JP4694240B2 - Encryption key distribution apparatus and program thereof - Google Patents

Description

  The present invention relates to a multicast distribution technique, and more particularly to a technique for providing multicast contents only to authenticated clients.

  FIG. 1 shows a multicast distribution system using the prior art. The multicast distribution system shown in FIG. 1 includes a content distribution server that distributes content, a multicast-compatible router, and a client that receives the multicast-distributed content. In the example of FIG. 1, each client can communicate with the Internet via a wireless access point. The wireless access point is connected to the multicast-compatible routers 1 and 3 via the layer 2 switch.

  Each client has a function related to multicast such as IGMP. In order for clients under the multicast-capable routers 1 and 3 to receive multicast distribution of content corresponding to a specific multicast address, first, one of the clients (for example, the client 5) distributes including the multicast address to the content distribution server. Send a request. The content distribution server that has received the distribution request transmits the content, the content is transmitted to the multicast-compatible router 1, and the multicast-compatible router 1 multicasts the content to all the clients in the network area where the client 5 exists, Only clients participating in the multicast group corresponding to the content receive the content.

As a conventional technique related to multicast, there is a technique disclosed in Patent Document 1, for example. Further, there are Non-Patent Documents 1 to 5 as references related to multicast.
JP 2002-026903 A Internet STD5, RFC1112 `` Internet Group Management Protocol (IGMP) '' IETF Network Working Group, August, 1989 Internet RFC2876 "Multicast Listener Discovery (MLD) for IPv6" IETF Network Working Group, October, 1999 Internet Draft "Explicit Multicast (Xcast) Basic Specification" R. Boivie (IBM) et al., January, 2003 Internet RFC3547 “The Group Domain of Interpretation” M. Baugher (Cisco) et al., July, 2003 Internet RFC3775 “Mobility Support in IPv6” D. Johnson (Rice University) et al., June, 2004

  In the above prior art, the content requested by a certain client can be received by all the participating clients existing in the same area as that client. Therefore, there is a problem that it is impossible to perform control such that only the authenticated client can view the multicast content and the unauthenticated client is prevented from viewing the multicast content.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a technique for preventing another unauthenticated client from viewing a multicast packet being received by an authenticated client.

  An object of the present invention is to provide an encryption key distribution apparatus for multicast distribution of a content encryption key for encrypting and decrypting predetermined multicast content, the holding means for storing an address of an authenticated client, and the multicast To a content distribution device that distributes content, a content distribution device encryption key transmission means for transmitting a key encryption key for encrypting and decrypting the content encryption key, a key request and the multicast content A client encryption key transmission means for receiving the multicast address and transmitting the key encryption key to the client when the address of the key request source is the address of the authenticated client; and the content distribution apparatus From the above When receiving the multicast distribution request for the content encryption key, the content encryption key is encrypted with the key encryption key, the encrypted content encryption key is multicast distributed to an area where the content distribution device exists, and the client It can be solved by an encryption key distribution device comprising multicast distribution means for multicast distribution of the encrypted content encryption key to an area where the client is present when a multicast distribution request for the content encryption key is received.

  The encryption key distribution device further includes means for updating the content encryption key, and when the multicast distribution unit receives a multicast distribution request for the content encryption key, the multicast distribution request transmission source device area Session information that associates the destination information corresponding to the content address with the multicast address for multicast distribution of the content encryption key, and the updated content encryption key is updated when the content encryption key is updated. The key may be multicasted based on the session information.

  The encryption key distribution device holds a list of client attribute values to which a content encryption key can be distributed for each multicast content, and the encryption key distribution device is authenticated by an authentication device that performs client authentication. The client address and the attribute value corresponding to the client are received, the holding unit holds the address and the attribute value in association with each other, and the client encryption key transmission unit is configured to transmit the key request and the multicast The multicast address of the content is received, the source address of the key request is the address of the authenticated client, and the attribute value corresponding to the address is the attribute value corresponding to the multicast content. If the client is included in the list of It may be transmitted to the key encryption key.

  According to the present invention, a key encryption key for encrypting and decrypting a content encryption key corresponding to a predetermined multicast content is transmitted to the content distribution apparatus, and the client is based on a request from the authenticated client. The content encryption key obtained by encrypting the content encryption key with the key encryption key is multicast-distributed to each of the content distribution device and the client. Only authenticated clients with a key encryption key can decrypt and view. Therefore, it is possible to prevent other unauthenticated clients from viewing the multicast packet being received by the authenticated client.

  Embodiments of the present invention will be described below with reference to the drawings.

A multicast distribution system according to an embodiment of the present invention is shown in FIG. As shown in FIG. 2, this multicast distribution system includes a content distribution server (CDS) having a mobile IPv6 node function, an address mapping server (AMS), a multicast control gateway (MCG). Server), splitter (SP), home agent (HA), and multicast encryption key server (KS) are connected to the IP network.
Each multicast control gateway (MCG) is connected to a wireless access point (AP) via a layer 2 switch, and there are clients or content distribution servers (CDS) under the control.

  The content distribution server (CDS) is a server that uses this system to stream content, and each client is a user terminal that uses the stream-distributed content. The client connects to the multicast control gateway (MCG) via the wireless access point (AP) and receives the multicast content from the multicast control gateway (MCG). Hereinafter, the function of each device constituting the multicast distribution system of the present embodiment will be described.

  The address mapping server (AMS), for each content, a multicast address corresponding to the content (which may be referred to as a multicast channel or a multicast group) and attributes of the content (the home address of the content distribution source server, the content) Distribution area, stream bandwidth, encryption method, etc.). For example, the content provider sets the values of these attributes.

  The “area” in the present embodiment is a network area identified by the network part of the IP address, but is not limited to this, and various definitions are possible. By associating network areas with “hotels”, “restaurants”, “schools”, etc., these can also be used as “areas”. “Multicast” in the present embodiment is an IP multicast defined in IETF RFC1112, RFC2710, or the like, but the multicast to which the present invention is applied is not limited to this.

  The multicast control gateway (MCG) receives the content distribution request from the client, acquires the content attribute from the address mapping server (AMS), and distributes the requested content to the area where the content requesting client exists. If possible, it requests the splitter (SP) and content distribution server (CDS) to create a content distribution tree and distribute the content. Thereafter, the unicast-encapsulated content distributed along the content distribution tree is restored to multicast, and is multicast distributed to the area of the content requesting client. Also, the MCG can control whether multicast distribution is possible in VLAN units (VLAN network address units). The multicast control gateway (MCG) also has an authentication gateway function.

  The splitter (SP) forms a distribution tree for efficiently distributing content from the content distribution server (CDS) to each MCG, and the content is transmitted from the content distribution server (CDS) to each multicast control gateway (MCG). Branch delivery by relaying the stream.

