JP6139803B2 - COMMUNICATION CONTROL DEVICE, COMMUNICATION DEVICE, AND PROGRAM - Google Patents

Description

  Embodiments described herein relate generally to a communication control device, a communication device, and a program.

  A technique for managing devices in groups by distributing a group operation command including a group identifier and group member information of an operation target group by multicast communication has been proposed. A technology to conceal the contents of commands from members who do not belong to the group by securely distributing a common group key only to group members and encrypting the contents of commands issued to the group thereafter with the group key. Has been proposed.

“Detailed Proposal to IEEE 802.21d based on MKB for TGd”, Y. Hanatani et al. , [Online], Jan, 2013, retrieved from the Internet: <URL: https://mentor.ieee.org/802.21/documents>

  However, in the prior art, the contents of the command can be acquired if the device belongs to the destination group. For this reason, there is a problem that if the device belongs to the destination group, a device that is not the target of the group operation can acquire the contents of the command such as a group identifier included in the group operation command.

  The communication control apparatus according to the embodiment includes a reception unit, a determination unit, a group key block generation unit, an encryption unit, and a transmission unit. The receiving unit receives member information designating communication devices belonging to the group and group identification information. The determination unit determines first member information that specifies a communication device that belongs to a group, and second member information that specifies a communication device to be removed from the group. The group key block generation unit generates a first group key and a first group key block. The encryption unit encrypts the group identification information with the first group key to generate first encrypted group identification information, encrypts the group identification information with the second group key, and generates a second encrypted group identification. Generate information. The transmission unit transmits a first command including the first encrypted group identification information and the first group key block, and a second command including the second encrypted group identification information.

1 is a block diagram of a communication system according to an embodiment. The figure which shows the data structure of the group operation command of embodiment. The block diagram of the communication control apparatus of 1st Embodiment. The block diagram of the communication apparatus of 1st Embodiment. The flowchart of the command transmission process of 1st Embodiment. The flowchart of the group operation process of 1st Embodiment. The block diagram of the communication control apparatus of 2nd Embodiment. The block diagram of the communication apparatus of 2nd Embodiment. The hardware block diagram of the apparatus concerning 1st or 2nd embodiment.

  Exemplary embodiments of a communication control apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.

  The communication control device according to each of the following embodiments includes an encryption group identifier, an encryption command identifier, designation information, a group key block (GKB) according to the configuration of one or more communication devices that are targets of group operation. ) To the group member of the group specified by the second group identifier. The encryption group identifier is information obtained by encrypting identification information (first group identifier) for identifying an operation target group with a group key. The encrypted command identifier is information obtained by encrypting the command identifier. The command identifier is identification information for identifying whether the command is for commanding to belong to a group or the command for commanding to leave the group. The designation information is information that designates a communication device to be operated. The group key block is information for deriving a group key shared by communication devices belonging to the group. The group key block is configured such that only the communication device designated by the designation information can obtain the group key.

  In the present embodiment, the information is transmitted to the second group, and is transmitted to the communication device to be operated. Usually, the second group is called a destination group. The destination group may include not only communication devices that are targets of group operations, but also communication devices that are not targets of group operations.

  The communication device to be operated designated by the designation information can obtain the first group identifier and the command identifier by decrypting the encrypted group identifier and the encrypted command identifier using the group key obtained from the group key block. . On the other hand, a communication device not designated by the designation information cannot obtain the group key from the group key block, and therefore cannot know the first group identifier and command identifier.

  In this way, a group member (into a group) is concealed from a communication device that belongs to a destination group but is not an operation target, and an attacker who attempts to eavesdrop on command contents. It is possible to specify the communication device to which it belongs.

(First embodiment)
There is a technique for designating group members (communication devices) belonging to a group by a CS (Complete Subtree) method using a predetermined tree structure (binary tree structure). In this technique, the communication control device issues a command including a group identifier and designation information. The communication device that has received the command participates in the group specified by the group identifier if specified by the specification information, and leaves the group specified by the group identifier if not specified by the specification information. In this technique, only a communication device designated by the designation information issues a command including a group key block from which a group key can be obtained. As a result, the group key can be securely distributed only to the group members.

