JPH0766803A - Multiple address ciphering communication method and its system - Google Patents

Abstract

PURPOSE:To execute multiple address ciphering communication safely even when members change dynamically. CONSTITUTION:A process A obtains a conversation key (a) ciphered by a secret key A from an authentication server 3 and verification information ciphered by a secret key alpha of a group management server 5. The authentication information includes the conversation key (a). Then the process A decodes the information by using its own ciphering key A, obtains a key a and applies subscription to a group G1 to a group management server 5 by using the conversation key (a). The authentication information is added to the application. The group management server 5 decodes the authentication information by using its own ciphering key alpha to check the authentication and to obtain the conversation key (a) and then distributes a common ciphered key g1 ciphered by the conversation key (a) to the process A. The process A decodes the common ciphering key g1 by using the conversation key (a) and executes multiple address ciphering communication by using the common ciphering key g1. As a result, the multiple address ciphering communication between processes whose group members change dynamically is executed properly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadcast cipher communication method and system, and more specifically, to a broadcast cipher communication between a plurality of processes operating on a plurality of computers connected to a network. The present invention relates to a communication method and system.

[0002]

2. Description of the Related Art In a distributed processing environment, processes operating on a computer progress processing by exchanging messages with each other. Therefore, in order to improve the processing speed, it is necessary to improve the efficiency of interprocess communication. As an effective method for improving the efficiency of this inter-process communication, "Process Grou
ps and Group Communications: Luping Liang, Samuel
T. Chanson and Gerald W. Neufeld ； University of Brit
ish Columbia: Computer, February 1990; pp.56-65, IE
"EE" discloses a technique for performing broadcast communication between a plurality of processes. When this broadcast communication is used, there are advantages that the overhead of the transmission source process and the network can be reduced, and that the transmission destination process does not have to be described separately and that the user program can be simplified.

On the other hand, as a cryptographic communication method in a network, "Kerberos: An Authentication Service for
Open Network Systems: J. G. Steiner et al .; USENIX Wint
er Conference, February 1988; pp.191-202 ", Kerberos authentication service is disclosed. In this Kerberos authentication service, client computer (service user) and server computer (service provider)
Connect the authentication server to the network to which is connected.
This authentication server holds a private key for each computer.
When the client computer uses the service of the server computer, it first requests the authentication server for authentication. The authentication server checks the legitimacy of the requesting client computer, and if valid, sends the authentication information encrypted with the server computer's encryption key and the conversation key encrypted with the requesting client computer's encryption key to the client computer. To do. The authentication information also includes a conversation key. The client computer decrypts the conversation key with its own secret key, encrypts the communication data with the conversation key, and adds the authentication information to it,
Send to server computer. The server computer decrypts the authentication information with its own private key, checks the validity of the client computer, and obtains the conversation key. Then, the conversation key is used to provide a service to the client computer.

[0004]

When performing broadcast communication between a plurality of processes via a network, there is a problem that communication information is visible on the network. For this reason,
Although it may be possible to perform broadcast cryptographic communication, the conventional cryptographic communication method such as the above Kerberos authentication service does not take into consideration the situation in which the group members dynamically change. There is a problem that it is not possible to use broadcast encryption communication between them. Therefore, an object of the present invention is to provide a broadcast cipher communication method and system capable of safely carrying out the broadcast cipher communication even when a group member dynamically changes.

[0005]

SUMMARY OF THE INVENTION In a first aspect, the present invention is a broadcast encryption communication method for performing broadcast encryption communication between a plurality of processes operating on a plurality of computers connected to a network. , Connecting an authentication server and a group management server to the network, the process holds its own encryption key, the authentication server holds the encryption key of each process and the group management server's encryption key and conversation key, and the group management The server holds its own encryption key and the shared encryption key of the group, and the process attempting to join the group sends a credential request message to the authentication server, and the authentication server that receives the message sends the authentication information request message to the authentication server. Authentication information delivery message containing conversation key encrypted with process encryption key and conversation key encrypted with group management server encryption key The process that transmitted and received this decrypts the conversation key with its own encryption key, encrypts at least one of the information indicating the own process and the information indicating the group to which the user wants to join with the conversation key, and the encryption key of the group management server. The subscription request message added with the conversation key encrypted by is sent to the group management server, and the group management server receiving this message decrypts the conversation key with its own encryption key and uses the conversation key to indicate the information indicating the process and A shared cryptographic key distribution message including the shared cryptographic key of the group, which is obtained by obtaining the information indicating the group to which the user wants to join and encrypted by the conversational key, is transmitted, and the process receiving the message uses the conversational key to transmit the shared cryptographic key. (EN) A broadcast encryption communication method characterized by performing broadcast encryption communication within a group by acquiring and using the shared encryption key.

