Patent Publication Number: US-2007098165-A1

Title: Viewing control apparatus, viewing control program and secure module

Description:
TECHNICAL FIELD  
      The present invention relates to a viewing control apparatus that controls viewing of broadcast contents or stored contents, viewing control program, secure module and storage medium which records contents or the like, and more particularly to allowing viewing of contents on condition of viewing an advertisement.  
     BACKGROUND ART  
      Conventionally, digital contents are delivered to users by means of broadcasting or recorded in storage media such as DVD and prices for contents are collected from users in forms of purchase cost of the storage media or broadcasting fees, from an advertiser for an advertisement attached to the contents or based on a billing scheme (pay per view: PPV) or the like applied when the contents are viewed.  
      In the case of charged broadcasting paid by users as a price for contents, contents are encrypted (scrambled) using an encryption key (scramble key) Ks and then broadcasted and program information (ECM: Entitlement Control Message) including information about the scramble key Ks and a program viewing condition together with the contents is encrypted using a work key Kw and then broadcasted. This scramble key Ks is updated every several seconds.  
      On the other hand, a reception apparatus of users who have signed a viewing contract receives a work key Kw for decrypting the ECM and individual information including information about contract terms (EMM: Entitlement Management Message) from broadcasting and this EMM is stored in an IC card inserted in the reception apparatus.  
      When users view broadcast contents, ECM received by the reception apparatus is decrypted by Kw and it is decided whether or not EMM contract terms satisfy the program viewing condition included in ECM. When they satisfy the condition or when program purchasing processing is performed under PPV, Ks included in ECM is decrypted using the Kw and the received contents are descrambled using this Ks.  
      Furthermore, when contents are delivered recorded in a storage medium, a scheme that encrypts a contents and records them in a storage medium to protect copyrights and delivers the storage medium and contents decrypting key to the contents purchaser is designed.  
      On the other hand, when a price for broadcast contents is collected from an advertiser, the contents are broadcasted together with an advertisement without any scrambling. A viewer who receives the contents can view the contents free of charge in exchange for viewing the advertisement.  
      However, there is a tendency in recent years that contents delivered by means of broadcasting are stored in a storage device first and then viewed, and therefore it is often the case that even when contents are broadcasted accompanied by an advertisement, viewers skip the advertisement and reproduce and view only contents. Such situation counteracts an effect of an advertisement using a broadcast medium.  
      Patent Document 1 (Unexamined Japanese Patent Publication No. 2002-157516) provides a method of delivering advertisement information designed to promote a viewing of broadcast and stored advertisements. This method allows users to rent a broadcasting reception terminal at low cost by viewing advertisements. When users reproduce and view an advertisement which has been broadcasted and stored, a history thereof is recorded in a hard disk and notified to an advertisement issuing site and a rental fee for the next month is discounted according to the time of reproducing and viewing the advertisement.  
      The scheme of collecting a price for broadcast contents from an advertiser of advertisement provides a merit for the advertiser in that the advertisement becomes widespread among users and also provides a merit for users that users can view the contents free of charge. However, the mode of viewing in recent years in which broadcast contents are stored once and reproduced at a desired time allows users to skip advertisements and reproduce only contents, which is likely to lessen the effects of advertisements using broadcasting, cause withdrawal of advertisers from broadcasting and make more difficult for deliberation of contents based on advertisement as described above.  
      Furthermore, even some measure is taken to promote viewing of stored advertisements, viewing an old advertisement broadcasted and stored in the past does not meet the advertiser&#39;s expectation.  
      On the other hand, the method of billing contents when they are stored or viewed requires collecting fees from individual viewers, which results in a problem of requiring the cost for collecting the fees. Furthermore, since contents are charged before they are viewed, viewers have a tendency to hesitate to purchase the contents without checking their contents, which results in a problem that substantial income cannot be expected. Furthermore, this billing method may cause companies to lose their advertising places.  
     DISCLOSURE OF INVENTION  
      The present invention solves the above described conventional problems and it is an object of the present invention to provide a viewing control apparatus for allowing a viewer to view contents on condition of viewing an advertisement, viewing control program, secure module and a recording medium or the like that records the contents.  
      In order to attain the above described object, an aspect of the present invention is a viewing control apparatus constructed so as to store contents identification information and viewing condition information indicating a viewing expiration date of the contents in a processing module, when an advertisement associated with viewing condition update information for updating the viewing condition information is reproduced, update the viewing condition information stored in the processing module through an updating section based on the viewing condition update information, and control the reproduction of the contents based on the viewing condition information. Note that the present specification will refer to various apparatuses involved in contents viewing control such as device, secure module, time correction site, advertisement issuing site, individually or a combination thereof as a “viewing control apparatus.”  
      Furthermore, another aspect of the present invention is a viewing control program constructed in such a way that a computer stores contents identification information and viewing condition information indicating a viewing expiration date of the contents, when an advertisement associated with viewing condition update information for updating the viewing condition information is reproduced, updates stored viewing condition information based on the viewing condition update information, and controls the reproduction of the contents based on the viewing condition information.  
      Furthermore, in a further aspect of the present invention, a secure module stores viewing condition information of contents indicating encrypted contents to be viewed and an expiration date until which the encrypted contents can be viewed and decrypts the encrypted contents based on the expiration date indicated by the viewing condition information to reproduce. And the secure module is configured to update the viewing condition information based on the viewing condition update information when an advertisement associated with viewing condition update information updating an expiration date of the encrypted contents indicated by the viewing condition information and to make it possible to view the encrypted contents indicated by the viewing condition update information. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  illustrates a configuration example of a viewing control apparatus according to a first embodiment of the present invention;  
       FIG. 2  illustrates a configuration example of an advertisement;  
       FIG. 3  illustrates a configuration example of EMM update request information;  
       FIG. 4  illustrates a configuration example of an EMM before a viewer views an advertisement;  
       FIG. 5  is a flow chart illustrating an example of advertisement reproduction operation by the viewing control apparatus;  
       FIG. 6  illustrates a configuration example of an EMM after a viewer views an advertisement;  
       FIG. 7  is a flow chart illustrating an example of encrypted contents reproduction operation by the viewing control apparatus;  
       FIG. 8  illustrates a configuration example of a viewing control apparatus according to a second embodiment of the present invention;  
       FIG. 9  is a flow chart illustrating operation of the viewing control apparatus according to the second embodiment of the present invention;  
       FIG. 10  illustrates a configuration example of a viewing control apparatus according to a third embodiment of the present invention;  
       FIG. 11  is a flow chart illustrating operation of the viewing control apparatus according to the third embodiment of the present invention;  
       FIG. 12  illustrates a configuration example of a viewing control apparatus according to a fourth embodiment of the present invention;  
       FIG. 13  is a flow chart illustrating operation of the viewing control apparatus according to the fourth embodiment of the present invention;  
       FIG. 14  illustrates a configuration example of a viewing control apparatus according to a fifth embodiment of the present invention;  
       FIG. 15  illustrates a configuration example of a viewing control apparatus according to a sixth embodiment of the present invention;  
       FIG. 16  illustrates a configuration example of a viewing control apparatus according to a seventh embodiment of the present invention;  
       FIG. 17  illustrates a configuration example of a viewing control apparatus according to an eighth embodiment of the present invention;  
       FIG. 18  illustrates a configuration example of a viewing control apparatus according to a ninth embodiment of the present invention;  
       FIG. 19  illustrates a configuration example of a viewing control apparatus according to a tenth embodiment of the present invention;  
       FIG. 20  illustrates a configuration example of a viewing control apparatus according to an eleventh embodiment of the present invention;  
       FIG. 21  illustrates a configuration example of a viewing control apparatus according to a twelfth embodiment of the present invention;  
       FIG. 22  illustrates a configuration example of a viewing control apparatus according to a thirteenth embodiment of the present invention;  
       FIG. 23  illustrates a configuration example of a viewing control apparatus according to a fourteenth embodiment of the present invention;  
       FIG. 24  illustrates a configuration example of a viewing control apparatus according to a fifteenth embodiment of the present invention;  
       FIG. 25  illustrates a configuration example of a viewing control apparatus according to a sixteenth embodiment of the present invention;  
       FIG. 26  illustrates a configuration example of a viewing control apparatus according to a seventeenth embodiment of the present invention; and  
       FIG. 27  illustrates a configuration example of a viewing control apparatus according to an eighteenth embodiment of the present invention. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      With reference now to the accompanying drawings, embodiments of the present invention will be explained below. The present invention is by no means limited by these embodiments and can be implemented in various modes without departing from the essence thereof.  
      (Embodiment 1)  
      A first embodiment of the present invention will explain the basic configuration of a viewing control apparatus that allows viewing of contents when an advertisement is viewed.  
      As shown in a block diagram in  FIG. 1 , this apparatus is provided with reproduction/broadcasting apparatus  101  that outputs advertisement  1011 , scrambled encrypted contents  1012  and ECM  1013  encrypted using a key Kw, secure module  102  that extracts a key Ks  103  from ECM  1013  using stored key Kw  1022 , descrambler  104  that decrypts encrypted contents  1012  using key Ks  103  and outputs decrypted contents  105  and display apparatus  106  that displays advertisement  1011  and decrypted contents  105 .  
