JPS60134643A - Control information transmission system - Google Patents

Abstract

PURPOSE:To attain prevention of interception with an inexpensive receiver by ciphering the 2nd key signal controlling the change of a code series of the 1st key signal by means of the 3rd key signal, transmitting the result through a broadcast line, using the 4th key signal at each subscriber receiver so as to apply conversion inverse to that at the transmission side and reproducing a broadcast program signal. CONSTITUTION:The signal form of an original signal, i.e., a broadcast program signal 1 is changed by a scrambler 2, the signal is cnverted into a scrambled broadcast signal 3 and transmitted through a broadcast transmission line 4. On the other hand, a descrambler 5 applies the conversion inverse to that at the transmission side and inverts the signal into a restored broadcast program signal 6 at the reception side. That is, the 2nd key signals 11, 12 are ciphered by the 3rd key signals 15, 16, the result is transmitted together with the broadcast program signal, the 4th key signal stored in advance and set to each subscriber receiver individually ciphers the 3rd key signals, the result is transmitted on each individual transmission line and each subscriber receiver reproduces the broadcast program signal through inversion.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a control information transmission method for controlling the scrambling of broadcast program signals in scrambled broadcasting that conceals broadcast program contents from users other than subscriber receivers, and in particular,
is designed to completely conceal the contents of broadcast programs.

BACKGROUND OF THE INVENTION In general, scrambled broadcasting is used to ensure that only receivers used by specific subscribers can receive broadcast programs.
The broadcast signal is scrambled and broadcast in advance, and only those who have subscribed can use a specific receiver or decoder to descramble and restore the scrambled broadcast signal and watch normal broadcast programs. A broadcasting format that allows for In such scrambled broadcasting, subscribers are given control information, ie, key information, from the subscriber side for normally restoring the scrambled broadcast signal. - In some cases, the receiver of a non-subscriber may be able to normally restore the scrambled broadcast signal, making it impossible to view the broadcast program.

However, if the scrambling mode is simple, even receivers that do not perform regular descrambling can
There are cases where it is possible to illegally view broadcast programs by making slight modifications or installing a circuit. Therefore, in order to realize completely scrambled broadcasting that completely eliminates such unauthorized viewing, it is essential to develop a system in which unauthorized viewing is extremely difficult.

There are two ways to strengthen scrambled broadcasting against unauthorized viewing.

(1) Making the scramble and descrambling aspects of broadcast signals complicated to make exploratory unauthorized viewing extremely difficult.

(2) Although the configuration of the descrambling circuit itself is not complicated, it is extremely difficult to decipher key information for descrambling.

Of the former, the one that complicates the descrambling aspect is
Because it is necessary to keep the price of legitimate receivers from increasing (8), there is a problem in that it is difficult to develop a scrambling method that makes legitimate receivers cheap and tampering receivers expensive.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned prior problems and, in particular, to
The present invention provides a control information transmission method for scrambled broadcasting that makes it possible to realize highly complete scrambled broadcasting by complicating only the configuration of the descrambling key information without complicating the configuration of the latter descrambling circuit itself. It's about doing.

That is, the control information transmission system of the present invention uses the eighth key signal to control the second key signal, which controls the change of the code sequence in the first key signal, which is composed of a predetermined pseudo-random code sequence for scrambling a broadcast program signal. The eighth key signal is encrypted and transmitted along the broadcast channel together with the scrambled broadcast program signal, and the eighth key signal is encrypted using a fourth key signal that is individually set and stored in each subscriber receiver in advance. (4) Each receiver decodes the eighth key signal using the fourth key signal stored in advance, and uses the eighth key signal to decode the eighth key signal. The broadcast program signal is descrambled by the predetermined pseudo-random code string of the set code sequence by decoding and controlling the second key signal, and the broadcast program signal is reproduced. .

EXAMPLES Below, the present invention will be described in detail by way of examples with reference to the drawings.