  In this technique, the group key is kept secret from those other than the group member to be operated. However, all group members of the destination group can obtain the group identifier of the group to be operated, the designation information, and the like, which are information included in the command other than the group key. That is, there is a problem that a communication apparatus that is not a target of group operation can know the contents instructed by the command.

  The above problem can be solved by concealing the group identifier from other than the operation target communication device. A simple method of concealing the group identifier from other than the group members is to encrypt the group identifier with the latest group key distributed by the command. However, when this method is used, a group member who belongs to the group before the operation but is commanded to leave the group after the operation cannot acquire the group identifier of the operation target. Therefore, the command to leave the group does not function correctly.

  Therefore, in the communication system according to the first embodiment, the communication control device selects the latest group key for the communication devices belonging to the group, and encrypts the first group identifier with the selected group key. To generate an encryption group identifier. In addition, the communication control device generates an encrypted command identifier obtained by encrypting a command identifier indicating that the command is a command for belonging to a group, using the selected group key. Then, the communication control device issues a group operation command including an encrypted group identifier, an encrypted command identifier, designation information, and a group key block.

  In addition, the communication control device selects a disposable key for the communication device to be removed from the group, encrypts the first group identifier with the selected disposable key, and generates an encrypted group identifier. Further, the communication control device generates an encrypted command identifier obtained by encrypting a command identifier indicating that the command is a command for leaving the group with the selected group key. Then, the communication control device issues a group operation command including an encrypted group identifier, an encrypted command identifier, designation information, and a group key block.

  As a result, the group operation can be performed while concealing the group to be operated.

  The CS method is known as a method for generating a group key block. In the normal CS method, devices are managed using a management tree in which a node index for identifying a node and a node key are assigned to each node. In accordance with the structure of the management tree, each communication device is assigned a device key that is a set of a node index and a node key. The group management apparatus holds all device keys, and selects a node key according to a procedure defined by the CS method according to the configuration of group members. The group management device encrypts the group key with each selected node key and generates a ciphertext. The group management apparatus distributes encrypted data that is a set of generated ciphertexts and an encrypted data index that specifies a node key to be used for decryption. Thereby, a group key can be securely transmitted only to a desired communication device. The communication device that has received the encrypted data index and the encrypted data checks whether or not the node key specified by the encrypted data index is included in the device key held by itself. If held, the communication device processes the encrypted data using the node key to derive a group key.

  In the present embodiment, the communication control device also serves as the group management device as described above. In this embodiment, the encrypted data index is used as the designation information, and the encrypted data is used as the group key block. Further, by using the group key as a disposable key, a group key block can be created in which only the communication device specified by the encrypted data index can obtain the disposable key.

  As described above, the encrypted data index is information for specifying a node key. The communication apparatus can determine whether or not the own apparatus is an operation target based on whether or not the node key specified by the encrypted data index is included in the device key stored in the own apparatus. Therefore, the encrypted data index can be used as the designation information.

  In the communication system according to the present embodiment, each communication device records in advance leaf identification information (a node index of a leaf node) representing one of the leaves of the tree structure. Each communication device can derive the node index of each node on the path from the root of the tree structure to the leaf specified by the leaf identification information based on the leaf identification information. Each communication device may simply record the node index of each node from the root to the leaf.

  FIG. 1 is a block diagram illustrating an example of a configuration of a communication system according to the present embodiment. As shown in FIG. 1, the communication system of this embodiment has a configuration in which communication devices 200a to 200h and a communication control device 100 are connected via a network 60a or a network 60b.

  Any network form such as the Internet can be applied to the networks 60a and 60b. The network form is not limited to the form shown in FIG. Each device may be connected by one network or may be connected by three or more networks. For example, in FIG. 1, the communication device 200e is connected to the communication control device 100 via both networks 60a and 60b. The communication devices 200a to 200h do not need to be directly connected to the communication control device 100.

  The communication control apparatus 100 is not limited to one, and may be configured to include two or more communication control apparatuses. Since the communication devices 200a to 200h have the same configuration, they may be simply referred to as the communication device 200 below. The number of communication devices 200 is not limited to eight.

  In the present embodiment, the communication control device 100 transmits a group operation command to each communication device 200. FIG. 2 is a diagram illustrating an example of a data structure of the group operation command. As described above, the group operation command includes an encryption group identifier, an encryption command identifier, designation information, and a group key block.

