Patent Publication Number: US-7725876-B2

Title: Original contents creation apparatus, derived contents creation apparatus, derived contents using apparatus, original contents creation method, derived contents creation method, and derived contents using method and verification method

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application P2004-169003 filed on Jun. 7, 2004; the entire contents of which are incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an original contents creation apparatus, a derived contents creation apparatus, a derived contents using apparatus, an original contents creation method, a derived contents creation method, and derived contents using method and verification method. 
     2. Description of the Related Art 
     In a contents distribution system on the Internet, it is necessary to protect contents from unauthorized use and tamper. As such a technology for protecting the contents, for example, disclosed has been a technology for protecting the contents by integrating the contents and a use rule together as a package, and then to make a digital signature on the package and encode the package concerned (for example, refer to Japanese Patent Publication No. H10-512074 (published in 1998)). However, such an existing contents protection technology is on the premise of end-to-end protection, and has eliminated an addition of secondary contents on a distribution path between an original contents provider and an end user. 
     In the field of broadcasting, a model is established, in which a local station purchases original contents provided by a key station, and inserts an advertisement suitable for a region covered by the local station. This model has a merit for the key station in that it becomes easy to recover an expense of producing the original contents by effective use thereof, and has a merit for the local station in that an increase of advertisement income can be expected by redistributing the high-quality contents produced by the key station. 
     It is conceivable that a similar model to the above is realized in contents distribution on the Internet to expand a use range of the original contents, thus making it possible to contribute to an expansion of profit resources of an original contents provider and to a service improvement of a secondary provider. A contents distribution system that permits the secondary provider to add the secondary contents is hereinafter referred to as a “derived contents distribution system”. 
     As an aspect of realizing the derived contents distribution system, there is a model of completely entrusting the secondary provider to add the secondary contents and protect the derived contents. In this model, the secondary provider acquires the original contents through a safe communication path, adds the secondary contents thereto, and then gives an appropriate protection to derived contents thus formed, and distributes the contents concerned to the end user. This model is premised on a complete relationship of trust between the original contents provider and the secondary contents provider, and is established only when it is reliable that the secondary provider abides by a condition to be met by the secondary contents and a condition to protect the original contents, and so on. 
     From a viewpoint of expanding the use of the contents, desirable is a derived contents distribution system that permits the insertion of the secondary contents not only by the specific reliable secondary provider but also by any number of secondary providers. However, establishing the relationship of trust, which is as described above, with any number of secondary providers lacks in scalability. Moreover, when unauthorized derived contents or contents that are not appropriately protected are distributed, it becomes difficult to pursue a secondary provider causing such an inappropriate distribution. 
     Meanwhile, the secondary provider requires a function to prevent the secondary contents from being removed from the derived contents in an unauthorized manner. For example, such a situation must be avoided, where advertisement contents and a sponsor name, which are added as the secondary contents, are deleted on the distribution path, and the user can watch and listen to only the original contents. 
     Further, in regard to the contents, there is disclosed a method for setting a limitation rule to add a control over the use of the contents (for example, refer to Japanese Patent No. 3485911). However, in this method, it is difficult to perform a correctness verification of the modified contents (the secondary contents) and the limitation rule. 
     SUMMARY OF THE INVENTION 
     In this connection, considering the above-described subject, it is an object of the present invention to provide an original contents creation apparatus, a derived contents creation apparatus, a derived contents using apparatus, an original contents creation method, a derived contents creation method, and derived contents using method and verification method, which realize the protection of the original contents and the derived contents in derived contents distribution by any number of secondary providers. 
     In order to achieve the above-described object, a first feature of the present invention is summarized to be an original contents creation apparatus for creating original contents, including: (A) a limitation rule acquisition unit configured to acquire a limitation rule of a case of inserting additional secondary contents into the original contents; (B) a joining unit configured to join the limitation rule and a first operation rule to the original contents, the first operation rule defining an operation of a case of having detected an insertion of secondary contents violating the limitation rule; and (C) a signature unit configured to give an electronic signature to the original contents to which the limitation rule and the first operation rule are joined. 
     According to the contents creation apparatus in accordance with the first feature, the limitation rule is joined to the original contents, thus making it possible to realize a protection of the original contents and the derived contents in the derived contents distribution by any number of secondary providers. 
     Moreover, the contents creation apparatus according to the first feature may further include: a first receiving unit configured to receive a parameter from an apparatus for inserting the secondary contents into the original contents, the parameter being necessary for correctness verification of derived contents into which the secondary contents are inserted, wherein the joining unit may further join the parameter to the original contents. According to this contents creation apparatus, the parameter can be prevented from being tampered after the derived contents are crated. Hence, the correctness verification of the derived contents can be ensured more. 
     Furthermore, in the contents creation apparatus according to the first feature, the original contents may contain a placeholder for designating an insertion place of the secondary contents, and the original contents creation apparatus may further include: a second receiving unit configured to receive a placeholder request containing identification information of the placeholder from the apparatus for inserting the secondary contents into the original contents. According to this contents creation apparatus, the apparatus (secondary provider) for inserting the secondary contents can request a specific placeholder. 
     A second feature of the present invention is summarized to be a derived contents creation apparatus for inserting additional secondary contents into original contents, thereby creating derived contents, including: (A) a limitation rule extraction unit configured to extract a limitation rule of a case of inserting the secondary contents, the limitation rule being contained in the original contents; (B) a secondary contents insertion unit configured to insert the secondary contents into the original contents when the secondary contents fit to the limitation rule; and (C) a derived contents signature unit configured to give an electronic signature to the derived contents. 
     According to the derived contents creation apparatus in accordance with the second feature, the secondary contents that fit to the limitation rule are inserted, thus making it possible to realize the protection of the original contents and the derived contents in the derived contents distribution by any number of secondary providers. Moreover, the electronic signature is given to the derived contents, thus making it possible to detect the tamper to the secondary contents. 
     Moreover, the derived contents creation apparatus according to the second feature may further include: a first transmission unit configured to transmit, to an apparatus for creating the original contents, a parameter necessary for correctness verification of the derived contents into which the secondary contents are inserted, wherein the derived contents signature unit may give the electronic signature by using an algorithm and a signature key which correspond to the parameter. According to this derived contents creation apparatus, the parameter can be contained in the signature for the original contents, and accordingly, the parameter can be protected from the tamper. Therefore, the correctness verification of the derived contents containing the secondary contents can be ensured more. 
     Furthermore, the derived contents creation apparatus according to the second feature may further include: a second transmission unit configured to designate, to the original contents, a placeholder for inserting the secondary contents thereinto, and transmit a placeholder request containing identification information of the placeholder to the apparatus for creating the original contents, wherein the secondary contents insertion unit may insert the secondary contents into the placeholder. According to this derived contents creation apparatus, the place where the secondary contents are inserted into the original contents can be requested beforehand. 
