JP4153375B2 - Common key synchronization method and common key synchronization apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for matching these common keys when data encrypted using the common key is decrypted using the common key.
[0002]
[Prior art]
The common key cryptosystem is a technique for encrypting data on the transmission side and decrypting data on the reception side using a common encryption key, and has been used for a long time. The common key cryptosystem has advantages such as a higher processing speed than the public key cryptosystem.
The update of the common key is necessary to increase the confidentiality of the data. However, when encrypted data is transmitted during the common key update process, the common key does not match between the transmitting terminal device and the receiving terminal device, and the receiving terminal device cannot decrypt the original data. There is a case. For example, the receiving side terminal device updates the common key in response to the key update request packet from the transmitting side terminal device, and then sends a key update confirmation packet to the transmitting side terminal device to notify that the common key has been updated. Send. Before receiving the key update confirmation packet, the transmission-side terminal device transmits data that has been encrypted using the old common key (the current common key for the transmission side). In this case, a common key mismatch occurs, and the original data cannot be decrypted by the receiving terminal device.
[0003]
In order to solve this type of problem, for example, in transmission / reception of video data, a plurality of common keys to which indexes are assigned in advance are stored on the transmission side and the reception side, and the index is changed when the common key is changed. Has been proposed (see Patent Document 1, for example).
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-247542
[0004]
[Problems to be solved by the invention]
However, in the conventional technique described above, the common key used for encryption can only be selected from the common keys stored in advance. For this reason, confidentiality will become low by long-term use.
[0005]
An object of the present invention is to provide a common key synchronization method and a common key synchronization system that can normally decrypt encrypted transmission data even when the common key does not match between the transmission side and the reception side.
Another object of the present invention is to provide a common key synchronization method and a common key synchronization system that can maintain the confidentiality of data for a long period of time.
[0006]
[Means for Solving the Problems]
In the common key synchronization method according to claim 1 and the common key synchronization system according to claim 6, the common key and the common key are stored in the common database and the common database in the reception side database of the transmission side terminal device. And key identification information for identification are registered.
At the time of updating the common key, the transmission side terminal device generates new key identification information corresponding to the newly generated common key, and transmits this key identification information to the reception side terminal device. For example, the key identification information is generated by the identification information adding unit and transmitted to the receiving terminal device by the transmission unit. Further, the transmission side terminal device generates a new common key based on the key generation information, and registers the new common key and the new key identification information in the transmission side database. For example, the common key is generated by the transmission side common key generation unit. The common key and key identification information are registered in the transmission side database by the transmission side registration unit.
[0007]
When receiving the new key identification information from the transmitting terminal device, the receiving side terminal device generates a new common key based on the key generation information in order to update the common key. The receiving terminal device registers a new common key and new key identification information in the receiving database. For example, the key identification information is received by the reception unit, the new common key is generated by the reception side common key generation unit, and the common key and the key identification information are registered in the reception side database by the reception side registration unit.
[0008]
Thus, since the common key can be generated sequentially, the confidentiality of the data can be maintained for a long time.
At the time of data transmission, the transmission side terminal device encrypts transmission data using a new common key extracted from the transmission side database. The transmission-side terminal device adds the key identification information corresponding to the new common key extracted from the transmission-side database to the encrypted transmission data. Then, the encrypted transmission data to which the key identification information is added is transmitted to the receiving terminal device. For example, the transmission data is encrypted by the data encryption unit. The key identification information is added by the identification information adding unit. The encrypted transmission data is transmitted by the transmission unit.
[0009]
The reception side terminal device that has received the transmission data searches the reception side database using the key identification information added to the encrypted transmission data, and extracts the common key corresponding to this key identification information. Then, the encrypted transmission data is decrypted using the extracted common key. For example, retrieval of the receiving side database and data decoding are performed by the data decoding unit.
[0010]
In this way, when the data encrypted with the common key at the transmitting terminal device is decrypted with the common key at the receiving terminal device, it is generated individually for each common key together with the encrypted data. By transmitting the key identification information, the encrypted transmission data can be normally decrypted even when the current common key does not match. For example, when the transmitting terminal device transmits data encrypted using an old common key and the receiving terminal device receives the data after updating the common key, the difference in the version of the common key is determined by the key identification information. Can be determined. The receiving side database of the receiving side terminal device holds an old common key and key identification information corresponding to this common key. For this reason, the receiving side terminal device can extract the old common key corresponding to the key identification information from the receiving side database and normally decrypt the data using this common key.
[0011]
In the common key synchronization method according to claim 2 and the common key synchronization system according to claim 7, the transmission side terminal device encrypts the transmission data in units of packets, and the key identification information is added to a header added to the encrypted packet. include. For this reason, the key identification information can be easily and reliably transmitted to the receiving terminal device together with the encrypted data during packet communication. In the common key synchronization method of claim 3 and the common key synchronization system of claim 8, the key identification information is a sequence number included in the header and uniquely assigned to each packet. That is, a part of the existing information in the header is regarded as key identification information. A group of key identification information indicating a plurality of sequence numbers sequentially assigned to each packet is registered as key identification information in the transmission side database and the reception side database. In order to associate a plurality of sequence numbers with one key identification information, a dedicated field for storing the key identification information does not need to be provided in the header. Since a conventional header format can be used as it is, the common key can be reliably matched with minimal system changes.
[0012]
In the common key synchronization method of claim 4 and the common key synchronization system of claim 9, the receiving database stores the newest common key among the registered common keys as the working common key. The receiving-side terminal device uses the new common key generated corresponding to the new key identification information sent from the transmitting-side terminal device as the next common key that is temporarily prohibited from being used together with the new key identification information. Register in the receiver database. When receiving the encrypted transmission data from the transmission side terminal device, the reception side terminal device searches the reception side database using the key identification information added to the encrypted transmission data. When this key identification information corresponds to the next common key, the current common key is changed to the old common key, the next common key is changed to the current common key, and the transmission data is a new current common key. And decrypted. For example, the state of the common key is changed by the common key changing unit.
[0013]
When receiving data encrypted using a new common key, by setting the common key to a new common key for the first time, due to a communication failure between the transmitting terminal device and the receiving terminal device, etc. Even when confirmation of the start of use of a new common key cannot be performed normally, transmission data can be decrypted normally.
In the common key synchronization method of claim 5 and the common key synchronization system of claim 10, the transmission side database and the reception side database store the common key and key identification information for each destination address. The common key and key identification information are generated and registered for each destination address. Therefore, the transmitting terminal device can transmit encrypted data to each of the plurality of receiving terminal devices. The receiving side terminal device can decode data from a plurality of transmitting side terminal devices, respectively.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an overview of the first embodiment of the present invention.
The common key synchronization method and the common key synchronization system of the present invention are realized by the transmission-side terminal device 100 and the reception-side terminal device 200 that are wirelessly connected to a communication network. The reception-side terminal device 200 may be connected by a single device or a plurality of devices. The communication network may be a wide area network or a local area network.
