JP4622866B2 - Quantum cryptographic communication system, quantum cryptographic key distribution method used therefor, communication device, and cryptographic communication method used therefor - Google Patents

Description

The present invention is a quantum cryptographic communication system and method quantum key distribution, communication apparatus and related to the cryptographic communication method, and more particularly to a quantum cryptography communication system for performing communication using the quantum cryptography.

  In recent years, with the spread of the Internet and the like, data communicated via the Internet and the like is encrypted and transmitted / received to prevent eavesdropping. However, since conventional encryption techniques can be decrypted over time, quantum cryptography has been proposed as a physically secure communication method. The quantum cipher is not a cipher based on a number sequence that is currently generally used, but a cipher that is physically guaranteed by the principle of quantum mechanics.

  In conventional encryption communication, since encryption is performed using mathematical formulas, when optical communication is performed, strong light, that is, a large amount of photons is transmitted so that the data can surely reach the receiving side.

  In contrast, quantum cryptography uses only one photon when performing optical communication in order to extract the physical properties of the quantum. That is, in the quantum cryptography, 1-bit data (“0” or “1”) is transmitted by one photon.

  A configuration example of a conventional quantum cryptography communication system is shown in FIG. In conventional quantum cryptography communication, first, the base station 5 and the base station 6 generate a shared key in the quantum cryptography communication devices 51 and 61 according to a quantum cryptography protocol (see, for example, Non-Patent Document 1) (FIG. 11 701). The quantum cryptography communication devices 51 and 61 are connected by an optical fiber 700.

  Next, the data transmitter / receiver 52 of the base station 5 encrypts the plaintext (= the unencrypted text) using the generated shared key (the Burnham ciphertext 702), and the Burnham ciphertext 702 is converted to the base station 6. Send to. The data transmitter / receiver 62 of the base station 6 decrypts the Burnham ciphertext 702 using the shared key to obtain the original plaintext. The data transceivers 52 and 62 are connected by a data transmission path 703 such as a public network or the Internet network.

  Here, as an example of a method for encrypting plaintext using a shared key, an example is shown in which a Burnham encryption method using a one-time one-time pad is used. In the Burnham encryption system, plaintext is encrypted by a logical operation bit by bit with a random number key, and the ciphertext is decrypted with the same key.

Japanese National Publication No. 9-502323 "An Autocompensating Fiber-Optic Quantum Cryptography System Based on Polarization Splitting of Light" (Donald S.Bethune and Wikkiam P.Risk, IEEE Journal of Quantum Electronics vol.36, NO.3, MARCH 2000, pp.340-347)

  In the conventional quantum cryptography communication system described above, in the quantum cryptography communication protocol, very weak light having an average number of photons contained in 1 bit of 1 or less is used. The distance between stations is limited to about 100 km at most.

  That is, the communication method of encryption communication using the Burnham ciphertext is the same as that of normal optical communication or other communication, and the communication distance is not particularly limited, but is necessary for encryption and decryption. Since the distance between base stations in the generation of the shared key is limited to about 100 km, there is a problem that the distance at which encrypted communication can be performed is also limited to that level. That is, in the conventional quantum cryptography communication system, the distance between base stations when generating a shared key is limited to about 100 km at most, and key distribution beyond that distance is impossible.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to distribute a quantum cryptography shared key to a distant data communication device exceeding 100 km, which has conventionally not been able to directly generate a quantum cryptography shared key. how the quantum cryptographic communication system and its quantum key distribution can, in communication devices and to provide the encryption communication method.

The first quantum cryptography communication system according to the present invention includes at least a first communication device, a second communication device, and a third communication device,
A first shared key is generated between the first communication device and the second communication device using weak light by a quantum cryptography protocol,
A second shared key is generated between the second communication device and the third communication device using weak light by the quantum cryptography protocol, and
The second communication device encrypts the first shared key itself using the second shared key and then transmits it to the third communication device;
The third communication device decrypts the encrypted first shared key using the second shared key;
Plain text transmitted from the first communication apparatus to the third communication apparatus or plain text transmitted from the third communication apparatus to the first communication apparatus using the first shared key in a shared key system. It is encrypted and transmitted through a different route from the transmission of the first shared key .

A second quantum cryptography communication system according to the present invention includes at least a first communication device, second to N-1th communication devices (N is a positive integer of 3 or more), and an Nth communication device. Have
A first shared key is generated between the first communication device and the second communication device using weak light by a quantum cryptography protocol,
The second to N-1 shared keys are generated between the second communication device and the Nth communication device by using the weak light by the quantum cryptography protocol, respectively.
The second communication device encrypts the first shared key itself using the second shared key and then transmits it to the third communication device;
The third to (N-1) th communication devices decrypt the first shared key using the second to (N-2) th shared keys, respectively, and the decrypted first shared key itself is After encrypting each of the third to (N-1) -th shared keys and transmitting to the fourth to N-th communication devices,
The Nth communication device decrypts the first shared key encrypted by the N-1th communication device using the N-1th shared key;
Plain text transmitted from the first communication apparatus to the Nth communication apparatus or plaintext transmitted from the Nth communication apparatus to the first communication apparatus using the first shared key in a shared key system. It is encrypted and transmitted through a different route from the transmission of the first shared key .