     A third feature of the present invention is summarized to be a derived contents using apparatus for using derived contents formed by inserting additional secondary contents into original contents, including: (A) a derived contents using unit configured to decide processing of the derived contents based on a first verification result of an electronic signature by an apparatus that has created the original contents, a second verification result of an electronic signature by an apparatus that has inserted the secondary contents, and a fitness result of the secondary contents to a limitation rule of a case of inserting the secondary contents, the limitation rule being contained in the original contents. Here, the “derived contents using apparatus” refers to an apparatus for using the derived contents in some way, such as copying the derived contents, as well as an apparatus for replaying the derived contents. 
     According to the contents using apparatus in accordance with the third feature, the processing is performed based on the verification results of the signatures and the fitness result with respect to the limitation rule, thus making it possible to realize the protection of the original contents and the derived contents in the derived contents distribution by any number of secondary providers. Specifically, the origins and correctnesses of the original contents and the derived contents can be verified. 
     Moreover, the derived contents using unit of the derived contents using apparatus according to the third feature: may interrupt replay processing of the derived contents when either the first verification result or the second verification result is a failure; may process the derived contents according to a first operation rule defining an operation of a case of having detected an insertion of secondary contents violating the limitation rule when the secondary contents do not fit to the limitation rule, the first operation rule being described in the original contents; and may use the derived contents when the first verification result and the second verification result are successes and the secondary contents fit to the limitation rule. According to this contents using apparatus, in the case of having received unauthorized contents or tampered contents, use thereof can be stopped. Moreover, an appropriate operation is performed according to the operation rules, and accordingly, a user of the contents can be protected from the unauthorized contents. Moreover, the unauthorized derived contents can be prevented from being used, thus making it possible to protect the original contents. 
     A fourth feature of the present invention is summarized to be an original contents creation method for creating original contents, including: (A) acquiring a limitation rule of a case of inserting additional secondary contents into the original contents; (B) joining the limitation rule and a first operation rule to the original contents, the first operation rule defining an operation of a case of having detected an insertion of secondary contents violating the limitation rule; and (C) giving an electronic signature to the original contents to which the limitation rule and the first operation rule are joined. 
     According to the contents creation method in accordance with the fourth feature, the limitation rule is joined to the original contents, thus making it possible to realize the protection of the original contents and the derived contents in the derived contents distribution by any number of secondary providers. 
     A fifth feature of the present invention is summarized to be a derived contents creation method for inserting additional secondary contents into original contents, thereby creating derived contents, including: (A) extracting a limitation rule of a case of inserting the secondary contents, the limitation rule being contained in the original contents; (B) inserting the secondary contents into the original contents when the secondary contents fit to the limitation rule; and (C) giving an electronic signature to the derived contents. 
     According to the derived contents creation method in accordance with the fifth feature, the secondary contents that fit to the limitation rule are inserted, thus making it possible to realize the protection of the original contents and the derived contents in the derived contents distribution by any number of secondary providers. Moreover, the electronic signature is given to the derived contents, thus making it possible to detect the tamper to the secondary contents. 
     A sixth feature of the present invention is summarized to be a derived contents using method for using derived contents formed by inserting additional secondary contents into original contents, including: (A) deciding processing of the derived contents based on a first verification result of an electronic signature by an apparatus that has created the original contents, a second verification result of an electronic signature by an apparatus that has inserted the secondary contents, and a fitness result of the secondary contents to a limitation rule of a case of inserting the secondary contents, the limitation rule being contained in the original contents. 
     According to the contents using method in accordance with the sixth feature, the processing is performed based on the verification results of the signatures and the fitness result with respect to the limitation rule, thus making it possible to realize the protection of the original contents and the derived contents in the derived contents distribution by any number of secondary providers. Specifically, the origins and correctnesses of the original contents and the derived contents can be verified. 
     A seventh feature of the present invention is summarized to be a verification method for verifying derived contents formed by inserting additional secondary contents into original contents, including: (A) acquiring a limitation rule of a case of inserting the additional secondary contents into the original contents; (B) joining the limitation rule and a first operation rule to the original contents, the first operation rule defining an operation of a case of having detected an insertion of secondary contents violating the limitation rule; (C) giving a first electronic signature to the original contents to which the limitation rule and the first operation rule are joined; (D) extracting the limitation rule contained in the original contents; (E) inserting the secondary contents into the original contents when the secondary contents fit to the limitation rule; (F) giving a second electronic signature to the derived contents; and (G) deciding processing of the derived contents based on a verification result of the first electronic signature, a verification result of the second electronic signature, and a fitness result of the secondary contents to the limitation rule. 
     According to the verification method in accordance with the seventh feature, the protection of the original contents and the derived contents can be realized in the derived contents distribution by any number of secondary providers. 
     According to the present invention, there can be provided the original contents creation apparatus, the derived contents creation apparatus, the derived contents using apparatus, the original contents creation method, the derived contents creation method, and the derived contents using method and verification method, which realize the protection of the original contents and the derived contents in the derived contents distribution by any number of secondary providers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration block diagram of a derived contents distribution system according to a first embodiment. 
         FIG. 2  is a configuration block diagram of an original contents creation apparatus according to the first embodiment. 
         FIG. 3  is a flowchart showing an original contents creation method according to the first embodiment. 
         FIG. 4  is an example of original contents according to the first embodiment. 
         FIG. 5  is an example of a secondary contents limitation rule according to the first embodiment. 
         FIG. 6  is an example of derived contents added with an electronic signature according to the first embodiment. 
         FIG. 7  is a configuration block diagram according to a derived contents creation apparatus according to the first embodiment. 
         FIG. 8  is a flowchart showing a derived contents creation method according to the first embodiment. 
         FIG. 9  is an example of secondary contents according to the first embodiment. 
         FIG. 10  is an example of derived contents according to the first embodiment. 
         FIG. 11  is an example of the derived contents added with a signature according to the first embodiment (No. 1). 
         FIG. 12  is an example of the derived contents added with the signature according to the first embodiment (No. 2). 
         FIG. 13  is a configuration block diagram of a derived contents replay apparatus according to the first embodiment. 
         FIG. 14  is a flowchart showing a derived contents replay method according to the first embodiment. 
         FIG. 15  is a configuration block diagram of a derived contents distribution system according to a second embodiment. 
         FIG. 16  is a configuration block diagram of an original contents creation apparatus according to the second embodiment. 
         FIG. 17  is a flowchart showing an original contents creation method according to the second embodiment. 
         FIG. 18  is an example of original contents according to the second embodiment. 
         FIG. 19  is an example of a secondary contents limitation rule according to the second embodiment. 
         FIG. 20  is an example of derived contents added with an electronic signature according to the second embodiment. 
         FIG. 21  is a configuration block diagram of a derived contents creation apparatus according to the second embodiment. 
