first through the N-th queue bits so that the first through Nth queue bits included in the first return queue bit group Return cue bits, and determine the value of the plurality of key bits based on the application order of the first gate and the second gate.

In one embodiment, the server, when it is desired to set a first key bit of the plurality of key bits to a first bit value, applies the first gate to the first queue bit, Bit to a second bit value that is different from the first bit value, applying the second gate to the first qubit to generate the first return qubit .

In one embodiment, when the first qubit is generated based on the first basis, the first return qubit generated by applying the first gate to the first qubit and the first queue bit They can have different values. Wherein when the first qubit is generated based on the second basis, the first return qubit generated by applying the first gate to the first qubit and the first qubit have the same value have.

In one embodiment, when the first qubit is generated based on the first basis, the first return qubit generated by applying the second gate to the first qubit and the first queue bit Can have the same value. Wherein when the first qubit is generated based on the second basis, the first return qubit generated by applying the second gate to the first qubit and the first qubit have different values .

In one embodiment, the first basis may be a computational basis to represent spin down or spin up of electrons on a vertical axis. The second basis may be a Hadamard basis for indicating the spin-down or the spin-up of the electron on a horizontal axis.

In one embodiment, the first gate comprises a Pauligi X gate (not shown) operating as a negative gate (NOT gate) for changing the value of the first qubit when the first qubit is generated based on the computational basis (Pauli X gate). The second gate may be a Pauli Z gate (Pauli Z gate) operating as the undefined gate for changing the value of the first qubit if the first qubit is generated based on the Hadamard basis have.

In one embodiment, the first bit value may be one and the second bit value may be zero.

In one embodiment, both the plurality of user terminals and the server may share the same plurality of key bits.

To achieve the other object, in the quantum communication method according to the embodiments of the present invention, a plurality of user terminals generate a plurality of base groups consisting of a combination of a first base and a second base. The plurality of user terminals generates a plurality of groups of qubits each including a plurality of qubits based on the plurality of base groups and transmits them to the server. Wherein the server modifies or maintains each of the plurality of qubits contained in the plurality of qubits groups based on a first gate and a second gate to generate a plurality of return queue bit groups, And transmits the return queue bit groups to the plurality of user terminals. The plurality of user terminals compare the plurality of qubits groups and the plurality of return qubit groups to obtain a plurality of key bits. The server and the plurality of user terminals perform information reconciliation and privacy amplification on the plurality of key bits to share a secret key. The server and the plurality of user terminals encrypt and exchange data based on the security key.

In one embodiment, the plurality of qubits groups and the plurality of return queue bit groups may be transmitted on a quantum channel between the server and the plurality of user terminals. The information coordination and the privacy amplification may be performed through a public channel between the server and the plurality of user terminals.

In one embodiment, the number of bits of the secret key may be less than the number of the plurality of key bits.

In one embodiment, the data may be encrypted by a one-time pad scheme using the security key.

According to another aspect of the present invention, there is provided a quantum communication system including a plurality of user terminals and a server. The plurality of user terminals generating a plurality of base groups consisting of a combination of a first basis and a second basis and generating a plurality of base groups each comprising a plurality of qubits based on the plurality of base groups And generates qubits groups. Wherein the server is configured to receive the plurality of queue bits and to change or maintain each of the plurality of queue bits included in the plurality of queue bit groups based on a first gate and a second gate, Bit groups, and transmits the plurality of return queue bit groups to the plurality of user terminals. The plurality of user terminals compares the plurality of qubits groups and the plurality of return queue bit groups to obtain a plurality of key bits for generating a secret key.

In one embodiment, a first one of the plurality of user terminals generates a first base group comprising a combination of the first base and the second base, and generates a first base group based on the first base group, Generating a first group of qubits containing N (N is a natural number equal to or greater than 2) qubits and transmitting the groups to the server, comparing the first group of qubits with the group of first qubits sent from the server, And obtain the plurality of key bits. Wherein the server applies one of the first gate and the second gate to each of the first through the N-th queue bits to generate first through N-th return queue bits included in the first return queue bit group And determine the value of the plurality of key bits based on the application order of the first gate and the second gate.

In one embodiment, the server, when it is desired to set a first key bit of the plurality of key bits to a first bit value, applies the first gate to the first queue bit, Bit to a second bit value that is different from the first bit value, applying the second gate to the first qubit to generate the first return qubit .

In one embodiment, when the first qubit is generated based on the first basis, the first return qubit generated by applying the first gate to the first qubit and the first queue bit They can have different values. Wherein when the first qubit is generated based on the second basis, the first return qubit generated by applying the first gate to the first qubit and the first qubit have the same value have.

In one embodiment, when the first qubit is generated based on the first basis, the first return qubit generated by applying the second gate to the first qubit and the first queue bit Can have the same value. Wherein when the first qubit is generated based on the second basis, the first return qubit generated by applying the second gate to the first qubit and the first qubit have different values .