The third quantum cryptography communication system according to the present invention includes at least a first communication device, a second communication device, and third and fourth communication devices,
Generating a first and a second shared key between the first communication device and the second communication device using weak light by a quantum cryptography protocol;
Generating a third shared key between the second communication device and the third communication device using weak light by the quantum cryptography protocol;
Generating a fourth shared key between the second communication device and the fourth communication device using weak light by the quantum cryptography protocol;
The second communication device encrypts the first shared key itself using the third shared key, and then transmits it to the third communication device;
The second communication device encrypts the second shared key itself using the fourth shared key, and then transmits it to the fourth communication device;
The third communication device decrypts the first shared key encrypted by the second communication device using the third shared key;
The fourth communication device decrypts the second shared key encrypted by the second communication device using the fourth shared key;
Plain text transmitted from the first communication apparatus to the third communication apparatus or plain text transmitted from the third communication apparatus to the first communication apparatus using the first shared key in a shared key system. Encrypted and transmitted on a different route from the transmission of the first shared key ,
Plain text transmitted from the first communication apparatus to the fourth communication apparatus or plain text transmitted from the fourth communication apparatus to the first communication apparatus using the second shared key in a shared key system. It is encrypted and transmitted through a different route from the transmission of the second shared key .

The fourth quantum cryptography communication system according to the present invention includes at least a first communication device, and second and third communication devices,
A first shared key is generated between the first communication device and the second communication device using weak light by a quantum cryptography protocol,
A second shared key is generated between the first communication device and the third communication device using weak light by the quantum cryptography protocol;
A third shared key is generated between the second communication device and a next-stage communication device adjacent to the second communication device using weak light by the quantum cryptography protocol;
A fourth shared key is generated between the third communication device and a next-stage communication device adjacent to the third communication device using weak light by the quantum cryptography protocol;
The second communication device encrypts the first shared key itself using the third shared key and then transmits it to the next-stage communication device adjacent thereto,
The third communication device encrypts the second shared key itself using the fourth shared key and then transmits it to the next-stage communication device adjacent thereto,
The next-stage communication device adjacent to the second communication device decrypts the first shared key encrypted by the second communication device using the third shared key,
The next-stage communication device adjacent to the third communication device decrypts the second shared key encrypted by the third communication device using the fourth shared key,
Plain text transmitted from the first communication device to the next-stage communication device adjacent to the second communication device, or next-stage communication device adjacent to the second communication device transmitted to the first communication device. The plaintext is encrypted by the shared key method using the first shared key and transmitted through a path different from the transmission of the first shared key ,
Plain text transmitted from the first communication device to the next-stage communication device adjacent to the third communication device, or next-stage communication device adjacent to the third communication device transmitted to the first communication device. The plaintext is encrypted by the shared key method using the second shared key, and transmitted through a route different from the transmission of the second shared key .

A first quantum encryption key distribution method according to the present invention is a quantum encryption key distribution method used in a quantum encryption communication system including at least a first communication device, a second communication device, and a third communication device. And
Generating a first shared key between the first communication device and the second communication device using weak light by a quantum cryptography protocol;
Generating a second shared key between the second communication device and the third communication device using weak light by the quantum cryptography protocol;
A step of encrypting the first shared key itself using the second shared key in the second communication device and then transmitting to the third communication device;
Decrypting the encrypted first shared key using the second shared key in the third communication device;
Plain text transmitted to the third communication apparatus in the first communication apparatus or plain text transmitted to the first communication apparatus by the third communication apparatus using the first shared key in a shared key system And a procedure for encrypting and transmitting the first shared key via a different route .

A second quantum key distribution method according to the present invention includes at least a first communication device, second to N-1th communication devices (N is a positive integer of 3 or more), and an Nth communication device. A quantum cryptography key distribution method for use in a quantum cryptography communication system comprising:
Generating a first shared key between the first communication device and the second communication device using weak light by a quantum cryptography protocol;
A procedure of generating second to (N-1) -th shared keys between the second communication device and the N-th communication device using weak light according to the quantum cryptography protocol;
A step of encrypting the first shared key itself using the second shared key in the second communication device and then transmitting to the third communication device;
In the third to (N-1) th communication devices, the first to the second shared key is decrypted using the second to (N-2) th shared keys, and the decrypted first shared key itself is used as the first shared key. A procedure of transmitting to the fourth to Nth communication apparatuses after encrypting each using a 3rd to (N-1) th shared key;
Decrypting the first shared key encrypted by the N-1th communication device using the N-1th shared key in the Nth communication device;
Plain text transmitted from the first communication apparatus to the Nth communication apparatus or plaintext transmitted from the Nth communication apparatus to the first communication apparatus using the first shared key in a shared key system. And a procedure for encrypting and transmitting the first shared key via a different route .

The third quantum encryption key distribution method according to the present invention is a quantum encryption key distribution used in a quantum encryption communication system comprising at least a first communication device, a second communication device, and third and fourth communication devices. A method,
A procedure for generating first and second shared keys between the first communication device and the second communication device using weak light according to a quantum cryptography protocol;
A procedure for generating a third shared key between the second communication device and the third communication device using weak light by the quantum cryptography protocol;
A procedure for generating a fourth shared key between the second communication device and the fourth communication device using weak light by the quantum cryptography protocol;
A step of encrypting the first shared key itself using the third shared key in the second communication device and then transmitting the encrypted key to the third communication device;
A procedure of transmitting the second shared key itself after encrypting the second shared key itself using the fourth shared key in the second communication device;
A procedure in which the third communication device decrypts the first shared key encrypted by the second communication device using the third shared key;
The fourth communication device decrypting the second shared key encrypted by the second communication device using the fourth shared key;
Plain text transmitted from the first communication apparatus to the third communication apparatus or plain text transmitted from the third communication apparatus to the first communication apparatus using the first shared key in a shared key system. A procedure of encrypting and transmitting through a different route from the transmission of the first shared key ;
Plain text transmitted from the first communication apparatus to the fourth communication apparatus or plain text transmitted from the fourth communication apparatus to the first communication apparatus using the second shared key in a shared key system. And a procedure for encrypting and transmitting via a different route from the transmission of the second shared key .

