Optical disk, optical disk recording and reproducing apparatus, method for recording, reproducing and deleting data on optical disk, and information processing system6938162Abstract A recording type optical disk on which data is recordable includes a data recording and reproducing area for recording data therein and reproducing data therefrom, and a read-only disk identification information area for recording disk identification information for identifying the optical disk therein. In the optical disk, the disk identification information is formed by removing a reflection film that is formed on the optical disk in a strip shape. The disk identification information includes an inherent disk identifier for each optical disk, and the data recording and reproducing area includes an area for recording encrypted data therein. The encrypted data is encrypted by using information including the disk identification information for identifying the optical disk as a key. Claims 1. An optical disk of recording type on which data is recordable, Description BACKGROUND OF THE INVENTION
In the above-mentioned optical disk, the disk identification information is preferably formed by removing a reflection film that is formed on the optical disk in a strip shape. In the above-mentioned optical disk, the disk identification information preferably includes an inherent disk identifier for each optical disk. In the above-mentioned optical disk, the data recording and reproducing area preferably includes an area for recording encrypted data therein, where the encrypted data is encrypted by using information including the disk identification information for identifying the optical disk as a key. In the above-mentioned optical disk, the encrypted data preferably includes content data which is at least one of image data and music data. In the above-mentioned optical disk, the encrypted data preferably includes a descramble key for decrypting a cipher which has been performed on content data. In the above-mentioned optical disk, the encrypted data preferably includes a descramble key for decrypting a cipher which has been performed on content data, and an error detection code for detecting an error in the descramble key. According to a second aspect of the present invention, there is provided an optical disk of recording type on which data is recordable,
According to a third aspect of the present invention, there is provided an optical disk of recording type on which data is recordable. The optical disk of the third aspect includes:
According to a fourth aspect of the present invention, there is provided an optical disk recording and reproducing apparatus for controlling at least one of:
The optical disk recording and reproducing apparatus of the fourth aspect comprises:
According to a fifth aspect of the present invention, there is provided an optical disk recording apparatus for recording content data on an optical disk of recording type on which data is recordable, wherein the optical disk includes an area for recording a disk identification information area for identifying the optical disk. The optical disk recording apparatus of the fifth aspect comprises reproducing means for reproducing the disk identification information from the disk identification information area, and recording means for recording at least partially encrypted data on the optical disk by using the reproduced disk identification information as a key. According to a sixth aspect of the present invention, there is provided an optical disk reproducing apparatus for reproducing content data from an optical disk of recording type on which data is recordable wherein the optical disk includes a disk identification information area for recording therein disk identification information for identifying the optical disk. The optical disk reproducing apparatus of the sixth aspect comprises reproducing means for reproducing the disk identification information from the disk identification information area, and decrypting means for decrypting at least partially encrypted data by using the reproduced disk identification information as a key after reproducing the at least partially encrypted data from the optical disk. According to a seventh aspect of the present invention, there is provided an optical disk recording and reproducing method for controlling at least one of:
The method of the seventh aspect includes the steps of:
According to an eighth aspect of the present invention, there is provided an optical disk recording method for recording content data on an optical disk of recording type on which data is recordable, wherein the optical disk includes a disk identification information area for recording therein disk identification information for identifying the optical disk. The method of the eighth aspect includes the steps of reproducing disk identification information from the disk identification information area, and recording at least partially encrypted data on the optical disk by using the reproduced disk identification information as a key. According to a ninth aspect of the present invention, there is provided an optical disk reproducing method for reproducing content data from an optical disk of recording type on which data is recordable wherein the optical disk includes a disk identification information area for recording therein disk identification information for identifying the optical disk. The method of the ninth aspect includes of the steps of reproducing the disk identification information from the disk identification information area, and