      Reproduction/broadcasting apparatus  101  is a broadcasting apparatus that generates advertisement  1011 , encrypted contents  1012  and ECM  1013  and broadcasts and transmits them by radio or a wire circuit. Reproduction/broadcasting apparatus  101  also is a reproduction apparatus that stores, reproduces and outputs advertisement  1011 , encrypted contents  1012  and ECM  1013  received from this broadcasting apparatus. This advertisement  1011  includes EMM update request  10111  that specifies target contents and an expiration date for until which viewing the contents is allowed and this EMM update request  10111  is encrypted using key Kw  1022 . Furthermore, ECM  1013  includes information about key Ks  103  for descrambling contents and viewing enabled condition, and they are encrypted using key Kw  1022 .  
      Secure module  102  is mounted or incorporated in a reception apparatus and descrambler  104  forms a part of the reception apparatus. This secure module  102  stores EMM  1021  indicating contents viewing condition and key Kw  1022  for decrypting EMM update request  10111  and ECM  1013 . This EMM  1021  and key Kw  1022  are broadcasted beforehand and stored in the secure module  102  as in the case of the conventional system.  
      Secure module  102  is further provided with EMM updating section  1024  that decrypts EMM update request  10111  upon reception of EMM update request  10111  using key Kw  1022  and sets information about EMM update request  10111  (that is, contents specified by EMM update request  10111  and information about the expiration date for until which viewing of the contents is allowed) in EMM  1021 , and also provided with Ks extraction section  1023  that decrypts ECM  1013  using key Kw  1022 , identifies the contents described therein, compares the expiration date until which viewing of the contents is allowed set in EMM  1021  with the current time and extracts key Ks  103  from ECM  1013  when viewing is possible.  
      This secure module  102  is a so-called CAS card (card intended for conditional access) or IC card and is created with a medium which prevents unauthorized reading and writing of data from outside and which is destroyed when unauthorized access is made.  
      Note that EMM update request  10111  specifies an advertisement broadcasting time or a certain time from the advertisement stored time as an expiration date until which viewing the contents is allowed. The end time of the expiration date may be specified concretely or a certain time from a current time may be set as an expiration date.  
      The operation of this viewing control apparatus will be explained. First, reproduction/broadcasting apparatus  101  reproduces or broadcasts advertisement  1011  including EMM update request  10111  and encrypted contents  1012 . The advertisement  1011  and encrypted contents  1012  are not necessarily reproduced or broadcasted simultaneously. When encrypted contents  1012  are reproduced or broadcasted, ECM  1013  synchronized therewith is reproduced or broadcasted. The reproduced or broadcasted advertisement  1011  is displayed on display apparatus  106 .  
      EMM  1021  in secure module  102  initially sets all contents unavailable. Upon receiving EMM update request  10111  included in the displayed advertisement  1011 , EMM updating section  1024  of secure module  102  decrypts the request using key Kw  1022  and sets the contents specified by EMM update request EMM  10111  and an expiration date until which viewing of the contents is allowed in EMM  1021 .  
      Next, upon reception of ECM  1013 , Ks extraction section  1023  decrypts ECM  1013  using key Kw  1022 , identifies the contents described therein, compares the expiration date until which viewing of the contents is allowed set in EMM  1021  with the current time, extracts key Ks  103  from ECM  1013  and sends it out from secure module  102  when viewing is possible.  
      Descrambler  104  receives encrypted contents  1012  and key Ks  103 , decrypts the encrypted contents  1012  using key Ks  103  and sends decrypted contents  105 . These decrypted contents  105  are displayed on display apparatus  106 .  
      The viewing control by this viewing control apparatus enables viewing of the contents only when advertisement loll including EMM update request  10111  of the contents is viewed and the contents viewing time point falls within the expiration date specified by EMM update request  10111 .  
      EMM update request  10111  for contents can be included not only in advertisement  1011  broadcasted with the contents but also in advertisement  1011  broadcasted after the contents. In this case, viewing the recently broadcasted or stored advertisement satisfies the viewing condition and it is possible for viewers to reproduce or view the contents.  
      Next, the detailed operation of the viewing control apparatus that makes it possible to see the encrypted contents when an advertisement is viewed will be explained.  
      The viewing control apparatus stores encrypted contents  1012  encrypted using key Ks  103 , advertisement  1011 , key Kw  1022  for decrypting ECM  1013  and ECM  1013  in reproduction/broadcasting apparatus  101 . Encrypted contents  1012 , advertisement  1011 , key Kw  1022  and ECM  1013  may also be acquired via a network or broadcasting, or via a recording medium such as an SD card or DVD. A method of acquiring them is not particularly limited in the present invention.  
       FIG. 2  illustrates an example of the structure of advertisement  1011 .  
      Advertisement  1011  consists of advertisement body  1901  and EMM update request information  10111 . EMM update request information  10111  is encrypted using key Kw  1022  to prevent it from being rewritten by a third party.  
       FIG. 3  illustrates an example of the structure of EMM update request information  10111 .  
      EMM update request information loll stores contract information and is made up of contents ID  2001  for identifying encrypted contents and information  2002  indicating an expiration date until which the contents ID  2001  can be viewed as the content information. The expiration date consists of start time  2003  indicating a start time that authorizes viewing the encrypted contents represented by the contents ID and duration  2004  that relatively indicates the expiration date of the viewing authorization. Since start time  2003  and duration  2004  are based on the intent of an advertisement sponsor and are preset at a center. The contents of EMM update request information  10111  are the same as those of an EMM used in current digital broadcasting or the like. In the case of EMM update request information  10111  shown in  FIG. 3 , contents ID  2001  represents contents “ 100 ” , start time  2003  represents “ 2000 . 01 / 01 ” and duration  2004  represents “3 days.”  
      Next, the contents of ECM  1013  will be explained. The contents of ECM  1013  are the same as those of an ECM used in current digital broadcasting or the like and consist of contents ID  2001  for identifying encrypted contents and key Ks  103  with which the contents are encrypted.  
      Next, the contents of EMM  1021  will be explained. The contents of EMM  1021  are the same as those of an EMM used in current digital broadcasting or the like and consist of a list of contract information, and the contract information consists of contents ID  2001  for identifying encrypted contents that can be decrypted and an expiration date until which encrypted contents can be decrypted.  
      The advertisement reproduction operation of the viewing control apparatus when a viewer views an advertisement and the encrypted contents reproduction operation of the viewing control apparatus when the viewer views encrypted contents will be explained.  
       FIG. 4  illustrates a configuration example of EMM  1021  before the viewer views an advertisement.  
      Before the advertisement is viewed, the viewing control apparatus allows viewing of encrypted contents  1012  having a contents ID  2301  of “ 200 ” for 1 day from Jan. 1, 2000 and allows viewing of encrypted contents  1012  having a contents ID  2301  of “ 300 ” for 1 day from Jan. 2, 2000 but does not allow viewing of other encrypted contents  1012 .  
      The advertisement reproduction operation of the viewing control apparatus when the viewer views an advertisement on Jan. 1, 2000 under such a circumstance will be explained with reference to a flow chart in  FIG. 5 .  
      Reproduction/broadcasting apparatus  101  passes advertisement  1011  to display apparatus  106 . In this way, advertisement  1011  is reproduced and the viewer views the advertisement (step  2101 ).  
      Next, reproduction/broadcasting apparatus  101  passes EMM update request information  10111  included in advertisement  1011  to secure module  102  (step  2102 ). EMM updating section  1024  of secure module  102  decrypts EMM update request information  10111  using key Kw  1022  (step  2103 ).  
      EMM updating section  1024  writes contract information about EMM update request information  10111 ; contract information of EMM  1021  with contents ID  2001  of “ 100 ” , start time  2003  of “Jan. 1, 2000” and duration  2004  of “3 days” shown in  FIG. 3  in this example (step  2104 ).  
       FIG. 6  illustrates a state of EMM  1021  after the viewer views the advertisement.  
      According to EMM  1021  updated by EMM updating section  1024  based on EMM update request information  1011 , after the advertisement is viewed, the viewing control apparatus allows viewing of encrypted contents  1012  having contents ID  2301  of “ 100 ” for 3 days from Jan. 1, 2000 in addition to encrypted contents  1012  having contents ID  2301  of “ 200 ” and “ 300 ” as shown in  FIG. 4 .  
      Next, the encrypted contents reproduction operation of the viewing control apparatus when the viewer views the encrypted contents having contents ID  2301  of “ 100 ” on Jan. 2, 2000, the day after the viewer viewed the advertisement will be explained using a flow chart in  FIG. 7 .  
      Reproduction/broadcasting apparatus  101  passes encrypted contents  1012  having contents ID  2301  of “ 100 ” to descrambler  104  (step  2201 ).  
      Reproduction/broadcasting apparatus  101  passes ECM  1013  to Ks extraction section  1023  of secure module  102  (step  2202 ). Ks extraction section  1023  decrypts ECM  1013  using key Kw  1022  and acquires contents ID  2301  described in ECM  1013 . In this example, contents ID  2301  of “ 100 ” is acquired (step  2203 ).  
