JP4684663B2 - Quantum cryptographic communication system and method - Google Patents

Description

  The present invention relates to a quantum cryptography communication system and method that solves a key management problem assumed when quantum cryptography is applied to a large-scale network by setting a key management station.

Conventional quantum cryptography provides unconditional security in terms of computational complexity, but is basically end-to-end communication, and the required classical authentication communication is also performed end-to-end. When it becomes larger, N is the number of entities and N ² authentication secret keys must be managed (key explosion). Further, each entity has to have an expensive quantum transmission device and quantum reception device (see, for example, Non-Patent Document 1).

  Further, as an improvement in which each entity does not need to have an expensive quantum cryptography device, there is a quantum cryptography method in which quantum transmission / reception devices are concentrated in a center, and the center discloses a quantum reception result. In this method, since the quantum communication path penetrates both two entities that perform quantum cryptography communication, the probe light is inserted in the middle of the quantum communication path and transmitted through the target entity, and then the probe light is measured. There is a problem that security is vulnerable to a Trojan horse attack that realizes eavesdropping (see, for example, Patent Document 1).

  When a quantum channel penetrates only one entity against a Trojan horse attack, sufficiently strong coherent light is used as a quantum source, and the entity uses a branching path and a photodetector to scan light before input. A method that monitors partly and uses an attenuator to reduce the light intensity after output to the quantum level, detects a Trojan horse attack when the probe light is sufficiently strong, and attacks when a probe light that is so weak that it cannot be detected Is known to maintain practical security in the sense of invalidation (see, for example, Non-Patent Document 2).

  Also, in the key management system using classical cryptography, there are some known systems that avoid the explosion of the number of key managements, but unlike quantum cryptography, only the computational security can be guaranteed. In particular, a key management method using public key cryptography is known to be easily decipherable if a quantum computer can be used, and security from a long-term viewpoint is weak. On the other hand, in the key management method using the common key cryptosystem, the quantum computer does not extremely reduce the computational security, but the confidentiality of the secret key that can be shared between the entities is However, there is a problem that there is no theory (see, for example, Non-Patent Document 3).

US Pat. No. 5,764,765 Bennett and Brassard, “QUANTUM CRYPTOGRAPHY: PUBLIC KEY DISTRIBUTION AND COIN TOSSING” International Conference on Computers, Systems & Signal Processing Bangalore, India, Dec. 12-14,1984 Gisin, et. Al., “Quantum Cryptography” Review of Modern Physics, 74 pp.189, 2002 Steiner, et. Al., “Kerberos: An Authentication Service for Open Network Systems” Proc. Of the Winter USENIX Conf. Feb. 1988 M. N. Wegman and J. L. Carter, “New Hash Functions and Their Use in Authentication and Set Equality” Journal of Computer and Systems Science 22, pp.265-279, 1981

  Conventional quantum cryptography has a problem that the number of key management explodes when applied to a large-scale network.

  Further, the conventional quantum cryptography has a problem that each entity has to hold an expensive quantum cryptography communication device, and if it is an inexpensive quantum cryptography communication device, it becomes vulnerable to a Trojan horse attack.

  Furthermore, in the key management method based on classical cryptography with a conventional key management station, the security depends on the amount of calculation, and in addition, the confidentiality of the secret key shared between entities with respect to the key management station There was a problem that is not guaranteed.

  The present invention has been made to solve the above-described problems, and a first object thereof is to obtain a quantum cryptography communication system and method capable of suppressing the number of key management to about the number of entities.

  The present invention has been made to solve the above-described problems. The second object of the present invention is to reduce the cost of the quantum cryptography communication device held by each entity and to prevent a Trojan horse attack. A quantum cryptography communication system and method that can guarantee confidentiality are obtained.

  The present invention has been made to solve the above-described problems, and a third object is to provide quantum cryptography communication that can guarantee unconditional safety in terms of computational complexity and confidentiality to a key management station. A system and method is obtained.

The quantum cryptography communication system according to the present invention is a quantum cryptography communication system comprising a single key management station and a plurality of entities as nodes of a network, wherein the key management station and the plurality of entities are capable of quantum cryptography communication. Are connected to each other in a classical communication network that can be classically communicated with each other by a simple quantum communication channel, and authenticate classical communication in quantum cryptography communication between arbitrary entities via the key management station. A quantum cryptography communication system, wherein the key management station performs quantum cryptography communication, and executes first random number generation means for generating a first random number, presence / absence of an eavesdropper, and key sharing A first data processing means; a first quantum transmitting means for generating and modulating a quantum according to the generated first random number; and transmitting the quantum to the quantum communication channel; and the first quantum processing means according to the generated first random number. First quantum receiving means for measuring the quantum transmitted to the child communication path, and for performing classical authentication communication, generating initial keys for authentication of all entities, and ensuring confidentiality A key managing means for delivering to each entity by a method; a first authenticator generating means for generating an authenticator; a first authenticator checking means for checking an authenticator; and classical communication via the classical communication network. A first classical communication means for performing the quantum cryptography communication, and the entity performs second random number generation means for generating a second random number, presence / absence of an eavesdropper, and key sharing. Second data processing means to execute; second quantum transmission means for generating and modulating quantum according to the generated second random number; and transmitting the quantum communication path to the quantum communication path; and the quantum communication path according to the generated second random number Second to measure the quantum transmitted to A quantum receiving means for performing classical authentication communication, a secret key holding means for holding the delivered initial key for authentication, a second authenticator generating means for generating an authenticator, and an authenticator And a second authenticator verification means for verifying and a second classical communication means for executing classical communication via the classical communication network .