According to a tenth aspect of the present invention, there is provided an optical disk of recording type on which data is recordable. The optical disk of the tenth aspect includes a first information area for recording first disk information therein, a second information area for recording therein second disk information for identifying each optical disk, and a user data area for recording information data by irradiating a light beam onto the user data area. According to an eleventh aspect of the present invention, there is provided an optical disk of recording type on which data is recordable, wherein the optical disk has a sector structure comprising a plurality of sectors, wherein each of the plurality of sectors includes a sector header area and a main data area for recording encrypted data therein, wherein the sector header area includes a decipher key information area for recording therein at least one decipher key that is required for decrypting the encrypted data, and wherein a size of the decipher key information area is smaller than the size of each decipher key. According to a twelfth aspect of the present invention, there is provided an optical disk of recording type on which data is recordable,
According to a thirteenth aspect of the present invention, there is provided an optical disk recording method for recording data on an optical disk of recording type on which data is recordable. The method of the thirteenth aspect includes the steps of:
According to a fourteenth aspect of the present invention, there is provided an optical disk reproducing method for reproducing data from an optical disk of recording type on which data is recordable. The method of the fourteenth aspect includes the steps of reproducing and acquiring a decipher key index from a data recording area in which data to be reproduced is recorded in a file unit or an extent unit, reproducing and acquiring a decipher key corresponding to the acquired decipher key index, and reproducing data in the file unit or the extent unit which is encrypted by using the decipher key. According to a fifteenth aspect of the present invention, there is provided an optical disk deleting method for deleting data from an optical disk of recording type on which data is recordable. The method of the fifteenth aspect comprises:
According to a sixteenth aspect of the present invention, there is provided an information processing system comprising a data encrypting apparatus for encrypting data by using a cipher key, an optical disk recording and reproducing apparatus for recording a decipher key that is required for decrypting data on an optical disk of recording type, and for reproducing the recorded decipher key, and a control apparatus which is connected to the optical disk recording and reproducing apparatus and the data encrypting apparatus. The optical disk recording and reproducing apparatus of the seventeenth aspect comprises:
The data encrypting apparatus of the seventeenth aspect comprises encrypting means for encrypting the decipher key, and transmitting the encrypting decipher key to the control apparatus. The control apparatus of the seventeenth aspect comprises: receiving means for receiving the encrypted decipher key from the encrypting means of the data encrypting apparatus; and
The encrypting and decrypting means of the optical disk recording and reproducing apparatus receives the allocated and encrypted decipher key from the allocating means of the control apparatus, and decrypts the received encrypted decipher key. According to an eighteenth aspect of the present invention, there is provided an optical disk of read-only type for reproducing recorded data. The optical disk of the eighteenth aspect includes a data reproducing area for recording data therein, and a read-only disk identification information area for recording therein disk identification information for identifying the optical disk. The data reproducing area of the optical disk of the eighteenth aspect includes an area in which data is recorded that is encryptedby using information including the disk identification information for identifying the optical disk as a key. BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and features of the present invention will become clear from the following description when taken in conjunction with the preferred embodiments of the present invention with reference to the accompanying drawings throughout which like parts are designated by like reference numerals, and in which: FIG. 1 is a plan view illustrating a data recording area of an optical disk of recording type 100 of a first preferred embodiment according to the present invention; FIG. 2A shows a block diagram and a cross section view illustrating an apparatus configuration for forming a BCA 106 on the optical disk 100 shown in FIG. 1; FIG. 2B shows a cross section view of the optical disk 100 after formation of the BCA 106 on the optical disk 100 shown in FIG. 1, and a graph showing a strength of a reflected light in the horizontal direction; FIG. 