In one embodiment, the server and the plurality of user terminals may share the security key by performing information reconciliation and privacy amplification on the plurality of key bits. The server and the plurality of user terminals may encrypt and exchange data based on the security key.

In the multi-party key exchange method and the quantum communication method in the quantum communication according to the above-described embodiments of the present invention, the user terminals can share the key bits through communication with the server. At this time, the server does not directly generate the qubits, but rather selectively applies the first and second gates to the qubits generated at the user terminals and then returns the qubits to the user terminals, Information to the user terminals. Thus, the load of the server for key bit transmission can be reduced, and a plurality of user terminals can efficiently share the same key bits. Further, the performance of the quantum communication system performing the multi-party key exchange method and / or the quantum communication method in the quantum communication can be improved.

1 is a block diagram illustrating a quantum communication system in accordance with embodiments of the present invention.
2 is a flow chart illustrating a method for distributing a multi-party key in quantum communication according to embodiments of the present invention.
3 is a block diagram illustrating an example of a server and a first user terminal included in the quantum communication system of FIG.
4, 5A, 5B, 6 and 7 are tables for explaining a method of distributing a key in a quantum communication according to embodiments of the present invention.
8 is a flowchart illustrating a quantum communication method according to embodiments of the present invention.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

On the other hand, if an embodiment is otherwise feasible, the functions or operations specified in a particular block may occur differently from the order specified in the flowchart. For example, two consecutive blocks may actually be performed at substantially the same time, and depending on the associated function or operation, the blocks may be performed backwards.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a block diagram illustrating a quantum communication system in accordance with embodiments of the present invention.

Referring to FIG. 1, a quantum communication system 10 includes a server 100 and a plurality of user terminals 200, 300, 400, and 500.

The quantum communication system 10 is a communication system implemented using quantum mechanics and can transmit information based on the spin of electrons.

In the quantum communication system 10 according to the embodiments of the present invention, the user terminals 200, 300, 400, and 500 share the same key bits through communication with the server 100. The server 100 determines the key bits, and the user terminals 200, 300, 400, and 500 obtain the determined key bits. At this time, the user terminals 200, 300, 400, and 500 generate qubits, and the server 100 generates the qubits generated by the user terminals 200, 300, 400, And transmits information related to the key bits to the user terminals (200, 300, 400, 500) based on the qubits.

Each of the user terminals 200, 300, 400, and 500 and the server 100 may be connected through two channels. One of the two channels may be a quantum channel or a secure channel for transmitting the qubits and the other of the two channels may be a public channel for transmitting common data bits, a public channel or a classical channel. In Fig. 1, the quantum channel is shown by a solid arrow's double arrow, and the open channel is indicated by a dotted double arrow.

Two adjacent ones of the user terminals 200, 300, 400, and 500 may be connected through one channel. The one channel may be the open channel or the classical channel.

1, the quantum communication system 10 includes four user terminals 200, 300, 400, and 500. However, the quantum communication system 10 may include any M (M is a natural number) Lt; RTI ID = 0.0 > user terminals. ≪ / RTI >

2 is a flow chart illustrating a method for distributing a multi-party key in quantum communication according to embodiments of the present invention.

Referring to FIGS. 1 and 2, in a method of distributing a key in a quantum communication according to embodiments of the present invention, a plurality of user terminals 200, 300, 400, and 500 generate a plurality of basis groups (Step S100). Each of the plurality of base groups comprises a first basis and a combination of the first base and a second base different from the first base. As described below with reference to FIG. 4, each of the first and second bases may be used to generate or discriminate a qubit.

The user terminals 200, 300, 400, and 500 generate a plurality of groups of qubits based on the plurality of base groups and transmit them to the server 100 (step S200). Each of the plurality of qubit groups may include a plurality of qubit bits. As described below with reference to FIG. 4, the cuboid may represent a bit used in quantum communication, and may be generated based on one of the first and second bases and may correspond to one of "0" Value. ≪ / RTI >

The server 100 may change or maintain each of the plurality of qubits contained in the plurality of qubits groups based on a first gate and a second gate different from the first gate, And transmits the plurality of return queue bit groups to the user terminals 200, 300, 400, and 500 (step S300).

In one embodiment, the server 100 applies one of the first and second gates to each of the plurality of qubits contained in each qubits group, and generates a plurality of returns Can generate each of the qubits. The number of qubits in one qubits group may be substantially equal to the number of return qubits in a group of return qubits. One return queue bit in one queue bit group and one return queue bit group in the corresponding one of the queue bit groups are classified into a kind of base used at the time of generation of the qubits and a kind of the gate applied at the time of generation of the return qubit , They may have the same value or may have different values.

In one embodiment, the server 100 may determine the value of the plurality of key bits based on the application order of the first and second gates. This will be described later with reference to Figs. 6 and 7.