      KS extraction section  1023  checks whether or not contract information about contents ID  2301  of “ 100 ” is set in EMM  1021  (step  2204 ). When there is no contract information, decryption of the encrypted contents is suspended (step  2205 ).  
      Here, if the contract information is found, expiration date  2302  is acquired as the contract information from EMM  1021  shown in  FIG. 6  (step  2206 ). Ks extraction section  1023  also checks whether or not the current time is between start time  2303  of expiration date  2302  and (start time  2303 +duration  2304 ) (step  2207 ).  
      When the current time is not found between start time  2303  and (start time  2303 +duration  2304 ), decryption of encrypted contents  1012  having the contents ID  2301  of “ 100 ” is suspended (step  2208 ).  
      In this example, the current time is Jan. 2, 2000, start time  2303  is Jan. 1, 2000 and the (start time  2303 +duration  2304 ) is Jan. 4, 2000, and the current time is found between the two, and therefore the processing continues. When the current time is found between start time  2303  and (start time  2303 +duration  2304 ), Ks extraction section  1023  extracts key Ks  103  from ECM  1013  and sends it out to descrambler  104  (step  2209 ). When descrambler  104  acquires key Ks  103 , it decrypts the encrypted contents  1012  using key Ks  103  and passes it to display apparatus  106  (step  2210 ).  
      Note that though this embodiment illustrates the example using the digital broadcasting CAS technology (ECM, EMM) but the present invention is not limited to a CAS application of digital broadcasting and generally applicable to a contents delivery system having a system transmitting contract information, a system controlling it within a reception apparatus (equivalent to EMM) and a system transmitting key information and a system controlling it within the reception apparatus (equivalent to ECM).  
      Furthermore, this embodiment shows an example using the secure module, which is intended to prevent tampering of EMM information and key Kw or the like, and it is also possible to prevent tampering information about viewing control using a different system and the secure module is not the essential condition to the configuration.  
      Furthermore, this embodiment shows an example of using secure module  102  as a processing module for storing or updating viewing conditions such as EMM, but a nonsecure processing module can also be used.  
      Furthermore, this embodiment explains on the assumption that advertisements and contents are images, but advertisements and contents can be a mixture with audio or other data or only audio data. In such a case, a display apparatus can be any device that is capable of expressing advertisements and contents in their formats.  
      Note that it is also possible to calculate an expiration date for viewing contents using an arbitrary time point between an advertisement viewing start time and advertisement viewing end time or an advertisement acquisition time as a reference time.  
      Thus, prior to viewing of contents, this viewing control apparatus is capable of showing not an accumulated and stored old advertisement but an advertisement effective at the time of viewing. Consequently, an advertiser can acquire means for effectively showing a new advertisement of merchandise or the like, while a viewer can view contents free of charge by viewing the advertisement. Furthermore, a contents provider can earn advertisement revenue from contents broadcasted in the past.  
      (Second Embodiment)  
      A second embodiment of the present invention will explain a viewing control apparatus that allows viewing of contents when an advertisement is viewed from its beginning to end.  
      As shown in  FIG. 8 , in this apparatus, an end of advertisement  2011  sent out from reproduction/broadcasting apparatus  201  includes EMM update request encrypted using key Kw  2022  that is further encrypted using key Kw 2  ( 2025 ), and a beginning of advertisement  2011  includes kw 2  information  20112  that is key Kw 2  ( 2025 ) encrypted using key Kw  2022 . The information content of EMM update request  2  ( 20111 ) is the same as EMM update request  10111  in the first embodiment and describes target contents and the expiration date until which viewing of the contents is allowed.  
      On the other hand, secure module  202  is provided with Kw 2  extraction section  2024  that decrypts Kw 2  information  20112  using key Kw  2022  and extracts key Kw 2  ( 2025 ) and EMM updating section  2023  that decrypts EMM update request  2  ( 20111 ) using key Kw 2  ( 2025 ), further decrypts the information using key Kw  2022  and sets information about EMM update request  2  ( 20111 ) obtained in EMM  2021 . The rest of the configuration is the same as that of the first embodiment ( FIG. 1 ) (in  FIG. 8 , some parts such as a display apparatus  106  and descrambler  104  are omitted).  
      The operation of this viewing control apparatus will be explained with reference to  FIG. 9 .  
      First, reproduction/broadcasting apparatus  201  reproduces or broadcasts advertisement  2011  including EMM update request  2  ( 20111 ) and Kw 2  information  20112  and advertisement  2011  is displayed on display apparatus  106  (step  3101 ). Kw 2  information  20112  is reproduced or broadcasted at the beginning of an advertisement (step  3102 ) and upon reception of Kw 2  information  20112 , Kw 2  extraction section  2024  decrypts Kw 2  information  20112  using key Kw  2022  (step  3103 ) and extracts key Kw 2  ( 2025 ) (step  3104 ).  
      Next, EMM update request  2  ( 20111 ) is reproduced or broadcasted at the end of the advertisement (step  3105 ), and upon reception of EMM update request  2  ( 20111 ) (step  3106 ), EMM updating section  2023  decrypts this using key Kw 2  ( 2025 ) (step  3107 ), decrypts the information using key Kw  2022  and sets information that enables viewing the contents specified by EMM update request  2  ( 20111 ) until the expiration date in EMM  2021  (step  3108 ).  
      Then, the display of the contents is controlled based on the information set in EMM  2021  as in the case of the first embodiment.  
      In this way, this viewing control apparatus does not allow viewing of contents without viewing the beginning and end of an advertisement, and can thereby ensure that the advertisement is viewed.  
      (Third Embodiment)  
      A third embodiment will explain a viewing control apparatus that allows viewing of contents when an advertisement is viewed from beginning to end without fast forwarding.  
      This apparatus, as shown in  FIG. 10 , includes EMM update request  2  ( 30111 ) having advertisement viewing time information  301111  indicating a viewing time of advertisement  3011 .  
      On the other hand, secure module  302  is provided with advertisement viewing time decision section  3026  that measures a time from after Kw 2  information  30112  is received until EMM update request  2  ( 30111 ) is received and deletes the contents viewing information set in EMM  3021  when the measured time is different from advertisement viewing time information  301111 . The rest of the configuration is the same as that of the second embodiment ( FIG. 8 ).  
      The operation of this viewing control apparatus will be explained with reference to  FIG. 11 .  
      First, reproduction/broadcasting apparatus  301  reproduces or broadcasts advertisement  3011  including EMM update request  2  ( 30111 ) and Kw 2  information  30112  and the advertisement is displayed (step  4101 ). EMM update request  2  ( 30111 ) includes advertisement viewing time information  301111  on a viewing time of the advertisement.  
      Kw 2  information  30112  is reproduced or broadcasted at the beginning of an advertisement (step  4102 ) and upon reception of Kw 2  information  30112  (step  4103 ), Kw 2  extraction section  3024  decrypts Kw 2  information  30112  using key Kw  3022  and extracts key Kw 2  ( 3025 ) (step  4105 ). Advertisement viewing time decision section  3026  stores the reception time of Kw 2  information  30112  (step  4104 ).  
      Next, EMM update request  2  ( 30111 ) is reproduced or broadcasted at the end of the advertisement (step  4106 ), and upon reception of EMM update request  2  ( 30111 ) (step  4107 ), EMM updating section  2  ( 3023 ) decrypts EMM update request  2  ( 30111 ) using key Kw  2  ( 3025 ) (step  4109 ), further decrypts the information using key Kw  3022  and sets information that the contents specified by EMM update request  2  ( 30111 ) can be viewed until the expiration date in EMM  3021 . Advertisement viewing time decision section  3026  stores the reception time of EMM update request  2  ( 30111 ) (step  4108 ).  
      Next, advertisement viewing time decision section  3026  measures the time after Kw  2  information  30112  is received until EMM update request  2  ( 30111 ) is received, compares the measured time with the advertisement viewing time information  301111  (step  4110 ), deletes viewing information of the contents set in EMM  3021  when the two are different (step  4111 ) and sets information that the contents specified by EMM update request  2  ( 30111 ) can be viewed until the expiration date in EMM  3021  when the two match as in the case of the second embodiment (step  4112 ).  
      Then, the display of the contents is controlled based on the information set in EMM  3021  as in the case of the first embodiment.  
      In this way, this viewing control apparatus measures the time interval between the beginning time and the ending time of viewing the advertisement and can thereby prevent fast forwarding or the like of the advertisement.  
      (Fourth Embodiment)  
      A fourth embodiment of the present invention will explain a viewing control apparatus that sets check points not only at the beginning and end of an advertisement but also at some midpoints of the advertisement at certain time intervals, verifies that the time intervals between check points are viewed without fast forwarding and then allows viewing of the contents.  