[0015]
The transmission-side terminal device 100 and the reception-side terminal device 200 are configured by mobile terminals, personal computers, or workstations. Note that the mobile terminal, personal computer, or workstation may have one of the functions of the transmission-side terminal device 100 and the reception-side terminal device 200, and functions of both the transmission-side terminal device 100 and the reception-side terminal device 200. You may have.
[0016]
The transmission-side terminal device 100 includes a key update unit 110, a transmission-side database 120, an encryption unit 130, and a transmission / reception unit 140. The key update unit 110 operates when the common key is updated. As shown in FIG. 4 described later, the transmission database 120 holds destination address information AI, a registration status flag FLG, a common key KEY, and key identification information KII. The encryption unit 130 operates to encrypt this data when transmitting the data. The transmission / reception unit 140 transmits / receives an update packet when the common key is updated, and transmits encrypted data.
[0017]
The reception-side terminal device 200 includes a key update unit 210, a reception-side database 220, a decryption unit 230, and a transmission / reception unit 240. The key update unit 210 operates when the common key is updated. Similar to the transmission side database 120, the reception side database 220 holds destination address information AI, registration state FLG, common key KEY, and key identification information KII. The decryption unit 230 operates to decrypt this data when receiving the data. The transmission / reception unit 240 transmits / receives an update packet when the common key is updated, and receives encrypted data.
[0018]
FIG. 2 shows details of the transmitting terminal device 100 shown in FIG.
The key update unit 110 includes an update control unit 111, an update packet reception unit 112, an update packet transmission unit 113, an identification information addition unit 114, and a common key generation unit 115 (transmission side common key generation unit). The encryption unit 130 includes a data encryption unit 131 and an identification information addition unit 132. The transmission / reception unit 140 includes a packet reception unit 141 and a packet transmission unit 142.
[0019]
When the update control unit 111 receives the key update request UPREQ from the data encryption unit 131, the update control unit 111 updates the common key for the destination address information AI received together with the key update request UPREQ. Start control. Here, the destination address information AI is a destination address individually assigned to the receiving terminal device 200 shown in FIG.
[0020]
In the common key update process, first, the update control unit 111 outputs destination address information AI (for example, destination address # 4 shown in FIG. 4) to the identification information adding unit 114. The identification information adding unit 114 sends the destination address information AI to the transmission side database 120, and the key identification information KII (for example, sequence number # 15 shown in FIG. 4) corresponding to the current common key (for example, 1499baef shown in FIG. 4). ) To get.
[0021]
The identification information adding unit 114 generates new key identification information KII (for example, # 16 obtained by incrementing # 15 by 1) different from the key identification information KII (# 15) of the current common key, and this key identification information The KII is transferred to the update packet transmitter 113 together with the destination address information AI and other information necessary for key update (such as authentication information). Further, the identification information adding unit 114 transfers the new key identification information KII (# 16) to the update control unit 111.
[0022]
In response to the reception of the new key identification information KII (# 16), the update packet transmission unit 113 generates key generation information KGI (S) for generating a new common key. The update packet transmission unit 113 transfers the key generation information KGI (S) to the update control unit 111. The update packet transmitter 113 transmits the update request packet UPP1 including the destination address information AI to the receiving terminal device 200 (destination address # 4) corresponding to the destination address information AI via the packet transmitter 142. The update request packet UPP1 is a packet for notifying the receiving side terminal device 200 of the common key update process.
[0023]
Thereafter, the update packet receiving unit 112 receives the update request response packet UPP2 from the receiving side terminal device 200 corresponding to the destination address information AI via the packet receiving unit 141. The update request response packet UPP2 is a packet for confirming that the update request packet UPP1 has been received by the reception-side terminal device 200 and the common key update process has started.
[0024]
The update packet receiving unit 112 notifies the update packet transmitting unit 113 that the update request response packet UPP2 including the destination address information AI has been received. In response to the reception of the update request response packet UPP2, the update packet transmitter 113 sends the update information packet UPP3 including the destination address information AI and the key generation information KGI (S) to the destination address information AI via the packet transmitter 142. To the receiving side terminal device 200 corresponding to. The update information packet UPP3 is a packet for sending data necessary for updating the common key and instructing the update of the common key. As shown in FIG. 3 described later, the receiving side terminal device 200 corresponding to the destination address information AI receives the key generation information KGI (S) and the key generation information generated by itself when the update information packet UPP3 is received. A new common key KEY is generated based on KGI (R), and this new common key KEY is used as a working key.
[0025]
The update packet receiving unit 112 receives the update confirmation packet UPP4 including the destination address information AI and the key generation information KGI (R) from the receiving terminal device 200 corresponding to the destination address information AI via the packet receiving unit 141. The update confirmation packet UPP4 is a packet for confirming that the receiving side terminal device 200 has completed the update of the common key. The update packet receiving unit 112 transfers the received key generation information KGI (R) to the update control unit 111. The update control unit 111 outputs the received key generation information KGI (S) and KGI (R) to the common key generation unit 115 together with the destination address information AI and the new key identification information KII.
[0026]
The common key generation unit 115 generates a new common key KEY based on the key generation information KGI (S) and KGI (R). The common key generation unit 115 registers the generated common key KEY in the transmission side database 120 together with the destination address information AI and the new key identification information KII. Thus, the common key generation unit 115 also operates as a transmission side registration unit that registers a new common key KEY and new key identification information KII in the transmission side database 120. By registering the new common key KEY in the transmission side database 120, the common key KEY that was in use before registration is retained as the old common key, and the registered new common key KEY becomes the current common key. .
[0027]
On the other hand, at the time of data transmission, the data encryption unit 131 receives destination address information AI and packet data (transmission data). The data encryption unit 131 sends the received destination address information AI to the transmission-side database 120, and acquires the working common key KEY corresponding to the destination address information AI and the key identification information KII corresponding to the common key KEY. The data encryption unit 131 encrypts the packet data using the acquired common key KEY, and transfers the encrypted packet data CD to the identification information adding unit 132 together with the key identification information KII. The identification information adding unit 132 writes the key identification information KII in the header of the encrypted packet data CD, and transmits the key identification information KII to the reception side terminal device 200 via the packet transmission unit 142 as an encrypted packet CP.
[0028]
FIG. 3 shows details of the receiving-side terminal device 200 shown in FIG.
The key update unit 210 includes an update control unit 211, an update packet reception unit 212, an update packet transmission unit 213, and a common key generation unit 215 (reception side common key generation unit). The decryption unit 230 has a data decryption unit 231. The transmission / reception unit 240 includes a packet reception unit 241 and a packet transmission unit 242.
[0029]
When the update packet reception unit 212 receives the update request packet UPP1 from the transmission-side terminal device 100 via the packet reception unit 241, the update packet reception unit 212 notifies the update packet transmission unit 213 of the information. When the common key can be updated, the update packet transmission unit 213 transmits an update request response packet UPP2 to the transmission-side terminal device 100 via the packet transmission unit 242 in response to the update request packet UPP1.