3 is a diagram showing a recording format of the BCA 106 shown in FIG. 1; FIG. 4 is a diagram for illustrating a sector structure of sector data 401 within a user data area 102 shown in FIG. 1; FIG. 5 is a diagram illustrating a configuration of a key management information area 107 shown in FIG. 1; FIG. 6A is a block diagram showing a recording method for recording a descramble key and AV data in the sector data 401 shown in FIG. 1 according to a modified preferred embodiment of the first preferred embodiment; FIG. 6B is a block diagram showing a recording method for recording a key index to the descramble key and the AV data into the sector data 401 shown in FIG. 1 according to the first preferred embodiment; FIG. 7 is a block diagram showing a configuration of an optical disk recording and reproducing apparatus of a second preferred embodiment according to the present invention; FIG. 8 is a flowchart showing a recording process of AV data which is performed by a control CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7; FIG. 9 is a flowchart showing an allocating process of a key management information area which is performed by the control CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7; FIG. 10 is a flowchart showing a recording process of a descramble key which is performed by the control CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7; FIG. 11 is a flowchart showing a reproducing process of AV data which is performed by the control CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7; FIG. 12 is a flowchart showing an acquiring process of a descramble key which is performed by the control CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7; FIG. 13 is a block diagram showing a method for determining whether or not a descramble key is regular based on an encrypted descramble key according to a modified preferred embodiment of the first preferred embodiment; FIG. 14 is a diagram showing a configuration of the descramble area management table according to a modified preferred embodiment of the first preferred embodiment; FIG. 15A is a diagram showing whether or not copying or reproducing of contents is possible within the same region or in different regions in a case where a region identifier is recorded when a content is recorded in the first preferred embodiment; FIG. 15B is a diagram showing whether or not copying or reproducing of the content is possible in the same region or in different regions in a case where a region identifier is previously recorded when an optical disk is shipped in the first preferred embodiment; FIG. 16 is a plan view showing a data recording area of an optical disk 1101 of a third preferred embodiment according to the present invention; FIG. 17 is a waveform diagram showing signal waveforms of a reproduced signal 1201 and a reproduced binarized signal 1207 in a BCA reproducing circuit 1401 according to the third preferred embodiment; FIG. 18 is a block diagram showing a configuration of the BCA reproducing circuit 1401 according to the third preferred embodiment; FIG. 19 is a block diagram showing a configuration of an optical disk recording and reproducing system according to the third preferred embodiment; FIG. 20 is a block diagram showing a configuration of an optical disk recording and reproducing system of a fourth preferred embodiment according to the present invention; FIG. 21 is a plan view showing a data recording area of an optical disk 1601 of a fifth preferred embodiment according to the present invention; FIG. 22 is a block diagram showing a configuration of an optical disk recording and reproducing system according to the fifth preferred embodiment; FIG. 23 is a table showing a configuration of an ID adding table according to the fifth preferred embodiment; FIG. 24 is a plan view showing a data recording area of an optical disk 1101a according to a modified preferred embodiment of the third preferred embodiment; FIG. 25 is a plan view showing a data recording area of an optical disk 1601a according to a modified preferred embodiment of the fifth preferred embodiment; FIG. 26 is a block diagram showing a configuration of a user data area 2150 on the optical disk, and a configuration of an optical disk reproducing apparatus for decrypting an encrypted content from data in the user data area 2150 according to a sixth preferred embodiment of the present invention; FIG. 27 is a block diagram showing an arrangement of copyright control information and decipher key into a user data area, and an arrangement of an encrypted content into a main data area 2102 in the optical disk according to the sixth preferred embodiment; FIG. 28 is a block diagram showing an arrangement of a case where a unit for error correction is applied for a plurality of sectors in the optical disk according to the sixth preferred embodiment; FIG. 29 is a block diagram showing a configuration of a lead-in area 2401 and a user data area 2402 within an optical disk of a seventh preferred embodiment according to the present invention, and a configuration of an optical disk reproducing apparatus for decrypting an encrypted content from data stored in the lead-in area 2401 and the user data area 2402; FIG. 30A is a block diagram showing a data configuration in the case of indicating an unrecorded