INFORMATION PROCESSING APPARATUS AND METHOD, AND APROGRAM CROSS REFERENCES TO RELATED APPLICATIONS The present invention contains subject matter related to Japanese Patent Application JP 2006-246148, filed in the Japan Patent Office on September 11, 2006, the entire contents of which being incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing apparatus and method, and a program therefor. In particular, the present invention relates to an information processing apparatus and method, and a program therefor which enable moving out and moving back of a part of a content with greatly simplified processing, 2. Description of the Related Art In recent years, contents such as video, audio, and the like are widely used, and use of recording/reproduction apparatuses capable of recording and reproducing these contents as digital data is also spreading. For example, use of recording apparatuses capable of storing broadcast contents as digital data in a digital versatile disc (DVD) or a hard disc drive (HDD) is rapidly spreading. In addition, digital terrestrial broadcasting has recently been started after digital broadcasting that employs a broadcasting satellite. In such digital broadcasting, high definition television (HDV) video, which has a higher resolution than video that is broadcast in traditional broadcasting, is broadcast, and development of a recording apparatus that is capable of recording such a broadcast content on an optical disk or the like while maintaining picture quality thereof is advancing. The term "content" refers to a variety of matters created by human creative activities. Examples of the contents include films, music, dramas, literature, photographs, comics, animation, computer games, other types of written, graphic, color-based, audio, motion-based, and video matters, a combination of the above, and a program for providing information related to the above via a computer. Note that, in the present specification, so-called content data, i.e., matters created by the human creative activities and converted by a device into a processible form, such as an electrical signal, or fixed on memory, for example, is also referred to as a content. As described above, at present, it is easy to store high-quality contents in portable storage media. Accordingly, importance of protection of copyright of the contents is increasing. As a method for protecting copyright of video contents, a method of adding copy control information (CCI), which represents whether or not copying of a video content is possible, to the video content is normally employed at present. For example, use of the copy control information enables the video content to enter a Copy Free state, in which copying is not restricted, a Copy Once state, in which copying is permitted only once, a Copy Never state, in which copying is prohibited, or the like. In the current digital broadcasting mentioned above, copy control information representing "Copy Once" is added to all contents, and the recording apparatus normally causes such a content to enter the Copy Never state before recording the content on a storage medium. A video content recorded on the storage medium after being caused to enter the Copy Never state is permitted to be copied to another storage medium on the condition that data of the video content be deleted from the storage medium. This operation of copying the data to the other storage medium while deleting the original data is called "Move". Thus, in the case where a video content has been received by the recording apparatus via digital broadcasting or the like and recorded on an HDD within the recording apparatus, for example, if a user desires to keep the video content for a long period of time, the user is able to move the video content to a removable medium such as a DVD. Thus, user convenience is improved while preventing unlawful production of copies in large quantities. In general, the content to be moved is encrypted in a source from a moving source. Thereafter, the content encrypted (hereinafter referred to as the encrypted content) is copied to a moving destination together with information (hereinafter referred to as identification information) for identifying the encrypted content, e.g., information composed of key information for decrypting the encrypted content, a protected content ID, and the like. Further, the encrypted content copied to the moving destination can be copied back to the moving source on the condition that the content be deleted from the moving destination. That is, a first moving, from the moving source to the moving destination, and a subsequent second moving, from the moving destination to the moving source, are possible. Hereinafter, the first moving and the second moving will be referred to as moving out and moving back, respectively. As known apparatuses enabling moving out and moving back, apparatuses disclosed in Japanese Patent Laid-open No. 2006-4543 (US 2005-0281540 Al)(referred to as Patent Document 1 hereinafter) and Japanese Patent Laid-open No. 2006-107165 (referred to as Patent Document 2 hereinafter)can be cited, for example. Known apparatuses, such as those disclosed in Patent Document 1 and Patent Document 2, have a problem in that in the case where an object to be moved is not the entire content but a part of the content, time-consuming processing may be required for both moving out and moving back. This problem will now be described below with reference to FIGS. 1 to 3. Referring to FIG. 1, it is assumed that, in a known moving source device 1, an encrypted content 11, which is a candidate for an object to be moved, and identification information 12 including key information A and a protected content ID are held in a single file. In this case, although not shown, in the case where the object to be moved is the entire encrypted content 11, the moving source device 1 copies the encrypted content 11 as it is and the identification information 12 to a moving destination device 2-A or 2-B, and deletes the encrypted content 11 (i.e., the original data) and so on within itself, thereby completing moving out. In contrast, in the case where the object to be moved is a part of the encrypted content 11 (hereinafter referred to as an encrypted part), specifically, in the case where, as illustrated in FIG. 2, an object to be moved to the moving destination device 2-A is an encrypted