JP2016165060A - Electronic apparatus and decryption program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic apparatus that can easily decrypt, only for a predetermined time, a content which has been encrypted.SOLUTION: An electronic apparatus includes a tuner 1, a CAS client 2, and a renderer 3. The CAS client 2 has a control unit 21, a timer 22, and a decryption key generation unit 23. Since the timer 22 and decryption key generation unit 23 are provided in the CAS client 2, it is unnecessary to feed back a count time from the renderer 3 to the CAS client 2, thus enabling preview with a simple processing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electronic device and a decryption program that decrypt an encrypted content signal.

  It is widely performed to distribute content signals from broadcast stations and reproduce them with electronic devices such as smartphones, personal computers, and televisions. In the case of pay broadcasting, the content distributor encrypts and distributes the content signal in order to ensure profits from the distribution. In this case, only a specific user who has a contract with the content distributor can decode the content signal and view the content.

  Even when the content signal is encrypted and distributed, the viewer may not be allowed to view the content for a short period of time in order to increase the number of subscribers. Such short-time playback of content is also called a preview.

JP 2011-216951 A

  When previewing, it is necessary to decrypt the encrypted content for a predetermined preview time. Therefore, the decoding time must be properly managed. If this management requires complicated processing, the processing load on the electronic device increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electronic device and a decryption program for decrypting a content signal encrypted for a predetermined time by simple processing.

According to one aspect of the present invention, an electronic device that decrypts an encrypted content signal using a decryption key, the decryption key transmitting unit that transmits the decryption key, the encrypted content signal, and An electronic device is provided that includes a decryption key receiving unit that receives the decryption key and decrypts the content signal using the decryption key. In this electronic device, the decryption key transmission unit starts timing in synchronization with the transmission start of the decryption key, and when the time reaches a preset time for the content signal, the decryption key Stop sending
According to such a configuration, since the time is measured in the decryption key transmission unit, the transmission time of the decryption key can be grasped by the decryption key transmission unit. Therefore, the processing of the electronic device can be simplified.

In addition, when the decryption key transmission is completed before the timed time reaches the set time, the decryption key transmission unit obtains transmission time information related to the transmitted time of the decryption key based on the timed time. And when the content signal is received again by the decryption key receiving unit, based on the transmission time information, the decryption key is transmitted until the total transmission time of the decryption key reaches the set time, When the total transmission time of the decryption key reaches the set time, the transmission of the decryption key may be stopped.
According to such a configuration, since the transmission time information related to the transmission time of the decryption key is stored, it is possible to divide the set time predetermined for the content signal into a plurality of times.

  As a specific configuration example, the decryption key transmission unit includes a time measurement unit that starts timing substantially simultaneously with the start of transmission of the decryption key, and a decryption key generation unit that generates the decryption key and transmits the decryption key to the decryption key reception unit And when the time-measurement time of the said time-measurement part reaches the said setting time, it may have a decoding key production | generation part which stops transmission of the said decoding key.

According to an aspect of the present invention, there is provided an electronic device that decrypts an encrypted content signal using a decryption key, wherein the decryption key and a set time predetermined for the content signal are set. A decryption key transmitter for transmitting the encrypted content signal, the decryption key, and the time information, and decrypting the content signal using the decryption key; Are provided. In this electronic device, the decryption key receiving unit starts timing in synchronization with the reception start of the decryption key, and stops the decryption of the content signal when the measured time reaches the set time.
According to such a configuration, the decryption key receiving unit measures the time after receiving the set time. Therefore, the processing of the electronic device can be simplified.

Further, when the decryption key receiving unit finishes decrypting the content signal before the timed time reaches the set time, the decrypted time information on the time when the content signal has been decrypted based on the timed time Is transmitted to the decryption key transmitting unit, and when the content signal is received again by the decryption key receiving unit, the decryption key transmitting unit transmits the decrypted time information to the decryption key receiving unit. When the key receiving unit receives the content signal again, the key receiving unit decrypts the content signal based on the decrypted time information until the total decoding time of the content signal reaches the set time, and the total decoding of the content signal When the time reaches the set time, the decoding of the content signal may be stopped.
According to such a configuration, since the decoded time information relating to the decoded time of the content signal is stored, it is possible to decode the set time predetermined for the content signal in a plurality of times.