      As shown in  FIG. 12 , in this apparatus, an advertisement  4011  sent out from a reproduction/broadcasting apparatus  401  includes key information Kcm  40112  issued at each check point and an EMM update request  2  ( 40111 ) issued at the end of the advertisement  4011 . Key information Kcm  40112  is information obtained by encrypting different keys Kcm  4025  set at respective check points and issued at certain intervals during viewing of the advertisement. Key information Kcm  40112  issued at the beginning is information obtained by encrypting key Kcl set at the first check point using key Kw  4022  and key information Kcm  40112  issued next is information obtained by encrypting key Kc 2  set at the next check point using key Kcl set at the previous check point. Key Kcm set at check points are encrypted using another key Kcm set at its immediately preceding check point and issued as key information Kcm  40112  one after another.  
      In addition, EMM update request  2  ( 40111 ) is encrypted using key Kw  4022  and then further encrypted using key Kcm  4025  set at the last checkpoint. This EMM update request  2  ( 40111 ) describes target contents and a duration during which viewing of the contents is allowed and further describes advertisement viewing time information  401111  indicating issuance time intervals of respective parts of Kcm information  40112 .  
      On the other hand, secure module  402  is provided with Kcm extraction section  4024 , EMM updating section  4023  and advertisement viewing time decision section  4026 . Kcm extraction section  4024  decrypts initially issued part of Kcm information  40112  using Key Kw  4022 , extracts key Kcm  4025 , decrypts second and subsequently issued part of Kcm information  40112  using Kcm  4025  extracted from the immediately preceding part of Kcm information  40112  and extracts key Kcm  4025 . EMM updating section  4023  decrypts, upon reception of EMM update request  2  ( 40111 ), EMM update request  2  ( 40111 ) using key Kcm  4025  extracted last by Kcm extraction section  4024 , further decrypts the information using key Kw  4022  and sets the contents specified by EMM update request  2  ( 40111 ) and duration during which viewing of the contents is allowed in EMM  4021 . Advertisement viewing time decision section  4026  measures a time between check points after Kcm information  40112  is received until EMM update request  2  ( 40111 ) is received and deletes contents viewing information set in EMM  4021  when the measured time is different from advertisement viewing time information  401111 . The rest of the configuration is the same as that of the second embodiment ( FIG. 8 ).  
      The operation of this viewing control apparatus will be explained with reference to  FIG. 13 .  
      First, reproduction/broadcasting apparatus  401  reproduces or broadcasts advertisement  4011  including EMM update request  2  ( 40111 ) and Kcm information  40112  and displays advertisement  4011  (step  5101 ). EMM update request  2  ( 40111 ) includes advertisement viewing time information  401111  on the viewing time of the advertisement.  
      Kcm information  40112  is sequentially sent out during reproduction or broadcasting of the advertisement (step  5102 ), and upon reception of Kcm information  40112  (step  5103 ), Kcm extraction section  4024  decrypts the initially issued part of Kcm information  40112  using key Kw  4022  and extracts key Kcm  4025  (step  5105 ). In that case, advertisement viewing time decision section  4026  stores the reception time of Kcm information  40112  (step  5104 ).  
      Likewise, when the second and subsequent issued parts of Kcm information  40112  are sequentially sent out during reproduction or broadcasting of the advertisement (step  5106 ) and received by Kcm extraction section  4024  (step  5107 ), the information is decrypted using key Kcm  4025  extracted from the immediately preceding Kcm information and key Kcm  4025  is sequentially extracted (step  5109 ). In that case, advertisement viewing time decision section  4026  stores the times at which the second and subsequent issued parts of Kcm information  40112  are received (step  5108 ). When the issuance interval of Kcm information  40112  is different from the issuance interval set in advertisement viewing time information  401111 , advertisement viewing time decision section  4026  deletes key Kcm  4025  so as to prevent subsequent keys Kcm  4025  or EMM update request  2  ( 40111 ) from being decrypted.  
      Next, when EMM update request  2  ( 40111 ) is reproduced or broadcasted at the end of the advertisement (step  5110 ), EMM updating section  2  ( 4023 ) receives EMM update request  2  ( 40111 ) (step  5111 ), decrypts EMM update request  2  ( 40111 ) using key Kcm  4025  extracted last by Kcm extraction section  4024  (step  5113 ), further decrypts the information using key Kw  4022  and sets the contents described in EMM update request  2  ( 40111 ) and expiration date until which viewing of the contents is allowed in EMM  4021 . Note advertisement viewing time decision section  4026  stores the time at which EMM update request  2  ( 40111 ) is received (step  5112 ).  
      Next, advertisement viewing time decision section  4026  measures the time after Kcm information  40112  is received until EMM update request  2  ( 40111 ) is received, compares the measured time with advertisement viewing time information  401111  (step  5114 ), when they are different, deletes the contents viewing information set in EMM  4021  (step  5115 ) and, when the two match, sets information that the contents specified by EMM update request  2  ( 40111 ) can be viewed until the expiration date in EMM  4021  as in the case of the second embodiment (step  5116 ).  
      Thereafter, like the case of the first embodiment, the display of the contents is controlled based on the information set in EMM  4021 .  
      Thus, this viewing control apparatus does not allow key for viewing contents to be obtained unless all of the plurality of points in the advertisement are viewed without carrying out fast forwarding or the like. Therefore, it is possible to reliably prevent fast forwarding or the like of the advertisement and ensure that the advertisement is viewed.  
      (Fifth Embodiment)  
      A fifth embodiment will explain a viewing control apparatus that prevents the time of a secure module from being illegally changed.  
      The present invention sets an expiration date until which viewing of the contents is allowed by viewing the advertisement, but implementing this system requires the precise time of the secure module for controlling the expiration date. The time of the secure module is conventionally constructed so as to be corrected by acquiring time information from the outside, for example, once a day when power is turned on, but there is a possibility that the time of the secure module may be illegally changed or manipulated by intentionally giving wrong information at the time of this correction. The viewing control apparatus in this embodiment will prevent such illegal manipulation.  
      As shown in  FIG. 14 , this apparatus is provided with time correction site  501  that transmits time information and secure module  502  that receives the time information from time correction site  501  and corrects information about the stored current time. Time correction site  501  stores key Kw  5012  and is provided with time information creation section  5011  that encrypts the time information using key Kt  5024  sent from secure module  502  and sends it.  
      On the other hand, secure module  502  is provided with key generation section  5022  that stores key Kw  5021  and generates key Kt  5024  for encrypting time information randomly and time correction section  5023  that decrypts time information received from time correction site  501  and corrects the time of secure module  502 .  
      The operation of this viewing control apparatus will be explained. First, when correcting the current time inside the secure module, key generation section  5022  generates key Kt  5024  randomly, encrypts the key using key Kw  5021  and sends it to time correction site  501 .  
      Next, upon reception of the encrypted key Kt  5024 , time information creation section  5011  of time correction site  501  decrypts it using key Kw  5021 , encrypts the current time of time correction site  501  using key Kt  5024  obtained by decryption and sends it to secure module  502 .  
      Next, time correction section  5023  of secure module  502  decrypts the received time information using key Kt  5024  and corrects the time of the secure module.  
      In this way, this viewing control apparatus does not allow the time of the secure module to be illegally changed, and can thereby accurately control a contents viewing expiration date and ensures that an effective advertisement is shown when contents are viewed.  
      (Sixth Embodiment)  
      A sixth embodiment of the present invention will explain a viewing control apparatus capable of arbitrarily selecting a method of viewing contents free of charge by seeing an advertisement or a method of viewing contents on a charged basis through PPV.  
      As shown in  FIG. 15 , in this apparatus, reproduction/broadcasting apparatus  601  sends advertisement  6011  including EMM update request  60111  and PPV information  6012  obtained by encrypting information about an amount of money necessary to purchase a contents viewing right and expiration date of purchasing the contents viewing right or the like using key Kw  6022 . On the other hand, the reception apparatus is provided with viewing right purchasing operation section  603  that carries out operation of purchasing the contents viewing right and secure module  602  is provided with not only EMM  6021 , key Kw  6022  and EMM updating section  6023  but also PPV operation section  6024  that sets information that the contents viewing right has been purchased in EMM  6021  when an operation of purchasing the contents viewing right specified by PPV information  6012  within the specified expiration date is carried out by viewing right purchasing operation section  603 . Upon reception of EMM update request  60111 , EMM updating section  6023  decrypts it using key Kw  6022  and sets the contents described in EMM update request  60111  and expiration date until which viewing of the contents is allowed in EMM  6021 , but EMM updating section  6023  does not perform this processing when information that the contents viewing right has been purchased is set in EMM  6021 . The rest of the configuration is the same as that in the first embodiment ( FIG. 1 ).  
      The operation of this viewing control apparatus will be explained. First, reproduction/broadcasting apparatus  601  reproduces or broadcasts advertisement  6011  including EMM update request  60111  and PPV information  6012 .  
      When an operation of purchasing the contents viewing right is carried out by viewing right purchasing operation section  603 , PPV operation section  6024  of secure module  602  receives PPV information  6012  on the purchase of the contents viewing right, decrypts the information using key Kw  6022  and sets information that the contents viewing right has been purchased in EMM  6021  when the current time is included within the expiration date of purchasing of the viewing right specified by PPV information  6012 .  