status by an initial value of a decipher key in the main data area 2102 of the lead-in area 2401 within the optical disk according to the seventh preferred embodiment; FIG. 30B is a block diagram showing a data configuration in the case of indicating a recorded status by a decipher key status table 2502 in the main data area 2102 of the lead-in area 2401 within the optical disk according to the seventh preferred embodiment; FIG. 31 is a block diagram showing an arrangement of a decipher key in the optical disk according to the seventh preferred embodiment; FIG. 32 is a block diagram showing a data configuration for managing data of an optical disk by a file management system of an eighth preferred embodiment according to the present invention; FIG. 33 is a flowchart showing a recording process of recording content that is required for copyright protection which is performed by the file management system according to the eighth preferred embodiment; FIG. 34 is a flowchart showing a reproducing process of reproducing content which is performed by the file management system according to the eighth preferred embodiment; FIG. 35 is a flowchart showing a deleting process of deleting content which is performed by the file management system according to the eighth preferred embodiment; FIG. 36 is a block diagram showing a configuration of an optical disk system of a ninth preferred embodiment according to the present invention; FIG. 37 is a block diagram showing a configuration of a user data area 2150 within an optical disk of a tenth preferred embodiment according to the present invention, a configuration of an optical disk recording apparatus for encrypting and recording a content into the user data area 2150, and a configuration of an optical disk reproducing apparatus for decrypting an encrypted content from data stored in the user data area 2150; FIG. 38 is a block diagram showing a configuration of a user data area 2402 within an optical disk of an eleventh preferred embodiment according to the present invention, a configuration of an optical disk recording apparatus for encrypting and recording a content into the user data area 2402, and a configuration of an optical disk reproducing apparatus for decrypting an encrypted content from data of the user data area 2402; and FIG. 39 is a block diagram showing a configuration of a user data area of a DVD-ROM, and a configuration of an optical disk reproducing apparatus for decrypting an encrypted content from data of the user data area according to the prior art. DETAILED DESCRIPTION OF THE INVENTION Preferred embodiments according to the present invention will be described below with reference to the attached drawings. First Preferred Embodiment FIG. 1 shows a plan view illustrating a data recording area of an optical disk 100 of recording type of the first preferred embodiment according to the present invention. The optical disk 100 of recording type is a recording medium which is capable of recording digital data, and includes a write-once type non-rewritable optical disk and a rewritable optical disk. Referring to FIG. 1, reference numeral 101 denotes a lead-in area for recording management information therein for the optical disk 100, and reference numeral 102 denotes a user data area for recording digital data therein which needs copyright protection, such as (a) AV data content including at least one of image data (including still picture images and animated picture images) such as movies or the like, and speech sound data such as music or the like; and (b) computer software. Reference numeral 103 denotes a lead-out area for recording defect management information or the like therein. The lead-in area 101 is constituted by a read-only area 104 in which data is recorded in a form of pre-pits, and a recording and reproducing area 105 which is a rewritable area with guide grooves. In this case, in the read-only area 104, a control area or the like which describes physical characteristics of the optical disk 100 is recorded in a form of pre-pits by the manufacturer. In the lead-out area 103 and the rewritable area 105, data for a writing test which is performed by an optical disk recording apparatus, and management information for managing defects on the optical disk 100 are recorded by an optical disk recording apparatus. In addition, on the inner peripheral side of the read-only area 104 in the lead-in area 101, a BCA 106 which is formed as disk individual information is once written on the optical disk 100 by the following well-known method, after completion of the optical disk 100 on which content has been recorded. FIG. 2A shows a block diagram and a cross sectional view illustrating an apparatus configuration when the BCA 106 is formed on the optical disk 100 shown in FIG. 1, and FIG. 2B shows a cross sectional view of the optical disk 100 and a graph showing an intensity of reflected light in the horizontal direction after the BCA 106 is formed on the optical disk 100 shown in FIG. 1. Referring to FIGS. 2A and 2B, an example of the optical disk 100 of double-side recording type is shown, and the optical disk 100 is constituted so that a recording layer 202, a reflecting layer 203, a bonding layer 204, a reflecting layer 205 and a recording layer 206 are inserted between two substrates 