  As a specific configuration example, the decryption key receiving unit is a timing unit that starts timing substantially simultaneously with the reception start of the decryption key, and a decryption unit that decrypts the content signal using the decryption key, And a decoding unit that stops decoding the content signal when the time measured by the time measuring unit reaches the set time.

  The electronic device extracts the encrypted content signal from the input signal and supplies the encrypted content signal to the decryption key reception unit, and extracts control information indicating the set time from the input signal and supplies the control information to the decryption key transmission unit A tuner may be provided.

  According to another aspect of the present invention, there is provided a decryption key transmission unit that transmits a decryption key for decrypting an encrypted content signal to the decryption unit, and counts time in synchronization with the transmission start of the decryption key. An electronic device is provided that includes a decryption key transmission unit that stops transmission of the decryption key when the measured time reaches a preset time for the content signal.

  According to one aspect of the present invention, an encrypted content signal, a decryption key for decrypting the encrypted content signal, and a time indicating a preset time for the content signal A decryption key receiving unit that receives information and decrypts the content signal using the decryption key, and starts timing in synchronization with the reception start of the decryption key, and when the measured time reaches the set time An electronic device including a decryption key receiving unit that stops decryption of the content signal is provided.

  According to one aspect of the present invention, there is provided a decoding program for causing a computer to function as each unit of the electronic device.

  According to the present invention, the encrypted content can be decrypted for a predetermined time by a simple process.

1 is a block diagram showing a schematic configuration of an electronic device according to a first embodiment of the present invention. 3 is a flowchart showing an example of processing operation when previewing is performed in the electronic apparatus of FIG. 1. 9 is a flowchart illustrating an example of processing operation of an electronic device according to a second embodiment. The block diagram which shows schematic structure of the electronic device which concerns on the 3rd Embodiment of this invention. 5 is a flowchart showing an example of processing operation when previewing is performed in the electronic apparatus of FIG. 4.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of an electronic apparatus according to the first embodiment of the present invention. The electronic device in FIG. 1 is, for example, a smartphone, a tablet terminal, or a personal computer.

  The electronic device includes a tuner 1, a CAS (Conditional Access System) client 2, and a renderer 3. Either or one of the CAS client 2 and the renderer 3 may be implemented by hardware, or at least a part of these may be configured by software. When configured with software, the processor (not shown) of the electronic device executes the decryption program (not shown) recorded in the nonvolatile memory, thereby realizing the functions (at least part of) of the CAS client 2 and the renderer 3. You may make it do.

  An input signal such as a broadcast wave signal transmitted from a broadcasting station or a signal transmitted by communication means is input to the electronic device. The input signal here includes one or a plurality of encrypted content signals, and a control signal is added to each content signal.

  The tuner 1 receives an input signal, selects a channel according to a user setting, and extracts one encrypted content signal and control signal set from the input signal. The encrypted content signal is supplied to the renderer 3 and the control signal is supplied to the CAS client 2.

  The content signal includes a video signal and an audio signal. Since the content signal is encrypted, a decryption key (described later) is required to decrypt and reproduce the content signal. Note that the content signal may include only one of the video signal and the audio signal.

  The control signal includes information for determining whether or not the encrypted content signal may be decrypted, that is, information for determining whether or not a decryption key can be generated. Some content signals can be “previewed” in which content is played back only for a certain period of time, even if no content playback contract is signed with the user. In this case, the control signal further includes information indicating that the preview is possible and information on a time during which the content signal can be reproduced as a preview (also simply referred to as a preview time or a set time). The preview time is predetermined by the content distributor for the content signal, for example.

  The CAS client 2 includes a control unit 21, a timer (timer unit) 22, and a decryption key generation unit 23.

