JP3928502B2 - Playback control method and transmission / reception method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a reproduction control method for receiving and reproducing an image transmitted by digital television broadcasting using a satellite, for example.as well asHow to send and receiveTo the lawIn particular, it relates to the protection of operating profits and copyrights.
[0002]
[Prior art]
Realization of digital television broadcasting in which a compressed digital video signal is transmitted using a satellite is being studied. When digital television broadcasting using such satellites is realized, various interactive services are possible in addition to television broadcasting that unilaterally provides programs from a broadcasting station to a large number of viewers. Would. That is, in digital television broadcasting using a satellite, it is possible to increase the number of channels. For this reason, a specific viewer can be selected and a specific service can be performed only for a specific person. For example, when a specific video source is ordered, a program of the video source is sent to the person who ordered the video source. Using such a service, video software sent by digital television broadcasting will be purchased and borrowed for a certain period or number of times.
[0003]
[Problems to be solved by the invention]
In order to realize such a service, in order to protect copyright and business profits, it is necessary to allow reproduction only when a predetermined condition is satisfied. That is, when video software is purchased by digital television broadcasting using a satellite, it is necessary to make it reproducible only when the condition “paid” is satisfied. In addition, when playing back video software sent by digital television broadcasting using satellites in a limited number of times, it is necessary to be able to play back only when the condition “the number of times of playback is within a predetermined value” is satisfied. is there. When renting video software sent by digital television broadcasting using a satellite for a limited period, it is necessary to make it reproducible only when the condition “being lent” is satisfied.
[0004]
A system for transmitting a digital video signal using a digital line has been considered. Even in such a system, various interactive services can be realized as in the case of digital television broadcasting using satellites. In such a service using a digital line, in order to protect copyright and business profits, it is necessary to be able to reproduce only when the conditions are satisfied.
[0005]
  Accordingly, an object of the present invention is to provide a reproduction control method capable of performing reproduction only when predetermined conditions are satisfied when distributing video software via digital broadcasting or a line.as well asHow to send and receiveThe lawIt is to provide.
[0006]
[Means for Solving the Problems]
  The present invention is a reproduction control method for controlling reproduction of an information signal that has been encrypted and recorded on a recording medium,
  The time information generated and transmitted by the information signal provider is received,
  The received time information is supplied to the watch,
  Based on the additional information generated and transmitted by the information signal provider, the reproduction condition information indicating the reproduction period or period of the recorded information signal is recorded on the recording medium,
  Playback condition informationAnd current time information from the clockThe reproduction control method is characterized in that the reproduction of the recorded information signal from the recording medium and the cancellation of the encryption applied to the reproduced information signal are controlled.
[0007]
  The present invention is a method of transmitting and receiving information signals,
  On the sending side,
  Transmit information signals to the receiver,
  Transmit time information generated by the information signal provider,
  Additional information that is generated by the information signal provider and used when recording the reproduction condition information indicating the reproduction period or period of the information signal on the recording medium in the receiving device.AsTransmit
  On the receiving side,
  Receive the transmitted time information,
  The received time information is supplied to the watch,
  Receiving the transmitted information signal,
  Record the received information signal on a recording medium with encryption,
  Receive the transmitted additional information,
  Recording playback condition information on a recording medium based on the received additional information,
  Playback condition informationAnd current time information from the clockThe transmission / reception method is characterized in that the reproduction of the recorded information signal from the recording medium and the release of the encryption applied to the reproduced information signal are controlled.
[0011]
The transmitted signal is encrypted and recorded. Then, the reproduction condition is transmitted, and the reproduction condition is stored in the reproduction condition storage memory. At the time of reproduction, whether to decrypt the code is controlled according to the conditions stored in the reproduction condition storage memory. Thereby, it is possible to perform reproduction only when predetermined conditions are satisfied.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
a. Overall configuration of digital television broadcasting system
FIG. 1 shows an example of a digital television broadcasting system using a satellite to which the present invention can be applied. In FIG. 1, 101 is a broadcasting station, and 102 is a digital signal receiver in each home. The digital signal receiver 102 cancels the scramble applied to the signal from the broadcasting station and decodes MPEG (Moving Picture Image Coding Experts Group) or MPEG2, and purchases and rents the video software through the public line 106. And a video recording / reproducing apparatus for recording / reproducing the transmitted video signal.