  In the quantum cryptography communication system according to the present invention, the number of key management can be suppressed to the number of entities, the quantum cryptography communication device held by each entity can be made inexpensive, and against a Trojan horse attack Thus, it is possible to guarantee the secrecy, and further, it is possible to guarantee the unconditional safety in terms of calculation amount and the secrecy of the key management station.

Embodiment 1 FIG.
A quantum cryptography communication system according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a configuration of a quantum cryptography communication system according to Embodiment 1 of the present invention. In addition, in each figure, the same code | symbol shows the same or equivalent part.

  In FIG. 1, the quantum cryptography communication system according to the first embodiment is provided with a key management station 1, a plurality of entities 2 (A to D), and a classical communication network 3.

  A node of the network of this quantum cryptography communication system is composed of a single key management station 1 and a plurality of entities 2, and each entity 2 and the key management station 1 are in a one-to-one relationship with a quantum communication path capable of quantum cryptography communication. It is connected. It is also connected to the classical communication network 3.

  FIG. 2 is a diagram showing the configuration of the key management station of the quantum cryptography communication system according to Embodiment 1 of the present invention. In FIG. 2, the key management station (KDC) 1 includes a random number generation unit 11, a data processing unit 12, a quantum transmission unit 13, and a quantum reception unit 14 for performing quantum cryptography communication. It has key management means 15, authenticator generation means 16, authenticator verification means 17, and classical communication means 18 for performing classical authentication communication.

  FIG. 3 is a diagram showing a configuration of entities of the quantum cryptography communication system according to Embodiment 1 of the present invention. In FIG. 3, each entity 2 includes a random number generation unit 21, a data processing unit 22, a quantum transmission unit 23, and a quantum reception unit 24 for performing quantum cryptography communication, and performs classical authentication communication. It has a secret key holding means 25, an authenticator generating means 26, an authenticator collating means 27, and a classical communication means 28 for performing.

  Next, the operation of the quantum cryptography communication system according to the first embodiment will be described with reference to the drawings.

  FIG. 4 is a flowchart showing an operation from initial setting of the quantum cryptography communication system according to Embodiment 1 of the present invention to sharing of a secret key between arbitrary entities A and B. In FIG. 4, the key management station (KDC) is a “trusted” third-party organization, but the secrecy regarding the shared key between ABs also holds for KDC.

  FIG. 5 is a diagram showing an initial setting state of the quantum cryptography communication system according to Embodiment 1 of the present invention. 6 and 7 are diagrams showing a state of communication 1 (first communication) of the quantum cryptography communication system according to Embodiment 1 of the present invention.

  First, as shown in FIG. 5, the key management station 1 generates the authentication initial keys KA0, KB0, KC0, KD0 for all the entities 2 by the key management means 15, and uses a method in which confidentiality is guaranteed. Deliver to 2. The key management means 15 holds the initial key for authentication so as to know which entity 2 corresponds to which entity 2. In each entity 2, the secret key holding means 25 holds the delivered initial key for authentication.

  When an event for sharing a secret key between an arbitrary entity A and an arbitrary entity B is started, as shown in FIGS. 6 and 7, the entity A and the entity B are independently communicated with the key management station 1. Execute quantum cryptography and expand the private key.

  Here, the key expansion is to share a longer key by consuming the initial key for authentication shared in advance. For example, in the quantum cryptography communication between the entity A and the key management station 1, the entity A and the key management station 1 independently generate random numbers using the random number generation units 21 and 11, and the entity A follows the generated random numbers. After generating and modulating the quantum using the quantum transmission means 23, the quantum is transmitted to the key management station 1 through the quantum communication path. The key management station 1 adjusts the quantum receiving means 14 according to the generated random number, and measures the transmitted quantum.

  After this quantum transmission, the entity A and the key management station 1 use the classical communication network 3 to exchange information such as some random number information and error correction information for completing the quantum cryptography communication. In the process of exchanging information, the entity A and the key management station 1 execute the presence / absence of an eavesdropper and the key sharing by using the respective data processing means 22 and 12. In the classical communication, classical communication means 28 and 18 included in the entity A and the key management station 1 are executed via the classical communication network 3. The authentication of this communication is executed by the authenticator generation means 26 and 16 and the authenticator verification means 27 and 17 included in both of them using the authentication initial key KA0. For example, using a Wegman Carter authenticator using a disposable key (Non-Patent Document 4, FIG. 8), the process is performed as shown in FIGS.

  The used initial key for authentication is discarded. A part of the generated shared key is used for updating the initial key for authentication, and the secret key holding unit 25 of the entity A and the key management unit 15 of the key management station 1 hold the new initial key for authentication KA0. The remaining shared key is held by the secret key holding unit 25 of the entity A and the key management unit 15 of the key management station 1 as the work key WKA of the event.

