WO2008029853A1

WO2008029853A1 - Encryption key delivery device and encryption key delivery method

Info

Publication number: WO2008029853A1
Application number: PCT/JP2007/067331
Authority: WO
Inventors: Kunihiko Sakaibara
Original assignee: Panasonic Corporation
Priority date: 2006-09-05
Filing date: 2007-09-05
Publication date: 2008-03-13
Also published as: JP2008066882A

Abstract

It is possible to provide an encryption key delivery device and an encryption key delivery method capable of maintaining security intensity and performing reliable and flexible communication. A generation unit formed by a fist phase key mixer (210) and second phase key mixers (221-223) generates a packet encryption key for each of packets to be transmitted to a plurality of radio reception terminals by multicast or broadcast so as to encrypt the packet. A packet encryption key holding unit (220) holds a plurality of packet encryption keys generated by the generation unit for a plurality of continuous packets. A packet encryption key delivery unit (260) delivers any one of the packet encryption keys held by the packet encryption key holding unit (220) to one of the radio reception terminals independently of the packet transmitted by multicast or broadcast.

Description

Specification

Encryption key distribution apparatus and encryption key distribution method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a secret key distribution apparatus and encryption key distribution method used in multicast communication or broadcast communication.

Background art

In order to utilize the convenience of a conventional IP (Internet Protocol) network, wireless work represented by wireless LAN (Wireless Local Area Network) is progressing. In addition, wireless communications are becoming faster and more IP-oriented in a wide range of outdoor communications. In particular, in the IP network using wireless, various methods focusing on high-speed mobility and convenience are being studied, and the realization of the ubiquitous network is progressing along with the increase in communication speed. Furthermore, in the future, it is expected that hundreds or thousands of users will share the same data, and more and more broadcast and multicast communications will increase (see Non-Patent Document 1).

[0003] In wireless communication, there is a risk that the contents of data may be intercepted and stolen by a third party, and the possibility increases as the communication area is outdoors and widespread, or as communication equipment becomes more common. Become. For this reason, wireless LANs use a fixed encryption key called WEP (Wired Equivalent Privacy) to encrypt data in wireless communications. However, the speed-up of the current signal processing equipment makes it easier to analyze this cipher. The cipher is changed from the initial 40-bit unit code to the 128-bit unit code and further to the 256-bit unit code. The complexity of computerization is progressing. In other words, in order to pursue the confidentiality of data, encryption keys that are inevitably long and infinitely long have been required.

[0004] In order to cope with such WEP vulnerabilities, strong encryption schemes such as TKIP (Temporal Key Integrity Protocol) have been proposed and put into practical use. In this method, the encryption key called the temporary key is periodically updated, and the shorter the update cycle, the stronger the security. About multicast communication system using TKIP encryption This will be described with reference to FIGS.

FIG. 3 is a diagram illustrating an example of a configuration of a conventional communication system. FIG. 4 is a diagram showing an encryption block and a communication form of the communication system of FIG.

In FIG. 3, conventional communication is basically performed assuming one-to-one communication. In order to realize multi-communication, it was necessary to use multiple lines. This one-to-one communication is performed by the server 10 or the encryption device 20 having a function equivalent to the server 10 and the wireless receiving terminals 30 that exist in these communication areas and are connected to the network at the start of communication. Between 31 and 32. Communication data in this communication includes the terminal MAC (Media Access Control) address, TA (Transmitter Address) and other unique information of the communication terminal, the temporary key TK (Temporal Key), and the hash function (Hash Function). The communication is encapsulated using the encryption key generated from the initialization vector IV (Initialization Vector) that indicates the initial value when it is treated as a long code sequence.