part 11-1 and an object to be moved to the moving destination device 2-B is an encrypted part 11-2, for example, moving out necessitates the following time-consuming series of processes. That is, since direct extraction of the encrypted parts 11-1 and 11-2 from the encrypted content 11 is difficult, the moving source device 1 decrypts the entire encrypted content 11 using the key information A. As a result, the encrypted content 11 is converted back to a non-encrypted content. The moving source device 1 extracts a non-encrypted part corresponding to the encrypted part 11-1 from the non-encrypted content, and re-encrypts the extracted non-encrypted part to generate an encrypted content 21-1. Thus, the new encrypted content 21-1 corresponding to the encrypted part 11-1 is generated. At the time of this re-encryption, an encryption key different from an encryption key used for the encrypted content 11 is used. Accordingly, the moving source device 1 generates key information B necessary for decrypting the encrypted content 21-1, i.e., key information B different from the key information A, and also generates a protected content ID for the encrypted content 21-1, thereby generating identification information 22 containing them. Thus, the new identification information 22 different from the identification information 12 is generated for the new encrypted content 21-1. Then, the moving source device 1 copies the encrypted content 21-1 and the identification information 22 to the moving destination device 2-A. Similarly, the moving source device 1 extracts a non-encrypted part corresponding to the encrypted part 11-2 from the non-encrypted content, and re-encrypts the extracted non-encrypted part to generate an encrypted content 21-2. Thus, the new encrypted content 21-2 corresponding to the encrypted part 11-2 is generated. At the time of this re-encryption, an encryption key different from the encryption keys used for the encrypted content 11 and the encrypted content 21-1 is used. Accordingly, the moving source device 1 generates key information C necessary for decrypting the encrypted content 21-2, i.e., key information C different from the key information A or B, and also generates a protected content ID for the encrypted content 21-2, thereby generating identification information 23 containing them. Thus, the new identification information 23 different from the identification information 12 or 22 is generated for the new encrypted content 21-2. Then, the moving source device 1 copies the encrypted content 21-2 and the identification information 23 to the moving destination device 2-B. As described above, in order to copy the encrypted part 11-1 (actually, the encrypted content 21-1) and the encrypted part 11-2 (actually, the encrypted content 21-2) to the moving destination device 2-A and the moving destination device 2-B, respectively, the time-consuming series of processes, i.e., the decryption of the encrypted content 11, the re-encryption for generating the new encrypted contents 21-1 and 21-2, and generation of the new identification information 22 and 23, may be required. In addition, in order to complete the moving out, deletion of the original data in the moving source device 1, i.e., deletion of the encrypted parts 11-1 and 11-2, may be required. This deletion necessitates the following time-consuming processes. That is, the moving source device 1 deletes the new encrypted contents 21-1 and 21-2. In addition, the moving source device 1 re-encrypts a non-encrypted part that is not the object of moving among the non-encrypted content using the encryption key corresponding to the key information A to generate an encrypted part 11-3, and holds the generated encrypted part 11-3 in the original file so as to be associated with the identification information 12. As a result of the above series of processes, a process equivalent to the deletion of the encrypted parts 11-1 and 11-2 is completed. The moving out of the encrypted part 11-1 to the moving destination device 2-A and the moving out of the encrypted part 11-2 to the moving destination device 2-B are completed after the above time-consuming series of processes are performed. As illustrated in FIG. 3, when moving back of the encrypted content 21-1 from the moving destination device 2-A to the moving source device 1 has been performed, the encrypted content 21-1 is held, in the moving source device 1, in a file different from the file of the original encrypted content 11, i.e., the file in which the encrypted part 11-3 is stored at the time of the moving back. Similarly, when moving back of the encrypted content 21-2 from the moving destination device 2-B to the moving source device 1 has been performed, the encrypted content 21-2 is held, in the moving source device 1, in a file different from the file of the original encrypted content 11, i.e., the file in which the encrypted part 11-3 is stored at the time of the moving back. However, completion of the moving back from the moving destination devices 2-A and 2-B to the moving source device 1 means that a state as illustrated in FIG. 1 is achieved again; that is, reconstruction of the encrypted content 11 and storage thereof in the original file is necessary. The reconstruction of the encrypted content 11 necessitates the following time-consuming processes. That is, the moving source device 1 decrypts the encrypted part 11-3 using the key information A. The moving source device 1 also decrypts the encrypted content 21-1 corresponding to the encrypted part 11-1 using the key information B. The moving source device 1 also decrypts the encrypted content 21-2 corresponding to the encrypted part 11-2 using the key information C. Next, the moving source device 1 combines the three non-encrypted parts obtained by the above three decryption processes to generate a non-encrypted content. Next, the moving source device 1 re-encrypts the generated non-encrypted content using the encryption key corresponding to the key information A to reconstruct the encrypted content 11. Then, the moving source device 1 holds the reconstructed encrypted content 11 in the original file so as to be associated with the identification information 12. After the above time-consuming series of processes are performed, the state illustrated in FIG. 1 is achieved again, and the moving back from the moving destination devices 2-A