  FIG. 9 is a diagram showing a state of communication 2 (second communication) of the quantum cryptography communication system according to Embodiment 1 of the present invention. FIG. 10 is a diagram showing a state of communication 3 (third communication) of the quantum cryptography communication system according to Embodiment 1 of the present invention. FIG. 11 is a diagram showing a state of authentication of classical communication of the quantum cryptography communication system according to Embodiment 1 of the present invention.

  Next, as shown in FIG. 9, entity A and entity B perform quantum communication using the mutually connected quantum communication paths. For example, the entity A and the entity B independently generate random numbers using the respective random number generation means 21, and the entity A generates and modulates the quantum using the quantum transmission means 23 according to the generated random number, and then performs quantum communication. Transmit to entity B over the path. The entity B adjusts the quantum receiving means 24 according to the generated random number and measures the transmitted quantum.

  Finally, as shown in FIG. 10, in order to complete the quantum cryptography communication associated with the quantum transmission using the classical communication network 3, the entity A and the entity B have some random number information, error correction information, etc. Information exchange is performed via the key management station 1. In the process of exchanging information, the entity A and the entity B use the respective data processing means 22 to execute presence / absence of an eavesdropper and key sharing.

  As shown in FIG. 11, the authentication of the classical communication generates an authenticator between the entity A and the key management station 1 by using a part of the work key WKA shared by the entity A and the key management station 1 in the previous communication. When the authentication is performed by the means 26 and 16 and the authenticator verification means 27 and 17, and the key management station 1 succeeds in the authentication with the entity A, the key management station 1 uses a part of the work key WKB shared in the previous communication with the entity B, The authenticator generation means 16 and 26 and the authenticator verification means 17 and 27 authenticate between the key management station 1 and the entity B. If the entity B succeeds in authentication with the key management station 1, authentication communication to the entity A is also executed via the key management station 1 in the same procedure. At this time, the key generated between the entities A and B is shared as KAB.

  As described above, since classical communication authentication in quantum cryptography communication between arbitrary entities is performed via the key management station 1, each entity 2 has only one key with the key management station 1 as an initial key for authentication. And the total number of keys to be managed in the entire system is about the total number of entities 2 participating in the system. Compared with the method in which the key management station 1 manages keys using classical cryptography, since key distribution is performed using quantum cryptography, unconditional security in terms of computational complexity is ensured. It is possible to realize much stronger security than a method using public key cryptography as a classical cipher to be decrypted. On the other hand, in the method using the common key encryption as the classical encryption, there is no secrecy to the key management station 1 of the secret key shared between arbitrary entities, but in this method, it is finally shared between the entities. Since no secret information about the secret key is transmitted to the key management station 1, the confidentiality is also guaranteed to the key management station 1. For this reason, the reliability required for the key management station 1 is relaxed, and system construction is facilitated.

Embodiment 2. FIG.
A quantum cryptography communication system according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 12 is a diagram showing a configuration of a quantum cryptography communication system according to Embodiment 2 of the present invention.

  In the first embodiment, each entity 2 and the key management station 1 are connected to each other via a one-to-one quantum communication path, and all the entities 2 have the quantum transmission unit 23 and the quantum reception unit 24, respectively. However, in the second embodiment, there is one quantum communication channel in the entire system, both ends thereof are connected to the key management station 1, and each entity 2 is penetrated by this quantum communication channel. Each entity 2 except for the key management station 1 may have a quantum modulation unit 29d instead of the quantum transmission unit 23 and the quantum reception unit 24.

  In FIG. 12, the quantum cryptography communication system according to the second embodiment includes a key management station 1, a plurality of entities 2 (A to D), and a classical communication network 3.

  A node of the network of this quantum cryptography communication system is composed of a plurality of entities 2 and a single key management station 1, and the quantum communication path from the key management station 1 has a loop form that returns to the key management station 1 again. I'm taking it. Each entity 2 is arranged one-dimensionally on this quantum communication path. The key management station 1 and each entity 2 are also connected to the classical communication network 3.

  FIG. 13 is a diagram showing a configuration of entities of the quantum cryptography communication system according to Embodiment 2 of the present invention. In FIG. 13, each entity 2 has a random number generation means 21, a data processing means 22, and a quantum modulation means 29d for performing quantum cryptography communication, and a secret key for performing classical authentication communication. The holding unit 25, the authenticator generating unit 26, the authenticator collating unit 27, and the classical communication unit 28 are included. Further, in preparation for a Trojan horse attack in which an eavesdropper enters probe light into each entity and tries to steal information directly from the quantum modulation means 29d, the intensity of the optical signal flowing through the quantum communication path is monitored. In order to detect a horse attack, a beam splitter 29a that guides a part of the optical signal to the branching optical path, a monitoring light detection means 29b that measures the intensity of the optical signal guided to the branching optical path, and a quantum communication path When the optical signal passes through the inside of the entity and is output, the optical signal has a variable attenuator 29c whose light intensity is reduced to the quantum level.

  As shown in FIG. 2, the key management station includes random number generation means 11, data processing means 12, quantum transmission means 13, and quantum reception means 14 for performing quantum cryptography communication. It has key management means 15, authenticator generation means 16, authenticator verification means 17, and classical communication means 18 for performing communication.