  The multicast encryption key server (KS) has a function of creating an encryption key of a packet for each multicast channel and distributing it to the content distribution server and the multicast reception client.

  A home agent (HA) is a device (for example, a router) having a mobile IPv6 home agent function (defined in draft-ietf-mobileip-ipv6), and manages a home address and a care-of address in pairs. . In addition, when the home agent (HA) of this embodiment authenticates the content distribution server (CDS) at the time of binding update or the like, the authentication result is sent to the multicast control gateway (MCG) under the content distribution server (CDS). ).

  In the example shown in FIG. 2, under each multicast control gateway (MCG), a VLAN (virtual LAN) is constructed by using a layer 2 switch, and one area formed by the VLAN is one wireless access point (AP). Is associated with. The location (address and communication port) of the address mapping server (AMS) is preset in the multicast control gateway (MCG), and direct communication is possible between the address mapping server (AMS) and each multicast control gateway (MCG). .

  The multicast control gateway (MCG) is configured to be able to use IP multicast, but in the wide area network upstream from the multicast control gateway (MCG), only unicast distribution is possible. However, content distribution from the content distribution server (CDS) is performed as unicast by encapsulating IP multicast packets into unicast packets. That is, in content stream transfer from the content distribution server (CDS) to each multicast control gateway (MCG), IP multicast packets are encapsulated into unicast packets and distributed. The outline of the operation of the system configured as described above is as follows.

  When a client sends a content distribution request to the multicast control gateway (MCG), the multicast control gateway (MCG) performs address mapping between the area identification information to which the client belongs and the requested content identification information (multicast address). The AMS determines whether or not the content can be received in the area from the received information, and if possible, the information including the home address of the content distribution server (CDS) is transmitted to the multicast control gateway. Returning to (MCG), the MCG transmits a content distribution request to the content distribution server (CDS) at the address via the splitter (SP). The content distribution server (CDS) that has received the distribution request transmits the requested content. The content is transferred to a multicast control gateway (MCG) as a request transmission source along a route through which the distribution request has passed, and is multicast distributed from the MCG to clients in the area related to the request.

  Next, the configuration of each device will be described. FIG. 3 is a functional block diagram of the multicast control gateway (MCG).

  The multicast control gateway (MCG) includes an authentication check unit 17, a packet filter unit 18, a stream distribution unit 11, a stream reception unit 12, a stream distribution request unit 14, a content attribute request unit 13, a content reception client detection unit 16, and a multicast restoration unit. 19, HA communication unit 10, KS communication unit 9, client authentication unit 20, and control unit 15. The control unit 15 includes an authentication state management unit 151, a session management unit 152, and an area information management unit 153.

  The content reception client detection unit 16 receives a content distribution request message for requesting multicast distribution of content from the client. This message is IGMP Report or MLD Report.

  The stream delivery unit 11 multicasts the requested content to the client. The stream distribution request unit 14 transmits a content distribution request message to the content distribution server (CDS) or the splitter (SP). The stream receiving unit 12 receives content stream-distributed from a content distribution server (CDS) or a splitter (SP). The content attribute request unit 13 transmits a message requesting content attributes to the address mapping server (AMS) and receives a response.

  The HA communication unit 10 has a function of transmitting and receiving binding information between a home agent (HA) and a mobile IP client (content distribution server (CDS) in the present embodiment). The KS communication unit 9 notifies the authentication status of the client to the multicast encryption key server (KS).

  The authentication check unit 17 has a function of checking whether or not the packet is information transmitted from an authenticated client from the header information of the received IP packet. Further, when receiving an IP packet from the client, the packet filter unit 18 forwards the packet to its destination if it is transmitted from the authenticated client. Otherwise, it is discarded except for exceptions (binding information notification to the HA, etc.). The client authentication unit 20 has a function for authenticating the client.

  The multicast restoring unit 19 has a function of restoring the unicast stream received from the CDS or SP to multicast in order to multicast the content to the client group.

  The authentication state management unit 151 of the control unit 15 holds and manages the IP address (global address) and MAC address of the authenticated client in the storage device. The session management unit 152 of the control unit 15 manages a session with a client and a stream transmission / reception session with a content distribution server (CDS) or a splitter (SP). The area information management unit 153 of the control unit 15 has a function of managing area information for each VLAN under the gateway.

  FIG. 4 shows a functional block diagram of the splitter (SP). As shown in the figure, the splitter (SP) includes a content request receiving unit 21, a stream distribution unit 22, a stream distribution request unit 23, a stream reception unit 24, and a control unit 25. Further, the control unit 25 has a session management unit 251.

  The content request reception unit 21 receives a content distribution request message from the downstream multicast control gateway (MCG) or splitter (SP), and the stream distribution unit 22 sends the content to the downstream multicast control gateway (MCG) or splitter (SP). On the other hand, it has a function of streaming the requested content. The stream distribution request unit 23 transmits a content distribution request message to the upstream splitter (SP) or content distribution server (CDS), and the stream reception unit 24 transmits the upstream splitter (SP) or content distribution server. (CDS) has a function of receiving content stream-distributed.

  The session management unit 251 of the control unit 25 manages a stream transmission / reception session with the downstream splitter (SP), the multicast control gateway (MCG), and the upstream splitter (SP) or content distribution server (CDS).

  FIG. 5 shows a functional block diagram of the address mapping server (AMS). As shown in the figure, the address mapping server (AMS) includes a content attribute request receiving unit 31, a content attribute transmitting unit 32, a content attribute management database 33, an attribute operation user interface unit 34, and a control unit 35. The control unit 35 includes a database access unit 351 and a content distribution availability control unit 352.

  The content attribute request receiving unit 31 receives a content attribute request message from the multicast control gateway (MCG). The content attribute transmission unit 32 transmits a response message to the content attribute request to the content attribute request source MCG. Information including the content attribute is transmitted as a response message to the MCG in the distributable area. The content attribute management database 33 manages attribute information in which a multicast address, a distribution source server address, distributable area information, and the like are associated with each content. The attribute operation user interface unit 34 displays a screen for operating content attributes, and receives an attribute operation input from the user.

  The database access unit 351 of the control unit 35 accesses the database 33 and reads / writes attribute values when a content attribute request is received from the multicast control gateway (MCG) and when an attribute operation is performed by the user. The content distribution availability control unit 352 collates the information in the database 33 with the area information of the content attribute request source, and determines whether to permit distribution of the requested content to the area based on the collation result.

FIG. 6 shows a functional block diagram of the multicast encryption key server (KS). As shown in the figure, the multicast encryption key server (KS) includes an authentication information acquisition unit 41, a control unit 42, an encryption key request reception unit 43, an authentication check unit 44, an encryption key creation unit 45, and a multicast encryption key distribution unit 46. The unicast capsule unit 47 and the control unit 42 include an authentication information management unit 421 and a key management unit 422.