[0013]
As a video recording / reproducing apparatus provided in the digital signal receiver 102, for example, a digital VTR that compresses a digital video signal and records it on a magnetic tape is used. A cassette (referred to as MIC) 104 with a memory is attached to the digital VTR. As will be described in detail later, access conditions such as “full access”, “reproduction not possible”, “N times reproduction permitted”, and “permission permitted until expiration date Y” are stored in the memory of the cassette 104 with memory. The
[0014]
The digital signal receiver 102 is provided with an encryption circuit and a decryption circuit. On the magnetic tape of the cassette 104 with memory, the video signal is recorded without being encrypted or encrypted according to the access conditions stored in the memory of the cassette 104 with memory. Also, according to this access condition, the reproduction signal is reproduced without being decrypted or decrypted from the magnetic tape of the cassette 104 with memory.
[0015]
A monitor 105 is connected to the digital signal receiver 102. The received signal is decoded by the digital signal receiver 102, and the decoded signal is supplied to the monitor 105. In addition, a video signal is reproduced from the magnetic tape of the cassette 104 with memory, and a reproduced image is displayed on the monitor 105 as the reproduction signal.
[0016]
In such a system, for example, video software is purchased or rented as follows.
[0017]
When purchasing or renting video software, the user orders video software from the broadcasting station 101 through the public line 106. When video software is ordered, the broadcast station 101 selects the video software, and the video software signal is transmitted from the broadcast station 101.
[0018]
Video software orders include video software purchases, rentals with a limited number of viewing times or viewing time limits. The transmission signal is, for example, a digital video signal compressed based on MPEG. This video signal may be sent in real time or may be transmitted after being compressed on the time axis.
[0019]
A signal from the broadcast station 101 is received by the digital signal receiver 102 in each home via the satellite 107. A signal transmitted via the satellite 107 is decoded by the digital signal receiver 102. This video signal can be recorded on the magnetic tape of the cassette 104 with memory.
[0020]
When video software is purchased, the video signal recorded on the magnetic tape of the memory-equipped cassette 104 by the digital signal receiver 102 can be reproduced at any time if a fee is paid. When the video software is rented with a viewing limit, the video signal recorded on the magnetic tape of the memory-equipped cassette 104 can be reproduced a predetermined number of times. When the video software is rented with a viewing time limit, the video signal recorded on the magnetic tape of the cassette 104 with memory can be reproduced until the determined time limit.
[0021]
As described above, in a system in which video software is purchased or rented with a viewing frequency limit or a viewing time limit, it is necessary to protect copyright and operating profit. Therefore, it is conceivable to control recording / reproduction under the following conditions.
[0022]
(1) If a certain condition, for example, the condition that the fee has been paid, is satisfied, the broadcasted program can be recorded and reproduced unconditionally. When video software is purchased, if the fee for the software has been paid in advance, this is control for allowing the broadcasted program to be freely recorded and reproduced.
[0023]
(2) The broadcasted program is once recorded, but the recorded program can be reproduced under certain conditions thereafter, for example, a fee is paid later. In the case of purchasing or renting video software, this is a control for confirming the delivery of the fee and enabling the reproduction when the fee is paid after recording the broadcasted program.
[0024]
(3) Record the broadcast program and make it reproducible only a certain number of times. This is control for allowing video software to be viewed up to a predetermined number of times of use when the video software is rented with a limited number of viewing times.
[0025]
(4) Record the broadcast program and make it reproducible only for a certain period. This is control for allowing video software to be viewed up to a predetermined period when it is rented with a viewing deadline.
[0026]
b. Example of home reception system
FIG. 2 shows an example of the digital signal receiver 102A in each home. A cassette 104A with a memory is mounted on the digital signal receiver 102A. A magnetic tape 40 is wound around the cassette 104A with memory, and a memory 29 is provided. The memory 29 stores access conditions as will be described later.