      Upon reception of EMM update request  60111 , EMM updating section  6023  decrypts it using key Kw  6022  and discards EMM update request  60111  when EMM update request  60111  is associated with the contents for which information that the contents viewing right has been purchased is set in EMM  6021 . In other cases, EMM updating section  6023  sets the contents specified by EMM update request  60111  and information about the expiration date until which viewing of the contents is allowed in EMM  6021 .  
      Thereafter, as in the case of the first embodiment, the display of the contents is controlled based on the information set in EMM  6021 .  
      In this way, this viewing control apparatus allows the viewer to purchase a viewing right to view contents instead of viewing an advertisement. In this case, by specifying an expiration date of purchasing the viewing right, it is possible to purchase the viewing right with the amount of money for purchasing the viewing right set in the latest PPV information.  
      (Seventh Embodiment)  
      A seventh embodiment of the present invention will explain a viewing control apparatus capable of acquiring information about an advertisement necessary to view contents in advance.  
      As shown in  FIG. 16 , in this apparatus, broadcasting apparatus  701  that broadcasts contents broadcasts EPG  7012  describing program information of contents in advance and then broadcasts advertisement  7011  including EMM update request  70111 , scrambled encrypted contents  7013  and ECM  7014  obtained by encrypting a contents scramble key and a viewing condition. This EPG  7012  includes advertisement-related information  70121  describing list information of contents on advertisements necessary to view the contents (including advertisement insertion points in contents and correspondence with advertisements to be viewed at the respective points), information about an expiration date until which viewing of the contents is allowed and site information in which the updated information is described when such information is updated.  
      Storage/reproduction apparatus  702  that stores and reproduces contents to be broadcasted extracts advertisement-related information  7024  from the received EPG  7012  and stores it and also stores advertisement  7021  including received EMM update request  70211 , encrypted contents  7022  and ECM  7023 .  
      The operation of this viewing control apparatus will be explained. First, broadcasting apparatus  701  broadcasts EPG  7012  and storage/reproduction apparatus  702  stores the advertisement-related information  7024  extracted from EPG  7012  of the contents to be stored.  
      Next, broadcasting apparatus  701  broadcasts the advertisement  7011 , encrypted contents  7013  and ECM  7014  and the storage/reproduction apparatus  702  receives them and stores the advertisement  7021 , encrypted contents  7022  and ECM  7023 .  
      This storage/reproduction apparatus  702  functions as reproduction/broadcasting apparatus  101  in the first embodiment ( FIG. 1 ) and outputs stored advertisement  7021 , encrypted contents  7022  and ECM  7023  when contents are reproduced. Furthermore, when the expiration date is past and viewing of the contents is no longer allowed with the stored advertisement, it is possible to acquire information about the latest advertisement necessary to view the contents from the site described in advertisement-related information  7024  and receive the advertisement by means of broadcasting.  
      Thus, this viewing control apparatus can acquire information about an advertisement necessary to view contents in advance and obtain, even when the information about the advertisement is updated, information for acquiring the latest advertisement.  
      (Eighth Embodiment)  
      An eighth embodiment of the present invention will explain a viewing control apparatus that acquires, before contents stored in the past or contents delivered with media such as DVD are viewed, an advertisement necessary to view the contents.  
      As shown in  FIG. 17 , in this apparatus, broadcasting apparatus  801  broadcasts advertisement  8011  including EMM update request  80111  and EPG  8012  including advertisement-related information  80121 , and a storage/reproduction apparatus  802  stores advertisement  8021  stored in the past, encrypted contents  8022 , ECM  8023  and advertisement-related information  8024 . Furthermore, storage/reproduction apparatus  802  is provided with reservation section  8025  that reserves viewing of contents  8022  stored in the past or contents delivered with media such as DVD and advertisement update section  8026  that updates stored advertisement  8021  and advertisement-related information  8024 . Advertisement update section  8026  acquires the advertisement and advertisement-related information to be updated from broadcasting apparatus  801  or advertisement issuing site  803 .  
      The operation of this viewing control apparatus will be explained. First, the viewer reserves viewing of contents stored in the past or contents delivered with media such as DVD by reservation section  8025 .  
      Next, advertisement update section  8026  references expiration date information from stored advertisement-related information  8024  of contents, viewing of which is reserved, references EPG  8012  broadcasted from broadcasting apparatus  801  when the time from which the viewing is reserved to start is after the expiration date, makes a reservation so as to store an advertisement necessary to view target contents, receives the advertisement  8011  and advertisement-related information  80121  to be broadcasted at the reserved time and updates advertisement  8021  and advertisement-related information  8024 .  
      Furthermore, when the latest advertisement  8011  and advertisement-related information  80121  are not broadcasted by the time from which viewing of the contents is reserved to start, advertisement update section  8026  requests advertisement  8011  and advertisement-related information  80121  from advertisement issuing site  803  via a network, acquires them and updates advertisement  8021  and advertisement-related information  8024 .  
      This storage/reproduction apparatus  802  functions as reproduction/broadcasting apparatus  101  in the first embodiment ( FIG. 1 ).  
      Note that EPG  8012  may be related to a content broadcasting schedule or advertisement broadcasting schedule.  
      In this way, when viewing contents stored in the past or contents delivered with media such as DVD, this viewing control apparatus can acquire the latest advertisement necessary to view the contents before the viewing.  
      (Ninth Embodiment)  
      A ninth embodiment of the present invention will explain a viewing control apparatus capable of performing viewing control under the condition that a viewer should view an advertisement when viewing copied contents.  
      As shown in  FIG. 18 , in this apparatus, storage/reproduction apparatuses  901  and  902  that store and reproduce contents are provided with copy control sections  9015  and  9025  that control copying of contents, and when contents are copied from storage/reproduction apparatus  901  to storage/reproduction apparatus  902 , advertisement  9011  including EMM update request  90111 , advertisement-related information  9014 , encrypted contents  9012  and ECM  9013  stored in storage/reproduction apparatus  901  which is the copy source are copied to storage/reproduction apparatus  902  which is the copy destination and stored as advertisement  9021  including EMM update request  90211 , advertisement-related information  9024 , encrypted contents  9022  and ECM  9023 .  
      The operation of this viewing control apparatus will be explained. First, when contents are copied, copy control section  9025  requests copy control section  9015  to make a copy of contents or copy control section  9015  instructs copy control section  9025  to make a copy of the contents.  
      Next, copy control section  9015  sends advertisement  9011  of the corresponding contents, encrypted contents  9012 , ECM  9013  and advertisement-related information  9014  to storage/reproduction apparatus  902 .  
      Next, copy control section  9025  stores the received information as advertisement  9021 , encrypted contents  9022 , ECM  9023  and advertisement-related information  9024  respectively.  
      This storage/reproduction apparatus  902  functions as reproduction/broadcasting apparatus  101  in the first embodiment ( FIG. 1 ).  
      In this way, when contents are copied, this viewing control apparatus also copies information necessary for viewing control, and therefore when the copied contents are viewed, it is possible to execute viewing control which allows viewing of contents on condition of viewing an advertisement as in the case of the original contents.  
      (Tenth Embodiment)  
      A tenth embodiment of the present invention will explain a viewing control apparatus that collectively controls viewing control information (EMM update request, advertisement-related information) on contents making up a group.  
      Examples of the contents making up a group include a series program and contents included in the same genre. When contents of the same group are viewed, an advertiser shows the same or related advertisement and thereby expects improvement of advertising effects.  
      As shown in  FIG. 19 , in this apparatus, advertisement issuing site  1000  is provided with group viewing control information  1001  including advertisement-related information related to an advertisement necessary to view contents for groups and EMM update request, group/contents correspondence information  1002  which is information about contents belonging to the group and viewing information creation section  1003  that creates EMM update request  1004  and advertisement-related information  1005  necessary for respective contents from information.  
      The operation of this viewing control apparatus will be explained. First, viewing information creation section  1003  identifies contents belonging to the same group from group/contents correspondence information  1002  and creates EMM update request  1004  and advertisement-related information  1005  necessary for the respective contents based on the group viewing control information  1001 .  
      EMM update request  1004  and advertisement-related information  1005  set for the respective contents are sent to the broadcasting apparatus in the seventh embodiment ( FIG. 16 ) or the eighth embodiment ( FIG. 17 ), where an advertisement including an EMM update request and EPG including advertisement-related information is created.  
      In this way, this viewing control apparatus eliminates the necessity for carrying out management of contents viewing control for respective contents and it is possible to manage viewing control over a large amount of contents.  
      (Eleventh Embodiment)  
      An eleventh embodiment of the present invention will explain a viewing control apparatus that collects a viewing history of an advertisement.  
      As shown in  FIG. 20 , in this apparatus, secure module  1102  is provided with history information management section  11024  that stores an advertisement viewing history and reports it to advertisement issuing site  1101  in addition to EMM  11021 , key Kw  11022  and EMM updating section  11023  and advertisement issuing site  1101  is provided with advertisement viewing history collection section  11011  that stores key Kw  11012  used to decrypt received viewing history information or encrypt a response thereto, receives the advertisement viewing history and returns a response.  