  The authentication information acquisition unit 41 obtains the IP address of the client authenticated by the multicast control gateway (MCG) or the home agent (HA) from the multicast control gateway (MCG) or the home agent (HA) (the home address of the MobileIP client). Receive. It also receives the IP address information of the logged out client.

  The encryption key request receiving unit 43 receives a multicast encryption key distribution request from the multicast viewing client. Also, the authentication check unit 44 checks whether the client is an authenticated client from the header information of the packet from the client requesting the encryption key.

  The encryption key creation unit 45 creates a multicast encryption key (TEK: Traffic Encryption Key) and a KEK (Key Encryption Key). In addition, a new TEK is recreated at regular intervals. The multicast encryption key distribution unit 46 distributes the TEK only to clients that have been authenticated by the multicast control gateway (MCG) or the home agent (HA). The unicast capsule unit 47 encapsulates the multicast packet into a unicast packet.

  The authentication information management unit 421 of the control unit 42 manages the IP address of the authenticated client acquired from the multicast control gateway (MCG), the home agent (HA), or the like. Further, the key management unit 422 manages, for each multicast channel, a corresponding multicast encryption key, KEK, and a list of clients that have distributed these keys.

  The functional units in each of the above devices and each means of the present invention are realized by causing a computer to execute a program describing the processing contents described in the present embodiment. Each of the above devices can be realized by a computer having a communication processing function. The multicast control gateway (MCG) and the splitter (SP) can also be realized by a router.

  Next, the basic operation of the system of the present embodiment will be described with reference to the sequence diagram of FIG. This sequence authenticates a content distribution server (CDS), which is a mobile IP client, automatically generates a content multicast distribution tree for a client group requesting a multicast stream, and performs unicast encapsulation from the content distribution server (CDS). 2 is an example of a sequence from receiving a received multicast stream to starting multicast distribution of content.

  The processing sequence in the multicast distribution system according to the present embodiment includes (1) Multicast content registration to AMS, (2) Content distribution server authentication, (3) Content reception request processing, (4) Content distribution tree creation stage, And (5) Content relaying and multicast distribution can be roughly divided into five stages.

(1) Multicast content registration to AMS Register the content attribute information such as the multicast address and the unicast address of the content distribution server (CDS) (here, the mobile IPv6 home address) in advance in the address mapping server (AMS). Keep it.

(2) Content Distribution Server Authentication The content distribution server (CDS) that transmits the multicast content requests authentication from the home agent (HA) (for example, during a binding update) (step 11). It is assumed that information for authenticating the content distribution server (CDS) is registered in advance in the home agent (HA). If this authentication is successful, the home agent (HA) holds the correspondence between the home address of the content distribution server (CDS) and the care-of address, and sends the home address to the multicast control gateway (referred to as MCG1) corresponding to the care-of address. The care-of address and the authentication result are notified (step 12). Based on this notification, the multicast control gateway (MCG1) registers the home address and care-of address of the content distribution server (CDS) as the address of the authenticated content distribution server (CDS).

When a unicast packet transmitted from the content distribution server (CDS) or a unicast packet transmitted to the content distribution server (CDS) is received, the authenticated content distribution is performed based on the registered contents. It is determined that the packet originates from the server (CDS) or is addressed to the authenticated content distribution server (CDS), and is transferred.
(3) Content Reception Request Processing The viewer-side multicast control gateway (referred to as MCG2) is a gateway for a radio access area and manages area information related to a subordinate LAN (VLAN). Here, the client requesting the content is authenticated first, and this process will be described in detail later.

  Further, when a client that has completed the authentication process sends a request for distribution of a certain multicast content (step 13), it is checked whether the distribution request is sent from an authenticated client. Detailed description.

  When a multicast distribution request is issued in step 13, the content reception client detection unit 16 of the multicast control gateway (MCG2) receives the distribution request. This distribution request includes the content identification information (multicast address) and area information.

  Next, the multicast control gateway (MCG2) requests the content mapping server (AMS) from the content attribute request unit 13 in order to request the attribute of the multicast content requested to be distributed to the content distribution server (CDS). A content attribute request message related to the content related to is sent (step 14). In the multicast control gateway (MCG2), it is assumed that the address and port number of the address mapping server (AMS) are preset in the configuration file or the like. The content attribute request message includes area information (including a network prefix, a VLAN ID under MCG2, etc.) of a delivery destination (location where the client exists).

  When the content attribute request receiving unit 31 of the address mapping server (AMS) receives the content attribute request message, the content attribute request receiving unit 31 notifies the control unit 35 of the content of the message. The control unit 35 of the address mapping server (AMS) refers to the content attribute database 33 of the address mapping server (AMS), and collates the distributable area information for the requested content with the distribution destination area information included in the message. To do. If the content distribution is possible to the area where the client exists as a result of the collation, the address mapping server (AMS) notifies the content attribute from the content attribute transmission unit 32 to the MCG 2 (step 15). . The content attribute includes the home address of the content distribution server (CDS).

When the content attribute request unit 13 of the multicast control gateway (MCG2) receives the content attribute, the content attribute request unit 13 notifies the control unit 15 and the control unit 15 manages a pair of a distribution destination area and a multicast address as session information. Then, a content distribution request message is transmitted from the stream distribution request unit 14 of the multicast control gateway (MCG2) to the home address of the content distribution server (CDS) (step 16). This content distribution request message includes the home address, the multicast address corresponding to the requested content, and the address of the request source MCG2.
(4) Content distribution tree creation A packet transmitted to the home address from the multicast control gateway (MCG2) is transmitted to the home agent (HA), and the content distribution server (CDS) having the home address from the home agent (HA). ) Will be forwarded to the care-of address.

  In the present embodiment, some SPs are in the middle of the communication path between the multicast control gateway (MCG2) and the home agent (HA), or in the middle of the communication path between the home agent (HA) and the content distribution server (CDS). A node exists. In the example of FIG. 6, it is assumed that there is a node called SP1 which is one splitter (SP), and SP1 is in the middle of the communication path between the multicast control gateway (MCG2) and the home agent (HA). At this time, the content distribution request message transmitted from the multicast control gateway (MCG2) to the home address of the content distribution server (CDS) is first received by the content request receiving unit 21 of the splitter (SP1). When receiving the content distribution request message, the content request receiving unit 21 of the splitter (SP1) notifies the session management unit 251 of the message. The session management unit 251 of the splitter (SP1) processes this request message as follows.

  (4.1) A pair of a source MCG2 address and a requested content channel (identification information (multicast address)) is managed as session information in the storage device (step 17).

  (4.2) The request source address of the content distribution request message is changed to the address of itself (SP1) instead of the original MCG2. Then, the rewritten content delivery request message is sent to the home address (step 18).