The user terminals 200, 300, 400, and 500 compare the plurality of the qubit groups and the plurality of return queue bit groups to obtain the plurality of key bits (step S400). As described below with reference to Fig. 8, the plurality of key bits may be used to generate a security key for performing secure communication in the quantum communication system 10. [

The plurality of qubit groups from which the user terminals 200, 300, 400, 500 occur may be different from each other, but the server 100 may be configured to receive the first and second qubit groups in the same order for all of the plurality of qubit groups. And applying the second gates to generate the plurality of return queue groups. Thus, both the plurality of user terminals 200, 300, 400, and 500 and the server 100 may share substantially the same plurality of key bits.

Although not shown in FIG. 2, as described later with reference to FIG. 8, after step S400, the server 100 and the user terminals 200, 300, 400, and 500 may adjust information about the plurality of key bits information reconciliation and privacy amplification, thereby sharing the security key. After the multi-party key distribution operation as described above, data can be encrypted and exchanged in the quantum communication system 10 based on the security key.

In the multi-party key distribution method in the quantum communication according to the embodiments of the present invention, the user terminals 200, 300, 400, and 500 may share the key bits through communication with the server 100. At this time, the server 100 does not directly generate the qubits, but selectively applies the first and second gates to the qubits generated in the user terminals 200, 300, 400, and 500, To the user terminals 200, 300, 400, 500 by transmitting the information related to the key bits to the user terminals 200, 300, 400, Thus, the load of the server 100 can be reduced, and the user terminals 200, 300, 400, and 500 can efficiently share the same key bits.

The operation of the quantum communication system 10 according to the embodiments of the present invention (for example, the first user terminal 200 and the second user terminal 200) will now be described based on the server 100 and one user terminal Multi-party key distribution operation) will be described in more detail.

3 is a block diagram illustrating an example of a server and a first user terminal included in the quantum communication system of FIG. 4, 5A, 5B, 6 and 7 are tables for explaining a method of distributing a key in a quantum communication according to embodiments of the present invention.

3 and 6, the server 100 may include a transmitting / receiving unit 110, a random number generating unit 120, and a return qubit generating unit 130. The first user terminal 200 includes a random number generator 210, a base determiner 220, a data provider 230, a qubit generator 240, a transceiver 250 and a key generator 260. . ≪ / RTI > The channels 202 and 204 may be connected between the server 100 and the first user terminal 200 to provide an information delivery path.

The random number generator 210 may generate the first random number RN1. For example, the first random number RN1 may be any binary number of N (N is a natural number) bits. The random number generator 210 may include any random number generator for generating the first random number RN1 and may generate the first random number RN1 manually based on the user set signal It is possible.

The base decision unit 220 can generate the first base group BG1. For example, the base determining unit 220 may convert each bit of the first random number RN1 to one of the first and second bases to generate the first base group BG1. For example, the first random number RN1 may include a first bit value (e.g., "1") of K (K is an integer of 0 to N) Bit binary value consisting of a combination of 2-bit values (e.g., "0"). In this case, the base determining unit 220 may convert the first bit value of the first random number RN1 to the first base and the second bit value of the first random number RN1 to the second base To generate a first base group BG1 consisting of a combination of N first and second bases.

4, the first base may be a computational basis for representing spin down or spin up of electrons on a vertical axis, May be a Hadamard basis for indicating the spin down or spin up of the electrons on a horizontal axis. The calculation basis may be denoted by "+ ", and the Hadamard basis may be denoted by" X ".

In the calculation base, an electron having the spin down state can be represented by a qubit (| 0>), and an electron having the spin up state can be represented by a qubit (| 1>). In the Hadamard base, an electron having the spin down state can be represented by a qubit (| +>), and an electron having the spin up state can be represented by a qubit (| ->).

In one embodiment, a qubit (| 0>) of the calculation base may correspond to a "0" of a binary bit and a qubit (| 1>) of the calculation base corresponds to a "1" can do. Similarly, a quadrature (| + >) of the Hadamard basis may correspond to a "0" of the binary bit, ≪ / RTI > In another embodiment, the value of the binary bit ("0" or "1") represented by each of the qubits (| 0>, | 1>, | +>, |

3 and 6, the generation operation of the first base group BG1 of the first user terminal 200 can be described based on the case where N is 10. [ For example, the random number generator 210 may generate a 10-bit first random number RN1 of "1101001001 ". The base decision unit 220 can generate the first base group BG1 of "++ x + xx + xx +" based on the first random number RN1 of "1101001001 ".

The data providing unit 230 may generate the first data DAT1. For example, similar to the first random number RN1, the first data DAT1 may be any binary data of N bits. Similar to the random number generator 210, the data provider 230 may include any random number generator or may generate the first data DAT1 based on the user setup signal. Although not shown, the data providing unit 230 may generate data to be encrypted and exchanged in the quantum communication system 10 after the key distribution operation.