  The control unit 21 uses the control information extracted from the input signal to determine whether to generate a decryption key based on the user's contract status and content usage conditions. The user's contract status and content usage conditions are stored in the CAS client 2 in advance.

  When a contract for reproducing the content signal supplied from the tuner 1 is made, the control unit 21 instructs the decryption key generation unit 23 to generate a decryption key and transmit it to the renderer 3. As a result, the content signal is decoded and the user can view the content.

  When a contract for reproducing the content signal supplied from the tuner 1 is not concluded, the control unit 21 does not instruct generation of a decryption key in principle. Therefore, the content signal is not decoded and the user cannot view the content.

  On the other hand, even when the contract for reproducing the content signal supplied from the tuner 1 is not concluded, the control signal may include information indicating that the preview is possible. In this case, the control unit 21 instructs the decryption key generation unit 23 to generate a decryption key and transmit it to the renderer 3. Furthermore, the control unit 21 sets the preview time in the timer 22 and instructs the timer 22 to start timing.

  The timer 22 starts measuring time according to an instruction from the control unit 21. In the present embodiment, the time count by the timer 22 shows an example in which the preview time is counted down as an initial value and timed until the count value becomes zero.

  The decryption key generation unit 23 starts generation of a decryption key and transmission of the decryption key to the renderer 3 (payout) in response to an instruction from the control unit 21. Thereafter, the decryption key generation unit 23 stops generating the decryption key according to the time measured by the timer 22. More specifically, the decryption key generation unit 23 confirms the time measured by the timer 22, and if the time measured has not reached the preview time, that is, if the count value of the timer 22 has not reached 0, it is periodically Continue sending the decryption key (for example, every second). On the other hand, when the timekeeping time reaches the preview time, that is, when the count value of the timer 22 reaches 0, the decryption key generation unit 23 stops generating the decryption key.

  As described above, the CAS client 2 operates as a decryption key transmission unit that transmits a decryption key to the renderer 3 for a predetermined preview time.

  On the other hand, the renderer 3 is a decryption key receiving unit, and includes a decryption unit 31 and a codec unit 32. The decryption unit 31 receives the decryption key from the CAS client 2 and decrypts the encrypted content signal using the decryption key. Decryption here means releasing the encryption. Further, the codec unit 32 converts the decoded content signal into a video signal and an audio signal. The video signal and the audio signal may be supplied to a resident (not shown). As described above, the renderer 3 can decrypt the content signal while receiving the decryption key, but cannot decrypt the content signal when the decryption key is not transmitted from the CAS client 2.

  FIG. 2 is a flowchart illustrating an example of processing operation when previewing is performed in the electronic apparatus of FIG. In the figure, for the sake of convenience, the steps S1 to S8 are illustrated in the order of steps. However, the processes are not necessarily performed in this order, and may be appropriately replaced or a plurality of processes may be performed simultaneously.

  Control information about the content signal supplied from the tuner 1 to the renderer 3 is input to the control unit 21. If the control unit 21 determines that the content signal can be previewed based on the control information (YES in step S1), the control unit 21 sets the preview time included in the control information in the timer 22 and starts timing. (Step S2). Further, the control unit 21 instructs the decryption key generation unit 23 to generate a decryption key and start transmission to the renderer 3 (step S3).

  In response to such an instruction from the control unit 21, the timer 22 starts measuring time and counts down using the set preview time as an initial value (step S4). On the other hand, the decryption key generation unit 23 generates a decryption key and starts transmitting the decryption key to the renderer 3 (step S5). As a result, the timer 22 starts timing in synchronization with the start of transmission of the decryption key, that is, almost simultaneously.

  When receiving the decryption key, the decryption unit 31 of the renderer 3 decrypts the encrypted content signal using the decryption key. Further, the codec unit 32 converts the decoded content signal into a video signal and an audio signal. Then, the renderer 3 outputs a video signal and an audio signal (step S6), and the user can view the content.