[0027]
The digital signal receiver 102A is provided with a modem 31. The modem 31 is provided to connect the access control circuit 28A to the public line 106. The access control circuit 28A performs an encryption process and a decryption process depending on the order form of video software such as purchase of video software, rental with a limited number of viewing times or viewing time limit, and whether or not a fee has been paid. It is something to control. The access control circuit 28A can read / write data from / to the memory 29 of the cassette 104A with memory.
[0028]
In FIG. 2, a digital television signal transmitted from a broadcasting station 101 (FIG. 1) via a satellite 107 (FIG. 1) is received by an antenna 103. A digital television signal sent from the broadcasting station 101 via the satellite 107 is compressed based on MPEG. Further, the digital television signal is scrambled so that only a specific contracted viewer can receive it.
[0029]
A reception signal of the antenna 103 is supplied to the tuner circuit 20. The tuner circuit 20 selects a signal of a predetermined channel. The output of the tuner circuit 20 is supplied to the descrambler 21A. The descrambler 21A releases the scramble of the digital video broadcast.
[0030]
The digital video broadcast signal may include information indicating that the fee has been paid, and additional information such as a rental deadline and a rental frequency limit. This additional information is decoded by the descrambler 21A. Furthermore, time information is included in the received signal. In order to update the clock 27, this time information is supplied from the descrambler 21A to the clock 27.
[0031]
The output of the descrambler 21A is supplied to the encryption circuit 22. Encryption on / off of the encryption circuit 22 is controlled by the access control circuit 28A. When encryption is turned off, the video signal descrambled by the descrambler 21A is supplied to the recording / reproducing circuit 23A as it is. When encryption is turned on, the video signal descrambled by the descrambler 21A is encrypted by the encryption circuit 22 and supplied to the recording / reproducing circuit 23A.
[0032]
The output of the recording / reproducing circuit 23A is supplied to the head 24. A digital video signal is recorded on the magnetic tape 40 by the head 24.
[0033]
During reproduction, the signal on the magnetic tape 40 is reproduced by the head 24. The output of the head 24 is supplied to the recording / reproducing circuit 23A. The output of the recording / reproducing circuit 23A is supplied to the decryption circuit 25.
[0034]
The decryption circuit 25 is controlled to be turned on / off by the access control circuit 28A. When decryption is turned off, the reproduction signal from the recording / reproducing circuit 23A is supplied to the decoder 26 as it is. When the decryption is turned on, the reproduction signal from the recording / reproduction circuit 23A is decrypted by the decryption circuit 25 and supplied to the decoder 26. The decoder 26 performs, for example, MPEG decoding. The output of the decoder 26 is supplied to the monitor 105.
[0035]
c. Processing during recording
The video software order is made by the user interface 30 using the public line 106. When purchasing video software, if the fee is paid, the transmitted video signal is recorded on the magnetic tape 40 without being encrypted, and “full access information” is recorded on the memory 29. . In this case, since it is recorded without being encrypted, it can be reproduced at any time.
[0036]
In the case of renting video software with a limit on the number of times of viewing, if the fee is paid, the transmitted video signal is encrypted by the encryption circuit 22 and “N times reproduction permission information” is stored in the memory 29. Is recorded. At the time of reproduction, the “N times reproduction permission information” in the memory 29 is decrypted a predetermined number of times.
[0037]
When the video software is rented with a viewing time limit, if the fee is paid, the transmitted video signal is encrypted by the encryption circuit 22 and “playback permission information until the time limit Y” is stored in the memory 29. Is recorded. At the time of reproduction, decryption is performed until the expiration date by the “reproduction permission information until expiration date Y” in the memory 29.
[0038]
Hereinafter, such control will be described in detail with reference to the flowchart of FIG.
[0039]
When the user purchases video software or rents the video software with a viewing time limit or a viewing time limit, an input is given to the access control circuit 28A by the user interface 30. When an input is given to the access control circuit 28A by the user interface 30, the access control circuit 28A is connected to the broadcast station 101 via the modem 31 and the public line 106 (step S1).