  FIG. 3 is a block diagram illustrating a configuration example of the communication control apparatus 100. As illustrated in FIG. 3, the communication control device 100 includes a device information storage unit 121, a group information storage unit 122, a system information storage unit 123, a reception unit 101, a determination unit 102, a GKB generation unit 103, An encryption unit 104, a message generation unit 105, and a transmission unit 106 are provided.

  The device information storage unit 121 stores information (device management information) used for managing the communication device 200 to be managed. The device information storage unit 121 manages each communication device 200 according to the CS method. That is, each managed communication device 200 is managed (stored) in association with a leaf of a binary tree. It is assumed that each communication device 200 is previously informed of the node key corresponding to each node on the path from the leaf and root to the leaf to which the communication device 200 corresponds. The device management information is, for example, information indicating a binary tree and a correspondence relationship between the communication device 200 and the leaves of the binary tree.

  The group information storage unit 122 stores group information. The group information includes, for example, a group identifier for identifying a group to which one or more communication devices 200 belong, and a device identifier (communication device ID) that is identification information for identifying the communication devices 200 belonging to the group identified by the group identifier. including. For example, the above-described leaf identification information can be used as a device identifier.

  The system information storage unit 123 stores system information including a command identifier that orders to belong to a predetermined group and a command identifier that orders to leave the group. In addition, the system information storage unit 123 may store a schedule for group operations and operation details.

  The receiving unit 101 receives various types of information such as information specifying a group operation target from an external device such as the communication device 200. For example, the receiving unit 101 receives a group identifier of a group to be operated and a list (member information) of device identifiers of the communication devices 200 that belong to the group after the operation. Instead of receiving the list of group identifiers and device identifiers from the receiving unit 101, the communication control device 100 may determine the list.

  The determination unit 102 determines the communication device 200 that is the target of the group operation. For example, the determination unit 102 receives the group identifier and member information of the group to be operated from the reception unit 101. When the determination unit 102 reads information from the group information storage unit 122 and refers to the member information and the read information and determines the communication device 200 to belong to the operation target group, the determination unit 102 determines the first list (first Member information). When the communication device 200 cannot be determined, such as when there is no communication device 200 that belongs to the operation target group, an empty list may be generated as the first list. Further, when the determination unit 102 reads information from the group information storage unit 122 and refers to the member information and the read information, and determines the communication device 200 to be removed from the operation target group, the determination unit 102 determines the second list ( Second member information) is determined. When the communication device 200 cannot be determined, for example, when there is no communication device 200 to be removed from the operation target group, an empty list may be generated as the second list.

  The first list is a list of device identifiers of the communication devices 200 that belong to the operation target group. For example, the determination unit 102 determines the received member information as the first list. The second list is a list of device identifiers of the communication device 200 to be removed from the operation target group. For example, the determination unit 102 determines, as the second list, a list of device identifiers of the communication devices 200 that currently belong to the operation target group but are not included in the received member information. The determination unit 102 sends the first list and the second list to the GKB generation unit 103.

  A processing example for determining the first list and the second list based on the group identifier and the list of device identifiers received from the receiving unit 101 has been given, but without using the information received from the receiving unit 101, the determining unit 102 A group identifier, a first list, and a second list may be determined. For example, the first list and the second list may be determined by selecting a group identifier based on a group operation schedule and operation content stored in advance in the system information storage unit 123. Also, for example, when receiving the network status, the determination unit 102 determines whether or not there is a need for a group change based on the status, and if it is determined that a group change is necessary, determines the group identifier to be operated. Once selected, the first list and the second list may be determined.

  The determination unit 102 sends the group identifier of the operation target group to the encryption unit 104. Further, the determination unit 102 determines first destination information and second destination information from the first list, the second list, and the information stored in the group information storage unit 122, and transmits them to the transmission unit 106. Send to. The destination information is information that identifies a group of communication devices 200. The destination information is selected so as to include at least one communication device 200 that is a target of group operation.

  For example, the first destination information is information including at least the communication device 200 having the device identifier included in the first list. For example, the second destination information is information including at least the communication device 200 having the device identifier included in the second list. When transmitting a command by multicast communication, for example, one or more multicast addresses can be used as destination information.