      History information management section  11024  stores information about viewed advertisement, encrypts the number of times each advertisement is viewed using Kw  11022  and reports it to each advertisement issuing site  1101  when the storage area of the advertisement viewing history information within the secure module becomes full or at predetermined time intervals. Furthermore, when it is not possible to report the advertisement viewing history information within a report period, viewing of contents through viewing of subsequent advertisements will be disabled assuming that some illegal manipulation has been conducted.  
      The operation of this viewing control apparatus will be explained. First, history information management section  11024  of secure module  1102  stores viewing history of an advertisement, accumulates information of viewed advertisement, sets the operation of EMM updating section  11023  disabled for predetermined intervals or when the storage area of the advertisement viewing history information within the secure module becomes full before the end of that period, encrypts the number of times each advertisement is viewed using key Kw  11022  and sends it to advertisement issuing site  1101 .  
      Next, advertisement viewing history collection section  11011  of advertisement issuing site  1101  decrypts the number of times the received advertisement is viewed using key Kw  11012 . When this report is proven to be legitimate, operation of EMM updating section  11023  is enabled and a response for instructing deletion of reported advertisement viewing history information is encrypted using key Kw  11012  and sent to the secure module  1102 . Furthermore, advertisement issuing site  1101  collects an advertisement fee from an advertiser based on the collected number of times the advertisement is viewed.  
      Secure module  1102  that has received a response from advertisement issuing site  1101  decrypts it using key Kw  11021  and carries out processing according to the instruction.  
      In this way, this viewing control apparatus can keep track of a viewing situation of an advertisement without any falsity. Furthermore, when the advertisement viewing history information is not reported, it is possible to prevent viewing of contents.  
      (Twelfth Embodiment)  
      A twelfth embodiment of the present invention will explain a viewing control apparatus that collects an advertisement viewing history efficiently.  
      This apparatus collects an advertisement viewing history to be sampled and decides a viewing situation of other advertisements.  
      As shown in  FIG. 21 , in this apparatus, EMM update request  120311  of an advertisement  12031  output by reproduction/broadcasting apparatus  1203  includes announcement information  1203111  indicating whether or not the advertisement viewing history information should be reported to advertisement issuing site  1201 . Announcement information  1203111  of advertisements is set by advertisement issuing site  1201 . History information management section  12024  of secure module  1202  reports only a viewing history of an advertisement accompanied by announcement information  1203111  “to be reported” to advertisement issuing site  1201 . Advertisement issuing site  1201  stores favorable reception ranking information  12013  of various advertisements collected using other methods, references this ranking information  12013  and decides the viewing situations of other advertisements from the collected advertisement viewing history information (sampling data).  
      The operation of this viewing control apparatus will be explained. First, reproduction/broadcasting apparatus  1203  reproduces or broadcasts the advertisement  12031  including EMM update request  120311 . Advertisement  12031  is displayed on a display apparatus. EMM update request  120311  includes announcement information  1203111  indicating whether or not viewing information about the advertisement should be reported to advertisement issuing site  1201 .  
      Next, upon reception of EMM update request  120311 , EMM updating section  12023  of secure module  1202  decrypts it using key Kw  12022  and sets information that viewing of the contents specified by EMM update request  120311  is allowed until specified expiration date in EMM  12021 . In that case, the information about the advertisement viewed together with announcement information  1203111  is stored in history information management section  12024 .  
      Next, history information management section  12024  sends information about the number of times the advertisement accompanied by the announcement information  1203111  “to be reported” is viewed to advertisement issuing site  1201  and advertisement viewing history collection section  12011  of advertisement issuing site  1201  receives this and returns a response to secure module  1202 . The operation in this period is the same as the operation in the eleventh embodiment.  
      Next, advertisement viewing history collection section  12011 , based on a viewing count a of a reported advertisement A, calculates a viewing count b of advertisement B which is described in ranking information yet a viewing count of which is not reported through a calculation of proportion between the ranking and viewing count a of advertisement A and the ranking and viewing count b of advertisement B.  
      In this way, this viewing control apparatus can efficiently collect information about an advertisement viewing history.  
      (Thirteenth Embodiment)  
      A thirteenth embodiment of the present invention will explain a viewing control apparatus that allows, when broadcast contents are viewed in real time, a viewer who starts to view the contents in the middle of broadcasting to view up to the end of the contents.  
      A viewer, who starts to view a live broadcast program from some midpoint thereof, naturally, does not see an advertisement broadcasted at the beginning of the program. In this case, it is unfair to prevent the viewer from viewing the program for the reason that the viewer does not view the advertisement. This viewing control apparatus will relieve such a case.  
      As shown in  FIG. 22 , in this apparatus, broadcasting apparatus  1301  broadcasts an advertisement  13011  including an EMM update request  130111  and an EPG  13012  including an fixed-term EMM update request  130121  obtained by encrypting real broadcasting times of respective contents and advertisement broadcasting time using key Kw  13022 . In addition to EMM  13021 , key Kw  13022  and EMM updating section  13023 , a secure module  1302  is provided with fixed-term EMM update request management section  13024  that receives fixed-term EMM update request  130121 , decrypts it using key Kw  13022  and sets information that viewing of the contents is allowed during a real broadcasting time described in the fixed-term EMM update request  130121  in EMM  13021 .  
      The operation of this viewing control apparatus will be explained. The broadcasting apparatus  1301  broadcasts the EPG  13012  including the fixed-term EMM update request  130121  together with encrypted contents and ECM and also broadcasts an advertisement  13011  including EMM update request  130111  at an insertion point of an advertisement.  
      When this broadcasting is viewed at some midpoint thereof, fixed-term EMM update request management section  13024  of secure module  1302  receives EPG  13012 , decrypts fixed-term EMM update request  130121  therein using key Kw  13022  and sets information that viewing of the contents described in fixed-term EMM update request  130121  is allowed during a real broadcasting time in EMM  13021 . As a result, viewing of the contents is allowed until the real broadcasting time of the contents ends.  
      Next, when advertisement  13011  inserted at some midpoint of the program is viewed and EMM updating section  13023  receives EMM update request  130111 , EMM updating section  13023  decrypts it using key Kw  13022  and sets information that viewing of the contents described in EMM update request  130111  is allowed until the expiration date described in EMM update request  130111  in EMM  13021 . At this time, when fixed-term EMM update request management section  13024  has already set a contents viewing time longer than the expiration date in EMM  13021 , the setting based on EMM update request  130111  is not performed.  
      In this way, when this broadcasting is viewed at some midpoint, this viewing control apparatus allows the contents to be viewed up to the end. However, when broadcast contents are stored, the contents cannot be viewed unless the advertisement is viewed and EMM is updated by an EMM update request.  
      (Fourteenth Embodiment)  
      A fourteenth embodiment of the present invention will explain a viewing control apparatus that controls so that a viewer who starts to view this broadcasting at some midpoint thereof views an advertisement inserted at a later time point without skipping.  
      As shown in  FIG. 23 , in this apparatus, EPG  14012  broadcasted from broadcasting apparatus  1401  includes encrypted advertisement-related information  140121  obtained by encrypting a real broadcasting time of contents and broadcasting time of an advertisement using a key Kw  14022 , and secure module  1402  is provided with encrypted advertisement-related information management section  14024  that receives encrypted advertisement-related information  140121 , decrypts it using key Kw  14022  and sets information that viewing of contents described in encrypted advertisement-related information  140121  is allowed from a current time until the next advertisement is broadcasted in EMM  14021 . The rest of the configuration is the same as the thirteenth embodiment ( FIG. 22 ).  
      The operation of this viewing control apparatus will be explained. Broadcasting apparatus  1401  broadcasts EPG  14012  including encrypted advertisement-related information  140121  together with the encrypted contents and ECM and also broadcasts advertisement  14011  including EMM update request  140111  at an advertisement insertion point.  
      When this broadcasting is viewed at some midpoint thereof, the encrypted advertisement-related information management section  14024  of secure module  1402  receives encrypted advertisement-related information  140121 , decrypts it using key Kw  14022  and sets information that viewing of contents described in encrypted advertisement-related information  140121  is allowed from a current time until the next advertisement is broadcasted in EMM  14021 . Note that once a viewing time for the contents is set in EMM  14021 , no updating is performed.  
      Next, when advertisement  14011  inserted at some midpoint of the program is viewed and EMM updating section  14023  receives EMM update request  140111 , EMM updating section  14023  decrypts it using key Kw  14022  and sets information that viewing of the contents described in EMM update request  140111  is allowed until an expiration date described in EMM update request  140111  in EMM  14021 .  
      In this way, when this broadcasting is viewed at some midpoint thereof, this viewing control apparatus makes it possible to view the contents until the next advertisement is broadcasted and after that, unless the advertisement is viewed, it is not possible to view the contents. Therefore, it is possible to view contents even when viewing starts at some midpoint of this broadcasting and let the viewer continue to view the broadcasting once the viewing is started without skipping the advertisement.  
      (Fifteenth Embodiment)  
      A fifteenth embodiment of the present invention will explain a viewing control apparatus that applies a scheme of allowing viewing of contents under the condition of viewing an advertisement to contents encrypted using one key.  