[0040]
When the access control circuit 28A is connected to the broadcasting station 101, the contract status is checked (step S2). If there is no contract, processing such as warning and line disconnection is performed (step S3).
[0041]
If the contract is made, it is checked whether the video software is desired to be purchased or whether the rental is desired with a viewing time limit or a viewing time limit (step S4). If the user wishes to purchase, it is checked whether or not the fee has been paid in advance or whether or not the fee is to be paid immediately (step S5).
[0042]
If the user wishes to purchase and the fee is paid in advance or the fee delivery operation is performed, the access control circuit 28A sends a control signal for turning off the encryption circuit 22 to the encryption circuit 22, and Full access information is written in the memory 29. Since the encryption circuit 22 is turned off, the video signal scrambled by the descrambler 21A is recorded on the magnetic tape 40 without being encrypted (step S6).
[0043]
If the user wishes to purchase and the fee is not paid in advance or the fee delivery operation is not performed, the access control circuit 28A sends a control signal for turning on the encryption circuit 22 to the encryption circuit 22. Then, “reproduction impossible information” is written in the memory 29. Since the encryption circuit 22 is turned on, the video signal descrambled by the descrambler 21A is encrypted and recorded on the magnetic tape 40 (step S7).
[0044]
If the purchase of video software is not desired in step S4, it is checked whether or not the rental is desired with a limited number of viewings (step S8). If the rental is desired with the viewing number limit, it is checked whether or not the fee is paid in advance or whether or not the fee is paid immediately (step S9).
[0045]
If it is desired to rent with a limited number of viewings and the fee is paid in advance or the fee delivery operation is performed, the access control circuit 28A sends a control signal to turn on encryption to the encryption circuit 22. At the same time, “N times reproduction permission information” is written in the memory 29. Since the encryption circuit 22 is turned on, the video signal descrambled by the descrambler 21A is encrypted and recorded on the magnetic tape 40 (step S10).
[0046]
If it is desired to rent with a limited number of viewings and the fee is not paid in advance or the fee delivery operation is not performed, the access control circuit 28A sends a control signal for turning on the encryption circuit to the encryption circuit 22. To the memory 29, and “reproduction impossible information” is written in the memory 29. Since the encryption circuit 22 is turned on, the descrambled video signal is encrypted and recorded on the magnetic tape 40 (step S7).
[0047]
If it is determined in step S8 that the rental with viewing number restriction is not desired, it is checked whether or not the rental with viewing time limit is desired (step S11). When the rental with viewing time limit is desired, it is checked whether or not the fee is paid in advance or whether or not the fee is paid immediately (step S12).
[0048]
If it is desired to rent with a limited number of viewings and the fee is paid in advance or the fee delivery operation is performed, the access control circuit 28A sends a control signal to turn off encryption to the encryption circuit 22. At the same time, “reproduction permission information until time limit Y (year: month: day)” is written in memory 29. Since the encryption circuit 22 is turned on, the video signal descrambled by the descrambler 21A is encrypted and recorded on the magnetic tape 40.
[0049]
If the fee is not paid in advance or the fee delivery operation is not performed, the process goes to step S7, and the access control circuit 28A sends a control signal for turning on the encryption to the encryption circuit 22 and the memory 29. "Reproduction impossible information" is written in Since the encryption circuit 22 is turned on, the video signal descrambled by the descrambler 21A is encrypted and recorded on the magnetic tape 40.
[0050]
As described above, when video software is purchased, when a fee is paid, the video signal is recorded without being encrypted, and “full access information” is written in the memory 29. If the video software is purchased and no fee is paid, the video signal is encrypted and recorded, and the non-reproducible information is recorded in the memory 29.