According to a second aspect of the present invention, in the broadcast encryption communication method, the group management server generates a new shared encryption key at a predetermined timing and encrypts the new shared encryption key with a conventional shared encryption key. A shared encryption key change broadcast notification message including a new shared encryption key is created and broadcast to the processes belonging to the group, and the process uses the shared encryption key from the received shared encryption key change broadcast notification message. A new shared encryption key is obtained by using the new shared encryption key, and then the new shared encryption key is used to perform the broadcast encryption communication.

According to a third aspect of the present invention, in the above-described broadcast encryption communication method, the group management server generates a new shared encryption key for each predetermined period, and a continuous joining inquiry is given to a process belonging to the group. A shared encryption key change individual notification message including the new shared encryption key encrypted by the conversation key with the process is created for the process that broadcasts the message and returns the continuous join response message to the process. Then, the process that does not return the continuous join response message is deleted from the group, and the process obtains a new shared encryption key using the conversation key from the received shared encryption key change individual notification message, and thereafter. Provides a broadcast encryption communication method characterized by performing broadcast encryption communication using a new shared encryption key.

[0008] In a fourth aspect, the present invention connects a plurality of computers, an authentication server, and a group management server to a network, and a process operating on the computer holds its own encryption key and performs authentication. An authentication information request message sending means for sending an authentication information request message to a server, a conversation key acquisition means for obtaining a conversation key from the received authentication information delivery message using its own encryption key, and the conversation key indicates the own process. Subscription request message sending means for creating a subscription request message to which at least one of information or information indicating a group to be subscribed is encrypted and a conversation key encrypted with the encryption key of the group management server is added and transmitted to the group management server; Obtaining a shared encryption key using the conversation key from the received shared encryption key distribution message Obtaining a shared encryption key And a broadcast cipher communication message transmitting means for creating and transmitting a broadcast cipher communication message using the shared cipher key, and acquiring the broadcast data from the received broadcast cipher communication message using the shared cipher key. The authentication server holds a cryptographic key of each process, a cryptographic key of the group management server, and a conversation key, and when the process requesting the authentication information is authenticated, the authentication server is provided with The group management server is provided with an authentication information delivery message transmitting means for creating and transmitting an authentication information delivery message including a conversation key encrypted with a key and a conversation key encrypted with the encryption key of the group management server, and the group management server is self-encrypted. A group that holds the key and the shared encryption key of each group, and decrypts the received subscription request message with its own encryption key to obtain the conversation key. And the key acquisition means,
A subscription information acquisition unit that uses the conversation key to obtain information indicating an application source process and information indicating a group to which the user wants to join, and the group encrypted with the conversation key when permitting the process to join the group. And a shared encryption key distribution message transmitting means for creating and transmitting a shared encryption key distribution message including the shared encryption key of 1.

According to a fifth aspect of the present invention, in the broadcast encryption communication system, the group management server generates a new shared encryption key at a predetermined timing and encrypts the new shared encryption key with the previous shared encryption key. A shared encryption key update control means for creating and transmitting a shared encryption key change broadcast notification message including a new shared encryption key is provided, and the process described above receives the shared encryption key from the received shared encryption key change broadcast notification message. (EN) A broadcast encryption communication system characterized by comprising a shared encryption key updating means for acquiring a new shared encryption key by using it and using the new shared encryption key as a subsequent shared encryption key.

According to a sixth aspect of the present invention, in the broadcast encryption communication system, the group management server generates a new shared encryption key for each predetermined period and asks the process belonging to the group to continuously join the inquiry. A shared encryption key change individual notification message including the new shared encryption key encrypted by the conversation key with the process is created for the process that broadcasts the message and returns the continuous join response message to the process. The process not transmitting the continuous join response message is provided with group member confirmation control means for deleting from the group, and the process uses the conversation key from the received shared encryption key change individual notification message to generate a new shared encryption key. A shared encryption key updating means for obtaining a key and using the new shared encryption key as a subsequent shared encryption key is provided. To provide a cryptographic communication system.