[0030]
Thereafter, when the update packet reception unit 212 receives the update information packet UPP3 including the key generation information KGI (S) and the new key identification information KII from the transmission side terminal device 100 via the packet reception unit 241, And the transmission source information AI indicating the transmission side terminal device 100 are transferred to the update control unit 211 together with the key update request UPREQ. Also, the update packet receiving unit 212 notifies the update packet transmitting unit 213 that the update information packet UPP3 has been received.
[0031]
The update packet transmitter 213 generates key generation information KGI (R) in response to receiving the update information packet UPP3. The update packet transmission unit 213 transfers the generated key generation information KGI (R) to the update control unit 211.
The update control unit 211 outputs the received key generation information KGI (S) and KGI (R) to the common key generation unit 215 together with the transmission source information AI and the new key identification information KII. The common key generation unit 215 generates a new common key KEY based on the key generation information KGI (S) and KGI (R). The common key generation unit 215 registers the generated common key KEY together with the transmission source information AI and the new key identification information KII in the reception-side database 220. As described above, the common key generation unit 215 also operates as a reception side registration unit that registers a new common key KEY and new key identification information KII in the reception side database 220. By registering the new common key KEY in the receiving side database 220, the common key KEY that has been used before registration is retained as the old common key, and the registered new common key KEY becomes the current common key. .
[0032]
Thereafter, the update packet transmission unit 213 transmits the update confirmation packet UPP4 including the key generation information KGI (R) to the transmission-side terminal device 100 via the packet transmission unit 242. When receiving data, the data decryption unit 231 receives packet data (transmission data) including transmission source information AI and key identification information KII in the header. The data decryption unit 231 sends the received transmission source information AI and key identification information KII to the reception-side database 220, and acquires the working common key KEY corresponding to the transmission source information AI and the key identification information KII. The data decryption unit 231 decrypts the packet data using the acquired common key KEY.
[0033]
FIG. 4 shows details of the transmission-side database 120 shown in FIG.
The transmission database 120 has four areas for storing the registration status flag FLG, the key identification information KII, and the common key KEY for each destination address information AI. The common key KEY corresponding to “0” of the registration status flag FLG indicates the current use, and the common key KEY corresponding to “1” of the registration status flag FLG indicates that the version is old. For example, in the figure, the working common key KEY corresponding to the destination address information AI = # 4 is 1499baef in hexadecimal, and the key identification information KII (sequence number) corresponding to this common key KEY is # 15. .
[0034]
The data structure of the reception side database 220 is the same as the data structure of the transmission side database 120 except that the destination address information AI is replaced with the transmission source information AI.
FIG. 5 shows a format of a packet for transmitting data in the first embodiment.
[0035]
The packet is composed of a payload (encrypted payload) obtained by encrypting transmission data, and a header including destination address information AI and key identification information KII.
FIG. 6 shows an example of registering / updating a new common key in the transmission side database 120 in the first embodiment. Here, updating of the common key KEY corresponding to destination address information AI # 4 will be described. The left side in the figure shows the state before update, and the right side shows the state after update.
[0036]
Before the update, the common key KEY (1499baef) corresponding to the registration status flag FLG = “0” is the current key. The key identification information KII of this common key KEY is # 15. Up to four common keys KEY can be registered for each destination address information AI. Since the four common keys KEY are already registered, the common key KEY (2cc34e87) corresponding to the smallest key identification information KII (# 12) is deleted by the update process of the common key KEY. Next, a new common key KEY (7ef6ca25) is written together with new key identification information KII (# 16). Then, the registration status flag FLG corresponding to the common key KEY (1499baef) is rewritten to “1”, and the registration status flag FLG corresponding to the common key KEY (7ef6ca25) is rewritten to “0”. That is, the common key KEY (1499baef) used until immediately before becomes the old common key, and the newly registered common key KEY (7ef6ca25) becomes the current common key.
[0037]
Note that the update processing of the reception side database 220 is the same as the update processing of the transmission side database 120 except that the destination address information AI is replaced with the transmission source information AI. By registering the newly generated common key KEY in the transmission side database 120 and the reception side database 220 respectively, the number of the common key KEY can be unlimited because the common key KEY is updated. For this reason, even when this system is used for a long time, it is possible to prevent the confidentiality of data from being lowered. Further, by using four areas for each destination address information AI, the capacity of the transmission side database 120 and the reception side database 220 can be minimized.
[0038]
FIG. 7 shows an example of packet communication before and after the update of the common key and the update in the first embodiment. In the figure, a packet for update processing is indicated by a broken line, and a packet of normal data is indicated by a solid line.
In this example, the wireless terminal device WT1 requests the wireless terminal device WT2 to update the common key KEY. The wireless terminal devices WT1 and WT2 correspond to the transmitting terminal device 100 and the receiving terminal device 200 shown in FIG. However, the wireless terminal device WT1 also has a packet reception function, and the wireless terminal device WT2 also has a packet transmission function.
[0039]
First, the wireless terminal device WT1 transmits an update request packet UPP1 to the wireless terminal device WT2 in order to update the common key KEY. The wireless terminal device WT2 returns an update request response packet UPP2 in response to the update request packet UPP1. In response to the update request response packet UPP2, the wireless terminal device WT1 transmits an update information packet UPP3 to the wireless terminal device WT2.
At this point, the current common key KEY is 1499baef (key identification information KII = # 15) for both the wireless terminal devices WT1 and WT2. Therefore, normal packets CP1 and CP2 transmitted / received between the wireless terminal devices WT1 and WT2 can be normally decoded.
[0040]
Next, the wireless terminal device WT2 receives the update information packet UPP3 and updates the common key KEY from 1499baef to 7ef6ca25 (key identification information KII = # 16). Then, the wireless terminal device WT2 transmits an update confirmation packet UPP4 to the wireless terminal device WT1. In response to the update confirmation packet UPP4, the wireless terminal device WT1 updates the common key KEY from 1499baef to 7ef6ca25 (key identification information KII = # 16).
[0041]
Here, there is a time lag between the wireless terminal device WT2 receiving the update information packet UPP3 and updating the common key KEY until the wireless terminal device WT1 receives the update confirmation packet UPP4 and updates the common key KEY. is there. Therefore, when the wireless terminal device WT2 receives the packet CP3 encrypted by the wireless terminal device WT1 using the common key KEY (1499baef, key identification information KII = # 15), the current usage of the wireless terminal device WT2 The common key KEY may have been changed to 7ef6ca25 (key identification information KII is # 16). Conventionally, this packet CP3 cannot be decoded, and normal communication is hindered.
[0042]
In the present invention, the wireless terminal device WT2 extracts the common key KEY (1499baef) corresponding to the key identification information KII (# 15) included in the header of the encrypted packet CP3 from the reception-side database 220, thereby Encrypted packet CP3 can be decrypted even when KEY is not synchronized (matched).