[0051]
In the case of renting video software with a limited number of viewing times, when a fee is paid, the video signal is encrypted and recorded, and “N times reproduction permission information” is written in the memory 29. When the video software is rented with a viewing time limit, when the fee is paid, the video signal is encrypted and recorded, and “playback permission information until the time limit Y” is written in the memory 29. When video software is rented with a viewing limit or a viewing time limit, if no fee is paid, the video signal is encrypted and recorded, and “unreproducible information” is recorded in the memory 29. .
[0052]
d. Processing during playback
Next, processing during reproduction will be described with reference to the flowchart of FIG.
[0053]
First, a case where video software purchased by paying a fee is reproduced will be described. As described above, when video software is purchased, if a fee has been paid, the video signal is recorded without being encrypted and full access information is written in the memory 29 (see step S6). . When the signal recorded on the magnetic tape 40 is reproduced, the information recorded in the memory 29 is read (step S21). If you have purchased video software and paid a fee, you can get “Full Access Information” at this time.
[0054]
It is checked whether or not the information from the memory 29 is “reproduction impossible information” (step S22). If it is not “reproduction impossible information”, it is checked whether or not it is “N times reproduction permission information” (step S23). If it is not “N times reproduction permission information”, it is checked whether or not it is “reproduction permission information until time limit Y” (step S24). Whether it is “full access information” or not is checked (step S26).
[0055]
If the video software has been purchased and the fee has already been paid, it is determined in step S26 that it is “full access information”. If it is found that it is “full access information”, the video signal is reproduced as it is (step S27). When video software is purchased, if the fee is paid, the video signal recorded on the magnetic tape 40 is not encrypted, so that the signal from the magnetic tape 40 does not need to be decrypted.
[0056]
If the information from the memory 29 is not “Non-reproducible information”, “N-time reproduction permission information”, “Reproduction permission information until time limit Y”, “Reproducible information” or “Full access information”, access control The circuit 28A sends a control signal for turning off decryption to the decryption circuit 25, and reproduction is impossible. (Step S28).
[0057]
Next, a case where video software is rented with a viewing deadline will be described. When paying a fee and renting video software with a viewing time limit, the video signal is encrypted and recorded on the magnetic tape 40, and “playback permission information until the time limit Y” is written in the memory 29. (See step S13). It is checked whether or not the information from the memory 29 is “reproduction impossible information” (step S22). If it is not “reproduction impossible information”, it is checked whether or not it is “N times reproduction permission information” (step S23). If it is not “N times reproduction permission information”, it is checked whether it is “reproduction permission information until time limit Y” (step S24). When paying a fee and renting video software with a viewing time limit, the information from the memory 29 becomes “reproduction permission information until time limit Y”.
[0058]
If the video software is rented with a viewing time limit and the fee has already been paid, it is determined in step S24 that the information from the memory 29 is “reproduction permission information until time limit Y”. If it is found that “reproduction permission information until time limit Y”, this time limit Y is compared with the current year, month, and day, and it is determined whether or not the time limit Y has passed (step S29).
[0059]
If the time limit has passed, the access control circuit 28A sends a control signal for turning off decryption to the decryption circuit 25, and reproduction is disabled (step S28).
[0060]
If it is within the time limit, the access control circuit 28A sends a control signal for turning on decryption to the decryption circuit 25. Therefore, the encrypted video signal recorded on the magnetic tape 40 is decrypted and reproduced (step S30).
[0061]
Next, a case where the video software is rented with a fee limit and a viewing frequency limit will be described. When paying a fee and renting video software with a viewing limit, the video signal is encrypted and recorded on the magnetic tape 40, and "N times reproduction permission information" is written in the memory 29. (See step S10). It is checked whether or not the information from the memory 29 is “reproduction impossible information” (step S22). If it is not “reproduction impossible information”, it is checked whether or not it is “N times reproduction permission information” (step S23). When paying a fee and renting video software with a viewing time limit, the information from the memory 29 is “N times reproduction permission information”.
[0062]
If the video software is rented with a viewing number limit and the fee has already been paid, it is determined in step S23 that the information from the memory 29 is “N times reproduction permission information”. If it is determined that the information is “N times reproduction permission information”, it is determined whether or not N times of reproduction has been completed (step S31).