The qubit generating unit 240 may generate the first qubit group QG1 based on the first base group BG1. For example, the qubit generating unit 240 may generate the first qubit group QG1 by encoding each bit of the first data DAT1 based on the basis of the first base group BG1, And an encoding unit for performing the encoding operation. For example, in a case where the first data DAT1 is N-bit binary data and the first base group BG1 is made up of N combinations of the first and second bases, the first qubit group QG1 is And may be data including first to N-th queue bits.

The generation operation of the first qubit group QG1 of the first user terminal 200 can be described based on the case where N is 10, as shown in Fig. For example, the data providing unit 230 may generate 10-bit first data DAT1 of "0100101011 ". The qubit generating unit 240 encodes the first data DAT1 of "0100101011" based on the first base group BG1 of "++ × + ×× + ×× +" and outputs the first qubit group QG1 ). The first qubit group QG1 includes a first qubit (| 0), a second qubit (| 1), a third qubit (| +>), a fourth qubit The first qubit (| +>), the sixth qubit (| +>), the seventh qubit (| 10 qubits (| 1 >).

The transceiver unit 250 may transmit the first qubit group QG1 to the server 100 and the transceiver unit 110 may receive the first qubit group QG1 from the first user terminal 200 have.

The random number generator 120 may generate a random number RN. For example, similar to the first random number RN1, the random number RN may be any binary number of N bits. Similar to the random number generator 210, the random number generator 120 may include any random number generator or may generate a random number (RN) based on the user set signal. For example, the random number RN may be substantially the same as a plurality of key bits KB1 obtained by the first user terminal 200. [

The return qubit generating unit 130 changes or maintains each of the first to Nth qubits included in the first qubit group QG1 on the basis of the first and second gates, Bit group RQG1. For example, the return qubit generating unit 130 applies one of the first and second gates to each of the first to N-th queue bits based on the random number RN, Bit group RQG1. For example, similarly to the first queue bit group QG1, the first return queue bit group RQG1 may be data including first through Nth return queue bits, Applies one of the first and second gates to the first qubits of the first qubit group QG1 based on the first bit of the random number RN to generate a first return queue bit group RQG1 Lt; RTI ID = 0.0 > of the < / RTI > The return qubit generating unit 130 may include the first and second gates.

Referring to FIG. 5A, the first gate may represent a Pauli X gate. Wherein the Pauligi X gate is configured to change the first qubit if the first qubit is one of the qubits generated based on the calculation basis (e.g., | 0>, | 1>) Lt; RTI ID = 0.0 > NOT gate < / RTI > For example, applying the Pauligi X gate to the qubits (| 0>) can be changed to a qubit (| 1>) and applying the Pauligi X gate to the qubits (| 1> | 0>). Wherein the Pauligi X gate is configured to change the first qubit if the first qubit is one of the qubits generated based on the Hadamard basis (e.g., | +>, | ->) It can be maintained without. For example, if the Pauligi X gate is applied to a qubit (| +>), a qubit (| +>) can be maintained and if the Pauligi gate is applied to a qubit (| | ->) can be maintained. The Pauligi X gate can be defined as: " (1) "

[Equation 1]

Referring to FIG. 5B, the second gate may represent a Pauli Z gate. The Pauli Z gate can operate in opposition to the Pauli X gate. The Pauligi Z gate may operate as the undefined gate for changing the first qubit if the first qubit is generated based on the Hadamard basis. For example, applying the Pauligi Z gate to a qubit (| +>) can be changed to a qubit (| ->), and applying the Pauligi Z gate to a qubit (| | + ≫). The Pauligi Z gate may maintain the first qubit bit unchanged if the first qubit is generated based on the calculation base. For example, applying the Pauligi Z gate to a qubit (| 0>) can maintain a qubit (| 0>) and applying the Pauligi Z gate to a qubit (| 1> | 1 >) can be maintained. The Pauligi gate can be defined as: " (2) "

&Quot; (2) "

Referring again to FIGS. 3 and 6, when it is desired to set the first key bit included in the plurality of key bits KB1 to the first bit value (e.g., "1"), Unit 130 may apply the first gate to the first qubits to generate the first return qubits. When the first key bit is set to the second bit value (e.g., "0"), the return qubit generating unit 130 applies the second gate to the first qubit, A first return qubit may be generated.

In one embodiment, the return qubit generating unit 130 may indicate the application order of the first and second gates based on the random number RN. For example, the random number RN may be different from the first bit value (e.g., "1") of L (L is an integer of 0 to N) For example, "0"). The return qubit generating unit 130 converts the first bit value of the random number RN into X (i.e., a value for applying the first gate), and outputs the second bit value of the random number RN as (I.e., a value for applying the second gate) to generate the application order (SO) of the first and second gates, which is a combination of N and the X and Z.