  The GKB generation unit 103 generates a group key block from which only the designated communication device 200 can obtain a group key. For example, when receiving a list of device identifiers from the determination unit 102, the GKB generation unit 103 selects a group key at random. The GKB generation unit 103 reads necessary information from the device information storage unit 121, and generates a group key block from which only the communication device 200 specified by the device identifier list can obtain a group key.

  In the present embodiment, the GKB generation unit 103 receives the first list and the second list. For this reason, for example, the GKB generating unit 103 uses only the first designation information indicating the communication device 200 designated in the first list and the communication device 200 designated by the first designation information as the first group key. And a first group key block obtained. Further, the GKB generating unit 103 can obtain the second group key only by the second designation information indicating the communication device 200 designated by the second list and the communication device 200 designated by the second designation information. 2 group key blocks are generated. The disposable key described above is used as the second group key.

  The specification information (including the first specification information and the second specification information) may be in any format as long as the information specifies (identifies) the communication device 200 to be operated. As described above, the encrypted data index can be used as the designation information.

  The first group key represents a group key selected for the first list. The second group key represents the group key selected for the second list. The GKB generation unit 103 sends the first group key and the second group key to the encryption unit 104. The GKB generation unit 103 sends the first group key block and the second group key block to the message generation unit 105.

  The encryption unit 104 outputs information (encrypted content) obtained by encrypting the input information (content). For example, when receiving the group identifier to be operated and the first group key, the encryption unit 104 generates a first encrypted group identifier obtained by encrypting the group identifier with the first group key. Further, the encryption unit 104 generates a first encrypted command identifier obtained by encrypting a command identifier that orders membership in a group with a first group key. In addition, when receiving the group identifier to be operated and the second group key, the encryption unit 104 generates a second encrypted group identifier obtained by encrypting the group identifier with the second group key. Also, the encryption unit 104 generates a second encrypted command identifier obtained by encrypting a command identifier that orders to leave the group with the second group key. The encryption unit 104 sends the generated information (a first encryption group identifier, a first encryption command identifier, a second encryption group identifier, and a second encryption command identifier) to the message generation unit 105. .

  The message generation unit 105 generates a group operation command based on the information received from the GKB generation unit 103 and the encryption unit 104. For example, when the message generation unit 105 receives the first encryption group identifier, the first encryption command identifier, the first designation information, and the first group key block, the message generation unit 105 includes the first encryption group identifier, the first encryption command identifier, the first designation information, and the first group key block. A group operation command (first command) is generated. When the message generation unit 105 receives the second encryption group identifier, the second encryption command identifier, the second designation information, and the second group key block, the message generation unit 105 A group operation command (second command) is generated. The message generation unit 105 sends the first group operation command and the second group operation command to the transmission unit 106.

  The transmission unit 106 transmits various data to an external device such as the communication device 200. For example, when receiving the first destination information and the first group operation command, the transmission unit 106 transmits the first group operation command to the communication device 200 specified by the first destination information. Upon receiving the second destination information and the second group operation command, the transmission unit 106 transmits the second group operation command to the communication device 200 specified by the second destination information. The command is transmitted by, for example, multicast communication, but may be transmitted using another communication format such as unicast communication.

  Next, a configuration example of the communication device 200 will be described. FIG. 4 is a block diagram illustrating an example of the configuration of the communication device 200. As illustrated in FIG. 4, the communication device 200 includes a device information storage unit 221, a group information storage unit 222, a system information storage unit 223, a reception unit 201, a GKB processing unit 202, a decoding unit 203, and an operation. Unit 204.

  The device information storage unit 221 stores information unique to the communication device 200 for processing group operation commands. For example, the device information storage unit 221 stores a binary tree used for management of the communication device 200 and information for specifying a leaf corresponding to the own device among the leaves of the binary tree. As information for specifying the leaf in the binary tree, the node index assigned to the corresponding leaf node can be used. The node index (leaf identification information) of the corresponding leaf node can be used as the device identifier (communication device ID) of the communication device 200 as described above. The device information storage unit 221 may store a device key assigned to the communication device 200.

  The group information storage unit 222 stores a group identifier of a group to which the communication device 200 belongs and a group key used for encryption of a command addressed to the group to which the communication apparatus 200 belongs.

  The system information storage unit 223 stores system information including a command identifier that orders to belong to a predetermined group and a command identifier that orders to leave the group.