After the wireless terminal device WT1 updates the common key KEY, the encrypted packets CP4, CP5, CP6 are successfully decrypted and the normal communication because the common key KEY matches between the wireless terminal devices WT1, WT2. Is maintained.
[0043]
As described above, in the first embodiment, since the number of updated common key KEYs can be unlimited, the confidentiality of data can be maintained even when this system is used for a long time.
In the update process of the common key KEY, the key identification information KII corresponding to the newly generated common key KEY is transmitted from the transmission side terminal device 100 to the reception side terminal device 200, and this key identification information KII together with the new common key KEY is transmitted. Are stored in the transmission side database 120 and the reception side database 220. For this reason, when the data received by the receiving terminal device 200 is decrypted using the common key KEY, the difference in the version of the common key can be determined by the key identification information KII. Therefore, even when the current common key KEY does not match between the transmission-side terminal device 100 and the reception-side terminal device 200, the encrypted transmission data can be normally decrypted.
[0044]
Since the key identification information KII is included in the header added to the encrypted packet, the key identification information KII can be easily and reliably transmitted from the transmission side terminal device 100 to the reception side terminal device 200 together with the encrypted data.
Since the transmission side database 120 and the reception side database 220 store the common key KEY and the key identification information KII for each destination address information AI, the transmission side terminal device 100 encrypts each of the plurality of reception side terminal devices 200. Data can be sent. The receiving terminal device 200 can decode data from the plurality of transmitting terminal devices 100, respectively.
[0045]
FIG. 8 shows a second embodiment of the present invention. The same elements as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
In this embodiment, an example is shown in which the present invention is applied to a wireless multi-hop network having a base station AP and a plurality of wireless terminal devices WT1-WT5. The base station AP and the wireless terminal devices WT1 to WT5 have the functions of the transmission-side terminal device 100 and the reception-side terminal device 200 of the first embodiment described above.
[0046]
In this wireless multi-hop network, the wireless terminal device WT or the base station AP in the middle of the route has a function of relaying packets. For this reason, a plurality of paths can be taken from the transmission source to the reception destination. For example, when communicating from the wireless terminal device WT2 to the wireless terminal device WT4, the route ch1 via the wireless terminal device WT1 and the base station AP, the route ch2 via the wireless terminal device WT1, WT3, the wireless terminal devices WT1, WT3, It is assumed that there are three routes of route ch3 passing through WT5.
[0047]
FIG. 9 illustrates an example of packet communication between the wireless terminal devices WT2 and WT4 in the second embodiment before and after the update of the common key KEY. In this example, the wireless terminal device WT2 requests the wireless terminal device WT4 to update the common key KEY. Since the update packet (UPP1-UPP4) is the same as that of the first embodiment (FIG. 7), the illustration is omitted.
[0048]
In the figure, the packet propagation delay increases in the order of paths ch1, ch2, and ch3. For this reason, the slope of the arrow indicating the packet in the figure increases in the order of the routes ch1, ch2, and ch3.
When the current common key KEY is 1499baef in both the wireless terminal devices WT2 and WT4 (before the key is updated), normal packets CP1 to CP5 transmitted and received between the wireless terminal devices WT2 and WT4 can be normally decrypted. Further, when the current common key KEY is 7ef6ca25 (after the key is updated) in the wireless terminal devices WT2 and WT4, normal packets CP7 to CP8 transmitted and received between the wireless terminal devices WT2 and WT4 can be normally decrypted.
[0049]
On the other hand, when the packet CP6 encrypted by the wireless terminal device WT4 using the pre-update common key KEY (1499baef, key identification information KII = # 15) arrives at the wireless terminal device WT2, the wireless terminal device WT2 When the key KEY is updated to 7ef6ca25, the packet CP3 cannot be decrypted conventionally, and normal communication is hindered.
In the present invention, the wireless terminal device WT2 extracts the common key KEY (1499baef) corresponding to the key identification information KII (# 15) included in the header of the encrypted packet CP6 from the reception-side database 220, thereby Encrypted packet CP6 can be decrypted even when KEY is not synchronized (matched).
[0050]
As described above, also in this embodiment, the same effect as in the first embodiment described above can be obtained. Furthermore, in this embodiment, in a wireless multi-hop network that can take a plurality of communication paths, the encrypted transmission data is transmitted even when the current common key KEY does not match between the transmitting terminal device 100 and the receiving terminal device 200. Can be successfully decrypted.
[0051]
FIG. 10 shows a third embodiment of the present invention. The same elements as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
The common key synchronization method and the common key synchronization system of this embodiment are realized by a transmission-side terminal device 100A and a reception-side terminal device 200A that are wirelessly connected to a communication network. The transmission-side terminal device 100A and the reception-side terminal device 200A are configured by mobile terminals, personal computers, or workstations. Note that the mobile terminal, personal computer, or workstation may have one function of the transmission-side terminal device 100A and the reception-side terminal device 200A, and both functions of the transmission-side terminal device 100A and the reception-side terminal device 200A. You may have.
[0052]
The transmission-side terminal device 100A includes a key update unit 110A, a transmission-side database 120A, an encryption unit 130A, and a transmission / reception unit 140. The receiving side terminal device 200A includes a key updating unit 210A, a receiving side database 220A, a decrypting unit 23A0, and a transmitting / receiving unit 240.
In this embodiment, among the information included in the header of the transmission packet, for example, a sequence number is used as key identification information.
[0053]
FIG. 11 illustrates details of the transmission-side terminal device 100A illustrated in FIG.
The key update unit 110A includes an update control unit 111A, an update packet reception unit 112, an update packet transmission unit 113A, and a common key generation unit 115A. The encryption unit 130A includes an identification information extraction unit 133A and a data encryption unit 131A.
[0054]
The identification information extraction unit 133A extracts information that can be used as the key identification information KII from the header of the transmission packet during packet transmission. Specifically, the sequence number of the header is extracted as the key identification information KII. The identification information extraction unit 132A determines that the common key needs to be updated when the sequence number of the header increases by a predetermined value. That is, a predetermined number of sequence numbers that increase each time a packet is transmitted is grouped, and the common key KEY is updated each time these groups change. The identification information extraction unit 133A outputs the sequence number group corresponding to the next group together with the destination address information AI to the update control unit 111A as a new key identification information group KIIG. Here, the key identification information group KIIG may be composed of the leading key identification information KII and the final key identification information KII, or may be composed of the leading key identification information KII and the sequence number increment.
[0055]
Further, the identification information extraction unit 133A extracts the key identification information KII from the header of the packet during normal packet transmission, and outputs it to the data encryption unit 131A together with the destination address information AI. The data encryption unit 131A sends the received destination address information AI and key identification information KII to the transmission-side database 120A, and acquires the common key KEY corresponding to the destination address information AI and key identification information KII as the current key. The data encryption unit 131A encrypts the packet data using the acquired common key KEY, and transmits the encrypted packet data CP to the reception-side terminal device 200A via the packet transmission unit 142. In this embodiment, since the sequence number included in advance in the header of the packet is used as the key identification information KII, the identification information adding unit 132 of the first embodiment is not necessary.