and 2-B to the moving source device 1 is completed. SUMMARY OF THE INVENTION The present invention enables moving out and moving back of a part of a content with greatly simplified processing. According to one embodiment of the present invention, there is provided an information processing apparatus that processes an encrypted content and which includes a control section configured to control the following processes to be performed independently in a specified order as a process for achieving moving out of at least a part of the encrypted content from a moving source to a moving destination: a generation process of generating the encrypted content composed of a plurality of encrypted content units to which different serial numbers are assigned, and generating, as identification information, data necessary for identifying and making reproducible the encrypted content; a moving range determination process of determining, within the encrypted content generated by the generation process, a moving object range composed of one or more of the encrypted content units; a holding process of holding, as content information, a pair of serial number information representing serial numbers assigned to the one or more of the encrypted content units contained in the moving object range determined by the moving range determination process and the identification information generated by the generation process in the moving source; a copying process of copying a part of the encrypted content generated by the generation process that corresponds to the moving object range determined by the moving range determination process to the moving destination together with the identification information generated by the generation process; and an inactivation process of causing at least the part of the encrypted content generated by the generation process that corresponds to the moving object range determined by the moving range determination process to enter an inactive state in the moving source. As control of the inactivation process, the control section may control only the part of the encrypted content generated by the generation process that corresponds to the moving object range determined by the moving range determination process to enter the inactive state in the moving source. The control section may further control the following processes to be performed independently in a specified order as a process for achieving moving back from the moving destination to the moving source: a collation process of collating the content information held in the moving source by the holding process with information obtained from the encrypted content and the identification information in the moving destination; a deletion process of deleting the encrypted content and the identification information from the moving destination after the collation is successfully completed by the collation process; and an activation process of, after the collation is successfully completed by the collation process, causing a part of the encrypted content generated by the generation process that corresponds to the encrypted content in the moving destination to enter an active state in the moving source, As control of the inactivation process, the control section may control the entire encrypted content generated by the generation process to enter the inactive state in the moving source. The control section may further control the following processes to be performed independently in a specified order as a process for achieving moving back from the moving destination to the moving source: a collation process of collating the content information held in the moving source by the holding process with information obtained from the encrypted content and the identification information in the moving destination; a deletion process of deleting the encrypted content and the identification information from the moving destination after the collation is successfully completed by the collation process; and an activation process of, after the collation is successfully completed by the collation process, causing the entire encrypted content generated by the generation process to enter the active state in the moving source if moving back of the encrypted content in the moving destination results in completion of moving back of the entire encrypted content generated by the generation process, but otherwise returning a right of reproducing the part of the encrypted content generated by the generation process that corresponds to the encrypted content in the moving destination. The inactive state may be an irreproducible state. According to one embodiment of the present invention, there is provided an information processing method employed by an information processing apparatus that processes an encrypted content, for achieving moving out of at least a part of the encrypted content from a moving source to a moving destination, the method including the steps of: generating the encrypted content composed of a plurality of encrypted content units to which different serial numbers are assigned, and generating, as identification information, data necessary for identifying and making reproducible the encrypted content; determining, within the encrypted content generated in the generating step, a moving object range composed of one or more of the encrypted content units; holding, as content information, a pair of serial number information representing serial numbers assigned to the one or more of the encrypted content units contained in the moving object range determined in the determining and the identification information generated in the generating step in the moving source; copying a part of the encrypted content generated in the generating step that corresponds to the moving object range determined in the determining step to the moving destination together with the identification information generated in the generating step; and causing at least the part of the encrypted content generated in the generating step that corresponds to the moving object range determined in the determining step to enter an inactive state in the moving source, wherein the information processing apparatus executes processes of the above steps for achieving the moving out independently in a specified order. According to one embodiment of the present invention, there is provided a program corresponding to the