  The receiving unit 201 receives various information from an external device such as the communication control device 100. For example, the receiving unit 201 receives a group operation command including an encrypted group identifier, an encrypted command identifier, designation information, and a group key block. The receiving unit 201 sends the encrypted group identifier and the encrypted command identifier to the decrypting unit 203, and sends the designation information and the group key block to the GKB processing unit 202.

  The GKB processing unit 202 checks whether the node key designated by the designation information is stored in the device information storage unit 121. If not stored, the GKB processing unit 202 ends the process. If stored, the GKB processing unit 202 processes the group key block using the designated node key to obtain a group key. Then, the GKB processing unit 202 sends the obtained group key to the decryption unit 203.

  The decryption unit 203 decrypts each information encrypted by the encryption unit 104. For example, when receiving the group key, the encrypted group identifier, and the encrypted command identifier, the decryption unit 203 decrypts the encrypted group identifier using the group key to obtain the group identifier, and uses the group key to encrypt the encrypted command identifier. To obtain a command identifier. Then, the decryption unit 203 transmits the group identifier, the command identifier, and the group key to the operation unit 204.

  The operation unit 204 operates a group according to the group identifier and the command identifier. For example, when the command identifier indicates a command for leaving the group, the operation unit 204 deletes the information recorded together with the group identifier in the group information storage unit 222 and removes the own device from the group specified by the group identifier. Let go. In addition, when the command identifier indicates a command for ordering to join the group, the operation unit 204 updates the information stored in the group information storage unit 222 using the received group identifier and the group key, so that the group identifier Make the local device belong to the group specified in. Whether the command identifier indicates a command for commanding to leave the group or a command for commanding to join the group can be determined by referring to the system information stored in the system information storage unit 223, for example.

  The reception unit 101, the determination unit 102, the GKB generation unit 103, the encryption unit 104, the message generation unit 105, the transmission unit 106, the reception unit 201, the GKB processing unit 202, the decryption unit 203, and the operation unit 204 are, for example, , Causing a processing device such as a CPU (Central Processing Unit) to execute a program, that is, it may be realized by software, or may be realized by hardware such as an IC (Integrated Circuit), or software and hardware May be realized in combination.

  Each storage unit (device information storage unit 121, group information storage unit 122, system information storage unit 123, device information storage unit 221, group information storage unit 222, system information storage unit 223) is an HDD (Hard Disk Drive). ), An optical disk, a memory card, a RAM (Random Access Memory), and other commonly used storage media.

  Next, command transmission processing by the communication control apparatus 100 according to the first embodiment configured as described above will be described with reference to FIG. FIG. 5 is a flowchart illustrating an example of command transmission processing according to the present embodiment.

  The receiving unit 101 of the communication control device 100 receives the group identifier of the operation target group and the list of device identifiers of the communication device 200 belonging to the operation target group (step S101). The determination unit 102 determines the communication device 200 that belongs to the operation target group and the communication device 200 that leaves the operation target group (step S102). The determination unit 102, for example, a first list that is a list of device identifiers of the communication devices 200 that belong to the operation target group, and a second list that is a list of device identifiers of the communication devices 200 to be removed from the operation target group. Determine the list.

  The GKB generating unit 103 generates a group key block from which only the communication device 200 designated by the designation information can obtain a group key (step S103). For example, the GKB generation unit 103 generates first designation information indicating the communication device 200 designated by the first list, and only the communication device 200 designated by the first designation information has the first group key. A resulting first group key block is generated. Similarly, the GKB generation unit 103 generates second designation information and a second group key block.

  When the encryption unit 104 receives the group identifier from the reception unit 101 and receives the first group key and the second group key from the GKB generation unit 103, the encryption unit 104 uses the command identifier and the group for ordering to belong to a predetermined group. The command identifier for commanding the detachment is read from the system information storage unit 123. The encryption unit 104 encrypts the first encrypted group identifier obtained by encrypting the group identifier using the first group key and the command identifier used to encrypt the command using the first group key. Generating a second encrypted command identifier obtained by encrypting a second encrypted group identifier obtained by encrypting the group identifier using the identifier and the second group key, and a command identifier ordering separation from the group using the second group key; (Step S104).

  The message generation unit 105 generates a group operation command based on the information received from the GKB generation unit 103 and the encryption unit 104 (step S105). The transmission unit 106 transmits the group operation command generated by the message generation unit 105 to the destination indicated by the destination information determined by the determination unit 102 (step S106).

