JPH03179841A - Cryptographic digital broadcast receiver - Google Patents

Abstract

PURPOSE:To deliver individual information individually and safely with remote control at sender side by specifying a receiver with an identification code and ciphering and decoding information such as a key table required to decode an individual contract program while applying remote control individually. CONSTITUTION:A 2nd decoding means 15 receiving a data broadcast through a transmission line 9, extracting a data corresponding to an identification code and collating the data with a data of an identification code ROM 13 and decoding a decoding key or a decoding key group revising the received data at a low speed is provided. Moreover, a decoding key reproducing means 21 extracting a 1st key or a key group revised at a high speed from the received data and reproducing a substantial decoding key from the key and the decoding key or decoding key group and a 1st decoding means 17 or the like decoding the received cryptographic sentence under the substantial decoding key are provided. Thus, the privacy call processing and ciphering with high safety without signal deterioration are applied and the operation of specific channel and specific receivers is controlled remotely from the sender side in response to the content of contract.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to an encrypted digital μ broadcast receiving apparatus that can be used in a paid CATV (cable television system) or a paid satellite broadcasting system.

BACKGROUND OF THE INVENTION Conventional paid broadcasting systems include those that use a specific format that is not disclosed to the public, and those that use privacy 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 technology, the algorithm for secret stories is easily stolen, and eavesdropping is relatively easy. However, there are problems such as signal deterioration due to confidential information. Furthermore, 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 provides highly secure polarization and encryption for paid digital broadcasting without signal deterioration, and allows the functional operation of specific channels and specific receiving equipment according to the contract details. An object of the present invention is to provide an encrypted digital broadcast receiving device that can be used in a system that can be remotely controlled from the transmitting side.

Means for Solving the Problems In order to solve the above conventional problems, the encrypted digital broadcast receiving device of the present invention includes means for receiving data broadcast through a transmission path, and an individual identification code given in advance to the receiving device. an identification code ROM to be stored; a match detection means for extracting data corresponding to the identification code from the receiving data and comparing it with data in the identification code ROM; and a second key or key group that is updated at a low speed from the received data. a second decryption means for decoding the data using the data in the identification code ROM to obtain a decryption key or a decryption key group; and storing the decryption key group or decryption key group obtained by the second decryption means. a storage means, a decryption key reproducing means for extracting a first key or a group of keys to be updated at high speed from received data and regenerating an actual decryption key from this and the decryption key or the decryption key group; and the decryption key reproducing means. The first decryption means decrypts the received cipher text under the actual decryption key output from the decryption key.

Effect The present invention is an encrypted digital broadcasting device with the above configuration, and
A slowly updated encryption key or a group of encryption keys used for plaintext encryption is individually encrypted with an identification code and then sent to a receiving device specified by an identification code,
When receiving, through a transmission path, a broadcast signal in which a cryptographic key or cryptographic key group that is updated normally or at high speed is encrypted with a second cryptographic key that is updated slowly, the encrypted digital broadcast receiving device of the present invention The identification code is extracted from the data received through the transmission path, and compared with the data in the identification code ROM that has been individually assigned to the receiving device in advance.

If the codes match as a result of the verification, the second decryption means decrypts the received low-speed transmission key or transmission key group using the data in the identification code ROM. The decryption key or decryption key group output from the second decryption means is stored in the decryption key 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.

A first key block or key group that is updated at high speed is extracted from the received data, decrypted with data in the decryption key storage means, and output as an actual decryption key. It decrypts the received ciphertext using the actual decryption key and outputs the plaintext.

If the decryption key or the decryption key group is not correctly stored in the decryption key storage means, the received ciphertext is illegally decrypted or not decrypted, so that it operates to output something different from the plaintext.

EXAMPLE Hereinafter, an example of the present invention will be described 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 the figure, 1 is a plaintext input terminal, 2 is an encryption key generation means, 2
o is an encryption key selection means, 3 is a first identification code storage means,
4 is the second identification code storage means, 5 is the second encryption means, 6 is the first encryption means, 7 is the data transmission means, and 8 is the data transmission means 81 from the plain text end 1 to the data transmission means 81 and encoded. This is an encrypted digital broadcasting device in which a key selection means 20 is combined.