[0056]
On the other hand, when the update control unit 111A receives the destination address information AI and the new key identification information group KIIG from the identification information extraction unit 133A, the update control unit 111A is configured to update the common key for the destination address information AI as a whole. Control of the operation of is started. In the update process of the common key KEY in the transmission side terminal device 100A in this embodiment, the update control unit 111A directly outputs the destination address information AI and the key identification information group KIIG to the update packet transmission unit 113, and a plurality of Except for the use of a key identification information group KIIG indicating the key identification information KII, this is the same as the update process of the first embodiment.
[0057]
FIG. 12 shows details of the receiving-side terminal device 200A shown in FIG.
The key update unit 210A includes an update control unit 211A, an update packet reception unit 212A, an update packet transmission unit 213, and a common key generation unit 215A. The decryption unit 230A includes an identification information extraction unit 233A and a data decryption unit 231A.
When the identification information extraction unit 232A receives the update packet of the common key KEY from the transmission-side terminal device 100A, the identification information extraction unit 232A transfers the received update packet to the update packet reception unit 212A. In addition, when receiving normal packet data from the transmitting terminal device 100A, the identification information extraction unit 232A extracts the key identification information KII from the packet header and outputs it to the data decryption unit 231A together with the destination address information AI. .
[0058]
FIG. 13 shows details of the transmission-side database 120A shown in FIG.
The transmission database 120A has four areas for storing the registration status flag FLG, the key identification information group KIIG, and the common key KEY for each destination address information AI. The range of the key identification information KII corresponding to the common key KEY (for example, sequence number # 2001- # 3000) is stored in the area of the key identification information group KIIG. The data structure of the receiving side database 220A is the same as the data structure of the transmitting side database 120A except that the destination address information AI is replaced with the source information AI.
[0059]
FIG. 14 shows a format of a packet for transmitting data in the third embodiment.
The packet is composed of a payload (encrypted payload) obtained by encrypting transmission data, and a header including destination address information AI and key identification information KII. As described above, the key identification information KII is a header sequence number.
[0060]
FIG. 15 shows an example in which a new common key KEY is registered in the transmission database 120A in the third embodiment. Here, updating of the common key KEY corresponding to destination address information AI # 4 will be described. The left side in the figure shows the state before update, and the right side shows the state after update.
Before the update, the common key KEY (1499baef) corresponding to the registration status flag FLG = “0” is the current key. The key identification information KII of the common key KEY is any one of sequence numbers # 5001- # 6000. Up to four common keys KEY can be registered for each destination address information AI. Since the four common keys KEY have already been registered, the common key KEY (2cc34e87) corresponding to the smallest key identification information group KIIG is deleted by the update process of the common key KEY. Next, a new common key KEY (7ef6ca25) is written together with a new key identification information group KIIG (sequence number # 6001- # 7000). Then, the registration status flag FLG corresponding to the common key KEY (1499baef) is rewritten to “1”, and the registration status flag FLG corresponding to the common key KEY (7ef6ca25) is rewritten to “0”. That is, the common key KEY (1499baef) used until immediately before becomes the old common key, and the newly registered common key KEY (7ef6ca25) becomes the current key.
[0061]
Note that the update processing of the reception side database 220A is the same as the update processing of the transmission side database 120A except that the destination address information AI is replaced with the transmission source information AI.
In this embodiment, when receiving terminal device 200A receives encrypted transmission data (ordinary packet), it extracts a common key KEY corresponding to the sequence number of the header of this packet from receiving side database 220A. . Then, the transmission data is decrypted by using the common key KEY that has been extracted.
[0062]
As described above, also in this embodiment, the same effect as in the first embodiment described above can be obtained. Furthermore, in this embodiment, by using the key identification information KII as the sequence number of the header, it is not necessary to provide a dedicated field for storing the key identification information KII in the header. Since the conventional header format can be used as it is, the common key KEY can be matched with minimal system changes.
[0063]
FIG. 16 shows a fourth embodiment of the present invention. The same elements as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
In this embodiment, in the common key update process, the receiving-side terminal device 200B registers a new common key in the receiving-side database 220, and does not immediately use this common key as the current key. The receiving-side terminal apparatus 200B uses the new common key as a working common key when receiving a packet encrypted using this key. The configuration excluding the receiving terminal device 200B is the same as that of the first embodiment. The reception-side terminal device 200B includes a key update unit 210B and a decryption unit 230B instead of the key update unit 210 and the decryption unit 230 of the first embodiment.
[0064]
FIG. 17 illustrates details of the reception-side terminal device 200B illustrated in FIG.
The key update unit 210B includes an update control unit 211, an update packet reception unit 212, an update packet transmission unit 213, and a common key generation unit 215B. The decryption unit 230 includes a data decryption unit 231B.
When newly registering the destination address information AI, the common key KEY, and the key identification information KII, the common key generation unit 215B sets the registration status flag FLG to “2” instead of “0”. The common key KEY whose registration status flag FLG is set to “2” means the next common key whose use is temporarily prohibited. Other operations are the same as those of the common key generation unit 215 of the first embodiment.
[0065]
The data decryption unit 231B includes a common key change unit 233B in addition to the function of the data decryption unit 231 of the first embodiment. When the common key changing unit 233B receives the key identification information KII together with the encrypted packet, the common key changing unit 233B searches the reception-side database 220 and determines whether the registration status flag FLG corresponding to the key identification information KII is set to “2”. Check. When the registration status flag FLG is set to “2”, the common key changing unit 233B changes the registration status flag FLG of the current common key KEY from “0” to “1”, and registers the next common key KEY. The status flag FLG is changed from “2” to “0”. That is, the next common key KEY does not become the current common key KEY just by being registered, but becomes the current common key KEY when a packet encrypted with the new common key KEY is received.
[0066]
The data decryption unit 231B waits for a period during which the next common key KEY is changed to the current common key KEY, and then performs a decryption process.
FIG. 18 illustrates a key update process of the reception-side terminal device 200B according to the fourth embodiment.
In step S10, the update process of the common key is completed, and the next common key KEY and the key identification information KII corresponding to this key are registered together with the registration state flag FLG = “2”.
[0067]
In step S20, the decryption unit 230B shifts to the registration state update mode.
In step S30, the packet receiver 241 receives a packet.
In step S40, the common key changing unit 233B accesses the reception-side database 220 and determines whether or not the common key KEY corresponding to the key identification information KII added to the encrypted packet is the next common key KEY. In the case of the next common key KEY, the process proceeds to step S50. In the case of the working common key KEY, the process proceeds to step S70.
