JPS6190547A - Ciphered digital transmitter - Google Patents

Abstract

PURPOSE:To decode individually ciphering for a receiver by providing two kins of identification codes to a transmission and reception side device, using one code to apply individual control of the receiver and using the other code to cipher and decode a transmission key thereby applying sophisticated ciphering and applying the control of the transmission side. CONSTITUTION:Broadcast data is converted into a ciphering sentence at a ciphering means 6 at the transmission side 8 by using one of plural ciphering keys of a ciphering key generating means 2. On the other hand, all ciphering keys of the means 2 are ciphered by a ciphering means 5 by using data of an identification code storage means 4. The said ciphering sentence a transmission key, an address code of an output receiver of an identification code storage means 3, and data specifying concretely the key used in a ciphering key selection means 20 are inputted to a data transmission means 7 while they are related mutually on a data format or in time series. A receiver 19 divides the specific identification code, which is stored in identification code ROMs 13 and 14. When the data of the ROM13 and the received address code are coincident, the received transmission key is decoded under the data of the ROM14.

Description

[Detailed description of the invention] Industrial field of application The present invention is applicable to paid C, ATV systems (cable television systems).
This relates to an encrypted digital broadcasting device that can be used for satellite broadcasting systems and paid satellite broadcasting systems.

Conventional configuration and its problems Conventionally, in paid broadcasting, the signal is converted and sent for confidential information, and only devices that are allowed to receive it are configured to reverse convert the signal and obtain the original signal. It has been known. Since conventional paid broadcasting was mainly based on analog transmission, it was difficult to achieve a high degree of privacy, which was not only economically disadvantageous, but also had the disadvantage of signal deterioration due to privacy. In addition, there is a problem in that it is completely impossible to divide the secret message by 1'/4 on each receiver's device individually and under the control of the transmitter.

Furthermore, there was a drawback that it was easy for the equipment to be illegally modified and eavesdropped on.

Purpose of the Invention The present invention provides an excellent encryption technique that performs advanced encryption without signal deterioration in paid digital broadcasting, and that allows the receivers of specific subscribers to individually decrypt the encryption under the control of the transmitter. The purpose is to provide broadcasting equipment.

Another purpose is to create an encrypted digital transmission device that enables new pay channel services by transmitting this contract data from the transmitting side based on the channel contract and limiting the operation of the receiver so that it can only receive the contracted channel. It is to provide.

Composition of the Invention The encrypted digital broadcasting device of the present invention includes an encryption key generation means, a first encryption means for converting plaintext into ciphertext under an encryption key generated by the encryption key generation means, and a first encryption means that allows decryption. or a first identification code storage means and a second identification code storage means of a plurality of receiving devices, a means for encrypting an encryption key under the second identification code, and at least a ciphertext and a first identification code; A digital data transmitting device comprising a code and a means for transmitting an encrypted encryption key, a means for receiving an i' signal broadcast through a transmission path, and a first identification code flOM for recording an identification code of a receiving device. and the second
an identification code ROM, a means for detecting coincidence between the data in the identification code ROM and the received first identification code, and a second identification code ROM for decrypting the received encryption key data under the data in the second identification code ROM. a digital data receiving device comprising a decryption means and a first means for decrypting the ciphertext received under the output data of the second decryption means;
In the digital data sending device, a plurality of encryption keys are generated, key numbers are assigned to them, one of them is used for encryption, and a non-number used is assigned before transmission. At the same time, the entire encryption key data is also transmitted in a manner in which the key number is associated with the transmitted data encrypted with the second identification code, and the digital data receiving device decrypts the entire transmission R and divides it into key numbers. It is configured to store the ciphertext in the storage means, detect the key number of the ciphertext, and supply the corresponding decryption key to the second decryption means. This makes it extremely difficult for the sender to eavesdrop on the signal, and allows the sender to control the decryption of a particular receiver. In addition, the transmitter has a contract channel data file and contract channel data selection means for selecting and transmitting contract channel data based on a reception contract using an encryption key number, and the transmitting device has a contract channel data file and contract channel data selection means for selecting and transmitting contract channel data based on a reception contract, and the digital data receiving device can check whether the channel is contracted or not. The configuration is such that the reception operation can be limited by the following.

DESCRIPTION OF EMBODIMENTS 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 according to an embodiment of the present invention. In the figure, 1 is a plaintext input terminal, 2 is an encryption key generation means, 3 is a first identification code storage means, 4 is a second identification code storage means, 6 is a second encryption means, and 6 is a first encryption 22 is a contract channel data file; 23 is a contract channel data selection means;
Reference numeral 7 denotes a data sending means, and 8 a digital data sending device in which the above-described plaintext input terminal 1 to data sending means 7 are combined.