[0063]
If the N times of reproduction have been completed, the access control circuit 28A sends a control signal for turning off the decryption to the decryption circuit 25, and the reproduction becomes impossible (step S28).
[0064]
If N times of reproduction has not been completed, the reproduction impossible information already stored in the memory 29 is rewritten to “N−1 times reproduction permission information” (step S32). Then, the access control circuit 28A sends a control signal for turning on decryption to the decryption circuit 25. Therefore, the encrypted video signal recorded on the magnetic tape 40 is decrypted and reproduced (step S30).
[0065]
Next, a case where a fee is not paid at the time of purchase will be described. If the fee is not paid at the time of purchase, the video signal is encrypted and recorded as described above, and “unreproducible information” is recorded in the memory 29 (see step S7). In this case, a fee can be paid at the time of reproduction, and video software can be purchased or rented with a limited number of times or with a limited time.
[0066]
First, a case will be described in which video software is purchased by paying a fee during playback.
[0067]
If the information from the memory 29 is “unreproducible information”, the access control circuit 28A is connected to the broadcast station 101 (step S33). If you wish to purchase video software, you will be charged a purchase fee. It is checked whether or not the purchase fee of the video software has been paid (step S34), and when the purchase fee is paid, the “non-reproducible information” already stored in the memory 29 is rewritten to “reproducible information” (step S34). S35).
[0068]
As described above, when the fee for purchasing the video software is paid, the “reproduction permission information” is recorded in the memory 29. When “reproducible information” is recorded in the memory 29, the access control circuit 28 A sends a control signal for decryption to the decryption circuit 25. Therefore, the encrypted video signal recorded on the magnetic tape 40 is decrypted and reproduced (step S30).
[0069]
When “reproducible information” is written in the memory 29, it is determined in step S25 that the information in the memory 29 is “reproducible information” during the subsequent reproduction. The encrypted video signal from 40 is decrypted and played.
[0070]
Next, a description will be given of a case where the video software is rented with a viewing frequency limit at the time of playback.
[0071]
If the information from the memory 29 is “unreproducible information”, the access control circuit 28A is connected to the broadcast station 101 (step S33). Here, if the video software is desired to be rented with a viewing limit, a rental fee for N times of playback is paid. It is checked whether or not the purchase fee of the video software has been paid (step S34). If the purchase fee has not been paid, it is checked whether or not to rent with a viewing number limit (step S36). When renting with a limited number of viewings, N viewing fees are paid.
[0072]
It is checked whether or not the viewing fee for N times has been paid. If the viewing fee for N times has been paid, the “non-reproducible information” already stored in the memory 29 is “N-1 times to allow reproduction”. Information "is rewritten (step S32). Then, the access control circuit 28A sends a control signal for turning on decryption to the decryption circuit 25. Therefore, the encrypted video signal recorded on the magnetic tape 40 is decrypted and reproduced (step S30).
[0073]
Next, a case where the video software is rented with a viewing time limit by paying a fee at the time of reproduction will be described.
[0074]
If the information from the memory 29 is non-reproducible information, the access control circuit 28A is connected to the broadcast station 101 (step S33). Here, if you want to rent video software with a viewing deadline, you will be paid a rental fee. It is checked whether or not the purchase fee of the video software has been paid (step S34). If the fee has not been paid, it is checked whether or not to rent with a limited number of viewing times (step S36), and the viewing fee for N times is determined. If it has not been paid, it is checked whether or not the rental fee up to the deadline Y has been paid (step S37).
[0075]
If the rental fee up to the time limit Y has been paid, the “non-reproducible information” already stored in the memory 29 is rewritten to “reproducible information up to the time limit Y” (step S38). Then, the access control circuit 28A sends a control signal for turning on decryption to the decryption circuit 25. Therefore, the encrypted video signal recorded on the magnetic tape 40 is decrypted and reproduced (step S30).
[0076]
g. Modified example
In the above-described embodiment, the cassette 104A with memory is used and the access condition is stored in the memory 29 of the cassette 104A with memory. However, the access condition memory is limited to the memory 29 of the cassette 104A with memory. It is not something. As shown in FIG. 5, for example, the subcode area of the magnetic tape 40 of the cassette 104B may be used as a memory for storing access conditions.