In general, in broadcasting by radio waves, the broadcast program signals themselves such as video signals, audio signals, and data are of course transmitted by broadcast radio waves, but the transmission of control information for descrambling, that is, key information, each has its own characteristics. The following transmission methods can be considered.

(1) A method in which key information is also transmitted via broadcast radio waves.

When transmitting key information by multiplexing it onto part of the broadcast radio waves,
Since the key information can be transmitted at a high speed, for example, at a speed of several tens to hundreds of kilobits/second, it is easiest to change or update the key information.

However, if all the key information is transmitted by broadcast waves, if an unauthorized recipient creates a special receiver and is able to decipher the key information, he or she will be able to view the entire broadcast program. Therefore, it becomes necessary to encrypt key information to be transmitted via broadcast radio waves, and to transmit key information for decoding the encrypted key information via a transmission path other than broadcast radio waves.

(2) A method of transmitting key information through a wired communication system such as a telephone line.

Since the key information is transmitted through a transmission path separate from the broadcast radio waves, security in preventing eavesdropping is increased.

Further, the information transmission speed after connection to a communication line is quite high, for example, on the order of several kilobits/second. That's right, phone number I
When using w, it is impossible to transmit key information to all Karo subscribers at the same time, and it is necessary to connect lines and transmit sequentially, so frequent updates of key information are required. This is difficult, and providing a dedicated transmission line for key information is economically disadvantageous.

(8) A method of transmitting key information using a distribution medium such as a card.

Distribution media include magnetic cards, semiconductor ROM (IJ-DO/RAM) IO cards, etc., and the amount of information per card varies depending on the medium, but is on the order of tens to hundreds of kilobits. Since key information transmission via distribution media is completely asynchronous with broadcast radio waves, the update speed of key information (7) information is extremely slow. Further, the content of the information transmitted by the distribution medium can be distributed centrally to all subscribers, or it is possible to individually distribute information with different content to each subscriber. Note that since distribution media can often be copied, it is necessary to take measures to prevent copying.

(4) A method in which encryption key information and decryption key information are fixedly built into the descrambling decoder itself.

Key information is built into the decoder in the receiver during system configuration, and the decoder itself is replaced to update the key information. Note that the built-in key information is in the form of semiconductor memory, etc.
In addition, it is necessary to make it difficult to read from the outside.

Part of it should be provided as scramble control information, that is, key information in scramble broadcasting! It's like a function.

(1) It cannot be directly detected by anyone other than the subscriber.

(2) Indirectly detecting key information from scrambled broadcast signals requires a long time (8) even if it is possible, so opportunities to use key information obtained through such indirect detection should be The key information is frequently updated so that the key information can be used immediately after the update in the authorized receiver.

(8) The key information given to each subscriber shall be kept private so that it cannot be used by others.

As described above, there are various control information transmission systems for scrambled broadcasting, but in the past, there was no system that had all the functions required for scrambled broadcasting. By integrating the above-mentioned features of the various embodiments, control information can be transmitted in a manner optimal for scrambled broadcasting as described in detail below.

First, FIG. 1 shows an example of the configuration of a control information transmission system for scrambled broadcasting according to the present invention. In the illustrated configuration,
An original signal, that is, a broadcast program signal 1, is converted into a scrambled broadcast signal 8 by changing its signal form by a scrambler 2, and then transmitted via a broadcast transmission path 4. Although radio waves are primarily considered as the broadcasting transmission line 4, the same applies when broadcasting to an unspecified number of subscribers via a wired transmission line. - On the receiving side, the descrambler 5 performs the opposite conversion to that on the transmitting side and converts it into a restored broadcast program signal 6. Note that the broadcast program signal may be in any format, such as a video signal, audio signal, or data signal.

The signal format conversion in the scrambler 2 or descrambler 6 described above is determined by the respective circuit configurations and algorithms, and the scramble control signal 7 or descramble control signal 8 supplied from the outside. That is, the scramble control signal 7 and the descramble control signal 8 are the keys to descrambling the broadcast program signal after each scramble, and the first control signal is used to directly process the broadcast program signal. This will be referred to as a key signal.

