JP2004260556A - Office apparatus, subscriber apparatus, communication system, and encryption key notification method - Google Patents

Abstract

In a one-to-many network such as a PON, the encryption concealment of a multicast downlink signal is enhanced.
A station side device has a multicast encryption key generating means for generating a multicast encryption key for encrypting a message to be multicast to a subscriber side device, and the multicast encryption key is provided to each of the subscriber side devices. And an encryption circuit for generating an encrypted multicast encryption key encrypted with a unicast encryption key, which is a unique encryption key, and transmitting the encrypted multicast encryption key to the subscriber unit. [Selection] Fig. 6

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a station-side device, a subscriber-side device, a communication system, and an encryption key notification method in a one-to-many network such as a Passive Optical Network (PON) architecture.
[0002]
[Prior art]
The conventional Ethernet (registered trademark) network configuration includes a one-to-one configuration, a bus configuration, a ring configuration, and the like. However, all of them accommodate a LAN and are not expected to be applied to an access network.
Here, when the network form is PON and application to an access system is considered, encryption is required for a downlink signal. Considering the VLAN (Virtual LAN) function of the EPON (Ethernet (registered trademark) PON) system, individual encryption is required for unicast and multicast.
[0003]
For example, in an ATM-PON system defined by ITU-T 983.1 having a PON architecture similar to EPON, a unicast encryption key generated by an ONT (Optical Network Termination) transmission device is converted to an OLT (Optical Line Termination). It describes that the transmission device is periodically notified and updated.
According to Japanese Patent Application Laid-Open No. H11-215146, two types of encryption keys for unicast and multicast are stored in advance in an ONT transmission device and an OLT transmission device, and a unicast key is used for unicast transmission and a multicast key is used for multicast transmission. Is used to perform communication (see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-11-215146
[Problems to be solved by the invention]
[0005]
When the Ethernet (registered trademark) network mode is PON and the application to an access system is considered, encryption is required for a downlink signal. In the ATM-PON system described in Japanese Patent Application Laid-Open No. H11-215146, two types of encryption keys for unicast and multicast are stored in advance in an ONT transmission device and an OLT transmission device. In some cases, communication is performed by encrypting using a multicast key, and there is a problem that the data can be decrypted by a relatively simple encryption method.
[0006]
Also, the update of the multicast encryption key is performed according to ITU-TG. If an attempt is made to perform the same method as the encryption key update method for unicast data specified in 983.1, multicast data is copied as unicast data as much as one piece of data is transmitted by multicast, and the bandwidth is compressed. There is a problem of doing.
[0007]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to enhance cryptographic concealment of multicast data.
[0008]
[Means for Solving the Problems]
An office apparatus according to the present invention is connected to a plurality of subscriber apparatuses, and a multicast encryption key generating means for generating a multicast encryption key for encrypting a message to be multicast to the subscriber apparatus. An encryption key for multicast is generated by encrypting the encryption key for multicast with a unicast encryption key which is a unique encryption key for each of the subscriber side devices, and the encrypted multicast encryption key is stored on the subscriber side. It has an encryption circuit for transmitting to the device.
[0009]
Further, the subscriber unit according to the present invention is a subscriber unit that receives an encrypted message transmitted from the station unit, and joins a multicast domain for the station unit together with other subscriber units. A unicast encryption device for storing a unicast encryption key unique to the subscriber device used when the station device encrypts and unicasts a message to the subscriber device. Key holding means, a unicast encryption key transmitting means for transmitting the unicast encryption key to the optical line terminal, and a multicasting key used for encrypting a message to be multicast by the optical line terminal in the multicast domain. An encryption key that encrypts the encryption key with the unicast encryption key transmitted by the unicast encryption key transmission means. The encryption key cast received from the station side device, in which so as to have a decryption circuit for decrypting the encryption key for the unicast.
[0010]
An encryption key notifying method according to the present invention is a method for notifying an encryption key from a station device to a subscriber device in a communication system including a station device and a plurality of subscriber devices connected to the station device. In addition, the method has the following steps (1) to (4).
(1) The subscriber-side device transmits a unicast encryption key, which is an encryption key unique to the subscriber-side device used when the station-side device unicasts a message to the subscriber-side device, as described above. Transmitting a unicast encryption key to be transmitted to the optical line terminal;
(2) a multicast encryption key generating step in which the station apparatus generates a multicast encryption key that is an encryption key used when multicasting a message to the plurality of subscriber apparatuses;
(3) The station-side device encrypts the generated multicast encryption key with the unicast encryption key transmitted from the subscriber device to generate an encrypted multicast encryption key, and Generating and transmitting an encryption key for encrypted multicast to be transmitted to
(4) A multicast encryption key decryption step in which the subscriber device decrypts the transmitted encrypted multicast encryption key with the unicast encryption key of the subscriber device.
[0011]
In the encryption key notifying method according to the present invention, in the encrypted multicast encryption key generation and transmission step, the station apparatus transmits the encrypted multicast encryption key in association with an identifier unique to each subscriber apparatus. In the multicast encryption key decrypting step, the subscriber device decrypts the encrypted multicast encryption key associated with the identifier of the subscriber device with the unicast encryption key of the subscriber device. It is intended to be.
[0012]
Further, in the encryption key notifying method according to the present invention, in the generating and transmitting step of the encrypted multicast encryption key, the station-side device may be configured such that the station apparatus is uniquely determined by a predetermined operation from the encrypted multicast encryption key and the multicast encryption key. In the multicast encryption key decryption step, the subscriber side device decrypts the encrypted multicast encryption key with the unicast encryption key of the subscriber side device and performs decryption unicast. A second constant is generated from the generated decryption multicast encryption key by the predetermined operation, and when the first constant and the second constant match, the decryption multicast encryption key is generated. The key is determined to be the multicast encryption key.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a communication system according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an OLT (Optical Line Termination) transmission device, 2 denotes an optical coupler, 3 denotes an optical fiber, 4 denotes an ONT (Optical Network Termination) transmission device, and a plurality of ONT transmission devices 4 (ONT transmission devices # 1 to # 1). #N) is connected to one OLT transmission apparatus 1 via the optical fiber 3 and the optical coupler 2.
In a system such as this embodiment, the OLT transmission apparatus 1 is generally called an EPON-OLT, and the ONT transmission apparatus 4 is also called an EPON-ONT.
The OLT transmission apparatus 1 is a station apparatus in the present invention, and each ONT transmission apparatus 4 is a subscriber apparatus in the present invention, and a communication system is configured by the station apparatus and the subscriber apparatus.
In addition, each ONT transmission device 4 is identified by an ID (identifier) assigned individually.
[0014]
Next, the configuration of the OLT transmission apparatus 1 will be described with reference to FIG.
In the following description, the multicast encryption key is an encryption key used when the OLT transmission apparatus 1 encrypts and multicasts a message to the ONT transmission apparatus 4 in a predetermined multicast domain. The encryption key is an encryption key used when the OLT transmission apparatus 1 encrypts and transmits a message to one specific ONT transmission apparatus 4.
The OLT 1 and the ONT transmission device 4 in the multicast domain share the multicast encryption key, and each ONT 4 decrypts the message encryption encrypted by the OLT 1 with the multicast encryption key using the same multicast encryption key.
Similarly, the OLT 1 and the specific ONT transmission device 4 share the unicast encryption key, and the ONT 4 decrypts the message encryption encrypted by the OLT 1 with the unicast encryption key using the same unicast encryption key. I do.
[0015]
The OLT transmission apparatus 1 includes an encryption control frame extraction unit 5, a unicast encryption key holding unit 6, a multicast encryption key holding unit 7, a multicast encryption key generation unit 8, an encryption circuit 9, and an encryption control frame insertion unit 10.
In FIG. 2, reference numeral 11 denotes a downlink input signal, 12 denotes a new multicast encryption key notification signal, 13 and 15 denote multicast encryption key signals, 14 denotes a downlink signal, 16 denotes a PON downlink signal, and 17 denotes a unicast encryption key signal. , 18 is a PON uplink signal, 19 is a unicast encryption key extraction signal, 20 is an uplink output signal, 21 is a unicast encryption key reception completion signal, 22 is a unicast encryption key search signal, and 23 is a multicast encryption key. This is a search signal.
[0016]
Next, the configuration of the ONT transmission device 4 will be described with reference to FIG.
The ONT transmission apparatus 4 includes an encryption control frame insertion unit 101, a unicast encryption key generation unit 102, a multicast encryption key holding unit 103, an encryption control frame extraction unit 104, a unicast encryption key holding unit 105, and an encryption / decryption circuit 106. Having.
In FIG. 3, reference numeral 107 denotes an uplink input signal, 108, 109, and 112 denote unicast encryption key signals, 110 denotes a PON uplink signal, 111 denotes a PON downlink signal, 113 denotes a multicast encryption key signal, 114 denotes a decrypted signal, 115 is a multicast encryption key extraction signal, 116 is a downstream output signal, and 117 is a unicast encryption key update completion notification signal.
The encryption control frame insertion means 101 corresponds to the unicast encryption key transmission means in the present invention.
[0017]
Next, the operation will be described.
First, a method of updating a unicast encryption key used for notification of a multicast encryption key will be described. FIG. 4 shows a procedure for updating a unicast encryption key.
[0018]
First, in one ONT transmission device 4 (for example, ONT transmission device # 1), the unicast encryption key generation unit 102 generates its own unicast encryption key. The generated unicast encryption key is notified to the encryption key control frame insertion unit 101 and the unicast encryption key holding unit 105 as unicast encryption key signals 108 and 109, respectively.
Upon receiving the unicast encryption key signal 108, the encryption control frame insertion means 101 generates an encryption control frame, inserts it into the uplink input signal 107, and transmits it as the PON uplink signal 110 to the OLT transmission apparatus 1 (unicast encryption Key transmission step).
This PON upstream signal is "new unicast encryption key notification" in FIG.
[0019]
On the other hand, the unicast encryption key holding unit 105 that has received the unicast encryption key signal 109 holds two keys, a new unicast encryption key and a current unicast encryption key. The generated new unicast encryption key is not notified yet.
[0020]
The OLT transmission apparatus 1 receives the signal transmitted by the ONT transmission apparatus 4 as the PON uplink signal 110 (see FIG. 3) as the PON uplink signal 18 (see FIG. 2). , Extracts the encryption control frame from the ONT transmission device 4 and notifies the unicast encryption key to the unicast encryption key holding means 6 as the unicast encryption key extraction signal 19 of the ONT transmission device 4 # 1.
The unicast encryption key holding unit 6 that has received the unicast encryption key extraction signal 19 holds and manages a unicast encryption key for each ONT transmission device 4 (# 1 to #n).
[0021]
Upon receiving the new unicast encryption key of the ONT transmission device 4 (# 1 in this example) from the unicast encryption key extraction signal 19, the unicast encryption key holding unit 6 transmits the unicast encryption key to the encryption control frame insertion unit 10. And outputs a new encryption key reception completion signal 21 to notify that a new unicast encryption key has been received.
The encryption control frame inserting means 10 inserts the encryption control frame into the downlink input signal 11 to notify the ONT transmission device 4 that updates the unicast encryption key of the update completion of the unicast encryption key. Is transmitted to the encryption circuit 9.
[0022]
In the encryption circuit 9, the encryption control frame for notifying the completion of the update of the encryption key for unicast is transmitted to the ONT transmission device as the PON downlink signal 16 in plain text without any encryption. This PON downlink signal 16 is “encryption key update confirmation” in FIG.
The unicast user data after the transmission of the unicast encryption key update completion notification encryption control frame by this “encryption key update confirmation” is encrypted by the encryption circuit 9 using the new unicast encryption key, and the ONT The data is transmitted to the transmission device 4.
[0023]
When the OLT transmission apparatus 1 transmits a packet to the ONT transmission apparatus 4 before transmitting the “encryption key update confirmation”, for example, when transmitting the “downlink packet a” in FIG. Encrypt with the old unicast encryption key and send.
[0024]
In the ONT transmission apparatus 4 (here, # 1), the encryption / decryption circuit 106 transmits the unicast encryption key update completion notification encryption control frame from the OLT transmission apparatus 1 (corresponding to “encryption key update confirmation” in FIG. 4). To receive. The encryption / decryption circuit 106 transmits the encryption control frame for unicast encryption key update completion notification in plain text, and transmits it to the encryption control frame extraction means 104 without decrypting it.
Upon extracting the encryption control frame for unicast encryption key update completion notification, the encryption control frame extraction unit 104 notifies the unicast encryption key update completion notification signal 117 to the unicast encryption key holding unit 105.
Upon receiving the unicast encryption key update completion notification signal 117, the unicast encryption key holding unit 105 notifies the encryption / decryption circuit 106 of the new encryption key, and the encryption / decryption circuit 106 updates the unicast encryption key.
The timing at which the ONT transmission device 4 updates the unicast encryption key of the encryption / decryption circuit 106 corresponds to the timing of “update new decryption key” in FIG.
[0025]
The OLT transmission apparatus 1 encrypts the unicast user data (for example, “downlink packet b” in FIG. 4) transmitted after updating the new encryption key with the new unicast encryption key, and the ONT transmission apparatus 4 updates the new decryption key. After that, the unicast user data such as the downlink packet b received above is decrypted with the new unicast encryption key.
[0026]
FIG. 5 is a diagram of a control frame format in the above operation.
In FIG. 5, the control frame format whose content is “notification of encryption key for unicast” is a control frame format transmitted from the ONT transmission device 4 to the OLT transmission device 1 in “notification of new encryption key for unicast” in FIG. The control frame format whose content is “confirmation of encryption key update for unicast” in FIG. 5 is the format of the control frame transmitted from the OLT transmission apparatus 1 to the ONT transmission apparatus 4 in “confirmation of encryption key update” in FIG. It is.
[0027]
The frame format of the unicast encryption key notification is such that an ID given to each source ONT transmission device 4 is stored in the preamble, a code appropriately selected from unused values is stored in Opcose, and a new data is stored in Data. Stores the unicast encryption key.
In the unicast encryption key update confirmation, the ID of the transmission destination ONT transmission device 4 is stored in the preamble, and a code appropriately selected from unused values is stored in Opcce.
In the figure, DA is the MAC address of the transmission destination in the abbreviation of “MAC Destination Address”, SA is the MAC address of the transmission source in the abbreviation of “MAC Source Address”, and FCS is the abbreviation of “Frame Check Sequence” in the frame. It is well known that this is an error detection code, and the same applies to the following description.
[0028]
The above operation is periodically performed between the ONT transmission device 4 and the OLT transmission device 1, and the unicast encryption key of each ONT transmission device 4 is updated.
[0029]
Next, a method of updating a multicast encryption key used when the OLT transmission apparatus 1 transmits an encrypted message within a predetermined multicast domain will be described.
FIG. 5 shows a multicast encryption key update procedure. Here, it is assumed that all of the ONT transmission apparatuses 4 (# 1 to #n) in FIG. 1 belong to the same multicast domain.
[0030]
First, in the OLT transmission apparatus 1 shown in FIG. 2, a multicast encryption key for VLAN is generated by the multicast encryption key generation means 8 (multicast encryption key generation step). This corresponds to "generation of a new encryption key for multicast" by the OLT transmission apparatus 1 in FIG.
The generated multicast encryption key (new multicast encryption key) is transmitted to the multicast encryption key holding means 7 by the multicast encryption key signal 13 and notified.
The multicast encryption key holding unit 7 holds and manages a new multicast encryption key.
Further, the multicast encryption key holding unit 7 transmits the new multicast encryption key to the encryption control frame insertion unit 10 by using the new multicast encryption key notification signal 12.
Upon receiving the new multicast encryption key notification signal 12, the encryption control frame inserting means 10 sends a multicast for notifying the ONT transmission device 4 in the multicast domain to which the new multicast encryption key is applied of the new multicast encryption key. The encryption key update notification frame is inserted into the downstream input signal 11 to generate the downstream signal 14.
[0031]
The encryption circuit 9 encrypts the new multicast encryption key with the current unicast encryption key of the ONT transmission device 4 whose key is to be updated, generates an encrypted multicast encryption key, and transmits it to the ONT transmission device 4 as a PON downlink signal 16. (Encryption / multicast encryption key generation / transmission step).
The transmission timing of the PON downlink signal 16 corresponds to “new encryption key update” in FIG. The multicast user data (for example, downlink packet c) multicast from the OLT transmission apparatus 1 to the ONT transmission apparatus 4 before the update of the new encryption key is encrypted with the “old multicast encryption key” before the update and transmitted. The multicast user data (for example, a downlink packet d) that is multicast from the OLT transmission apparatus 1 to the ONT transmission apparatus 4 after the “encryption key update” is encrypted with the updated “new multicast encryption key”.
[0032]
FIG. 7 is a diagram showing a control frame format in the new multicast encryption key notification of FIG.
The preamble stores the ID of the transmission destination ONT transmission device 4, the Opcode stores a value different from the value used for the unicast encryption key exchange in FIG. 5, and the Data indicates the ONT transmission device 4. A multicast encryption key encrypted with the unicast encryption key (working unicast encryption key) is stored.
[0033]
Each ONT transmission device 4 receives the encryption key update notification encryption control frame from the OLT transmission device 1. The encryption / decryption circuit 106 encrypts the multicast encryption key update notification encryption control frame with the current unicast encryption key, and thus decrypts using the current unicast encryption key (multicast encryption key). (Decryption step), and transmits to the encryption control frame extraction means 104.
[0034]
A new encryption key for multicast is extracted by the encryption control frame extraction means 104 and is notified to the encryption key holding means for multicast 103 by a multicast encryption key extraction signal 115.
The multicast encryption key holding means 103 updates and manages the multicast encryption key corresponding to the VLAN. The multicast user data after receiving the encryption key update notification encryption control frame is decrypted with the new multicast encryption key.
[0035]
In the above operation, the OLT transmission apparatus 1 individually transmits a new multicast encryption key notification to the ONT transmission apparatus 4 and notifies the ONT transmission apparatus 4 of the update of the new multicast encryption key. The OLT transmission apparatus 1 and each ONT transmission apparatus 4 perform the above operation periodically at a predetermined timing to update the multicast encryption key.
In the above description, the timing at which the unicast encryption key and the multicast encryption key are updated may be determined at predetermined time intervals using a timer, or between the OLT transmission device 1 and the ONT transmission device 4. It may be updated each time the communication amount (the number of bits or the number of packets) reaches a predetermined amount. This is the same in the following embodiments.
[0036]
As described above, by updating not only the unicast encryption key but also the multicast encryption key periodically, even if a relatively simple encryption technology is applied, the multicast data in the broadcast (broadcast) communication architecture can be obtained. There is an effect that the concealment of the data can be enhanced.
[0037]
Embodiment 2 FIG.
In the first embodiment, the example in which the OLT transmission apparatus 1 individually transmits the multicast encryption key notification to each ONT transmission apparatus 4 has been described. An example of simultaneous transmission to the ONT transmission device 4 will be described.
[0038]
The configuration of the communication system and the configurations of the OLT transmission apparatus and the ONT transmission apparatus according to this embodiment are the same as those shown in FIGS.
Also, the procedure for updating the unicast encryption key of each ONT transmission apparatus is the same as the procedure described in the first embodiment with reference to FIGS. 4 and 5, and a description thereof will be omitted.
[0039]
In the first embodiment, since the OLT transmission apparatus 1 individually notifies the new multicast encryption key notification (FIG. 6) to the ONT transmission apparatus 4, the control frame format of the new multicast encryption key notification (FIG. 7) Contains only the multicast encryption key encrypted with the unicast encryption key of one transmission destination ONT transmission device.
[0040]
As in the first embodiment, a multicast encryption key for VLAN is generated by the multicast encryption key generation means 8 in the OLT transmission apparatus 1. This corresponds to "generation of a new encryption key for multicast" by the OLT transmission apparatus 1 in FIG.
The generated multicast encryption key (new multicast encryption key) is transmitted to the multicast encryption key holding means 7 by the multicast encryption key signal 13 and notified.
The multicast encryption key holding unit 7 holds and manages a new multicast encryption key.
Further, the multicast encryption key holding unit 7 transmits the new multicast encryption key to the encryption control frame insertion unit 10 by using the new multicast encryption key notification signal 12.
Upon receiving the new multicast encryption key notification signal 12, the encryption control frame inserting means 10 sends a multicast for notifying the ONT transmission device 4 in the multicast domain to which the new multicast encryption key is applied of the new multicast encryption key. The encryption key update notification frame is inserted into the downstream input signal 11 to generate the downstream signal 14.
The encryption circuit 9 encrypts the new multicast encryption key with the current unicast encryption key of each ONT transmission device 4 in the multicast domain whose key is to be updated, and transmits it as a PON downlink signal 16 to the ONT transmission device 4 (encryption). Multicast encryption key generation transmission step).
In the second embodiment, the “new multicast encryption key notification” transmitted from the OLT transmission apparatus 1 to the ONT transmission apparatus 4 in FIG. 6 is transmitted to a plurality of ONT transmission apparatuses in the control frame format shown in FIG. Broadcast by.
[0041]
In FIG. 8, “Default ONT-ID” (code value “0xFFFF”), which is an identification ID meaning a frame for all the ONT transmission devices 4, is stored in the ONT-ID of the preamble.
Also, a code value (0xFFFFFFFFFFFF) indicating a broadcast address is stored in DA, and an unused value different from the value used in the unicast encryption key exchange control frame (FIG. 5) is selected in Opcode. Stored code.
[0042]
In the Data area of FIG. 8, the ID of the ONT transmission device 4 in the multicast domain and the multicast encryption key encrypted with the unicast encryption key of the ONT transmission device 4 having the ID are, for example, “individual ONT-ID”. # 1 ”and“ new encryption key # 1 ”and stored in association with each other.
[0043]
Each of the ONT transmission devices 4 receiving the multicast encryption key notification of FIG. 8 extracts a new encryption key corresponding to the own device ID by the encryption / decryption circuit 106 and uses the current unicast encryption key of the own device. Decrypts the new multicast encryption key and transmits it to the encryption control frame extracting means 104 (multicast encryption key decryption step).
Subsequent operations are the same as in the first embodiment.
[0044]
As described above, the OLT transmission apparatus 1 broadcasts the new multicast encryption key notification to the plurality of ONT transmission apparatuses 4 and notifies the update of the new multicast encryption key. The above operation is periodically performed by the OLT transmission apparatus 1 and the respective ONT transmission apparatuses 4 to update the multicast encryption key.
Therefore, the OLT transmission apparatus 1 does not need to individually transmit a control frame to the plurality of ONT transmission apparatuses 4, so that the OLT transmission apparatus 1 does not press down the bandwidth and periodically updates the multicast encryption key. Even if a relatively simple encryption technique is applied, there is an effect that the concealment of multicast data in a broadcast (broadcast) communication architecture can be enhanced.
[0045]
Embodiment 3 FIG.
In the second embodiment, as shown in FIG. 8, an example in which the ID of the ONT transmission device 4 (ONT-ID) and the corresponding new encryption key are stored in the multicast encryption key notification. showed that.
In the third embodiment, another method for broadcasting a new multicast encryption key to a plurality of ONT transmission devices 4 will be described.
[0046]
The third embodiment differs from the second embodiment in the frame format of the multicast encryption key notification.
FIG. 9 shows a frame format of the multicast encryption key notification according to the third embodiment. In the Data area, a new multicast encryption key is encrypted with the unicast encryption key of each ONT transmission device 4 in the multicast domain. The stored "new encryption key" is stored, and the "HASH code value" generated from the new multicast encryption key using a predetermined hash function is stored.
Each “HASH code value” is the same value.
[0047]
The encryption circuit 9 of the OLT transmission apparatus 1 encrypts the new multicast encryption key with the current unicast encryption key of each ONT transmission apparatus 4 in the broadcast domain whose key is to be updated. At the same time, a HASH code value is generated from the new multicast encryption key by a predetermined hash function such as MD5 or SHA-1. The control frame format of FIG. 9 is broadcast from the OLT transmission apparatus 1 to the ONT transmission apparatus 4 (encryption / multicast encryption key generation / transmission step).
[0048]
Each of the ONT transmission devices 4 receiving the multicast encryption key notification of FIG. 9 extracts the new encryption key from the head by the encryption / decryption circuit 106 and decrypts the new encryption key with its own unicast encryption key.
At this stage, it is unknown whether or not the decrypted new encryption key has been encrypted with its own unicast encryption key, so the "temporary multicast encryption key" obtained by decrypting the new encryption key is obtained. ”, A“ temporary HASH value ”is generated using the same hash function as the OLT transmission apparatus 1.
If the “temporary HASH value” is compared with the “HASH code value” and they match, the “temporary multicast encryption key” is a valid new multicast encryption key notified from the OLT transmission apparatus 1. .
On the other hand, if the “temporary HASH value” and the “HASH code value” do not match, the new encryption key is not encrypted with the own device's unicast encryption key, The “temporary multicast encryption key” is not a valid new multicast encryption key notified from the OLT transmission apparatus 1. In this case, the next "new encryption key" is extracted from the DATA area, the new encryption key is decrypted again, the "temporary HASH value" is generated, and the "temporary HASH value" is compared with the "HASH code value". Until the "temporary HASH value" and the "HASH code value" match (multicast encryption key decryption step).
If there is no new encryption key that matches up to the end, the OLT transmission device 1 is notified of the fact, and requests retransmission or checks whether there is tampering on the route.
[0049]
The hash function is the “predetermined operation” in the present invention.
The "temporary multicast encryption key" is the "decryption multicast encryption key" in the present invention, the "HASH code value" is the "first constant" in the present invention, and the "temporary HASH value" is the "first hash value" in the present invention. 2 constant ".
[0050]
As described above, since the OLT transmission apparatus 1 does not need to individually transmit a control frame to the plurality of ONT transmission apparatuses 4, the bandwidth is not compressed.
In addition, by periodically updating the multicast encryption key by performing the above operation, even if a relatively simple encryption technology is applied, the concealment of the multicast data in the broadcast communication architecture is enhanced. There is an effect that can be.
[0051]
In FIG. 9, the HASH code value is stored in the Data area in association with each new encryption key, but the HASH code value may be stored in one place.
[0052]
In the above description, the ONT transmission device 4 extracts new encryption keys in order from the top of the data area of the multicast encryption key notification. However, the ONT transmission device 4 assigns an order to each ONT transmission device 4 and If the new encryption key to be stored is stored at the above-mentioned position in the Data area, a new multicast encryption key can be obtained at a high speed in the ONT transmission apparatus. It is possible to check for tampering.
Also, if the ID of each ONT transmission device and each new encryption key are stored in association with each other in this order, the acquisition of the new multicast encryption key in the ONT transmission device is speeded up. Also in this case, it is possible to check whether the new multicast encryption key has an error or has been tampered with.
[0053]
In the above description, an example in which a hash function is used has been described. However, the present invention is not limited to the hash function, and any other method may be used as long as the operation outputs a uniquely determined constant for input data.
[0054]
【The invention's effect】
As described above, by updating not only the unicast encryption key but also the multicast encryption key periodically, multicast (concealment of multicast data in communication architecture of type Sex can be strengthened.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a system configuration according to Embodiments 1 to 3 of the present invention.
FIG. 2 is a block diagram showing an OLT transmission apparatus according to the first to third embodiments of the present invention.
FIG. 3 is a block diagram showing an ONT transmission device according to the first to third embodiments of the present invention.
FIG. 4 is a unicast encryption key update sequence diagram according to the first to third embodiments of the present invention.
FIG. 5 is a frame format diagram of a unicast encryption key notification and a unicast encryption key update confirmation according to the first embodiment of the present invention.
FIG. 6 is a multicast encryption key update sequence diagram according to the first to third embodiments of the present invention.
FIG. 7 is a frame format diagram of a multicast encryption key notification according to the first embodiment of the present invention.
FIG. 8 is a frame format diagram of a multicast encryption key notification according to the second embodiment of the present invention.
FIG. 9 is a frame format diagram of multicast encryption key notification according to the third embodiment of the present invention.
[Explanation of symbols]
1 OLT transmission device
2 Optical coupler
3 Optical fiber
4 ONT transmission equipment
5 Encryption control frame extraction means
6 Unicast encryption key holding means
7 Multicast encryption key holding means
8 Multicast encryption key generation means
9 Cryptographic circuit
10 Encryption control frame insertion means
11 Downlink input signal
12 New multicast encryption key notification signal
13. Multicast key signal
14 Down signal
15. Multicast key signal
16 PON downstream signal
17 Encryption key signal for unicast
18 PON upstream signal
19 Unicast encryption key extraction signal
20 Up output signal
21 Unicast encryption key reception completion signal
22 Unicast encryption key search signal
23 Multicast key search signal
101 Encryption control frame insertion means
102 Unicast encryption key generation means
103 Multicast encryption key holding means
104 Cryptographic control frame extracting means
105 Encryption key holding means for unicast
106 encryption / decryption circuit
107 Up input signal
108 Unicast encryption key signal
109 Encryption key signal for unicast
110 PON upstream signal
111 PON downstream signal
112 Encryption key signal for unicast
113 Multicast encryption key signal
114 Decoded signal
115 Multicast key extraction signal
116 Downlink output signal
117 Unicast encryption key update completion notification signal.

Claims (13)

Connected to multiple subscriber units,
A multicast encryption key generating means for generating a multicast encryption key for encrypting a message to be multicast to the subscriber device;
Generating an encrypted multicast encryption key by encrypting the multicast encryption key with a unicast encryption key that is an encryption key unique to each of the subscriber-side devices; A station-side device having an encryption circuit for transmitting to the station-side device. The above encryption circuit,
Encrypting the multicast encryption key with the unicast encryption keys of the plurality of subscriber units, respectively, and generating a plurality of encrypted multicast encryption keys respectively corresponding to the subscriber units,
The station-side device according to claim 1, wherein the plurality of encrypted multicast encryption keys are transmitted to the plurality of subscriber-side devices. The above encryption circuit,
The plurality of encrypted multicast encryption keys are transmitted to the plurality of subscriber side devices in association with identifiers unique to the subscriber side devices corresponding to the respective encrypted multicast encryption keys. Item 3. An optical line terminal according to item 2. The above encryption circuit,
The plurality of encrypted multicast encryption keys,
3. The station-side device according to claim 2, wherein a constant uniquely determined by a predetermined operation from the multicast encryption key is transmitted to the plurality of subscriber-side devices. The station-side device according to any one of claims 1 to 4, wherein the multicast encryption key generation means generates a new multicast encryption key at a predetermined timing. A subscriber-side device that receives an encrypted message transmitted from the station-side device, the subscriber-side device forming a multicast domain for the station-side device together with other subscriber-side devices,
A unicast encryption key holding means for holding a unicast encryption key unique to the subscriber device used when the station device encrypts and unicasts a message to the subscriber device;
A unicast encryption key transmitting means for transmitting the unicast encryption key to the optical line terminal, and a multicast encryption key used for encrypting a message to be multicast by the optical line terminal in the multicast domain. An encryption / decryption circuit for receiving an encrypted multicast encryption key encrypted with the unicast encryption key transmitted from the cast encryption key transmission unit from the station side device, and decrypting the encrypted multicast encryption key with the unicast encryption key. A subscriber device. Has a unique identifier,
The encryption / decryption circuit,
The station-side device encrypts the multicast encryption key with the unicast encryption key of each of the subscriber-side devices in the multicast domain and associates the encrypted encryption key with the identifier of each of the subscriber-side devices. Receiving the transmitted plurality of encrypted multicast encryption keys,
An encryption multicast encryption key corresponding to the identifier of the subscriber side device is extracted from the received plurality of encrypted multicast encryption keys, and decrypted by the unicast encryption key of the own device. 8. The subscriber-side device according to 7. The encryption / decryption circuit,
A plurality of encrypted multicast encryption keys generated by the station device by encrypting the multicast encryption key with the respective unicast encryption keys of the subscriber devices in the multicast domain;
Receiving a first constant uniquely determined by a predetermined operation from the multicast encryption key from the station side device;
Decrypting the plurality of encrypted multicast encryption keys with the unicast encryption key of the subscriber side device to generate a decrypted multicast encryption key,
A second constant is generated from the generated decryption multicast encryption key by the above predetermined operation,
8. The subscriber-side apparatus according to claim 7, wherein when the first and second constants match, the decrypted multicast encryption key is determined to be the multicast encryption key. 8. The subscriber-side apparatus according to claim 7, wherein the unicast encryption key held by the unicast encryption key holding means is updated at a predetermined timing. A communication system comprising the station-side device according to claim 1 and the subscriber-side device according to claim 7. A method of notifying an encryption key from a station apparatus to a subscriber apparatus in a communication system including a station apparatus and a plurality of subscriber apparatuses connected to the station apparatus, comprising: A) a method for notifying an encryption key, comprising the steps of:
(1) The subscriber-side device transmits a unicast encryption key, which is an encryption key unique to the subscriber-side device used when the station-side device unicasts a message to the subscriber-side device, as described above. Transmitting a unicast encryption key to be transmitted to the optical line terminal;
(2) a multicast encryption key generating step in which the station apparatus generates a multicast encryption key that is an encryption key used when multicasting a message to the plurality of subscriber apparatuses;
(3) The station-side device encrypts the generated multicast encryption key with the unicast encryption key transmitted from the subscriber device to generate an encrypted multicast encryption key, and Generating and transmitting an encryption key for encrypted multicast to be transmitted to
(4) A multicast encryption key decryption step in which the subscriber device decrypts the transmitted encrypted multicast encryption key with the unicast encryption key of the subscriber device. In the encryption multicast key generation and transmission step,
The station-side device transmits the encrypted multicast encryption key in association with an identifier unique to each subscriber-side device,
In the multicast encryption key decryption step,
13. The subscriber unit according to claim 12, wherein the subscriber unit decrypts the encrypted multicast encryption key associated with the identifier of the subscriber unit using the unicast encryption key of the subscriber unit. Encryption notification method. In the encryption multicast key generation and transmission step,
The station-side device transmits the encrypted multicast encryption key and a first constant uniquely determined by a predetermined operation from the multicast encryption key,
In the multicast encryption key decryption step,
The subscriber unit decrypts the encrypted multicast encryption key with the unicast encryption key of the subscriber unit to generate a decrypted unicast encryption key,
A second constant is generated from the generated decryption multicast encryption key by the above predetermined operation,
13. The cipher notification method according to claim 12, wherein when the first constant and the second constant match, the decrypted multicast encryption key is determined to be the multicast encryption key.

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