  The content distribution request message is then distributed to the home agent (HA), and the request message is transferred from the home agent (HA) to the content distribution server (CDS) (step 19). This request message passes through MCG1, but MCG1 determines that the content distribution server (CDS) has been authenticated, and permits transfer. When receiving the distribution request message, the content distribution server (CDS), not the home agent (HA), multicasts the requested content and the address of the source device (here SP1) immediately before the home agent (HA). A pair with an address is managed as session information (distribution destination table). Note that “a tree has been created” means that session information corresponding to specific content is held in each of the above nodes.

(5) Stage of Content Relay and Multicast Distribution The content distribution server (CDS), which is a mobile IP client, distributes requested content based on the held session information. In the above process, since SP1 is registered as the requested content distribution destination, the content is unicast-encapsulated to SP1 by unicast and stream-distributed (steps 20 and 21). The multicast control gateway (MCG1) determines that the content distribution server (CDS) has been authenticated, and transfers the unicast stream. This stream is transferred to the splitter (SP1) via the home agent (HA) (step 22).

  When receiving the unicast-encapsulated content stream, the stream receiving unit 24 of the splitter (SP1) performs transfer based on the session information managed by the session management unit 25. Here, since a session for the multicast control gateway (MCG2) is managed, the stream is delivered from the stream delivery unit 22 to the multicast control gateway (MCG2) (step 23).

  The stream receiver 12 of the multicast control gateway (MCG2) receives content from the splitter (SP1). Then, the multicast restoration unit 19 restores the content stream to multicast (step 24), and the stream delivery unit 11 delivers the content based on the session information managed by the session management unit 152 (step 25). Here, since the session for the area where the client exists is managed, the content stream is distributed from the stream distribution unit 11 to the area using a multicast channel.

  In the above sequence example, there is one SP, but there may be no SP, or two or more SPs may exist.

  Further, the content distribution server (CDS) may not have a mobile IP function. In this case, the IP address of the content distribution server (CDS) is registered in the AMS, and packets transmitted from the content distribution server (CDS) and packets addressed to the content distribution server (CDS) do not pass through the HA. The other processes are the same as when the mobile IP function is provided.

(Client authentication)
Hereinafter, the authentication check process of the content reception client in the (3) content reception request process will be described in detail with reference to the sequence chart of FIG. By this processing, only authenticated clients can request distribution of multicast.

(3.1) Log-in of Content Receiving Client First, a client who is going to make a content distribution request is authenticated. The authentication method is not limited to a specific method. For example, if the client has a mobile IPv6 function, the home agent (HA) authenticates the client by the mobile IP function, and if the authentication is OK, the home agent (HA) uses the client's global IP address (home address). Is notified to the HA communication unit 10 of the multicast control gateway (MCG2), and the HA communication unit 10 notifies the HA to the authentication state management unit 151. The authentication state management unit 151 stores the address as the address of the authenticated client. Store and manage. In addition, even when the client does not have the mobile IP function, the client can access the home agent (HA) by providing the home agent (HA) with the function of authenticating the client without the mobile IP function. A home agent (HA) can perform authentication.

  Further, authentication may be performed by performing IPsec negotiation between the client and the multicast control gateway (MCG2), and the multicast control gateway (MCG2) may acquire the address of the authenticated client. Alternatively, the multicast control gateway (MCG2) may provide an authentication WWW page to the client, receive the input of the ID and password from the client, and authenticate the client by comparing with an ID and password registered in advance.

  In the example shown in FIG. 8, the home agent (HA) authenticates the client (step 31), and notifies the multicast control gateway (MCG2) of the global IP address of the client that has been successfully authenticated (step 32). The authentication status management unit 151 is notified (step 33).

Then, the multicast control gateway (MCG2) accesses the client using the acquired IP address (step 34), thereby acquiring the client MAC address, and the authentication state management unit 151 sets the acquired MAC address as the IP address. It manages in association (steps 35 and 36).
(3.2) Content reception request (multicast join)
In order to request multicast distribution, the client sends Join (IGMP Report for IPv4 multicast, MLD Report for IPv6 multicast). FIG. 8 shows the case of IPv6 multicast.

  In the case of IPv4 multicast, the authentication check unit 17 of the multicast control gateway (MCG2) uses the IP address in which the combination of the source IP address and the MAC address of the IGMP Report is held by the process (3.1). And whether it matches one of the MAC address pairs. If there is no match, the join is discarded. If they match, multicast distribution is performed by performing the processing from step 16 in FIG. When a content attribute request is made and a response indicating that the content can be distributed to the requested area is received, the packet filter unit 18 opens a distribution filter for the area of the content.

  On the other hand, in the case of IPv6 multicast, since the source IP address of the MLD Report is a link local address, it is not possible to check the match with the global IP address as in the case of IPv4 multicast. Therefore, in this embodiment, it is checked whether the MLD Report is a packet from an authenticated client as follows.

  As shown in FIG. 8, first, the authentication check unit 17 of the multicast control gateway (MCG2) acquires a source MAC address (referred to as MAC1) from the MLD Report packet received from the client (steps 37 and 38), It is checked whether the MAC1 matches any of the information acquired and managed in the step (3.1). If there is no match, the distribution request is discarded.

If there is a MAC address that matches MAC1, the authentication check unit 17 acquires a global IP address corresponding to MAC1 from the authentication state management unit 151 (steps 39 and 40). Then, the IP address acquired from the authentication state management unit 151 is set as the target address in the IPv6 Neighbor Solicitation packet, and the Neighbor Solicitation packet is transmitted to the client side area (step 41).
When a response packet (Neighbor Advertisement (neighbor advertisement)) is notified from the client having the IP address that has received this packet (step 42), the MAC address of the packet (referred to as MAC2) is checked. It is checked whether they match (step 43). When MAC2 matches MAC1, it can be determined that the client that transmitted the response packet is a client having an IP address held in association with MAC1, that is, an authenticated client. Accordingly, if MAC2 matches MAC1, it is determined that the client that has transmitted the MLD Report in step 37 is an authenticated client (step 44).
(3.3) Content distribution area check In response to the multicast distribution request accepted by the authentication check in (3.2), the multicast control gateway (MCG2) performs the same processing as steps 14 and 15 in FIG. A content distribution area check is performed (steps 45 to 49). If a response indicating that the distribution is possible is received, the filter of the packet filter unit 18 is opened (step 50 in FIG. 8). Thereafter, the processing from step 16 shown in FIG. 6 is performed to request content from the content distribution server (CDS), and the MCG 2 performs multicast distribution of the stream received by unicast to the request area (step 51).

(Mechanism for only authenticated clients to receive multicast content)
Next, a mechanism for allowing only authenticated clients to receive multicast content will be described. Here, the content stream is encrypted by distributing the encryption key (TEK) for encrypting and decrypting the content to the authenticated client and the multicast distribution server (CDS), and only the authenticated client is multicast. The content can be received. Also, an encryption key (KEK) for safely distributing TEK is distributed. The encryption key distribution process will be described below with reference to the sequence chart of FIG.