  Next, group operation processing by the communication apparatus 200 according to the first embodiment configured as described above will be described with reference to FIG. FIG. 6 is a flowchart illustrating an example of group operation processing according to the present embodiment.

  The receiving unit 201 of the communication device 200 receives a group operation command from the communication control device 100 (step S201). Whether the node key specified by the specification information (encrypted data index or the like) in the group operation command is stored in the device information storage unit 221 or the like (is included in the device key of the own device) It is determined whether or not (step S202).

  If the node key is not stored (step S202: No), the group operation process is terminated. When the node key is stored (step S202: Yes), the GKB processing unit 202 acquires the group key by processing the group key block using the node key (step S203).

  Using the obtained group key, the decryption unit 203 decrypts the encrypted group identifier and the encrypted command identifier included in the group operation command, and obtains the group identifier and the command identifier (Step S204).

  Based on the command identifier, the operation unit 204 identifies whether the command is for ordering to belong to the group or the command for ordering to leave the group, and executes the group operation according to the identified command (step S205).

(Modification 1)
The group operation command may include an encrypted multicast address obtained by encrypting a multicast address corresponding to the group identifier with a group key.

(Modification 2)
The command identifier may be sent without encryption. If at least the group identifier is encrypted, it is possible to conceal the group identifier of the group to be operated from the attacker.

(Modification 3)
The device information storage unit 121 and the group information storage unit 122 may be configured as external devices instead of being provided inside the communication control device 100 so that necessary information is read out each time.

(Modification 4)
A command that commands affiliation and a command that commands detachment may be linked and sent as one command. In this case, for example, the communication apparatus 200 may separate a command that commands affiliation from a command and a command that commands detachment, and may execute the above-described processing for each separated command. In this case, transmission of the command identifier may be omitted.

(Modification 5)
The encryption method used for generating and processing the group key block is an encryption with authentication, and the group operation command may not include the designation information. The authenticated encryption is an encryption method that can determine whether or not the decryption process is successful. The GKB processing unit 202 of the communication device 200 tries to process the group key block using all the node keys assigned to itself, and when the processing is successful, transmits the obtained group key to the decryption unit 203. Thereby, the same function as 1st Embodiment is realizable.

  The authenticated encryption can be realized by various technologies such as the MAC-then-Encrypt method, the AES-CCM, and the encryption usage mode such as AES-GCM.

  As described above, according to the first embodiment, the contents of the group operation can be concealed from the communication device that is not the target of the group operation.

(Modification 6)
Although the determination unit 102, the GKB generation unit 103, the encryption unit 104, the message generation unit 105, the device information storage unit 121, and the group information storage unit 122 are given examples provided in one communication control device 100, It may be realized by the communication control device. For example, a first communication control device including a determination unit 102 and a group information storage unit 122, a second communication control device including a GKB generation unit 103, an encryption unit 104, a message generation unit 105, and a device information storage unit 121 And the communication control apparatus 100 may be realized by connecting the first communication control apparatus and the second communication control apparatus via a network.

(Second Embodiment)
The communication system according to the second embodiment includes an encrypted group identifier obtained by encrypting a group identifier by using a group key currently assigned to a group to be operated as a command for ordering to leave the group, and a group. A group operation command including a command identifier for instructing detachment and designation information is used.

  FIG. 7 is a block diagram illustrating an example of a configuration of the communication control apparatus 100-2 according to the second embodiment. As illustrated in FIG. 7, the communication control device 100-2 includes a device information storage unit 121, a group information storage unit 122, a system information storage unit 123, a reception unit 101, a determination unit 102, and a GKB generation unit 103. -2, an encryption unit 104, a message generation unit 105-2, and a transmission unit 106.

  In the second embodiment, the functions of the GKB generation unit 103-2 and the message generation unit 105-2 are different from those in the first embodiment. Since other configurations and functions are the same as those in FIG. 3 which is a block diagram of the communication control apparatus 100 according to the first embodiment, the same reference numerals are given and description thereof is omitted here.

  The GKB generation unit 103-2 does not generate a group key block for the communication device 200-2 to be removed from the group, but generates a group key block only for the communication device 200-2 to belong to the group. .