More specifically, as shown in FIG. 4, phase 1 key mixer 70 generates a first key number from temporary key TK, terminal Μ AC address, TA, and initialization vector IV. Next, the phase 2 key mixer 71 generates a second encryption key for each packet from the first encryption key generated by the phase 1 key mixer 70 and the initialization vector IV. Then, using the second encryption key generated by the phase 2 key mixer 71, the encryption encapsulation unit 72 encrypts and encapsulates the packet that is the communication data, and the wireless receiving terminals 30 to 32 Communicate with each other individually. Here, since the initialization vector IV is incremented for each packet and changes every moment, it is possible to dynamically change the second encryption key used for communication with each wireless receiving terminal. Note that IPSec (IP Security) has the same concept and uses more advanced encryption.

Non-Patent Document 1: Wireless Ubiquitous (Hidewa System)

Disclosure of the invention

Problems to be solved by the invention

However, in the conventional communication technology, since the terminal MAC address and TA of the radio receiving terminal are used as elements for generating the encryption key, encryption is individually performed for each radio receiving terminal. There is a problem that it is necessary to generate a stream. Also, fixed IP IPSec, which realizes encrypted tunneling between them, is a security that assumes individual communication with each wireless receiving terminal, and has the same problems. That is, the conventional encryption technology is not suitable for group communication or multicast communication in which the same data is transmitted by designating a plurality of parties.

[0009] In addition, when communication is performed using the same encryption key for a plurality of communication terminals, the encryption key can be appropriately updated as described above. Therefore, the network can be used after communication is started without obtaining an initial encryption key. There is a problem that the wireless receiving terminals (for example, the wireless receiving terminal 40 and the wireless receiving terminal 50 in FIG. 3) connected to the network are difficult to follow-up to the multicast communication encrypted for the group. Similarly, a wireless reception terminal (for example, wireless reception terminal 60 in FIG. 3) that has been temporarily disconnected due to a failure during communication and has not been able to acquire an intermediate encryption key and has reconnected to the network (for example, wireless reception terminal 60 in FIG. 3) However, there is a problem that it is difficult to return to the encrypted multi-cast communication. The problem of subsequent follow-up / participation and return to multicast communication becomes more difficult as the security of multicast communication increases.

[0010] As described above, in the conventional multicast communication technology, unlike the always-connected wired network, it is not considered to deal with various fluctuation factors that occur when wireless communication is used. Of course, as described above, it is possible to encrypt the communication contents independently for each terminal, but the encryption process and the decryption process facilitate communication delays and support at least high-speed wireless communication protocols. There is a high possibility that it will not.

[0011] The present invention has been made in view of strength and strength, and provides an encryption key distribution device and an encryption key distribution method capable of performing reliable and flexible communication while maintaining security strength. The purpose is to provide.

Means for solving the problem

[0012] The encryption key distribution device of the present invention includes a generation unit capable of generating an encryption key for encrypting a packet transmitted to a plurality of radio reception terminals by multicast or broadcast for each minimum packet, A holding unit that holds a plurality of encryption keys generated by the generation unit for a plurality of consecutive packets, and any of the holding units held by the holding unit with respect to! / Some encryption keys are multicast or It adopts a configuration comprising a distribution unit that distributes independently of packets transmitted by loadcast.

[0013] The encryption key distribution method of the present invention includes a generation step capable of generating an encryption key for encrypting a packet transmitted to a plurality of radio receiving terminals by multicast or broadcast for each minimum packet, A holding step for holding a plurality of encryption keys generated for a plurality of consecutive packets, and any one of the plurality of key codes for! /, Misalignment of the plurality of wireless receiving terminals And a distribution step of distributing the key number independently of a packet transmitted by multicast or broadcast.

The invention's effect

[0014] According to the present invention, a plurality of packet encryption keys for consecutive packets are generated in advance, held, and distributed to a plurality of receiving terminals, so that reliable and flexible communication is maintained while maintaining security strength. It can be performed.

Brief Description of Drawings

FIG. 1 is a diagram showing an example of the configuration of a multicast communication system according to an embodiment of the present invention.

FIG. 2 is a diagram showing encryption blocks and communication forms of the multicast communication system of FIG.

FIG. 3 is a diagram showing an example of the configuration of a conventional communication system

FIG. 4 is a diagram showing an encryption block and a communication form of the communication system of FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an example of a configuration of a multicast communication system according to an embodiment of the present invention.