above information processing method according to one embodiment of the present invention. In the information processing apparatus and method, and the program according to one embodiment of the present invention, the following processes are performed independently in a specified order as a move-out process for achieving moving out of at least a part of an encrypted content from a moving source to a moving destination: a generation process of generating the encrypted content composed of a plurality of encrypted content units to which different serial numbers are assigned, and generating, as identification information, data necessary for identifying and making reproducible the encrypted content; a moving range determination process of determining, within the encrypted content generated by the generation process, a moving object range composed of one or more of the encrypted content units; a holding process of holding, as content information, a pair of serial number information representing serial numbers assigned to the one or more of the encrypted content units contained in the moving object range determined by the moving range determination process and the identification information generated by the generation process in the moving source; a copying process of copying a part of the encrypted content generated by the generation process that corresponds to the moving object range determined by the moving range determination process to the moving destination together with the identification information generated by the generation process; and an inactivation process of causing at least the part of the encrypted content generated by the generation process that corresponds to the moving object range determined by the moving range determination process to enter an inactive state in the moving source. As described above, according to one embodiment of the present invention, moving out and moving back of a part of a content are achieved. In particular, processing at that time is greatly simplified compared to known techniques. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are diagrams illustrating moving out according to a known technique; FIG. 3 is a diagram illustrating moving back according to a known technique; FIG. 4 is a diagram illustrating an example of an object of moving according to an inventive technique; FIGS. 5 to 7 are diagrams illustrating examples of moving out according to an inventive technique; FIGS. 8 to 10 are diagrams illustrating examples of moving back according to an inventive technique; FIG. 11 is a diagram illustrating an exemplary structure of a moving source device, i.e., an information processing apparatus according to one embodiment of the present invention; FIG. 12 is a flowchart illustrating an example of a move-out process performed by the moving source device of FIG. 11; and FIG. 13 is a flowchart illustrating an example of a move-back process performed by the moving source device of FIG. 11. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. Correspondence between the constituent features of the present invention and the embodiments that will be described in this specification taken in conjunction with the accompanying drawings is exemplified as follows. Note that this preliminary description is meant to confirm that an embodiment that supports the present invention is described in this specification and the accompanying drawings. Therefore, even if there is an embodiment that is described in this specification and the accompanying drawings but not described in this preliminary description as corresponding to a constituent feature of the present invention, that does not mean that that embodiment does not correspond to that constituent feature. Conversely, even if a certain embodiment is described in this preliminary description as corresponding to a certain constituent feature of the present invention, that does not mean that the certain embodiment does not correspond to any other constituent feature. An information processing apparatus (e.g., a moving source device 101 in FIG. 11) according to one embodiment of the present invention is an information processing apparatus that processes an encrypted content, the apparatus including a control section (e.g., a control section 301 in FIG. 11) configured to control the following processes to be performed independently in a specified order as a process for achieving moving out of at least a part of the encrypted content from a moving source (e.g., a storage section 306 or the like of the moving source device 101 in FIG. 11) to a moving destination (e.g., a moving destination device 2-A or 2-B in FIG. 11): a generation process of generating the encrypted content (e.g., an encrypted content 121 in FIG. 4) composed of a plurality of encrypted content units to which different serial numbers are assigned (in the case of FIG. 4, for example, encrypted content units 131-k to which serial numbers [k] are assigned), and generating, as identification information (e.g., identification information 122 in FIG. 4), data necessary for identifying and making reproducible the encrypted content; a moving range determination process of determining, within the encrypted content generated by the generation process, a moving object range composed of one or more of the encrypted content units (in the case of FIG. 7, for example, a moving object range for the moving destination device 2-A is an encrypted part 121-1, and a moving object range for the moving destination device 2-B is an encrypted part 121-2); a holding process of holding, as content information (in the case of FIG. 7, for example, content information 141-A composed of serial number information 151-A and the identification information 122, and content information 141-B composed of serial number information 151-B and the identification information 122), a pair of serial number information representing serial numbers assigned to the one or more of the encrypted content units contained in the moving object range determined by the moving range determination process and the identification information generated by the generation process in the moving source; a copying process of copying a part of the encrypted content generated by the generation process that corresponds to the moving object range determined by the moving range determination process to the moving destination together with