      Encrypting contents using one key is widely practiced for digital copyright management (DRM) and many contents sold on the Internet are encrypted under this scheme.  
      The viewing control apparatus of this embodiment allows the viewer to view contents encrypted using one key if the viewer views an advertisement and thereby provides an advertiser with an effective place for the advertisement and gives the user an opportunity to view contents free of charge.  
      As shown in  FIG. 24 , this apparatus is provided with reproduction/broadcasting apparatus  1501  that reproduces or broadcasts encrypted contents, secure module  1502  that decrypts contents and display apparatus  1504  that displays advertisements and contents.  
      Reproduction/broadcasting apparatus  1501  outputs encrypted contents  15012  encrypted using one key (Ks Contents), Ks contents information  15013  which is a contents identification number and information about key Ks Contents used to decrypt contents encrypted using key Kw  15022  and advertisement  15011  necessary to view contents. Advertisement  15011  includes EMM update request  150111  describing specific information about contents and expiration date until which viewing is allowed and EMM update request  150111  is encrypted using key Kw  15022 .  
      This advertisement  15011 , KS Contents information  15013  and encrypted contents  15012  are recorded as one piece of data in a recording medium such as DVD and reproduction/broadcasting apparatus  1501  reproduces this recording medium, outputs advertisement  15011 , Ks Contents information  15013  and encrypted contents  15012  or sends out the reproduced information over a network.  
      Secure module  1502  stores EMM  15021  that defines a contents viewing condition and key Kw  15022  that decrypts EMM update request  150111  and Ks Contents information  15013  and is provided with EMM updating section  15024  that decrypts EMM update request  150111  using key Kw  15022  and sets information that viewing of contents described in EMM update request  150111  is allowed until an expiration date described in EMM update request  150111  in EMM  15021 , Ks Contents extraction section  15025  that decrypts Ks Contents information  15013  using key Kw  15022  and extracts key Ks Contents and descrambler  15023  that decrypts encrypted contents  15012  using key Ks Contents extracted by Ks Contents extraction section  15025  and outputs decrypted contents  1503 . Note that, since encrypted contents  15012  are encrypted using one key Ks Contents, leakage of key causes a considerable damage. For this reason, this apparatus places the descrambler  15023  in a highly confidential secure module  1502 .  
      Furthermore, display apparatus  1504  displays advertisement  15011  output from reproduction/broadcasting apparatus  1501  and decrypted contents  1503  output from secure module  1502 .  
      The operation of this viewing control apparatus will be explained. First, reproduction/broadcasting apparatus  1501  reproduces or broadcasts advertisement  15011  including EMM update request  150111 , encrypted contents  15012  and Ks Contents information  15013 . Advertisement  15011  is displayed on display apparatus  1504 .  
      EMM  15021  in secure module  1502  is initially set to be unable to view any contents. Upon reception of EMM update request  150111 , EMM updating section  15024  decrypts it using key Kw  15022  and sets information that viewing of the contents described in EMM update request  150111  is allowed until the expiration date described in EMM update request  150111  in EMM  15021 .  
      Next, Ks Contents extraction section  15025  decrypts Ks Contents information  15013  using key Kw  15022  and extracts key Ks Contents.  
      Next, descrambler  15023  receives encrypted contents  15012 , compares the expiration date until which viewing of the contents is allowed set in EMM  15021  with a current time, decrypts encrypted contents  15012  using key Ks Contents when viewing is allowed and sends out decrypted contents  1503 . Display apparatus  1504  displays decrypted contents  1503 .  
      In this way, this viewing control apparatus can realize viewing control that allows contents delivered on a network and encrypted using one key to be viewed on condition of viewing a latest advertisement.  
      (Sixteenth Embodiment)  
      A sixteenth embodiment of the present invention will explain a viewing control apparatus that can safely send and receive a decryption key for contents encrypted using one key.  
      Here, this embodiment assumes a mode in which an advertisement issuing site delivers contents to a user who has viewed a latest advertisement on networks and allows the user to safely acquire a contents decryption key from the advertisement issuing site at this time.  
      As shown in  FIG. 25 , in this apparatus, advertisement issuing site  1601  that issues key Ks Contents for viewing contents stores key Kw  16011  for encrypting key Ks ite for advertisement issuing sites, generates Ks ite information  16012  by encrypting key Ks ite using key Kw  16011 , encrypts key Ks Contents for viewing contents using key Ks ite and generates Ks Contents information  2  ( 16013 ).  
      On the other hand, in addition to EMM  16021 , key Kw  16022  and EMM updating section  16023 , secure module  1602  is provided with Ks ite extraction section  16025  that decrypts Ks ite information  16012  using key Kw  16022  and extracts key Ks ite and Ks Contents extraction section  16024  that decrypts Ks Contents information  2  ( 16013 ) using key Ks ite extracted by Ks ite extraction section  16025  and extracts key Ks Contents.  
      The operation of this viewing control apparatus will be explained. First, Ks ite extraction section  16025  of secure module  1602  acquires Ks ite information  16012  from advertisement issuing site  1601 , decrypts it using key Kw  16022  and extracts key Ks ite.  
      Next, Ks Contents extraction section  16024  of secure module  1602  acquires Ks Contents information  2  ( 16013 ) of contents to be viewed from advertisement issuing site  1601 , decrypts it using key Ks ite and extracts key Ks Contents.  
      In this way, this viewing control apparatus can safely receive and send a contents key encrypted using one key on networks. The mode of performing viewing control using this extracted key Ks Contents is the same as that in the fifteenth embodiment.  
      (Seventeenth Embodiment)  
      A seventeenth embodiment of the present invention will explain a viewing control apparatus that is capable of performing smoothly viewing control even when randomly viewing stored contents by pausing the contents or rewinding part thereof.  
      Here, the insertion points of an advertisement are supposed to be set every 30 minutes, an advertisement is inserted at the beginning of contents, 30 minutes after the beginning, 1 hour after the beginning and 1 hour and half after the beginning. Furthermore, an expiration date of contents viewing is also supposed to be set to 30 minutes in an EMM update request of the advertisement.  
      In this case, it is possible to view contents until the time at which the next advertisement is inserted by viewing an advertisement, and therefore it is possible to view up to the end of the contents if the advertisement and contents are reproduced sequentially at a normal speed from the advertisement at the beginning without any problem.  
      However, if a pause or slow replay is performed during reproduction of the contents, the next advertisement is not reproduced and viewing of the contents is suspended even after the expiration date of contents viewing is past.  
      The viewing control apparatus in this embodiment can avoid such a situation.  
      As shown in  FIG. 26 , in this apparatus, in addition to encrypted contents  17012 , ECM  17013 , advertisement-related information  17014  (see the seventh embodiment), advertisement  17011  including EMM update request  170111  that is inserted at each insertion point, storage/reproduction apparatus  1701  is provided with advertisement reproduction control section  17015  that controls reproduction of advertisements in order of the description in advertisement-related information  17014  when contents are reproduced. The rest of the configuration is the same as that in the first embodiment ( FIG. 1 ).  
      The operation of this viewing control apparatus will be explained. First, when reproducing contents, storage/reproduction apparatus  1701  reproduces advertisement  17011  (first advertisement  17011  described in advertisement-related information  17014 ) including EMM update request  170111  and encrypted contents  17012 . At that time, ECM  17013  synchronized with encrypted contents  17012  is also reproduced. Advertisement  17011  is displayed on display apparatus  1706 .  
      The next advertisement is not reproduced even when the time during which viewing is allowed and secured by the reproduced advertisement is past (such a state occurs when contents are reproduced at random), advertisement reproduction control section  17015  stops the reproduction of encrypted contents  17012  and ECM  17013 , reproduces next advertisement  17011  described in the advertisement-related information  17014  and then restarts the reproduction of encrypted contents  17012  and ECM  17013 .  
      The operation of secure module  1702  is the same as that of the first embodiment. Under the control of advertisement reproduction control section  17015 , advertisement  17011  is reproduced according to a schedule described in advertisement-related information  17014 , and therefore even when contents are reproduced randomly, viewing of the contents continues without any interruption.  
      In this way, this viewing control apparatus can realize viewing control without any interruption of viewing of contents even when contents are viewed randomly.  
      (Eighteenth Embodiment)  
      An eighteenth embodiment of the present invention will explain a viewing control apparatus that performs viewing control so that a plurality of advertisements assigned to contents are viewed impartially even when contents are viewed randomly.  
      When contents are viewed randomly, if a plurality of advertisements assigned to the contents are sequentially reproduced according to a schedule described in advertisement-related information, a high-numbered advertisement in order of viewing has fewer opportunities to be reproduced than a low-numbered advertisement. Returning to the example shown in the seventeenth embodiment, the probability that an advertisement to be inserted one hour and a half after the beginning may be reproduced is lower than the probability that an advertisement to be inserted after  30  minutes may be reproduced.  
      In order to eliminate such unfairness, the viewing control apparatus of this embodiment is designed to reproduce an advertisement to be inserted immediately before the location of contents to be reproduced when the time at which the advertisement is reproduced comes while contents are being reproduced randomly.  