In FIG. 1, a multicast communication system 100 includes a server 110, a wireless transmission terminal (hereinafter simply referred to as “transmission terminal” !!), six wireless reception terminals (hereinafter simply referred to as “reception terminal” and! 130, 140, 150, 160, 170, 180. For convenience, the main source of data is the sending terminal and the receiving destination is the receiving terminal.

[0019] Receiving terminals 130 to 180 are the same multicast group in multicast communication. Registered in the group. Therefore, the receiving terminals 130 to 180 have a common multicast address set or hold a common group key! /.

[0020] The sending terminal 120 and the receiving terminals 130 to 180 are VPN (Virtual Private Network) devices that encrypt the entire packet using a packet encryption key and add a new header to the packet and encapsulate it for transmission. Function.

The server 110 stores and manages various data such as video and audio. The server 110 provides data managed by the server 110 to the transmission terminal 120 and other terminals, which are client computers, through a network such as the Internet. The data stored and managed by the server 110 includes, for example, a key such as a temporary key TK used between each multicast group and an ID such as a user ID and a group ID set for each multicast group. included.

[0022] The transmission terminal 120 as the 喑 key distribution device is, for example, an access point (AP) or a base station (BS). The transmitting terminal 120 encrypts a packet of data such as video and audio using a packet encryption key, and multicasts it to the receiving terminals 130-180. The sending terminal 120 can send packets to the multicast group consisting of the receiving terminals 130 to 180 simultaneously by setting the multicast address set to the receiving terminals 130 to 180 as the packet destination. . The data constituting the packet transmitted from the transmission terminal 120 is, for example, information provided from the server 110 or information held by itself!

The transmitting terminal 120 generates a packet encryption key for encrypting a packet to be transmitted to the receiving terminals 130 to 180 for each packet. In addition, the transmission terminal 120 holds the packet encryption key generated for a plurality of consecutive packets as a continuous encryption key applied to the plurality of consecutive packets. That is, the transmission terminal 120 holds a packet encryption key for an arbitrary packet and a packet number key for a packet that is continuous with the arbitrary packet.

[0024] More specifically, the transmitting terminal 120 transmits a packet encryption key corresponding to a previously transmitted packet, a packet encryption key corresponding to a previously transmitted packet, and a packet corresponding to a subsequently transmitted packet together with the packet encryption key corresponding to the currently transmitted packet. Holds the encryption key. That is, the transmitting terminal 120 In addition to the packet encryption key to be used, a plurality of packet encryption keys used before or after the update are generated in advance (advanced generation). Note that the number of packet number keys generated in advance can be arbitrarily determined according to the capability of the transmission terminal 120 or an agreement between the transmission terminal 120 and the reception terminals 130 to 180.

[0025] The transmitting terminal 120 is generated in advance when receiving a request to distribute a packet code key (hereinafter referred to as a "packet encryption key distribution request") from a receiving terminal that is a member of a multicast group. Distribute the packet encryption key to the receiving terminal. At this time, the transmitting terminal 120 delivers together the packet encryption key requested by the packet encryption key distribution request and the packet encryption key continuous with the packet encryption key. For example, when the transmitting terminal 120 distributes a packet encryption key corresponding to a currently transmitted packet, the transmitting terminal 120 transmits a packet encryption key corresponding to a previously transmitted packet and a packet number corresponding to a subsequently transmitted packet. The ability to distribute keys in a batch is possible. As a result, the receiving terminal to which the packet encryption key is distributed can smoothly follow-up / enter / return to / from multicast communication. In addition, storing and holding the distribution data allows the previously transmitted packet to be decoded, so that more accurate data can be reproduced.

[0026] Generation, retention and distribution of the packet encryption key by the transmission terminal 120 and transmission of the packet using the packet encryption key will be described in detail later with reference to FIG.