This first key signal may be the same or different on the transmitting side and the receiving side depending on the mode of signal processing inside the scrambler 2 and descrambler 5, but in the following explanation, Unless otherwise specified, they will be collectively referred to as the first key signal without distinguishing from any of them.

Although this first key signal differs depending on the scrambling method, it is generally set so that the form of the signal changes pseudo-randomly according to a certain rule. For example, for a digitized audio signal, as shown in FIG. A typical form of signal processing is to perform scrambling by adding modulo 2 to . The pseudo-random code string in this signal processing form is the above-mentioned first key signal, and on the receiving side, the pseudo-random signal generator 86 generates the same pseudo-random code string as on the transmitting side, and the signal is scrambled. The original signal can be completely restored by adding it to the received signal in the exclusive OR circuit δ7. Note that even when all analog video signals are scrambled, scrambling is performed in which the positional relationship of pixel signals and synchronization signals, or the amplitude, polarity, etc. of the signals are changed based on pseudo-random numerical values.

The pseudo-random code strings and pseudo-random numbers mentioned above are
The signals are generated by pseudo-random signal generators 9 and 10, and the generation speed is set to the speed required for signal processing. As such a pseudo-random signal generation circuit, a pseudo-random (PN) signal generator using a feedback shift register or the like is generally used.

The above-mentioned pseudo-random signal generator using a feedback shift register is configured, for example, as shown in FIG. Make it possible to obtain a random code string. This period becomes exponentially longer if the &ane of the shift register is increased.9 For example, when the clock frequency is 1 MHz, n=8
In this case, the period length is 255 μs, but if n≠82 (1B), the period length is 1.2 hours, and if n = 64, it is 5.8
X It will be 10' years. Now, the period of the pseudorandom code string is short, and the 0s and 1s of the digitized code string of the original signal are
If there is a bias of 9 in the probability of occurrence, for example, for the output code string of the exclusive OR circuit 88 in the configuration shown in the second diagram, observe bits at positions separated by the number of bits for one cycle of the pseudorandom code string. By doing so, it is possible to estimate the structure of the pseudorandom code string being added.

Therefore, in order to prevent the first key information from being decrypted in this way, it is necessary to increase the number of stages of the shift register to several tens or more and to make the cycle length of the code string sufficiently long.

Furthermore, in a pseudo-random signal generator that uses a feedback shift register, if the feedback connection logic is set, a code string of the same form will be repeatedly generated after an initial value is given to the shift register. Although this property is extremely important in ensuring that the same code string is generated on the transmitting side and the receiving side, it also has the following problems. Now, from the nature of the broadcast program signal, if it is possible to correctly estimate the part of the code string of the digitized original signal that is longer than the number of stages of the shift register, then the code string of the output transmission signal of the exclusive OR circuit can be estimated from the code string of the output transmission signal of the exclusive OR circuit. By subtracting the code string of the original signal, it is possible to correctly estimate the m-calculated pseudorandom code string. Therefore, if the estimation results are sequentially set in each stage of the shift register, the code string generated from the feedback shift register will completely match the code string on the transmitting side, and the first key information will be decoded. It turns out.

Generally, the redundancy of the signal waveform of broadcast program No. 13 is quite large, so if the key information is estimated or decoded in the manner described above, it will be difficult to completely prevent eavesdropping. As a measure to prevent such key information decoding, even if such key information decoding is successful, the manner in which pseudo-random code strings are generated is changed over time so that continuous eavesdropping for a long period of time becomes impossible. do. Further, if the time interval for changing the generation pattern is made shorter than the cycle length of the entire code string, the above-mentioned decoding using periodicity becomes impossible, so the number of stages of the shift register can be reduced.

- 10,000, the manner in which the pseudorandom code string is generated is changed, for example, as follows.

(1) Change the initial value of the shift register.

For example, if the initial value in the four-stage feedback shift register shown in Figure 8 is (1111), then
A code sequence as shown in l is obtained, and its period is 15 bits. (However, if the initial value is set in the middle of the shift and one page is read, a code string without periodicity is obtained as shown in FIG. 4 (bl). Note that the underlined code string is The changed part is the part where the initial value was changed.