9 is a transmission cable, 11 is a data receiving means, 12 is a coincidence detection means, 13 is a first identification code 10M, 14 is a second identification code ROM, 15 is a second decryption means, 16 is a decryption key storage means, 17 21 is a first decryption means, 21 is a decryption key selection means, and 24 is a digital data receiving device in which the contracted data receiving means 11 to the plain text output terminal 18 are decrypted.

The operation of the encrypted digital broadcasting apparatus of this embodiment configured as described above will be described below.

First, the digital data sending device 8 is linked to a plurality of digital data receiving devices 19 via a transmission cable 9. The digital receiving device 19 shown in FIG. 1 is one of them. On the transmitting side, the identification code of each receiving device based on a paid reception contract is managed as data. This identification code is further divided into two parts and each is stored in the first identification code storage means 4. Plaintext digital data, which is the content of the broadcast, is input to the first encryption means 6 through the plaintext input terminal 1. In the first encryption means 6, plaintext digital data is converted into ciphertext under the encryption key obtained by the encryption key selection means 20 which selects one of the plurality of encryption keys generated by the encryption key generation means 2. On the other hand, all the encryption keys of the encryption key generation means 2 are further encrypted by the second encryption means 6 under the data of the second identification code storage means 4 described above. That is, the encryption key data is converted into a plurality of encrypted encryption key data. This is called a transmission key for simplicity. The ciphertext explained above,
) The transmission key, the output data of the first identification code storage means 3, and the data for specifically identifying the key used by the encryption key selection means 2o are correlated with each other in time series or data format. Sending means 7
Enter. At the same time, the contract channel data selection means 23 extracts data from the contract channel data file 22 that corresponds to code number 1, and inputs it to the data sending means 1 in addition to the data format. The data sending means 7 converts the aforementioned input data into a format suitable for modulation, and outputs it to the transmission cable 9 on a PSK-modulated VHF band carrier wave.

The transmission cable 9 performs relaying and distribution according to the scale and is connected to the digital data receiving device 19 of each consumer. Digital data receiving device 19 is one of them.

Next, the operation of the digital data receiving device 19 will be explained. The signal from the transmission cable 9 is demodulated into received data by the data receiving means 11. The received data is a data in a transmission format, and its contents include a ciphertext, a transmission key, a first identification code, and contract channel data. The identification code unique to the receiving device 19 is divided into two parts and stored in the first identification code RoM13 and the second identification code ROM14, respectively. 1st identification code ROM1
3 and the received data of the 16th identification code are matched or mismatched by the matching detection means 12. If they match, the received transmission key is further decrypted by the second decryption means 15 under the data of the second identification code R'0M14. This decrypted transmission key is a decryption key for decrypting the ciphertext into plaintext. This decryption key is stored and held in the decryption key storage means 16 only when the aforementioned first identification code matches. The received data includes data for selecting and specifying one encryption key from among a plurality of encryption keys, and which data is extracted from the received signal and sent to the decryption key selection means 21. input. The decryption key selection means 21 selects one of the composite keys held in the decryption key storage means 16 based on the data for selection described above, and selects one from the composite keys held in the decryption key storage means 16 and sends it to the first decryption means 1.
Output to 7.

The first decryption means 17 decrypts the received ciphertext into plaintext using the selected decryption key, and outputs the plaintext to the plaintext output terminal 18.

If the first identification code is different from the received one, that is, if the result of the matching detection means 12 is a mismatch, the writing operation of the decryption key storage means 16 is prohibited to prevent an incorrect identification code from being stored. I have to. Since the transmission key is sent repeatedly, if the identification codes match and the record is kept only when there is no transmission error, decryption can always be performed correctly.

At the same time, the contract channel data is stored in the contract channel data storage means 24 when the first identification codes of the respective receivers match and there is no error. A signal indicating whether or not the encryption key number data described above has been purchased is obtained. This contract status signal is input to the first decoding means 17 to control the function of decoding the encrypted text into plain text, and makes it work if the contract is signed, and disables it if the contract is not signed. In order to prevent undecrypted data from being output to the plain text output terminal 18, nothing is output when there is no contract.

The above is an explanation of the basic operations of the digital data transmitting device 8 and the digital data receiving device 19.

Next, specific operational operations will be explained.

Each receiving device 19 always has a first identification code,
These are codes unique to that device.

It has a so-called address code. The fee system is collected based on a contract between each consumer and the broadcasting supply side, and the contract is usually for one month. On the broadcasting supply side, the correct transmission key is sent only to the contracted channels of each consumer, thereby preventing non-contractors from receiving or receiving channels to which they do not have a contract. These operations can be controlled arbitrarily by the broadcasting provider. Moreover, the encryption key is not fixed, and multiple encryption keys can be arbitrarily selected and specified. This has the effect of making it impossible to decipher and eavesdrop on the transmitted data. In other words, since the encryption key changes from moment to moment, there is no point in decoding temporary data.