  On the other hand, the decryption key generation unit 23 confirms the time measured by the timer 22 while transmitting the decryption key. (Step S7). If the measured time has not reached the preview time, that is, if the count value of the timer 22 has not reached 0 (NO in step S7), the decryption key generation unit 23 continues to transmit the decryption key to the renderer 3 (step S5). ). Thereafter, as long as the same content signal is supplied from the tuner 1, steps S5 to S7 are repeated until the measured time reaches the preview time.

  When the measured time reaches the preview time, that is, when the count value of the timer 22 reaches 0 (YES in step S7), the decryption key generation unit 23 stops transmitting the decryption key to the renderer 3 (step S8). As described above, when it is determined that the transmission time of the decryption key has reached the preview time based on the measured time, the decryption key transmission from the decryption key generation unit 23 to the renderer 3 is stopped. As a result, the renderer 3 cannot decrypt the encrypted content signal, and the preview ends. When the preview is completed after the preview time has elapsed, the control unit 21 may store information for specifying the content for which the preview has been completed. This makes it impossible to preview even if the same content signal is received later.

  As described above, the electronic device can decrypt the encrypted content signal. As can be seen from the above description, the time that can be decrypted is the time during which the decryption key generation unit 23 is transmitting the decryption key to the renderer 3, which is equal to the preview time.

  When the timer 22 starts counting simultaneously with the start of transmission of the decryption key, in step S7, transmission of the transmission key may be stopped when the measured time reaches the preview time. On the other hand, there may be a time lag between the transmission start of the decryption key and the time measurement start by the timer 22. In such a case, in step S7, considering the time lag, transmission of the transmission key may be stopped when the transmission time of the decryption key reaches the preview time.

  Incidentally, it is conceivable that the timer 22 is provided not in the CAS client 2 but in the renderer 3. However, in such a configuration, it is the CAS client 2 that knows the preview time, while the renderer 3 measures the decoded time. Therefore, in order for the decryption key generation unit 23 in the CAS client 2 to transmit the decryption key for the preview time, the timekeeping time must be fed back from the renderer 3 to the CAS client 2. When such feedback processing is performed, the configuration and processing of the renderer 3 must be complicated.

  On the other hand, in this embodiment, a timer 22 and a decryption key generation unit 23 are provided in the CAS client 2. Therefore, it is not necessary to feed back the timekeeping time from the renderer 3 to the CAS client 2, and a preview can be realized with a simple configuration and processing. In addition, since it is not necessary to provide a timer in the renderer 3, the mounting of the renderer 3 is simplified.

(Second Embodiment)
The second embodiment to be described below is a modification of the first embodiment. A process in which a preview is performed for a time shorter than a predetermined preview time, for example, a content signal for which a 10-second preview is permitted is shown. The present invention relates to processing when decoding is performed for 7 seconds. Hereinafter, a description will be given focusing on differences from the first embodiment.

  The configuration of the electronic device itself is almost the same as that shown in FIG. However, the control unit 21 stores the remaining preview time when the preview is completed during the preview because the content signal selected by the user is switched. In the above numerical example, when previewing for the first time, the timer 22 counts down using “10 seconds” as an initial value. When previewing only “7 seconds”, in other words, when previewing ends when the count value of the timer 22 is “3 seconds”, the control unit 21 determines that the remaining preview time of the content signal is “3 seconds”. I remember that. Thereafter, when previewing the same content, the timer 22 counts down using “3 seconds” as an initial value.

  FIG. 3 is a flowchart illustrating an example of a processing operation of the electronic device according to the second embodiment. In the figure, the same reference numerals are assigned to the processing operations common to FIG. In order to make the description easy to understand, the description starts from step S22 in the figure, and the description of the processing operations common to the first embodiment is simplified.

  While the renderer 3 is decrypting the content signal using the decryption key, the content signal selected by the tuner 1 is not switched, and the same content signal continues to be supplied to the renderer 3, and the control signal related to this content signal is CAS. If it continues to be supplied to the client 2 (YES in step S22), the content signal decoding process shown in steps S5 to S7 is repeated until the measured time reaches the preview time.