      As shown in  FIG. 27 , in this apparatus, storage/reproduction apparatus  1801  is provided with encrypted contents  18012  obtained by dividing one content into units in which an advertisement is inserted, ECM  18013  divided in accordance with the respective encrypted contents  18012 , a plurality of advertisements  18011  including EMM update request  180111  and inserted at respective insertion points, advertisement-related information  18014  that includes information about an advertisement list (including the correspondence between points at which advertisements are inserted in contents and the advertisements to be viewed at those points) and advertisement reproduction control section  18015  that references advertisement-related information  18014  when advertisement  18011  is reproduced, selects advertisement  18011  to be reproduced immediately before the encrypted contents  18012  to be reproduced and controls the reproduction of the advertisement. The rest of the configuration is the same as that of the first embodiment ( FIG. 1 ).  
      The operation of this viewing control apparatus will be explained. First, when reproducing contents, storage/reproduction apparatus  1801  reproduces advertisement  18011  including EMM update request  180111  (advertisement  18011  selected by the advertisement reproduction control section  18015  as one to be reproduced immediately before the encrypted contents  18012  to be reproduced with reference to advertisement-related information  18014 ) and encrypted contents  18012 . At that time, ECM  18013  synchronized with the encrypted contents  18012  is also reproduced. Advertisement  18011  is displayed on display apparatus  1806 .  
      Note that when the next advertisement is not reproduced even when the time secured by the reproduced advertisement and during which viewing is allowed is past (such a situation occurs when contents are reproduced at random), advertisement reproduction control section  18015  stops the reproduction of encrypted contents  18012  and ECM  18013 , references advertisement-related information  18014 , selects advertisement  18011  to be reproduced immediately before the encrypted contents  18012  to be reproduced, reproduces advertisement  18011  thereof and then restarts the reproduction of encrypted contents  18012  and ECM  18013 .  
      The operation of the secure module  1802  is the same as that of the first embodiment.  
      Even when contents are reproduced at random, this apparatus reproduces advertisement  18011  under the control of advertisement reproduction control section  18015  so as not to interrupt viewing of contents. Since the advertisement reproduced at this time is supposed to be inserted immediately before encrypted contents  18012  to be reproduced, there will be no difference in the number of opportunities for reproduction associated with the order in which advertisements are inserted.  
      In this way, even when contents to which a plurality of advertisements are assigned are viewed at random, this viewing control apparatus allows advertisements to be viewed impartially.  
      Note that if information stored in the reproduction apparatus of each embodiment is stored in a recording medium such as DVD, it is possible to perform viewing control of contents on condition of viewing an advertisement by reproducing the DVD. For example, by recording encrypted contents, a key to decrypt the contents, advertisement and information about an expiration date until which viewing of the contents is allowed when the advertisement is reproduced and viewed in a recording medium or by recording the advertisement-related information indicating the location of the latest advertisement to be acquired when the expiration date is past, the latest advertisement is viewed every time contents are reproduced. For this reason, this recording medium can serve as new advertisement means.  
      As is clear from the above described explanations, the foregoing viewing control apparatuses are capable of performing viewing control of contents so that contents can be viewed when an advertisement is viewed. For this reason, the viewer can view contents free of charge and the viewer views the advertisement with certainty. Furthermore, since an expiration date is set for viewing of contents which is allowed by viewing an advertisement, it is necessary to view the latest advertisement so that the time points at which contents are viewed are included within the expiration date. As a result, viewing of the advertisement is conducted in consonance with the expectation of the advertiser. Furthermore, the contents producer can obtain an advertisement fee targeted at contents produced in the past.  
      Furthermore, it is possible to perform viewing control so as not to allow the viewer to view contents unless the viewer views the advertisement from beginning to end and ensure the advertisement is viewed.  
      As described above, an aspect of the viewing control apparatus of the present invention is a viewing control apparatus constructed so as to store contents identification information and viewing condition information indicating a viewing expiration date of the contents in a processing module, update, when an advertisement associated with viewing condition update information for updating the viewing condition information is reproduced, the viewing condition information stored in the processing module through an updating section based on the viewing condition update information and control reproduction of the contents based on the viewing condition information.  
      This configuration allows the viewer to view the contents free of charge and thereby ensures that the viewer sees the advertisement. Furthermore, since an expiration date is set for viewing of contents, which is allowed by viewing an advertisement, a latest advertisement needs to be viewed so that the viewing time point of the contents is included within the expiration date. As a result, the advertisement is viewed as the advertisers expect. Furthermore, the contents producer can earn an advertisement fee from the contents produced in the past.  
      Furthermore, the processing module is constructed of a secure module.  
      This configuration allows the viewing condition to be stored or updated securely.  
      Furthermore, the expiration date of the contents is specified with an absolute time or relative time.  
      This configuration allows the expiration date of the contents to be specified with an absolute time or relative time.  
      Furthermore, an expiration date of the contents indicated with an absolute time is generated based on the expiration date of the contents indicated with a relative time using an arbitrary time point between an advertisement viewing start time and advertisement viewing end time or a time at which the advertisement is acquired as a reference time.  
      This configuration allows specification with a relative time to be converted to specification with an absolute time.  
      Furthermore, the viewing condition update information is configured to include advertisement-related information indicating an expiration date of an associated advertisement and a source of a latest advertisement to be acquired at a time at which the expiration date is past.  
      This configuration allows the latest advertisement information to be acquired and delivered.  
      Furthermore, the contents or the advertisement are acquired via broadcasting, communication or a recording medium.  
      This configuration allows the contents or advertisement to be acquired via broadcasting, communication or a recording medium.  
      Furthermore, the contents or the advertisement are configured to be stored in advance.  
      This configuration allows the contents or the advertisement to be stored in advance and reproduced.  
      Furthermore, the contents, the viewing condition update information or the viewing condition information is encrypted.  
      This configuration allows the contents, the viewing condition update information or the viewing condition information to be saved securely.  
      Furthermore, it is configured that a first key encrypted using a common key is output to a processing module when reproduction of the advertisement is started and the viewing condition update information encrypted using the first key is output to the processing module when the reproduction of the advertisement is completed and the processing module decrypts the first key using the common key and decrypts the viewing condition update information using the first key to update the viewing condition information.  
      This configuration provides viewing control so that contents cannot be viewed without viewing an advertisement from beginning to end and ensures the advertisement is viewed.  
      Furthermore, it is configured that when a lapse of time after the first key is received by the processing module until the viewing condition update information is received is different from the original reproduction display time of the advertisement, the viewing condition information is not updated.  
      This configuration allows the time interval between the times at which the start and end of the advertisement are viewed to be measured, and can thereby prevent fast forwarding or the like of the advertisement.  
      Furthermore, it is configured that the first key encrypted using the common key is output to the processing module when reproduction of the advertisement is started, and from then on, a new key is encrypted using key sent immediately before and output to the processing module every time the reproduction of the advertisement advances by a predetermined amount and the viewing condition update information encrypted using key sent immediately before is output to the processing module when the reproduction of the advertisement is completed, the processing module decrypts and reproduces key sent sequentially and decrypts the viewing condition update information using key sent before to update the viewing condition information.  
      Because of this configuration, it is not possible to acquire a key for viewing contents unless all of a plurality of points within the advertisement are viewed without fast forwarding or the like. This ensures that fast forwarding or the like of the advertisement is prevented and ensures that the advertisement is viewed.  
      Furthermore, when a lapse of time after each key is received by the processing module until the next key is received and a lapse of time after the last key is received until the viewing condition update information is received are different from the time required to advance the reproduction of the advertisement by a predetermined amount, the viewing condition information is not updated.  
      This configuration does not allow key for viewing contents to be obtained unless all of a plurality of points within the advertisement are viewed without fast forwarding or the like. This ensures that fast forwarding or the like of the advertisement is prevented and ensures that the advertisement is viewed.  
      Furthermore, when the contents are copied, an advertisement which allows the contents to be viewed is copied together.  
      When the copied contents are viewed, this configuration provides similar viewing control on condition of viewing the advertisement.  
      Furthermore, the above described configuration provides the viewing control apparatus according to claim  1 , wherein the viewing condition information or the viewing information update information is associated with a group of contents.  
      This configuration allows management of viewing control of contents to be performed by grouping the contents.  
      Furthermore, the above described configuration provides the viewing control apparatus according to claim  1 , wherein when the contents are reproduced, an advertisement which allows viewing of the contents is reproduced before the contents.  
      According to this configuration, it is possible to reproduce an advertisement which allows viewing of the contents before the contents.  
      This application is based on Japanese Patent Application No. 2003-174785 filed on Jun. 19, 2003 and Japanese Patent Application No. 2004-177584 filed on Jun. 15, 2004, entire content of which is expressly incorporated by reference herein.  
     INDUSTRIAL APPLICABILITY  
      The viewing control apparatus, viewing control program and secure device according to the present invention can perform contents viewing control so that contents can be viewed when an advertisement is viewed and thereby produce an effect of ensuring that the viewer views the advertisement in order to view the contents free of charge and are suitable for use in a viewing control apparatus, viewing control program and secure device for controlling viewing of broadcasting contents or stored contents.