  The message generation unit 105-2 generates a group operation command that does not include a group key block as a command for leaving the group. Specifically, the group operation command for ordering to leave the group includes an encrypted group identifier obtained by encrypting the group identifier with the group key currently used in the group to be operated, and a command identifier for ordering to leave the group. And designation information (second designation information indicating the communication device 200-2 designated in the second list).

  Thus, in the present embodiment, the group key currently used in the group to be operated is used as the second group key. The group operation command may include an encrypted command identifier obtained by encrypting the command identifier with a group key (second group key) instead of the command identifier.

  FIG. 8 is a block diagram illustrating an example of a configuration of the communication device 200-2 according to the second embodiment. As shown in FIG. 8, the communication device 200-2 includes a device information storage unit 221, a group information storage unit 222, a system information storage unit 223, a reception unit 201, a GKB processing unit 202, and a decoding unit 203-. 2 and an operation unit 204-2.

  In the second embodiment, the functions of the decryption unit 203-2 and the operation unit 204-2 are different from those of the first embodiment. Other configurations and functions are the same as those in FIG. 4 which is a block diagram of the communication apparatus 200 according to the first embodiment, and thus the same reference numerals are given and description thereof is omitted here.

  The decryption unit 203-2 obtains the group identifier by decrypting the encrypted group identifier using the group key stored in the group information storage unit 222 when the command identifier indicates a command for leaving the group. Is different from the decoding unit 203 of the first embodiment.

  The operation unit 204-2 determines whether or not the group key currently used in the obtained group identifier matches the group key used for decryption. If they match, the operation unit 204-2 is identified by the obtained group identifier. To leave the group.

  Note that the processing when ordering to belong to a group is the same as in the first embodiment. In the present embodiment, unlike the first embodiment, it is not necessary to deliver the group key used for encryption when ordering to leave the group. For this reason, it is not necessary to include the group key block in the command, and the communication cost is excellent. On the other hand, since the communication device 200-2 belonging to the group to be operated can acquire the content of the command, only weak security is satisfied as compared with the first embodiment. However, even when leaving the group is ordered, the contents of the group operation can be concealed at least from communication devices that do not belong to the group to be operated.

(Modification)
You may use authentication encryption for encryption of a group identifier. The communication device 200-2 (decryption unit 203-2) that has received the group operation command attempts to decrypt the encrypted group identifier using each group key. When the decoding is successful, the operation unit 204-2 leaves the group specified by the group identifier obtained as a result of the decoding.

  As described above, according to the first and second embodiments, the confidentiality of the contents of the group operation can be improved.

  Next, a hardware configuration of a device (communication control device, communication device) according to the first or second embodiment will be described with reference to FIG. FIG. 9 is an explanatory diagram showing the hardware configuration of the device according to the first or second embodiment.

  A device according to the first or second embodiment is connected to a control device such as a CPU (Central Processing Unit) 51, a storage device such as a ROM (Read Only Memory) 52 and a RAM (Random Access Memory) 53, and a network. A communication I / F 54 that performs communication and a bus 61 that connects each unit are provided.

  A program executed by the apparatus according to the first or second embodiment is provided by being incorporated in advance in the ROM 52 or the like.

  The program executed by the apparatus according to the first or second embodiment is an installable or executable file, which is a CD-ROM (Compact Disk Read Only Memory), a flexible disk (FD), a CD-R. (Compact Disk Recordable), DVD (Digital Versatile Disk) or the like may be recorded on a computer-readable recording medium and provided as a computer program product.

  Furthermore, the program executed by the apparatus according to the first or second embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. . The program executed by the apparatus according to the first or second embodiment may be provided or distributed via a network such as the Internet.