201 and 207. As shown in FIG. 2A, when the BCA is recorded on the optical disk 100, data after phase encoding modulation is recorded in a stripe form so as to overlap on pits by irradiating a laser beam in the form of pluses from a high power laser light source 211 onto, for example, the reflecting layer 205 of the optical disk 100 through a focusing lens 212 so as to eliminate or remove a part of the reflecting layer 205. As shown in FIG. 2B, upon reproducing the signals, the signals, which result from a lowered amount of reflecting light from the portions where the reflecting layer 205 is eliminated or removed, are intermittently reproduced. The BCA data is reproduced through the phase encoding demodulation after the reproduced signals are binarized. The BCA formed by such a recording system can record a disk identifier which is specific information for each optical disk 100, and further, the BCA has such a feature whereby it is impossible to falsify recorded data. FIG. 3 is a diagram which illustrates a recording format of the BCA 106 shown in FIG. 1. As shown in FIG. 3, a synchronization code (SY) 301, an error detection code (EDC) 302, an error correction code 303 and the like are recorded in the BCA 106 so as to improve the reading-out factor of the BCA data (DATA) 304. By connecting the plurality of BCA data 304, a disk identification information 305 is constituted. In the disk identification information 305, there are recorded types of data that are recordable into the user data area and the types of data which are reproducible from the user data area. It is impossible for the data of BCA 106 to be falisified, and therefore, a user's disk usage can be limited to a certain degree by means of the disk identification information that is recorded when the optical disk 100 is manufactured. FIG. 4 shows a sector structure of sector data 401 within the user data area 102 shown in FIG. 1. Referring to FIG. 4, the user data area 102 shown in FIG. 1 has a sector structure which is accessible by a unit of a certain amount, and the sector data 401 is constituted by a header 402, main data 403 and an error detection code 404. The main data 403 is an area in which AV data, computer data and the like are recorded. A data ID (data identifier) 405, an ID error detection code 406, scramble control information 407, key information 408 or the like are recorded in the header 402. A logical address for identifying sectors or the like is recorded in the data ID 405, and the ID error detection code 406 is provided for detecting errors in the data IDs. The scramble control information 407 is a flag for showing whether or not the main data has been scrambled, and information corresponding to a key for descrambling the main data 403 is recorded in the key information 408. As the information corresponding to the key, the descramble key itself (in the modified preferred embodiment of the modified preferred embodiment of the first preferred embodiment) or a key index (in the first preferred embodiment), which is a pointer to the descramble key which is recorded onto another area of the optical disk 100, are recorded. An example of FIG. 4 shows the case where a key index is recorded for referring to the descramble key recorded in the key management information area 107 shown in FIG. 1 which is another area of the optical disk 100. FIG. 5 shows a configuration of the key management information area 107 shown in FIG. 1. Referring to FIG. 5, the key management information area 107 is constituted by a key information area 501, a content information area 502 and a key index list area 503. In the key information area 501, the number of recorded key areas 504 is recorded, and the key information area 501 includes (a) a descramble key area 505, which is an area for recording the descramble key to descramble the scrambled AV data or the like, and (b) a key status area 506 for recording therein a recording status (indicating unused, area reservation, recorded or the like) of the descramble key which is recorded in the descramble key area 505. In the descramble key area 505, plurality of descramble keys are recorded, and a key index for representing the stored position in the descramble key area 505 is recorded in the key index list area 503. The above-mentioned plurality of descramble keys are possible to be referred to by this key index. In the key status area 506, the status information for representing the recording status of the descramble keys is stored at a position which is possible to be referred to by the key index. In the content information area 502, the contents which are recorded on the optical disk 100 are registered when copyright protection is necessary, and the information with respect to keys which are used for the contents is registered. The number of contents 507 registered in the key index list area 503 and content information 508 for the content number are recorded in the content information area 502. In addition, a content ID for identifying the content, the number of descramble keys which are used for the content, and the pointer to the key index list 509 which records the used keys are each recorded in the content information 508. The key index list area 503 is an area for recording indexes to refer to the keys which are used for the content