[0068]
In step S50, in order to update the registration state of the common key in the receiving side database 220, the common key changing unit 233B changes the registration state flag FLG of the current common key KEY from “0” to “1”. The registration status flag FLG of the common key KEY is changed from “2” to “0”.
In step S60, the decryption unit 230B ends the registration state update mode.
[0069]
In step S70, the data encryption unit 231 accesses the reception-side database 220, extracts the current common key KEY, and decrypts the encrypted packet.
FIG. 19 shows changes in the receiving database 220 in the common key KEY update process shown in FIG. Here, updating of the common key KEY corresponding to destination address information AI # 4 will be described. The left side in the figure shows the state before update, the center shows the state after registration as the next common key, and the right side shows the state after update of the common key.
[0070]
As described above, the new common key KEY (7ef6ca25) is registered as the next common key KEY by writing “2” in the registration status flag FLG. Thereafter, when the key identification information KII added to the encrypted packet corresponds to the next common key KEY, the registration state flag FLG of the current common key KEY (1499baef) is rewritten to “1”, and the registration state The flag FLG “2” is rewritten to “0”. In other words, the common key is updated after the packet is actually received, and the next common key KEY becomes the current common key KEY.
[0071]
FIG. 20 shows an example of common key update and packet communication before and after the update in the fourth embodiment. In the figure, a packet for update processing is indicated by a broken line, and a packet of normal data is indicated by a solid line.
In this example, the wireless terminal device WT1 requests the wireless terminal device WT2 to update the common key KEY. The wireless terminal devices WT1 and WT2 correspond to the transmitting terminal device 100 and the receiving terminal device 200B shown in FIG. However, the wireless terminal device WT1 also has a packet reception function, and the wireless terminal device WT2 also has a packet transmission function.
[0072]
In the common key update process, an update request packet is transmitted from the wireless terminal device WT1, and an update request response packet is transmitted from the wireless terminal device WT2. Thereafter, the wireless terminal device WT2 receives the update information packet UPP3 from the wireless terminal device WT1, generates a new common key KEY, and registers it as the next common key KEY. The wireless terminal device WT2 transmits an update confirmation packet UPP4 to the wireless terminal device WT1.
[0073]
However, due to the loss of the update confirmation packet UPP4, the wireless terminal device WT1 cannot receive the update confirmation packet UPP4. For this reason, the wireless terminal device WT1 transmits the update information packet UPP3 ′ again. Upon receiving the update information packet UPP3 ′, the wireless terminal device WT2 transmits an update confirmation packet UPP4 to the wireless terminal device WT1. The wireless terminal device WT1 updates the common key KEY (7ef6ca25) in response to the update confirmation packet UPP4. At this point, the wireless terminal device WT2 has not yet updated the common key. The current common key of the wireless terminal device WT2 is 1499baef. The common key (7ef6ca25) is held as the next common key KEY in the receiving-side database 220.
[0074]
During the update process of the common key KEY, all packets CP1-CP5 encrypted using the common key KEY (1499baef) corresponding to the key identification information KII (# 15) Decrypted.
The wireless terminal device WT2 transmits the packet CP6 encrypted with the common key KEY (1499baef) corresponding to the key identification information KII (# 15) together with the key identification information KII. The wireless terminal device WT1 searches the transmission side database 120 using the key identification information KII (# 15), and normally decrypts the packet using the corresponding old encryption key KEY (1499baef).
[0075]
The wireless terminal device WT1 transmits the packet CP7 encrypted with the new common key KEY (7ef6ca25) corresponding to the key identification information KII (# 16) together with the key identification information KII. The wireless terminal device WT2 searches the receiving database 220 using the key identification information KII (# 16), and rewrites the corresponding registration status flag FLG from “2” to “0”, so that the next common key KEY (7ef6ca25 ) Is set as the working common key KEY. Then, the wireless terminal device WT2 normally decrypts the packet using the common key KEY (7ef6ca25).
[0076]
The subsequent packets CP8 and CP9 are encrypted and decrypted using the same common key KEY (7ef6ca25).
FIG. 21 shows an example of the common key update before application of the present invention and packet communication before and after the update.
Before the application of the present invention, the wireless terminal device WT2 updates the common key KEY in response to the first update information packet UPP3. For this reason, the packets CP3-CP5 cannot synchronize the common key KEY and cannot normally decrypt the packet data.
[0077]
As described above, also in this embodiment, the same effect as in the first embodiment described above can be obtained. Further, in this embodiment, the receiving side terminal device 200B is temporarily prohibited from using the new common key KEY generated corresponding to the new key identification information KII sent from the transmitting side terminal device 100. Register the next common key in the receiving database 220 and use the next common key KEY when it is determined based on the key identification information KII that the encrypted data has been received using the new common key KEY. Set to the common key. For this reason, transmission data can be normally decrypted even when confirmation of the start of use of a new common key KEY cannot be normally performed due to a communication failure between the transmitting terminal device 100 and the receiving terminal device 200B.
[0078]
FIG. 22 shows a fifth embodiment of the present invention. The same elements as those described in the fourth embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
In this embodiment, as in the second embodiment, an example in which the present invention is applied to a wireless multi-hop network having a base station AP and a plurality of wireless terminal devices WT1-WT5 is shown. The base station AP and the wireless terminal devices WT1 to WT5 have the functions of the transmission-side terminal device 100 and the reception-side terminal device 200B of the fourth embodiment described above.
[0079]
In this example, the base station AP and all the wireless terminal devices WT1-WT5 under its control have a common key NK (hereinafter referred to as a network key NK). The network key NK is updated from the base station AP to all the wireless terminal devices WT1-WT5. At this time, the base station AP encrypts a new network key NK with a different encryption key for each wireless terminal device WT1-WT5, and individually transmits the encrypted network key NK to each wireless terminal device WT1-WT5. The wireless terminal devices WT1-WT5 store the new network key NK as the next network key NK.
[0080]
After the new network key NK is transmitted to all the wireless terminal devices WT1-WT5, the base station AP transmits an update timing information packet by broadcast, and notifies the start of use of the new network key NK. When receiving the update timing information packet, the wireless terminal devices WT1-WT5 set the stored next network key NK as the current network key NK. Alternatively, when the wireless terminal devices WT1-WT5 determine that the data encrypted with the new network key NK has been received based on the key identification information KII, the next network key NK is used as the current network key NK. Set.
[0081]
FIG. 23 shows an example of packet communication before and after the network key NK is updated in the fifth embodiment. In this example, the wireless terminal devices WT1 and WT2 store the new network key NK as the next network key NK.
The base station AP receives the update timing information packet of the network key NK from the server, and transmits the update timing information packet to the radio terminal device WT1 directly below, as indicated by a broken line in the figure. Upon receiving the update timing information packet, the base station AP and the wireless terminal device WT1 set the next network key NK as the current network key NK.
[0082]
The wireless terminal device WT1 transmits an update timing information packet to the wireless terminal device WT2 (WT3) immediately below. However, this packet is lost before arriving at the wireless terminal device WT2. For this reason, the wireless terminal device WT2 cannot update the network key NK.