If the same content signal is not supplied before the decryption time of the content signal, in other words, the transmission time of the decryption key (that is, the time measured by the timer 22) reaches the preview time (NO in step S22), the control unit 21 The decryption key generation unit 23 is instructed to stop transmitting the decryption key (step S23). Further, the control unit 21 stores the count value of the timer 22, that is, “preview time—time when the decryption key is transmitted to the renderer 3” as the remaining preview time (transmission time information) (step S24). As the decryption key transmission stops, the content signal decryption process also stops.
Thus, the preview process ends.

  On the other hand, when a previewable content signal is received (YES in step S1), the control unit 21 determines whether or not the content signal has already been previewed, more specifically, the remaining preview time of the content signal. Is stored (step S21).

  If the preview has not been completed (NO in step S21), the control unit 21 sets a preview time based on the control signal in the timer 22 (step S2a), similarly to step S2 in FIG. On the other hand, when the preview has already been completed and the remaining preview time is stored, the control unit 21 sets the remaining preview time in the timer 22 (step S2b).

  The subsequent steps S3 to S6 are as already described. In step S7, it is determined based on the remaining preview time set in step S2b whether or not the count value of the timer 22 has reached 0, that is, whether or not the total of the measured time has reached the preview time. The As a result, the encrypted content signal is decrypted only for the preview time at one time or divided into a plurality of times.

  As described above, in the second embodiment, when the preview is terminated during the preview, the remaining previewable time is stored. Therefore, the content signal can be decoded only for the preview time in a plurality of times. For the user, it is possible to view the content continuously for the preview time, and it is possible to view the content in small pieces, which improves convenience.

  In the present embodiment, the control unit 21 stores the remaining preview time. However, the timer 22 itself may store the preview time. In this case, the timer 22 may measure the time based on the preview time set from the control unit 21 if the remaining preview time is stored. Moreover, although the example which memorize | stores the remaining preview time was shown in this embodiment, the control part 21 may calculate the remaining preview time, memorize | stored already decoded time. It goes without saying that various other modified examples can be considered.

(Third embodiment)
In the first and second embodiments described above, the timer 22 is provided in the CAS client 2 to control the time during which the CAS client 2 actively transmits the decryption key. On the other hand, in the third embodiment described below, a timer is provided in the renderer, and the time for decoding the content signal in the renderer is controlled.

  FIG. 4 is a block diagram showing a schematic configuration of an electronic apparatus according to the third embodiment of the present invention. Portions common to those in FIG. 1 are denoted by common reference numerals, and hereinafter, differences from FIG. 1 will be mainly described.

  The CAS client 2a of this embodiment includes a control unit 21a and a decryption key generation unit 23a. When the control unit 21a determines that preview is possible based on the control signal, the control unit 21a instructs the decryption key generation unit 23a to generate a decryption key and transmit the decryption key to the renderer 3a, and also displays preview time information indicating the preview time as the renderer 3a. To supply. The decryption key generation unit 23a generates a decryption key in response to an instruction from the control unit 21a, and transmits the decryption key to the renderer 3a. In this way, the CAS client 2a operates as a decryption key transmission unit that transmits a decryption key and preview time information.

  The renderer 3a according to the present embodiment includes a timer (timer) 33 in addition to the decoder 31a and the codec 32. When the timer 33 receives preview time information from the control unit 21a of the CAS client 2a, the timer 33 starts measuring time. That is, the timer 33 counts down using the preview time indicated by the preview time information as an initial value. Upon receiving the decryption key, the decryption unit 31a receives the encrypted content signal on the condition that the time measured by the timer 33 has not reached the preview time, that is, the count value of the timer 33 has not reached 0. While decoding, it converts into a video signal and an audio signal. Thus, the renderer 3a operates as a decryption key receiving unit that receives the decryption key and decrypts the content signal encrypted for the preview time using the decryption key.

  FIG. 5 is a flowchart illustrating an example of a processing operation when previewing is performed in the electronic apparatus of FIG. Processing operations common to those in FIG. 2 are denoted by common reference numerals, and differences from FIG. 2 will be mainly described.