in a form of in content unit. A key index for referring to the entire recording area of the descramble keys which are used for the content is recorded in the key index list area 503. The optical disk of recording type 100 constituted in this way makes it possible to control the recording operation and the reproducing operation in accordance with the protection level or the usage level of the copyright held by the contents. Controlling the recording and reproducing operations according to the designated protection or usage level is achieved by recording information for representing conditions or a status for disk usage on the disk identification information which is difficult to rewrite such as a region identifier, a data category identifier and a disk identifier upon manufacturing, and by detecting such information by an optical disk and reproducing apparatus. Since data is recorded in such a manner so as to make it difficult to rewrite so that a user cannot change the data, even in the case where the copyright protected content is copied to another optical disk, the disk identification information cannot be copied while it remains possible to copy the user data area. Accordingly, by recording the data as being scrambled by using the disk identification information on the optical disk, such data on the optical disk can be prevented from being reproduced correctly since there exists a user data area which cannot be descrambled in an optical disk having different disk identification information. FIG. 15A shows a diagram showing whether or not copying or reproducing the content is possible in the same region as well as in a different region in the case where a region identifier is recorded when the content is recorded in the first preferred embodiment, and FIG. 15B shows a diagram indicating whether or not the copying or the reproduction of the content is possible in the same region as well as in a different region in the case where a region identifier is recorded in advance when the optical disk is shipped in the first preferred embodiment. For example, as shown in FIG. 15A, in the case where a region identification code is not recorded when the optical disk is shipped, and the region identifier, which represents the region where the contents are available when the contents are recorded, is recorded in a recording and reproducing area, the usage can be prevented in another region. However, the contents are recordable in a disk (for a region RC2 shown in FIG. 15A) to be used in another region, and it is therefore possible to reproduce the content correctly. A recording medium in which a digital copying of the content is possible is provided with a tax imposing system to protect the benefit of copyright holders which collect an added charge when the optical disk is sold. However, the added charge differs according to a particular country and in the case where the recording medium to be used in another country is utilized unjustly, the possibility remains that the copyright holders will not be able to share in the appropriate profit. As shown in FIG. 15B, by recording in advance at the time of shipping in such a way that the region identifier cannot be falsified, copying or reproduction of the content to an optical disk to be used in another region can be prevented. In a manner similar to that as described above, in the case where a data category identifier is recorded as disk identification information, copying or reproduction of the content to the disk on which the data is recordable and reproducible can be limited by comparison between category identifiers which the record data have. In the case where an inherent disk identifier for each optical disk is recorded as disk identification information, the recorded data can be made available only by the optical disk by encrypting the recorded data with the disk identifier. In the present preferred embodiment, the data which is scrambled by the disk identification information may be AV data or computer data which needs copyright protection, or the scrambled data may be descramble keys for descrambling scrambled AV data or computer data. FIG. 13 is a block diagram showing a method for judging whether or not a descramble key is a regular descramble key based on the encrypted descramble key according to the modified preferred embodiment of the first preferred embodiment. As shown in FIG. 13, the data which is obtained by adding an error detection code for detecting errors in the descramble key to the descramble key may be scrambled by using disk identification information so as to calculate an encrypted descramble key which may be recorded on the optical disk. In the optical disk reproducing apparatus, the encrypted descramble key is decrypted into a descramble key and an error detection code so as to judge whether or not the decrypted descramble key is a regular descramble key by detecting errors based on the parity check in the decrypted error detection code. For example, in the case of descrambling by using different disk identification information, an error descramble key is produced so that an irregular copy can be detected by checking the error detection code for determining that the decrypted descramble key is not a regular descramble key. As another method for recording disk identification