[0027] The receiving terminals 130 to 180 are, for example, a personal computer having a wireless LAN interface or its peripheral devices. The receiving terminals 130 to 180 receive the packets transmitted from the transmitting terminal 120. The receiving terminals 130 to 180 use the packet encryption key delivered from the transmitting terminal 120 to decrypt the received packet. The receiving terminals 130 to 180 reproduce the decrypted packet.

[0028] The receiving terminals 130 to 180 do not hold the packet encryption key corresponding to the packet that is desired to be decrypted, and therefore cannot decrypt the packet and cannot participate in multicast communication. The packet encryption key distribution request is transmitted to the transmission terminal 120. This packet encryption key distribution request is an inquiry about the state of the packet encryption key, that is, the packet encryption key currently used and the packet encryption key used before and after it. Information inquiry. The packet encryption key distribution request is required when, for example, the network is connected after the start of communication without acquiring the initial packet encryption key (follow-up entry), or after the communication is temporarily disconnected. It may be possible to reconnect to (return).

[0029] Next, the function of the transmission terminal 120 will be described in more detail with reference to FIG.

FIG. 2 is a diagram showing an encryption block and a communication form of the multicast communication system 100 of FIG. Here, the encryption block shown in FIG.

In FIG. 2, the encryption block includes a first phase key mixer 210, a packet encryption key holding unit 220, a message integrity check (MIC) unit 230, and a fragment unit 240. , A 喑 number encapsulation unit 250 and a packet 喑 number key distribution unit 260 are provided.

[0032] The packet encryption key holding unit 220 includes a plurality of second phase key mixers, here, three second phase key mixers 221, 222, 223.

[0033] The first phase key mixer 210 as the first generation unit uses the temporary key TK, the multicast address or group key (Group Key), and the initialization vector IV to generate the packet number key. An element key (hereinafter referred to as “reserve key”) is generated. The first phase key mixer 210 generates this spare key once in N packets (N is an arbitrary integer). That is, the first phase key mixer 210 updates the spare key by generating a new spare key every N packets. The first phase key mixer 210 outputs the generated spare key to each of the second phase key mixers 22;! To 223 of the packet encryption key holding unit 220.

[0034] The temporary key TK is a long (for example, 128 bits) key that is shared between the transmitting terminal 120 and the receiving terminals 130 to 180 and generated by a hash function or the like. Each receiving terminal can obtain the temporary key TK by various methods, for example, key distribution by ΙΕΕΕ802.1χ. The initialization vector IV indicates an initial value extracted from the temporary key TK according to a certain rule, and is automatically generated by the transmission terminal 120. This initialization vector IV is 48 bits, for example, and is incremented every packet and changes every moment.

[0035] The second phase key mixer 22;! To 223 as the second generation unit respectively includes a spare key input from the first phase key mixer 210 and the initialization vector IV. Packet encryption key Is generated. The second phase key mixer 22;! To 223 generates a packet encryption key for each one of consecutive packets transmitted to each receiving terminal. Here, the packet encryption key generated by the second phase key mixer 221 is Key (n—1), and the packet encryption key generated by the second phase key mixer 222 is Key (n). The packet encryption keys generated by the second phase key mixer 223 are represented by Key (n + 1), respectively. That is, Key (n) is a packet encryption key corresponding to the currently transmitted packet, Key (n-l) is a packet signature key corresponding to the packet transmitted before Key (n), and Key (n n + 1) is a packet encryption key corresponding to a packet transmitted after Key (n). Key (n-l), Key (n), and Key (n + 1) function as a continuous sign key generated for a plurality of consecutive packets, for example, three consecutive packets. Each of Key (n−1), Key (n), and Key (n + 1) is the above-described WEP key.

[0036] As described above, the generation unit configured by the first phase key mixer 210 and the second phase key mixer 22;! To 223 is transmitted to a plurality of radio receiving terminals by multicast. It functions as a generator that generates a packet encryption key for each packet.