A fourth quantum encryption key distribution method according to the present invention is a quantum encryption key distribution method used for a quantum encryption communication system including at least a first communication device and second and third communication devices,
Generating a first shared key between the first communication device and the second communication device using weak light by a quantum cryptography protocol;
Generating a second shared key between the first communication device and the third communication device using weak light by the quantum cryptography protocol;
A procedure for generating a third shared key using weak light by the quantum cryptography protocol between the second communication device and the next-stage communication device adjacent to the second communication device;
A procedure for generating a fourth shared key using weak light by the quantum cryptography protocol between the third communication device and the next-stage communication device adjacent to the third communication device;
A procedure in which the second communication device encrypts the first shared key itself using the third shared key and then transmits it to the next-stage communication device adjacent thereto;
A procedure in which the third communication device encrypts the second shared key itself using the fourth shared key and then transmits it to the next-stage communication device adjacent thereto;
A procedure in which the next-stage communication device adjacent to the second communication device decrypts the first shared key encrypted by the second communication device using the third shared key;
A next-stage communication device adjacent to the third communication device decrypts the second shared key encrypted by the third communication device using the fourth shared key;
Plain text transmitted from the first communication device to the next-stage communication device adjacent to the second communication device, or next-stage communication device adjacent to the second communication device transmitted to the first communication device. A procedure of encrypting plaintext using the first shared key by a shared key method and transmitting the plaintext through a path different from the transmission of the first shared key ;
Plain text transmitted from the first communication device to the next-stage communication device adjacent to the third communication device, or next-stage communication device adjacent to the third communication device transmitted to the first communication device. And a procedure for encrypting plaintext using the second shared key by a shared key method and transmitting the plaintext through a different route from the transmission of the second shared key .

A first communication device according to the present invention is a communication device that performs quantum cryptography communication,
Means for generating a first shared key using weak light by a quantum cryptography protocol with the first communication device;
Means for receiving a second shared key generated between the first communication device and the second communication device, wherein the first communication device is encrypted and transmitted using the first shared key When,
Means for decrypting the second shared key using the first shared key;
Means for transmitting / receiving plaintext to / from the second communication device using a path different from the transmission of the second shared key using the second shared key .

A second communication device according to the present invention is a communication device that performs quantum cryptography communication,
Means for generating a first shared key using weak light by a quantum cryptography protocol with the first communication device;
The second communication device is encrypted by the first communication device with a second shared key generated using weak light by a quantum cryptography protocol between the first communication device and the second communication device. Means for transmitting and receiving plaintext to and from the second communication device using a path different from the transmission of the first shared key using the first shared key relayed to the communication device.

A first encryption communication method of the present invention is an encryption communication method used for a communication device that performs quantum encryption communication,
The communication device is
Generating a first shared key with weak light using a quantum cryptography protocol with the first communication device;
Receiving a second shared key generated between the first communication device and the second communication device , which is transmitted by the first communication device encrypted using the first shared key. When,
Decrypting the second shared key using the first shared key;
A step of transmitting and receiving plaintext to and from the second communication device using a path different from the transmission of the second shared key using the second shared key.

A second cryptographic communication method of the present invention is a cryptographic communication method used for a communication device that performs quantum cryptographic communication,
The communication device is
Generating a first shared key with weak light using a quantum cryptography protocol with the first communication device;
The second communication device is encrypted by the first communication device with a second shared key generated using weak light by a quantum cryptography protocol between the first communication device and the second communication device. Using the first shared key relayed to the communication device, a step of transmitting / receiving plaintext to / from the second communication device through a different path from the transmission of the first shared key is executed.

  That is, the quantum cryptography communication system of the present invention provides a method for distributing a shared key in quantum cryptography communication to a distant data communication apparatus (for example, a base station) that has been impossible to distribute conventionally. When the distance between the first and second data communication devices that match each other and the distance between the second and third data communication devices is less than 100 km and communication is performed between the first and third data communication devices, the second By relaying and transmitting the quantum cryptography shared key in the data communication apparatus, it becomes possible to distribute the shared key to a distant data communication apparatus exceeding 100 km.

  More specifically, the quantum key distribution method of the quantum cryptography communication system according to the present invention includes at least a first data communication device that is a key distribution source and a second data communication device that is a key relay station. And a procedure for generating a shared key K1 by a quantum cryptography protocol between the first data communication device and the second data communication device in the configuration comprising the third data communication device to which the key is distributed. A procedure for generating the shared key K2 between the second data communication device and the third data communication device, and the second data communication device after encrypting the shared key K1 itself using the shared key K2 And a procedure for the third data communication device to decrypt the shared key K1 using the shared key K2.

  As described above, in the quantum cryptography communication system of the present invention, the quantum cryptography shared key from the first data communication device to the third data communication device is relayed and transmitted by the second data communication device. Thus, it becomes possible to distribute the quantum cryptography shared key to a third data communication device that is distant beyond 100 km for which the quantum cryptography shared key could not be directly generated.

  With the configuration and operation as described below, the present invention distributes a quantum cryptography shared key to distant data communication devices exceeding 100 km, which conventionally could not directly generate a quantum cryptography shared key. The effect that it can do is acquired.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a quantum cryptography communication system according to a first embodiment of the present invention. In FIG. 1, the quantum cryptography communication system according to the first embodiment of the present invention is composed of base stations 1 to 3, and between the base station 1 and the base station 2 and between the base station 2 and the base station 3, respectively. The optical fibers 101 and 102 are connected.