[0011]

In the broadcast encryption communication method of the present invention according to the first aspect and the broadcast encryption communication system of the present invention according to the fourth aspect, the process is first encrypted from the authentication server with the secret key of the process. The authentication information encrypted with the generated conversation key and the private key of the group management server is obtained. This authentication information includes the conversation key. Next, the process decrypts with its own encryption key to obtain the conversation key, and uses the conversation key to apply to the group management server for joining the group. The authentication information is added to this application.
The group management server decrypts the authentication information with its own encryption key, inspects the authentication information, and obtains the conversation key. And
Distribute the shared encryption key encrypted with the conversation key to the process.
The process decrypts the shared encryption key with the conversation key and uses it to perform broadcast encryption communication. According to this, to be certified by an authentication server that is a reliable third-party certification authority,
The shared encryption key is distributed through a secure communication channel encrypted by the conversation key, and the process does not need to know other group members, so that the group members can be broadcast safely even when the group members dynamically change. It becomes possible to carry out encrypted communication.

In the broadcast encryption communication method of the present invention according to the second aspect and the broadcast encryption communication system of the present invention according to the fifth aspect, since the shared encryption key is updated at a predetermined timing, security against cryptographic attacks is ensured. You can improve the property. In the broadcast encryption communication method of the present invention according to the third aspect and the broadcast encryption communication system of the present invention according to the sixth aspect,
Since the group members are sorted and the shared encryption key is updated every predetermined period, security against encryption leakage can be improved.

[0013]

EXAMPLES The present invention will be described in more detail with reference to the examples shown in the drawings. The present invention is not limited to this.

FIG. 1 is a block diagram of a broadcast encryption communication system according to an embodiment of the present invention. This broadcast encryption communication system (100) connects a plurality of computers (2-1), (2-2), (2-3), (2-4) to a network (1), and also an authentication server. The KDC (3) and the group management server MGR (5) are basically connected to each other.

A plurality of computers (2-1), (2-2),
On (2-3) and (2-4), the process A
(6-1), B (6-1), C (6-1), D (6-
1) is working. Each process A (6-1), B (6
-1), C (6-1), and D (6-1) have unique secret keys A, B, C, and D, respectively.

The authentication server KDC (3) delivers the authentication information to the requesting process in response to the authentication request from the process. In addition, each of the processes A (6-1), B
(6-1), C (6-1), D (6-1) private key A,
Owns B, C, D, and manages group MG
The private key α of R (5) and the conversation key between the process and the group management server are stored.

The group management server MGR (5) manages the constituent members of the group. In addition to possessing a unique encryption key α, the shared encryption key g1, for each group
... is stored.

FIG. 2 shows the group management server MGR (5).
3 is a detailed configuration diagram of FIG. The group composition management unit (20)
The process group management table (24) manages the members of the group. The process group management table (24) includes a group management list and a process management list. The group management list is
The group identifier corresponding to each group, the broadcast address, the shared encryption key, and the old shared encryption key are managed in a list format. The process management list manages a process identifier, address information, authentication information, and conversation key corresponding to each process belonging to each group in a list format. As will be described later, the shared encryption key is generated by the group configuration management unit (20). Also, the conversation key is extracted from the authentication information received from the process.

The message transmitting / receiving unit (23) transmits / receives a message to / from a process via the network 1. At that time, the message is encrypted or decrypted.

When the process is requested to join the group, the group joining permission control unit (21) judges whether or not the joining is permitted based on the group joining permission control information, and permits or rejects the joining to the group.

The group shared encryption key update control unit 22 changes the shared encryption key at a predetermined timing and sends a broadcast notification to the group members.

The group member confirmation control unit 28 confirms the intention to belong to the group to the group members every predetermined period, simultaneously changes the shared encryption key, and confirms the intention to belong to the group. Broadcast notification only to.