  In the example shown in FIG. 9, the multicast address for delivering content is M1, and the multicast address for multicast delivery of TEK is M2. The multicast key server (KS) of the multicast M1 securely distributes KEK to the authenticated clients by unicast by IPsec negotiation. Next, the encryption key (TEK) for the multicast M1 is encrypted with KEK and distributed by unicast. Thereafter, the TEK is updated at regular intervals, encrypted with KEK, and distributed to all the clients viewing and the distribution source (multicast M1 distribution content distribution server) of the multicast M1 using the multicast M2. The encryption key server (KS) unicast-encapsulates the multicast packet of the encryption key (TEK) and distributes it to the client group.

Hereinafter, the processing will be described in detail along the sequence of FIG. The content encryption key distribution scenario in the present embodiment includes (1) content attribute registration, (2) TEK distribution to a content distribution source, (3) content reception client authentication, (4) client authentication information notification, (5) It can be broadly divided into eight steps: a multicast M1 encryption key request from a client, (6) TEK distribution route creation, (7) TEK multicast distribution, and (8) TEK update. Hereinafter, each step will be described.
(1) Registration of content attributes First, a multicast content distribution source IP address and a multicast address M1 are registered in an address mapping server (AMS). In addition, information regarding the multicast encryption key server (KS) that distributes the TEK and KEK of the multicast content is also registered. That is, the IP address of the multicast encryption key server (KS) and the multicast address M2 for distributing the updated TEK are registered in the address mapping server (AMS). (The distribution source of M2 is KS.)
In the multicast encryption key server (KS), the IP address of the content distribution server (CDS) that is the content distribution source of the multicast address M1 is registered. That is, the same source IP address as the source IP address registered in AMS is registered.

Further, it is assumed that the content distribution server (CDS) is authenticated with respect to the MCG 1 and can communicate with other NW devices via the MCG 1.
(2) TEK Distribution to Content Distribution Source The content distribution server (CDS) requests an encryption key (TEK) for multicast M1 from the multicast encryption key server (KS) (step 61). The multicast encryption key server (KS) performs IPSEC negotiation with the content distribution server (CDS) in order to safely distribute TEK. At this time, the IP address of the content distribution server (CDS) is checked, and if it is the IP address of the multicast M1 distribution source, the ISAKMP SA is established. The content distribution server (CDS) further notifies the multicast encryption key server (KS) of the multicast address M1 of the requested content. The multicast encryption key server (KS) distributes KEK and TEK corresponding to the multicast address M1 using ISAKMP SA (step 62).
(3) Content Receiving Client Authentication Using the method described with reference to FIG. 8, the client that receives the content is authenticated (step 63). As a result of the authentication process, the multicast control gateway (MCG2) acquires the IP address and MAC address of the authenticated client and manages the IP address and MAC address as a pair in the authentication state management unit 151 (step 64).
(4) Client authentication information notification The IP address of the authenticated client is notified from the KS communication unit 9 of the multicast control gateway (MCG2) to the authentication information acquisition unit 41 of the multicast encryption key server (KS) (step 65). The authentication information management unit 421 of the multicast encryption key server (KS) manages this.
(5) Multicast M1 Encryption Key Request from Client The authenticated client requests the multicast key key (TEK) of the multicast M1 from the multicast encryption key server (KS) (step 66). The multicast encryption key server (KS) performs IPSEC negotiation with the authenticated client in order to securely distribute the TEK. At this time, the IP address of the client is checked, and if it is an authenticated client in the MCG 2, an ISAKMP SA is established (step 67). The client further notifies the multicast encryption key server (KS) of the multicast address M1 of the requested content. The multicast encryption key server (KS) distributes the TEK and KEK corresponding to the multicast address M1 to the client using ISAKMP SA (step 68).
(6) Creation of TEK Distribution Route When the authenticated client receives TEK and KEK for the multicast M1, it joins the multicast address M2 (step 69). On the other hand, the multicast M1 distribution source distribution server (CDS) also joins the multicast M2 (step 72). For these joins, the session information (distribution destination information) in KS is updated according to the procedure described with reference to FIGS. 7 and 8, and the unicode from the multicast encryption key server (KS) that is the distribution source of M2 is updated. A cast encapsulated stream delivery path is created (steps 70, 71, 73, 74, 75).

Thereafter, the client transmits a content distribution request message to the MCG 2 (step 76), and the content is transmitted from the content distribution server (CDS) according to the procedure described with reference to FIGS. 7 and 8 (steps 77 to 84). ). Here, the content is encrypted by TEK, and the client decrypts it using TEK (step 85). As a result, only the authenticated client holding the TEK can receive the multicast content. Step 69 to step 75 may be after step 76 to step 85.
(7) TEK multicast distribution The encryption key creation unit 45 of the multicast encryption key server (KS) updates the TEK at regular intervals (step 86). The multicast encryption key distribution unit 46 of the multicast encryption key server (KS) encrypts the updated TEK by using an algorithm such as 3DES using KEK, and sends a multicast packet for transmitting the encrypted data at the multicast address M2. create. The unicast capsule unit 47 of the multicast encryption key server (KS) unicast-encapsulates the multicast packet and unicasts it through the TEK delivery route (steps 87, 88, 91).
(8) TEK update The unicast packet is restored to the multicast M2 by the multicast control gateway (MCG2) (step 89), distributed to the client (step 90), and sent to the multicast M2 by the multicast control gateway (MCG1). It is restored and distributed to the content distribution server (CDS) (steps 92 and 93). Thereafter, the content distribution server (CDS) of the M1 distribution source can distribute the content by multicast M1 using the new TEK (steps 94 to 99). Even if the old TEK has been decrypted by a malicious client, only the authenticated client can decrypt and view the content by distributing the content using the new TEK. In addition, the multicast encryption key server (KS) can distribute the TEK to all authenticated clients viewing the multicast content and the distribution server by one transmission, and the load of TEK management is reduced. It is reduced.

  In the above process, an attribute is assigned to the authenticated client, and the multicast encryption key server (KS) uses an encryption key for encrypting and decrypting the multicast stream according to the attribute value for each multicast channel. It is also possible to determine whether to distribute.

  In this case, the client authentication unit 20 of the multicast control gateway (MCG) has an attribute value corresponding to the client ID as a database. For example, a client with a client ID “User1” at the time of authentication is assumed to have a client attribute value “1”. On the other hand, the authentication check unit 44 of the multicast encryption key server (KS) has a client attribute value list that permits encryption key distribution for each multicast channel.