  In addition, between the base station 1 and the base station 2 and between the base station 2 and the base station 3, it is possible to generate a shared key for quantum cryptography according to a quantum cryptography protocol (see, for example, Non-Patent Document 1). In addition, each of the base stations 1 to 3 includes quantum cryptographic communication devices 11, 22, 22 and 31 that can perform encrypted communication using the quantum cryptographic key. However, the distance between the base station 1 and the base station 3 is 100 km or more, and the quantum cryptography shared key cannot be directly generated.

  Further, the base station 1 and the base station 3 are connected by a communication path 103 such as a public network, a mobile phone network, and an internet network, and the data transceivers 12 and 32 of the base station 1 and the base station 3 respectively. Data transmission / reception is possible.

  FIG. 2 is a sequence chart showing a quantum cryptography shared key distribution operation in the quantum cryptography communication system according to the first exemplary embodiment of the present invention. With reference to FIGS. 1 and 2, the operation of distributing the shared key of the quantum cryptography in the quantum cryptography communication system according to the first embodiment of the present invention will be described.

  First, a quantum cryptography shared key K1 is generated between the base station 1 and the base station 2 by a quantum cryptography protocol (a1 in FIG. 2), and the quantum cryptography shared key between the base station 2 and the base station 3 is generated. K2 is generated (a2 in FIG. 2).

  Subsequently, the base station 2 encrypts the quantum cryptography shared key K1 itself using the quantum cryptography shared key K2 (burnum ciphertext 201) (a3 in FIG. 2), and transmits the barnum ciphertext 201 to the base station 3. (A4 in FIG. 2).

  The base station 3 obtains the quantum cryptography shared key K1 by decrypting the Vernam ciphertext 201 sent from the base station 2 using the quantum cryptography shared key K2 (a6 in FIG. 2). As a result, even if the plaintext encrypted using the quantum cryptography shared key K1 is sent by the base station 1 (a5, a7 in FIG. 2), the base station 3 sends the Vernam sent from the base station 1. A plaintext can be obtained by decrypting the ciphertext 301 using the quantum cryptography shared key K1 (a8 in FIG. 2).

  Thereby, in the present embodiment, the shared key K1 can be distributed by quantum cryptography from the base station 1 to the base station 3 with the distance of 100 km or more with the base station 2 as a relay point.

  Therefore, in the present embodiment, the shared key K1 of the quantum cipher from the base station 1 to the base station 3 is relay-transmitted by the base station 2 so that the shared key cannot be directly generated conventionally and exceeds 100 km. The shared key K1 of the quantum cryptography can be distributed to the remote base station 3. In this embodiment, Vernam encryption is used for encryption of the shared key K1 and plaintext, but other common key encryption can also be used.

  FIG. 3 is a block diagram showing a configuration of the quantum cryptography communication system according to the second exemplary embodiment of the present invention. In FIG. 3, the quantum cryptography communication system according to the second embodiment of the present invention relays the quantum cryptography shared key K1 one after another from the base station 2 to the base station 3 and from the base station 3 to the next base station. Thus, the shared key K1 of the quantum cryptography can be distributed to the base station N farther than the first embodiment of the present invention described above.

  FIG. 4 is a sequence chart showing the quantum cryptography shared key distribution operation in the quantum cryptography communication system according to the second embodiment of the present invention. With reference to FIG. 3 and FIG. 4, the operation of distributing the shared key of the quantum cryptography in the quantum cryptography communication system according to the second embodiment of the present invention will be described.

  First, a quantum cryptography shared key K1 is generated between the base station 1 and the base station 2 by a quantum cryptography protocol (b1 in FIG. 4), and the quantum cryptography shared key between the base station 2 and the base station 3 is generated. K2 is generated (b2 in FIG. 4), a quantum cryptography shared key K3 is generated between the base station 3 and the base station 4 (not shown) (b3 in FIG. 4), and the base station N-1 (not shown) The quantum cryptography shared key K (N-1) is generated with the base station N (b6 in FIG. 4). Are generated sequentially.

  Subsequently, the base station 2 encrypts the quantum cryptography shared key K1 itself using the quantum cryptography shared key K2 (burnum ciphertext) (b4 in FIG. 4), and transmits the barnum ciphertext to the base station 3. (B5 in FIG. 4). The base station 3 obtains the quantum cryptography shared key K1 by decrypting the Vernam ciphertext sent from the base station 2 using the quantum cryptography shared key K2 (b7 in FIG. 4).

  The base station 3 encrypts the quantum cryptography shared key K1 itself using the quantum cryptography shared key K3 (burnum ciphertext) (b8 in FIG. 4), and transmits the barnum ciphertext to the base station 4 (FIG. 4). As in b9), the adjacent base stations encrypt the quantum cryptography shared key K1 itself using the quantum cryptography shared keys K2 to K (N-1) and sequentially transmit them.

  The base station N obtains the quantum cryptography shared key K1 by decrypting the Vernam ciphertext sent from the base station N-1 using the quantum cryptography shared key K (N-1) (FIG. 4). b10, b11).

  Thus, in this embodiment, the shared key K1 of the quantum cryptography can be distributed from the base station 1 to the base station N with the distance of 100 km or more with the base stations 2 to N-1 as relay points.

  FIG. 5 is a block diagram showing the configuration of a quantum cryptography communication system according to a third embodiment of the present invention. In FIG. 5, in the quantum cryptography communication system according to the third embodiment of the present invention, the shared key K1A, K1B of the quantum cryptography is transmitted from the base station 1 to the base station 3 and the base station 4 using the base station 2 as a relay point, respectively. Distributed by relay transmission.

  Here, the base station 1 and the base station 2, the base station 2 and the base station 3, and the base station 2 and the base station 4 are connected by optical fibers 101, 102, and 104, respectively. In addition, each of the base stations 1 to 4 includes quantum cryptographic communication devices 13, 23, 24, 33, and 41 that can perform encrypted communication using a quantum cryptographic key.

  FIG. 6 is a sequence chart showing a quantum cryptography shared key distribution operation in the quantum cryptography communication system according to the third embodiment of the present invention. With reference to FIG. 5 and FIG. 6, the operation of distributing the quantum cryptography shared key in the quantum cryptography communication system according to the third embodiment of the present invention will be described.

  In this case, the base station 1 generates quantum cryptographic shared keys K1A and K1B with the base station 2 by the quantum cryptographic protocol (c1 and c2 in FIG. 6), and the base station 2 communicates with the base station 3. Then, a quantum cryptography shared key K23 is generated (c3 in FIG. 6), and a quantum cryptography shared key K24 is generated with the base station 4 (c4 in FIG. 6).

  Subsequently, the base station 2 encrypts the quantum cryptography shared key K1A itself using the quantum cryptography shared key K23 (burnum ciphertext 202) (c5 in FIG. 6), and transfers the Bernam ciphertext 202 to the base station 3. Transmit (c6 in FIG. 6). The base station 3 obtains the quantum cryptography shared key K1A by decrypting the Vernam ciphertext 202 sent from the base station 2 using the quantum cryptography shared key K23 (c9 in FIG. 6).

  Further, the base station 2 encrypts the quantum cryptography shared key K1B itself using the quantum cryptography shared key K24 (burnum ciphertext 203) (c7 in FIG. 6), and transmits the barnum ciphertext 203 to the base station 4. (C8 in FIG. 6). The base station 4 obtains the quantum cryptography shared key K1B by decrypting the Vernam ciphertext 203 sent from the base station 2 using the quantum cryptography shared key K24 (c10 in FIG. 6).

  Thus, in the present embodiment, the base station 2 serves as a relay point, the distribution of the quantum cryptography shared key K1A from the base station 1 to the base station 3 whose distance is 100 km or more, and the base station 1 to the base station 4 It is possible to distribute the shared key K1B of the quantum cryptography.

  FIG. 7 is a block diagram showing a configuration of a quantum cryptography communication system according to a fourth example of the present invention. In FIG. 7, in the quantum cryptography communication system according to the fourth embodiment of the present invention, quantum cryptography shared keys K1A and K1B are distributed from the base station 1 in a plurality of directions (two directions in FIG. 7).

  Here, between the base station 1 and the base station 2, between the base station 1 and the base station 3, between the base station 2 and the next base station, between the base station 3 and the next base station, respectively The optical fibers 101 and 105 to 107 are connected. In addition, each of the base stations 1 to 3 includes quantum cryptographic communication devices 14, 15, 25, 26, 34, and 35 that can perform encrypted communication using a quantum cryptographic key.

  In the present embodiment, the quantum key shared key K1A is transferred from the base station 1 to the next base station (not shown) using the base station 2 as a relay point, and similarly, the quantum key shared key K1B is transferred from the base station 1 to the next base station (not shown). The station 3 is distributed to the next base station (not shown) as a relay point.

  FIG. 8 is a sequence chart showing a quantum cryptography shared key distribution operation in the quantum cryptography communication system according to the fourth exemplary embodiment of the present invention. With reference to FIG. 7 and FIG. 8, the operation of distributing the quantum cryptography shared key in the quantum cryptography communication system according to the fourth embodiment of the present invention will be described.

  In this case, the base station 1 generates a quantum cryptography shared key K1A with the base station 2 by the quantum cryptography protocol (d1 in FIG. 8), and the quantum cryptography protocol with the base station 3 by the quantum cryptography protocol. A shared key K1B is generated (d2 in FIG. 8). Also, the base station 2 generates a quantum cipher shared key K2 with the next adjacent base station (d3 in FIG. 8), and the base station 3 shares the quantum cipher with the next adjacent base station. A key K3 is generated (d4 in FIG. 8).

  Therefore, the base station 2 encrypts the quantum cryptography shared key K1A itself using the quantum cryptography shared key K2 (burnum ciphertext 204) (d5 in FIG. 8), and passes the burnham ciphertext 204 to the next base station. Is transmitted (d6 in FIG. 8). At the next base station, the Vernam ciphertext 204 sent from the base station 2 is decrypted using the quantum cryptography shared key K2 to obtain the quantum cryptography shared key K1A.

  In addition, the base station 3 encrypts the quantum cryptography shared key K1B itself using the quantum cryptography shared key K3 (burnum ciphertext 205) (d7 in FIG. 8), and passes the barnum ciphertext 205 to the next base station. Is transmitted (d8 in FIG. 8). At the next base station, the Vernam ciphertext 205 sent from the base station 3 is decrypted using the quantum cryptography shared key K3 to obtain the quantum cryptography shared key K1B.

  Thus, in the present embodiment, the quantum key shared key K1A, the base station 2 and the base station 3 are used as relay points from the base station 1 whose distance is 100 km or more to the next base station existing in a plurality of directions. K1B can be distributed.

  FIG. 9 is a block diagram showing a configuration of a quantum cryptography communication system according to a fifth example of the present invention. In FIG. 9, in the quantum cryptography communication system according to the fourth exemplary embodiment of the present invention, a shared key (hereinafter referred to as a distribution key) K0 distributed from the base station 1 to the base station 3 is routed through a different path. By encrypting with the shared key K3 of the quantum cryptography distributed, and further encrypting and transmitting the encrypted distribution key K0 with the shared key K1 of the quantum cryptography used in the direction in which it is transmitted, The security of the distribution key K0 is increased.