FIG. 3 is a sequence diagram showing a procedure when the process A (6-1) tries to join the group. First, the process A (6-1) is the authentication server KD.
An authentication information request message (4 in FIG. 4) is sent to C (3).
Send 0). When the authentication information delivery message (41 in FIG. 5) is received from the authentication server KDC (3), the authentication information (49 in FIG. 6) is taken out and a subscription request message (42 in FIG. 7) with it is created, Management server MG
Send to R (5). When the subscription is permitted, the shared encryption key distribution message (43 in FIG. 8) is received from the group management server MGR (5). By taking out the shared encryption key from the shared encryption key distribution message, the broadcast encryption communication can be performed thereafter to the members of the group.

FIG. 4 shows an authentication information request message (40).
It is a data configuration diagram of. In this authentication information request message (40), the address "KDC address" of the authentication server (3) is stored in the destination address field (40-1), and the "authentication information request" is stored in the message type field (40-2). Then, the "process identifier A" indicating the process A of the request source is stored in the request source field (40-3), and the group management server (5) as the other party who presents the authentication information in the presentation destination field (40-4). "MRG
"Identifier" is stored.

FIG. 5 shows an authentication information delivery message (41).
It is a data configuration diagram of. This authentication information delivery message (41) stores “process identifier A” indicating the requesting process A in the destination address field (41-1) and “authentication information delivery” in the message type field (41-2). And stores "authentication information" about the requesting process A in the authentication information field (41-3),
Requesting process A in the conversation key field (41-4)
The "conversation key a" between (6-1) and the group management server (5) of the presentation destination is stored. Note that the authentication information is encrypted with the secret key α of the group management server (5), and then
Further, it is encrypted with the secret key A of the process A, which is represented by {{authentication information} α} A. The conversation key a is encrypted with the secret key A of the process A, and this is represented by {conversation key a} A. In this embodiment, it is assumed that each field is encrypted, but a plurality of fields may be collectively encrypted. For example, {{authentication information} α + conversation key a} A may be used.

FIG. 6 is a data structure diagram of the authentication information (49). This authentication information (49) stores “process identifier A” in the request source field (49-1), stores “MRG identifier” in the presentation destination field (49-2),
"Address information of process identifier A" is stored in the request source address information field (49-3), authentication time is stored in the time field (49-4), and "conversation key a" is stored in the conversation key field (49-5). Is stored.

FIG. 7 is a data structure diagram of the subscription request message (42). This subscription request message (42)
Stores the address “MRG address” of the group management server (5) in the destination address field (42-1), stores “subscription request” in the message type field (42-2), and stores the authentication information field (42- "Authentication information" is stored in 3), and the application source address information field (4
The “process identifier A” indicating the process A of the application source is stored in 2-4), and the group identifier field (42-5)
“Group identifier G1”, which is the identifier of the group G1 that applies for joining, is stored. The authentication information is encrypted with the secret key α of the group management server (5), which is represented by {authentication information} α. The process identifier A is encrypted with the conversation key a, which is represented by {process identifier A} a. The group identifier G1 is the conversation key a.
Are encrypted by the following, and this is represented by {group identifier G1} a.

FIG. 8 shows a shared encryption key distribution message (4
It is a data block diagram of 3). This shared encryption key distribution message (43) is stored in the destination address field (43-1).
Applicant's process address "Process A address"
, "Shared encryption key distribution" is stored in the message type field (43-2), and "Group identifier G1" which is the identifier of the group G1 permitted to join is stored in the group identifier field (43-3). The shared encryption key field (43-4) stores the “shared encryption key g1” which is the shared encryption key of the group G1. The group identifier G1 is encrypted with the conversation key a and is represented by {group identifier G1} a. The shared cryptographic key g1 is encrypted with the conversation key a, which is represented by {shared cryptographic key g1} a.

FIG. 9 is a flow chart of a group joining procedure process executed by the process A (6-1). Step 20
In 1, the authentication information request message (40) of FIG. 4 is created and transmitted to the authentication server (3). The authentication server (3) receiving this authentication information request message (40) is shown in FIG.
The authentication information delivery message (41) is created and sent to the process A. In step 202, the process waits until the authentication information delivery message (41) is received from the authentication server (3). If received, the process proceeds to step 203. In step 203, the authentication information delivery message (41) is decrypted using the secret key A to obtain {authentication information} α and conversation key a encrypted with the secret key α.