         FIG. 22  is a flowchart showing a derived contents creation method according to the second embodiment. 
         FIG. 23  is an example of secondary contents according to the second embodiment. 
         FIG. 24  is an example of derived contents according to the second embodiment. 
         FIG. 25  is an example of the derived contents added with a signature according to the second embodiment. 
         FIG. 26  is a configuration block diagram of a derived contents replay apparatus according to the second embodiment. 
         FIG. 27  is a flowchart showing a derived contents replay method according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Next, embodiments of the present invention will be described with reference to the drawings. In the description below with reference to the drawings, the same or similar numerals are assigned to the same or similar portions. It should be noted that the drawings are schematic. 
     First and second embodiments describe a derived contents distribution system that realizes protection of original contents and derived contents by an original contents creation apparatus (original provider), a derived contents creation apparatus (secondary provider), and a derived contents replay apparatus. Here, the “original contents” are contents provided by the original contents provider and the like, the “secondary contents” are additional contents such as an advertisement inserted into the original contents by the secondary provider, and the “derived contents” are contents in a state where the secondary contents are inserted into the original contents. 
     First Embodiment 
     (Derived Contents Distribution System) 
     As shown in  FIG. 1 , the derived contents distribution system according to the embodiments of the present invention includes an original contents creation apparatus  10 , a derived contents creation apparatus  20 , and derived contents replay apparatus  30 . The original contents creation apparatus  10  creates the original contents, and transmits the created original contents to the derived contents creation apparatus  20 . The derived contents creation apparatus  20  inserts the secondary contents into the original contents, and transmits the derived contents outputted therefrom to the derived contents replay apparatus  30 . The derived contents replay apparatus  30  replays the received derived contents. 
     The original contents are transmitted through a communication network (Internet or the like)  40   a  or a storage medium  50   a  (compact disc, memory card, flexible disk or the like). In a similar way, the derived contents are transmitted through a communication network (Internet or the like)  40   b  or a storage medium  50   b  (compact disc, memory card, flexible disk or the like). 
     Next, description will be made of detailed configurations and operations of the original contents creation apparatus  10 , the derived contents creation apparatus  20  and the derived contents replay apparatus  30 . 
     (Original Contents Creation Apparatus and Method) 
     As shown in  FIG. 2 , the original contents creation apparatus  10  includes an original contents acquisition unit  11 , a secondary contents limitation rule acquisition unit  12 , and a joining/signature unit  13 , and is connected to an original contents storage unit  60  and a secondary contents limitation rule storage unit  70 . 
     The original contents storage unit  60  stores the original contents. The original contents may be media data including encoded audio and video information, or information (metadata) for the media data. The description below will be made while assuming that the original contents are treated as the metadata; however, a similar protection technology may also be applied to the media data.  FIG. 4  is, as an example of the original contents  111 , metadata described by using a scene description language SMIL (synchronized multimedia integration language, refer to W3C SMIL2.0, http://www.w3.org/TR/smil20/) for multimedia contents. In this metadata, access information to the media data and arrangement information of the media data when being replayed are described. 
     The secondary contents limitation rule storage unit  70  stores a limitation rule of the case of inserting the secondary contents into the original contents.  FIG. 5  shows an example of a limitation rule  121  described by using XACML (refer to OASIS XACML, http://www.oasis-open.org/committees/tc_home.php/wg_abbrev=xacml), which is an access control markup language to an XML base.  FIG. 5  shows a rule to add a second par element under command of a first seq element to the metadata shown in  FIG. 4  and to enable a 20-second video streaming accessible according to the RTSP to be added thereinto. Note that, by defining appropriate attribute names, it is possible to designate not only a media type, a replay time and protocol for use but also attribute information such as an image size and an age restriction, as feature quantities to be met by the secondary contents. 
     The original contents acquisition unit  11  acquires the original contents from the original contents storage unit  60 . 
     The secondary contents limitation rule acquisition unit  12  (limitation rule acquiring means) acquires the limitation rule from the secondary contents limitation rule storage unit  70 . Moreover, the secondary contents limitation rule acquisition unit  12  acquires a first operation rule that defines an operation of the case where the secondary contents violate the limitation rule. Furthermore, the secondary contents limitation rule acquisition unit  12  acquires a second operation rule that defines an operation of the case where the insertion of the secondary contents violating the limitation rule has not been detected. 
     The joining/signature unit  13  (joining means and signature means) joins the metadata and the secondary content limitation rule, which are described above, to each other, and gives an electronic signature thereto. In  FIG. 6 , a smil element of the original contents  111  and a Policy element of the limitation rule  121  are continuously joined to each other, and an XML signature is given to an XML document formed by such joining (refer to W3C XML-Signature, http://www.w3.org/TR/xmldsig-core). 
     Note that, though the signature is given to the document formed by continuously joining the limitation data to the metadata in this embodiment, only a hash value of the limitation rule may be contained in a signature element (signedinfo) for the metadata, and an entity of the limitation rule may be distributed separately from the metadata. 
     Next, an original contents creation method will be described by using  FIG. 3 . 
     (A) First, in Step S 101 , the original contents acquisition unit  11  acquires the original contents from the original contents storage unit  60 . Meanwhile, in Step S 102 , the secondary contents limitation rule acquisition unit  12  acquires the secondary contents limitation rule from the secondary contents limitation rule storage unit  70 . Moreover, the secondary contents limitation rule acquisition unit  12  acquires the first operation rule that defines the operation of the case where the secondary contents violate the limitation rule and a second operation rule of the case where the secondary contents do not violate the limitation rule. 
     (B) Next, in Step S 103 , the joining/signature unit  13  joins the original contents and the secondary contents limitation rule. Specifically, as shown in  FIG. 6 , the joining/signature unit  13  continuously joins the smil element of the original contents  111  and the Policy element of the limitation rule  121 , and joins the first operation rule (Response element) and the second operation rule (Response element) to each other. 
     (C) Next, in Step S 104 , the joining/signature unit  13  gives the signature to the original contents to which the secondary contents limitation rule is joined. For example, as shown in  FIG. 6 , to the original contents, the joining/signature unit  13  gives hash values of the limitation rule, the first operation rule, the second operation rule and the metadata (original contents), and gives a signature value and verification key information of the original contents creation apparatus. 
     (D) Then, in Step S 105 , the joining/signature unit  13  outputs the original contents added with the electronic signature. The outputted original contents added with the electronic signature are transmitted to the derived contents creation apparatus  20 . 
     (Derived Contents Creation Apparatus and Method) 
     As shown in  FIG. 7 , the derived contents creation apparatus  20  includes an original contents acquisition unit  21 , a secondary contents acquisition unit  22 , a limitation rule extraction unit  23 , a limitation rule evaluation unit  24 , a secondary contents insertion unit  25 , and a derived contents signature unit  26 , and is connected to a secondary contents storage unit  80 . 
     The secondary contents storage unit  80  stores secondary contents as shown in  FIG. 9 . 
     The original contents acquisition unit  21  acquires the original contents  131  added with an electronic signature from the original contents creation apparatus  10  through the network  40   a  or the storage medium  50   a.    
     The secondary contents acquisition unit  22  acquires the secondary contents  221  to be inserted into the original contents  131  added with the electronic signature from the secondary contents storage unit  80 . Here, when the original contents  131  added with the electronic signature are the metadata, the secondary contents to be inserted are also metadata describing the information of the media data. Note that, in the case of using the media data for the original contents, the secondary contents are also media data. This case is also realizable by applying a protection format similar to that of the first embodiment. 
     The limitation rule extraction unit  23  (limitation rule extracting means) extracts the secondary contents limitation rule  121  from the original contents  131  with the electronic signature, and inputs the rule concerned to the limitation rule evaluation unit  24 . Moreover, the limitation rule extraction unit  23  extracts the first operation rule and the second operation rule from the original contents  131  added with the electronic signature, and inputs the rules concerned to the limitation rule evaluation unit  24 . 
     The limitation rule evaluation unit  24  extracts the feature quantity of the secondary contents from the secondary contents  221 , and determines whether or not the secondary contents  221  fit to the secondary contents limitation rule  121 . When the secondary contents do not fit to the limitation rule, for example, the limitation rule evaluation unit  24  outputs a repudiation notice to the secondary contents insertion unit  25  according to the first operation rule, and makes the secondary contents insertion unit  25  stop processing for inserting the secondary contents  221  into the original contents  131  added with the electronic signature. Meanwhile, when the secondary contents fit to the limitation rule, for example, the limitation rule evaluation unit  24  issues a notice on permission to insert the secondary contents  221  into the original contents  131  added with the electronic signature to the secondary contents insertion unit  25  according to the second operation rule. 
     Upon receiving the notice on the insertion permission, the secondary contents insertion unit  25  (secondary contents inserting means) inserts the derived contents  221  into the original contents  131 , and outputs derived contents  251  as shown in  FIG. 10 . 
     The derived contents signature unit  26  (derived contents signature means) gives the electronic signature to the derived contents  221 , and outputs derived contents  261  added with the electronic signature, which are as shown in  FIG. 11 . Moreover, the derived contents signature unit  26  may give the electronic signature after describing a third operation rule that defines an operation of the case where an unauthorized deletion of the secondary contents has been detected and a fourth operation rule that defines an operation of the case where the unauthorized deletion of the secondary contents has not been detected. 
     Note that, though not essential, it is also possible for each of the limitation rule extraction unit  23  and the limitation rule evaluation unit  24  to include an appropriate protection mechanism for the purpose of protecting the contents from an unauthorized intervention by a malicious person or program. For example, the above-described processing is performed by a server apparatus physically isolated from an outsider, thus making it possible to protect the contents from the malicious outsider. Moreover, communications between a memory to be used by the respective processing units and the respective processing units are protected by means of an encryption technology, thus making it possible to protect the contents from the malicious program such as a worm and a virus. 
     Moreover, such a configuration is also possible, in which the limitation rule extraction unit  23  and the limitation rule evaluation unit  24  are arranged in another server apparatus protected appropriately. In this case, it is necessary to protect a connection between this server apparatus and the derived contents creation apparatus  20  by means of the encryption technology. 
     Next, a derived contents creation method will be described by using  FIG. 8 . 
     (A) First, in Step S 201 , the original contents acquisition unit  21  acquires the original contents  131  added with the electronic signature from the original contents creation apparatus  10  through the network  40   a  or the storage medium  50   a . Then, in Step S 202 , the limitation rule extraction unit  23  extracts the secondary contents limitation rule  121 , the first operation rule and the second operation rule from the original contents  131  added with the electronic signature, and inputs the rules concerned to the limitation rule evaluation unit  24 . 
     (B) Meanwhile, in Step S 203 , the secondary contents acquisition unit  22  acquires the secondary contents  221  from the secondary contents storage unit  80 . 
     (C) In Step S 204 , the limitation rule evaluation unit  24  extracts the feature quantity of the secondary contents from the acquired secondary contents  221 , and determines whether or not the secondary contents fit to the secondary contents limitation rule  121 . When the secondary contents do not fit to the limitation rule, the processing proceeds to Step S 205 , where, for example, the limitation rule evaluation unit  24  outputs the repudiation notice to the secondary contents insertion unit  25  according to the first operation rule, and makes the secondary contents insertion unit  25  stop the processing for inserting the secondary contents  221  into the original contents  131  added with the electronic signature. Meanwhile, when the secondary contents fit to the limitation rule, the processing proceeds to Step S 206 , where, for example, the limitation rule evaluation unit  24  issues the notice on permission to insert the secondary contents  221  into the original contents  131  added with the electronic signature to the secondary contents insertion unit  25  according to the second operation rule. 
     (D) In Step S 206 , the secondary contents insertion unit  25  inserts the secondary contents  221  into the original contents  131 , and outputs the derived contents  261 . 
     (E) Next, in Step S 207 , the derived contents signature unit  26  gives the electronic signature to the derived contents  221 . For example, as shown in  FIG. 11 , the derived contents signature unit  26  gives a hash value of the original contents to the derived contents, and gives a signature value and verification key information of the derived contents creation apparatus. 
     (F) Then, the derived contents signature unit  26  outputs the derived contents  261  added with the electronic signature. The outputted derived contents  261  added with the electronic signature are transmitted to the derived contents replay apparatus  30 . 
     Note that, in Step S 207 , as shown in  FIG. 12 , the derived contents signature unit  26  may give the electronic signature after describing the third operation rule that defines the operation of the case where the unauthorized deletion of the secondary contents has been detected and the fourth operation rule that defines the operation of the case where the unauthorized deletion of the secondary contents has not been detected. 
     (Derived Contents Replay Apparatus and Method) 
     As shown in  FIG. 13 , the derived contents replay apparatus  30  includes a derived contents acquisition unit  31 , an original contents signature verification unit  32 , a derived contents signature verification unit  33 , a limitation rule evaluation unit  34 , and a derived contents replay processing unit  35 . 
     The derived contents acquisition unit  31  acquires the derived contents  261  added with the electronic signature from the derived contents creation apparatus  20  through the network  40   b  or the storage medium  50   b.    
     The original contents signature verification unit  32  removes the secondary contents from the derived contents  261  added with the electronic signature, verifies the electronic signature given by the original contents creation apparatus  10 , and issues a notice on a verification result to the derived contents replay processing unit  35 . 
     The derived contents signature verification unit  33  verifies the electronic signature given by the derived contents creation apparatus  20 , and issues a notice on a verification result to the derived contents replay processing unit  35 . 
     The limitation rule evaluation unit  34  determines whether or not the secondary contents  221  contained in the derived contents  261  meet the secondary contents limitation rule  121 , and issues a notice on a result thereof to the derived contents replay processing unit  35 . 
     The derived contents replay processing unit  35  (derived contents using means) performs derived contents replay processing based on the respective results of the signature verifications and the evaluation result of the limitation rule. 
     Specifically, when at least any one of the results of the signature verifications is a failure, the derived contents replay processing unit  35  stops the replay processing immediately, and outputs an appropriate error message. Moreover, when the secondary contents do not fit to the limitation rule, for example, the derived contents replay processing unit  35  stops the replay processing immediately according to the first operation rule contained in the derived contents  261 , and outputs an appropriate error message. 
     Meanwhile, when both results of the signature verifications are successes, and the secondary contents fit to the limitation rule, for example, the derived contents replay processing unit  35  performs the replay processing for the derived contents according to the second operation rule. 
     Note that, in the case of having received the derived contents  262  as shown in  FIG. 12 , in which the third operation rule and the fourth operation rule are contained, the derived contents replay apparatus  30  performs processing according to the third operation rule in the case of having detected the deletion of the secondary contents and according to the fourth operation rule in the case of not having detected the deletion of the secondary contents. 
     Moreover, since the derived contents  261  are metadata in the first embodiment, the derived contents replay processing unit  35  performs acquisition/replay processing of the media data according to the description in the metadata. 
     Moreover, it is necessary to protect the original contents signature verification unit  32 , the derived contents signature verification unit  33 , the limitation rule evaluation unit  34  and the derived contents replay processing unit  35  from the unauthorized intervention by the malicious person or program. The communications between the memory for use in the respective processing units and the respective processing units are protected by means of the encryption technology, thus making it possible to protect the contents from the malicious person or program. 
     Moreover, such a configuration is also possible, in which the above-described components are protected by being mounted on tamper-resistant hardware. 
     Next, a derived contents replay method will be described by using  FIG. 14 . 
     (A) First, in Step S 201 , the derived contents acquisition unit  31  acquires the derived contents  261  added with the electronic signature from the derived contents creation apparatus  20  through the network  40   b  or the storage medium  50   b.    
     (B) Next, in Step S 302 , the original contents signature verification unit  32  verifies the electronic signature given by the original contents creation apparatus  10 , and issues a notice on a result of the verification to the derived contents replay processing unit  35 . In Step S 303 , the derived contents replay processing unit  35  determines whether or not the result of the signature verification is a success. When the result is a success, the processing proceeds to Step S 305 , and when the result is a failure, the processing proceeds to Step S 304 , where the replay processing is stopped immediately, and an appropriate error message is outputted. 
     (C) Next, in Step S 305 , the derived contents signature verification unit  33  verifies the electronic signature given by the derived contents creation apparatus  20 , and issues a notice on a result of the verification to the derived contents replay processing unit  35 . In Step S 306 , the derived contents replay processing unit  35  determines whether or not the result of the signature verification is a success. When the result is a success, the processing proceeds to Step S 307 , and when the result is a failure, the processing proceeds to Step S 304 , where the replay processing is stopped immediately, and an appropriate error message is outputted. 
     (D) Next, in Step S 307 , the derived contents replay processing unit  35  determines whether or not the secondary contents fit to the limitation rule. When the secondary contents do not fit to the limitation rule, the processing proceeds to Step S 304 , where, for example, the replay processing is stopped immediately according to the first operation rule contained in the derived contents  261 , and an appropriate error message is outputted. Meanwhile, when the secondary contents fit to the limitation rule, the processing proceeds to Step S 308 , where, for example, the derived contents replay processing unit  35  performs the replay processing of the derived contents according to the second operation rule. 
     Moreover, the derived contents replay processing unit  35  may determine whether or not the deletion of the secondary contents has been detected, and may perform the processing according to the third operation rule contained in the derived contents  262  (refer to  FIG. 12 ) when the deletion of the secondary contents has been detected, and according to the fourth operation rule contained in the derived contents  262  when the deletion of the secondary contents has not been detected. 
     Note that, in the flowchart of  FIG. 14 , the verification of the electronic signature given by the original contents creation apparatus (Step S 302 ), the verification of the electronic signature given by the derived contents creation apparatus (Step S 305 ), and the verification with respect to the limitation rule (S 307 ), are performed in this order; however, the order is not limited to this, and these verifications may be performed in an arbitrary order. Moreover, the original contents signature verification unit  32  and the derived contents signature verification unit  33  may stop the other processing immediately in the case of failing in the correctness verification of the signature. 
     (Function and Effect) 
     In the derived contents distribution system according to the first embodiment, the limitation rule for the secondary contents is contained in the original contents, thus making it possible to certainly evaluate whether or not the secondary contents are pursuant to the limitation rule in addition to the correctness verification of the original contents in the derived contents creation apparatus  20 . 
     Moreover, according to the derived contents distribution system in accordance with the first embodiment, the limitation rule can be contained in the signature of the original contents. In such a way, it is made possible to protect the limitation rule from the tamper and prevent the unauthorized use of contents. 
     Moreover, the original contents provider can define the operation in response to the detection result of the violation of the limitation rule, and accordingly, it is made possible to deal with the violation on the derived contents replay apparatus  30  side. 
     Moreover, according to the derived contents creation apparatus  20  in accordance with the first embodiment, it can be confirmed whether or not the secondary contents meet the limitation set by the original contents before the creation of the derived contents. Furthermore, the signature is given to the derived contents, thus making it possible to detect the tamper to the secondary contents. 
     Moreover, according to the derived contents replay apparatus  30  in accordance with the first embodiment, the origins and correctnesses of both of the original contents and the secondary contents can be verified. In the case of having received unauthorized contents or tampered contents, the replay can be stopped. Moreover, the original contents creation apparatus  10  performs the appropriate operation according to the operation rule designated by the original contents creation apparatus  10  in response to the verification result whether or not the secondary contents are pursuant to the limitation defined by the original contents creation apparatus  10 . Hence, it is possible to protect the user of the contents from the unauthorized contents. Moreover, the unauthorized derived contents are prevented from being replayed, thus making it possible to protect the original contents. 
     Moreover, according to the original contents creation apparatus  10  in accordance with the first embodiment, the operation rule (first operation rule) that defines the operation of the case where the secondary contents violate the limitation rule can be contained in the original contents. In such a way, it is made possible to perform the appropriate operations in the derived contents creation apparatus  20  and the derived contents replay apparatus  30  when the secondary contents violate the limitation rule. 
     Moreover, according to the derived contents creation apparatus  20  in accordance with the first embodiment, the operation rule (third operation rule) that defines the operation in response to the detection result of the deletion of the secondary contents can be contained in the derived contents. In such a way, it is made possible to perform the appropriate operation when the derived contents replay apparatus  30  have detected the unauthorized deletion of the secondary contents. 
     Furthermore, according to the derived contents distribution system in accordance with the first embodiment, the first to fourth operation rules can be contained in the signature of the original contents. In such a way, it is made possible to protect the operation rules from the tamper. In addition, when the secondary contents violate the limitation, or when the secondary contents are deleted, the notice on the operation to be performed can be surely issued to the derived contents creation apparatus  20  or the derived contents replay apparatus  30 . 
     Second Embodiment 
     In the second embodiment, description will be made of a derived contents distribution system, in which the original contents creation apparatus is capable of setting a secondary contents insertion place as a placeholder in advance, and the derived contents creation apparatus can request beforehand the placeholder into which the secondary contents are to be inserted. 
     (Derived Contents Distribution System) 
     As shown in  FIG. 15 , the derived contents distribution system according to the second embodiment includes an original contents creation apparatus  110 , a derived contents creation apparatus  120 , and a derived contents replay apparatus  130 . In this derived contents distribution system, in comparison with that in  FIG. 1 , added is a placeholder request for designating the insertion place of the secondary contents in the original contents, the placeholder request being transmitted from the derived contents creation apparatus  120  to the original contents creation apparatus  110 . 
     Next, description will be made of detailed configurations and operations of the original contents creation apparatus  110 , the derived contents creation apparatus  120  and the derived contents replay apparatus  130 . 
     (Original Contents Creation Apparatus and Method) 
     As shown in  FIG. 16 , the original contents creation apparatus  110  includes an original contents acquisition unit  111 , a secondary content limitation rule acquisition unit  112 , a joining/signature unit  113 , a placeholder request receiving unit  114 , and a placeholder presentation unit  115 , and is connected to the original contents storage unit  60  and the secondary contents limitation rule storage unit  70 . 
     The placeholder request receiving unit  114  (receiving means) receives a placeholder request message from the derived contents creation apparatus  120 . Then, the placeholder request receiving unit  114  extracts identification information of the placeholder and a parameter (hereinafter, referred to as a “derived contents correctness verification parameter”) necessary to verify the correctness of the derived contents from the message. In the derived contents correctness verification parameter, a verification key of the electronic signature and identification information of a verification algorithm (hash algorithm, normalization algorithm, public-key algorithm or the like) are contained. Moreover, the placeholder request receiving unit  114  inputs the identification information of the placeholder to the original contents acquisition unit  111 . 
     The original contents acquisition unit  111  acquires original contents  1111  (refer to  FIG. 18 ) containing the placeholder concerned from the original contents storage unit  60 . 
     The secondary contents limitation rule acquisition unit  112  acquires a limitation rule  1121  (refer to  FIG. 19 ) from the secondary contents limitation rule storage unit  70 . Moreover, the secondary contents limitation rule acquisition unit  112  acquires a first operation rule that defines an operation of the case where the secondary contents violate the limitation rule. Furthermore, the secondary contents limitation rule acquisition unit  112  acquires a second operation rule that defines an operation of the case of not having detected the insertion of the secondary contents violating the limitation rule. 
     The joining/signature unit  113  joins the original contents  1111  and the secondary contents limitation rule  1121  to each other, associates the placeholder identification information and the derived contents correctness verification parameter with each other to give the associated information and parameter to signature data, and then gives an electronic signature to the original contents  1111 . Then, the joining/signature unit  113  outputs original contents  1131  added with the electronic signature (refer to  FIG. 20 ). Note that  FIG. 20  illustrates original contents which do not contain the second operation rule but only contain the first operation rule. 
     The placeholder presentation unit  115  presents a list of the placeholders contained in the original contents stored in the original contents storage unit  60  to the derived contents creation apparatus  120 . Therefore, it is made possible for the derived contents creation apparatus  120  to select the placeholder from plural candidates. 
     Next, an original contents creation method will be described by using  FIG. 17 . 
     (A) First, in Step S 401 , the place holder request receiving unit  114  receives the placeholder request message from the derived contents creation apparatus  120 . Then, in Step S 402 , the placeholder request receiving unit  114  extracts the identification information of the placeholder and the derived contents correctness verification parameter from the message. Moreover, the placeholder request receiving unit  114  inputs the identification information of the placeholder to the original contents acquisition unit  111 . 
     (B) Next, in Step S 403 , the original contents acquisition unit  111  acquires the original contents containing the placeholder concerned from the original contents storage unit  60 . Meanwhile, in Step S 404 , the secondary contents limitation rule acquisition unit  112  acquires the secondary contents limitation rule from the secondary contents limitation rule storage unit  70 . Moreover, the secondary contents limitation rule acquisition unit  112  acquires the first operation rule that defines the operation of the case where the secondary contents violate the limitation rule. 
     (C) Next, in Step S 405 , the joining/signature unit  113  joins the original contents and the secondary contents limitation rule to each other. Specifically, as shown in  FIG. 20 , the joining/signature unit  113  continuously joins a smil element of the original contents  1111  and a Policy element of the limitation rule  121 , and joins the first operation rule (Response element) thereto. 
     (D) Next, in Step S 406 , the joining/signature unit  113  gives the signature to the original contents thus joined. For example, as shown in  FIG. 20 , the joining/signature unit  113  gives hash values of the limitation rule, the first operation rule and the metadata (original contents) to the original contents, associates the placeholder identification information and the derived contents correctness verification parameter with each other to give the associated information and parameter to the signature data, and then gives a signature value and verification key information of the original contents creation apparatus. 
     (E) Then, in Step S 407 , the joining/signature unit  113  outputs the original contents added with the electronic signature. The outputted original contents added with the electronic signature are transmitted to the derived contents creation apparatus  120 . 
     (Derived Contents Creation Apparatus and Method) 
     As shown in  FIG. 21 , the derived contents creation apparatus  120  includes an original contents acquisition unit  121 , a secondary contents acquisition unit  122 , a limitation rule extraction unit  123 , a limitation rule evaluation unit  124 , a secondary contents insertion unit  125 , a derived contents signature unit  126 , a placeholder request unit  127 , a placeholder list acquisition unit  128 , and a parameter storage unit  129 , and is connected to the secondary contents storage unit  80 . 
     The parameter storage unit  129  stores the derived contents correctness verification parameter. 
     The placeholder request unit  127  (transmission means) acquires the derived contents correctness verification parameter from the parameter storage unit  129 , contains the parameter concerned in the placeholder request together with identification information of the requested placeholder, and transmits the placeholder request to the original contents creation apparatus  110 . Moreover, the placeholder request unit  127  associates the above-described parameter with the above-described placeholder identification information, and stores the parameter concerned in the parameter storage unit  129 . Note that, in the derived contents correctness verification parameter, a third operation rule by which the derived contents replay apparatus  130  is to abide when the unauthorized deletion of the secondary contents has been detected may be contained. 
     When the original contents creation apparatus  110  publicly opens the list of the placeholders, the placeholder list acquisition unit  128  acquires the placeholder list from the original contents creation apparatus  110 . For example, there is a method of acquiring the placeholder list from the original contents creation apparatus  110  by using HTTP. 
     The original contents acquisition unit  121  acquires the original contents  1131  (refer to  FIG. 20 ) added with the electronic signature, which contain the placeholder, from the original contents creation apparatus  10  through the network  40   a  or the storage medium  50   a.    
     The secondary contents acquisition unit  122  acquires secondary contents  1221  (refer to  FIG. 23 ) inserted into the original contents  1131  added with the electronic signature from the secondary contents storage unit  80 , and inputs the secondary contents  1221  to the limitation rule evaluation unit  124 . 
     The limitation rule extraction unit  123  extracts the secondary contents limitation rule  1121  from the original contents  1131  added with the electronic signature, and inputs the extracted secondary contents limitation rule  1121  to the limitation rule evaluation unit  124 . Moreover, the limitation rule extraction unit  123  extracts the first operation rule from the original contents  1131  added with the electronic signature, and inputs the extracted first operation rule to the limitation rule evaluation unit  124 . 
     The limitation rule evaluation unit  124  extracts the feature quantity of the secondary contents  1221  therefrom, and determines whether or not the secondary contents  1221  fit to the secondary contents limitation rule  1121 . When the secondary contents do not fit to the limitation rule, for example, the limitation rule evaluation unit  124  outputs a repudiation notice to the secondary contents insertion unit  125  according to the first operation rule, and makes the secondary contents insertion unit  125  stop the processing for inserting the secondary contents  1221  into the original contents  1131  added with the electronic signature. Meanwhile, when the secondary contents fit to the limitation rule, for example, the limitation rule evaluation unit  124  issues a notice on permission to insert the secondary contents  1221  into the original contents  1131  added with the electronic signature to the secondary contents insertion unit  125  according to the second operation rule. 
     Upon receiving the notice on the insertion permission, the secondary contents insertion unit  125  inserts the secondary contents  1221  into the designated placeholder, and outputs derived contents  1251  (refer to  FIG. 24 ). 
     The derived contents signature unit  126  acquires a correctness verification parameter of the derived contents corresponding to the identification information of the placeholder from the parameter storage unit  129 , and gives an electronic signature to the derived contents  1251  by signature means corresponding to the parameter concerned. For example, when a signature verification key, a hash algorithm, a normalized algorithm and a signature algorithm are contained in the parameter, the derived contents signature unit  126  gives the electronic signature by means of a signature key and an algorithm which correspond thereto. Then, the derived contents signature unit  126  outputs derived contents  1261  (refer to  FIG. 25 ) added with the electronic signature. 
     Next, a derived contents creation method will be described by using  FIG. 22 . 
     (A) First, in Step S 501 , the placeholder request unit  127  acquires the derived contents correctness verification parameter from the parameter storage unit  129 . Then, in Step S 502 , the placeholder request unit  127  contains the identification information of the placeholder in the placeholder request, and transmits the placeholder request containing the identification information to the original contents creation apparatus  110 . 
     (B) Moreover, in Step S 503 , the placeholder request unit  127  associates the above-described parameter with the above-described placeholder identification information, and stores the associated parameter and identification information in the parameter storage unit  129 . 
     (C) Next, in Step S 504 , the original contents acquisition unit  121  acquires the original contents  1131  (refer to  FIG. 20 ) added with the electronic signature, which contains the placeholder, from the original contents creation apparatus  110  through the network  40   a  or the storage medium  50   a . Then, in Step S 505 , the limitation rule extraction unit  123  extracts the secondary contents limitation rule  1121  and the first operation rule from the original contents  1131  added with the electronic signature, and inputs the extracted secondary contents limitation rule  1121  and first operation rule to the limitation rule evaluation unit  124 . 
     (D) Meanwhile, in Step S 505 , the secondary contents acquisition unit  122  acquires the secondary contents  1221  (refer to  FIG. 23 ) from the secondary contents storage unit  80 . 
     (E) Next, in Step S 507 , the limitation rule evaluation unit  124  extracts the feature quantity of the secondary contents from the acquired secondary contents  1221 , and determines whether or not the secondary contents fit to the secondary contents limitation rule  1121 . When the secondary contents do not fit to the limitation rule, the processing proceeds to Step S 508 , where, for example, the limitation rule evaluation unit  124  outputs the repudiation notice to the secondary contents insertion unit  125  according to the first operation rule, and makes the secondary contents insertion unit  125  stop the processing for inserting the secondary contents  1221  into the original contents  1131  added with the electronic signature. Meanwhile, when the secondary contents fit to the limitation rule, the processing proceeds to Step S 509 , where, for example, the limitation rule evaluation unit  124  issues the notice on permission to insert the secondary contents  1221  into the original contents  1131  added with the electronic signature to the secondary contents insertion unit  125  according to the second operation rule. 
     (F) In Step S 509 , the secondary contents insertion unit  125  inserts the secondary contents  1221  into the designated placeholder, and outputs the derived contents  1251 . 
     (G) Next, in Step S 510 , the derived contents signature unit  126  acquires the correctness verification parameter of the derived contents corresponding to the identification information of the placeholder concerned from the parameter storage unit  129 . Then, in Step S 511 , the derived contents signature unit  126  gives the electronic signature to the derived contents  1251  by the signature means corresponding to the parameter concerned. For example, as shown in  FIG. 25 , the derived contents signature unit  126  gives the hash value of the original contents to the derived contents, and gives the signature value and the verification key information of the derived contents creation apparatus. 
     (H) Then, the derived contents signature unit  126  outputs the derived contents  1261  added with the electronic signature. The outputted derived contents  1261  added with the electronic signature are transmitted to the derived contents replay apparatus  130 . 
     (Derived Contents Replay Apparatus and Method) 
     As shown in  FIG. 26 , the derived contents replay apparatus  130  includes a derived contents acquisition unit  131 , an original contents signature verification unit  132 , a derived contents signature verification unit  133 , a limitation rule evaluation unit  134 , and a derived contents replay processing unit  135 . 
     The derived contents acquisition unit  131  acquires the derived contents  1261  added with the electronic signature from the derived contents creation apparatus  120  through the network  40   b  or the storage medium  50   b.    
     The original contents signature verification unit  132  removes the secondary contents from the derived contents  1261  added with the electronic signature, verifies the electronic signature given by the original contents creation apparatus  110 , and issues a notice on a result of the verification to the derived contents replay processing unit  135 . 
     The derived contents signature verification unit  133  extracts the derived contents correctness verification parameter from the derived contents  1261  added with the electronic signature, verifies the electronic signature given by the derived contents creation apparatus  120  based on the parameter concerned, and issues a notice on a result of the verification to the derived contents replay processing unit  135 . 
     The limitation rule evaluation unit  134  determines whether or not the secondary contents  1221  contained in the derived contents  1261  meet the secondary contents limitation rule  1121 , and issues a notice on a result of the determination to the derived contents replay processing unit  135 . 
     The derived contents replay processing unit  135  performs the derived contents replay processing based on the results of the respective signature verifications and the result of the limitation rule evaluation. 
     Specifically, when at least any one of the results of the signature verifications is a failure, the derived contents replay processing unit  135  stops the replay processing immediately, and outputs an appropriate error message. Moreover, when the secondary contents do not fit to the limitation rule, for example, the derived contents replay processing unit  135  stops the replay processing immediately according to the first operation rule contained in the derived contents  1261 , and outputs an appropriate error message. 
     Meanwhile, when both results of the signature verifications are successes, and the secondary contents fit to the limitation rule, for example, the derived contents replay processing unit  135  performs the replay processing of the derived contents according to the second operation rule. 
     Note that, in the case of having received the derived contents  262  as shown in  FIG. 12 , which contain the third operation rule and the fourth operation rule, the derived contents replay apparatus  130  performs the processing according to the third operation rule in the case of having detected the deletion of the secondary contents and according to the fourth operation rule in the case of not having detected the deletion of the secondary contents. 
     Moreover, in the second embodiment, since the derived contents  1261  are metadata, the derived contents replay processing unit  135  performs acquisition/replay processing of the media data according to the description in the metadata. 
     Next, a derived contents replay method will be described by using  FIG. 27 . 
     (A) First, in Step S 601 , the derived contents acquisition unit  131  acquires the derived contents  1261  (refer to  FIG. 25 ) added with the electronic signature from the derived contents creation apparatus  120  through the network  40   b  or the storage medium  50   b.    
     (B) Next, in Step S 602 , the original contents signature verification unit  132  verifies the electronic signature given by the original contents creation apparatus  110 , and issues a notice on a result of the verification to the derived contents replay processing unit  135 . In Step S 603 , the derived contents replay processing unit  135  determines whether or not the result of the signature verification is a success. When the result is the success, the processing proceeds to Step S 605 , and when the result is a failure, the processing proceeds to Step S 604 , where the replay processing is stopped immediately, and an appropriate error message is outputted. 
     (C) Next, in Step S 605 , the derived contents signature verification unit  133  extracts the derived contents correctness verification parameter from the derived contents  1261  added with the electronic signature. Then, in Step S 606 , the derived contents signature verification unit  133  verifies the electronic signature given by the derived contents creation apparatus  120  based on the parameter concerned, and issues a notice on a result of the verification to the derived contents replay processing unit  135 . In Step S 607 , the derived contents replay processing unit  135  determines whether or not the result of signature verification is a success. When the result is the success, the processing proceeds to Step S 608 , and when the result is a failure, the processing proceeds to Step S 604 , where the replay processing is stopped immediately, and an appropriate error message is outputted. 
     (D) Next, in Step S 608 , the derived contents replay processing unit  135  determines whether or not the secondary contents fit to the limitation rule. When the secondary contents do not fit to the limitation rule, the processing proceeds to Step S 604 , where, for example, the replay processing is stopped immediately according to the first operation rule contained in the derived contents  1261 , and an appropriate error message is outputted. Meanwhile, when the secondary contents fit to the limitation rule, the processing proceeds to Step S 609 , where, for example, the derived contents replay processing unit  135  performs the replay processing of the derived contents according to the second operation rule. 
     Moreover, the derived contents replay processing unit  135  may determine whether or not the deletion of the secondary contents has been detected, and may perform the processing according to the third operation rule contained in the derived contents  262  (refer to  FIG. 12 ) when the deletion of the secondary contents has been detected, and according to the fourth operation rule contained in the derived contents  262  when the deletion of the secondary contents has not been detected. 
     Note that, in the flowchart of  FIG. 27 , the verification of the electronic signature given by the original contents creation apparatus (Step S 602 ), the verification of the electronic signature given by the derived contents creation apparatus (Step S 606 ), and the verification with respect to the limitation rule (S 607 ), are performed in this order; however, the order is not limited to this, and these verifications may be performed in an arbitrary order. Moreover, the original contents signature verification unit  132  and the derived contents signature verification unit  133  may stop the other processing immediately in the case of failing in the correctness verification of the signature. 
     (Function and Effect) 
     In the derived contents distribution system according to the second embodiment, the original contents creation apparatus  110  can explicitly designate the place into which the secondary contents are to be inserted. Therefore, it becomes easy for the original contents provider to control the insertion place of the secondary contents. 
     Moreover, the derived contents creation apparatus  120  can specify the insertion place of the secondary contents. 
     Furthermore, in the case of requesting the placeholder, the derived contents correctness verification parameter is notified to the original contents creation apparatus  110 , and contained in the signature of the original contents, thus making it possible only for the derived contents creation apparatus  120  that has acquired the placeholder to insert the secondary contents. 
     Moreover, in the derived contents distribution system according to the second embodiment, the parameter necessary for the correctness verification of the derived contents can be received by the derived contents creation apparatus  120 . Therefore, the parameter concerned can be prevented from being tampered after the derived contents are created. 
     Other Embodiments 
     Although the present invention has been described by the embodiments described above, it should not be understood that the descriptions and the drawings, which form a part of this disclosure, limit the invention. From this disclosure, various alternative embodiments, examples and operation technologies will be apparent to those skilled in the art. 
     For example, though the original contents creation apparatus, the derived contents creation apparatus and the derived contents replay apparatus have been described as apparatuses different from one another in the first and second embodiments, these apparatuses may be integrated into one apparatus. 
     Moreover, the original contents creation apparatus, the derived contents creation apparatus and the derived contents replay apparatus may include program holding units for holding control programs for allowing CPUs to execute the original contents creation processing, the derived contents creation processing and the derived contents replay processing, respectively. Each of the program holding units is, for example, a recording medium such as a RAM, a ROM, a hard disk, a flexible disk, a compact disc, an IC chip and a cassette tape. According to such a recording medium, storage, carriage, sale and the like of the control program can be performed easily. 
     Note that the original contents storage unit  60 , the secondary contents limitation rule storage unit  70  and the secondary contents storage unit  80  and the like are recording media for storing information. The recording media include, for example, a RAM, a ROM, a hard disk, a flexible disk, a compact disc, an IC chip, a cassette tape and the like. According to such recording media, the storage, carriage, sale and the like of the information can be performed easily. 
     As described above, it is a matter of course that the present invention incorporates the various embodiments and the like, which are not described here. Hence, the technical scope of the present invention is defined only by items specifying the invention, which are according to the scope of claims reasonable based on the above description.