  Next, the operation of the quantum cryptography communication system according to the second embodiment will be described with reference to the drawings.

  FIG. 14 is a flowchart showing operations from initial setting of the quantum cryptography communication system according to Embodiment 2 of the present invention to sharing of a secret key between arbitrary entities A and B. In FIG. 14, the key management station (KDC) is a “trusted” third-party organization, but the confidentiality regarding the shared key between ABs is also established for KDC.

  FIG.15 and FIG.16 is a figure which shows the mode of the communication 1 (1st communication) of the quantum cryptography communication system which concerns on Embodiment 2 of this invention. FIG. 17 is a diagram showing a state of communication 2 (second communication) of the quantum cryptography communication system according to Embodiment 2 of the present invention.

  First, as shown in FIG. 5, the key management station 1 generates the authentication initial keys KA0, KB0, KC0, KD0 for all the entities 2 by the key management means 15, and uses a method in which confidentiality is guaranteed. Deliver to 2. The key management means 15 holds the initial key for authentication so as to know which entity 2 corresponds to which entity 2. In each entity 2, the secret key holding means 25 holds the delivered initial key for authentication.

  When an event for sharing a secret key between an arbitrary entity A and an arbitrary entity B is started, first, as communication 1 (first communication), as shown in FIGS. 15 and 16, entity A and entity B Performs quantum cryptography communication with the key management station 1 independently to extend the secret key.

  Here, the key expansion is to share a longer key by consuming the initial key for authentication shared in advance. For example, in the quantum cryptography communication between the entity A and the key management station 1, the entity A and the key management station 1 independently generate random numbers using the random number generation means 21 and 11, respectively. Accordingly, the quantum modulation unit 29d is used to modulate the quantum generated by the quantum transmission unit 13 of the key management station 1 and transmitted through the quantum communication path, and then transmits the modulated quantum to the key management station 1 through the quantum communication path. The key management station 1 adjusts the quantum receiving means 14 according to the generated random number, and measures the transmitted quantum.

  After this quantum transmission, the entity A and the key management station 1 use the classical communication network 3 to exchange information such as some random number information and error correction information for completing the quantum cryptography communication. In the process of exchanging information, the entity A and the key management station 1 execute the presence / absence of an eavesdropper and the key sharing using the respective data processing means 22 and 12. In the classical communication, classical communication means 28 and 18 included in the entity A and the key management station 1 are executed via the classical communication network 3. The authentication of this communication is executed by the authenticator generation means 26 and 16 and the authenticator verification means 27 and 17 included in both of them using the authentication initial key KA0. For example, this is performed using a Wegman Carter authenticator using a disposable key.

  The used initial key for authentication is discarded. A part of the generated shared key is used for updating the initial key for authentication, and the secret key holding unit 25 of the entity A and the key management unit 15 of the key management station 1 hold the new initial key for authentication KA0. The remaining shared key is held by the secret key holding means 25 of the entity A and the key management means 15 of the key management station 1 as the work key WKA of the event.

  Note that the quantum signal output from the key management station 1 may be an optical signal having sufficient intensity, and is guided to the partial branching optical path by the beam splitter 29a inside the entity A, and the light is detected by the monitoring light detection means 29b. The intensity is monitored. Further, the optical signal guided to the quantum modulation means 29d is attenuated by the variable attenuator 29c to the light intensity having only one photon in the optical signal. Therefore, the optical signal output from the entity A has a light intensity of a quantum level.

  Therefore, when a Trojan horse attack is performed, the presence or absence of the probe light is detected by the monitoring light detection means 29b, and the attack can be detected. Further, since the variable attenuator 29c attenuates the probe light to an extent that is sufficient, the attacker cannot obtain the internal information of the quantum modulation means 29d.

  Next, as communication 2 (second communication), as shown in FIG. 17, entity A and entity B perform quantum communication using a quantum communication path laid in a loop form from key management station 1. Note that the entity on the upstream side of the quantum channel is A, and the entity on the downstream side is B. For example, the entity A and the entity B independently generate random numbers using the respective random number generation means 21, and the entity A is generated by the quantum transmission means 13 of the key management station 1 according to the generated random numbers, and the quantum communication channel The quantum that has been transmitted is modulated using the quantum modulation means 29d, and then the quantum is transmitted to the entity B. The entity B modulates the quantum transmitted from the entity A using the quantum modulation means 29d according to the generated random number, and transmits the modulated quantum to the key management station 1. The key management station 1 measures the quantum transmitted by the quantum receiving means 14.

  The quantum signal output from the key management station 1 may be an optical signal having sufficient strength. A beam splitter 29a located inside the entity A guides the light to the first branch optical path, and its light intensity is monitored by the monitoring light detection means 29b. Further, the optical signal guided to the quantum modulation means 29d is attenuated by the variable attenuator 29c to the light intensity having only one photon in the optical signal. Therefore, the optical signal output from the entity A has a light intensity of a quantum level. Similarly, in the entity B, the light is guided to the partial branching optical path by the beam splitter 29a inside the entity B, and the light intensity is monitored by the monitoring light detection means 29b. However, since the optical signal input to the entity B is already at the quantum level, the variable attenuator 29c of the entity B is opened.