In step 204, the subscription request message (42) of FIG. 7 is created and transmitted to the group management server (5). The group management server (5), which has received the join request message (42), creates a join disapproval message or the shared encryption key distribution message (43) in FIG. 8 and sends it to the process A. In step 205, it is determined whether or not a subscription disapproval message is received from the group management server (5). If not received, the process proceeds to step 206. If received, error processing is performed. Step 206
Then, it is determined whether the shared encryption key distribution message is received from the group management server (5). If not received, the process returns to step 205. If received, step 207
Proceed to. In step 207, the conversation key a is used for decryption to obtain the shared encryption key g1.

FIG. 10 is a flow chart showing an authentication information delivery process executed by the authentication server (3). Step 301
Now, check the validity of the process that requested the authentication information,
If it is valid, the authentication information delivery message (4
Create 1) and send it to the process.

FIG. 11 is a flow chart of a group joining permission control process executed by the group joining permission control unit (21) of the group management server (5). In step 211,
When the subscription request message (42) is received, the authentication information field (42-3) is decrypted with the secret key α, and the authentication information (49) is acquired. From this, it can be seen that the process of the application source is process A. Also, the conversation key a is obtained. In step 212, the subscription request message (4
The application source address information field (42-4) and the group identifier field (42-5) of 2) are decrypted with the conversation key a. From this, it can be seen that the group G1 has been applied for.

In step 213, it is examined whether to disallow or allow the process A to join the group G1. In step 214, in the case of disapproval, step 21
5, the process proceeds to step 216 in the case of permission.

In step 215, a subscription disapproval message (not shown) is created and sent to the process A.

In step 216, the group configuration management unit 20 is notified and the process A is registered as a member of the group G1. In step 217, the group configuration management unit 20 is notified and the shared encryption key g1 of the group G1 is reported. In step 218, the shared encryption key distribution message (43) in FIG. 8 is created and sent to the process A.

This is the end of the description of the operation when the process A joins the group G1. Other processes can similarly join the group and acquire the shared encryption key of the group.

FIG. 12 is a sequence diagram when the process A (6-1) performs the broadcast encryption communication with the members of the group G1. The process A (6-1) uses the acquired shared encryption key g1 to broadcast the encrypted communication message (see FIG. 13).
44) is created and broadcast to the group members via the network 1. This broadcast encrypted communication message can be decrypted only by the group member having the shared encryption key g1.

FIG. 13 shows a broadcast encrypted communication message (4
It is a data block diagram of 4). This broadcast encrypted communication message (44) stores "address of group G1" which is the address of the broadcast group in the destination address field (44-1), and the message type field (44-2).
"Broadcast data" is stored in the group identifier field, "group identifier G1" that is the identifier of the broadcast group is stored in the group identifier field (44-3), and the transmission source field (44-4) is stored.
The "process identifier A" indicating the process of the transmission source is stored in and the "broadcast data" is stored in the data field (44-5). The group identifier G1 is encrypted with the shared encryption key g1 and is represented by {group identifier G1} g1. The process identifier A is encrypted with the shared encryption key g1 and is represented by {process identifier A} g1. Further, the broadcast data is encrypted with the shared encryption key g1, which is represented by {broadcast data} g1.

FIG. 14 is a flow chart of the operation when the process carries out broadcast encryption communication. FIG. 14A shows the processing at the time of transmission. In step 251, the broadcast encrypted communication message (44) of FIG. 13 is created and broadcasted to all the processes of the group G1. FIG. 14B shows a process upon reception, and in step 261, the received broadcast cipher communication message (44) is decrypted by the shared cipher key to obtain the broadcast data.

FIG. 15 is a sequence diagram when the group management server (5) broadcasts the change of the shared encryption key to the group members at a predetermined timing. The group management server (5) generates a new shared encryption key, for example, every minute, and a shared encryption key change broadcast notification message (4 in FIG. 16).
5) is created and broadcast to each process of group members. After that, the group member performs the broadcast encryption communication by using the new shared encryption key.

FIG. 16 is a data structure diagram of the shared encryption key change broadcast notification message (45). In this shared encryption key change broadcast notification message (45), the address of the broadcast group "address of group G1" is stored in the destination address field (45-1), and the "message type field (45-2)" is stored. “Shared encryption key change” is stored, the group identifier field (45-3) is stored with “Group identifier G1” which is the identifier of the broadcast group, and the new shared encryption key is stored in the new shared encryption key field (45-4). The “shared encryption key g1 ′” is stored. The group identifier G1 is encrypted with the old shared encryption key g1 and is represented by {group identifier G1} g1. Further, the new shared encryption key g1 ′ is encrypted with the old shared encryption key g1 and is represented by {shared encryption key g1 ′} g1.