Further, 9 is a transmission cable, 11 is a data receiving means, 12
13 is a first identification code ROM; 14 is a match detection means; 13 is a first identification code ROM;
is a second identification code ROM, 16 is a second decoding means,
16 is a decryption key storage means, 21 is a decryption key selection means, 17 is a first decryption means, 18 is a half output terminal, and 19 is a section from the data receiving means 11 to the plaintext output terminal 18 and the decryption key. This is an encrypted digital broadcast receiving device with a combination of 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. The encrypted digital broadcast receiving device 19 shown in the figure 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 RO
M14 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. The program input to the plain text input terminal 1 is encrypted by the first encryption means 6 and sent out and broadcast from the data sending means 7.

The encryption key used by the first encryption means 6 is not broadcast, but the index number of the encryption key selected by the encryption key selection means 20 is broadcast from the data transmission means 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 transmitted to the encryption key selection means 20 and the second encryption means 6.
supply to. 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 is output 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. Incidentally, the index number button and the encryption key selected by the encryption key selection means 20 are updated every moment about several times per second using random numbers in order to prevent eavesdropping. Furthermore, the key table created by the encryption key generation means 2 is also updated at a low speed.

In the encrypted digital broadcast receiving apparatus 19, it is necessary to prepare and write a key table before broadcasting a program.

The key table is delivered only to the equipment covered by the contract. Since it is uneconomical to occupy a different route, carrier wave, and channel/I/ for this distribution, the same channel as the program is time-division multiplexed and distributed. If the shredded key table becomes known to a third party, there is a risk of illegal eavesdropping, so security must be ensured during delivery. Moreover, each device has a different key table depending on the contract.
In order to securely deliver data only to the target device, different encryption is applied to each individual device. This encryption will be explained below.

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. In addition,
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 using the second identification code extracted from the second identification code storage means 4.
The second encryption means 6 uses the identification code as the encryption key. The table created in this way is called a transmission key table. Therefore, even if the key tables are the same, if the second identification codes are different, the encrypted transmission key tables will be different for each individual device. The transmission key table is created sequentially for all contracted devices.

Using these data, the key table is delivered to one contracted device using the first identification code and the transmission key tape/L.
/ is packed together with other data data sending means 7
This is done by sending it from . Once the key table has been delivered to one contracted device for LT, the delivery is performed serially to the next contracted device, and so on, and the key table is delivered to all contracted devices without exception. Since updating of the second key or key group is slow, it is not updated at least during the period 1 when delivery to all contracted devices is completed. Deliveries are repeated taking into account transmission errors and receiving equipment that is not powered on.

The ciphertext, index number, first identification code, and transmission key table described above are inputted to the data sending means 7 in relation to each other in chronological order or in a data format. The data sending means 7 converts these data into a format suitable for modulation, carries them on a PSK-modulated VHF band carrier wave, and outputs them to the transmission cape/L/9. Depending on the scale of the system, the transmission cape 1v9 is connected to the end user's encrypted digital broadcast receiving device through links and relays. 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 transmission cape /l/
9, the data receiving means 11 receives the multiplexed data. The received multiplexed data is output from the data receiving means 11 according to its contents. The first identification code extracted from the multiplexed data and the data in the first identification code ROM 1a individually assigned to the receiving device in advance are compared by the coincidence detection means 12. If the matching result matches,
The transmission key table extracted from the data received by the data receiving means 11 is decoded by the second decrypting means 16 using the data in the second identification code ROM 14 as a decrypting key, and the decrypted key table is stored in the decrypting key storage means 16. Store. 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 matched by the coincidence detection means 12.
As a result of the comparison, if there is a mismatch, the received data in the key table is discarded and storage in the decryption key storage means 16 is prohibited, assuming that the pack data is data for another receiving device.

In this case, reception of the key table is incomplete, 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 the decryption key storage means 1
6), the decryption key of the index number, that is, the actual decryption key, is selected and output to the first decryption means 17.