  For this reason, the internal information of the quantum modulation means 29d of the entity A does not leak against a Trojan horse attack, but the internal information of the quantum modulation means 29d of the entity B is slightly weak with respect to leakage countermeasures. Communication 5 (fifth communication) described below is a countermeasure against this.

  FIG. 18 is a diagram showing states of communication 3 (third communication) to communication 5 (fifth communication) of the quantum cryptography communication system according to the second embodiment of the present invention. FIG. 19 is a diagram showing the public detection BB84 protocol (phase modulation) of the quantum cryptography communication system according to the second embodiment of the present invention. FIG. 20 is a diagram showing a state of communication 5 (fifth communication) of the quantum cryptography communication system according to Embodiment 2 of the present invention.

  As communication 3 (third communication), as shown in FIG. 18, the key management station 1 sends the measurement results of the quantum reception means 14 obtained in communication 2 (second communication) to the entity A and the entity B respectively. The communication means 28 publishes using the classical communication network 3.

  At this time, the authentication of the classical communication is performed by using a part of the work keys WKA and WKB shared by the entities A and B and the key management station 1 in the previous communication in the communication 1 (first communication). , B and the key management station 1 are authenticated by authenticator generation means 26 and 16 and authenticator verification means 27 and 17.

  As communication 4 (fourth communication), as shown in FIG. 18, in order to complete quantum cryptography communication associated with quantum transmission in communication 2 (second communication) using classical communication network 3, entity A and entity B performs information exchange such as partial random number information and error correction information through the key management station 1. In the process of exchanging information, the entity A and the entity B use the respective data processing means 22 to execute presence / absence of an eavesdropper and key sharing. This communication protocol is similar to the protocol described in Patent Document 1, for example.

  In particular, FIG. 19 shows that key sharing can be realized by exchanging a part of random number information between entity A and entity B. Here, the entities A and B apply phase modulation to one quantum pulse using two random numbers ((a1, a0) and (b1, b0)) in communication 2 (second communication), respectively. . The result of measuring this photon pulse by the key receiving station 14 by the key management station 1 is 1 bit (d). Since the key management station 1 publishes the measurement result d to the entities A and B by communication 3 (third communication), in communication 4 (fourth communication), the entity A has higher-order bits a1 and By exchanging the higher-order bit b1 of the random number, the entities A and B can know the match / mismatch of the higher-order bits of the random number. If they match, the entity A uses the 1-bit secret key k as Entity B can secretly share k = b0 xor d xor b1 with k = a0 as the secret key k. Here, since each lower 1 bit is secret information known only to each entity, confidentiality is guaranteed.

  As shown in FIG. 11, the authentication of the classical communication generates an authenticator between the entity A and the key management station 1 by using a part of the work key WKA shared by the entity A and the key management station 1 in the previous communication. If the authentication is performed by the means 26 and 16 and the authenticator verification means 27 and 17, and the key management station 1 succeeds in the authentication with the entity A, the key management station 1 uses a part of the work key WKB shared in the previous communication with the entity B. The authenticator generation means 16 and 26 and the authenticator verification means 17 and 27 authenticate between the key management station 1 and the entity B. If the entity B succeeds in authentication with the key management station 1, authentication communication to the entity A is also executed via the key management station 1 in the same procedure.

  In this way, the secret key generated between the entities A and B is shared as KAB. However, since the above-mentioned communication 2 (second communication) is vulnerable to the Trojan horse attack, this secret key KAB has the following communication 5 to obtain a secret key with guaranteed security. (Fifth communication) is performed.

  As communication 5 (fifth communication), as shown in FIG. 18, the classical communication network 3 is used to perform double encryption communication from the entity A to the key management station 1 and from the key management station 1 to the entity B.

For example, as shown in FIG. 20, the entity A newly generates a random number R using the random number generation means 21. The entity A encrypts the random number R by using the secret key KAB shared with the entity B obtained in the communication 4 (fourth communication), and then uses the key management station in the communication 1 (first communication). 1 is encrypted using the rest of the work key WKA shared with 1. The double-encrypted ciphertext C _{A, KDC} , for example, C _{A, KDC} = R xor KAB xor WKA passes through the classical communication network 3 to the key management station 1 using the respective classical communication means 28, 18. Is transmitted. The key management station 1 decrypts the received ciphertexts _CA and _KDC with the rest of the work key WKA shared with the entity A, and then the work key WKB shared with the entity B in the communication 1 (first communication). Encrypt using the rest. The ciphertext C _{KDC, B} , for example, C _{KDC, B} = C _{A, KDC} xor WKA xor WKB = R xor KAB xor WKB is transferred to the entity B by using the respective classical communication means 18 and 28. Transmitted through. The entity B decrypts the received ciphertext C _{KDC, B} with the rest of the work key WKB shared with the key management station 1 and then encrypts it using the secret key KAB shared with the entity A.

  Thus, the random number R shared secretly between the entities A and B is a secret key finally shared between the entities A and B.