(2) Change the wiring logic of the feedback shift register.

For example, as shown in FIG. 5, if the connection logic in a five-stage feedback shift register is changed, completely different code strings can be obtained even if the same initial value is set. Obtaining a different code string 'i by changing the wiring logic is possible if the feedback shift register has five or more stages.

In addition, in all the above-mentioned cases, the shift register is
It is possible to perform control by having a stage configuration and applying digital information of at most n bits to shift register circuits on the transmitting side and the receiving side, respectively. That is, the pseudo-random CPN (CPN) signal generator control information signals 11 and 12, which are composed of initial value data given to each stage of a one-stage shift register or data indicating the presence or absence of a feedback connection in each stage, are used as the second key information. I will call it that.

As a transmission path for the second key information 11, it is necessary to transmit it to the receiving side each time the state of the pseudo-random signal generator is updated, so from the viewpoint of transmission speed, it is transmitted on a part of the broadcast radio waves. is optimal.

However, since the second key information is also transmitted to the unauthorized recipient at the same time each time it is updated, the second key information itself is further encrypted and transmitted, and the decryption circuit 14 on the receiving side
For decryption, additional key information is required. The key information 15 and 16 for encrypting and decoding the key information itself will be referred to as eighth key information.

As the transmission path for the eighth key information 15 on the transmitting side, it is appropriate to use a separate transmission path different from the broadcast radio waves in order to prevent this eighth key information from leaking to anyone other than the subscriber. be. Moreover, this eighth key information does not need to be updated as frequently as the second key information.
It can be transmitted using a wired communication system such as a telephone line or a distribution medium such as a card. It is possible to store the eighth key information in the decoder itself, but if the eighth key information becomes known to someone other than the subscriber by some means and it becomes necessary to change it, the decoder The problem is that the device itself needs to be repaired or replaced.

In addition, when transmitting the eighth key information using a distribution medium such as a card, if the same card can be used in other receivers, there will be a charge if the card is duplicated. A big problem arises in terms of storage, etc. In order to avoid this problem, it is appropriate to make the key information for receiving scrambled broadcasting different for each player. However, the first
The key information must be common to all subscribing receivers due to restrictions on radio broadcasting, such as frequency allocation restrictions, and the second key information that controls this first key information is also unique to each subscriber. It must be common to all subscribers. Regarding the second key information, if there is sufficient data capacity on the key information transmission path, it is possible to set multiple types of change methods to obtain the same first key information and perform each change. The obtained second key information is transmitted to a plurality of pieces, and -10,000 to each subscriber e? ! It is also possible to set the inverse transformation method for each group divided into a number of groups.
Further, as a method of such inverse transformation, a method of adding different code strings for each group can be considered. However, regarding such an inverse conversion method, setting different key information for all subscribers requires increasing the control information transmission capacity by T-waves, so it is not a very desirable method. When recording the eighth key information for encrypting the key information on the distribution medium, the eighth key information itself is further encrypted, and the key information used for the encryption is different for each subscriber. It is also possible to make it into something.

The above-mentioned eighth key information is encrypted by the encryption circuit 17 in the configuration shown in the first diagram, and the writing device 2
2. Distribution media 28 such as magnetic cards or ROMs
recorded in On the receiving side, the distribution medium 28 is attached to the reading device 24, and the read output signal is sent to the decoding circuit 1.
8 and extracts the eighth key information 16t. The key information for encrypting this eighth key information 16 will be referred to as fourth key information, and will be unique key information that differs for each expert. This fourth key information is set and stored in advance in the decoder of each subscriber receiver, and when issuing and distributing distribution media, the fourth key information built in the decoder is used.
All the key information is recorded and managed in the subscriber-specific key information file 21 etc., and the eighth key information encrypted based on the recorded fourth key information is distributed on a distribution medium. .

As detailed above, at least four types of key information are required to fully function the control of broadcast program signal secrecy in scrambled broadcasting. Stated as follows.