FIG. 17 is a flow chart of the group shared encryption key update control processing executed by the group shared encryption key update control unit (22) of the group management server (5). In step 221, when the condition for updating the shared encryption key is satisfied,
A new shared encryption key g1 'for the group G1 is generated. In step 222, the process group management table 24
The shared encryption key g1 of the group management list in which the information of the group G1 in FIG. 2 is registered is moved to the entry of the old shared encryption key, and the new shared encryption key g1 ′ is registered in the entry of the shared encryption key. In step 223, the shared encryption key change broadcast notification message (45) shown in FIG. 16 is created and broadcast to the processes belonging to the group G1. Process A (6-1), Process B (6-2), Process C that received this shared encryption key change broadcast notification message (45)
In (6-3), decryption is performed using the shared encryption key g1 to obtain a new shared encryption key g1 ′, and thereafter, broadcast encryption communication within the group G1 is performed using the shared encryption key g1 ′.

By executing the group shared key update control process, the shared encryption key is updated by dividing the period, so that the security against cryptographic attack can be enhanced.

In FIG. 18, the group management server (5) inquires the group member about the intention to continue joining at predetermined intervals, reconfigures the group only with the processes that respond, and changes the shared encryption key in each process. It is a sequence diagram when notifying individually. The group management server (5) creates a continuation confirmation question message (46 in FIG. 19), for example, every 6 minutes, and broadcasts it to each process of the group members.
Also, a new shared encryption key is generated. Then, the shared encryption key change individual notification message (48 in FIG. 21) is sent only to the process that has returned the continuous subscription response message (47 in FIG. 20) by the predetermined time limit, and the shared encryption key is changed. After that, the group member performs the broadcast encryption communication by using the new shared encryption key.

FIG. 19 shows a continuous subscription inquiry message (4
It is a data block diagram of 6). This continuous join inquiry message (46) stores the address of the broadcast group, "address of group G1," in the destination address field (46-1), and the message type field (46-2).
"Continuous subscription question" is stored in the group, and "Group identifier G1" which is the identifier of the broadcast group is stored in the group identifier field (46-3). The group identifier G1 is encrypted with the shared encryption key g1 ′, which is represented by {group identifier G1} g1 ′.

FIG. 20 shows a continuous join response message (4
It is a data block diagram of 7). This continuous join response message (47) stores the address "MRG address" of the group management server (5) in the destination address field (47-1), and the message type field (47-2).
"Continuous subscription confirmation" is stored in the group identifier, "Group identifier G1" that is the identifier of the group G1 is stored in the group identifier field (47-3), and the address of the process of the response source is stored in the response source address field (47-4). “Address of process A” is stored. The group identifier G1 and the address of the process A are both encrypted with the conversation key a, which is represented by {group identifier G1} a {process A address} a.

FIG. 21 is a data structure diagram of the shared encryption key change individual notification message (48). This shared encryption key change individual notification message (48) stores the address “process A address” of the response source process in the destination address field (48-1) and “shared encryption key” in the message type field (48-2). “Change” is stored, the group identifier field (48-3) stores “group identifier G1” which is the identifier of the group G1, and the shared encryption key field (48-4) stores a new shared encryption key of the group G1. The "shared encryption key g1""is stored. In addition,
The group identifier G1 is encrypted with the conversation key a,
This is represented by {group identifier G1} a. Further, the shared encryption key g1 ″ is encrypted with the conversation key a, which is represented by {shared encryption key g1 ″} a.

FIG. 22 is a flow chart of the group member confirmation control processing executed by the group member confirmation control unit (28) of the group management server (5). In step 231, a new shared encryption key g1 ″ of the group G1 is generated. The interval at which the group member confirmation control process is executed is preferably longer than the interval at which the shared encryption key update control process is executed. Then
Create a continuous subscription question message (46)
Broadcast notifications to processes belonging to 1. Step 234
Now start the timer.