The generation operation of the first return queue bit group RQG1 of the server 100 can be described based on the case where N is 10, as shown in Fig. For example, the random number generator 120 may generate a 10-bit random number (RN) of "1011010100 ". The return qubit generating unit 130 may generate the application order SO of the first and second gates of "XZXXZXZXZZ" based on the random number RN of "1011010100 ". The return qubit generating unit 130 generates the return qubit generating unit 130 based on the application order SO of the first and second gates of "XZXXZXZXZZ" Third, fourth, sixth and eighth return cue bits of the first return queue bit group (RQG1) by applying the first gate to the first, second and sixth queue bits, The second gates are applied to the second, fifth, seventh, ninth and tenth qubits of the qubit group QG1 so that the second, fifth, and sixth qubits of the first return qubit group RQG1 7, 9 < th > and 10 < th > return cue bits.

In one embodiment, the first qubit (| 0>) generated based on the calculation base and the first return qubit (| 1> generated by applying the Pauligi gate to the first qubit, ) May have different values. The third return qubit (| +>) generated by applying the Pauligi X gate to the third qubit and the third qubit (| +>) generated based on the Hadamard basis are identical Value. ≪ / RTI > Wherein the second qubit (| 1 >) generated based on the calculation base and the second return qubit (| 1 >) generated by applying the Pauligi gate to the second qubit have the same value Lt; / RTI > The fifth return qubit (| +>) generated by applying the Fourier Z gate to the fifth qubit and the fifth qubit (| ->) generated based on the Hadamard basis are mutually different from each other It can have different values.

The transmitting and receiving unit 110 may transmit the first return queue bit group RQG1 to the first user terminal 200 and the transmitting and receiving unit 250 may receive the first return queue bit group RQG1 from the server 100 can do.

The key generation unit 260 may acquire a plurality of key bits KB1 by comparing the first qubit group QG1 with the first return queue bit group RQG1. For example, the key generation unit 260 may determine whether the first qubits of the first qubit group QG1 and the first return qubit of the first return queue bit group RQG1 are the same, It is possible to obtain the first key bit of the plurality of key bits (KB1) based on the kind of the base used at the occurrence of one qubit. For example, like the random number RN, the plurality of key bits KB1 may be a binary number of N bits.

As shown in FIG. 6, the operation of generating the plurality of key bits KB1 of the first user terminal 200 may be described based on the case where N is 10. [ For example, the key generation unit 260 compares the first to tenth queue bits with the first to tenth return queue bits, and generates a plurality of key bits (KB1 Can be obtained. For example, since the first qubit (| 0>) and the first return qubit (| 1>) generated on the basis of the calculation base have different values, (E.g., "1") corresponding to the first gate. Wherein the second key bit has a value corresponding to the second gate, the second key bit having a value equal to the second return key bit, (E.g., "0"). The third key bit generated based on the Hadamard basis has the same value as the third return qubit (| +>), so that the third key bit corresponds to the first gate And may be determined to be the first bit value (e.g., "1"). The fifth key bit (| ->) and the fifth return key bit (| +>) generated based on the Hadamard basis have different values, so that the fifth key bit corresponds to the second gate (For example, "0").

The channel 202 may be the quantum channel or the secure channel, and the channel 204 may be the classical channel or the public channel. The first queue bit group QG1 and the first return queue bit group RQG1 may be transmitted through the channel 202. [ For example, the channel 204 may operate based on the TCP / IP protocol.

In one embodiment, some or all of the components of server 100 and first user terminal 200 may be implemented in the form of a program (i.e., software) or hardware.

Although not shown, the server 100 and the first user terminal 200 may include a processor that executes various computing functions, such as certain calculations or tasks, a memory that stores data, instructions, etc., A post-processing unit for performing information reconciliation and privacy amplification to be described later with reference to FIG. 8, an encoding unit and a decoding unit for performing secure communication, which will be described later with reference to FIG. 8, May be further included.

Referring to FIG. 7, the key distribution operation of the server 100 and the second user terminal 300 is performed by the key distribution operation of the server 100 and the first user terminal 200 described above with reference to FIGS. 3 to 6, . ≪ / RTI > Similar to the first user terminal 200, the second user terminal 300 may include a random number generator, a base determiner, a data provider, a qubit generator, a transceiver, and a key generator.

The second user terminal 300 can generate the second base group BG2 composed of the combination of the first and second bases and generate the second qubits group QG2 based on the second base group BG2 Lt; / RTI > For example, as shown in Fig. 7, a second base group BG2 of "x + x + x + xx + x" may be generated based on the first random number RN1 of "0101010010" , And second data of "1010001001" based on the second base group BG2 of "× + × + × + ×× + ×" to generate the second qubit group QG2.