  For this reason, even if the secret key KAB is leaked to the eavesdropper by a Trojan horse attack, the final secret key to the eavesdropper is obtained by encrypting it with the work keys WKA and WKB that are safe against the Trojan attack. There is no leakage of R. In addition, since the confidentiality of the secret key KAB is guaranteed with respect to the key management station 1, there is no possibility of R leaking to the key management station 1 during the R transmission.

  As described above, as in the first embodiment, authentication of classical communication in quantum cryptography communication between arbitrary entities is performed via the key management station 1, so that each entity 2 has a key as an initial key for authentication. It is sufficient to hold only one key with the management station 1, and the total number of keys to be managed in the entire system is about the total number of entities 2 participating in the system. Compared with the method in which the key management station 1 manages keys using classical cryptography, since key distribution is performed using quantum cryptography, unconditional security in terms of computational complexity is ensured. It is possible to realize much stronger security than a method using public key cryptography as a classical cipher to be decrypted. Moreover, in the method using the common key encryption as the classical encryption, there is no secrecy to the key management station 1 of the secret key shared between arbitrary entities, but in this method, it is finally shared between the entities. Since the secrecy of the secret key is guaranteed to the key management station 1 as well, the reliability required for the key management station 1 is relaxed, and the system construction is facilitated.

  In the second embodiment, the expensive quantum transmitting means 13 and the quantum receiving means 14 are integrated into the key management station 1, and each entity 2 only needs to be an inexpensive quantum modulation means 29d, and cost reduction can be realized. Moreover, the vulnerability to the Trojan horse attack that the method of concentrating expensive devices in such a key management station 1 has to be improved, and a quantum cryptography communication system having strong security can be provided. .

Embodiment 3 FIG.
A quantum cryptography communication system according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 21 is a diagram showing a configuration of a quantum cryptography communication system according to Embodiment 3 of the present invention.

  In the second embodiment, the quantum communication path is in the form of a loop. In the third embodiment, the key management station 1 is installed at one end and the Faraday mirror at the other end with respect to the quantum communication path. In this way, it has a bus-type configuration provided with a mirror 4 that reflects quantum. Each entity 2 is arranged on this quantum communication path.

  In FIG. 21, the quantum cryptography communication system according to Embodiment 3 is provided with a key management station 1, a plurality of entities 2 (A to D), a classical communication network 3, and a mirror 4.

  The configurations of the key management station 1 and each entity 2 are the same as those in the second embodiment. Further, each operation is the same as that of the second embodiment because the quantum signal emitted from the key management station 1 is reflected by the Faraday mirror 4 at the other end and returns to the key management station 1.

It is a figure which shows the structure of the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the key management station of the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the entity of the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement from the initial setting of the quantum cryptography communication system which concerns on Embodiment 1 of this invention to sharing a secret key between arbitrary entities A and B. It is a figure which shows the mode of the initial setting of the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a figure which shows the mode of the communication 1 (1st communication) of the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a figure which shows the mode of the communication 1 (1st communication) of the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a figure which shows the authenticator of Wegman Carter in the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a figure which shows the mode of the communication 2 (2nd communication) of the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a figure which shows the mode of the communication 3 (3rd communication) of the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a figure which shows the mode of the authentication of the classical communication of the quantum cryptography communication system which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the quantum cryptography communication system which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the entity of the quantum cryptography communication system which concerns on Embodiment 2 of this invention. It is a flowchart which shows operation | movement from the initial setting of the quantum cryptography communication system which concerns on Embodiment 2 of this invention to sharing a secret key between arbitrary entities A and B. It is a figure which shows the mode of the communication 1 (1st communication) of the quantum cryptography communication system which concerns on Embodiment 2 of this invention. It is a figure which shows the mode of the communication 1 (1st communication) of the quantum cryptography communication system which concerns on Embodiment 2 of this invention. It is a figure which shows the mode of the communication 2 (2nd communication) of the quantum cryptography communication system which concerns on Embodiment 2 of this invention. It is a figure which shows the mode of communication 3 (3rd communication)-5 of the quantum cryptography communication system which concerns on Embodiment 2 of this invention. It is a figure which shows the public detection BB84 protocol (phase modulation) of the quantum cryptography communication system which concerns on Embodiment 2 of this invention. It is a figure which shows the mode of the communication 5 (5th communication) of the quantum cryptography communication system which concerns on Embodiment 2 of this invention. It is a figure which shows the structure of the quantum cryptography communication system which concerns on Embodiment 3 of this invention.

Explanation of symbols

  1 Key management station, 2 entities, 3 classical communication network, 4 mirror, 11 random number generation means, 12 data processing means, 13 quantum transmission means, 14 quantum reception means, 15 key management means, 16 authenticator generation means, 17 authenticator Verification means, 18 Classical communication means, 21 Random number generation means, 22 Data processing means, 23 Quantum transmission means, 24 Quantum reception means, 25 Secret key holding means, 26 Authentication code generation means, 27 Authentication code verification means, 28 Classic communication means , 29a Beam splitter, 29b Monitor light detection means, 29c Variable attenuator, 29d Quantum modulation means.