  When a previewable content signal is received (YES in step S1), the control unit 21a transmits preview time information indicating the preview time to the timer 33 of the renderer 3a (step S31). The generation unit 23a is instructed to generate a decryption key and start transmission to the renderer 3a (step S3). Thereby, the decryption key generation unit 23a starts the decryption key transmission to the renderer 3a (step S5). Thereafter, the decryption key generation unit 23a continues to transmit the decryption key to the renderer 3a while receiving the same content signal regardless of the time measured by the timer 33.

  On the other hand, when receiving the preview time information, the timer 33 of the renderer 3a starts measuring time and counts down using the preview time as an initial value (step S32). When receiving the decryption key, the decryption unit 31a decrypts the encrypted content signal using the decryption key. Further, the codec unit 32 converts the decoded content signal into a video signal and an audio signal (step S6). As described above, the start of timing of the timer 33 is synchronized with the reception of the decryption key by the decryption unit 31a or the start of the decryption process.

  In addition, the decoding unit 31a checks the time measured by the timer 33 while decoding the content signal (step S7). If the measured time has not reached the preview time, that is, if the count value has not reached 0 (NO in step S7), the decoding unit 31a continues to decode the content signal (step S6). On the other hand, when the measured time reaches the preview time, that is, when the count value reaches 0 (YES in step S7), the decryption unit 31a continues to receive the decryption key, but stops decrypting the content signal ( Step S33). In this way, when it is determined that the decoding time has reached the preview time based on the time measured by the timer 33, the content signal decoding process stops.

  If the timer 33 starts counting simultaneously with the reception of the decryption key, the decryption process may be stopped at the time when the measured time reaches the preview time in step S7. On the other hand, there may be a time lag between the reception start of the decryption key and the time measurement start by the timer 33. In such a case, in step S7, the decoding process may be stopped when the decoding process time reaches the preview time in consideration of the time lag.

  As described above, in the third embodiment, the timer 33 is provided in the renderer 3a, and the preview time information is transmitted to the renderer 3a. Then, the decoding time is controlled in the renderer 3a based on the time measured by the timer 33. Therefore, a feedback process from the renderer 3a to the CAS client 2a is unnecessary, and a preview can be easily realized.

  In the present embodiment, the decryption unit 31a continues to receive the decryption key even after the preview time has elapsed. Therefore, if the renderer 3a is altered, the content may be decrypted by the decryption unit 31a even after the preview time has elapsed. Therefore, in this embodiment, it is desirable to have a strong structure so that the renderer 3a is not altered.

  Further, as a modification of the third embodiment, the same processing as in the second embodiment may be performed. That is, when the content signal is decoded halfway through the preview time, the remaining preview time, that is, “preview time−decoded time” is transmitted from the renderer 3a to the CAS client 2a as decoded time information. And stored in the control unit 21a. Next, when the same content is received next, preview time information indicating the remaining preview time may be transmitted to the renderer 3a so that the preview can be performed only for the remaining preview time. Alternatively, the remaining preview time may be stored in the renderer 3a.

  In each of the above embodiments, an example in which a tuner, a CAS client, and a renderer are provided in one electronic device has been described. However, some of these may be provided in a separate device or omitted. Also good. For example, the CAS client may be provided in the first electronic device, and the renderer may be provided in the second electronic device.

  At least a part of each part of the electronic device described in the above-described embodiment may be configured by hardware or software. When configured by software, a program that realizes at least a part of the functions of each unit of the electronic device may be stored in a recording medium such as a flexible disk or a CD-ROM, and read and executed by a computer. The recording medium is not limited to a removable medium such as a magnetic disk or an optical disk, but may be a fixed recording medium such as a hard disk device or a memory.

  Further, a program that realizes at least a part of functions of each unit of the electronic device may be distributed via a communication line (including wireless communication) such as the Internet. Further, the program may be distributed in a state where the program is encrypted, modulated or compressed, and stored in a recording medium via a wired line such as the Internet or a wireless line.