The server 100 may apply one of the first and second gates to each of the qubits included in the second queue group QG2 to generate a second queue group RQG2. For example, based on the application sequence SO of the first and second gates of "XZXXZXZXZZ" as shown in Fig. 7, the first, third, Applying the first gate to the sixth and eighth queue bits and applying the second gate to the second, fifth, seventh, ninth and tenth queue bits of the second queue bit group QG2 , And a second return queue bit group (RQG2).

The second user terminal 300 may obtain a plurality of key bits KB2 by comparing the second queue bit group QG2 with the second return queue bit group RQG2.

As described above, the first qubit group QG1 generated by the first user terminal 200 and the second qubit group QG2 generated by the second user terminal 300 may be different from each other, Since the server 100 applies the first and second gates in the same order (SO) to the qubit groups QG1 and QG2, the return queue bit groups RQG1, and RQG2 may include the same information associated with the key bits. Thus, the plurality of key bits (KB1) obtained by the first user terminal (200) and the plurality of key bits (KB2) obtained by the second user terminal (300) may be substantially the same.

Although not shown, the key distribution operation of the server 100 and the remaining user terminals 400 and 500 may also be performed by the key distribution operation of the server 100 and the first user terminal 200 described above with reference to FIGS. . ≪ / RTI >

In one embodiment, a key distribution operation may be performed sequentially for each of the user terminals 200, 300, 400, 500. For example, steps S100 through S400 of FIG. 3 may be performed for the first user terminal 200, and then steps S100 through S400 of FIG. 3 may be performed for the second user terminal 300, Steps S100 through S400 of FIG. 3 may then be performed for the third user terminal 400, and steps S100 through S400 of FIG. 3 may then be performed for the fourth user terminal 500. FIG.

In another embodiment, the key distribution operation for both user terminals 200, 300, 400, 500 may be performed substantially concurrently. For example, step S100 of FIG. 3 may be performed for user terminals 200, 300, 400, 500, and then step S200 of FIG. 3 for user terminals 200, 300, 400, 3 may be performed for the user terminals 200, 300, 400, 500, and thereafter, for the user terminals 200, 300, 400, 500, Step S400 of step 3 may be performed.

8 is a flowchart illustrating a quantum communication method according to embodiments of the present invention.

Referring to FIGS. 1 and 8, in a quantum communication method according to embodiments of the present invention, a plurality of user terminals 200, 300, 400, and 500 generate a plurality of base groups (step S1100) The server 100 generates a plurality of groups of qubits based on the plurality of base groups and transmits them to the server 100 in step S1200. , Generating a plurality of return queue bit groups by changing or maintaining each of the plurality of queue bits included in the plurality of queue bit groups, and transmitting the plurality of return queue bit groups to the user terminals 200 and 300 The user terminals 200, 300, 400, and 500 compare the plurality of the qubit groups with the plurality of return queue bit groups to generate a plurality of key bits (Step S1400). Steps S1100 to S1400 of Fig. 8 may be substantially the same as steps S100 to S400 of Fig. 3, respectively.

The server 100 and the user terminals 200, 300, 400, and 500 perform the information adjustment and the confidentiality amplification on the plurality of key bits to share the security key (step S1500). The server 100 and the user terminals 200, 300, 400, and 500 encrypt and exchange data based on the security key (step S1600).

The information coordination may be an operation for ensuring the identity of the security key. Specifically, the plurality of key bits transmitted from the server 100 by noise and / or interference, and the plurality of key bits received between the user terminals 200, 300, 400, A discrepancy (e.g., a channel error or an error due to a third party's eavesdropping) may be resolved by the information coordination. For example, an error correction code may be used to adjust the discrepancy, and therefore the information adjustment may be referred to as error correction.

The confidentiality amplification may be an operation for removing information leaked to a third party in the plurality of key bits. Specifically, the confidentiality amplification may indicate an operation of removing information leaked to a third party in the course of acquiring the common security key of the server 100 and the user terminals 200, 300, 400, and 500 . Although the length of the security key may be reduced by the secrecy amplification than the length of the plurality of key bits, randomness, security, security and / or confidentiality of the security key can be secured.

The above information coordination and confidentiality amplification may be a post-process technique and may be performed by a separate post-processing unit (not shown) within the server 100 and the user terminals 200, 300, 400, Lt; / RTI > By the information adjustment and the confidentiality amplification, the server 100 and the user terminals 200, 300, 400, and 500 can securely share the same security key.

In one embodiment, the plurality of qubits groups and the plurality of return queue bit groups may be used to control quantum channels (e.g., FIG. 1) between server 100 and user terminals 200, 300, 400, A solid line arrow of FIG. The information coordination and the privacy amplification may be performed through a public channel (e.g., a dashed arrow in FIG. 1) between the server 100 and the user terminals 200, 300, 400,

The plurality of key bits may be referred to as a raw key or a sifted key, and the secret key may be referred to as a final key. After the key distribution operation, the actual data exchange operation may be performed based on the security key which is the final key.