  The program executed by the device according to the first or second embodiment can cause a computer to function as each unit of the above-described device. In this computer, the CPU 51 can read a program from a computer-readable storage medium onto a main storage device and execute the program.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Claims (12)

A communication control device connected to a plurality of communication devices via a network,
First member information for designating communication devices to belong to the group based on member information for designating communication devices belonging to a group among the plurality of communication devices and group identification information for identifying the group; and the group A determination unit for determining second member information for designating a communication device to be removed from;
Based on the first member information, a first group key and a first group key block from which the communication device specified by the first member information can obtain the first group key are generated. A group key block generator,
The group identification information is encrypted with the first group key to generate first encrypted group identification information, and the group is obtained with a second group key from which a communication device specified by the second member information is obtained. an encryption unit for generating a second encrypted group identification information to encrypt the identification information,
A first command including the first encryption group identification information and the first group key block, and a second command including the second encryption group identification information, at least one of the plurality of A transmission unit for transmitting to the communication device;
A communication control device comprising: The group key block generation unit further includes a second group key based on the second member information, and a communication device specified by the second member information can obtain the second group key. Two group key blocks,
The transmitting unit transmits the second command including the second encrypted group identification information and the second group key block;
The communication control apparatus according to claim 1. The transmission unit transmits the first command to a destination group of a communication device including at least one communication device not specified by the first member information, and is not specified by the second member information Transmitting the second command to a destination group of a communication device including at least one of
The communication control apparatus according to claim 1 or 2 . The transmission unit transmits one command including the first command and the second command;
The communication control apparatus according to claim 1 or 2 . The transmitting unit transmits the one command to a destination group of a communication device including at least one communication device not specified by the first member information and the second member information;
The communication control apparatus according to claim 4. A storage unit for storing a management tree for managing device identification information for identifying the plurality of communication devices in a binary tree structure;
The group key block generation unit is information expressed by a CS (Complete Subtree) method based on the specified device identification information among the device identification information managed by the management tree, and the communication belonging to the group Generating designation information for designating the device identification information of a device and the first group key block;
The communication control apparatus according to claim 1 or 2 . The encryption unit further encrypts command identification information for identifying whether or not the command is the first command to generate first encrypted command identification information,
The transmitting unit transmits the first command including the first encrypted group identification information, the first group key block, and the first encrypted command identification information;
The communication control apparatus according to claim 1 or 2 . The group key block generation unit generates the first group key block based on an authenticated encryption method;
The communication control apparatus according to claim 1 or 2 . A computer connected to multiple communication devices via a network
First member information for designating communication devices to belong to the group based on member information for designating communication devices belonging to a group among the plurality of communication devices and group identification information for identifying the group; and the group A determination unit for determining second member information for designating a communication device to be removed from;
Based on the first member information, a first group key and a first group key block from which the communication device specified by the first member information can obtain the first group key are generated. A group key block generator,
The group identification information is encrypted with the first group key to generate first encrypted group identification information, and the group is obtained with a second group key from which a communication device specified by the second member information is obtained. an encryption unit for generating a second encrypted group identification information to encrypt the identification information,
A first command including the first encryption group identification information and the first group key block, and a second command including the second encryption group identification information, at least one of the plurality of A transmitter for transmitting to the communication device;
Program to function as. A receiver for receiving a command including encrypted group identification information;
A decryption unit for generating group identification information by decrypting the encrypted group identification information with a group key;
Using the group identification information and the group key, an operation unit that causes the device to belong to or leave the group identified by the group identification information ,
The receiving unit includes a first command including first encrypted group identification information and a first group key block, and a second command including second encrypted group identification information and a second group key block. The command,
A group key block processing unit that obtains a first group key based on the first group key block and obtains a second group key based on the second group key block;
The decryption unit generates first group identification information by decrypting the first encrypted group identification information with the first group key, and generates the second encrypted group with the second group key. Generating second group identification information by decoding the identification information;
The operation unit causes the own apparatus to belong to a group identified by the first group identification information using the first group identification information and the first group key, and the second group identification information Using the second group key to detach itself from the group identified by the second group identification information,
Communication equipment. The receiving unit receives a command further including a first encrypted command identifier and a command further including a second encrypted command identifier;
The decryption unit generates a first command identifier by decrypting the first encrypted command identifier with the first group key, and generates the second encrypted command identifier with the second group key. Generating a second command identifier by decoding;
The operation unit uses the first group identification information, the first group key, and the first command identifier to cause the own device to belong to a group identified by the first group identification information, Using the second group identification information and the second group key , to detach itself from the group identified by the second group identification information;
The communication device according to claim 10 . The encrypted group identification information is encrypted by an authenticated encryption method,
The decryption unit performs decryption of the encryption group identification information based on the authenticated encryption method,
The operation unit uses the group identification information and the group key when decryption is successful, and causes the device to belong to or leave the group identified by the group identification information.
The communication device according to claim 10 .

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