information, by preparing stampers which are formed with a plurality of types of disk identification information in the form of pre-pits and by forming an optical disk from each of the stampers, different usage limitations may be given to respective optical disks which are formed from different stampers. In addition, by scrambling the disk identification information by using a secret key and by recording the scrambled disk identification information on the optical disk, the protective level of the copyright described in the disk identification information is kept unknown to the users, and as a result, the copyright protection is further enforced. The case where the descramble key itself is recorded as the information corresponding to the key described in FIG. 4 (in the modified preferred embodiment of the first preferred embodiment) and the case where the key index, which is a pointer to the descramble key which is recorded in another area of the disk, is recorded (in the first preferred embodiment) will be described with reference to FIGS. 6A and 6B. FIG. 6A is a block diagram showing a recording method for recording a descramble key and AV data in the sector data 401 shown in FIG. 1 according to the modified preferred embodiment of the first preferred embodiment, and FIG. 6B shows a block diagram showing a recording method for recording a key index and AV data to a descramble key in the sector data 401 shown in FIG. 4 in the user data area 102 shown in FIG. 1 according to the first preferred embodiment. In the case of FIG. 6A, the main data 403 and the descramble key which is key information 408a which is required for descrambling of the main data 403 are recorded in the same sector data 401. Thus, it is necessary to acquire a descramble key which is required for descrambling when AV data are recorded. That is to say, the acquisition or the purchase of the key itself is indispensable or inevitable when AV data are recorded. On the other hand, in the case of FIG. 6B, the main data 403 and the key index, which is the key information 408 for referring to the descramble key area for recording the necessary information for descrambling the main data 403, are recorded in the same sector data 401, and the descramble key is recorded in an area which is designated by the key index. When the AV data are recorded, the key ID indicating which key among the keys used in the recorded content can descramble is acquired, and the key information 408 is acquired. The key information 408 is a key index corresponding to the key ID from the key index list that is included in the content information, which is recorded together with the main data 403. The recording of the descramble key is performed when the descramble key is obtained to be recorded in the descramble key area that is shown by the key index corresponding to the key ID. As a result, AV data and the descramble key corresponding to the AV data can be recorded independently. That is to say, the recording of AV data and the acquisition or purchase of the key can be carried out independently so that the acquisition or the purchase of the key is not necessarily required when the AV data are recorded. It therefore becomes possible for the user to utilize a method for recording the content and acquiring the key when the content is actually reproduced. FIG. 14 shows a configuration view of a descramble area management table according to a modified preferred embodiment of the first preferred embodiment. In the above-mentioned preferred embodiments, in order to correlate the encrypted content with the descramble key for descrambling its cipher, the cases in which the key index is recorded for referring the descramble key to the same sector data 401 are described. However, the descramble area management table shown in FIG. 14, which manages the corresponding relationships between the address range of the sectors in which the encrypted content is recorded and the descramble key, may be used. This descramble area management table represents the address range of the sector in which the encrypted content is recorded with the starting address and the completion address, and when the data of the sector is reproduced, the descramble key is referred to and then the encrypted content is descrambled. In order to acquire the recorded content and the descramble key which is used for the recorded content, the content ID that makes the content identifiable is utilized. As shown in FIG. 5, in the content information which is recorded in the content management list within the content information area 502 which is recorded on the optical disk, the content ID and the list of the descramble key used for the content are recorded. By having a list configuration where a plurality of descramble keys can be used for one piece of content, such services are made available so that a part of the content or a part of the software can be sold. In the modified preferred embodiment described above with reference to FIG. 13, when the data where the descramble key to which the error detection code such as a check sum or a cyclic redundancy check code is added thereto is scrambled by the disk identification information and is copied unjustly onto another disk, the descramble key can be detected as an error by being descrambled with