The first key information continues to work during broadcasting.

The second key information needs to be updated while the first key information is not decoded from the scrambled and broadcast broadcast program signal. How much time is appropriate for the update period depends on the decryption technology of the fraudulent recipient, but
It is considered appropriate to set it within a few seconds. That is,
Even if the first key information can be decrypted by chance, if the first key information is updated within a few seconds, the decryption must be continued without any time for eavesdropping. Eavesdropping on the signal becomes virtually impossible. Furthermore, if digital information of several tens of bits is to be transmitted with a period of several seconds or less, the transmission of control information does not place a large burden on the broadcast wave transmission path (20).

Since the eighth key information is transmitted to each subscriber via a telephone line, distribution medium, etc., the update period is considered to be longer than the same amount every month. Since this eighth key information appears in the signal form as it is only inside the receiving decoder, the integrated circuit is designed so that the eighth key information appearing inside the receiving decoder cannot be read out to the outside. It is necessary to keep it. Note that there is no need to update the eighth key information unless it is known to a non-subscriber, so it is sufficient to use a transmission form that can be updated when it becomes known by chance and needs to be updated. become.

The fourth key information is fixedly stored inside the decoder when it is manufactured, and is not updated except when the decoder is repaired or replaced. Note that this fourth key information also needs to be prevented from being read out from the decoder.

Next, the information required for each of the above-mentioned key information will be explained.

The first key information is continuously used to scramble the broadcast program signal during the broadcast period, but it is generated separately on the receiving side using the second key information, so there is no need to transmit it.

The second key information has an amount of information corresponding to the number of stages of the shift register to be controlled. In addition, in order for the unauthorized recipient to know this second key information, it is necessary to repeat trial and error decryption using all similar key information that may be used. It is necessary to make the update period longer than the update period of the key information. For example, if trial and error for 1 bit of key information takes 0.1 seconds, trial and error for 4 bits of key information will take 0.1 x 2'=
It takes 1.6 seconds, and 25.6 seconds for trial and error for 8-bit key information, and 1.6 seconds for 16-bit key information.
．． It will take 8 hours. Therefore, if the amount of second key information is set to be larger than about 16 bits, such trial-and-error decoding becomes impossible in practice.

Regarding each of the eighth and fourth key information, even if the key information is fully decrypted for a long time through repeated trial and error as described above, the update period of the key information is long, so the result of the decryption can be used to prevent eavesdropping. There is a risk of For example, the DES standard (Data E
ncryptin 5 standard),
Since the amount of key information is specified as 64 bits, and the actual amount excluding pits for error checking is 56 bits, it is safe if the amount of information is kept at this level. In addition, the number of subscribers to which these key information should be transmitted needs to be individually assigned to approximately tens of millions of subscribers, so from this point of view,
It is sufficient to have an information amount of 6 bits, that is, about 2"=6.7 x 107 bits.

As described above, according to the present invention, the mode of transmitting the control information, that is, the key information necessary for restoring the scrambled broadcast program signal, to the receiving side safely, that is, so as not to be decoded by non-subscribers, has been described in detail. In scrambled broadcasting, it is necessary to have a function to control the operation of the receiver according to the contents of the subscriber's contract (28) due to the connection with the charge collection system for paid broadcasting. For example, it is necessary to have a function that stops the receiver's descrambling function if the contracted broadcasting station, reception period, type of viewing program such as a special program with a special charge, etc. do not comply with the contract contents. . To provide this kind of functionality, control information related to the contract content is used to transmit the eighth key information and is included in the distribution data on the distribution medium. It is also conceivable to transmit information regarding the program, a broadcasting station code, a date code for the year, month, day, etc. in the transmitted data, and to perform descrambling control after collating the control information on the receiving side. FIG. 6 shows an example of the structure of transmission data in such a case, and FIG. 7 shows an example of the structure of distribution data. Note that when the capacity of information transmission by broadcast radio waves is large, it is also possible to carry out radio addressing, in which information such as a number indicating the identity of each subscriber is carried on the radio waves and transmitted to individually control receiving decoders. An example of the structure of transmission data in such a case is also shown in FIG. On the receiving side, it is possible to control the descrambling operation according to the result of checking the subscriber-specific information and the subscriber-specific information in the distribution data such as the lever (24) number. . The contents of such control include operating the decoder of a receiver with a contract, and stopping the operation of the decoder of a receiver whose contract has expired or has been stolen. In the former case, the amount of data to be transmitted is large, the transmission time is long, and the receiver must always be in a receiving state. - In the latter case, the amount of data to be transmitted is small, and there is no problem compared to the former case even if the information is not transmitted to the receiver that is not in the receiving state, and it is considered easier to implement than the former case. .