In addition, the cipher text in the transmitted data is transmitted to all receiving devices 9.
However, since the transmission key is encrypted using the second identification code, it is different for each receiving device 19. Therefore, it is difficult to steal the transmission key, and even if the transmission key is stolen, the correct decryption key cannot be reproduced unless the second identification code of the receiving device 19 is known. As is clear from the above explanation, the second identification code is semi-fixed in accordance with the contract for both sending and receiving devices, and is not transmitted, so it is almost impossible for anyone else to know the second identification code. It is.

Next, the operation of encryption key numbers will be explained.

As described above, transmission keys and contract channel data are different for an unspecified number of customers. Therefore, it is necessary to deliver these data to all consumers, so they are sent serially one after another, and these data are delivered over a relatively long period of time. As mentioned above, when the contract period changes, these data should also be updated, but if these new data are received after the transition, there will be a blank space due to the transition, which is inconvenient. In order to avoid such inconvenience, in this embodiment, the transmission key and contract channel data are divided into those for the current contract period and the next contract period, and each is assigned an encryption key number and distributed. Both of these data are stored in the decryption key storage means 16 and the contract channel data storage means 24, and as the contract period changes, new data can be obtained from the data for selection. In this embodiment, the data of the encryption key number is 1 bit, and is changed alternately from 0 to 1 or from 1 to 0 at the transition of the contract period. Of course, this encryption key number data is common to all customers and can be received at the same time, so there will be no gaps when the contract period is transferred, and the transfer will be completed almost instantly. It is.

In the above embodiment, the transmission path is a cable, but it is not limited to cables, and any cable can be used as long as it has the function of transmitting signals.

For example, it may be an optical transmission network, an ATV cable network, or a satellite broadcasting network.

Effects of the Invention As is clear from the above explanation, the present invention has advantages in the following aspects: Since both the A-side device and the receiving-side device have an identification code of 2FFLA, and one side controls the receiving device individually, the other side performs encryption/decryption of the transmission key, so the sending side By controlling the receivers of specific subscribers, it is possible to individually and safely decrypt the receivers, and the effect is that it is possible to realize an excellent encrypted digital broadcasting device that can be used for, for example, paid digital zero ATV broadcasting or paid satellite broadcasting. It is something that can be done. In particular, since a plurality of encryption keys are used and these keys are cut every moment, even if the transmitted data is decrypted, it is impossible to decrypt the data continuously, resulting in a very high level of security against eavesdropping.

Furthermore, when the device according to the present invention is used in a paid transmission system, only contracted channels can be received and deciphered, making it almost impossible to eavesdrop on non-contracted channels by unauthorized modification. . Furthermore, it is possible to provide a device that can continuously receive data according to the contract without causing data blank time when the contract period changes. □ Furthermore, since the present invention is based on the broadcasting of digital signals, there is essentially no problem such as deterioration of speech due to polarization in analog transmission, which was mentioned previously as a conventional example, and there is no signal deterioration due to encryption. Needless to say.

[Brief explanation of drawings]

The drawing is a block diagram of an encrypted digital broadcasting device according to an embodiment of the present invention.

Claims (1)

[Claims] An encryption key generation means, a first encryption means for converting plaintext into ciphertext under an encryption key generated by the encryption key generation means, and a first identification code storage means of one or more receiving devices that allows decryption. and a second identification code storage means, a means for encrypting the encryption key under the second identification code, and a means for transmitting at least the ciphertext, the first identification code, and the encrypted encryption key. A digital data transmission device equipped with
means for receiving data broadcast through a transmission path; and a first identification code ROM for recording an identification code of the receiving device.
and a second identification code ROM, a means for detecting a match between the data in the identification code ROM and the received first identification code, and decrypting the received encryption key data under the data in the second identification code ROM. a digital data receiving device comprising a second decrypting device and a first decrypting device that decrypts the received cipher text under the output data of the second decrypting device, and the digital data transmitting device In addition to generating multiple encryption keys and assigning key numbers to them, one of them is used to encrypt and send the key number to be used.At the same time, data of all encryption keys is transmitted. The transmission key encrypted with the second identification code is also associated with a key number and transmitted, and the digital data receiving device decrypts all the transmission keys, divides them into key numbers and stores them in the storage means, and also stores the ciphertext in the storage means. the digital data transmitting device is configured to detect a key number and supply a corresponding decryption key to a second decryption means, and the digital data transmitting device further includes a contract channel data file for each of the digital data receptions;
The contract channel data selection means selects the contract channel data depending on the key number, and the contract channel data output from the contract channel data selection means is sent out from the data sending means, and the digital data The receiving device includes means for storing contract channel data in the received data when the received data matches the first identification code, and detecting the key number from the received data to determine the contract channel data corresponding to the key number. 1. An encrypted digital transmission device, comprising: means for stopping decryption or plaintext output of a receiving device depending on the selected contract channel data.