The packet CP1 transmitted from the wireless terminal device WT1 to the wireless terminal device WT2 is encrypted using the old network key NK (1499baef) and transmitted together with the key identification information KII (# 15). The wireless terminal device WT2 can normally restore the packet CP1 because the network key NK is not updated.
[0083]
The packet CP2 transmitted from the wireless terminal device WT1 to the base station AP is encrypted using the old network key NK (1499baef) and transmitted together with the key identification information KII (# 15). The base station AP retrieves the old network key NK (1499baef) from the receiving database 220 using the key identification information KII, and normally decrypts the packet CP2 using this key.
[0084]
The packet CP3 transmitted from the wireless terminal device WT1 to the wireless terminal device WT2 is encrypted using the new network key NK (7ef6ca25) and transmitted together with the key identification information KII (# 16). As in the fourth embodiment, the wireless terminal device WT2 uses the next network key NK (7ef6ca25) as the current network key NK when receiving the packet CP3, and normally restores the packet CP3 using this network key NK. To do.
[0085]
The packet CP4 transmitted from the wireless terminal device WT2 to the wireless terminal device WT1 is encrypted using the new network key NK (7ef6ca25) and transmitted together with the key identification information KII (# 16). Since the wireless terminal device WT1 has already updated the network key NK, the packet CP4 can be restored normally.
As described above, also in this embodiment, the same effects as those of the first and fourth embodiments described above can be obtained. Furthermore, in this embodiment, in a wireless multi-hop network that can take a plurality of communication paths, encrypted transmission data can be normally decrypted even when the network key NK cannot be updated simultaneously.
[0086]
FIG. 24 shows a sixth embodiment of the present invention. The same elements as those described in the first, third and fourth embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.
The common key synchronization method and the common key synchronization system of this embodiment are realized by a transmission-side terminal device 100A and a reception-side terminal device 200C that are wirelessly connected to a communication network. The transmitting terminal device 100A and the receiving terminal device 200C are configured by a mobile terminal, a personal computer, or a workstation. Note that the mobile terminal, personal computer, or workstation may have one function of the transmission-side terminal device 100A and the reception-side terminal device 200C, and both functions of the transmission-side terminal device 100A and the reception-side terminal device 200C. You may have.
[0087]
FIG. 25 illustrates details of the reception-side terminal device 200C illustrated in FIG.
The decoding unit 230C of the receiving side terminal device 200C replaces the data decoding unit 231A of the decoding unit 230A of the receiving side terminal device 200A of the third embodiment (FIG. 12) with the decoding of the fourth embodiment (FIG. 17). It is configured in place of the data decoding unit 231B of the conversion unit 230B. The configuration excluding the decoding unit 230C is the same as that of the reception-side terminal device 200A of the third embodiment.
[0088]
In this embodiment, the key identification information KII is registered in the receiving database 220A as the key identification information group KIIG. The common key KEY is first registered in the receiver database 220A as the next common key KEY (registration status flag FLG = “2”). Then, when a packet encrypted using the next common key KEY is received, the next common key KEY is set to the current common key KEY.
[0089]
FIG. 26 shows changes in the receiving-side database 220C in the common key KEY update process.
The receiving side database 220C is formed by changing the area for registering the key identification information KII in the receiving side database 220 of the fourth embodiment (FIG. 19) to the area for registering the key identification information group KIIG. Here, updating of the common key KEY corresponding to destination address information AI # 4 will be described. The left side in the figure shows the state before update, the center shows the state after registration as the next common key, and the right side shows the state after update of the common key.
[0090]
The new common key KEY (7ef6ca25) is registered as the next common key KEY by writing "2" in the registration status flag FLG. Thereafter, when the key identification information KII added to the encrypted packet is included in the key identification information group KIIG corresponding to the next common key KEY, the registration status flag FLG of the current common key KEY (1499baef) is " The registration status flag FLG “2” is rewritten to “0”. That is, the common key is updated, and the next common key KEY becomes the current common key KEY.
[0091]
As described above, also in this embodiment, the same effects as those of the first, third, and fourth embodiments described above can be obtained.
In the above-described embodiment, an example in which the present invention is applied to a terminal device of a wireless communication network has been described. However, the present invention is not limited to this embodiment. For example, the present invention may be applied to a terminal device of a wired communication network.
[0092]
【The invention's effect】
In the common key synchronization method of claim 1 and the common key synchronization system of claim 6, since the common key can be generated sequentially, the confidentiality of the data can be maintained for a long period of time. Even when the current common key does not match between the transmitting terminal device and the receiving terminal device, the encrypted transmission data can be normally decrypted.
[0093]
In the common key synchronization method of claim 2 and the common key synchronization system of claim 7, the key identification information can be easily and reliably transmitted to the receiving terminal device together with the encrypted data during packet communication.
In the common key synchronization method according to claim 3 and the common key synchronization system according to claim 8, since a conventional header format can be used as it is, the common key can be surely matched by minimizing system changes. .
[0094]
In the common key synchronization method according to claim 4 and the common key synchronization system according to claim 9, when the start of use of a new common key cannot be normally confirmed due to a communication failure between the transmission side terminal device and the reception side terminal device, or the like. The transmission data can be normally decoded.
In the common key synchronization method according to claim 5 and the common key synchronization system according to claim 10, the transmitting side terminal device can transmit encrypted data to each of the plurality of receiving side terminal devices. The receiving side terminal device can decode data from a plurality of transmitting side terminal devices, respectively.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of the present invention.
FIG. 2 is a block diagram showing details of a transmission side terminal device 100 shown in FIG.
FIG. 3 is a block diagram showing details of the receiving terminal device 200 shown in FIG. 1;
FIG. 4 is an explanatory diagram showing details of a transmission side database 120 shown in FIG. 1;
FIG. 5 is an explanatory diagram showing a format of a packet for transmitting data in the first embodiment.
FIG. 6 is an explanatory diagram showing an example of registering / updating a new common key in the transmission side database 120 in the first embodiment.
FIG. 7 is an explanatory diagram illustrating an example of packet communication before and after updating a common key in the first embodiment.
FIG. 8 is a block diagram showing a second embodiment of the present invention.
FIG. 9 is an explanatory diagram illustrating an example of packet communication between the wireless terminal devices WT2 and WT4 in the second embodiment before and after updating the common key KEY.
FIG. 10 is a block diagram showing a third embodiment of the present invention.
11 is a block diagram showing details of a transmitting terminal device 100A shown in FIG.
12 is a block diagram showing details of the receiving terminal device 200A shown in FIG.
13 is an explanatory diagram showing details of the transmission database 120 shown in FIG.
FIG. 14 is an explanatory diagram showing a format of a packet for transmitting data in the third embodiment.
FIG. 15 is an explanatory diagram illustrating an example in which a new common key KEY is registered in the transmission database 120A in the third embodiment.