FIG. 8 shows a configuration example of a reception decoder that adds the above-mentioned fee collection-related information processing function to the scrambled broadcast control information transmission system having the basic configuration shown in FIG.

As the encryption method for realizing the control transmission function according to the present invention, any encryption method can be used as long as it is possible to encrypt and decrypt all information of the transmission data within the transmission interval of the transmission data. Further, since it is not necessary to encrypt and decrypt the second key information and the eighth key information at the same time, the same encryption method can be used alternately in the same circuit in full time division. Note that a specific example of the encryption method is the above-mentioned DES method.

Further, as a circuit for generating a pseudo-random code string constituting the first key information, an example using a feed batter shift register has been mainly explained, but the circuit is not limited to this example, and for example, as shown in FIG. A circuit generated using a block encryption circuit such as the above can also be used in the same manner. Note that the above-mentioned DES method or the like can be used as this encryption method.

Effects As is clear from the above explanation, the advantages and effects of the scramble broadcasting control information, ie, key information transmission system according to the present invention, are as follows.

(1) Regardless of whether the broadcast program signal to be scrambled is a video signal, audio signal, data signal, etc.

Regardless of the signal format, the control information transmission system can be realized with a similar configuration.

(2) In order to prevent unauthorized recipients from decrypting the key information by taking advantage of the redundant warning nature of the transmitted signal, the content of the key information is updated over time, and the Since the control information can be transmitted to the receiving side at high speed, the key information can be updated frequently to improve security.

(8) Encrypting the control information for updating the key information mentioned above,
By transmitting the encrypted control information using a transmission path different from the control information transmission method for decoding it, the chances of leakage to non-subscribers can be greatly reduced.

(4) The first key information that directly controls the scrambling of the broadcast program signal can be transmitted using the second key information without directly encrypting it using an extremely small number of information devices.

(5) Key information for encrypting control information transmitted via broadcast radio waves can also be updated at necessary times.

(6) According to the configuration of the control information transmission system according to the present invention, key information for encrypting distributed data can be individually set for each receiver, and distribution transmission media such as cards can be duplicated. Even in such a case, it is possible to prevent other receiving decoders from operating depending on the duplicated card or the like.

