JPH0345944B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an encrypted digital broadcast receiving device that can be used in a paid CATV (cable television system) or a paid satellite broadcasting system.

Conventional technology Some conventional paid broadcasting systems use a specific format that is not disclosed to the public, or use confidential data to prevent unauthorized viewing. Analog data privacy involves processing the baseband signal using a conversion means, and then using an inverse conversion circuit in the receiving equipment to restore the original signal. For example, there is a method of inverting the video synchronization signal from time to time.

Problems to be Solved by the Invention In such conventional techniques, there were problems such as the secret message algorithm being easily stolen, eavesdropping being relatively easy, and the signal deteriorating with the secret message.
Moreover, it has been difficult to realize a function of transmitting a specific signal from the transmitting side to remotely control the operation of individual receivers.

In view of this problem, the present invention performs highly secure polarization and encryption without signal deterioration in paid digital broadcasting, and transmits the functional operation of a specific channel or specific receiving device according to the contract details. An object of the present invention is to provide an encrypted digital broadcast receiving device for use in a system that can be remotely controlled from the side.

Means for Solving the Problems The encrypted digital broadcast receiving device of the present invention includes means for receiving data broadcast through a transmission path, and a first identification code mainly consisting of an individual identification code given to the receiving device in advance. a first identification code ROM to store; and a second identification code to store a second identification code paired with the first identification code.
a ROM, a match detection means for extracting data corresponding to a first identification code from the received data and comparing it with data in the first identification code ROM;
a second decryption means for decoding the received transmission key using data in a second identification code ROM to obtain a plurality of decryption keys and index numbers; and a plurality of decryption keys obtained by the second decryption means. storage means for storing the index number in association with an index number; decryption key selection means for extracting the index number of the encryption key used for encryption from the received data and selecting the decryption key of this index number;
The apparatus includes first decryption means for decrypting the received ciphertext using the decryption key selected by the decryption key selection means.

Effects According to the above configuration, the present invention is an encrypted digital broadcasting device that prepares a plurality of encryption keys with index numbers for use in encrypting plaintext, and identifies these data with a first identification code. The plain text is encrypted with the second identification code and then sent to each individual receiving device, and the plaintext is encrypted with an encryption key selected from a plurality of encryption keys, and the index number of this encryption key is sent along the transmission path. The first identification code is extracted from the data received through the transmission path, and the first identification code is compared with the data in the first identification code ROM that is individually given to the receiving device in advance. If the comparison results in a match, the received transmission key is decrypted using the data in the second identification code ROM to obtain a plurality of decryption keys and index numbers, and these are stored in the storage means. On the other hand, if the comparison results in a mismatch, the received transmission key data is discarded and not taken into the storage means, as the data is destined for another receiving device.

The index number of the encryption key used for encryption is extracted from the received data, and the index number is selected from the plurality of stored decryption keys by referring to the storage means using this index number. It decrypts with the decryption key and outputs plaintext. If the decryption key for the index number is not correctly stored in the storage means, the received ciphertext is illegally decrypted or is not decrypted, so that it operates to output something different from the plaintext.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. The figure shows a block diagram of an encrypted digital broadcasting device and an encrypted digital broadcasting receiving device according to an embodiment of the present invention.

In FIG. 1, 1 is a plaintext input terminal, 2 is an encryption key generation means, 20 is an encryption key selection means, 3 is a first identification code storage means, 4 is a second identification code storage means, and 5 is a second identification code storage means. Encryption means, 6 is a first encryption means, 7 is a data transmission means, and 8 is an encrypted digital broadcasting device that combines the above-described plaintext input terminal 1 to data transmission means 8 and encryption key selection means 20.

Further, 9 is a transmission cable, 11 is a data receiving means, 12 is a coincidence detection means, 13 is a first identification code ROM, 14 is a second identification code ROM, 15
16 is a second decryption means, 16 is a decryption key storage means, 2
1 is a decryption key selection means; 17 is a first decryption means;
Reference numeral 18 denotes a plaintext output end, and 19 denotes an encrypted digital broadcast receiving device that decrypts the data from the data receiving means 11 to the plaintext output end 18 and the decryption key selection means 21.

The operations of the encrypted digital broadcasting device and the encrypted digital broadcasting receiving device of this embodiment configured as described above will be described below in order from the outline of the system.

The encrypted digital broadcasting device 8 is connected to a plurality of encrypted digital broadcasting receiving devices via a transmission cable 9. Encrypted digital broadcast receiving device 1 shown in the figure
9 is one of them. An individual identification code is set in the encrypted digital broadcast receiving device 19 at the time of manufacturing and shipping the device. First identification code ROM13 and second identification code ROM14
corresponds to this. The identification code is created by the organization that manages the system. When a contract is signed between a device user or contractor and a system administrator, the new contract details are written to the data file and updated. The encrypted digital broadcasting device 8 stores the latest contract content data of all subscribers in the first identification code storage means 3 and the second identification code storage means 4 so that the data can be accessed. Plaintext input terminal 1
The program inputted into the program is encrypted by the first encryption means 6 and sent out and broadcast from the data sending means.