In one embodiment, the number of bits of the secret key may be less than the number of the plurality of key bits. For example, the secret key may have a relatively small number of bits. However, as the number of bits of the security key increases, it is advantageous. For example, as the number of bits of the security key increases, the performance and accuracy of secure communication can be improved.

In one embodiment, the data exchanged in step S1600 may be encrypted by a one-time pad scheme using the security key. However, the encryption method of the data can be variously changed according to the embodiment.

In the quantum communication method according to the embodiments of the present invention, the server 100 does not generate the qubits directly but transmits the qubits generated in the user terminals 200, 300, 400, 300, 400, 500 by transferring the qubits back to the user terminals 200, 300, 400, 500 after selectively applying the two keys to the user terminals 200, 300, 400, have. Thus, the load of the server 100 can be reduced, and the user terminals 200, 300, 400, and 500 can efficiently share the same key bits. Also, since the public channel is used only when the information coordination and the privacy amplification are performed, the use of the public channel for generating the secret key may be reduced, and entanglement and use of a quantum memory May be unnecessary.

The multi-party key exchange method and / or the quantum communication method in the quantum communication according to the embodiments of the present invention can be applied to any mobile device or any computing system and is included in the quantum communication system according to the embodiments of the present invention The server and user terminals may be any mobile device or any computing system. For example, the mobile device may be a mobile phone, a smart phone, a tablet PC, a laptop computer, a personal digital assistant (PDA), a portable multimedia And may include a portable multimedia player (PMP), a digital camera, a music player, a portable game console, a navigation system, and the like, and may be a wearable device, An Internet of Things (IoT) device, an Internet of Everything (IoE) device, an e-book, and the like. The computing system may include a personal computer (PC), a server computer, a workstation, a digital television, a set-top box, and the like.

The multi-party key exchange method, the quantum communication method and / or the quantum communication system in the quantum communication according to embodiments of the present invention may be embodied in the form of a product including computer readable program code stored in a computer- . The computer readable program code may be provided to the processor of the various computers or other data processing apparatus via a reading device. The computer-readable medium may be a computer-readable signal medium or a computer-readable recording medium. The computer-readable recording medium may be any type of medium that can store or contain programs in or on the instruction execution system, equipment or apparatus.

Although embodiments of the present invention have been described in detail above with reference to a quantum communication system that transmits signals using the rotation state of electrons, embodiments of the present invention may use a polarization of a photon, The present invention can also be applied to a quantum communication system in which a signal is transmitted using a wireless communication system.

The present invention can be applied to various communication apparatuses and communication systems. Therefore, the present invention can be applied to a mobile phone, a smart phone, a PDA, a PMP, a digital camera, a camcorder, a PC, a server computer, a workstation, a notebook, a digital TV, a set- And the like can be usefully used in various electronic devices.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims. It will be understood.

Claims (20)