(7) In addition to controlling broadcast program signal scrambling,
Control information related to charge collection in pay broadcasting can also be transmitted in a comprehensive manner, making it possible to realize a scrambled broadcasting system that is highly flexible in terms of operation.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of a control information transmission system for scrambled broadcasting according to the present invention, and FIG. 2 is a block diagram showing an example of the configuration of a scrambling circuit based on addition of pseudo-random code strings. 4(a) and 4(b) are block diagrams showing an example of the configuration of a pseudorandom signal generator using the feedback shift register (28), and FIGS. 4(a) and 4(b) are examples of output code strings of the pseudorandom signal generator. 5th line diagram showing each
Figures (a) and (bl are block diagrams showing other configuration examples of a pseudo-random signal generator using the same feedback shift register, respectively;
b) is a diagram showing an example of the structure of the transmission data, FIG. 7 is a diagram showing an example of the structure of the distribution data, FIG. 8 is a block diagram showing an example of the structure of the receiving decoder, FIG. 9 is a block diagram showing an example of the configuration of a pseudorandom signal generator using the same block encryption circuit. 2... Scrambler, 4... Broadcast transmission line, 5-61
...Descrambler, 5, 10, 82, 86
, 60-2...pseudo random signal generator, I8.1?
...Encryption circuit, 14, 18, 152, 58-
...Decryption circuit, 21-...Subscriber individual file, 2t.
・Honoring device, 28...Distribution medium, 24...Seed, picking device, 38, 87, 44, 45, 46...Exclusive OR circuit, 40, 60-1, 62...Initial value setting circuit , 4-1-1 to 41-4...switch, 42 ・
Shift register, 54, 55-1, 58, 63・
・Key signal generator, 55-2・Contract content data extraction circuit, 56 ・81 Person number-call information extraction circuit, 57...Send i3 data extraction circuit, 5! J...Tecoder wholesale control circuit,
64... Input cover 7a circuit, 65... Block encryption circuit. Patent Applicant Japan Broadcasting Corporation - Ricl- \ノ \ノ() () -4ふ\ノ () Figure 9, page 1 continued 0 Inventor Masanori Saito Kinuta, Setagaya-ku, Tokyo] Research Institute -9A'J- Chome 1 Hata No. 11 Japan Broadcasting Corporation Comprehensive Technical Procedures Amendment 1
, February 16, 1980 1, Incident Indication 1988 Patent Application No. 24.21.84. No. 2, Invention name control information transmission method 3, Relationship with the case of the person making the amendment Patent applicant T435) Japan Broadcasting Corporation "Brief explanation of drawings" column and Drawing 7, Contents of amendment (as attached) Details The scope of the patent claims of the document is amended as follows. [2.Claim L: A second key signal P for controlling the change of a code sequence in a first key signal consisting of a predetermined pseudo-random code sequence for scrambling a broadcast program signal, and an eighth key signal for encrypting. The eighth key signal is then transmitted along the broadcast transmission path together with the scrambled ++tI K+2 broadcast program signal, and the eighth key signal is encrypted using a fourth key signal that is individually set and stored in each subscriber receiver in advance. 7J each [for a single receiver,
The code sequence set by decoding the eighth key signal using the fourth key signal stored in advance, and controlling by decoding the eighth key signal (ii) using the eighth key (No. 1). 9. A control information transmission system for scrambled broadcasting, wherein the broadcast program signal is descrambled using the predetermined pseudo-random code string. 9. The transmission system according to claim 1. In,
A control information transmission system for scrambled broadcasting, characterized in that the first and second key signals are changed in short cycles, and the eighth key signal is changed in long cycles. 8. In the transmission system according to claim 1 or 2, the first (1) u signal is updated by updating the initial value of the pseudorandom code string generator with the second key signal. 1. A control information transmission system for scrambled broadcasting, which is characterized in that it controls changes in code sequences in a scrambled broadcast. 4. In the transmission system as set forth in claim 1 or 2 of the claims, the connection theory BII of the pseudo-random code string generator consisting of a feedback shift register is changed by the second key signal. "Control information transmission method for scrambled broadcasting characterized by controlling the change of code sequence in a key signal 0" 2. "Of the former" in page 4, line 19 of the specification. In lines 19 and 20 of the same page, ``to do it'' is corrected to ``how to do it.'' 8 In the 5th line of the same page, ``difficult'' is corrected to ``necessary and difficult,'' and in the 17th line of the same page, ``broadcasting path'' is corrected to ``broadcasting transmission path.'' 4. Correct "several tens" to "several hundred bits" on page 8, line 18. 5. Correct ``to do'' on page 9, line 20 of the same page to ``to do'' to -1. 6 Delete ``respectively'' on page 11, line 15 of the same page. 7. Correct "logic circuit" in lines 1 to 12 of page 12 to "OR circuit." 8 Change the "initial value" on page 14, line 17 of the same page to "same initial value"
Correct. 9. Corrected "kotomo" in line 14 of page 19 to "koto", and changed "inverse conversion method" in lines 17 to 18 of the same page to "second
``Method of transmitting multiple pieces of key information.'' 10 On page 20, line 5 of the same page, "kotomo" was corrected to "koto", on line 6 of the same page, "encryption" was deleted, and on line 18 of the same page, "by subscriber" was changed to " Corrected to "Individual subscriber". 11. On page 28, lines 1B to 19, "Decryption is not possible" is corrected to "Decryption is not possible within the update period." 12 24m 5th row f” Encryptin J
E [Corrected Encryption J, and changed “i.e. 2 = 6.7X] OJ in line 12 of the same page to [(
In other words, it corresponds to 2 = 6.7 x 10 IJn people). 18 The ``reception period'' in the second line of page 26 of the same page is corrected to ``contract period,'' and the ``contract content'' in the 8th line of the same page is corrected to ``broadcast signal content.'' 14, page 27, line 11, after "Dekiru.", add the following. ``However, the key 68 in Figure 9 is different from the first to fourth keys mentioned above and is set in advance, but it can also be used in common with the eighth key. There is.” ]5. On page 28, line 16, [encryption] is corrected to ``encrypted and transmitted.'' On page 28, line 17, [using,] is corrected to ``because it is generated using.'' 16 Correct page 80, line 16 to page 28, line 1B as follows: 1.Broadcast program signal, 2.Scrambler, 8.
... Scrambled broadcast signal, 4... Broadcast transmission path, 5°61... Descrambler, 6... Restored broadcast program signal, 7... Scramble control signal (part of first key information), 8... Descramble control signal @ (part of the first key information), 9, 10, 82.86, 60-2... Pseudo random signal generator,] 1, 12... Second Key information, 1
3.17... Encryption circuit, 14°18.52.58.
...Decryption circuit, t5.16...Eighth key information, 19.
20... First key information, 21... Subscriber individual key file, 22... Writing device, 28... Distribution medium, 2
4...Reading device, 25°36...Control information, 27
．． 30... Digital code string 81s85... Pseudo random code string, 88°87.44, 45.46...
Exclusive OR circuit, 40.60-1.62...Initial value setting circuit, 41-1. ~41-4.51... Switch, 42... Shift register, 48... PM signal output, 47... Broadcast reception signal, 48... Distribution data, 4
9...Operation data, 5O...Device number, 54.55
-1.58°68...Key signal memory circuit, 55-2.
... Contract content data extraction circuit, 56... Subscriber number information extraction circuit, 57... Transmission data extraction circuit, 59...
・Decoder control circuit, 64...Manual buffer circuit, 6
5... Block encryption circuit, 66... Pseudo random signal output. ] Among the 71 drawings, Figures 1, 7, and 8 are corrected as shown in the attached corrected drawings. () Figure 1