the identification information generated by the generation process (in the case of FIG. 7, for example, a process of copying a pair of the encrypted part 121-1 and the identification information 122 to the moving destination device 2-A, and copying a pair of the encrypted part 121-2 and the identification information 122 to the moving destination device 2-B); and an inactivation process of causing at least the part of the encrypted content generated by the generation process that corresponds to the moving object range determined by the moving range determination process to enter an inactive state in the moving source (in the case of FIG. 7, for example, a process of causing the encrypted part 121-1 and the encrypted part 121-2 to enter an inactive state. Note that, in FIG. 7, the inactive state is indicated by gray while an active state is indicated by white). As control of the inactivation process, the control section may control only the part of the encrypted content generated by the generation process that corresponds to the moving object range determined by the moving range determination process to enter the inactive state in the moving source (e.g., a process of step S5 in FIG. 12) . The control section may further control the following processes to be performed independently in a specified order as a process for achieving moving back from the moving destination to the moving source: a collation process of collating the content information held in the moving source by the holding process with information obtained from the encrypted content and the identification information in the moving destination (e.g., processes of steps S21 and S22 in FIG. 13, and specifically, a process indicated by a white arrow in FIG. 8, for example); a deletion process of deleting the encrypted content and the identification information from the moving destination after the collation is successfully completed by the collation process (e.g., a process of step S23 in FIG. 13, and specifically, a process indicated by a cross in FIG. 9, for example); and an activation process of, after the collation is successfully completed by the collation process, causing a part of the encrypted content generated by the generation process that corresponds to the encrypted content in the moving destination to enter an active state in the moving source (e.g., a process of step S25 in FIG. 13, and specifically, a process indicated by the change in color of the encrypted part 121-1 from gray, as in FIG. 8, to white, as in FIG. 9). As control of the inactivation process, the control section may control the entire encrypted content generated by the generation process to enter the inactive state in the moving source (e.g., a process of step S6 in FIG. 12) . The control section may further control the following processes to be performed independently in a specified order as a process for achieving moving back from the moving destination to the moving source: a collation process of collating the content information held in the moving source by the holding process with information obtained from the encrypted content and the identification information in the moving destination (e.g., the processes of steps S21 and S22 in FIG. 13, and specifically, the process indicated by the white arrow in FIG. 8, for example); a deletion process of deleting the encrypted content and the identification information from the moving destination after the collation is successfully completed by the collation process (e.g., the process of step S23 in FIG. 13, and specifically, a process indicated by a cross in FIG. 10, for example); and an activation process of, after the collation is successfully completed by the collation process, causing the entire encrypted content generated by the generation process to enter the active state in the moving source if moving back of the encrypted content in the moving destination results in completion of moving back of the entire encrypted content generated by the generation process, but otherwise returning a right of reproducing the part of the encrypted content generated by the generation process that corresponds to the encrypted content in the moving destination (e.g., processes of steps S26 to S28 in FIG. 13, and a process illustrated in FIG. 10). An information processing method according to one embodiment of the present invention is an information processing method employed by an information processing apparatus (e.g., the moving source device 101 in FIG. 11) that processes an encrypted content, for achieving moving out of at least a part of the encrypted content from a moving source to a moving destination, the method including the steps of: generating the encrypted content composed of a plurality of encrypted content units to which different serial numbers are assigned, and generating, as identification information, data necessary for identifying and making reproducible the encrypted content (e.g., a process illustrated in FIG. 4); determining, within the encrypted content generated in the generating step, a moving object range composed of one or more of the encrypted content units (e.g., a process of step SI in FIG. 12); holding, as content information, a pair of serial number information representing serial numbers assigned to the one or more of the encrypted content units contained in the moving object range determined in the determining step and the identification information generated in the generating step in the moving source (e.g., a process of step S2 in FIG. 12); copying a part of the encrypted content generated in the generating step that corresponds to the moving object range determined in the determining step to the moving destination together with the identification information generated in the generating step (e.g., a process of step S3 in FIG. 12); and causing at least the part of the encrypted content generated in the generating step that corresponds to the moving object range determined in the determining step to enter an inactive state in the moving source (e.g., processes of steps S4 to S6 in FIG. 12), wherein the information processing apparatus executes processes of the above steps for achieving the moving out independently in a specified order. A program according to one embodiment of the present invention is, for example, a program for causing the steps of the above-described information processing method