Since the initialization vector IV changes from moment to moment for each packet, Key (n−1), Key (n), and Key (n + 1) are different packet encryption keys. Further, as described above, the spare key input from the first phase key mixer 210 is updated every N packets, and the packet encryption key is periodically refreshed along with this update. In this way, the first phase key mixer 210 and the second phase key mixer 22;! To 223 are generated by combining both the change of the initialization vector IV and the update of the reserve key. Packet encryption key encryption process can be strengthened. In other words, it is possible to improve the security of encrypted communication by increasing the irregularity of the packet encryption key used for each packet.

[0038] The packet number key holding unit 220 serving as a holding unit receives the packet encryption key generated by the second phase key mixer 22;! To 223 of the continuous packet transmitted to each receiving terminal. It is stored as a continuous encryption key corresponding to each. That is, the packet encryption key holding unit 220 converts the packet encryption key generated by the second phase key mixer 22;! It is stored as a common continuous encryption key that is used while updating every packet with the Yust Group. As a result, the packet encryption key holding unit 220 supports the packet encryption key corresponding to the currently transmitted packet, the packet key corresponding to the previously transmitted packet, and the packet transmitted thereafter. Packet encryption key to be stored.

[0039] Here, since the packet number key has a multicast address common to the multicast group, not the terminal MAC address and information unique to the receiving terminal such as TA, the menno of the same multicast group, In this case, the receiving terminals 130 to 180 can use the same packet encryption key.

[0040] MIC section 230 checks the integrity of the communication data by detecting tampering of the communication data carried in the packet. More specifically, the MIC unit 230 is a packet source address SA (Source Address), a packet destination address DA (Destination Address), and unencrypted raw data using the MIC key. Priority plaintext MSDU (MA C Service Data Unit) Data integrity check. The MIC unit 230 outputs the MSDU data after the inspection to the fragment unit 240.

The fragment unit 240 converts the MSDU data input from the MIC unit 230 into MPDU (MAC Protocol Data Unit) data that is a MAC frame. The fragment unit 240 outputs the converted MPDU data to the No. 2 encapsulation unit 250.

[0042] The 喑 number encapsulation unit 250 encrypts and encapsulates the MPDU data input from the fragment unit 240 using the packet number key held by the packet number key holding unit 220. That is, the 喑 encapsulation unit 250 encrypts the MPDU data itself with the packet 鍵 key and generates a packet with a new header added thereto. The cryptographic encapsulation unit 250 multicasts the generated packet to the receiving terminals 130 to 180 that are members of the multicast group.

[0043] As described above, since the packet encryption key is held in the packet encryption key holding unit 220 for each packet of the continuous packets to be transmitted, the 喑 encapsulating unit 250 is used for each packet. Packets can be continuously encrypted using different packet encryption keys. For example, the encryption encapsulating unit 250 encrypts these three packets when encrypting three consecutive packets. The packet is continuously encrypted in the order of Key (n-l), Key (n), and Key (n + 1). For example, assuming that Key (n) is the packet encryption key for encrypting the currently transmitted packet, Key (n—1) encrypts the packet transmitted before Key (n). Key (n + 1) is a packet encryption key for encrypting packets transmitted after Key (n).

[0044] The 喑 encapsulation unit 250 encrypts the MPDU data using RC4, which is an encryption algorithm used in the 喑 method with the same 喑 key and decryption key. Therefore, in order for the receiving terminals 130 to 180 that are members of the multicast group to participate in multicast communication, it is necessary to share the packet encryption key held in the packet encryption key holding unit 220.

[0045] The packet encryption key distribution unit 260 as the distribution unit is held in the packet encryption key holding unit 220! /, And any one of the packet numbers is received by the receiving terminals 130-180 that are members of the multicast group. Deliver to either. Thereby, the packet encryption key is shared between the transmitting terminal 120 and the receiving terminals 130 to 180. The packet encryption key distribution unit 260 distributes the packet encryption key independently of the packet transmitted by multicast.