Instead of broadcasting the encryption key used by the first encryption means 6, the index number of the encryption key selected by the encryption key selection means 20 is broadcast from the data sending means 7 together with the program. A key table representing the correspondence between all index numbers and encryption keys is created by the encryption key generation means 2. The key table created by the encryption key generation means 2 is supplied to the encryption key selection means 20 and the second encryption means 5. The encryption key selection means 20 selects one index number from the key table and supplies this index number to the data transmission means 7, and also refers to the key table and selects the encryption key corresponding to the index number from therein. It selects and outputs it to the first encryption means 6. Using this encryption key, the first encryption means 6 encrypts the plaintext input from the plaintext input terminal 1 to create a ciphertext and supplies it to the data sending means 7. Note that the encryption key selection means 2
The index number and encryption key selected as 0 are changed every moment, about several times per second, using random numbers to prevent eavesdropping. Furthermore, the key table created by the encryption key generation means 2 is also updated, but the frequency is small.

In the encrypted digital broadcast receiving device 19, it is necessary to prepare a key table before broadcasting a program. The key table is delivered only to the equipment covered by the contract. Since it would be uneconomical to occupy a different route, carrier wave, or channel for this delivery than the program, the same channel as the program is time-division multiplexed and delivered. Furthermore, if the key table is known to a third party, there is a risk of illegal eavesdropping, so security must be ensured during delivery. Furthermore, in order to securely deliver a different key table depending on the contract for each device only to the target device, different encryption is performed for each individual device. below,
This encryption will be explained.

The identification code for each encrypted digital broadcast receiving device is set to include a first identification code for identifying the device and a second identification code used as an encryption key. Note that the second identification code is uniquely determined by the system administrator in association with the first identification code, but is created in such a way that the first identification code is not necessarily determined from the second identification code. . The first identification code and the second identification code are stored in the first identification code storage means 3 and the second identification code storage means 4, respectively, as data of all subscribers.

Encryption of the key table for each individual device for safe delivery is performed in the second encryption means 5 using the second identification code retrieved from the second identification code storage means 4 as the encryption key. The table created in this way is called a transmission key table. Therefore,
Even if the key table is the same, if the second identification code is different, the transmission key table encrypted by this will be different for each device. The transmission key table is created sequentially for all contracted devices. Using these data, the key table is delivered to one contracted device by packing the first identification code and the transmission key table and sending it out from the data sending means 7 along with other data. When the delivery of the key table to one contracted device is completed, the delivery is performed serially to the next contracted device, and so on, and the key table is distributed to all the contracted devices. Deliveries are repeated taking into account transmission errors and receiving equipment that is not powered on.

The cipher text, index number, first identification code, and transmission key table described above are input to the data sending means 7 in relation to each other in chronological order or in data format. The data sending means 7 converts these data into a format suitable for modulation, and outputs the data to the transmission cable 9 on an SPK-modulated carrier wave in the VHF band. Depending on the scale of the system, the transmission cable 9 is connected to the end user's encrypted digital broadcast receiving device through linking, relaying, and distribution. The encrypted digital broadcast receiving device 19 is one of them.

The operation of an embodiment of the encrypted digital broadcast receiving apparatus of the present invention in a broadcasting system configured with the above system will be described.

In the encrypted digital broadcast receiving device 19, the data receiving means 11 receives multiplexed data through the transmission cable 9. The received multiplexed data is outputted from the data receiving means 11 according to its contents. A first identification code extracted from multiplexed data and a first identification code individually assigned to the receiving device in advance.
The data in the ROM 13 is compared with the data in the ROM 13 by the matching detection means 12. If the comparison results match, the transmission key table extracted from the data received by the data receiving means 11 is transferred to the second identification code ROM 14.
The data is decrypted by the second decryption means 15 using the data as a decryption key, and the decrypted key table is stored in the decryption key storage means 16. In this way, the reception of the delivered key table is completed. The stored decrypted key table is supplied to the decryption key selection means 21.

The first identification code extracted from the multiplexed data and the data in the first identification code ROM 13 are
As a result of the comparison by the match detection means 12, if there is a mismatch, the data in the received key table is discarded as the pack data is data for another receiving device, and the data is not stored in the decryption key storage means 16. prohibit. In this case, the reception of the key table is complete, but since the key table is delivered repeatedly in sequence, the device waits for its own first identification code to be sent next.

On the other hand, the index number of the encryption key extracted from the received multiplexed data is supplied to the decryption key selection means 21, and by referring to the decrypted key table input from the decryption key storage means 16, the index number is decrypted from the table. A key is selected and output to the first decryption means 17.

Further, the ciphertext extracted from the received multiplexed data is supplied to the first decryption means 17, and is decrypted by the first decryption means 17 using the decryption key inputted from the decryption key selection means 21. It operates to output to the plain text output terminal 18. In this way,
The decryption of the receiving device with which the contract has been made is carried out, the program is correctly decrypted, and the service is provided.