  Here, between the base station 1 and the base station 2, between the base station 1 and the base station 4, between the base station 2 and the base station 3, and between the base station 4 and the base station 3 are respectively optical fibers. 101, 102, 108 and 109 are connected. In addition, each of the base stations 1 to 4 includes quantum cryptographic communication devices 16, 17, 27, 28, 36, 37, 42, and 43 that can perform encrypted communication using a quantum cryptographic key.

  In this embodiment, the distribution key K0 from the base station 1 is transmitted to the base station 3 using the base station 2 as a relay point, and the shared key K3 of the quantum cryptography used for encrypting the distribution key K0 is relayed to the base station 4. Distributed to the base station 3.

  FIG. 10 is a sequence chart showing a quantum cryptography shared key distribution operation in the quantum cryptography communication system according to the fifth embodiment of the present invention. With reference to FIGS. 9 and 10, the operation of distributing the shared key of the quantum cryptography in the quantum cryptography communication system according to the fifth embodiment of the present invention will be described.

  In this case, the base station 1 generates a quantum cryptography shared key K1 with the base station 2 by the quantum cryptography protocol (e1 in FIG. 10), and the quantum cryptography protocol with the base station 4 by the quantum cryptography protocol. A shared key K3 is generated (e2 in FIG. 10). Further, the base station 2 generates a quantum cryptographic shared key K2 with the base station 3 (e3 in FIG. 10), and the base station 4 generates a quantum cryptographic shared key K4 with the base station 3 ( E4) in FIG.

  The base station 1 encrypts the distribution key K0 to be distributed to the base station 3 using the quantum encryption shared key K3 with the base station 4 (e5 in FIG. 10), and the encrypted distribution key K0 (hereinafter, referred to as the distribution key K0). The composite key is encrypted using the quantum cryptography shared key K1 (Vernum ciphertext 206) (e6 in FIG. 10), and the Vernam ciphertext 206 is transmitted to the base station 2 (e7 in FIG. 10).

  On the other hand, the base station 4 encrypts the quantum cryptography shared key K3 itself using the quantum cryptography shared key K4 (burnum ciphertext 208) (e8 in FIG. 10), and transmits the barnum ciphertext 208 to the base station 3. (E9 in FIG. 10). The base station 3 obtains the quantum cryptography shared key K3 by decrypting the Vernam ciphertext 208 transmitted from the base station 4 using the quantum cryptography shared key K4 (e10 in FIG. 10).

  When the base station 2 obtains a composite key by decrypting the Vernam ciphertext 206 sent from the base station 1 using the quantum cryptography shared key K1 (e11 in FIG. 10), the base key 2 converts the composite key into the quantum cryptography. Is encrypted using the shared key K2 (burnum ciphertext 207) (e12 in FIG. 10), and the barnum ciphertext 207 is transmitted to the base station 3 (e13 in FIG. 10).

  When the base station 3 obtains a composite key by decrypting the Vernam ciphertext 207 sent from the base station 2 using the shared key K2 of the quantum cryptography (e14 in FIG. 10), the composite key is The distribution key K0 is obtained by decrypting the Vernam ciphertext 208 from the base station 4 by using the quantum cryptography shared key K3 obtained (FIG. 10, e15).

  As a result, in this embodiment, the base station 2 is used as a relay point, and the composite key is distributed to the base station 3 whose distance is 100 km or more, and the base station 4 is used as the relay point to the base station 3 for the distribution key K0. By distributing the quantum cryptography shared key K3 used for encryption (generation of the composite key), the distribution key K0 can be more securely distributed to the base station 3.

  INDUSTRIAL APPLICABILITY The present invention can be applied to fields requiring high security in data communication such as defense, diplomacy, and finance, and is applied to a data communication apparatus that relays data in addition to a base station. Is possible. Further, in the present invention, the Burnham cipher is used for the encryption of the shared key and the plaintext, but other common key ciphers can also be used.

It is a block diagram which shows the structure of the quantum cryptography communication system by 1st Example of this invention. It is a sequence chart which shows the distribution operation | movement of the shared key of quantum cryptography in the quantum cryptography communication system by 1st Example of this invention. It is a block diagram which shows the structure of the quantum cryptography communication system by the 2nd Example of this invention. It is a sequence chart which shows the distribution operation | movement of the shared key of the quantum cryptography in the quantum cryptography communication system by the 2nd Example of this invention. It is a block diagram which shows the structure of the quantum cryptography communication system by the 3rd Example of this invention. It is a sequence chart which shows distribution operation | movement of the shared key of the quantum cryptography in the quantum cryptography communication system by the 3rd Example of this invention. It is a block diagram which shows the structure of the quantum cryptography communication system by the 4th Example of this invention. It is a sequence chart which shows the distribution operation | movement of the shared key of the quantum cryptography in the quantum cryptography communication system by the 4th Example of this invention. It is a block diagram which shows the structure of the quantum cryptography communication system by the 5th Example of this invention. It is a sequence chart which shows distribution operation | movement of the shared key of the quantum cryptography in the quantum cryptography communication system by the 5th Example of this invention. It is a block diagram which shows the structure of the quantum cryptography communication system by a prior art example.

Explanation of symbols

1-N base stations 11, 13-17,
21-28, 31,
33-37, 41-43 Quantum cryptographic communication device
12, 32 Data transceivers 101, 102,
104-109 optical fiber
103 communication path

Claims (12)

Having at least a first communication device, a second communication device, and a third communication device;
A first shared key is generated between the first communication device and the second communication device using weak light by a quantum cryptography protocol,
A second shared key is generated between the second communication device and the third communication device using weak light by the quantum cryptography protocol, and
The second communication device encrypts the first shared key itself using the second shared key and then transmits it to the third communication device;
The third communication device decrypts the encrypted first shared key using the second shared key;
Plain text transmitted from the first communication apparatus to the third communication apparatus or plain text transmitted from the third communication apparatus to the first communication apparatus using the first shared key in a shared key system. A quantum cryptography communication system, wherein the quantum cryptography communication system is encrypted and transmitted through a path different from the transmission of the first shared key . At least a first communication device, second to (N-1) th (N is a positive integer of 3 or more) communication devices, and an Nth communication device,
A first shared key is generated between the first communication device and the second communication device using weak light by a quantum cryptography protocol,
The second to N-1 shared keys are generated between the second communication device and the Nth communication device by using the weak light by the quantum cryptography protocol, respectively.
The second communication device encrypts the first shared key itself using the second shared key and then transmits it to the third communication device;
The third to (N-1) th communication devices decrypt the first shared key using the second to (N-2) th shared keys, respectively, and the decrypted first shared key itself is After encrypting each of the third to (N-1) -th shared keys and transmitting to the fourth to N-th communication devices,
The Nth communication device decrypts the first shared key encrypted by the N-1th communication device using the N-1th shared key;
Plain text transmitted from the first communication apparatus to the Nth communication apparatus or plaintext transmitted from the Nth communication apparatus to the first communication apparatus using the first shared key in a shared key system. A quantum cryptography communication system, wherein encryption is performed and the transmission is performed through a different path from the transmission of the first shared key . Having at least a first communication device, a second communication device, and third and fourth communication devices,
Generating a first and a second shared key between the first communication device and the second communication device using weak light by a quantum cryptography protocol;
Generating a third shared key between the second communication device and the third communication device using weak light by the quantum cryptography protocol;
Generating a fourth shared key between the second communication device and the fourth communication device using weak light by the quantum cryptography protocol;
The second communication device encrypts the first shared key itself using the third shared key, and then transmits it to the third communication device;
The second communication device encrypts the second shared key itself using the fourth shared key, and then transmits it to the fourth communication device;
The third communication device decrypts the first shared key encrypted by the second communication device using the third shared key;
The fourth communication device decrypts the second shared key encrypted by the second communication device using the fourth shared key;
Plain text transmitted from the first communication apparatus to the third communication apparatus or plain text transmitted from the third communication apparatus to the first communication apparatus using the first shared key in a shared key system. Encrypted and transmitted on a different route from the transmission of the first shared key ,
Plain text transmitted from the first communication apparatus to the fourth communication apparatus or plain text transmitted from the fourth communication apparatus to the first communication apparatus using the second shared key in a shared key system. A quantum cryptography communication system, wherein the quantum cryptography communication system is encrypted and transmitted through a route different from the transmission of the second shared key . Having at least a first communication device and second and third communication devices;
A first shared key is generated between the first communication device and the second communication device using weak light by a quantum cryptography protocol,
A second shared key is generated between the first communication device and the third communication device using weak light by the quantum cryptography protocol;
A third shared key is generated between the second communication device and a next-stage communication device adjacent to the second communication device using weak light by the quantum cryptography protocol;
A fourth shared key is generated between the third communication device and a next-stage communication device adjacent to the third communication device using weak light by the quantum cryptography protocol;
The second communication device encrypts the first shared key itself using the third shared key and then transmits it to the next-stage communication device adjacent thereto,
The third communication device encrypts the second shared key itself using the fourth shared key and then transmits it to the next-stage communication device adjacent thereto,
The next-stage communication device adjacent to the second communication device decrypts the first shared key encrypted by the second communication device using the third shared key,
The next-stage communication device adjacent to the third communication device decrypts the second shared key encrypted by the third communication device using the fourth shared key,
Plain text transmitted from the first communication device to the next-stage communication device adjacent to the second communication device, or next-stage communication device adjacent to the second communication device transmitted to the first communication device. The plaintext is encrypted by the shared key method using the first shared key and transmitted through a path different from the transmission of the first shared key ,
Plain text transmitted from the first communication device to the next-stage communication device adjacent to the third communication device, or next-stage communication device adjacent to the third communication device transmitted to the first communication device. A quantum cryptography communication system, wherein plaintext is encrypted by a shared key method using the second shared key and transmitted through a path different from the transmission of the second shared key . A quantum cryptography key distribution method used in a quantum cryptography communication system comprising at least a first communication device, a second communication device, and a third communication device,
Generating a first shared key between the first communication device and the second communication device using weak light by a quantum cryptography protocol;
Generating a second shared key between the second communication device and the third communication device using weak light by the quantum cryptography protocol;
A step of encrypting the first shared key itself using the second shared key in the second communication device and then transmitting to the third communication device;
Decrypting the encrypted first shared key using the second shared key in the third communication device;
Plain text transmitted to the third communication apparatus in the first communication apparatus or plain text transmitted to the first communication apparatus by the third communication apparatus using the first shared key in a shared key system A quantum encryption key distribution method comprising: encrypting and transmitting the first shared key through a different route . Quantum cryptographic key distribution method used in a quantum cryptographic communication system comprising at least a first communication device, second to (N-1) th (N is a positive integer greater than or equal to 3) communication devices, and an Nth communication device Because
Generating a first shared key between the first communication device and the second communication device using weak light by a quantum cryptography protocol;
A procedure of generating second to (N-1) -th shared keys between the second communication device and the N-th communication device using weak light according to the quantum cryptography protocol;
A step of encrypting the first shared key itself using the second shared key in the second communication device and then transmitting to the third communication device;
In the third to (N-1) th communication devices, the first to the second shared key is decrypted using the second to (N-2) th shared keys, and the decrypted first shared key itself is used as the first shared key. A procedure of transmitting to the fourth to Nth communication apparatuses after encrypting each using a 3rd to (N-1) th shared key;
Decrypting the first shared key encrypted by the N-1th communication device using the N-1th shared key in the Nth communication device;
Plain text transmitted from the first communication apparatus to the Nth communication apparatus or plaintext transmitted from the Nth communication apparatus to the first communication apparatus using the first shared key in a shared key system. A quantum encryption key distribution method comprising: encrypting and transmitting the first shared key through a different route . A quantum cryptography key distribution method used in a quantum cryptography communication system including at least a first communication device, a second communication device, and third and fourth communication devices,
A procedure for generating first and second shared keys between the first communication device and the second communication device using weak light according to a quantum cryptography protocol;
A procedure for generating a third shared key between the second communication device and the third communication device using weak light by the quantum cryptography protocol;
A procedure for generating a fourth shared key between the second communication device and the fourth communication device using weak light by the quantum cryptography protocol;
A step of encrypting the first shared key itself using the third shared key in the second communication device and then transmitting the encrypted key to the third communication device;
A procedure of transmitting the second shared key itself after encrypting the second shared key itself using the fourth shared key in the second communication device;
A procedure in which the third communication device decrypts the first shared key encrypted by the second communication device using the third shared key;
The fourth communication device decrypting the second shared key encrypted by the second communication device using the fourth shared key;
Plain text transmitted from the first communication apparatus to the third communication apparatus or plain text transmitted from the third communication apparatus to the first communication apparatus using the first shared key in a shared key system. A procedure of encrypting and transmitting through a different route from the transmission of the first shared key ;
Plain text transmitted from the first communication apparatus to the fourth communication apparatus or plain text transmitted from the fourth communication apparatus to the first communication apparatus using the second shared key in a shared key system. A quantum encryption key distribution method comprising: encrypting and transmitting the second shared key through a different route . A quantum key distribution method used in a quantum cryptography communication system comprising at least a first communication device and second and third communication devices,
Generating a first shared key between the first communication device and the second communication device using weak light by a quantum cryptography protocol;
Generating a second shared key between the first communication device and the third communication device using weak light by the quantum cryptography protocol;
A procedure for generating a third shared key using weak light by the quantum cryptography protocol between the second communication device and the next-stage communication device adjacent to the second communication device;
A procedure for generating a fourth shared key using weak light by the quantum cryptography protocol between the third communication device and the next-stage communication device adjacent to the third communication device;
A procedure in which the second communication device encrypts the first shared key itself using the third shared key and then transmits it to the next-stage communication device adjacent thereto;
A procedure in which the third communication device encrypts the second shared key itself using the fourth shared key and then transmits it to the next-stage communication device adjacent thereto;
A procedure in which the next-stage communication device adjacent to the second communication device decrypts the first shared key encrypted by the second communication device using the third shared key;
A next-stage communication device adjacent to the third communication device decrypts the second shared key encrypted by the third communication device using the fourth shared key;
Plain text transmitted from the first communication device to the next-stage communication device adjacent to the second communication device, or next-stage communication device adjacent to the second communication device transmitted to the first communication device. A procedure of encrypting plaintext using the first shared key by a shared key method and transmitting the plaintext through a path different from the transmission of the first shared key ;
Plain text transmitted from the first communication device to the next-stage communication device adjacent to the third communication device, or next-stage communication device adjacent to the third communication device transmitted to the first communication device. A quantum encryption key distribution method comprising: encrypting plaintext using the second shared key by a shared key method and transmitting the plaintext by a different route from the transmission of the second shared key . A communication device that performs quantum cryptography communication,
Means for generating a first shared key using weak light by a quantum cryptography protocol with the first communication device;
Means for receiving a second shared key generated between the first communication device and the second communication device, wherein the first communication device is encrypted and transmitted using the first shared key When,
Means for decrypting the second shared key using the first shared key;
A communication apparatus comprising: means for transmitting and receiving plaintext to and from the second communication apparatus using a path different from the transmission of the second shared key using the second shared key . A communication device that performs quantum cryptography communication,
Means for generating a first shared key using weak light by a quantum cryptography protocol with the first communication device;
The second communication device is encrypted by the first communication device with a second shared key generated using weak light by a quantum cryptography protocol between the first communication device and the second communication device. Means for transmitting / receiving plaintext to / from the second communication device using a path different from the transmission of the first shared key using the first shared key relayed to the communication device. Communication device. An encryption communication method used for a communication device that performs quantum encryption communication,
The communication device is
Generating a first shared key with weak light using a quantum cryptography protocol with the first communication device;
Receiving a second shared key generated between the first communication device and the second communication device , which is transmitted by the first communication device encrypted using the first shared key. When,
Decrypting the second shared key using the first shared key;
And a step of transmitting and receiving plaintext to and from the second communication device using a path different from the transmission of the second shared key using the second shared key. An encryption communication method used for a communication device that performs quantum encryption communication,
The communication device is
Generating a first shared key with weak light using a quantum cryptography protocol with the first communication device;
The second communication device is encrypted by the first communication device with a second shared key generated using weak light by a quantum cryptography protocol between the first communication device and the second communication device. Using the first shared key relayed to the communication device to perform transmission and reception of plaintext with the second communication device through a different path from the transmission of the first shared key. Encryption communication method.

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