FIG. 16 is a block diagram showing a fourth embodiment of the present invention.
FIG. 17 is a block diagram showing details of the receiving terminal device 200A shown in FIG.
FIG. 18 is a flowchart showing a key update process of the receiving terminal device 200B according to the fourth embodiment.
FIG. 19 is an explanatory diagram showing changes in the receiving-side database 220 in the common key KEY update process shown in FIG. 18;
FIG. 20 is an explanatory diagram showing an example of packet communication before and after updating a common key in the fourth embodiment.
FIG. 21 is an explanatory diagram showing an example of a common key update before application of the present invention and packet communication before and after the update.
FIG. 22 is a block diagram showing a fifth embodiment of the present invention.
FIG. 23 is an explanatory diagram showing an example of packet communication before and after the network key NK is updated in the fifth embodiment.
FIG. 24 is a block diagram showing a sixth embodiment of the present invention.
FIG. 25 is a block diagram showing details of the receiving terminal device 200A shown in FIG. 24;
FIG. 26 is an explanatory diagram showing changes in the receiving-side database 220C in the common key KEY update process.
[Explanation of symbols]
100, 100A Transmission side terminal device
110, 110A Key update unit
111, 111A Update control unit
112 Update packet receiver
113, 113A Update packet transmitter
114 Identification information adding unit
115, 115A common key generator
120, 120A sender database
130, 130A encryption unit
131, 131A Data encryption unit
132 Identification information adding unit
133A Identification information extraction unit
140 transceiver
141 Packet receiver
142 packet transmitter
200, 200A, 200B, 200C Reception side terminal device
210, 210A, 210B Key update unit
211, 211A Update control unit
212, 212A Update packet receiver
213 Update packet transmitter
215, 215A, 215B common key generator
220, 220A Receiver database
230, 230A, 230B, 230C Decoding unit
231 and 231A data decoding unit
232A identification information extraction unit
233B Common key change part
240 transceiver
241 Packet receiver
242 Packet transmitter
AI destination address information
FLG registration status flag
KEY common key
KII key identification information

Claims (10)

There is a common key synchronization method for matching these common keys when decrypting data encrypted with a common key at a transmitting terminal device using a common key at a receiving terminal device,
When updating the common key,
In the transmission side terminal device,
Register a common key and key identification information for identifying this common key from other common keys in the sender database,
Generate new key identification information corresponding to the newly generated common key,
Sending new key identification information to the receiving terminal device;
Generate a new common key based on the key generation information,
Register a new common key and new key identification information in the sender database,
In the receiving terminal device,
Receive new key identification information,
Generate a new common key based on the key generation information,
Register a new common key and new key identification information in the receiver database,
When transmitting data, the transmitting terminal device
Encrypt transmission data using a new common key retrieved from the sender database,
The key identification information corresponding to the new common key extracted from the transmission side database is added to the encrypted transmission data,
Transmitting the encrypted transmission data to which the key identification information is added to the receiving terminal device;
The receiving terminal device
Search the receiving database using the key identification information added to the encrypted transmission data, take out the common key corresponding to this key identification information,
A common key synchronization method, comprising: decrypting transmission data encrypted using the extracted common key. The common key synchronization method according to claim 1, wherein
The transmitting terminal device
Send data is encrypted in packets,
A common key synchronization method, wherein key identification information is included in a header added to an encrypted packet. The common key synchronization method according to claim 2, wherein
Key identification information is a sequence number included in the header and uniquely assigned to each packet,
A common key synchronization method, wherein a key identification information group indicating a plurality of sequence numbers sequentially assigned to each packet is registered as key identification information in the transmission side database and the reception side database. In the symmetric key synchronization method according to claim 1 or 2,
The receiving terminal device
Storing the newest common key among the common keys registered in the receiver database as a working common key;
A new common key generated corresponding to the new key identification information sent from the transmission side terminal device is stored in the reception side database together with the new key identification information as a next common key whose use is temporarily prohibited. Register,
When receiving the encrypted transmission data from the transmission side terminal device, the reception side database is searched using the key identification information added to the encrypted transmission data, and this key identification information is used as the next common key. When it corresponds, the common key synchronization method characterized by changing the working common key to the old common key, changing the next common key to the working common key, and decrypting the transmission data using the new working common key. The common key synchronization method according to claim 1, wherein
The sender database and the receiver database store a common key and key identification information for each destination address,
A common key synchronization method, wherein generation and registration of a common key and key identification information are performed for each destination address. There is a common key synchronization system for matching these common keys when decrypting data encrypted with a common key at the transmission side terminal device using the common key at the reception side terminal device,
The transmitting terminal device
A sender database in which a common key and key identification information for identifying the common key are registered;
An identification information giving unit that generates new key identification information corresponding to the newly generated common key when the common key is updated;
A transmitting unit that transmits new key identification information or encrypted transmission data to which key identification information is added to the receiving terminal device;
A transmission side common key generation unit that generates a new common key based on the key generation information;
A transmission side registration unit for registering new key identification information and the generated new common key in the transmission side database;
A data encryption unit that encrypts transmission data using a common key extracted from the transmission-side database at the time of transmission of transmission data;
An identification information adding unit for adding key identification information extracted from the transmission side database corresponding to the common key to encrypted transmission data;
The receiving terminal device
A receiver database in which a common key and key identification information for identifying the common key are registered;
A receiver for receiving new key identification information or encrypted transmission data;
A receiving side common key generation unit that generates a new common key based on the key generation information;
A receiving side registration unit for registering new key identification information and the generated new common key in the receiving side database;
Data decryption that searches the receiver database using the key identification information added to the encrypted transmission data, extracts the corresponding common key, and decrypts the encrypted transmission data using the extracted common key And a common key synchronization system. The common key synchronization system according to claim 6,
The data encryption unit encrypts transmission data in units of packets,
The identification information adding unit includes key identification information in a header added to an encrypted packet. The common key synchronization system according to claim 7,
Key identification information is a sequence number included in the header and uniquely assigned to each packet,
A key synchronization information group indicating a plurality of sequence numbers sequentially assigned to each packet is registered in the transmission database and the reception database as key identification information. In the common key synchronization system according to claim 6 or 7,
The receiver database stores the newest common key among the registered common keys as a working common key,
The receiving side registration unit uses a new common key generated corresponding to the new key identification information sent from the transmitting side terminal device as a new common key whose use is temporarily prohibited, Register with the receiver database with the information,
The data decryption unit searches the receiver database using the key identification information added to the encrypted transmission data when receiving the encrypted transmission data from the transmitter terminal device, When the identification information corresponds to the next common key, the common key synchronization system includes a common key changing unit that changes the current common key to the old common key and changes the next common key to the current common key. . The common key synchronization system according to claim 6,
The sender database and the receiver database store a common key and key identification information for each destination address,
A common key synchronization system wherein generation and registration of a common key and key identification information are performed for each destination address.

Images