If the reception of the key table to be delivered has not yet been completed, it waits for its first identification code to be sent, and then, when the reception of the key table is completed,
Regular service is performed through the above-described operations. Even at the time of broadcasting the program, if the received key table has not yet been received, the decryption key corresponding to the index number is unknown even if the index number is received. Since the encrypted text is illegally decrypted or not decrypted at all, the output of the output terminal 18 is different from the plain text, and the program operates in such a way that the user cannot receive the program service. In such cases, mute the output.

Therefore, there are various cases in which program services cannot be received, such as the following.

(a) In the case of non-contracted equipment, the first identification code of the receiving equipment will not be broadcast, so it will not work.

(b) If it is a contracted device and the program or channel is not subscribed to, the part of the key table used for the program has not been delivered, so it will not work only for that program or channel.

(c) If the contract period has expired and the contract has not been renewed, the broadcasting of the first identification code will be stopped or incorrect data will be delivered to the key table, causing the receiving device to stop operating.

Although different from the embodiment of the present invention, the operation in the case of a spying device will be described.

(d) In the case of unauthorized eavesdropping equipment, it is impossible to steal the key table from the broadcast data (transmission key table), so eavesdropping cannot be performed.

(E) If the key table is obtained illegally using an unauthorized eavesdropping device, the key table will be updated after a predetermined period of time, and the eavesdropping operation will stop after that.

(f) If the first identification code ROM and the second identification code ROM are illegally copied from a legitimate contracted device in an illegal eavesdropping device, the eavesdropping device becomes a clone of the contracted device; If you perform maintenance such as replacing the second identification code ROM during periodic inspections, the eavesdropping operation will stop from then on.

Note that in the above embodiment, the first identification code
Although the ROM and the second identification code ROM are described as independent configuration means, it goes without saying that they may be integrated into an equivalent identification code ROM.

Effects of the Invention As is clear from the above description, the present invention shares an identification code with an encrypted digital broadcasting device and an encrypted digital broadcasting receiving device, identifies the receiving device with the first identification code, and remotely controls the receiving device individually. However, since the second identification code is configured to encrypt and decrypt information such as the key table required to decrypt individual contracted programs, specific contracted devices can be individually controlled by remote control on the transmitting side. Can be safely decrypted. For example, it is possible to realize an excellent encrypted digital broadcast receiving apparatus that can be used for CATV pay digital broadcasting, satellite pay broadcasting, and pay broadcasting that utilizes vacant terrestrial channels.

In particular, since the encryption key can be switched randomly and frequently, even if temporary data is illegally decrypted by eavesdropping on the transmitted text, it is almost impossible to continue decrypting the data. It produces the effect of extremely high ability.

In addition, the key table required for decrypting legitimate contracted equipment is encrypted with a second identification code that differs for each individual equipment, and is then delivered as a transmission key table, so the transmission key table is different for each individual equipment. Become something. Therefore, even if this is stolen, the second identification code is unknown because it is not transmitted, and it is almost impossible to decipher it. That is, it is possible to deliver the key table to each individual encrypted digital broadcast receiver, and moreover, the effect is that the key table can be delivered and received extremely safely.

Note that since the encryption is performed digitally, it goes without saying that there is no deterioration in the characteristics of the decrypted signal.

[Brief explanation of drawings]

The drawing is a block diagram of an encrypted digital broadcasting device and an encrypted digital broadcasting receiving device according to an embodiment of the present invention. 1... Plaintext input terminal, 2... Encryption key generation means, 3
...First identification code storage means, 4...Second identification code storage means, 5...Second encryption means, 6
...first encryption means, 7...data transmission means,
8... Encrypted digital broadcasting device, 9... Transmission cable, 11... Data receiving means, 12... Match detection means, 13... First identification code ROM, 14...
... second identification code ROM, 15 ... second decryption means, 16 ... decryption key storage means, 21 ... decryption key selection means, 17 ... first decryption means, 18 ...
... Plaintext output end, 19... Encrypted digital broadcast receiving device, 20... Encryption key selection means.

Claims (1)

[Claims] 1 means for receiving data broadcast through a transmission path;
a second identification code ROM that stores a second identification code paired with the first identification code; a second identification code ROM that extracts data corresponding to the first identification code from the received data; 1st
a match detection means that compares the received transmission key with the data in the second identification code ROM;
a second decryption unit decrypting data using ROM data to obtain a plurality of decryption keys and index numbers; a decryption key storage means for storing a plurality of decryption keys associated with an index number; and extracting an index number of an encryption key used for encryption from the received data and extracting a decryption key corresponding to this index number from the decryption key storage means. An encrypted digital broadcast receiving device comprising: a decryption key selection means; and a first decryption means for decrypting a received encrypted text using the decryption key selected by the decryption key selection means.