In step 236, it is checked whether the continuous join response message (47) has been received. If it has been received, the process proceeds to step 237, and if it has not been received, the process proceeds to step 240. In step 237, the conversation key with the response source process is obtained from the response source address of the continuous join response message (47), the group identifier of the continuous join response message (47) is decrypted, and the validity of the response is checked. If it is valid, the process proceeds to step 239, and if it is not valid, the process is terminated. In step 239, the shared encryption key change individual notification message (48) is created. In step 240, it is checked whether the timer has timed out. If not, the process returns to step 236. If the time is out, the process proceeds to step 241.

In step 241, the information of the process which has not responded is deleted from the process management list of the process group management table (FIG. 2). In step 242, the shared encryption key change individual notification message (the number of which is the number of responding processes) created and saved in step 239 is continuously transmitted.

By executing the group member confirmation control processing, the group members are organized by dividing the period and the shared encryption key is also changed, so that the security against encryption leakage can be enhanced.

In the above embodiment, the authentication server (3) and the group management server (5) are separately mounted, but the functions of the group management server (5) are integrated into the authentication server (3). May be realized. Further, a plurality of group management servers (5) may be arranged.

[0053]

According to the broadcast encryption communication method and system of the present invention, the shared encryption key can be safely distributed even if the group members dynamically change. Also, the security against cryptographic attacks can be improved. Further, it becomes possible to improve the security against the leakage of the code. Further, according to the group management server of the present invention, it is possible to preferably realize the broadcast encryption communication method and system.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a broadcast encryption communication system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a group management server according to an embodiment of the present invention.

FIG. 3 is a sequence diagram showing a procedure when process A attempts to join a group.

FIG. 4 is a data structure diagram of an authentication information request message.

FIG. 5 is a data structure diagram of an authentication information delivery message.

FIG. 6 is a data structure diagram of authentication information.

FIG. 7 is a data structure diagram of a subscription request message.

FIG. 8 is a data structure diagram of a shared key distribution message.

9 is a flowchart of a group joining procedure process executed by process A. FIG.

FIG. 10 is a flowchart showing an authentication information delivery process executed by the authentication server.

FIG. 11 is a flowchart showing a group joining permission control process executed by the group management server.

FIG. 12 is a sequence diagram when the process A performs broadcast encryption communication with the members of the group G1.

FIG. 13 is a data structure diagram of a broadcast encrypted communication message.

FIG. 14 is a flow diagram of operations when a process performs broadcast cryptographic communication.

FIG. 15 is a sequence diagram when the group management server broadcasts the change of the shared encryption key to the group members.

FIG. 16 is a data structure diagram of a shared encryption key change broadcast notification message.

FIG. 17 is a flowchart of a group shared encryption key update control process executed by a group shared encryption key update control unit of the group management server.

FIG. 18 is a sequence diagram when the group management server inquires a group member about intention to continue joining and individually notifies the process that has responded of the change of the shared encryption key.

FIG. 19 is a data structure diagram of a continuous subscription inquiry message.

FIG. 20 is a data structure diagram of a continuous join response message.

FIG. 21 is a data structure diagram of a shared encryption key change individual notification message.

FIG. 22 is a flowchart of a group member confirmation control process executed by a group member confirmation control unit of the group management server.

[Explanation of symbols]

 100 Broadcast encryption communication system 1 Network 2-1, 2-2, 2-3, 2-4 Computer 3 Authentication server 5 Group management server 6-1 Process A 6-2 Process B 6-3 Process C 6-4 process D 20 Process group configuration management unit 21 Group join permission control unit 22 Group shared encryption key update control unit 23 Message transmission / reception unit 24 Process group management table 28 Group member confirmation control unit

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Claims (6)

[Claims] 1. A broadcast encryption communication method for performing broadcast encryption communication between a plurality of processes operating on a plurality of computers connected to a network, wherein an authentication server and a group management server are connected to the network, The process holds its own encryption key, the authentication server holds the encryption key of each process, the encryption key of the group management server and the conversation key, and the group management server holds its own encryption key and the shared encryption key of the group. Then, the process attempting to join the group sends an authentication information request message to the authentication server, and the authentication server receiving this message, when authenticating the process, the conversation key encrypted with the encryption key of the process and the group management server. The process that sent the authentication information delivery message including the conversation key encrypted with the encryption key of Application to join by decrypting the conversation key with the encryption key, encrypting at least one of the information indicating the own process and the information indicating the group to be joined with the conversation key, and adding the conversation key encrypted with the encryption key of the group management server The message is sent to the group management server, and the group management server that receives the message decrypts the conversation key with its own encryption key, acquires the information indicating the process and the information indicating the group to which the user wants to join by using the conversation key, and then the conversation. A shared cryptographic key distribution message including the shared cryptographic key of the group encrypted with a key is transmitted, and the process receiving the message uses the conversation key to obtain the shared cryptographic key and uses the shared cryptographic key to group the group. A broadcast encryption communication method, characterized in that broadcast encryption communication is performed in-house. 2. The broadcast encryption communication method according to claim 1, wherein the group management server generates a new shared encryption key at a predetermined timing and encrypts the new shared encryption key with the previous shared encryption key. A shared encryption key change broadcast notification message including an encryption key is created and broadcast to processes belonging to the group, and the process uses the shared encryption key from the received shared encryption key change broadcast notification message to create a new message. A broadcast encryption communication method characterized by acquiring a shared encryption key and then performing broadcast encryption communication using a new shared encryption key. 3. The broadcast encryption communication method according to claim 1, wherein the group management server generates a new shared encryption key every predetermined period and continuously joins a process belonging to a group. The process that broadcasts the inquiry message and returns the continuous join response message to the process sends a shared encryption key change individual notification message including the new shared encryption key encrypted with the conversation key with the process. The process that created and sent and did not return the continuous join response message is deleted from the group, and the process acquires a new shared cryptographic key using the conversation key from the received shared cryptographic key change individual notification message,
After that, the broadcast encryption communication method is characterized by performing the broadcast encryption communication using a new shared encryption key. 4. A plurality of computers, an authentication server, and a group management server are connected to a network, and a process running on the computer holds its own encryption key and sends an authentication information request message to the authentication server. Authentication information request message transmitting means, a conversation key acquisition means for acquiring a conversation key from the received authentication information delivery message using its own encryption key, and information indicating the own process or information indicating a group to which the conversation key belongs From at least one of the group encryption server and the encryption key of the group management server, and adds a conversation key to create a subscription request message and sends it to the group management server; A shared encryption key acquisition unit that acquires the shared encryption key using the conversation key, and the shared encryption key And a broadcast encrypted communication message transmitting means for creating and transmitting a broadcast encrypted communication message, and a broadcast data acquisition means for acquiring broadcast data from the received broadcast encrypted communication message using the shared encryption key. The authentication server holds the encryption key of each process and the encryption key and conversation key of the group management server, and when authenticating the process requesting the authentication information, the conversation key and group encrypted with the encryption key of the process. The group management server includes an authentication information delivery message sending unit that creates and sends an authentication information delivery message including a conversation key encrypted with the encryption key of the management server, wherein the group management server stores the own encryption key and the shared encryption key of each group. Conversation key acquisition means for holding and holding the received subscription request message with its own encryption key to obtain a conversation key, and the conversation And a shared information of the group encrypted with the conversation key when permitting the process to join the group. A broadcast encryption communication system, comprising: a shared encryption key distribution message transmitting means for creating and transmitting a shared encryption key distribution message including a key. 5. The broadcast encryption communication system according to claim 4, wherein the group management server generates a new shared encryption key at a predetermined timing and encrypts the new shared encryption key with the previous shared encryption key. A shared encryption key update control means for creating and transmitting a shared encryption key change broadcast notification message including an encryption key is provided, and the process uses the shared encryption key from the received shared encryption key change broadcast notification message to update a new shared encryption key. A shared encryption communication system comprising: a shared encryption key updating unit that acquires a new shared encryption key and uses the new shared encryption key as a subsequent shared encryption key. 6. The broadcast encryption communication system according to claim 4, wherein the group management server generates a new shared encryption key every predetermined period and continuously joins a process belonging to a group. The process that broadcasts the inquiry message and returns the continuous join response message to it receives the shared encryption key change individual notification message containing the new shared encryption key encrypted with the conversation key with the process. The process that created and transmitted and did not return the continuous join response message comprises group member confirmation control means for deleting from the group, and the process uses the conversation key from the received shared encryption key change individual notification message to create a new shared key. Get the encryption key,
A broadcast encryption communication system, comprising: a shared encryption key updating unit that uses the new shared encryption key as a subsequent shared encryption key.