Claims (6)

A quantum cryptography communication system comprising a single key management station and a plurality of entities as nodes of a network,
The key management station and the plurality of entities are connected to each other one-to-one by a quantum communication path capable of quantum cryptography communication and connected to a classical communication network capable of classical communication,
A quantum cryptography communication system for authenticating classical communication in quantum cryptography communication between arbitrary entities via the key management station,
The key management station performs quantum cryptography communication, and generates a first random number generating unit that generates a first random number, a first data processing unit that executes presence / absence of an eavesdropper and key sharing, First quantum transmitting means for generating and modulating quantum according to the generated first random number and transmitting the quantum to the quantum channel; and first measuring the quantum transmitted to the quantum channel according to the generated first random number A key management means for generating classical initial authentication keys for all entities and delivering them to each entity in a manner in which confidentiality is guaranteed; A first authenticator generating means for generating a first authenticator, a first authenticator checking means for checking an authenticator, and a first classical communication means for executing classical communication via the classical communication network,
The entity is for performing quantum cryptography communication, a second random number generating means for generating a second random number, a second data processing means for executing presence / absence of an eavesdropper and key sharing, A second quantum transmitter for generating and modulating a quantum according to a random number of 2 and transmitting the quantum to the quantum communication channel; and a second quantum receiver for measuring the quantum transmitted to the quantum channel according to the generated second random number A secret key holding means for holding a delivered initial key for authentication, a second authenticator generating means for generating an authenticator, and a verification of the authenticator quantum cryptographic communication system that, comprising a second authenticator verification means, and a second classical communication means for performing the classical communication via the classical communication network. In a quantum cryptography communication system in which a key management station and a plurality of entities are connected to each other one-to-one by a quantum communication path capable of quantum cryptography communication and connected to a classical communication network capable of classical communication.
An initial setting step in which the key management station distributes an initial key for authentication secretly shared with each entity to each entity;
When any first and second entities attempt to share a secret key in quantum cryptography communication, the first and second entities independently perform quantum cryptography communication with the key management station and The first and second entities and the key management station discard the initial key for authentication used in the quantum cryptography communication at this time, and consume a part of the private key whose key has been extended. A first communication step for updating as a secret key for authentication in preparation for quantum cryptography communication with the next key management station;
A second communication step of performing quantum transmission for quantum cryptography communication using a quantum communication path connected between the first and second entities;
The first and second entities transmit classical information for completing quantum cryptography communication using the transmitted quanta via the key management station, and at this time, each entity in the first communication step. And a third communication step of performing authentication communication between each entity and the key management station by consuming the secret key whose key is extended by the key management station. A quantum cryptography communication system comprising a single key management station and a plurality of entities as nodes of a network,
The key management station and the plurality of entities are connected in a loop through a single quantum communication path capable of quantum cryptography communication so that the key management station is a starting point and an end point, and penetrates the plurality of entities, and classical communication Connected to each possible classical communication network,
A quantum cryptography communication system for authenticating classical communication in quantum cryptography communication between arbitrary entities via the key management station,
The key management station performs quantum cryptography communication, and generates a first random number generating unit that generates a first random number, a first data processing unit that executes presence / absence of an eavesdropper and key sharing, Quantum transmitting means for generating and modulating quantum according to the generated first random number and transmitting the quantum to the quantum communication path, and quantum receiving means for measuring the quantum transmitted to the quantum communication path according to the generated first random number In addition, for performing classical authentication communication, a first key for generating an authentication initial key for all entities and delivering to each entity in a method in which confidentiality is ensured, and a first authenticator An authenticator generating means, a first authenticator checking means for checking an authenticator, and a first classical communication means for executing classical communication via the classical communication network,
The entity is for performing quantum cryptography communication, a second random number generating means for generating a second random number, a second data processing means for executing presence / absence of an eavesdropper and key sharing, A quantum modulation means for modulating the quantum transmitted through the quantum communication path in accordance with a random number of 2, and a variable for reducing the signal light incident on the quantum modulation means to a quantum level after transmission to the quantum communication path An attenuator, a beam splitter for partially branching the signal light from the quantum communication path, and a monitoring light detecting means for monitoring the branched signal light, and for performing classical authentication communication, wherein the delivered authentication A secret key holding means for holding an initial key for use, a second authenticator generating means for generating an authenticator, a second authenticator checking means for checking the authenticator, and classical communication via the classic communication network. Execution Quantum cryptographic communication system that, comprising a second classical communication unit that. A key management station and a plurality of entities are connected in a loop form through a single quantum communication channel capable of quantum cryptography communication so that the key management station is a starting point and an ending point and penetrate the plurality of entities, and classical communication is possible. In the quantum cryptography communication system connected to the classical communication network,
An initial setting step in which the key management station distributes an initial key for authentication secretly shared with each entity to each entity;
When any first and second entities attempt to share a secret key in quantum cryptography communication, the first and second entities independently perform quantum cryptography communication with the key management station and The first and second entities and the key management station discard the initial key for authentication used in the quantum cryptography communication at this time, and consume a part of the private key whose key has been extended. A first communication step for updating as a secret key for authentication in preparation for quantum cryptography communication with the next key management station;
The first and second entities are transmitted independently from the key management station, pass through a quantum communication path that passes through each entity, and are independently received according to a random number generated by each of the quanta received by the key management station. A second communication step of applying random quantum modulation to