according to one embodiment of the present invention to be performed, and this program is executed by a computer that includes the control section 301 in FIG. 11, for example. First, with reference to FIGS. 4 to 10, outlines of techniques of moving out and moving back according to an embodiment of the present invention will be described. (These techniques will hereinafter be referred to as inventive techniques.) In FIGS. 4 to 10, a moving source device 101 different from the known moving source device 1 (see FIG. 1) is adopted as a moving source device. That is, the moving source device 101 is a moving source device to which the inventive techniques are applied. In other words, the moving source device 101 is an information processing apparatus according to one embodiment of the present invention. A specific exemplary structure of and exemplary processing by the moving source device 101 will be described later with reference to FIGS. 11 to 13. In contrast, known moving destination devices 2-A and 2-B are adopted as moving destination devices. Note that the known moving destination devices 2-A and 2-B are adopted simply in order to facilitate comparison of the inventive techniques with known techniques, and that, naturally, the moving destinations are not limited to the known moving destination devices 2-A and 2-B, but another information processing apparatuses according to an embodiment of the present invention or a given storage medium, for example, may also be adopted as the moving destination. It is assumed in the inventive techniques that a state illustrated in FIG. 4 is an initial state. Specifically, before performing moving out, the moving source device 101 encrypts a content that is a candidate for moving according to an "encryption system in which encryption involves assignment of serial number information" to generate an encrypted content 121 composed of a series of N+l (N is an integer of 1 or more) encrypted content units 131-k (k is an integer of 0 to N) each assigned with a serial number [k]. Here, the "encryption system in which encryption involves assignment of serial number information" refers to a system in which a content is segmented into N+l content units, the N+l content units are encrypted sequentially, and serial numbers of 0 to N+l are assigned to the resulting N+l encrypted content units. Any encryption key can be used in this system as long as the encrypted content units can be decrypted independently of each other. For example, the same key may be used for all the partial contents, or alternatively, different partial contents may be encrypted using different keys associated with the serial numbers. Thus, it is assumed in the example of FIG. 4 that key information A and the serial numbers [k] are used so that each of the encrypted content units 131-k can be decrypted independently of each other. That is, in the inventive techniques, the initial state is assumed to be a state in which the encrypted content 121 composed of the collection of the above encrypted content units 131-0 to 131-N is held, in a moving source as the candidate for moving, in the same file as that of identification information 122 that includes the key information A and a protected content ID, Here, as described below, the moving source may be either a storage medium (e.g., a hard disk) contained in the moving source device 101 or a storage medium (e.g., a removable medium) external to the moving source device 101. Note that, hereinafter, in order to simplify the description, the file being held in the moving source, which comprehends the file being held in the storage medium external to the moving source device 101, will be referred to as the file being held in the moving source device 101. According to the inventive technique, when starting from the initial state, at least a part of the encrypted content 121 is moved out as an object of moving, information (hereinafter referred to as content information) for identifying the object of moving at the time of moving back is held in the moving source device 101. Specifically, in the inventive technique, it is assumed that the unit of moving out is the encrypted content unit 131-k, taking advantage of the fact that each of the encrypted content units 131-k can be decrypted independently of each other. In this case, one or more of the encrypted content units 131-k can be the object of moving; and information (hereinafter referred to as serial number information) representing each of the serial numbers k assigned to the one or more of the encrypted content units 131-k and the identification information 122 for the original encrypted content 121 suffice to identify the one or more of the encrypted content units 131-k. Therefore, content information composed of the serial number information and the identification information 122 is held in the moving source device 101. Specifically, referring to FIG. 5, in the case where the object of moving is the entire encrypted content 121, for example, the moving source device 101 copies the encrypted content 121 as it is to the moving destination device 2-A together with the identification information 122, and deletes the encrypted content 121, which is the original data, within itself. At this time, the moving source device 101 generates content information 141 composed of serial number information 151 representing the serial numbers [0] to [N] and the identification information 122, and holds the generated content information 141 within itself. Thus, the moving out is completed. Meanwhile, in the case where the object of moving is a part of the encrypted content 121 (hereinafter referred to as an encrypted part), for example, referring to FIG. 6, in the case where the object of moving for the moving destination device 2-A is an encrypted part 121-1 and the object of moving for the moving destination device 2-B is an encrypted part 121-2, moving out is completed only by performing a simple process described below. As illustrated in FIG. 6, the encrypted part 121-1 is a collection of the encrypted content units 131-0 to 131-j to which the serial numbers [0] to [j], respectively, are assigned. Meanwhile, the encrypted part 121-2 is a collection of the encrypted content units 131-k to 131-N to which the serial numbers [k] to [N], respectively, are assigned. Here, j and k are integers that satisfy the following relationship: 0