In addition, the ciphertext extracted from the received multiplexed data is
The first decryption means 17 uses the real decryption key inputted from the decryption key selection means 21.
It decrypts the data and outputs the plaintext to the plaintext output terminal 18. In this way, the decryption of the receiving device with which the contract is valid is performed, the program is correctly decrypted, and the service is provided.

If the reception of the delivered key table is incomplete, it waits for its own first identification code to be sent, and when the reception of the backup table is completed, the regular service is performed by the above-mentioned operation. .

Even at the time of broadcasting the program, if the delivered key table has not yet been received, even if the index number has been received, the corresponding decryption key is unknown, so the first decryption means 1
At step 7, the received encrypted text is decrypted illegally or not decrypted at all, so that the output terminal 18 outputs something different from the plain text, and operates in such a way that the program service cannot be received. In such cases, mute the output.

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

(7) In the case of an uncontracted device, the first identification code of the receiving device is not broadcast, so the device does not operate.

(b) If the device 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 operate only for that program or channel.

(1) If the contract period has expired and the contract has not been renewed, the broadcasting of the first identification code is stopped or incorrect data is delivered to the key tape p, so that the receiving device stops operating.

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

(b) 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.

(b) If the key table is illegally obtained 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.

(Kari) 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,
After that, the eavesdropping operation will stop.

In addition, in the above embodiment, the first identification code ROM and the second
Although the identification code ROM is an independent configuration means, it is not the case that the identification code ROM may be integrated into an equivalent identification code ROM.

Further, it is clear from the drawings and the above description that the key table may have one key, and in this case, the data corresponding to the index number may be used for further encryption/decryption. That is, although the key table described in the embodiment is equivalent to a hoe or a group of keys, effects of the invention As is clear from the above explanation, the present invention provides an identification code for an encrypted digital broadcasting device button and an encrypted digital broadcasting receiving device. While identifying the receiving device using its identification code and remotely controlling it individually, it is possible to encrypt and decrypt information such as the key table (second key or key group) required to decrypt each contracted program. Since the system is configured so that the information can be transmitted individually and safely to specific contracted devices under remote control on the sending side.

In addition, since the encryption key can be switched randomly and frequently, even if the transmitted text is illegally decrypted by eavesdropping on a temporary pig, it is almost impossible to continue decrypting it. The effect is that his ability to tell secrets is extremely high.

In addition, the key table required for decrypting legitimate contracted equipment is encrypted with a different identification code for each individual equipment and delivered as a transmission key table, so the transmission key table will be different for each individual equipment. .

Therefore, even if someone steals someone else's transmission key table, it is almost impossible to decrypt it. In this way, it is possible to deliver the key table to each individual encrypted digital broadcast receiving device, and there is an effect that the key table can be delivered and received extremely safely.

However, since the encryption is performed digitally, there is no guarantee that there will be no deterioration in the characteristics of the decrypted signal.

As described above, the present invention can realize a fully encrypted digital broadcast receiving apparatus that can be used for, for example, CATV pay digital broadcasting, satellite pay broadcasting, and pay broadcasting that utilizes vacant terrestrial channels.

[Brief explanation of drawings]

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

Claims (1)

[Claims] Means for individually encrypting and delivering a second key or key group that is updated slowly with an identification code unique to a receiving device; An encrypted digital broadcasting device comprising means for encrypting plaintext using the second key or group of keys and broadcasting the same to a plurality of receiving devices in common, and means for encrypting and broadcasting plaintext using the first key or group of keys. A receiving device for receiving a broadcast signal, comprising: means for receiving data broadcasted through a transmission path; an identification code ROM for storing an individual identification code given to the receiving device in advance; a match detection means for extracting corresponding data and comparing it with the data in the identification code ROM, and a second key or key group that is updated at a low speed from the received data, using the data in the identification code ROM to decrypt a second key or a group of keys to obtain a decryption key or a decryption key. a second decryption means for obtaining a decryption key group; a storage means for storing the decryption key or decryption key group obtained by the second decryption means; and a first key or key group that is updated at high speed from received data. a decryption key regeneration means for extracting the decryption key and regenerating the actual decryption key from the decryption key or the decryption key group; and decrypting the received ciphertext under the actual decryption key output from the decryption key regeneration means. An encrypted digital broadcast receiving device comprising a first decryption means.