  Based on the above description, those skilled in the art may be able to conceive additional effects and various modifications of the present invention, but the aspects of the present invention are not limited to the individual embodiments described above. Absent. Various additions, modifications, and partial deletions can be made without departing from the concept and spirit of the present invention derived from the contents defined in the claims and equivalents thereof.

1 tuner 2, 2a CAS client 21, 21a control unit 22 timer 23, 23a decryption key generation unit 3, 3a renderer 33 timer 31, 31a decryption unit 32 codec unit

Claims (10)

An electronic device that decrypts an encrypted content signal using a decryption key,
A decryption key transmitter for transmitting the decryption key;
A decryption key receiving unit that receives the encrypted content signal and the decryption key, and decrypts the content signal using the decryption key;
The decryption key transmission unit starts timing in synchronization with the transmission start of the decryption key, and stops the transmission of the decryption key when the measured time reaches a preset time for the content signal. An electronic device characterized by that. The decryption key transmitter
If the transmission of the decryption key is completed before the timed time reaches the set time, based on the timed time, transmission time information related to the transmitted time of the decryption key is stored,
When the content signal is received again by the decryption key receiving unit, the decryption key is transmitted until the total transmission time of the decryption key reaches the set time based on the transmission time information. The electronic device according to claim 1, wherein when the total transmission time reaches the set time, transmission of the decryption key is stopped. The decryption key transmitter
A timing unit that starts timing almost simultaneously with the start of transmission of the decryption key;
A decryption key generating unit that generates the decryption key and transmits the decryption key to the decryption key receiving unit, and stops the transmission of the decryption key when the time measured by the time measuring unit reaches the set time; The electronic apparatus according to claim 1, further comprising: An electronic device that decrypts an encrypted content signal using a decryption key,
A decryption key transmitter for transmitting the decryption key and time information indicating a preset time for the content signal;
A decryption key receiving unit that receives the encrypted content signal, the decryption key, and the time information, and decrypts the content signal using the decryption key;
The electronic device, wherein the decryption key receiving unit starts timing in synchronization with the reception start of the decryption key, and stops the decryption of the content signal when the measured time reaches the set time. When the decryption key receiving unit finishes decrypting the content signal before the timed time reaches the set time, based on the timed time, the decryption key receiving unit obtains the decrypted time information related to the decrypted time of the content signal. Sent to the decryption key transmitter,
The decryption key transmitting unit stores the received decrypted time information, and when the content signal is received again by the decryption key receiving unit, transmits the decrypted time information to the decryption key receiving unit. ,
When receiving the content signal again, the decryption key receiving unit decrypts the content signal based on the decrypted time information until the total decryption time of the content signal reaches the set time, 5. The electronic apparatus according to claim 4, wherein when the total decoding time reaches the set time, the decoding of the content signal is stopped. The decryption key receiving unit
A timing unit that starts timing substantially simultaneously with the reception of the decryption key;
A decrypting unit for decrypting the content signal using the decryption key, the decrypting unit stopping the decryption of the content signal when the time measured by the time measuring unit reaches the set time; The electronic device according to claim 4 or 5.   A tuner that extracts the encrypted content signal from the input signal and supplies the encrypted content signal to the decryption key reception unit, and extracts control information indicating the set time from the input signal and supplies the control information to the decryption key transmission unit; The electronic device according to claim 1, wherein the electronic device is a device.   A decryption key transmitting unit that transmits a decryption key for decrypting the encrypted content signal to the decryption unit, and starts timing in synchronization with the start of transmission of the decryption key, and the measured time is added to the content signal. An electronic apparatus comprising: a decryption key transmission unit that stops transmission of the decryption key when a predetermined set time is reached.   Receiving an encrypted content signal, a decryption key for decrypting the encrypted content signal, and time information indicating a preset time for the content signal, and using the decryption key A decryption key receiving unit for decrypting the content signal, wherein the decryption key starts timing in synchronization with the reception start of the decryption key, and stops the decryption of the content signal when the measured time reaches the set time An electronic device comprising a receiving unit.   A decoding program for causing a computer to function as each unit of the electronic device according to any one of claims 1 to 9.

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