More specifically, upon receiving a packet encryption key distribution request from any of the receiving terminals 130 to 180 that are members of the multicast group, the packet number key distributing unit 260 sends the request to the receiving terminal. , Deliver the packet encryption key. At this time, the packet encryption key distribution unit 260 distributes the packet encryption key requested by the packet encryption key distribution request together with the packet encryption key and the packet encryption key continuous. For example, if the packet encryption key requested by the packet encryption key distribution request is Key (n), the packet encryption key distribution unit 260, together with Key (n), Key (n-l), Key (n + 1) Is distributed to the receiving terminal that is the transmission source of the packet number key distribution request.

Here, the packet encryption key distribution unit 260 can also provide means for detecting a receiving terminal that failed to acquire the packet encryption key in the packet encryption key distribution unit 260. In this case, the bucket number key distribution unit 260 is unable to acquire the packet encryption key for the receiving terminal that has failed to acquire the packet encryption key, the packet encryption key, and the continuous packet encryption key. Deliver [0048] Thus, since the packet encryption key is individually distributed to the receiving terminal that requests acquisition of the packet encryption key, that is, the receiving terminal that enters or returns to multicast communication or broadcast communication, each receiving terminal It is possible to smoothly follow up on communication and return to multicast communication that was disconnected on the way. In addition, since not only the required packet encryption key but also the packet encryption keys used before and after the update are delivered together, each receiving terminal has a reliable connection to the once-connected multicast communication. Can be maintained.

[0049] Note that the number of packet encryption keys distributed collectively by the packet encryption key distribution unit 260 can be arbitrarily set. For example, when there are five or more second phase key mixers, the packet number key distribution unit 260 can collectively distribute packet encryption keys corresponding to five consecutive packets. Maintaining communication can be ensured by increasing the margin of packet encryption key distribution.

The operation of multicast communication system 100 configured as described above will be described below. Here, the packet encryption key distribution operation by the packet encryption key distribution unit 260, particularly the packet encryption key distribution operation after receiving the packet encryption key distribution request of the receiving terminal will be described.

[0051] When receiving a packet encryption key distribution request from one of the receiving terminals that are members of the multicast group, the packet number key distributing unit 260 distributes the packet number key to the receiving terminal. At this time, the packet encryption key distribution unit 260 distributes the packet encryption key requested by the packet encryption key distribution request together with the packet encryption key continuous with the packet encryption key. For example, when the packet encryption key distribution unit 260 has the packet encryption key strength _e y (n) requested by the packet encryption key distribution request, the key encryption key _e y (n), Ke y (n− l), Key (n + 1) is delivered to the receiving terminal that sent the packet encryption key delivery request.

[0052] Thus, the receiving terminal can smoothly follow up on multicast communication and return to multicast communication disconnected on the way. For example, in FIG. 1, a receiving terminal 160 connected to the network after a multicast communication session is established, a receiving terminal 170 that has moved from outside the multicast communication area, and a multicast terminal. Receiving terminal 180 that has been disconnected because it is located at the boundary of the communication area of multicast communication, receives exceptional packet signature key distribution by sending a packet encryption key distribution request. Can do. Then, the receiving terminals 160, 170, and 180 can follow-up V, enter or return to multicast communication using the packet encryption key distributed from the packet signal key distribution unit 260.

[0053] Further, the receiving terminal can maintain the connection to the multicast communication once connected with high reliability. For example, a receiving terminal that has transmitted a packet encryption key distribution request for Key (n), together with Key (n), Key (n—1), Key (n + 1) used before and after updating Key (n) ) Can be obtained. As a result, even if the packet encryption key is updated shortly after sending the packet encryption key distribution request, the receiving terminal uses the Key (n + 1) distributed with the Key (n), Connection to multicast communication can be maintained. In addition, since the receiving terminal can decrypt the previously transmitted packet by using Key (n-1), it is possible to reproduce data with higher accuracy.