A method comprising: generating a plurality of base groups, wherein a plurality of user terminals comprise a combination of a first basis and a second basis;
The plurality of user terminals generating and transmitting to the server a plurality of groups of qubits each including a plurality of qubits based on the plurality of base groups;
Wherein the server modifies or maintains each of the plurality of qubits contained in the plurality of qubits groups based on a first gate and a second gate to generate a plurality of return queue bit groups, Sending return queue bit groups to the plurality of user terminals; And
The plurality of user terminals comparing the plurality of qubits groups with the plurality of return queue bit groups to obtain a plurality of key bits for generating a secret key, Multi - way key distribution method. 2. The method of claim 1, wherein the first user terminal of the plurality of user terminals comprises:
Generating a first base group including a combination of the first base and the second base,
Generates a first qubit group including first to Nth (N is a natural number equal to or greater than 2) qubits based on the first base group, and transmits the generated first qubit group to the server,
And comparing the first queue bit group with a first return queue bit group transmitted from the server to obtain the plurality of key bits. 3. The server according to claim 2,
Applying one of the first gate and the second gate to each of the first through N th queue bits to generate each of first through N th return queue bits included in the first return queue bit group,
Wherein the value of the plurality of key bits is determined based on an application sequence of the first gate and the second gate. 4. The server according to claim 3,
Generating the first return qubit by applying the first gate to the first qubit if the first key bit of the plurality of key bits is to be set to a first bit value,
And generates the first return qubit by applying the second gate to the first qubit when it is desired to set the first key bit to a second bit value different from the first bit value Multiparty key distribution method in quantum communication. 5. The method of claim 4,
Wherein when the first qubit is generated based on the first basis, the first return qubit generated by applying the first gate to the first qubit and the first queue have different values ,
Wherein when the first qubit is generated based on the second basis, the first return qubit generated by applying the first gate to the first qubit and the first qubit have the same value A multi-party key distribution method in quantum communication. 6. The method of claim 5,
Wherein when the first qubit is generated based on the first basis, the first return qubit generated by applying the second gate to the first qubit and the first qubit have the same value,
Wherein when the first qubit is generated based on the second basis, the first return qubit generated by applying the second gate to the first qubit and the first qubit generated by applying the second gate to the first qubit, Lt; RTI ID = 0.0 > a < / RTI > multi-party key distribution in a quantum communication. 5. The method of claim 4,
The first basis is a computational basis for representing the spin down or spin up of electrons on a vertical axis,
Wherein the second basis is a Hadamard basis for representing the spin-down or the spin-up of the electrons on a horizontal axis. 8. The method of claim 7,
Wherein the first gate comprises a Pauli X gate operating as a NOT gate for changing the value of the first qubit when the first qubit is generated on the basis of the calculation, ego,
The second gate is a Pauli Z gate (Pauli Z gate) operating as the undefined gate for changing the value of the first qubit when the first qubit is generated based on the Hadamard basis A multi-party key distribution method in quantum communication. 9. The method of claim 8,
Wherein the first bit value is one and the second bit value is zero. The method according to claim 1,
Wherein all of the plurality of user terminals and the server share the same plurality of key bits. A method comprising: generating a plurality of base groups, wherein a plurality of user terminals comprise a combination of a first basis and a second basis;
The plurality of user terminals generating and transmitting to the server a plurality of groups of qubits each including a plurality of qubits based on the plurality of base groups;
Wherein the server modifies or maintains each of the plurality of qubits contained in the plurality of qubits groups based on a first gate and a second gate to generate a plurality of return queue bit groups, Sending return queue bit groups to the plurality of user terminals;
The plurality of user terminals comparing the plurality of the qubit groups and the plurality of return qubit groups to obtain a plurality of key bits;
The server and the plurality of user terminals performing information reconciliation and privacy amplification on the plurality of key bits to share a secret key; And
And the server and the plurality of user terminals encrypt and exchange data based on the security key. 12. The method of claim 11,
Wherein the plurality of qubit groups and the plurality of return queue bit groups are transmitted on a quantum channel between the server and the plurality of user terminals,
Wherein the information coordination and the privacy amplification are performed through a public channel between the server and the plurality of user terminals. 12. The method of claim 11,
Wherein the number of bits of the security key is less than the number of the plurality of key bits. 12. The method of claim 11,
Wherein the data is encrypted by a one-time pad method using the secret key. Generating a plurality of base groups consisting of a combination of a first basis and a second basis and generating a plurality of groups of qubits each including a plurality of qubits based on the plurality of base groups A plurality of user terminals; And
Receiving the plurality of qubits groups and modifying or maintaining each of the plurality of qubits contained in the plurality of qubits groups based on a first gate and a second gate to generate a plurality of return qubit groups And a server for transmitting the plurality of return queue groups to the plurality of user terminals,
Wherein the plurality of user terminals compares the plurality of qubits groups with the plurality of return queue bit groups to obtain a plurality of key bits for generating a security key. 16. The method of claim 15,
Wherein a first user terminal of the plurality of user terminals generates a first base group consisting of a combination of the first base and the second base, A second queue bit group including at least two natural numbers of two or more qubits, and transmits the first queue bit group to the server, compares the first queue bit group with a first return queue bit group transmitted from the server, ≪ / RTI >
Wherein the server applies one of the first gate and the second gate to each of the first through the N-th queue bits to generate first through N-th return queue bits included in the first return queue bit group And determines the value of the plurality of key bits based on the application order of the first gate and the second gate. 17. The server of claim 16,
Generating the first return qubit by applying the first gate to the first qubit if the first key bit of the plurality of key bits is to be set to a first bit value,
And generates the first return qubit by applying the second gate to the first qubit when it is desired to set the first key bit to a second bit value different from the first bit value Quantum communication system. 18. The method of claim 17,
Wherein when the first qubit is generated based on the first basis, the first return qubit generated by applying the first gate to the first qubit and the first queue have different values ,
Wherein when the first qubit is generated based on the second basis, the first return qubit generated by applying the first gate to the first qubit and the first qubit have the same value Wherein the quantum communication system comprises: 19. The method of claim 18,
Wherein when the first qubit is generated based on the first basis, the first return qubit generated by applying the second gate to the first qubit and the first qubit have the same value,
Wherein when the first qubit is generated based on the second basis, the first return qubit generated by applying the second gate to the first qubit and the first qubit generated by applying the second gate to the first qubit, And a quantum communication system. 16. The method of claim 15,
Wherein the server and the plurality of user terminals perform information reconciliation and privacy amplification on the plurality of key bits to share the secret key,
Wherein the server and the plurality of user terminals encrypt and exchange data based on the security key.

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