  In the above-described (3) content reception client authentication stage, when the client is authenticated, the multicast control gateway (MCG2) collectively manages client attributes in addition to the IP address and MAC address of the client. At the stage of (4), when the client authentication information is notified from the MCG 2 to the KS, the IP address and its client attribute value are notified. When the multicast address M1 of the requested content is notified, the authentication check unit 44 of the multicast encryption key server (KS) includes the attribute value of the client in the client attribute value list that permits distribution of the encryption key for M1. If it is included in the list, the M1 TEK and KEK are distributed. Otherwise, the request from the client is rejected.

(Concrete example)
Next, the basic processing contents will be described more specifically using the network configuration shown in FIG. In the network shown in FIG. 10, it is assumed that each network device (device that relays a packet in the network) communicates using IPv6 and is assigned an IPv6 address as shown in FIG.

  That is, areas 1 that correspond to prefixes 2001: 0: 1: 1 :: / 64, areas 2 that correspond to 2001: 0: 1: 2 :: / 64, and 2001, as areas that can be wirelessly accessed by clients. There is an area 3 corresponding to: 2: 1: 1 :: / 64. 2001: 0: 1: 1 :: / 64 and 2001: 0: 1: 2 :: / 64 are subordinate to the multicast control gateway (MCG1), and 2001: 2: 1: 1 :: / 64 is the multicast control gateway. It is under (MCG2).

  The address on the unicast network side (Internet side) of the multicast control gateway (MCG1) is 2001: 1: 1: 1 :: 2. On the other hand, the unicast network side (Internet side) address of the multicast control gateway (MCG2) is 2001: 2: 2: 1 :: 2.

  The address of the home agent (HA) is 2001: 9: 9: 9 :: 2. The content distribution server 1 (CDS1) is a mobile IPv6 client, and its home address is 2001: 9: 9: 9 :: 10. Further, since the content distribution server 1 (CDS1) exists in the area 1 corresponding to 2001: 0: 1: 1 :: / 64 in the state shown in FIG. 10, its care-of address is 2001: 0: 1: 1 ::. This care-of address is notified to the home agent (HA) using the mechanism of Mobile IPv6.

  The address mapping server (AMS) has an address of 2001: 8: 8: 8 :: 2, and holds the content attribute information shown in FIG. In the content attribute information, the content distribution server 1 (CDS1) distributes content to the multicast address ff08 :: 1: 1, and the content corresponding to the multicast address ff08 :: 1: 1 is the multicast control gateway (MCG2). ) Distribution to several areas including the subordinate prefix 2001: 2: 1: 1 :: / 64 network is permitted. In addition, it is set whether or not a client requesting content distribution needs to be authenticated. In the case of “necessary”, the content attribute is provided when the content attribute request message includes information indicating that the client who has requested the content distribution is authenticated.

  The multicast control gateways (MCG1 and MCG2) read and recognize from the configuration file that an address mapping server (AMS) that manages such multicast content attributes exists in 2001: 8: 8: 8 :: 2. Suppose that

  Next, operations from the start of content request to the start of multicast distribution in the configuration of FIG. 10 will be described.

  Here, it is assumed that the multicast distribution server 1 (CDS1) exists in 2001: 0: 1: 1 :: / 64 under the multicast control gateway (MCG1) and has been authenticated. In addition, it is assumed that the client 1 requesting the content has already been authenticated. First, when the client 1 requests content corresponding to the multicast address ff08 :: 1: 1, the content reception client detection unit 16 of the multicast control gateway (MCG2) receives a request message (MLD Report) from this client. Then, when it is checked in the procedure described with reference to FIG. 8 that the request message is sent from an authenticated client, the multicast control gateway (MCG2) acquires the attribute of the requested multicast content. The content attribute request message is transmitted from the content attribute request unit 13 to the address mapping server (AMS).

  FIG. 12 shows an example of the content attribute request message. As shown in FIG. 12, the content attribute request message is distributed in addition to the multicast address of the content requesting distribution and the network prefix of the distribution destination (in this case, 2001: 2: 1: 1 :: / 64). The result of the authentication check of the client requesting

  The content attribute request receiving unit 31 of the address mapping server (AMS) that has received this notifies the AMS control unit 35 of this. The control unit 35 refers to the database (content attribute shown in FIG. 11), and the content corresponding to the requested multicast address can be distributed to the request source area 3, and the client who has made the distribution request has been authenticated. Is determined. As a result, the content attribute transmission unit 32 of the address mapping server (AMS) notifies the multicast control gateway (MCG2) of the content attributes shown in FIG.

  The stream distribution request unit 14 of the multicast control gateway (MCG2) uses the content attribute to send to the content distribution server 1 (CDS1) (2001: 9: 9: 9 :: 10) as shown in FIG. A message requesting the content of the address (ff08 :: 1: 1) is transmitted.

  Since the content distribution server 1 (CDS1) is a mobile IPv6 client, the request message is received by the home agent (HA). The home agent (HA) transfers this message to the content distribution server 1 (CDS1) (care-of address 2001: 0: 1: 1 :: abcd).

  FIG. 15 shows the transfer route of the content distribution request message. Upon receiving the content distribution request message from the multicast control gateway (MCG2) transferred from the home agent (HA), the content distribution server 1 (CDS1) creates a content distribution session for the multicast control gateway (MCG2).

  Then, the content distribution server 1 (CDS1) unicasts the multicast content corresponding to ff08 :: 1: 1 distributed to the multicast control gateway (MCG2), and transmits this to the multicast control gateway (MCG2). Since the content distribution server 1 (CDS1) is a mobile IPv6 client, the stream from the content distribution server 1 (CDS1) to the multicast control gateway (MCG2) is transferred via the home agent (HA). FIG. 16 shows a stream distribution route.

  When the stream receiving unit 12 of the multicast control gateway (MCG2) receives the content, the multicast restoring unit 19 of the MCG2 restores the content corresponding to ff08 :: 1: 1 from the unicast packet to the multicast packet. Based on the session information, the stream distribution unit 11 performs multicast distribution of the content toward the area 3 where the client 1 exists.

  Here, the content distribution server 1 (CDS1) has moved from the network area 1 corresponding to 2001: 0: 1: 1 :: / 64 to the network area corresponding to 2001: 0: 1: 2 :: / 64. And The content distribution server 1 (CDS1) is a mobile IPv6 client and the home address remains unchanged at 2001: 9: 9: 9 :: 10, but in the area 2 corresponding to 2001: 0: 1: 2 :: / 64 Since it exists, the care-of address changes to, for example, 2001: 0: 1: 2 :: abcd. At this time, the content distribution server 1 (CDS1) notifies the home agent (HA) of this care-of address using the mechanism of Mobile IPv6. In addition, the content distribution server 1 (CDS1) is authenticated by the home agent (HA). Since AMS manages the home address of content distribution server 1 (CDS1), the address of content distribution server 1 (CDS1) managed by AMS does not require any change.