Claims (1)

[Claims] 1. A second key signal for controlling a change in a code sequence in a first key signal consisting of a predetermined pseudo-random code sequence for scrambling a broadcast program signal is encrypted with an eighth key signal. , along with the scrambled broadcast program signal), and encrypts the eighth key signal using a fourth key signal that is individually set and stored in each subscriber receiver in advance. Each participating receiver decrypts the eighth key signal using the fourth key signal stored in advance, and decodes the second key signal using the eighth key signal. A control information transmission system for scrambled broadcasting, characterized in that the broadcast program signal is reproduced by being descrambled by the predetermined pseudo-random code string of a code sequence set by decoding and controlling a key signal. . i. In the transmission method according to claim 1, the first and second key signals are changed in short cycles, and the eighth key signal is changed in long cycles. A control information transmission method for scrambled broadcasting characterized by:龜 In the transmission method according to claim 1 or 8, the initial value of the pseudorandom code string is set to the second
1. A control information transmission system for scrambled broadcasting, characterized in that a change in a code sequence in the first key signal is controlled by updating p with a key signal. 4. In the transmission system according to claim 1 or 8, by changing the connection logic υ of a pseudorandom code string generator consisting of a feedback shift register, Control information transmission system for scrambled broadcasting, characterized by controlling changes in code sequences in key signals