As described above, according to the present embodiment, transmitting terminal 120 generates and holds a plurality of packet encryption keys for consecutive packets transmitted to a plurality of receiving terminals in advance. These packet encryption keys are distributed to multiple receiving terminals. That is, a server for generating the encryption key or an equivalent replacement means is prepared, and the current key is notified by a separate means in response to the request. As a result, even if each receiving terminal cannot acquire a packet encryption key on the way for some reason, it can smoothly follow up on multicast communication and return to multicast communication that was cut off on the way. Can do.

[0055] Also, according to the present embodiment, transmitting terminal 120 distributes a plurality of packet encryption keys for consecutive packets in a lump. As a result, each receiving terminal can maintain the participation in the multicast communication once connected with high reliability. In addition, each receiving terminal can decode a previously transmitted packet, and can reproduce data with higher accuracy.

In the present embodiment, the first phase key mixer 210 has been described as calculating and updating a new spare key every N packets, but the present invention is not limited to this. For example, the first The phase key mixer 210 may calculate and update a new spare key every M packets (M is an arbitrary integer different from N) determined for each system. In doing so, the first phase key mixer 210 can calculate and update a new reserve key according to a certain cycle based on a random number. Furthermore, the backup key may be updated by irregular and ruled means. Encrypted communication with higher security strength can be realized by refreshing the packet encryption key by using such update of the spare key.

Further, in the present embodiment, the force S in which the packet encryption key distribution mechanism (encryption key distribution device) is provided inside the transmission terminal 120 is not limited to this. For example, the encryption key distribution device may be provided in the multicast communication system as a device unit separate from the transmission terminal 120.

Further, although an example in which the present embodiment is applied to multicast communication has been described in the present embodiment, the same effect as that in the case of multicast communication can be realized even when applied to broadcast communication. Further, it may be applied to unicast communication. Moreover, the effect may be improved by combining them.

[0059] This specification is based on Japanese Patent Application No. 2006-240691 filed on Sep. 5, 2006. All this content is included here.

Industrial applicability

[0060] The encryption key distribution device and the encryption key distribution method according to the present invention have an effect of performing reliable and flexible communication while maintaining security strength, and in multicast communication or broadcast communication. It is useful as the encryption key distribution device and encryption key distribution method used.

Claims

The scope of the claims

[1] A generation unit capable of generating an encryption key for encrypting at least one packet for encrypting a packet transmitted to a plurality of wireless receiving terminals by multicast or broadcast, and the generation for a plurality of consecutive packets. A holding unit for holding a plurality of encryption keys generated by the unit;

Deliver the! / Either key that is held by the holding unit, independently of the packets transmitted by multicast or broadcast, for any of the! /, Shifts of the plurality of wireless receiving terminals A distribution department;

An encryption key distribution apparatus comprising:

[2] The distribution unit

V, distributes the encryption key generated for the misaligned packet and the! /, The encryption key generated for the other consecutive packets of the misaligned packet,

The encryption key distribution device according to claim 1.

[3] The distribution unit

An encryption key is distributed to a wireless receiving terminal that joins or returns to multicast communication or broadcast communication among the plurality of wireless receiving terminals.

The encryption key distribution device according to claim 2.

[4] The distribution unit

The encryption key distribution device according to claim 2, wherein the encryption key is distributed to a wireless receiving terminal that is a transmission source of a request for distributing the encryption key.

[5] The generation unit includes:

A first generation unit that generates a backup key from a plurality of elements including a temporary key and an initialization vector; and a second generation unit that generates an encryption key from the backup key and the initialization vector.

The first generator refreshes the encryption key generated by the generator by periodically updating the temporary key; The encryption key distribution device according to claim 1.

[6] The first generation unit updates the temporary key according to a cycle according to a certain rule based on a random number.

6. The encryption key distribution device according to claim 5.

[7] A generation step capable of generating at least one packet of an encryption key for encrypting a packet transmitted to multiple wireless receiving terminals by multicast or broadcast;

A holding step for holding a plurality of encryption keys generated for a plurality of consecutive packets;

Distribute the key of any one of the plurality of encryption keys independently of the packet transmitted by multicast or broadcast to any of! A delivery step;

An encryption key distribution method comprising: