Patent Publication Number: US-7908478-B2

Title: Data processing method and data reading method

Description:
The present invention incorporates the contents of International Application No. PCT/JP2004/003504 filed on Mar. 16, 2004 and PCT/JP2004/013331 filed on Sep. 13, 2004, by reference under CFR 1.57 (b). 
     FIELD OF THE INVENTION 
     The present invention relates to a data processing method capable of preventing illegal use of data (digital contents) distributed/delivered to a user through a recording medium such as a CD and a DVD, an internet line, a telephone line or the like, to a data reading method for reading the data processed by this processing method, and to a recording medium in which programs implementing these methods are stored. 
     BACKGROUND ART 
     The following system has been proposed as this type of conventional example. The system comprises a recording medium for distribution such as CD-ROM on which encrypted digital contents are recorded, management means for managing charges in accordance with the use of the digital contents by a user, a digital contents reproducing device which is used when the digital contents are reproduced by the user who has acquired the recording medium for distribution, and which can be connected to the management means via an internet line. A basic configuration of the system is such that when an application for digital contents is inputted to the digital contents reproducing device by the user under the condition of authentication and billing, the digital contents reproducing device transmits the application to the management means via the internet line, and the management means, after confirming authentication and billing of the user relating to the relevant application, transmits a decryption key data to the digital contents reproducing device via the internet line, and the digital content reproducing device decrypts the digital contents on the recording medium for distribution by using the decryption key data to reproduce it (for example, refer to Patent Document 1 or the like). 
     Patent Document 1: Japanese Published Unexamined Application No. 2002-334172. 
     However, in the case of the above-mentioned conventional example, in the digital contents reproducing device, once the digital contents on the recording medium for distribution is decrypted, not only the reproduction but also copy can be performed easily, so that it has an essential drawback that secondary illegal use cannot be prevented. 
     However, while the secondary illegal use can be prevented if there is added a function of automatically deleting the digital contents after a predetermined period of time from a reproduction application has passed, there arises another drawback that the collection of charges in accordance with the secondary use cannot be expected any longer. 
     This problem is not specific to the case where digital contents are distributed to a user through a recording medium for distribution, but there is a similar problem in the case where the digital contents are delivered through an Internet line or the like. Namely, profits that a contents holder or the like should obtain under normal circumstances are illegally lost, and in this regard, the distribution of the digital contents is impeded from being promoted under the present situation. 
     The present invention is created under the above-described background, and a first object of the present invention is to prevent illegal use of data (digital contents) and a second object is to provide a method for processing the data in which the collection of charges in accordance with secondary use of the data can be surely performed, a data reading method for reading the data processed by this processing method, and a recording medium on which programs implementing these methods are recorded. 
     DISCLOSURE OF THE INVENTION 
     In order to solve the above-described problems, a data illegal use preventing method of the present invention is characterized in that, in a method for processing data in which the data is encrypted and decrypted on a basis of a decryption bit length, thereby being read, the data is encrypted, a part of this data with a bit length different from the decryption bit length is omitted, and the omitted part is closed so as to make the data continuous. 
     Said data can be compressed before encryption. It is preferable that after said omitted part of the data is closed so as to make the data continuous, dummy data of the same bit length as that of the omitted data is added at the end of the data. 
     the bit length of the omitted data is a bit length different from a devisor of the decryption bit length. 
     In the case where the data is omitted at a plurality of positions, the bit length of the omitted data×the number of omission positions is a bit length different from the divisors of the decryption bit length. 
     A method for reading data of the present invention is a method for reading data using a data reading device for reading the data processed by the processing data method according to claim  1  and recorded in advance on a recording medium or on an auxiliary storage section of the data reading device, and which is a system including electronic equipment having an auxiliary storage device for pre-recording the omitted data and location information indicating in which part of the data the omitted data is located and said data reading device connected to the electronic equipment via a communication line, characterized in that the data reading device send a request to the electronic equipment via the communication line for the omitted data relating to the data to read and its location information in accordance with operation inputs, and the electronic equipment transmits the omitted data and its location information simultaneously or sequentially in reply to the request, the data reading device receives the omitted data and its location information to record them on the auxiliary storage section, and thereafter, in order to sequentially transfer the data on the recording medium or on the auxiliary storage section to a main storage section and to sequentially decrypt the data on the main storage section on the decryption bit length basis and read it, the location information on the auxiliary storage section is transferred to the main storage section, with reference to the location information, the omitted part of said data is recognized, and the omitted data on the auxiliary storage section is transferred to the main storage section, while the data on the recording medium or on the auxiliary storage section is transferred to the main storage section and the omitted data is connected to the omitted part of the data on the main storage to decrypt the data on the decryption bit length basis. 
     In the case where said data is encrypted before compression, the data reading device send a request to the electronic equipment via the communication line for the omitted data relating to the data to read and its location information in accordance with operation inputs, and the electronic equipment transmits the omitted data and their location information simultaneously or sequentially in reply to the request; the data reading device receives the omitted data and its location information to record them on the auxiliary storage section; and thereafter, in order to sequentially transfer the data on the recording medium or on the auxiliary storage section to a main storage section, to sequentially decrypt the data on the main storage section on a decryption bit length basis, and to restore the data from a compressed state to an original state and read it, the location information on the auxiliary storage section is transferred to the main storage section, with reference to the location information, the omitted part of said data is recognized, and the omitted data on the auxiliary storage section is transferred to the main storage section, while the data on the recording medium or on the auxiliary storage section is transferred to the main storage section and the omitted data is connected to the omitted part of the data on the main storage to decrypt the data on the decryption bit length basis and restore the data from the compressed state to the original state. 
     Said electronic equipment can be management means for managing the use of the data by the transmission of the omitted data and the location information. 
     The data recorded on the recording medium or on the auxiliary storage section of the data reading device is recorded in advance on said auxiliary storage device of the electronic equipment or on another auxiliary storage device, and is transmitted from the electronic equipment in accordance with the request of the data reading device to the electronic equipment via the communication line, and is recorded on the auxiliary storage section of said data reading device. 
     In the case where said data is permitted to be read for a predetermined period, it is preferable that the data reading device obtains an elapsed period from a point of time when the omitted data is received, and when the relevant elapsed period reaches the predetermined period, the data reading device deletes at least the omitted data on the auxiliary storage section. 
     It is also possible that the data reading device obtains an elapsed period from a point of time when the data is received, separately from the omitted data, and when the relevant elapsed period reaches a predetermined period, the data reading device deletes the data on the auxiliary storage section. 
     EFFECT OF THE INVENTION 
     In the case of the method for processing data according to claim  1  of the present invention, the data is encrypted, part of the data with the bit length different from the decryption bit length thereof is omitted, and the omitted part is closed so as to make the data continuous, so that a data row of the data after the omitted part becomes different from a data row when it was encrypted (that is, data row before omission). Consequently, in reading the data by the data reading device, when the part of the data after the omitted part is sequentially transferred to the main storage section and the data on the main storage section is sequentially decrypted by the decryption bit length, the data row of the data is different from the data row when it was encrypted, so that the data row does not return to the original data row before the encryption but is converted into an unknown sequence of numbers or alphanumerics. As a result, the data after the omitted part cannot be read, thereby preventing the illegal use of the data. 
     In the case of the method for processing data according to claim  2  of the present invention, the data is encrypted before compression. Such data is transferred to the main storage section of the data reading device, is decrypted by the decryption bit length, and is restored from the compressed state to the original state. Since the part of the data after the omitted part is converted into an unknown sequence of numbers or alphanumerics when decrypted, if an attempt is made to restore this unknown sequence of numbers or alphanumerics from the compressed state to the original state, the restoring process of the data by the data reading device will stop. Therefore, there are advantages for preventing the illegal use of the data. 
     In the case of the method for processing data according to claim  3  of the present invention, after the omitted part of said data the omitted part is closed so as to make the data continuous, dummy data of the same bit length as that of the omitted data is added at the end of the data. Specifically, the data length remains the same before and after the omission. Thereby, a third person will not know whether or not said data is partially omitted. Therefore, there are advantages for preventing the illegal use of the data. 
     In the case of the method for processing data according to claim  4  of the present invention, the bit length of the omitted data is a bit length different from a devisor of the decryption bit length. If the bit length of the omitted data is a divisor of the decryption bit length, the data row of the data after the omitted part which is transferred to the main storage section of the data reading device becomes the same as the data row when it was encrypted (that is, the data row before omission), so that the data other than the omitted part can be read. This can be prevented by the above-mentioned method. 
     In the case of the method for processing data according to claim  5  of the present invention, a product of the bit length of the omitted data and the number of omissions is a bit length different from the divisor of the decryption bit length. Therefore, if the product of the bit length of the omitted data and the number of omissions is a divisor of the decryption bit length, the data row of the data after the omitted part which is transferred to the main storage section of the data reading device becomes the same as the data row when it was encrypted (that is, the data row before omission), so that the data other than the omitted part can be read. This can be prevented by the above-mentioned method. 
     In the case of the method for reading data according to claim  6  of the present invention, the data reading device requests the omitted data and its location information which are recorded on the auxiliary storage device of the electronic equipment and records them on the auxiliary storage section of the data reading device, and thereafter, in order that the data reading device reads the data on the recording medium or on the auxiliary storage section, with reference to said location information, the omitted part of the data is recognized, the omitted data on the auxiliary storage section and the data on the recording medium or on the auxiliary storage section are transferred to the main storage section, the omitted data is connected to the omitted part of the data, and the data on the main storage section is decrypted by the decryption bit length and is read. Thus, by connecting the omitted data to the omitted part of the data, the data row in the vicinity of the omitted part is returned to the data row when it was encrypted. Therefore, when the data in the vicinity of the omitted part is decrypted, since it is not converted into an unknown sequence of numbers or alphanumerics, the data can be read. Namely, unless a user obtains the omitted data which is omitted as an authentic user, he cannot read the data, so that the illegal use of the data can be prevented. In addition, even if data recorded on the recording medium is simply copied, the user is required to obtain the omitted data as an authentic user to read the relevant data. Therefore, the collection of charges in accordance with secondary and tertiary use can be ensured. 
     In the case of the method for reading data according to claim  7  of the present invention, the data reading device requests the omitted data and its location information which are recorded on the auxiliary storage device of the electronic equipment and records them on the auxiliary storage section of the data reading device, and thereafter, in order that the data reading device reads the data on the recording medium or on the auxiliary storage section, with reference to said location information, the omitted part of the data is recognized, the omitted data on the auxiliary storage section and the data on the recording medium or on the auxiliary storage section are transferred to the main storage section, the omitted data is connected to the omitted part of the relevant data, the data on the main storage section is decrypted by the decryption bit length, and the relevant data is restored from the compressed state to the original state and is read. Thus, by connecting the omitted data to the omitted part of the data, the data row in the vicinity of the omitted part is returned to the data row when it was encrypted. Therefore, when the data in the vicinity of the omitted part is decrypted, since it is not converted into an unknown sequence of numbers or alphanumerics, the restoring process does not stop and the data can be read. Namely, unless a user obtains the omitted data which is omitted as an authentic user, he cannot read the data, so that the illegal use of the data can be prevented. In addition, even if data recorded on the recording medium is simply copied, the user is required to obtain the omitted data as an authentic user to read the relevant data. Therefore, the collection of charges in accordance with secondary and tertiary use can be ensured. 
     In the case of the method for reading data according to claim  8  of the present invention, said electronic equipment is management means for managing the use of the data by the transmission of the omitted data and the location information. Therefore, the invention enables billing or other processes in accordance with the use of the data. 
     In the case of the method for reading data according to claim  9  of the present invention, the data recorded on the recording medium or on the auxiliary storage section of the data reading device is recorded in advance on said auxiliary storage device of the electronic equipment or on another auxiliary storage device, and is transmitted from the electronic equipment in accordance with the request of the data reading device to the electronic equipment via the communication line, and is recorded on the recording medium or on the auxiliary storage section of said data reading device. Therefore, the data is easily made available. 
     In the case of the method for reading data according to claim  10  of the present invention, the data reading device obtains an elapsed period from a point of time when the omitted data is received, and when the elapsed period reaches a predetermined period, the data reading device deletes the transmitted omitted data. Consequently, the illegal secondary use of the data can be prevented. 
     In the case of the method for reading data according to claim  11  of the present invention, the data reading device obtains an elapsed period from a point of time when the data is received, separately from the omitted data, and when the relevant elapsed period reaches a predetermined period, the data reading device deletes the transmitted data, so that the data does not remain in the data reading device for a longer period than the predetermined period. Therefore, there are advantages for preventing the copy of the data for an illegal purpose. 
     The recording medium according to claim  12  of the present invention enables similar effects to those of claims  1  to  5 . The recording medium according to claim  13  of the present invention enables similar effects to those of claims  6  to  11 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram for explaining a first embodiment of the present invention, which is a configuration diagram of a digital contents illegal use preventing system, including a configuration diagram of a device for creating a recording medium for distribution used in this system. 
         FIG. 2  is a flowchart of reproduction software used for this system. 
         FIG. 3  is a flowchart of an interruption program for user registration which is processed by a control section in a management center of this system. 
         FIG. 4  is a flowchart of an interruption program for piece data delivery which is processed by the control section in the management center of this system. 
         FIG. 5  is a flowchart of a recording medium creating software executed by a computer which is the device for creating a recording medium for distribution used for this system. 
         FIG. 6  is a configuration diagram of a digital contents illegal use preventing system according to a second embodiment of the present invention. 
         FIG. 7  is a flowchart of reproduction software used for this system. 
         FIG. 8  is a flowchart of an interruption program for user registration which is processed by a control section in a delivery management center of this system. 
         FIG. 9  shows an interruption program for piece data delivery which is processed by the control section in the delivery management center of this system. 
         FIG. 10  is a configuration diagram of a digital contents illegal use preventing system according to a third embodiment of the present invention. 
         FIG. 11  is a flowchart of reproduction software used for the digital contents illegal use preventing system. 
         FIG. 12  is a flowchart of an interruption program for contents download. 
         FIG. 13  is a configuration diagram of a digital contents illegal use preventing system according to a fourth embodiment of the present invention. 
         FIG. 14  is a flowchart of reproduction software used for this system. 
         FIG. 15  is diagrams showing a contents file of this system,  FIG. 15A  being an image diagram of a data body and  FIG. 15B  being an image diagram of a part α of the data body. 
         FIG. 16  is a flowchart of recording medium creating software executed by a computer which is a device for creating a recording medium for distribution used in this system. 
         FIG. 17  is a configuration diagram of a digital contents illegal use preventing system according to a fifth embodiment of the present invention. 
         FIG. 18  is a flowchart of reproduction software used for this system. 
     
    
    
     DESCRIPTION OF REFERENCE NUMERALS 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 α 
                 recording medium for distribution 
               
               
                   
                 100 
                 digital contents illegal use preventing system 
               
               
                   
                 101 
                 management center 
               
               
                   
                 120 
                 digital contents reproducing device 
               
               
                   
                 140 
                 device for creating a recording medium for 
               
               
                   
                   
                 distribution 
               
               
                   
                 200, 300 
                 digital contents illegal use preventing 
               
               
                   
                   
                 system 
               
               
                   
                 210, 310 
                 delivery management center 
               
               
                   
                 220, 320 
                 digital contents reproducing device 
               
               
                   
                 400 
                 digital contents illegal use preventing system 
               
               
                   
                 410 
                 management center 
               
               
                   
                 420 
                 digital contents reproducing device 
               
               
                   
                 500 
                 digital contents illegal use preventing system 
               
               
                   
                 510 
                 delivery management center 
               
               
                   
                 520 
                 digital contents reproducing device 
               
               
                   
                   
               
            
           
         
       
     
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, the embodiments of the present invention are described. 
     Embodiment 1 
     A first embodiment of the present invention is first described with reference to  FIGS. 1 and 2 .  FIG. 1  is a configuration diagram of a digital contents illegal use preventing system as shown in  FIG. 1 , including a configuration diagram of a device for creating a recording medium for distribution used for this system,  FIG. 2  is a flowchart of reproduction software used for this system,  FIG. 3  is a flowchart of an interruption program for user registration which is processed by a control section in a management center of this system, and  FIG. 4  is a flowchart of an interruption program for piece data delivery which is processed by the control section in this management center. 
     A digital contents illegal use preventing system  100  as shown in  FIG. 1  is a system preventing a contents file on a recording medium for distribution α which has been distributed to a user for a rental purpose from being used illegally. The object of rental is the contents file, not the recording medium for distribution α itself. 
     This system has a basic structure comprising the recording medium for distribution α on which a contents file having header information a and a data body b is recorded with part of the data body b (omitted data) omitted, a management center  110  (electronic equipment) which is management means for managing the utilization of the contents file on the recording medium for distribution α, in which piece data d consisting of the omitted data and location information indicating in which part of the data body b the relevant omitted data is located is prepared in advance, and which can deliver the relevant piece data d via a communication line β, and a digital contents reproducing device  120  (data reading device) which is a device used when the contents file on the recording medium for distribution α is reproduced and copied, having a function of intercommunicating with the management center  110  via the communication line β. 
     The communication line β is a wired or wireless internet line such as a digital line including an optical communication line or analog line including a telephone line, or a line transmitting/receiving an electric wave signal such as digital broadcasting or satellite broadcasting, and this is used to perform intercommunication between the management center  110  and the digital contents reproducing device  120 . 
     The recording medium for distribution α is a general recording medium such as CD and DVD. The contents file on the recording medium for distribution α has the data body b (data) which is data of music, moving image, static image, text, game, software or the like, and the header information a containing reproduction information for reproducing this data body b, and contents information such as a contents ID assigned to this data body b and a WEB address information of the management center  110 , and after the header information a and the data body b are encrypted, respectively, the contents file obtains a data structure in which part of the relevant data body b is omitted. At the beginning of the data body b, starting location information indicating a starting location of the relevant data body b is recorded. The location information indicating in which part of the data body b the omitted data is located is a data length or a time from the starting location information to the omitted part. Reproduction information is an address value to be read first or the like. 
     The management center  110  is a server operated by a person doing a business in which the data body b on the recording medium for distribution α is rented to a user and a rental fee is collected from the user under an agreement between the user and an owner of copyright or the like of a copyrighted work contained in the data body b. In the figure, reference numeral  111  denotes a piece data DB (an auxiliary memory device) on which the piece data d and a decryption key c 2  necessary for decrypting the data body b of the contents file are recorded in advance, reference numeral  112  denotes a control section such as a computer, reference numeral  113  denotes a communication section for performing communication, reference numeral  114  denotes a user information DB on which user information is recorded and information such as authentication and accounting based on the user information is recorded sequentially, reference numeral  115  denotes a software DB on which the reproduction software and a decryption key c 1  necessary for decrypting the header information a of the contents file are recorded in advance, and reference numeral  116  denotes a memory section such as a hard disk. 
     On the memory section  116 , in addition to basic programs such as an operation system as a server, an interruption program for user registration as shown in  FIG. 3 , an interruption program for reproduction software download not shown in the figure, an interruption program for piece data delivery as shown in  FIG. 4  and the like are recorded. The contents of these programs will be described later. By processing these programs in the control section  112 , this server exerts a function as the management center  110 . Furthermore, on the memory section  116 , data necessary for user registration processing and data necessary for reproduction application processing are recorded. 
     The contents ID indicating the corresponding contents file is added to the piece data d on the piece data DB  111 . Thus, by using the contents ID, a correspondence relationship between the contents file on the recording medium for distribution α and the piece data d on the piece data DB  111  coincides. Similarly, a user ID and a player ID of a corresponding user are added to the user information on the user information DB  114 . Thus, by using the user ID or the player ID, a correspondence relationship between the user and the user information in the user information DB  114  coincides. 
     Since this management center  110  confirms (namely, authenticates) the user ID and a password and in addition, confirms whether or not the player ID coincides before transmitting the piece data d to the digital contents reproducing device  120 , the player ID is also useful for preventing illegal use. 
     The digital contents reproducing device  120  is a general-purpose computer used by the user. In the figure, reference numeral  121  denotes a control section such as CPU, reference numeral  122  denote an output section such as a monitor and a speaker, reference numeral  123  denotes an operation section such as a keyboard and a mouse, reference numeral  124  denotes a reproduction and copy section reading/writing the data with respect to the recording medium for distribution α and the like, and reference numeral  125  denotes a memory section (auxiliary storage section) such as a hard disk, and reference numeral  126  denotes a communication section for performing communication. 
     On the memory section  125 , in addition to basic programs such as an operation system as a computer, the reproduction software as shown in  FIG. 2  is recorded. This reproduction software is chargeable or free software downloaded through the communication line β from the management center  110  under the condition of user registration, and application software necessary for reproducing the contents file on the recording medium for distribution α. Furthermore, the player ID assigned to the reproduction software is transmitted from the management center  110  to the memory section  125  together with the relevant reproduction software to be stored. Further, on the memory section  125 , the piece data d, the decryption keys c 1 , c 2  and the like which have been transmitted from the management center  110  are recorded, and rental information indicating a rental period and the like are recorded. 
     The contents of the reproduction software will be described later. The processing of this software by the control section  121  allows this computer to exert the function as the digital contents reproducing device  120 . 
     The operation of the digital contents illegal use preventing system  100  configured as described above is described and in conjunction of this, the operation of the management center  110 , the operation of the digital contents reproducing device  120 , and the contents of the respective programs are described. 
     The user operates the operation section  123  of his or her own computer (computer equivalent to the digital contents reproducing device  120 , which is in a state that the reproduction software as shown in  FIG. 2  is not downloaded) to access the management center  110  via the communication line β and to request user registration. The management center  110  processes the interruption program for user registration as shown in  FIG. 3  in accordance with this request, and transmits the data necessary for the user registration to the computer (s 21 ). Thereafter, the user inputs his or her name, address and payment condition, “a bank account number or a credit card number of his or hers, etc.” as displayed in a user registration screen through the operation section  123  of the computer and transmits this registration data to the management center  110  via the communication line β. Then, the management center  110  creates a user ID and a password in accordance with this to register the relevant user ID and the like in the user information DB  114  together with the registration data as user information (s 22 ). On the other hand, the relevant user ID and the password are transmitted to the computer of the user via the communication line β (s 23 ). Then, the processing of the interruption program for user registration is finished. The user ID and the password may be inputted by the user himself or herself at the time of user registration. 
     Thereafter, the user operates his or her computer to access the management center  110  and inputs a request for the download of the reproduction software. At this time, the user ID and the password are required. Then, the computer of the user transmits the request to the management center  110  via the communication line β. The management center  110  processes the interruption program for reproduction software download in accordance with this request, reads out the reproduction software and the decryption key c 1  on the software DB  115 , and transmits them to the computer of the user via the communication line β. Then, the reproduction software as shown in  FIG. 2  is downloaded to the memory section  125  of the computer and installed. At the same time, the decryption key c 1  is recorded on the memory section  125 . This makes the computer into the digital contents reproducing device  120 . 
     When the recording medium for distribution α is set in the reproduction and copy section  124  by the user and the execution of the reproduction software is operated, this digital contents reproducing device  120  processes the relevant reproduction software, and outputs and displays data of a play list showing a reproducing player and rented contents contained in the relevant reproduction software on the output section  122 . Then, the play list is displayed on a screen of the relevant reproducing player (s 1 ). Namely, the contents file having a predetermined flag hoisted, which indicates that a reproduction application has been made, is displayed on the play list. Then, based on this play list, whether or not reproducing operation has been performed is determined through the operation section  123  (s 2 ). 
     If it is determined that the reproducing operation has not been performed, then it is determined whether or not reading operation (operation of DISC LOAD) of the recording medium for distribution α has been performed through the operation section  123  (s 3 ). If the operation of DISC LOAD is performed, then a contents list showing a contents file for which reproduction application has not been made is outputted and displayed on the output section  122  (s 4 ). Namely, while the decryption key c 1  on the memory section  125  is read out, the header information a of a contents file with the predetermined flag not hoisted among the contents files on the recording medium for distribution α is read out and decrypted by using the relevant decryption key c 1  to read out contents information contained in the relevant header information a and to display it on the contents list. 
     Thereafter, when an application for reproduction of the contents file on the contents list is performed by the user, the decryption key c 1  on the memory section  125  is read out and meanwhile, the header information a of the contents file on the recording medium for distribution α is read out and decrypted by using the relevant decryption key c 1  to read out the contents information contained in the relevant header information a. Then, based on a WEB address contained in the relevant contents information, the contents ID contained in the relevant contents information is transmitted to the management center  110  via the communication line β. In this manner, the execution of the reproduction application processing is transmitted. 
     The management center  110  processes the interruption program for piece data delivery as shown in  FIG. 4 . Then, it reads out the data necessary for the reproduction application processing from the memory section  116  and transmits it to the digital contents reproducing device  120  via the communication line β (s 31 ). Based on this data, the digital contents reproducing device  120  outputs and displays a reproduction application screen on the output section  122  (s 5 ). 
     Thereafter, when the user sequentially inputs or selects a rental period through the operation section  123  as displayed on the reproduction application screen (this determines a rental amount of money), and finally inputs the user ID and the password through the operation section  123  as a reproduction application of the recording medium for distribution α (s 6 ), the digital contents reproducing device  120  shifts the display output of the output section  122  to an authentication screen, while the inputted application data is transmitted to the management center  110  via the communication line β. At this time, the contents ID contained in the contents information of the header information a on the recording medium for distribution α and the player ID on the memory section  125  are read out and transmitted to the management center  110  together with the application data (s 7 ). 
     The management center  110  confirms the authentication of the user relating to the application (s 32 ). Namely, with reference to the transmitted user ID and player ID of the user etc., the user information of the relevant user is read out from the user information DB  114 , and whether or not the relevant user is an authentic user is confirmed. At this time, the management center  110  has in advance prepared a list of inappropriate persons with nonpayments of rental fee more than or equal to predetermined times or the like in the user information DB  114 , and in addition to the authentication, confirms whether or not the user falls under the list of inappropriate persons (this confirmation of the list of inappropriate persons is arbitrary). 
     In the case where the management center  110  has confirmed that the user relating to the application is an unauthentic user or an authentic user but a person who falls under the list of inappropriate persons, the rejection of the application of the user is transmitted to the digital contents reproducing device  120  via the communication line β (s 33 ). Then, the interruption program for piece data delivery is finished. 
     On the other hand, in the case where it has been confirmed that the user relating to the application is an authentic user and a person who does not fall under the list of inappropriate persons, with reference to the player ID of the user or the like, accounting is recorded on the user information of the user on the user information DB  114 , while with reference to the contents ID, the piece data DB  111  is searched to read out the decryption key c 2  and the piece data d corresponding to the relevant contents ID, and to transmit them to the digital contents reproducing device  120  as a reply indicating that the application of the user is accepted together with the rental information indicating the rental period and the like which are contained in the application data via the communication line β (s 34 ). Then, the processing of the interrupt program for piece data delivery is finished. 
     The charges are summed up based on the user information DB  114  for every predetermined period, and is charged to a bank/a credit card company  130  or charged directly to the user, so that the user transfers the charge to an account or pays it in a convenience store or the like. Furthermore, in the case where the management center  110  is connected to the bank/credit card company  130  via the communication line β, it is obviously possible to immediately settle accounts, too. 
     Thereafter, upon receiving the rejection of the application of the user via the communication line β (s 8 ), the digital contents reproducing device  120  outputs and displays an error message on the output section  122  (s 9 ). On the other hand, when the piece data d and the like are received via the communication line β (s 8 ), the predetermined flag is hoisted, while the decryption key c 2 , the piece data d and the rental information are recorded on the memory section  125  (s 10 ). At the same time, by using a clock function of the computer, a piece data transmission date and time is recorded on the memory section  125 . Then, the play list is updated, and outputted and displayed on the output section  122 , so that a file name of the contents file with the piece data d obtained is displayed on the relevant play list (s 1 ). 
     Thereafter, when the reproducing operation of the contents file is performed based on the play list through the operation section  123  (s 2 ), the digital contents reproducing device  120  reads out the decryption key c 1  on the memory section  125 , and meanwhile, it reads out the header information a relating to the relevant contents file on the recording medium for distribution α and decrypts the header information a by using the decryption key c 1 . Then, the data body b on the recording medium for distribution α is read out by using the reproduction information contained in the relevant header information a and is reproduced while being decrypted with the decryption key c 2  on the memory section  125  (s 11 ). In addition, while the starting location information of the data body b on the recording medium for distribution α is read out, the piece data d on the memory section  125  is read out and the counting of a data length or a time from the starting location information to the location information contained in the piece data d is started (s 12 ). Thereafter, whether or not the counting is finished is determined (s 13 ). Thereby, the omitted part of the data body b is recognized. As a result of this determination, when it is determined that the counting is finished and the omitted part of the data body b is recognized, the piece data d on the memory section  125  is read out and the omitted data contained in the relevant piece data d is read out as the data of the omitted part of the relevant data body b and is reproduced while being decrypted with the decryption key c 2  on the memory section  125  (s 14 ). Then, the data body b on the recording medium for distribution α is read out again and is subsequently reproduced while being decrypted with the decryption key c 2  on the memory section  125  (s 15 ). This reproduction software program is finished upon end processing by the user. 
     Furthermore, the reproduction software, in addition to the above-described basic function, has a piece data management function which is resident in the digital contents reproducing device  120  to manage the piece data d when the digital contents reproducing device  120  is turned ON. This piece data management function manages the piece data d on the memory section  125 , while it obtains a difference between a piece data transmission data and time and a current date and time as an elapsed period from a time point when the piece data d is transmitted, and when this reaches the rental period contained in the rental information, it is determined to be outside of the rental period, and the piece data d and the decryption key c 2  on the memory section  125  are deleted, while the predetermined flag is hauled down. 
     Thus, in this system  100 , even when the user operates to reproduce the recording medium for distribution α by using the digital contents reproducing device  120 , the data body b of the contents file on the recording medium for distribution α cannot be reproduced unless the user obtains the piece data d from the management center  110  as an authentic reproduction applicant. In this manner, the temporary, illegal use of the contents file on the recording medium for distribution α can be prevented. In addition, with respect to the contents file whose rental period has passed, the piece data d is deleted, which can prevent secondary illegal use. Furthermore, even if the recording medium for distribution α is copied to another recording medium for distribution by the user, since in the contents file recorded on the another recording medium for distribution, the reproduction information contained in the header information a is omitted, the contents file cannot be reproduced unless the user obtains the piece data d as an authentic reproduction user. Therefore, tertiary, illegal use can also be prevented. 
     Furthermore, outside of the rental period of the recording medium for distribution α, only the piece data d or the like on the memory section  125  is deleted automatically, and the contents file on the recording medium for distribution α remains as it is. Thus, the contents file can be created by copying the recording medium for distribution α to a new recording medium, using the digital contents reproducing device  120 . In order to reproduce such a contents file on the recording medium for distribution α, authentication to the management center  110  and payment of rental fee by using the digital contents reproducing device  120  are required, so that the collection of charges in accordance with the secondary and tertiary use can be ensured. 
     In addition, since the charge relating to the contents file data body b is designed to be collected in the reproduction application separately from the recording medium for distribution α, it is also possible that the recording medium for distribution α is distributed for free and thereafter, the billing is performed to an applicant for reproduction. Alternatively, it is also possible that the recording medium for distribution α is sold only at an amount of money relating to this and thereafter, the billing is performed with respect to an applicant for reproduction. Furthermore, in the case where the contents of the contents file recorded on the recording medium for distribution α are those of a specialized book such as a medical book, the contents of the specialized book such as the medical book are divided item by item and each item is recorded as one contents file on the recording medium for distribution α, which allows reproduction application for each item. This makes it possible to always have an even expensive specialized book ready at home and refer to it by applying for reproduction (on a rental basis) for each item as necessary. By using this system in this manner, various novel business forms can be addressed. 
     Furthermore, in the case where a plurality of contents files are recorded on the recording medium for distribution α, from the standpoint of the user, only the contents file which he or she wants to listen to or view can be rented. On the other hand, from the standpoint of a creator of the recording medium for distribution α, since the recording medium for distribution α can be made into the one on which arbitrary contents files are recorded without considering the taste of each user, fashion or the like, creation costs of the relevant recording medium for distribution α can be reduced. 
     Here, a description of a device for creating a recording medium for distribution  140  which is used to create the recording medium for distribution α is given with reference to  FIGS. 1 and 5 .  FIG. 5  is a flowchart of a recording medium creating software executed by a computer which is a device for creating a recording medium for distribution used for this system. 
     The device for creating a recording medium for distribution  140  is a device used by a proprietor of the management center  110  or a person concerned with the same, and has a configuration in which part of the relevant data body b is separated from a contents file having the header information a and the data body b, and the relevant omitted data and the location information thereof are recorded as the piece data d, while the contents file with the piece data d separated is recorded on the set recording medium to create the recording medium for distribution α. Here, a computer is used. 
     In  FIG. 1 , reference numeral  141  denotes an input section reading out digital contents from a master disk, reference numeral  142  denotes a control section such as CPU which processes the recording medium creating software shown in  FIG. 5 , reference numeral  143  denotes a recording section in which a recording medium such as CD and DVD can be set and which records a contents file on the recording medium, reference numeral  144  denotes a piece data memory recording the piece data d separated from the contents file, and reference numeral  145  denotes a memory section such as a hard disk on which the recording medium creating software is recorded. 
     Hereinafter, the contents of the recording medium creating software shown in  FIG. 5  are described, and in addition, the operation of the device for creating a recording medium for distribution  140  is described. 
     The device for creating a recording medium for distribution  140 , upon being turning On, processes the recording medium creating software on the memory section  145 . Then, the master disk is set manually or automatically in the input section  141 . Furthermore, a recording medium such as DVD is sequentially set in the recording section  143 . 
     The contents file is read out from the master disk set by the input section  141  (s 1 ), and the header information a and the data body b of the relevant contents file are encrypted, respectively (s 2 ). Thereafter, part of the data body b contained in the contents file is separated, and the relevant separated omitted data is recorded on the piece data memory  144  as the piece data d together with its location information (s 3 ). Meanwhile, the relevant contents file is recorded on the recording medium such as DVD which is set in the recording section  143  (s 4 ). This finishes the software. The piece data d recorded on the piece data memory  144  is transferred to the management center  110  via the communication line β. In such a manner, the recording medium for distribution α is created. The piece data d can be recorded on the piece data memory  144  can also be recorded on the recording medium and sent to the management center  110 . 
     The digital contents illegal use preventing system  100  as described above may be subject to any design modification as long as it comprises a recording medium for distribution on which a contents file having header information and a data body is recorded with part of the data body omitted, management means which is means for managing the utilization of the contents file on the recording medium for distribution, has a data base on which the omitted data and location information indicating in which part of the data body the omitted data is located are recorded and can transmit the relevant omitted data and its location information via a communication line, and a digital contents reproducing device which is used at least in reproducing the contents file on the recording medium for distribution and has a function capable of intercommunication with the management means via the communication line, wherein when an application for reproduction of the contents file is inputted to the digital contents reproducing device by a user, the digital contents reproducing device transmits the relevant application to the management means via the communication line, and the management means transmits the omitted data and its location information of the contents file relating to the relevant application simultaneously or subsequently to the relevant digital contents reproducing device via the communication line, and the digital contents reproducing device receives the relevant omitted data and the location information simultaneously or subsequently to record them on a memory section and reads out the data body of the contents file on the recording medium for distribution to reproduce it, and at the same time, recognizes the omitted part of the data body with reference to the location information read out from the memory section and reads out and reproduces the omitted data on the memory section as the data of the relevant omitted part. 
     Therefore, in the recording medium for distribution α, although the header information a and the data body b are encrypted, respectively, it is arbitrary whether or not the encryption is performed. However, it is desirable that at least the data body b is encrypted. Furthermore, while the contents file is structured to have the header information a and the data body b, it is obviously possible to record the contents file with other information added thereto. This other information includes a program by which it is determined whether or not the reproduction software has been installed in the computer of the user, and when it is determined that the reproduction software has not been installed, HP of the management center  110  is automatically accessed, and the like. When this program has been recorded and the user sets the recording medium for distribution α which he or she has in advance obtained in his or her computer (computer equivalent to the digital contents reproducing device  120 , which is in a state that the reproduction software is not downloaded), the WEB address of the management center  110  is read out, and based on this, the management center  110  is accessed. Thereafter, the reproduction software can be obtained by the above-described procedure. Although the contents file is designed such that a part thereof is omitted, it can be obviously designed such that a plurality of points are omitted. 
     While the location information is designed to be a data length or a time from the starting location information to the omitted part, it may be an address value indicating the omitted part or the like. In this case, it is sequentially determined whether or not an address value of the data body b on the recording medium for distribution α to be read out next and the location information coincide with each other, and as a result of the determination, when they are determined not to coincide with each other, the data body b on the recording medium for distribution α which the address value indicates is read out, while when they are determined to coincide with each other, the omitted data on the memory section  125  is read out. 
     While the piece data d consists of the omitted data body and the location information, whether or not the location information is contained is arbitrary. In this case, for example, omitted location information indicating the omitted part is in advance recorded before the omitted part of the data body b, and the data body b is reproduced, and further counting is performed from the starting location information to the omitted location information. When this counting is finished, the omitted data on the memory section  125  may be reproduced as the data of the relevant omitted part. Alternatively, a location of the omitted part of the data body b is predetermined, and the location information of the omitted data is prepared in the reproduction software. It is possible that the data body b is reproduced and that at the same time, the omitted part of the data body b is recognized based on this location information and that the omitted data on the memory section  125  is reproduced as the data of the relevant omitted part. 
     Thus, the contents of the reproduction software are only one example, and any modification in design can be made as long as similar contents can be realized. It is true of the interruption program for user registration, the interruption program for reproduction software download, and the interruption program for piece data delivery. 
     In the first embodiment, the system can also be changed in design so as to prevent illegal use of a contents file on the recording medium for distribution α not delivered on a rental basis but transferred to the user for pay or for free. In this case, advantages similar to the foregoing are also brought about. In the contents of the reproduction software used in this case, only the series of processings when the contents file is inside and outside of the rental period are deleted. With respect to the digital contents reproducing device, the reproduction software may not be downloaded from the management center  110 , but may be installed through a recording medium such as CD. Furthermore, obviously, the digital contents reproducing device is not a computer but can be a dedicated device, and any configuration can be used as long as the digital contents reproducing device has the function in which when a reproduction application for a contents file under the condition of authentication and billing is inputted by a user, the relevant application is transmitted to the management center  110  via the communication line β and thereafter when the piece data d is transmitted from the management center  110  via the communication line β, the data body b on the recording medium for distribution α is reproduced by using the header information on the recording medium for distribution α and the relevant piece data d at the time of reproducing operation. 
     Embodiment 2 
     Next, a second embodiment of the present invention is described with reference to the drawings.  FIG. 6  is a configuration diagram of a digital contents illegal use preventing system,  FIG. 7  is a flowchart of reproduction software used for this system,  FIG. 8  is a flowchart of an interruption program for user registration which is processed by a control section in a delivery management center of this system, and  FIG. 9  shows an interruption program for piece data delivery which is processed by the control section in the delivery management center of this system. 
     A digital contents (data) illegal use preventing system  200  as shown in  FIG. 7  is a system preventing a contents file delivered to a user for a rental purpose from being used illegally. 
     This system has a configuration comprising a delivery management center  210  (electronic equipment) which is a server in which a contents file having the header information a and the data body b is prepared in advance with the header information a and with part of the data body b omitted, and the piece data d consisting of omitted data and location information indicating in which part of the data body b the relevant omitted data is located is prepared in advance separately from the relevant contents file, the delivery management center  210  functioning as delivery management means for delivering the relevant contents file via a communication line β (as in Embodiment 1) and meanwhile, managing the utilization of the relevant data body b, and a digital contents reproducing device  220  (data reading device) which can intercommunicate with the delivery management center  210  via the communication line β and is used when the contents file delivered from the delivery management center  210  is reproduced and copied. 
     The contents file has the data body b which is data of music, moving image, static image, text, game, software or the like, and the header information a containing reproduction information for reproducing this data body b and contents information such as a contents ID assigned to this data body b and WEB address information of the delivery management center  210 , and after the header information a and the data body b are encrypted, respectively, the contents file obtains a data structure in which part of the relevant data body b is omitted. At the beginning of the data body b, starting location information indicating a starting location of the relevant data body b is recorded. The location information indicating in which part of the data body b the omitted data is located is a data length or a time from the starting location information to the omitted part. 
     The delivery management center  210  is a server operated by a person doing a business in which the content file is rented to a user and a rental fee is collected from the user under an agreement between the user and an owner of copyright or the like of a copyrighted work contained in the data body b of the contents file to be delivered. In the figure, reference numeral  211  denotes a digital contents DB (an auxiliary memory device) on which the contents file having the header information a and the data body b is in advance recorded with part of the data body b omitted, reference numeral  212  denotes a control section such as a computer, reference numeral  213  denotes a communication section for performing communication, reference numeral  214  denotes a user information DB on which user information is recorded and information such as authentication and billing based on the user information is recorded sequentially, reference numeral  215  denote a software DB on which the reproduction software and a decryption key c 1  necessary for decrypting the header information a of the contents file are recorded in advance, reference numeral  216  denotes a piece data DB on which the piece data d and the decryption key c 2  necessary for decrypting the data body b of the contents file are recorded in advance, and reference numeral  217  denotes a memory section such as a hard disk. 
     On the memory section  217 , in addition to basic programs such as an operation system as a server, an interruption program for user registration as shown in  FIG. 8 , an interruption program for reproduction software download not shown in the figure, an interruption program for contents download not shown in the figure, an interruption program for piece data delivery as shown in  FIG. 9  and the like are recorded. The contents of these programs will be described later. By processing these programs in the control section  212 , this server exerts a function as the delivery management center. Furthermore, on the memory section  217 , data necessary for user registration processing and data necessary for reproduction application processing are recorded. 
     The contents ID indicating the corresponding contents file is added to the piece data d on the piece data DB  216 . Thus, by using the contents ID, a correspondence relationship between the contents file and the piece data d on the piece data DB  216  coincides. Similarly, a user ID and a player ID of a corresponding user are added to the user information on the user information DB  214 . Thus, by using the user ID or the player ID, a correspondence relationship between the user and the user information in the user information DB  214  coincides. 
     Since the delivery management center  210  confirms (namely, authenticates) the user ID and a password and in addition, confirms whether or not the player ID coincides before transmitting the piece data d to the digital contents reproducing device  220 , the player ID is also useful for preventing illegal use. 
     The digital contents reproducing device  220  is a general-purpose computer used by the user. In the figure, reference numeral  221  denotes a control section such as CPU, reference numeral  222  denote an output section such as a monitor and a speaker, reference numeral  223  denotes an operation section such as a keyboard and a mouse, reference numeral  224  denotes a memory section such as a hard disk, reference numeral  225  denotes a reproduction and copy section reading/writing the data with respect to the recording medium or the like, and reference numeral  226  denotes a communication section for performing communication. 
     On the memory section  224 , in addition to basic programs such as operation system as a computer, the reproduction software as shown in  FIG. 7  is recorded. This reproduction software is chargeable or free software downloaded through the communication line β from the delivery management center  210  under the condition of user registration, and application software necessary for reproducing the contents file. Furthermore, the information of a WEB address of the delivery management center  210  in which the player ID assigned to the reproduction software and the piece data d are stored is transmitted from the delivery management center  210  to the memory section  224  together with the relevant reproduction software and is stored therein. Further, on the memory section  224 , the piece data d, the decryption keys c 1 , c 2  and the like which have been transmitted from the delivery management center  210  are recorded, and rental information indicating a rental period and the like is recorded. 
     The contents of the reproduction software will be described later. The processing of this reproduction software by the control section  221  as shown in  FIG. 7  allows this computer to exert the function as the digital contents reproducing device  220 . 
     The operation of the digital contents illegal use preventing system  200  configured as described above is described and in conjunction with this, the operation of the digital contents reproducing device  220 , the operation of the delivery management center  210 , and the contents of the respective programs are described. 
     The user operates the operation section  223  of his or her own computer (computer equivalent to the digital contents reproducing device  220 , which is in a state that the reproduction software is not downloaded) to access the delivery management center  210  via the communication line β to request user registration. The delivery management center  210  processes the interruption program for user registration as shown in  FIG. 8  in accordance with this request, and transmits the data necessary for the user registration to the computer (s 21 ). Thereafter, the user inputs his or her name, address and payment condition, “a bank account number or a credit card number of his or hers, etc.” as displayed in a user registration screen through the operation section  223  of the computer and transmits this registration data to the delivery management center  210  via the communication line β. Then, the delivery management center  210  creates the user ID and the password in accordance with this to register the relevant user ID and the like to the user information DB  214  together with the registration data as user information (s 22 ). On the other hand, the relevant user ID and password are transmitted to the computer of the user via the communication line β (s 23 ). Then, the processing of the interruption program for user registration is finished. The user ID and the password may be inputted by the user himself or herself at the time of user registration. 
     Thereafter, the user operates his or her computer to access the delivery management center  210  and inputs a request for the download of the reproduction software. At this time, the user ID and the password are required. Then, the computer of the user transmits the request to the delivery management center  210  via the communication line β. The delivery management center  210  processes the interruption program for reproduction software download in accordance with this request, reads out the reproduction software and the decryption key c 1  on the software DB  215 , and transmits them to the computer of the user via the communication line β. Then, the reproduction software is downloaded to the memory section  224  of the computer and installed. At the same time, the decryption key c 1  is recorded on the memory section  224 . This makes the computer into the digital contents reproducing device  220 . 
     Next, in order to acquire the contents file, the digital contents reproducing device  220  accesses a contents download address of the delivery management center  210  in accordance with the operation through the user operation section  223  of the user. Then, the delivery management center  210  processes the interruption program for contents download. The data of a contents file list is transmitted to the digital contents reproducing device  220 . The digital contents reproducing device  220  outputs and display the contents file list on the output section  222  based on this data. In order to access the delivery management center  210 , after the reproduction software is executed, the delivery management center  210  may be accessed based on the WEB address recorded together with the relevant software, or may be accessed based on the WEB address that the user has registered in an internet browser. 
     Thereafter, the user selects the contents file to download from the contents file list through the operation section  223 . The data of application for downloading the selected contents file is transmitted to the delivery management center  210 . 
     Upon receiving this application data, the delivery management center  210 , with reference to the contents ID contained in the application data, searches for the contents file corresponding to the relevant contents ID from the digital contents DB  211 , and reads out and transmits it to the digital contents reproducing device  220 . Upon receiving the relevant contents file, the digital contents reproducing device  220  records it on a registry of the memory section  224  or the recording medium set in the reproduction and copy section  225 . At the same time, a file name of the relevant contents file is recorded on a play list of the reproduction software on the memory section  224 . In this manner, the contents file is acquired. The download of the contents file may be acquired by another computer connected to the delivery management center  210  via the communication line β to record it on a recording medium. 
     Thereafter, when the user performs execution operation of the reproduction software with respect to this digital contents reproducing device  220  (in the case where the contents file is recorded on the recording medium, the execution operation of the reproduction software is performed, while the relevant recording medium is set in the reproduction and copy section  225 ), the data of a reproduction player and the play list contained in the relevant reproduction software is outputted and displayed on the output section  222 . Then, the play list is displayed on a screen of the reproducing player (s 1 ). This play list shows a file name of the downloaded contents file and whether or not the relevant contents file is being rented. That is, the contents file with a predetermined flag hoisted, which indicates that a reproduction application has been made, is displayed as the one being rented. Based on this play list, it is determined whether or not the reproducing operation of the contents file being rented has been performed through the operation section  223  (s 2 ). 
     If it is determined that the reproducing operation has not been performed, then it is determined whether or not the application operation for reproduction of the contents file not being rented which is displayed on the play list has been performed through the operation section  223  (s 3 ). As a result, if it is determined that the application operation for reproduction has not been performed, then it is determined whether or not reading operation of the recording medium (operation of DISC LOAD) has been performed through the operation section  223  (s 4 ). When the operation of DISC LOAD is performed, the contents list indicating a contents file on the recording medium which is not recorded on the play list (that is, downloaded on the recording medium with another computer or the like) is outputted and displayed (s 5 ) on the output section  222 . Namely, while the decryption key c 1  on the memory section  225  is read out, the header information a of the contents file on the recording medium is read out and by using the relevant decryption key c 1 , the header information a is decrypted to read out the contents information contained in the relevant header information a, and the contents file with the predetermined flag not hoisted among the contents files on the recording medium is displayed on the contents list. 
     Thereafter, when an application for reproduction of the contents file not being rented on the play list or the contents file on the contents list is performed by the user (s 3  or s 6 ), the decryption key c 1  on the memory section  224  is read out, while the header information a of the relevant contents file on the memory section  224  or on the recording medium is read out and decrypted by using the relevant decryption key c 1 , and based on the WEB address of the contents information contained in this, the contents ID contained in the relevant header information a is transmitted to the delivery management center  210  via the communication line β. In this manner, the execution of the reproduction application processing is transmitted. 
     Then, the delivery management center  210  processes the interruption program for piece data delivery as shown in  FIG. 9 , and transmits the data necessary for the reproduction application processing to the digital contents reproducing device  220  via the communication line β (s 31 ). Based on this data, the digital contents reproducing device  220  outputs and displays a reproduction application screen on the output section  222  (s 7 ). 
     Thereafter, when the user sequentially inputs or selects a rental period through the operation section  223  as displayed on the reproduction application screen (this automatically determines a rental amount of money), and finally inputs the user ID and the password through the operation section  223  as the reproduction application of the contents file (s 8 ), the digital contents reproducing device  220  shifts the display output of the output section  222  to an authentication screen, while the inputted application data is transmitted to the delivery management center  210  via the communication line β. At this time, the contents ID of the contents information on the memory section  224  or on the recording medium and the player ID on the relevant memory section  224  are read out and transmitted to the delivery management center  210  together with the application data (s 9 ). 
     The delivery management center  210  confirms the authentication of the user relating to the application (s 32 ). Namely, with reference to the transmitted user ID and player ID of the user, etc., the user information of the relevant user is read out from the user information DB  214 , and whether or not the relevant user is an authentic user is confirmed. At this time, the delivery management center  210  has in advance prepared a list of inappropriate persons with nonpayments of rental fee more than or equal to predetermined times or the like in the user information DB  214 , and in addition to the authentication, confirms whether or not the user falls under the list of inappropriate persons (this confirmation of the list of inappropriate persons is arbitrary). 
     In the case where the delivery management center  210  has confirmed that the user relating to the application is an unauthentic user or an authentic user but a person who falls under the list of inappropriate persons, the rejection of the application of the user is transmitted to the digital contents reproducing device  220  via the communication line β (s 33 ). Then, the interruption program for piece data delivery is finished. 
     On the other hand, in the case where it has been confirmed that the user relating to the application is an authentic user and a person who does not fall under the list of inappropriate persons, with reference to the player ID of the user or the like, accounting is recorded on the user information of the user on the user information DB  214 , while with reference to the contents ID, the piece data DB  216  is searched to read out the piece data d and the decryption key c 2  corresponding to the relevant contents ID and to transmit them to the digital contents reproducing device  220  as a reply indicating that the application of the user is accepted together with the rental information contained in this reproduction application data via the communication line β (s 34 ). Then, the processing of the interrupt program for piece data delivery is finished. 
     The charge is charged to a bank/credit card company  230  or charged directly to the user, based on the user information DB  214  for every predetermined period and the user transfers the charge to an account or pays it in a convenience store or the like. Furthermore, in the case where the delivery management center  210  is connected to the bank/credit card company  230  via the communication line β, it is obviously possible to immediately settle accounts, too. 
     Thereafter, upon receiving the rejection of the application of the user via the communication line β (s 10 ), the digital contents reproducing device  220  outputs and displays an error message to the output section  222  (s 11 ). 
     On the other hand, when the piece data d and the decryption key c 2 , and the rental information are received via the communication line β (s 10 ), the predetermined flag is hoisted, while the piece data d, the decryption key c 2  and the rental information are recorded on the memory section  224  (s 12 ). At the same time, by using a clock function of the computer, a piece data transmission date and time is recorded on the memory section  224 . Then, the play list is updated, and outputted and displayed on the output section  222 , so that a file name of the contents file with the piece data d obtained is displayed on the relevant play list (s 1 ). 
     Thereafter, when the reproducing operation of the contents file being rented is performed based on the play list through the operation section  223  (s 2 ), the digital contents reproducing device  220  reads out the decryption key c 1  from the memory section  224 , and meanwhile, it reads out the header information a of the contents file on the memory section  224  or on the recording medium and decrypts the header information a by using the decryption key c 1 . Then, the data body b on the memory section  224  or on the recording medium is read out by using the reproduction information contained in the relevant header information a and is reproduced while being decrypted with the decryption key c 2  on the memory section  224  (s 13 ). In addition, while the starting location information of the data body b on the memory section  224  or on the recording medium is read out, the piece data d on the memory section  224  is read out and the counting of a data length or a time from the starting location information to the location information contained in the piece data d is started (s 14 ). Thereafter, whether or not the counting is finished is determined (s 15 ). Thereby, the omitted part of the data body b is recognized. As a result of this determination, when it is determined that the counting is finished and the omitted part of the data body b is recognized, the piece data d on the memory section  224  is read out and the omitted data contained in the relevant piece data d is read out as the data of the omitted part of the relevant data body b and is reproduced while being decrypted with the decryption key c 2  on the memory section  224  (s 16 ). Then, the data body b on the memory section  224  or on the recording medium is read out again and is subsequently reproduced while being decrypted with the decryption key c 2  on the memory section  224  (s 17 ). This reproduction software program is finished upon end processing by the user. 
     Furthermore, the reproduction software, in addition to the above-described basic function, has a piece data management function which is resident in the relevant digital contents reproducing device  220  to manage the piece data d when the digital contents reproducing device  220  is turned ON. This piece data management function manages the piece data d on the memory section  224 , While it obtains a difference between a piece data transmission data and time and a current date and time as an elapsed period from a time point when the piece data d is transmitted, and when this reaches the rental period contained in the rental information, it is determined to be outside of the rental period and the piece data d and the decryption key c 2  on the memory section  224  are deleted, and the predetermined flag is hauled down. 
     Thus, in this system  200 , even when the user operates to reproduce the contents file by using the digital contents reproducing device  220 , the data body b of the contents file cannot be reproduced unless the user obtains the piece data d from the delivery management center  210  as an authentic reproduction applicant. Accordingly, the temporary, illegal use of the contents can be prevented. In addition, with respect to the contents file whose rental period has passed, the piece data d is deleted, which can also prevent secondary illegal use. Furthermore, even if the contents file is copied to another recording medium by the user, since in the contents file recorded on this recording medium, the reproduction information contained in the header information a is omitted, the contents file cannot be reproduced unless the user obtains the piece data d as an authentic reproduction user. Therefore, tertiary, illegal use can also be prevented. 
     Furthermore, outside of the rental period of the digital contents, only the piece data d or the like on the memory section  224  is deleted automatically, and the contents file remains as it is. Thus, inside and outside of the rental period, the contents file can be copied to another recording medium by using the digital contents reproducing device  220 . In order to reproduce such a contents file on the recording medium, authentication to the delivery management center  210  and payment of rental fee by using the digital contents reproducing device  220  are required, so that the collection of charge in accordance with the secondary and tertiary use can be ensured. 
     Moreover, in this system, since the contents file can be easily recorded on the recording medium by using computer having a write function as described above, a rental video shop or the like can employ a form of setting up the relevant computer instead of displaying recording media such as video tapes, CD and DVD. This makes it unnecessary to return the recording medium, which brings advantages to both the agency and customers. In addition, since a shop clerk does not know what contents file a customer downloads, some kinds of digital contents become easy to rent. In this case, it goes without saying that a form of a rental video shop need not be employed but a form of a service by an internet cafe can be employed. The contents DB may be set up in the rental video shop or the internet cafe. 
     This illegal use preventing system  200  may be subject to any design modification as long as it comprises delivery management means which is a server having a first database on which a contents file with a header information and a data body is recorded with part of the relevant data body omitted and a second database on which this omitted data and location information indicating in which part of the data body the relevant omitted data is located is recorded, and which can deliver the relevant contents file via a communication line, and meanwhile manages the utilization of the relevant contents file, and a digital contents reproducing device which can intercommunicate with this delivery management means via the communication line, and which is used in reproducing the contents file delivered from the delivery management means, wherein when a request for download of the contents file is inputted to the digital contents reproducing device by a user, the digital contents reproducing device transmits the relevant request to the delivery management means via the communication line, the delivery management means transmits the contents file relating to the relevant request to the digital contents reproducing device via the communication line, and the digital contents reproducing device receives the relevant contents file to record it on the memory section or on the recording medium, while when an application for reproduction of the contents file is inputted to the digital contents reproducing device by the user, the digital contents reproducing device transmits the relevant application to the delivery management means via the communication line, the delivery management means transmits omitted data and its location information of the contents file relating to the relevant application simultaneously or sequentially to the digital contents reproducing device via the communication line, and the digital contents reproducing device receives the relevant omitted data and its location information simultaneously or subsequently to record it on the memory section and reads out the data body of the contents file on the memory section or on the recording medium to reproduce it, and at the same time, the digital contents reproducing device recognizes the omitted part of the data body with reference to the location information read out from the memory section, and reads out and reproduces the omitted data on the memory section as the data of the relevant omitted part. 
     Therefore, although the delivery management center  210  is designed to have one digital contents DB  211 , it may have a plurality of digital contents DBs. In this case, the design may be such that different kinds of contents file groups are stored in the respective DBs, for example, contents files of movie are stored in a first DB and content files of music are stored in a second DB, or such that the contents file groups stored in the respective DBs are the same and the concentration of access on a first DB during busy hours is prevented. It is true of the piece data DB  216 . Furthermore, although the delivery management center  210  is designed to have the digital contents DB  211  and the piece data DB  216 , the digital contents DB  211  and the piece data DB  216  can also be set up in a different place from the delivery management center  210 . In this case, the delivery management center  210  may authenticate the user and transmit a WEB address of the digital contents DB  211  and the piece data DB  216  to the digital contents reproducing device  220 , and the digital contents reproducing device  220  may access the digital contents DB  211  and the piece data DB  216  based on the relevant WEB address to obtain the contents file and the piece data d. 
     Furthermore, although the digital contents DB  211  has the header information a and the data body b recorded in an encrypted state, respectively, it is arbitrary whether or not the encryption is performed. However, it is desirable that at least the data body b is encrypted. Furthermore, while the contents file is structured to have the header information a and the data body b, it is obviously possible to record the contents file with other information added thereto. Other information includes a program by which it is determined whether or not the reproduction software has been installed in the computer of the user, and when it is determined that the reproduction software has not been installed, HP of the delivery management center  210  is automatically accessed, and the like. When this program has been recorded and the user attempts to execute the contents file which he or she has in advance obtained in his or her computer (computer equivalent to the digital contents reproducing device  220 , which is in a state that the reproduction software is not downloaded), the WEB address of the delivery management center  210  is read out, and based on this, the delivery management center  210  is automatically accessed. Thereafter, the reproduction software can be obtained by the above-described procedure. Although the contents file is designed such that a part thereof is omitted, it can be obviously designed such that a plurality of points are omitted. 
     While the location information is designed to be a data length or a time from the starting location information to the omitted part, it may be an address value indicating the omitted part or the like. In this case, it is sequentially determined whether or not an address value of the data body b on the recording medium for distribution α to be read out next and the location information coincide with each other and as a result of the determination, when they are determined not to coincide with each other, the data body b on the memory section  224  or on the recording medium which the address value indicates is read out, while when they are determined to coincide with each other, the omitted data on the memory section  224  is read out. 
     While the piece data d consists of the omitted data body and the location information, whether or not the location information is contained is arbitrary. In this case, for example, omitted location information indicating the omitted part is in advance recorded before the omitted part of the data body b, and the data body b is reproduced, and further counting is performed from the starting location information to the omitted location information. When this counting is finished, the omitted data on the memory section  224  may be reproduced as the data of the relevant omitted part. Alternatively, a location of the omitted part of the data body b is predetermined, and the location information of the omitted data is prepared in the reproduction software. It is possible that the data body b is reproduced and that at the same time, the omitted part of the data body b is recognized based on this location information to reproduce the omitted data on the memory section  224  as the data of the relevant omitted part. 
     Thus, the contents of the reproduction software are only one example, and any modification in design can be made as long as similar contents can be realized. It is true of the interruption program for user registration, the interruption program for reproduction software download, and the interruption program for piece data delivery. 
     Furthermore, in the case where the contents file is recorded on the memory section  224  of the digital contents reproducing device  220 , after the rental period has passed, the contents file may be deleted together with the piece data d, or separately from the piece data d, an elapsed time from a point of time when the contents file is received is obtained and when the relevant elapsed time reaches a predetermined period, the relevant contents file may be deleted. 
     In the second embodiment, the system can also be changed in design so as to prevent illegal use of a contents file which is not delivered on a rental basis but transferred for pay or for free. In this case, advantages similar to the foregoing are also brought about. In the contents of the reproduction software used in this case, only the processing when the delivered contents file is outside of the rental period is deleted. Furthermore, as for the digital contents reproducing device  220 , the reproduction software may not be downloaded from the delivery management center  210 , but may be installed through a recording medium such as CD. Furthermore, obviously, the digital contents reproducing device  220  is not a computer but can be a dedicated device. 
     Embodiment 3 
     Next, a third embodiment of the present invention is described with reference to the drawings.  FIG. 10  is a configuration diagram of a digital contents illegal use preventing system relating to the third embodiment of the present invention,  FIG. 11  is a flowchart of reproduction software used for the digital contents illegal use preventing system, and  FIG. 12  is a flowchart of an interruption program for contents download. 
     A digital contents illegal use preventing system  300  as shown in  FIG. 10  has the same configuration as that of the illegal use preventing system  200 . Different points are the contents of reproduction software recorded on a memory section  324  of a digital contents reproducing device  320  (refer to  FIG. 11 ) and the contents of the interruption program for contents download recorded on a memory section  317  of a delivery management center  310  (refer to  FIG. 12 ). Hereinafter, the different points are described in detail, and a description of overlapping parts is omitted. 
     The reproduction software is downloaded to the digital contents reproducing device  320  and recorded on the memory section  324  by procedure similar to that of Embodiment 2. 
     Next, in order to acquire a contents file, the digital contents reproducing device  320  accesses a contents download address of the delivery management center  310  in accordance with the operation through a user operation section  323  of the user. Then, the delivery management center  310  processes the interruption program for contents download as shown in  FIG. 12 . The data of a contents file list necessary for rental application processing and the like are transmitted to the digital contents reproducing device  320  via the communication line β (s 21 ). The digital contents reproducing device  320  outputs and displays a rental application screen on an output section  322  based on this data. 
     Thereafter, when the user sequentially inputs or selects the contents file and a rental period thereof through the operation section  323  as displayed on the reproduction application screen (this automatically determines a rental amount of money), and finally inputs a user ID and a password through the operation section  323  as a rental application of the contents file, the digital contents reproducing device  320  shifts the display output of the output section  322  to an authentication screen, while the inputted application data is transmitted to the delivery management center  310  via the communication line β. At this time, a player ID on the memory section  324  is read out and transmitted to the delivery management center  310  together with the application data. 
     The delivery management center  310  confirms the authentication of the user relating to the application (s 22 ). Namely, with reference to the transmitted user ID and player ID of the user, etc., the user information of the relevant user is read out from a user information DB  314 , and whether or not the relevant user is an authentic user is confirmed. At this time, the delivery management center  310  has in advance prepared a list of inappropriate persons with nonpayments of rental fee more than or equal to predetermined times or the like in the user information DB  314 , and in addition to the authentication, confirms whether or not the user falls under the list of inappropriate persons (this confirmation of the list of inappropriate persons is arbitrary). 
     In the case where the delivery management center  310  has confirmed that the user relating to the application is an unauthentic user or an authentic user but a person who falls under the list of inappropriate persons, the rejection of the application of the user is transmitted to the digital contents reproducing device  320  via the communication line β (s 23 ). 
     On the other hand, in the case where it has been confirmed that the user relating to the application is an authentic user and a person who does not fall under the list of inappropriate persons, with reference to the contents ID, the selected contents file is searched and read out from a digital contents DB  311 , while the piece data d and the decryption key c 2  corresponding to the relevant contents ID are searched and read out from a piece data DB  316 , and the contents file, the piece data d and the decryption key c 2  are sequentially transmitted to the digital contents reproducing device  320  as a reply indicating that the application of the user is accepted together with the rental information via the communication line β (s 24 ). Then, with reference to the player ID of the user and the like, accounting is recorded on the user information on the user information DB  314  of the relevant user. 
     The accounting is summed up based on the user information DB  314  for every predetermined period, and is charged to a bank/credit card company  330  or charged directly to the user, so that the user transfers the charge to an account or pays it in a convenience store or the like. Furthermore, in the case where the delivery management center  310  is connected to the bank/credit card company  330  via the communication line β, it is obviously possible to immediately settle accounts, too. 
     Thereafter, upon receiving the rejection of the application of the user via the communication line β, the digital contents reproducing device  320  outputs and displays an error message to the output section  322 . 
     On the other hand, when the relevant contents file and the like are received via the communication line β, the relevant contents file is recorded on a registry of the memory section  324  or on a recording medium set in a copy section  325 , while the piece data d, the decryption key c 2  and the rental information are recorded on a predetermined registry for piece data different from the registry on which the contents file of the memory section  324  is recorded. At the same time, a file name of the relevant contents file is recorded on a play list of the reproduction software on the memory section  324 . Then, a predetermined flag is hoisted. 
     Thereafter, when the user performs execution operation of the reproduction software (in the case where the contents file is recorded on the recording medium, the execution operation for the reproduction software is performed, while the relevant recording medium is set), the data of a reproduction player and the play list contained in the relevant reproduction software is outputted and displayed on the output section  322 . Then, the play list is displayed on a screen of the reproduction software (s 1 ). This play list shows a file name of the contents file and whether or not the relevant contents file is being rented. That is, the contents file with a predetermined flag hoisted is displayed as the one being rented. Based on this play list, it is determined whether or not the reproducing operation of the contents file being rented has been performed through the operation section  323  (s 2 ). 
     If it is determined that the reproducing operation has not been performed, then it is determined whether or not the application operation of the contents file not being rented has been performed through the operation section  323  based on the play list (s 3 ). Namely, it is determined whether or not the re-rental of the contents file whose rental period has been finished is applied for. As a result, if it is determined that the application for reproduction has been performed, then the decryption key c 1  on the memory section  324  is read out, while the header information a of the relevant contents file on the memory section  324  or on the recording medium is read out and by using the relevant decryption key c 1 , the header information a is decrypted and based on a WEB address of the contents information contained in the relevant header information a, the contents ID is transmitted to the delivery management center  310  as a notice that the reproduction application processing is performed via the communication line β. 
     Then, the delivery management center  310  processes an interruption program for piece data delivery (refer to  FIG. 9 ). Then, the delivery management center  310  transmits data necessary for the reproduction application processing to the digital contents reproducing device  320  via the communication line β (s 31 ). Based on this data, the digital contents reproducing device  320  outputs and displays a reproduction application screen on the output section  322  (s 4 ). 
     Thereafter, when the user sequentially inputs or selects a rental period through the operation section  323  as displayed on the reproduction application screen (this automatically determines a rental amount of money), and finally inputs the user ID and the password through the operation section  323  as the reproduction application of the contents file (s 5 ), the digital contents reproducing device  320  shifts the display output of the output section  322  to an authentication screen, while the inputted application data is transmitted to the delivery management center  310  via the communication line β. At this time, the contents ID of the contents information on the memory section  324  or on the recording medium and the player ID on the memory section  324  are read out and transmitted to the delivery management center  310  together with the application data (s 6 ). 
     The delivery management center  310  confirms the authentication of the user relating to the application (s 32 ). Namely, with reference to the transmitted user ID and player ID of the user, etc., the user information of the relevant user is read out from the user information DB  314 , and whether or not the relevant user is an authentic user is confirmed. At this time, the delivery management center  310  has in advance prepared a list of inappropriate persons with nonpayments of rental fee more than or equal to predetermined times or the like in the user information DB  314 , and in addition to the authentication, confirms whether or not the user falls under the list of inappropriate persons (this confirmation of the list of inappropriate persons is arbitrary). 
     In the case where the delivery management center  310  has confirmed that the user relating to the application is an unauthentic user or an authentic user but a person who falls under the list of inappropriate persons, the rejection of the application of the user is transmitted to the digital contents reproducing device  320  via the communication line β (s 33 ). Then, the interruption program for piece data delivery is finished. 
     On the other hand, in the case where it has been confirmed that the user relating to the application is an authentic user and a person who does not fall under the list of inappropriate persons, with reference to the player ID of the user or the like, accounting is recorded on the user information of the user on the user information DB  314 , while the piece data DB  316  is searched to read out the piece data d and the decryption key c 2  corresponding to the above-mentioned contents ID, and to transmit them to the digital contents reproducing device  320  as a reply indicating that the application of the user is accepted together with the rental information contained in this reproduction application data via the communication line β (s 34 ). Then, the processing of the interrupt program for piece data delivery is finished. The billing is performed in a manner similar to the foregoing. 
     Thereafter, upon receiving the rejection of the application of the user via the communication line β (s 7 ), the digital contents reproducing device  320  outputs and displays an error message to the output section  322  (s 8 ). 
     On the other hand, when the piece data d and the decryption key c 2 , and the rental information are transmitted as a replay that the application of the user is accepted from the delivery management center  310  via the communication line β (s 7 ), the predetermined flag is hoisted, while the piece data d, the decryption key c 2  and the rental information are recorded on the above-described registry for piece data on the memory section  324  (s 9 ). At the same time, by using a clock function of the computer, a piece data transmission date and time is recorded on the memory section  324 . Then, the play list is updated, and outputted and displayed on the output section  322  so as to indicate the contents file with the piece data d acquired is being rented (s 1 ). 
     Thereafter, when the reproducing operation of the contents file being rented is performed based on the play list through the operation section  323  (s 2 ), the digital contents reproducing device  320  reads out the decryption key c 1  from the memory section  324 , and meanwhile, it reads out the header information a of the contents file on the memory section  324  or on the recording medium and decrypts the header information a by using the relevant decryption key c 1 . Then, the data body b on the memory section  324  or on the recording medium is read out by using the reproduction information contained in the relevant header information a and is reproduced while being decrypted with the decryption key c 2  on the memory section  324  (s 10 ). In addition, while starting location information of the data body b on the memory section  324  or on the recording medium is read out, the piece data d on the memory section  324  is read out to start counting of a data length or a time from the starting location information to the location information contained in the piece data d (s 11 ). Thereafter, whether or not the counting is finished is determined (s 12 ). Thereby, the omitted part of the data body b is recognized. As a result of this determination, when it is determined that the counting is finished and the omitted part of the data body b is recognized, the piece data d on the memory section  324  is read out and the omitted data contained in the relevant piece data d is read out as the data of the omitted part of the relevant data body b and is reproduced while being decrypted with the decryption key c 2  on the memory section  324  (s 13 ). Then, the data body b on the memory section  324  or on the recording medium is read out again and is subsequently reproduced while being decrypted with the decryption key c 2  on the memory section  324  (s 14 ). This reproduction software program is finished upon end processing by the user. 
     Furthermore, the reproduction software, in addition to the above-described basic function, has a piece data management function which is resident in the relevant digital contents reproducing device  320  to manage the piece data d when the digital contents reproducing device  320  is turned ON. This piece data management function manages the piece data d on the memory section  324 , while it obtains a difference between a piece data transmission data and time and a current date and time as an elapsed period from a time point when the piece data d is transmitted, and when this reaches the rental period contained in the rental information, it is determined to be outside of the rental period and the piece data d and the decryption key c 2  on the memory section  324  are deleted and the predetermined flag is hauled down. 
     In the above-described illegal use preventing system  300 , since the piece data d can be obtained in concurrence with the contents file, the authentic temporary use of the contents file becomes easier as compared with Embodiment 2. In addition, with respect to the contents file whose rental period has passed, the piece data d is deleted, which can also prevent secondary illegal use. Furthermore, even if the contents file is recorded on the recording medium by the user, since in this contents file recorded on this recording medium, the reproduction information contained in the header information a is omitted, the contents file cannot be reproduced unless the user obtains the piece data d as an authentic reproduction user. Therefore, tertiary, illegal use can also be prevented. 
     Furthermore, outside of the rental period of the digital contents, only the piece data d and the like on the memory section  324  are deleted automatically, and the contents file remains as it is. Thus, outside of the rental period, the contents file can be copied to another recording medium by using the digital contents reproducing device  320 . In order to reproduce such a contents file on the recording medium, authentication to the delivery management center  310  and payment of rental fee by using the digital contents reproducing device  320  are required, so that the collection of charges in accordance with the secondary and tertiary use can be ensured. 
     Although the delivery management center  310  is designed to have one digital contents DB  311 , it may have a plurality of digital contents DBs. In this case, the design may be such that different kinds of contents file groups are stored in the respective DBs, for example, contents files of movie are stored in a first DB and content files of music are stored in a second DB, or such that the contents file groups stored in the respective DBs are the same and the concentration of access on a first DB during busy hours is prevented. It is true of the piece data DB  316 . Furthermore, although the delivery management center  310  is designed to have the digital contents DB  311  and the piece data DB  316 , the digital contents DB  311  and the piece data DB  316  can also be set up in a different place from the delivery management center  310 . In this case, the delivery management center  310  may authenticate the user and transmit a WEB address of the digital contents DB  311  and the piece data DB  316  to the digital contents reproducing device  320 , and the digital contents reproducing device  320  may access the digital contents DB  311  and the piece data DB  316  based on the relevant WEB address to obtain the contents file and the piece data d. 
     Furthermore, although the digital contents DB  311  has the header information a and the data body b recorded in an encrypted state, respectively, it is arbitrary whether or not the encryption is performed. However, it is desirable that at least the data body b is encrypted. 
     Furthermore, while the contents file is structured to have the header information a and the data body b, it is obviously possible to record the contents file with other information added thereto. Other information includes a program by which it is determined whether or not the reproduction software has been installed in the computer of the user, and when it is determined that the reproduction software has not been installed, HP of the delivery management center  310  is automatically accessed, and the like. When this program has been recorded and the user attempts to execute the contents file which he or she has in advance obtained in his or her computer (computer equivalent to the digital contents reproducing device  320 , which is in a state that the reproduction software is not downloaded), the WEB address of the delivery management center  310  is read out, and based on this, the delivery management center  310  is automatically accessed. Thereafter, the reproduction software can be obtained by the above-described procedure. Although the contents file is designed such that a part thereof is omitted, it can be obviously designed such that a plurality of points are omitted. 
     While the location information is designed to be a data length or a time from the starting location information to the omitted part, it may be an address value indicating the omitted part or the like. In this case, it is sequentially determined whether or not an address value of the data body b on recording medium for distribution α to be read out next and the location information coincide with each other, and when they are determined not to coincide with each other, the data body b on the memory section  324  or on the recording medium which the address value indicates is read out, while when they are determined to coincide with each other, the omitted data on the memory section  324  is read out. 
     While the piece data d consists of the omitted data body and the location information, whether or not the location information is contained is arbitrary. In this case, for example, omitted location information indicating the omitted part is in advance recorded before the omitted part of the data body b, and the data body b is reproduced, and further counting is performed from the starting location information to the omitted location information. When this counting is finished, the omitted data on the memory section  324  may be reproduced as the data of the relevant omitted part. Alternatively, a location of the omitted part of the data body b is predetermined, and the location information of the omitted data is prepared in the reproduction software. It is possible that the data body b is reproduced and that at the same time, the omitted part of the data body b is recognized based on this location information to reproduce the omitted data on the memory section  324  as the data of the relevant omitted part. 
     Thus, the contents of the reproduction software are only one example, and any modification in design can be made as long as similar contents can be realized. Furthermore, with respect to the contents of the interruption program for contents file download, any modification in design can be made as long as the contents are such that according to the application for downloading the contents file, the piece data d is downloaded together with, or separately from the contents file. It is true of the interruption program for user registration, the interruption program for reproduction software download, and the interruption program for piece data delivery. 
     Furthermore, in the case where the contents file is recorded on the memory section  324  of the digital contents reproducing device  320 , after the rental period has passed, the contents file may be deleted together with the piece data d, or separately from the piece data d, an elapsed time from a point of time when the contents file is received is obtained and when the relevant elapsed time reaches a predetermined period, the relevant contents file may be deleted. 
     In the third embodiment, the system can also be changed in design so as to prevent illegal use of a contents file which is not delivered on a rental basis but transferred for pay or for free. In this case, advantages similar to the foregoing are also brought about. In the contents of the reproduction software used in this case, only the processing when the delivered contents file is outside of the rental period is deleted. Furthermore, as for the digital contents reproducing device  320 , the reproduction software may not be downloaded from the delivery management center  310 , but may be downloaded through a recording medium such as CD. Furthermore, obviously, the digital contents reproducing device  320  is not a computer but can be a dedicated device. 
     Embodiment 4 
     Next, a fourth embodiment of the present invention is described with reference to the drawings.  FIG. 13  is a configuration diagram of a digital contents illegal use preventing system relating to the fourth embodiment of the present invention,  FIG. 14  is a flowchart of reproduction software used for this system,  FIG. 15  is diagrams showing a contents file of this system,  FIG. 15A  being an image diagram of a data body and  FIG. 15B  being an image diagram of a part a of the data body, and  FIG. 16  is a flowchart of recording medium creating software executed by a computer which is a device for creating a recording medium for distribution used in this system. 
     A digital contents illegal use preventing system  400  as shown in  FIG. 13  has the same configuration as that of the illegal use preventing system  100 . Different points are the configuration of the contents file recorded on the recording medium for distribution α and the contents of reproduction software recording on an auxiliary storage section  425  of a digital contents reproducing device  420  (refer to  FIG. 14 ). Hereinafter, the different points are described in detail, and a description of overlapping parts is omitted. 
     The digital contents reproducing device  420  is a general-purpose computer used by a user. In the figure, reference numeral  421  denotes a control section such as CPU, reference numeral  422  denote an output section such as a monitor and a speaker, reference numeral  423  denotes an operation section such as a keyboard and a mouse, reference numeral  424  denotes a reproduction and copy section reading/writing the data with respect to the recording medium for distribution α and the like, and reference numeral  425  denotes an auxiliary storage section such as a hard disk, and reference numeral  426  denotes a main storage section such as DRAM, and reference numeral  427  denotes a communication section for performing communication which is connected to the communication line β. 
     On the auxiliary storage section  425 , in addition to basic programs such as an operation system as a computer, the reproduction software as shown in  FIG. 14  is recorded. The contents of the reproduction software will be described later. The processing of this software on the main storage section  426  by the control section  421  allows a function to be exerted as the digital contents reproducing device  420  in which the data body b recorded on the recording medium for distribution α is sequentially transferred to the main storage section  426  by the decryption bit length, and the relevant data on the main storage section  426  is sequentially decrypted by the decryption bit length and is returned from a compressed state to an original state for reproducing (reading). 
     The contents file on the recording medium for distribution a has the header information a and the data body b which is compressed in a compressing method such as MPEG and is subjected to well-known encryption, wherein part of the relevant data body b is omitted, the relevant omitted part is closed to continue the data body b, and dummy data with the same bit length as that of the omitted part is added to the end thereof (refer to  FIG. 15 ). The control section  142  of the device for creating a recording medium for distribution  140  of Embodiment 1 processes a program on the memory  145  shown in  FIG. 16  to thereby create this recording medium for distribution α. The header information a of the contents file is first read out from a master disk set in the input section  141 , only reproduction information contained in the relevant header information a is encrypted and the relevant header information a is recorded on a recording medium such as DVD set in the recording section  143  (s 1 ). Next, the data body b of the contents file is read out from the master disk (s 2 ), is compressed (s 3 ) and is encrypted (s 4 ). Thereafter, part of the relevant data body b is separated (s 5 ). In the case where a plurality of points of the data body b are separated, with the data of the decryption bit length to be transferred to the main storage section  426  defined as one block, a part is separated from the relevant one block of data (s 5 ). Then, the relevant separated omitted data is recorded on the piece data memory  144  as the piece data d together with location information thereof (s 6 ). Meanwhile, the omitted part of the relevant data body b is closed to continue the relevant data body b (s 7 ) and the dummy data with the same bit length as that of the omitted part is read out from the memory section  145  to add it to the end of the relevant data body b (s 8 ). In the case where the data body b is omitted at a plurality of points, the dummy data having a bit length of the bit length of the omitted data×the number of omitted points is added to the end of the data body b (s 8 ). The relevant data body b is recorded on the recording medium such as DVD set in the recording section  143  (s 9 ). This finishes the processing of this software. In the case where a plurality of points of the data body b are separated, the separation can be also performed so that the data of the decryption bit length is not of one block. 
     The bit length of the omitted data is a bit length different from the decryption bit length, and a bit length different from divisors of the relevant decryption bit length. In the case where the data body b is omitted at a plurality of points, the bit length of the omitted data×the number of omitted points is a bit length different from the divisors of the decryption bit length. For example, when the decryption bit length is set at 10 bytes (that is, 80 bits), the bit length of the omitted data is set at 10 bytes, and 7 bytes (that is, 56 bits) and 13 bytes (that is, 104 bits) which are bit lengths of byte numbers other than the divisors, and the like. When the bit length of the omitted data is set at 7 bytes, the data body b are not omitted at 10 and 20 points. These are because when the decryption bit length is 10 bytes, if the bit length of the omitted data is set at 20 bytes, a data row of the data of the decryption bit length after the omitted part makes no difference between before and after omitting the omitted data, and as a result, the data body b after the omitted part can be reproduced. Furthermore, when the omitted data with the bit length of 7 bytes is omitted at 10 points, a data row of the decryption bit length after the tenth omitted part of the data body b makes no difference between before and after the omitted data is omitted, and as a result, there arises a possibility that the data body b after the tenth omitted part is reproduced. 
     A description of a digital contents illegal use preventing method using the digital contents reproducing device  420  of the digital contents illegal use preventing system  400  configured as described above is given and in conjunction of this, the operation of a management center  410 , the operation of the digital contents reproducing device  420 , and the contents of the respective programs are described. The decryption keys c 1 , c 2  are recorded on a piece data DB  441  of the management center  410 . Hereinafter, for convenience, a case where one point of the data body b is omitted is described. 
     In the digital contents reproducing device  420 , the reproduction software is downloaded by the same procedure as that of Embodiment 1 and is recorded on the auxiliary storage section  425 . 
     When the recording medium for distribution α is set in the reproduction and copy section  424  by the user and the execution of the reproduction software is operated, this digital contents reproducing device  420  reads out the relevant reproduction software from the auxiliary storage section  425  to the main storage section  426  for processing, and reads out the data such as a reproduction player, a play list contained in the relevant reproduction software on the main storage section  426  to output and display it on the output section  422 . Then, the play list showing a content file being rented is displayed on a screen of the relevant reproducing player (s 1 ). Namely, the contents file having a predetermined flag hoisted, which indicates that a reproduction application has been made, is displayed on the play list. Then, based on this play list, whether or not reproducing operation has been performed is determined through the operation section  423  (s 2 ). 
     When it is determined that the reproducing operation has not been performed, it is determined whether or not reading operation (operation of DISC LOAD) of the recording medium for distribution α has been performed through the operation section  423  (s 3 ). When the operation of DISC LOAD is performed, a contents list showing a contents file for which reproduction application has not been made is read out on the main storage section  426  and is outputted and displayed on the output section  422  (s 4 ). Namely, contents information contained in the header information a of the contents file with a predetermined flag not hoisted among the contents files on the recording medium for distribution α is read out on the main storage section  426  and is displayed on the contents list. 
     Thereafter, when an application for reproduction of the contents file on the contents list is performed by the user, the contents information contained in the header information a of the relevant contents file on the recording medium for distribution α is read out on the main storage section  426 . Then, based on a WEB address contained in the relevant contents information, a contents ID contained in the relevant contents information is transmitted to the management center  410  via the communication line β. In this manner, the execution of the reproduction application is transmitted. 
     The management center  410  processes the interruption program for piece data delivery (take over and refer to  FIG. 4 ). Then, the data necessary for the reproduction application processing is read out from the memory section  416  and is transmitted to the digital contents reproducing device  420  via the communication line β (s 31 ). Based on this data, the digital contents reproducing device  420  reads out the data of a reproduction application screen on the main storage section  426  to output and display it on the output section  422  (s 5 ). 
     Thereafter, when the user sequentially inputs or selects a rental period through the operation section  423  as displayed on the reproduction application screen (this determines a rental amount of money), and finally inputs a user ID and a password through the operation section  423  as a reproduction application of the recording medium for distribution α (s 6 ), the digital contents reproducing device  420  transmits the inputted application data to the management center  410  via the communication line β. At this time, the contents ID contained in the contents information of the header information a on the recording medium for distribution α and the player ID on the auxiliary storage section  425  are read out on the main storage section  426 , and transmitted to the management center  410  together with the application data (s 7 ). 
     Upon receiving the relevant application data and the like, the management center  410  confirms the authentication of the user relating to the relevant application (s 32 ). Namely, with reference to the received user ID and player ID of the user, etc., the user information of the relevant user is read out from a user information DB  414 , and whether or not the relevant user is an authentic user is confirmed. At this time, the management center  410  has in advance prepared a list of in appropriate persons with nonpayments of rental fee more than or equal to predetermined times or the like in the user information DB  414 , and in addition to the authentication, confirms whether or not the user falls under the list of inappropriate persons (this confirmation of the list of inappropriate persons is arbitrary). 
     In the case where the management center  410  has confirmed that the user relating to the application is an unauthentic user or an authentic user but a person who falls under the list of inappropriate persons, the rejection of the application of the user is transmitted to the digital contents reproducing device  420  via the communication line β (s 33 ). Then, the interruption program for piece data delivery is finished. 
     On the other hand, in the case where it has been confirmed that the user relating to the application is an authentic user and a person who does not fall under the list of inappropriate persons, with reference to the player ID of the user or the like, accounting is recorded on the user information of the user on the user information DB  414 , while with reference to the contents ID, a piece data DB  111  is searched to read out the decryption keys c 1 , c 2  and the piece data d corresponding to the relevant contents ID, and to transmit them to the digital contents reproducing device  420  as a reply indicating that the application of the user is accepted together with the rental information indicating the rental period and the like which are contained in the application data via the communication line β (s 34 ). Then, the processing of the interrupt program for piece data delivery is finished. 
     The accounting is summed up based on the user information DB  414  for every predetermined period, and is charged to a bank/a credit card company  430  or charged directly to the user, so that the user transfers the charge to an account or pays it in a convenience store or the like. Furthermore, in the case where the management center  410  is connected to the bank/credit card company  430  via the communication line β, it is obviously possible to immediately settle accounts, too. 
     Thereafter, when the digital contents reproducing device  420  receives the rejection of the application of the user via the communication line β (s 8 ), it outputs and displays data of an error message contained in the data of the rejection on the output section  422  (s 9 ). On the other hand, when the decryption keys c 1 , c 2 , the piece data d and the rental information are received via the communication line β (a 8 ), the predetermined flag is set, while the decryption keys c 1 , c 2 , the piece data d and the rental information are recorded on the memory section  425  (s 10 ). At the same time, by using a clock function of the computer, a piece data transmission date and time is recorded on the auxiliary storage section  425 . Then, the play list is read out on the main storage section  426  for updating, and is outputted and displayed on the output section  422  (s 1 ). This allows a file name of the contents file with the piece data d obtained to be displayed on the play list. 
     Thereafter, when the reproducing operation of the contents file is performed based on the play list through the operation section  423  (s 2 ), the digital contents reproducing device  420  reads out the reproduction information contained in the header information a relating to the relevant contents file on the recording medium for distribution α on the main storage section  426 , while it reads out the decryption key c 1  from the auxiliary storage section  425  and decrypts the relevant reproduction information by using the relevant decryption key c 1 . Then, by using the relevant reproduction information, the data body b on the recording medium for distribution α is sequentially read out by the decryption bit length on the main storage section  426 , and at the same time, the decryption key c 2  is read out from the auxiliary storage section  425  on the main storage section  426 . Thereby, the relevant data on the main storage section  426  is sequentially decrypted by the decryption bit length by using the decryption key c 2  and the relevant data is sequentially returned from the compressed state to the original state through a filter of MPEG or the like, which reproduces the data body b (s 11 ). 
     In conjunction with this processing at step  11 , the starting location information of the data body b is read out from the recording medium for distribution α on the main storage section  426 , while the location information contained in the piece data d is read out from the auxiliary storage section  425  on the main storage section  426 , and the counting of a data length or a time from the relevant starting location information to the relevant location information is started (s 12 ). Thereafter, whether or not the counting is finished is determined (s 13 ). Thereby, the omitted part of the data body b is recognized. As a result of this determination, when it is determined that the counting has been finished and the omitted part of the data body b is recognized, if the bit length of the omitted data is smaller than the decryption bit length, the data body b is read out from the recording medium for distribution α and the omitted data contained in the piece data d is read out from the auxiliary storage section  425  on the main storage section  426  (namely, the data body b on the recording medium for distribution α and the omitted data on the auxiliary storage section  425  are transferred as the data of the decryption bit length) to be connected (s 14 ). Then, the data of the decryption bit length on the relevant main storage section  426  is decrypted by using the decryption key c 2  (s 15 ) and the relevant data is returned from the compressed state to the original state through the filter of the MPEG or the like (s 16 ), which reproduces the data body b (s 17 ). 
     If the bit length of the omitted data is larger than the decryption bit length, the data body b is read out from the recording medium for distribution α and part of the omitted data contained in the piece data d is read out from the auxiliary storage section  425  on the main storage section  426  (namely, the data body b on the recording medium for distribution α and part of the omitted data on the auxiliary storage section  425  are transferred as the data of the decryption bit length) to be connected, and subsequently the remaining omitted data contained in the piece data d (data of the decryption bit length) is read out from the auxiliary storage section  425  on the main storage section  426  (s 14 ). Then, the data on the main storage section  426  is decrypted by the decryption bit length by using the decryption key c 2  (s 15 ) and the relevant data is returned from the compressed state to the original state through the filter of the MPEG or the like (s 16 ), which reproduces the data body b (s 17 ). 
     Alternatively, part of the omitted data (data of the decryption bit length) contained in the piece data d is read out from the auxiliary storage section  425  on the main storage section  426 , and subsequently, the data body b is read out from the recording medium for distribution α and the remaining omitted data contained in the piece data d is read out from the auxiliary storage section  425  on the main storage section  426  to be connected (s 14 ). Then, the data on the main storage section  426  is decrypted by the decryption bit length by using the decryption key c 2  (s 15 ), and the relevant data is returned from the compressed state to the original state through the filter of MPEG or the like (s 16 ), which reproduces the data body b (s 17 ). In this manner, after the vicinity of the omitted part of the data body b is reproduced, again, the data body b on the recording medium for distribution α is read out on the main storage section  426 , and is sequentially decrypted by the decryption bit length by using the decryption key c 2 , and the relevant data is sequentially returned from the compressed state to the original state through the filter of MPEG or the like, which reproduces the subsequent data body b (s 18 ). In the case where the bit length of the omitted data is more than or equal to twice as large as the decryption bits, the processing at step  14  is performed continuously. This reproduction software program is finished upon end processing by the user. 
     Furthermore, the reproduction software, in addition to the above-described basic function, contains contents which are resident in the digital contents reproducing device  420  to manage the piece data d when the digital contents reproducing device  420  is turned ON. In this contents, the piece data d on the auxiliary memory section  425  is managed, while a difference between a piece data transmission data and time and a current date and time is obtained as an elapsed period from a time point when the piece data d is transmitted, and when this reaches the rental period contained in the rental information, it is determined to be outside of the rental period, and the piece data d and the decryption keys c 1 , c 2  on the auxiliary storage section  425  are deleted, and the predetermined flag is hauled down. 
     If the decryption key c 2  is stolen and an attempt to illegally reproduce the data body b of the contents file on the recording medium for distribution α by using the computer (including the digital contents reproducing device  420 ) without obtaining the piece data d is made, the computer is made to perform the same processing of the reproduction software as that at step  11  to thereby reproduce the data body b of the contents file on the recording medium for distribution α. At this time, when the data read out on the main storage section of the computer by the decryption bit length is data located before the omitted part, the stolen decryption key c 2  which has been in advance recorded on an auxiliary storage section of another computer is read out on the main storage section, and the data on the main storage section is decrypted (namely, is subjected to a predetermined calculation) by the decryption bit length by using the decryption key c 2 . Then, since it is decrypted by using the stolen decryption key c 2 , the data on the main storage section can be sequentially converted into a data row before encryption by the decryption bit length. Consequently, after that, the data is returned from the compressed state to the original state through the filter of MPEG or the like, which can reproduce the data body b. 
     However, when the data read out on the main storage section of the computer is data located after the omitted part, the decryption key c 2  stolen from the auxiliary storage section of another computer is read out on the main storage section, the relevant data on the main storage section is decrypted (namely, is subjected to the predetermined calculation) by the decryption bit length by using the decryption key c 2 . At this time, since the data row of the data on the main storage section is different from the data row after encryption (that is, the data row before omission) as shown in  FIG. 15 , it is converted into an unknown sequence of numbers or alphanumerics. When such unknown sequence of numbers or alphanumerics is passed through the filter of the MPEG or the like, the returning processing of the computer stops. This makes it impossible to reproduce the data of the data body b after the omitted part. 
     In the digital contents illegal use preventing system  400  as described above, the same effects as that of the illegal use preventing system  100  can be obtained. 
     In addition, in the digital contents illegal use preventing system  400 , after the data body b of the contents file is compressed and encrypted, part of the relevant data body b is omitted and the data body b is recorded on the recording medium for distribution α with this omitted part closed so as to continue the data body b. Therefore, even if the decryption key c 2  is stolen and thereby, the data body b is illegally reproduced by a computer or the like, when the data after omission of the data body b of the contents file on the recording medium for distribution α is read out on the main storage section of the computer by the decryption bit length and the relevant data is decrypted by the decryption bit length, the data is converted into unknown sequence of numbers or alphanumerics. When this unknown sequence of numbers or alphanumerics is passed through the filter of MPEG or the like, the returning processing stops, so that the data after the omitted part cannot be reproduced. Thus, in processing a large amount of data with equipment such as a computer, the data is read out on the main storage section of the equipment by the decryption bit length, and by making good use of the characteristic of the relevant equipment which decrypts and processes the data by the decryption bit length, the illegal reproduction of the data body b can be prevented. In addition, the data body b is recorded with the omitted part closed so as to continue the data body b. Namely, since the data body b as described above is digital data and consists of only a continuous alphanumeric sequence, when the omitted part is closed so as to continue the data body b, the location of the relevant omitted part cannot be specified. Therefore, it is also difficult to specify the location of the relevant omitted part and reproduce the data before the omitted part. Furthermore, if part of the data body b is omitted before encryption and the relevant omitted part is filled with dummy data or remains omitted, in the case where the data body b is compressed by using MPEG, the data body b other than the omitted part can be reproduced with the stolen decryption key c 2 . However, when part of the data body b is omitted after encryption and the omitted part is closed so as to continue the data body b, it becomes impossible to reproduce the data after the omitted part, which is very advantageous in preventing the illegal use of the data body b. 
     As to the recording medium for distributions α in the digital contents illegal use preventing system  400 , although the data body b is compressed and encrypted, and part of the relevant data body b is omitted and the data body b is recorded with the relevant omitted part closed so as to continue the data body b, whether or not the compression is performed is arbitrary. However, in the case where the compression is not performed, the data body b after the omitted part is reproduced as only an unknown continuous sequence of numbers or alphanumerics. Although MPEG is exemplified as the compressing method, naturally, another form can be used. Furthermore, although the contents file is structured so as to have the head information a and the data body b, it is obviously possible to record it with other information added thereto. This other information includes a program by which it is determined whether or not the reproduction software has been installed in the computer of the user, and when it is determined that the software has not been installed, HP of the management center  410  is automatically accessed, and the like. When this program has been recorded and the user sets the recording medium for distribution α which he or she has in advance obtained in his or her computer (computer equivalent to the digital contents reproducing device  420 , which is in a state that the reproduction software is not downloaded), the WEB address of the management center  410  is read out, and based on this, the management center  410  is automatically accessed. Thereafter, the reproduction software can be obtained by the above-described procedure. 
     While the location information is designed to be a data length or a time from the starting location information to the omitted part, it may be an address value indicating the omitted part or the like. In this case, it is sequentially determined whether or not an address value of the data body b on recording medium for distribution α to be read out next and the location information coincide with each other, and as a result of the determination, when they are determined not to coincide with each other, the data body b on the recording medium for distribution α which the address value indicates is read out, while when they are determined to coincide with each other, the omitted data on the memory section  425  is read out. 
     While the piece data d consists of the omitted data body and the location information, whether or not the location information is contained is arbitrary. In this case, for example, omitted location information indicating the omitted part is in advance recorded before the omitted part of the data body b, and the data body b is reproduced, and further counting is performed from the starting location information to the omitted location information. When this counting is finished, the omitted data on the auxiliary storage section  425  may be reproduced as the data of the relevant omitted part. Alternatively, a location of the omitted part of the data body b is predetermined, and the location information of the omitted data is prepared in the reproduction software. It is possible that the data body b is reproduced and at the same time, the omitted part of the data body b is recognized based on this location information and the omitted data on the memory section  425  is reproduced as the data of the relevant omitted part. 
     The interruption program for user registration, the interruption program for reproduction software download and the interruption program for piece data delivery are only one example, and can be changed in design according to need. 
     Furthermore, in the case where the contents file is recorded on the auxiliary storage section  425  of the digital contents reproducing device  420 , after the rental period has passed, the contents file may be deleted together with the piece data d, or separately from the piece data d, an elapsed time from a point of time when the contents file is received is obtained and when the relevant elapsed time reaches a predetermined period, the relevant contents file may be deleted. 
     In the fourth embodiment, the system can also be changed in design so as to prevent illegal use of a contents file on the recording medium for distribution α not delivered on a rental basis but transferred to the user for pay or for free. In this case, advantages similar to the foregoing are also brought about. In the contents of the reproduction software used in this case, only the series of the processings when the delivered contents file is inside and outside of the rental period are deleted. With respect to the digital contents reproducing device, the reproduction software may not be downloaded from the management center  410 , but may be installed through a recording medium such as CD. Furthermore, obviously, the digital contents reproducing device is not a computer but can be a dedicated device, and any configuration can be used as long as the digital contents reproducing device has the function in which when a reproduction application for a contents file under the condition of authentication and billing is inputted by a user, the relevant application is transmitted to the management center  410  via the communication line β and thereafter when the piece data d is transmitted from the management center  410  via the communication line β, the data body b on the recording medium for distribution α is reproduced by using the header information on the recording medium for distribution α and the relevant piece data d at the time of reproducing operation. 
     Embodiment 5 
     Next, a fifth embodiment of the present invention is described with reference to the drawings.  FIG. 17  is a configuration diagram of a digital contents illegal use preventing system relating to the fifth embodiment of the present invention, and  FIG. 18  is a flowchart of reproduction software used for this system. 
     A digital contents illegal use preventing system  500  as shown in  FIG. 17  has the same configuration as that of the illegal use preventing system  200 . Different points are the configuration of the contents file and the contents of reproducing software recording on an auxiliary storage section  525  of a digital contents reproducing device  520  (refer to  FIG. 18 ). Hereinafter, the different points are described in detail, and a description of overlapping parts is omitted. 
     In the contents file, similar to Embodiment 4, the header information a is recorded on a recording medium in a state that reproduction information contained in the relevant header information a is encrypted, while the data body b is compressed in a compressing method such as MPEG and is encrypted, and part of the relevant data body b is omitted, the relevant omitted part is closed so as to continue the data body b, and is recorded on a newly provided data body memory section (not shown) in a state that dummy data of the same bit length as the omitted part is added to the end thereof. Thereafter, the data body b on the data body memory section of the device for creating a recording medium for distribution  140  is transferred to a delivery management center  510  via the communication line β and is recorded on a digital contents DB  511  (auxiliary storage device) of the delivery management center  510  (electronic equipment). The data body b may be recorded on a recording medium and be sent to the delivery management center  510  by mail to be read and thereby recorded on the digital contents DB  511 . 
     The digital contents reproducing device  520  is a general-purpose computer used by a user. In the figure, reference numeral  521  denotes a control section such as CPU, reference numeral  522  denotes an output section such as a monitor and a speaker, reference numeral  523  denotes an operation section such as a keyboard and a mouse, reference numeral  524  denotes a reproduction and copy section reading/writing the data with respect to the recording medium and the like, reference numeral  525  denotes an auxiliary storage section such as a hard disk, reference numeral  526  denotes a communication section for performing communication which is connected to the communication line β, and reference numeral  527  denotes a main storage section such as DRAM. 
     On the auxiliary storage section  525 , in addition to basic programs such as an operation system as a computer, the reproduction software as shown in  FIG. 18  is recorded. The contents of the reproduction software will be described later. The processing of the relevant reproduction software on the main storage section  527  by the control section  521  allows a function to be exerted as the digital contents reproducing device  520  in which the data body b recorded on the auxiliary storage section  525  or the recording medium is sequentially transferred to the main storage section  527  by the decryption bit length, the relevant data on the main storage section  527  is sequentially decrypted by the decryption bit length (that is, decrypted by the decryption bit length), and the relevant data is returned from a compressed state to an original state for reproduction (reading). 
     A description of a digital contents illegal use preventing method using the digital contents reproducing device  520  of the digital contents illegal use preventing system  500  configured as described above is given, and in conjunction of this, the operation of the delivery management center  510 , the operation of the digital contents reproducing device  520 , and the contents of respective programs are described. The decryption keys c 1 , c 2  are recorded on a piece data DB  516  of the delivery management center  510 . Hereinafter, for convenience, a case where one point of the data body b is omitted is described. 
     In the digital contents reproducing device  520 , the reproduction software is downloaded by the same procedure as that of Embodiment 2 and is recorded on the auxiliary storage section  525 . Then, by the same procedure as that of Embodiment 2, the contents file is downloaded from the digital contents DB  511  of the delivery management center  510  and is recorded on the auxiliary storage section  525  of the digital contents reproducing device  520  or on the recording medium. 
     Thereafter, when the reproduction software is executed by the user (in the case where the contents file is recorded on the recording medium, the reproduction software is executed and meanwhile, the relevant recording medium is set in a reproduction and copy section  524 ), this digital contents reproducing device  520  outputs and displays the data such as a reproduction player and a play list contained in the relevant reproduction software on the output section  522 . Then, the play list is displayed on a screen of the relevant reproducing player (s 1 ). On this play list, together with a file name of the downloaded contents file, whether or not the relevant contents file is being rented is indicated. Namely, the contents file having a predetermined flag hoisted, which indicates that a reproduction application has been made, is displayed. Then, based on this play list, whether or not reproducing operation has been performed for the contents file being rented is determined through the operation section  523  (s 2 ). 
     If it is determined that the reproducing operation has not been performed, then it is determined whether or not reproduction application operation of the contents file not being rented which is displayed on the play list has been performed through the operation section  523  (s 3 ). As a result, if the reproduction application operation has not been performed, then it is determined whether or not reading operation (operation of DISC LOAD) of the recording medium has been performed through the operation section  523  (s 4 ). When the operation of DISC LOAD is performed, a contents list showing a contents file on the recording medium which is not recorded on the play list (that is, downloaded on the recording medium with another computer or the like) is outputted and displayed on the output section  522  (s 5 ). Namely, contents information contained in the header information a of the contents file with a predetermined flag not hoisted among the contents files on the recording medium is read out on the main storage section  527  and is displayed on the contents list. 
     Thereafter, when an application for reproduction of the contents file not being rented on the play list or the contents file on the contents list is performed by the user (s 3  or s 6 ), the contents information contained in the header information a of the relevant contents file on the auxiliary storage section  525  or the recording medium is read out on the main storage section  527 . Then, based on a WEB address contained in the relevant contents information, a contents ID contained in the relevant contents information is transmitted to the delivery management center  510  via the communication line β. In this manner, the execution of the reproduction application is transmitted. 
     The management center  510  processes the interruption program for piece data delivery (refer to  FIG. 9 ). Then, the data necessary for the reproduction application processing is read out from the memory section  516  and is transmitted to the digital contents reproducing device  520  via the communication line β (s 31 ). Based on this data, the digital contents reproducing device  520  reads out the data of a reproduction application screen on the main storage section  426  to output and display it on the output section  522  (s 7 ). 
     Thereafter, when the user sequentially inputs or selects a rental period through the operation section  523  as displayed on the reproduction application screen (this determines a rental amount of money), and finally inputs a user ID and a password through the operation section  523  as a reproduction application of the contents file (s 8 ), the digital contents reproducing device  520  shifts the display output to an authentication screen, and meanwhile, transmits the inputted application data to the delivery management center  510  via the communication line β. At this time, the contents ID of the contents information on the auxiliary storage section  525  or on the recording medium and the player ID on the relevant auxiliary storage section  525  are read out and transmitted to the delivery management center  510  together with the application data (s 9 ). 
     Upon receiving the relevant application data or the like, the delivery management center  510  confirms the authentication of the user relating to the relevant application (s 32 ). Namely, with reference to the received user ID and player ID of the user, etc., the user information of the relevant user is read out from a user information DB  514 , and whether or not the relevant user is an authentic user is confirmed. At this time, the delivery management center  510  has in advance prepared a list of inappropriate persons with nonpayments of rental fee more than or equal to predetermined times or the like in the user information DB  514 , and in addition to the authentication, confirms whether or not the user falls under the list of inappropriate persons (this confirmation of the list of inappropriate persons is arbitrary). 
     In the case where the delivery management center  510  has confirmed that the user relating to the application is an unauthentic user or an authentic user but a person who falls under the list of inappropriate persons, the rejection of the application of the user is rejected is transmitted to the digital contents reproducing device  520  via the communication line β (s 33 ). Then, the interruption program for piece data delivery is finished. 
     On the other hand, in the case where it has been confirmed that the user relating to the application is an authentic user and a person who does not fall under the list of inappropriate persons, with reference to the player ID of the user or the like, accounting is recorded on the user information of the user on the user information DB  514 , while with reference to the contents ID, the piece data DB  516  is searched to read out the piece data d and the decryption keys c 1 , c 2  corresponding to the relevant contents ID and to transmit them to the digital contents reproducing device  520  as a reply indicating that the application of the user is accepted together with the rental information indicating the rental period and the like which are contained in the application data via the communication line β (s 34 ). Then, the processing of the interrupt program for piece data delivery is finished. 
     The accounting is charged to a bank/credit card company  530  or charged directly to the user, based on the user information DB  514  for every predetermined period and the user transfers the charge to an account or pays it in a convenience store or the like. Furthermore, in the case where the delivery management center  510  is connected to the bank/credit card company  530  via the communication line β, it is obviously possible to immediately settle accounts, too. 
     Thereafter, when the digital contents reproducing device  520  receives the rejection of the application of the user via the communication line β (s 10 ), it outputs and displays data of an error message contained in the data of the rejection on the output section  522  (s 11 ). 
     On the other hand, when the piece data d, decryption keys c 1 , c 2  and the rental information are received via the communication line β (s 10 ), the predetermined flag is hoisted, while the piece data d, the decryption keys c 1 , c 2  and the rental information are recorded on the auxiliary storage section  525  (s 12 ). At the same time, by using a clock function of the computer, a piece data transmission date and time is recorded on the auxiliary storage section  525 . Then, the play list is updated and is outputted and displayed on the output section  522 , which allows a file name of the contents file with the piece data d obtained to be displayed on the relevant play list (s 1 ). 
     Thereafter, when the reproducing operation of the contents file being rented is performed based on the play list through the operation section  523  (s 2 ), the digital contents reproducing device  520  reads out on the main storage section  527  the reproduction information contained in the header information a of the contents file on the auxiliary storage section  525  or on the recording medium, while it reads out the decryption key c 1  from the auxiliary storage section  525  on the main storage section  527 . Then, by using the relevant reproduction information, the data body b on the auxiliary storage section  525  or on the recording medium is sequentially read out by the decryption bit length on the main storage section  527  and meanwhile, the decryption key c 2  is read out from the auxiliary storage section  525  on the main storage section  527 . In addition, the relevant data on the main storage section  527  is decrypted by the decryption bit length by using the decryption key c 2 , and is returned from the compressed state to the original state through a filter of MPEG or the like, which reproduces the data body b (s 13 ). 
     Therewith, the starting location information of the data body b on the auxiliary storage section  525  or the recording medium is read out on the main storage section  527 , while the starting location information contained in the piece data d on the auxiliary storage section  525  is read out on the main storage section  527 , and the counting of a data length or a time from the starting location information to the location information is started (s 14 ). Thereafter, whether or not the counting is finished is determined (s 15 ). Thereby, the omitted part of the data body b is recognized. As a result of this determination, when it is determined that the counting has been finished and the omitted part of the data body b is recognized, if the bit length of the omitted data is smaller than the decryption bit length, the data body b is read out from the auxiliary storage section  525  or the recording medium and the omitted data contained in the piece data d is read out from the auxiliary storage section  525  on the main storage section  527  (namely, the data body b on the recording medium or the auxiliary storage section  525  and the omitted data on the auxiliary storage section  525  are transferred as the data of the decryption bit length) to be connected (s 16 ). Then, the data of the decryption bit length on the main storage section  527  is decrypted by using the decryption key c 2  (s 17 ) and the relevant data is returned from the compressed state to the original state through the filter of the MPEG or the like (s 18 ), which reproduces the data body b (s 19 ). 
     If the bit length of the omitted data is larger than the decryption bit length, the data body b is read out from the auxiliary storage section  525  or the recording medium and part of the omitted data contained in the piece data d is read out from the auxiliary storage section  525  on the main storage section  527  (namely, the data body b on the recording medium for distribution α and part of the omitted data on the auxiliary storage section  525  are transferred as the data of the decryption bit length) to be connected, and subsequently the remaining omitted data contained in the piece data d (data of the decryption bit length) is read out from the auxiliary storage section  525  on the main storage section  527  (s 16 ). Then, the data on the main storage section  527  is decrypted by the decryption bit length by using the decryption key c 2  (s 17 ) and the relevant data is returned from the compressed state to the original state through the filter of the MPEG or the like (s 18 ), which reproduces the data body b (s 19 ). 
     Alternatively, part of the omitted data (data of the decryption bit length) contained in the piece data d is read out from the auxiliary storage section  525  on the main storage section  527 , and subsequently, the data body b is read out from the auxiliary storage section  525  or the recording medium and the remaining omitted data contained in the piece data d is read out from the auxiliary storage section  525  on the main storage section  527  to be connected (s 16 ). Then, the data on the main storage section  527  is decrypted by the decryption bit length by using the decryption key c 2  (s 17 ), and the relevant data is returned from the compressed state to the original state through the filter of MPEG or the like (s 18 ), which reproduces the data body b (s 19 ). In this manner, after the vicinity of the omitted part of the data body b is reproduced, again, the data body b on the auxiliary storage section  525  or the recording medium is read out on the main storage section  527 , and is sequentially decrypted by the decryption bit length by using the decryption key c 2 , and the relevant data is sequentially returned from the compressed state to the original state through the filter of MPEG or the like, which reproduces the subsequent data body b (s 20 ). In the case where the bit length of the omitted data is more than or equal to twice as large as the decryption bits, the processing at step  16  is performed continuously. This reproduction software program is finished upon end processing by the user. 
     Furthermore, in addition to the above-described basic function, to the reproduction software, there are added contents which are resident in the digital contents reproducing device  520  to manage the piece data d when the digital contents reproducing device  520  is turned ON. In this contents, the piece data d on the auxiliary storage section  525  is managed, while a difference between a piece data transmission data and time and a current date and time is obtained as an elapsed period from a time point when the piece data d is transmitted, and when this reaches the rental period contained in the rental information, it is determined to be outside of the rental period, and the piece data d and the decryption keys c 1 , c 2  on the auxiliary storage section  525  are deleted, while the predetermined flag is hauled down. 
     If the decryption key c 2  is stolen and an attempt to illegally reproduce the data body b of the contents file recorded on the auxiliary storage section of the relevant computer or the recording medium by using the computer (including the digital contents reproducing device  520 ) without obtaining the piece data d is made, the computer is made to perform the same processing of the reproduction software as that at step  13  to thereby reproduce the data body b of the contents file on the auxiliary storage section or on the recording medium. At this time, when the data read out on the main storage section of the computer by the decryption bit length is data located before the omitted part, the stolen decryption key c 2  which has been in advance recorded on an auxiliary storage section of another computer is read out on the main storage section, and the data on the main storage section is decrypted (namely, is subjected to a predetermined calculation) by the decryption bit length by using the decryption key c 2 . Then, since it is decrypted by using decryption key c 2 , the data can be converted into a data row before encryption. Consequently, after that, the data is returned from the compressed state to the original state through the filter of MPEG or the like, which can reproduce the data body b. 
     However, when the data read out on the main storage section of the computer by the decryption bit length is data located after the omitted part, the decryption key c 2  stolen from the auxiliary storage section of another computer is read out on the main storage section, the relevant data on the main storage section is decrypted (namely, is subjected to the predetermined calculation) by the decryption bit length by using the decryption key c 2 . At this time, since the data row of the data on the main storage section is different from the data row after encryption (that is, the data row before omission) (take over and refer to  FIG. 15 ), it is converted into an unknown sequence of numbers or alphanumerics. When these unknown sequence of numbers or alphanumerics is passed through the filter of the MPEG or the like, the returning processing of the above-mentioned another computer stops. This makes it impossible to reproduce the data of the data body b after the omitted part. 
     In the digital contents illegal use preventing system  500  as described above, the same effects as that of the illegal use preventing system  200  can be obtained. 
     In addition, in the digital contents illegal use preventing system  500 , after the data body b of the contents file is compressed and decrypted, part of the relevant data body b is omitted and the data body b is recorded on the auxiliary storage section or on the recording medium with this omitted part closed so as to continue the data body b. Therefore, even if the decryption key c 2  is stolen and thereby, the data body b is illegally reproduced by a computer or the like, when the data after omission of the data body b of the contents file on the auxiliary storage section or on the recording medium is read out on the main storage section of the computer by the decryption bit length and is decrypted by the decryption bit length, the data is converted into unknown sequence of numbers or alphanumerics. When this unknown sequence of numbers or alphanumerics is passed through the filter of MPEG or the like, the returning processing stops, so that the data after the omitted part cannot be reproduced. Thus, in processing a large amount of data with equipment such as a computer, by making good use of the characteristic of the relevant equipment in which the data is read out on the main storage section of the equipment by the decryption bit length to be processed, the illegal reproduction of the data body b can be prevented. In addition, the data body b is recorded with the omitted part closed so as to continue the data body b. Namely, since the data body b as described above is digital data and consists of only a continuous alphanumeric sequence, when the omitted part is closed so as to continue the data body b, the location of the relevant omitted part cannot be specified. Therefore, it is also difficult to specify the location of the omitted part and reproduce the data before the omitted part. Furthermore, if part of the data body b is omitted before encryption and the omitted part is filled with dummy data or remains omitted, in the case where the data body b is compressed by using MPEG, the data body b other than the omitted part can be reproduced with the stolen decryption key c 2 . However, when part of the data body b is omitted after encryption and the omitted part is closed so as to continue the data body b, it becomes impossible to reproduce the data after omitted part, which is very advantageous in preventing the illegal use of the data body b. 
     Although the data body b is compressed and encrypted in the digital contents DB  511 , and part of the relevant data body b is omitted and the data body b is recorded with the relevant omitted part closed so as to continue the data body, whether or not the compression is performed is arbitrary. However, in the case where the compression is not performed, the data body b after the omitted part is reproduced as only an unknown continuous sequence of numbers or alphanumerics. Although MPEG is exemplified as the compressing method, naturally, another form can be used. Furthermore, although the contents file is structured so as to have the head information a and the data body b, it is obviously possible to record it with other information added thereto. This other information includes a program by which it is determined whether or not the reproduction software has been installed in the computer of the user, and when it is determined that the software has not been installed, HP of the delivery management center  510  is automatically accessed, and the like. When this program has been recorded and the user attempts to execute the contents file which he or she has in advance obtained in his or her computer (computer equivalent to the digital contents reproducing device  520 , which is in a state that the reproduction software is not downloaded), the WEB address of the delivery management center  510  is read out, and based on this, the management center  510  is automatically accessed. Thereafter, the reproduction software can be obtained by the above-described procedure. 
     While the location information is designed to be a data length or a time from the starting location information to the omitted part, it may be an address value indicating the omitted part or the like. In this case, it is sequentially determined whether or not an address value of the data body b on recording medium for distribution α to be read out next and the location information coincide with each other, and as a result of the determination, when they are determined not to coincide with each other, the data body b on the auxiliary storage section or on the recording medium which the address value indicates is read out, while when they are determined to coincide with each other, the omitted data on the auxiliary storage section  525  is read out. 
     While the piece data d consists of the omitted data body and the location information, whether or not the location information is contained is arbitrary. In this case, for example, omitted location information indicating the omitted part is in advance recorded before the omitted part of the data body b, and the data body b is reproduced, and further counting is performed from the starting location information to the omitted location information. When this counting is finished, the omitted data on the auxiliary storage section  525  may be reproduced as the data of the relevant omitted part. Alternatively, a location of the omitted part of the data body b is predetermined, and the location information of the omitted data is prepared in the reproduction software. It is possible that the data body b is reproduced and at the same time, the omitted part of the data body b is recognized based on this location information and the omitted data on the auxiliary storage section  525  is reproduced as the data of the relevant omitted part. 
     The interruption program for user registration, the interruption program for reproduction software download and the interruption program for pieced at a delivery are only one example, and can be changed in design according to need. 
     It goes without saying that this data illegal use preventing method and the programs can be applied to the digital contents reproducing device  320  of Embodiment 3. 
     Furthermore, in the case where the contents file is recorded on the auxiliary storage section  525  of the digital contents reproducing device  520 , after the rental period has passed, the contents file may be deleted together with the piece data d, or separately from the piece data d, an elapsed time from a point of time when the contents file is received is obtained and when the relevant elapsed time reaches a predetermined period, the relevant contents file may be deleted. 
     In the fifth embodiment, the system can also be changed in design so as to prevent illegal use of a contents file not delivered on a rental basis but transferred for pay or for free. In this case, advantages similar to the foregoing are also brought about. In the contents of the reproduction software used in this case, only the processing when the delivered contents file is outside of the rental period is deleted. With respect to the digital contents reproducing device  520 , the reproduction software may not be downloaded from the delivery management center  510 , but may be installed through a recording medium such as CD. Furthermore, obviously, the digital contents reproducing device is not a computer but can be a dedicated device. 
     In the above-described embodiments, although the method for processing the data body b of the digital contents is described, in the processing method of the data which is encrypted and decrypted by the decryption bit length, thereby being read, any data can be processed as long as the data is encrypted, part of a bit length different from the decryption bit length of this data is omitted, and the omitted part is closed to continue the relevant data. With respect to the equipment for processing the data, any equipment may be used as long as it can realize a function similar to that of the device for creating a recording medium for distribution  140 . For example, the above-mentioned method can be used for a data reading device which is a computer to process the data. 
     Furthermore, this data processing method is available as a method for preventing the illegal use of transmitted and received data. In this case, a digital contents reproducing device only needs to be a data reading device which can read the data, a management center and a delivery management center only needs to be electronic equipment which is connected to the data reading device via a communication line, and has an auxiliary storage device recording the omitted data. The electronic equipment is a concept including a data reading device. Specifically, in transmitting the data recorded on the auxiliary storage section of the data reading device, the data is encrypted, at least part of the relevant data is omitted, and the relevant omitted part is closed to continue the data, and the relevant data is recorded on the auxiliary storage section of the data reading device, while the omitted data is recorded on the auxiliary storage section together with location information indicating in which part of the data the relevant omitted part is located. Thereafter, the data reading device is made to transmit the data on the auxiliary storage section to the electronic equipment, while the omitted data, the location information and a decryption key are transmitted to the above-mentioned other data reading device separately from the data. This enables the data to securely be transmitted to the other data reading device. If the data and the encryption key are stolen, reading is disabled unless the omitted data and the location information are obtained, which can prevent the illegal use of the data. It goes without saying that the omitted data and location information are desirably transmitted separately from the decryption key.