  At this time, in response to the multicast ff08 :: 1: 1 request from the client 1, the stream request message transmitted by the MCG 2 is sent to the home agent at the correct location of the content distribution server 1 (CDS1) as shown in FIG. (HA). Further, the stream distribution route from the content distribution server 1 (CDS1) is the route shown in FIG. Thereby, the multicast control gateway (MCG2) and the multicast clients under its control can continue to receive the multicast content (ff08 :: 1: 1) without being aware of the movement of the content distribution server 1 (CDS1).

(When encrypting a multicast stream)
Next, a specific example of the encryption key distribution process described in FIG. 9 will be described using the network configuration shown in FIG.

  In this network, as in the above specific example, each network device communicates using IPv6, and has the same network configuration as in FIG. 10, and is assigned an IPv6 address as shown in FIG. To do. However, in the configuration of FIG. 19, in addition to the configuration of FIG. 10, there is an encryption key server (KS) that creates and distributes a multicast encryption key, and its address is 2001: 8: 8: 8 :: 3. And

  The content distribution server (CDS1) distributes multicast content of ff08 :: 1: 1 (corresponding to M1 in FIG. 9), and the multicast encryption key server (KS) uses the multicast encryption keys (TEK and KEK). Manage and distribute Further, when this TEK is updated, the multicast address for multicast distribution to the content distribution server (CDS1) and all receiving clients is assumed to be ff08 :: 3: 1: 1 (corresponding to M2 in FIG. 9). In this case, as shown in FIG. 20, a distribution source server for each multicast channel is registered in the address mapping server. Hereinafter, the content distribution server (CDS1) and the client 1 have been authenticated with respect to the multicast control gateway (MCG1) and the multicast control gateway (MCG2), respectively, and the KS communication of the multicast control gateway (MCG1) and the multicast control gateway (MCG2). Assume that the authentication information acquisition unit 41 of the KS has been authenticated from the unit 9 and the IP address has been notified. It is also assumed that the content distribution server (CDS1) is registered in the KS authentication information management unit 421 that it is a distribution source server of ff08 :: 1: 1.

  First, the content distribution server (CDS1) requests TEk and KEK of ff08 :: 1: 1 from the multicast encryption key server (KS) in order to receive TEK of ff08 :: 1: 1. The multicast encryption key server (KS) distributes TEK and KEK because the source IP address of this request message is already managed in the authentication information management unit 421 of the multicast encryption key server (KS).

  Further, when the content distribution server (CDS1) joins the multicast channel ff08 :: 3: 1: 1 for receiving the updated TEK, the content reception client detection unit 16 of the multicast control gateway (MCG1) A Join message (MLD Report) is received from this client. The multicast control gateway (MCG1) transmits a content attribute request message from the content attribute request unit 13 to the AMS in order to acquire the attribute of the requested multicast channel. The content attribute request message includes a distribution destination network prefix (in this case, 2001: 0: 1: 1 :: / 64) as shown in FIG. The content attribute request receiving unit 31 of the address mapping server (AMS) that has received this notifies the AMS control unit 35 of this. The control unit refers to the database (content attribute shown in FIG. 20) and determines that the requested multicast channel can be distributed to the request source area. As a result, the content attribute transmission unit 32 of AMS notifies the multicast control gateway (MCG1) of the content attributes shown in FIG. The stream distribution request unit 14 of the MCG 1 uses the content attribute to point to the multicast encryption key server KS (2001: 8: 8: 8 :: 3), and the multicast address (ff08 :: 3: Send a message requesting the 1: 1) stream. When receiving the stream delivery request message from the multicast control gateway (MCG1), the multicast encryption key server (KS) creates a stream delivery session for the multicast control gateway (MCG1).

  Similarly, the client 1 requests TEk and KEK of ff08 :: 1: 1 from the multicast encryption key server (KS) in order to receive the TEK of ff08 :: 1: 1. The multicast encryption key server (KS) distributes TEK and KEK because the source IP address of this request message is already managed in the authentication information management unit 421 of the multicast encryption key server (KS). Further, when the client 1 joins the multicast channel ff08 :: 3: 1: 1 for receiving the updated TEK, the content reception client detection unit 16 of the multicast control gateway (MCG2) A Join message (MLD Report) is received. The multicast control gateway (MCG2) transmits a content attribute request message from the content request unit 13 to the AMS in order to acquire the attribute of the requested multicast channel. The content attribute request message includes a distribution destination network prefix (in this case, 2001: 2: 1: 1 :: / 64) as shown in FIG.

  Upon receiving this, the AMS content attribute request receiving unit 31 notifies the AMS control unit 35 of this. The control unit 35 refers to the database (content attribute in FIG. 20) and determines that the requested multicast channel can be distributed to the request source area. As a result, the AMS content attribute transmission unit 32 notifies the multicast control gateway (MCG2) of the content attributes shown in FIG. The stream delivery requesting unit 14 of the multicast control gateway (MCG2) uses the content attribute to send KS (2001: 8: 8: 8 :: 3) to the multicast address (ff08 :: 3: shown in FIG. 26). Send a message requesting the 1: 1) stream. When receiving the stream delivery request message from the multicast control gateway (MCG2), the multicast encryption key server (KS) creates a stream delivery session for the multicast control gateway (MCG2). FIG. 27 shows the transfer route of the stream delivery request message described above. Further, as a result of the distribution request, TEK is distributed through a route as shown in FIG.

  The procedure in which the client 1 requests the content of the multicast address ff08 :: 1: 1 and distributes it from the content distribution server (CDS1) is the same as the procedure already described with reference to the configuration of FIG. The content distribution server (CDS1) encrypts the content using this TEK, and performs multicast distribution with a multicast address of ff08 :: 1: 1. On the other hand, when the client that has acquired the TEK receives multicast content encrypted with the TEK, the client can decrypt with the same TEK.

  Next, an example in which attributes are assigned to an authenticated client will be described. In this case, it is assumed that the client authentication unit 20 of the multicast control gateway (MCG2) has an attribute value corresponding to the client ID as shown in FIG. 29 as a database. Further, as shown in FIG. 29, the client 1 is assumed that the client ID at the time of authentication is “User1”, and the client attribute value of the client 1 is “1”.

  On the other hand, it is assumed that the authentication check unit 17 of the multicast encryption key server (KS) has a list shown in FIG. 30 as a client attribute value list that permits encryption key distribution for each multicast address.

  At this time, the client 1 requests the multicast key of the multicast address ff08 :: 1: 1 from the multicast encryption key server (KS). The multicast encryption key server (KS) can distribute TEK and KEK because the attribute value of the client 1 is “1” and “1” is included in the encryption key distribution permission list of ff08 :: 1: 1. Judge. Similarly, if the client 2 authenticates with “User4” as the client ID, the attribute value is “2”, which is not included in the list, so that the authenticated client 2 is ff08 :: 1: 1. Even if an encryption key is requested, the multicast encryption key server (KS) rejects it.

  As described above, according to the multicast distribution system described in the present embodiment, by setting the database in the address mapping server, the content distribution server and the content distribution destination area can be specified for each content. It is possible to reflect a policy that contents are multicast-distributed only to clients in the network, and it is possible to dynamically construct a content distribution tree according to this policy.

  Further, by distributing TEK and KEK to the authenticated client and the content distribution server (CDS), only the authenticated client can receive specific content.

  The present invention is not limited to the above-described embodiments, and various modifications and applications can be made within the scope of the claims.

It is a figure which shows an example of the multicast delivery system in a prior art. It is a figure which shows the multicast delivery system in embodiment of this invention. It is a functional block diagram of the multicast control gateway in the embodiment of the present invention. It is a functional block diagram of the splitter in the embodiment of the present invention. It is a functional block diagram of the address mapping server in the embodiment of the present invention. It is a functional block diagram of the multicast encryption key server in the embodiment of the present invention. It is a figure which shows the sequence from the authentication of a client and a content delivery server in the embodiment of this invention to the multicast delivery start of a content. It is a sequence chart for demonstrating the authentication check process of a content reception client. It is a sequence chart which shows the process of encryption key distribution. It is a figure which shows in detail the multicast delivery system in embodiment of this invention. It is an example of the content attribute information which the address mapping server in embodiment of this invention hold | maintains. It is a figure which shows an example of the content of the content attribute request message in embodiment of this invention. It is a figure which shows an example of the content of the content attribute message transmitted from the address mapping server in embodiment of this invention. It is a figure which shows an example of the content of the stream delivery request message in embodiment of this invention. It is a figure which shows the transfer path | route of the stream delivery request message corresponding to a multicast address (ff08 :: 1: 1). It is a figure which shows the stream delivery path | route corresponding to a multicast address (ff08 :: 1: 1). It is a figure which shows the transfer path | route of the stream delivery request message after a content delivery server moves. It is a figure which shows the stream delivery path | route after a content delivery server moved. It is a figure which shows in detail the multicast delivery system for demonstrating the distribution process of an encryption key. It is an example of the content attribute information which the address mapping server in embodiment of this invention hold | maintains. It is a figure which shows an example of the content of the content attribute request message in embodiment of this invention. It is a figure which shows an example of the content of the content attribute message transmitted from the address mapping server in embodiment of this invention. It is a figure which shows an example of the content of the TEK multicast delivery request message in embodiment of this invention. It is a figure which shows an example of the content of the content attribute request message in embodiment of this invention. It is a figure which shows an example of the content of the content attribute message transmitted from the address mapping server in embodiment of this invention. It is a figure which shows an example of the content of the TEK multicast delivery request message in embodiment of this invention. It is a figure which shows the transfer path | route of the TEK multicast delivery request message corresponding to a multicast address (ff08 :: 3: 1: 1). It is a figure which shows the TEK multicast delivery path | route corresponding to a multicast address (ff08 :: 3: 1: 1). It is an example of the client attribute value which a multicast control gateway (MCG2) manages. It is an example of an encryption key distribution permission list managed by a multicast encryption key server (KS).

Explanation of symbols

1, 3 Multicast router 5 Client AMS address mapping server HA Home agent CDS Content distribution server SP Splitter MCG Multicast control gateway KS Multicast encryption key server 9 KS communication unit 10 HA communication unit 11 Stream distribution unit 12 Stream reception unit 13 Stream distribution request Unit 14 content attribute request unit 15 control unit 16 content reception client detection unit 17 authentication check unit 18 packet filter unit 19 multicast restoration unit 20 client authentication unit 21 content request reception unit 22 stream distribution unit 23 stream distribution request unit 24 stream reception unit 25 Control unit 31 Content attribute request reception unit 32 Content attribute transmission unit 33 Content attribute management database 34 Attribute operation The user interface unit 35 control unit 41 the authentication information acquisition unit 42 control unit 43 encryption key request receiving unit 44 authentication check unit 45 encryption key creation portion 46 multicast encryption key distribution unit 47 unicast capsule part

Claims (4)

An encryption key distribution device for multicast distribution of a content encryption key for encrypting and decrypting predetermined multicast content,
Holding means for holding the address of the authenticated client;
A content distribution device encryption key transmission means for transmitting the content encryption key and a key encryption key for encrypting and decrypting the content encryption key to a content distribution device for distributing the multicast content;
When a key request and a multicast address of the multicast content are received from a client, and the address of the source of the key request is the address of the authenticated client, the content encryption key and the client A client encryption key transmission means for transmitting a key encryption key via an encrypted communication path ;
After receiving a multicast distribution request for the content encryption key from the content distribution device, and further receiving a multicast distribution request for the content encryption key from the client, the content encryption key is updated at regular intervals. Multicast distribution in which the updated content encryption key is encrypted with the key encryption key, and the encrypted content encryption key is multicast distributed to the area where the content distribution apparatus exists and multicast distribution to the area where the client exists And an encryption key distribution device. The multicast distribution means includes
When receiving the multicast delivery request for the content encryption key, multicast information for multicast delivery of the content encryption key and the information on the destination of the updated content encryption key corresponding to the area of the multicast delivery request transmission source device Holds session information associated with addresses,
The encryption key distribution device according to claim 1, wherein when the content encryption key is updated, the updated content encryption key is multicast-distributed based on the session information. The encryption key distribution device holds, for each multicast content, a list of client attribute values that can distribute the content encryption key,
The encryption key distribution device receives an address of the authenticated client and an attribute value corresponding to the client from an authentication device that authenticates the client, and the holding unit associates the address with the attribute value. Hold
The client encryption key transmission means receives the key request and the multicast address of the multicast content, the address of the key request source is the address of the authenticated client, and an attribute corresponding to the address The encryption key according to claim 1, wherein when the value is included in the attribute value list as an attribute value corresponding to the multicast content, the content encryption key and the key encryption key are transmitted to the client. Distribution device. A program for causing a computer to realize the function of an encryption key distribution device for multicast distribution of a content encryption key for encrypting and decrypting predetermined multicast content, the computer comprising:
Means for accessing a storage device holding the address of the authenticated client;
A content distribution device encryption key transmission means for transmitting the content encryption key and a key encryption key for encrypting and decrypting the content encryption key to the content distribution device for distributing the multicast content;
When a key request and a multicast address of the multicast content are received from a client, and the address of the source of the key request is the address of the authenticated client, the content encryption key and the client Client encryption key transmission means for transmitting a key encryption key and an encrypted communication path ,
After receiving a multicast distribution request for the content encryption key from the content distribution device, and further receiving a multicast distribution request for the content encryption key from the client, the content encryption key is updated at regular intervals. Multicast distribution in which the updated content encryption key is encrypted with the key encryption key, and the encrypted content encryption key is multicast distributed to the area where the content distribution apparatus exists and multicast distribution to the area where the client exists means,
Program to function as.

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