[0077]
In the above-described embodiment, the encryption circuit 22 and the decryption circuit 25 are provided, and access control is performed by performing encryption / decryption. Instead of using such encryption, FIG. As shown, the operation of the descrambler 21C may be controlled by the access control circuit 28C, and access may be controlled without or without solving the descrambling.
[0078]
Further, as shown in FIG. 7, for example, the subcode area of the magnetic tape 40 of the cassette 104C is used as a memory for storing access conditions, and the operation of the descrambler 21C is controlled by the access control circuit 28C to solve the descrambling / You may make it control access without solving.
[0079]
In the above example, information from the broadcasting station is sent via a line, but such information may be sent as additional information for television broadcasting. Also, an encryption key may be sent together with the information.
[0080]
In the above example, the public line is used to enable data communication between the broadcasting station and each home receiving system terminal, and video software orders and additional information are sent as data. It is also possible to place an order for video software directly using the telephone, have the additional information returned in response, and input the additional information to each receiving system.
[0081]
The present invention can be similarly applied to a system in which video signal transmission and data transmission are performed using a line.
[0082]
【The invention's effect】
  According to this invention,Since the time information from the information provider is received and the current time information of the clock is set by the received time information, unauthorized viewing can be prevented by operating the clock time illegally.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an outline of a digital television system using a satellite to which the present invention can be applied.
FIG. 2 is a block diagram used to explain an embodiment of the present invention.
FIG. 3 is a flowchart used to explain an embodiment of the present invention.
FIG. 4 is a flowchart used to explain an embodiment of the present invention.
FIG. 5 is a block diagram used for explaining another embodiment of the present invention.
FIG. 6 is a block diagram used for explaining another embodiment of the present invention.
FIG. 7 is a block diagram used for explaining another embodiment of the present invention.
[Explanation of symbols]
22 Encryption circuit
25 Cryptanalysis circuit

Claims (7)

A reproduction control method for controlling reproduction of an information signal which is encrypted and recorded on a recording medium,
The time information generated and transmitted by the provider of the information signal is received,
The received time information is supplied to the watch,
Based on the additional information generated and transmitted by the provider of the information signal, reproduction condition information indicating a reproduction period or period of the recorded information signal is recorded on a recording medium,
Based on the reproduction condition information and the current time information from the clock, the reproduction of the recorded information signal from the recording medium and the release of the encryption applied to the reproduced information signal are controlled. A reproduction control method characterized by the above. 2. The reproduction control method according to claim 1 , wherein the information signal is a compressed signal, and the decrypted information signal is compressed and decrypted. 2. The reproduction control according to claim 1 , wherein the reproduction condition information is generated based on the additional information transmitted by communication between a receiving device and the information provider, and recorded on the recording medium. Method. The reproduction control method according to claim 1 , wherein the reproduction condition information is rewritable information on the recording medium. An information signal transmission / reception method comprising:
On the sending side,
Transmit information signals to the receiver,
Transmit time information generated by the provider of the information signal,
Is generated by the provider of the information signal, and transmits the reproduction condition information indicating a reproduction time limit or period of the information signal in the receiver as additional information to be used for recording on a recording medium,
On the receiving side,
Receive the transmitted time information,
The received time information is supplied to the watch,
Receiving the transmitted information signal,
Record the received information signal on a recording medium with encryption,
Receiving the transmitted additional information,
Recording reproduction condition information on the recording medium based on the received additional information,
Based on the reproduction condition information and the current time information from the clock, the reproduction of the recorded information signal from the recording medium and the release of the encryption applied to the reproduced information signal are controlled. A transmission / reception method characterized by the above. 6. The transmission / reception method according to claim 5 , wherein the information signal and the additional information are transmitted through the same transmission medium. Transmitting and receiving method according to claim 5, wherein the information signal and the additional information, characterized in that transmitted via different transmission media.

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