The key management station, a third communication step of publishing the quantum reception result to the first and second entities by classical communication;
The first and second entities transmit classical information for completing quantum cryptography communication using the transmitted quanta via the key management station, and at this time, each entity in the first communication step. And a fourth communication step of performing authentication communication between each entity and the key management station by consuming the secret key whose key is extended by the key management station, and the first entity generates a random number, The rest of the secret key that has been key-extended with the key management station in the communication step is consumed and encrypted with a one-time pad, and this ciphertext is generated in the second to fourth communication steps. The private key between the first and second entities is consumed and encrypted with a one-time pad and transmitted to the key management station using the classical communication network;
The key management station consumes the remainder of the private key that has been key-extended with the first entity in the first communication step, decrypts the one-time pad, and in the first communication step Expend the private key that has been key-extended with the second entity, encrypt it with a one-time pad, and send it to the second entity using the classical communication network,
The second entity consumes the rest of the secret key key-extended with the key management station in the first communication step, decrypts the one-time pad, and performs the second to fourth communication steps. A random key generated by the first entity is shared as a final secret key by deciphering the one-time pad by consuming the secret key between the first and second entities generated in step 5 A quantum cryptography communication method comprising: a communication step. A quantum cryptography communication system comprising a single key management station and a plurality of entities as nodes of a network,
The key management station and the plurality of entities are arranged in a bus type with one quantum communication path capable of quantum cryptography communication, and the key management station is installed at one end and a mirror that reflects the quantum is installed at the other end. Connected through the plurality of installed entities and connected to a classical communication network capable of classical communication,
A quantum cryptography communication system for authenticating classical communication in quantum cryptography communication between arbitrary entities via the key management station,
The key management station performs quantum cryptography communication, and generates a first random number generating unit that generates a first random number, a first data processing unit that executes presence / absence of an eavesdropper and key sharing, Quantum transmitting means for generating and modulating quantum according to the generated first random number and transmitting the quantum to the quantum communication path, and quantum receiving means for measuring the quantum transmitted to the quantum communication path according to the generated first random number In addition, for performing classical authentication communication, a first key for generating an authentication initial key for all entities and delivering to each entity in a method in which confidentiality is ensured, and a first authenticator An authenticator generating means, a first authenticator checking means for checking an authenticator, and a first classical communication means for executing classical communication via the classical communication network,
The entity is for performing quantum cryptography communication, a second random number generating means for generating a second random number, a second data processing means for executing presence / absence of an eavesdropper and key sharing, A quantum modulation means for modulating the quantum transmitted through the quantum communication path in accordance with a random number of 2, and a variable for reducing the signal light incident on the quantum modulation means to a quantum level after transmission to the quantum communication path An attenuator, a beam splitter for partially branching the signal light from the quantum communication path, and a monitoring light detecting means for monitoring the branched signal light, and for performing classical authentication communication, wherein the delivered authentication A secret key holding means for holding an initial key for use, a second authenticator generating means for generating an authenticator, a second authenticator checking means for checking the authenticator, and classical communication via the classic communication network. Execution Quantum cryptographic communication system that, comprising a second classical communication unit that. A key management station and a plurality of entities are installed between the two, with the key management station installed at one end in a bus form and a mirror reflecting the quantum at the other end by a single quantum communication channel capable of quantum cryptography communication. In the quantum cryptography communication system connected to penetrate through the plurality of entities and connected to the classical communication network capable of classical communication,
An initial setting step in which the key management station distributes an initial key for authentication secretly shared with each entity to each entity;
When any first and second entities attempt to share a secret key in quantum cryptography communication, the first and second entities independently perform quantum cryptography communication with the key management station and The first and second entities and the key management station discard the initial key for authentication used in the quantum cryptography communication at this time, and consume a part of the private key whose key has been extended. A first communication step for updating as a secret key for authentication in preparation for quantum cryptography communication with the next key management station;
The first and second entities are transmitted independently from the key management station, pass through a quantum communication path that passes through each entity, and are independently received according to a random number generated by each of the quanta received by the key management station. A second communication step of applying random quantum modulation to
The key management station, a third communication step of publishing the quantum reception result to the first and second entities by classical communication;
The first and second entities transmit classical information for completing quantum cryptography communication using the transmitted quanta via the key management station, and at this time, each entity in the first communication step. And a fourth communication step of performing authentication communication between each entity and the key management station by consuming the secret key whose key is extended by the key management station, and the first entity generates a random number, The rest of the secret key that has been key-extended with the key management station in the communication step is consumed and encrypted with a one-time pad, and this ciphertext is generated in the second to fourth communication steps. The private key between the first and second entities is consumed and encrypted with a one-time pad and transmitted to the key management station using the classical communication network;
The key management station consumes the remainder of the private key that has been key-extended with the first entity in the first communication step, decrypts the one-time pad, and in the first communication step Expend the private key that has been key-extended with the second entity, encrypt it with a one-time pad, and send it to the second entity using the classical communication network,
The second entity consumes the rest of the secret key key-extended with the key management station in the first communication step, decrypts the one-time pad, and performs the second to fourth communication steps. A random key generated by the first entity is shared as a final secret key by deciphering the one-time pad by consuming the secret key between the first and second entities generated in step 5 A quantum cryptography communication method comprising: a communication step.

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