different disk identification information. In such a case, it is also possible to acquire a descramble key that is scrambled by disk identification information which is recorded on the optical disk, and to form a disk which can be reproduced correctly by replacing that descramble key with the acquired descramble key. The key management information area 107 shown in FIG. 1 is recorded in a lead-in area 101 which is rewritable. Generally, the user data area 102 comprises a user area which is accessible from a drive apparatus of a personal computer, and a spare area for the defect sector on an optical disk. Moreover, for the conventional READ command and WRITE command, only the user area can be accessible as a logical continuous area. By placing the key management information in the lead-in area 101, direct access from the drive apparatus of the personal computer or the like can be prevented so that acquiring a key for descrambling the scrambled AV data or the like from the personal computer can be made impossible. Second Preferred Embodiment FIG. 7 shows a block diagram illustrating a configuration of an optical disk recording and reproducing apparatus of the second preferred embodiment according to the present invention. This optical disk recording and reproducing apparatus is provided for recording contents of AV data such as image data or music data which require copyright protection for the optical disk 100 according to the first preferred embodiment. Referring to FIG. 7, reference numeral 701 denotes an optical disk of the first preferred embodiment, reference numeral 702 denotes an optical head which is an optical pickup that is constituted by a semiconductor laser and optical elements, and reference numeral 703 denotes a recording and reproducing control circuit for controlling the operation of the semiconductor laser of the optical pickup 702 and for binarizing the reproduced signals. Reference numeral 704 denotes a modulating and demodulating circuit for digitally modulating digital data to be recorded and digitally demodulating the binarized reproducing signals, and reference numeral 705 denotes an error detecting and correcting circuit for error detection and correction processing of errors caused by scratches, dust or the like on the optical disk 701 and for performing error correction code generation processing which is required for the error detection and correction processing. Reference numeral 706 denotes a buffer memory of a RAM that is used for a working memory and a data buffer memory of the error detecting and correcting circuit 705, reference numeral 707 denotes a descramble circuit for descrambling scrambled recorded AV data, and reference numeral 708 denotes an MPEG decoding circuit for expanding compressed recorded dynamic image data or the like. Reference numeral 709 denotes an output circuit for D/A converting expanded image data so as to generate and output video signals and audio signals, reference numeral 710 denotes a control CPU for controlling the entire operation of the optical disk recording and reproducing apparatus, and reference numeral 711 denotes a communication circuit for acquiring a descramble key for descrambling the cipher placed in the contents. Reference numeral 712 denotes a data receiving circuit for receiving digital data of the encrypted content such as image data and music data from a communication terminal apparatus such as a set-top box. A data recording operation of the optical disk recording and reproducing apparatus of FIG. 7 constituted as described above will now be described. The digital data of the encrypted contents such as image data or music data that are transmitted from the communication terminal apparatus such as a set-top box or an MPEG encoder are temporarily stored in the buffer memory 706 after being received by the data receiving circuit 712. The error detecting and correcting circuit 705 generates error detection and correction code that are required for the error detection and correction process caused by scratches or dust on the optical disk 701 in the digital data of the stored contents so as to reconfigure the record data. For the error detection and correction code, a code such as a well-known Reed-Solomon code is used. In this case, the reconstituted record data includes digital data of content and error detection and correction code. The modulating and demodulating circuit 704 uses a modulation system such as an 8/16 modulation system upon recording, and digitally modulates the record data. Also, the recording and reproducing control circuit 703 modulates the intensity of the power of the laser beam that is outputted from the optical head 702 according to the record data modulated digitally so that the laser is irradiated onto the optical disk 701 so as to record the record data onto the optical disk 701. FIG. 8 shows a flowchart indicating an AV data recording process that is carried out by the control CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7. Referring to FIG. 8, first of all, in step S801, the disk identification information of the lead-in area 101 is reproduced prior to recording of the AV data from the optical disk 701. Then, in step S802 it is determined whether or not the digital data of the contents to be recorded at the present time are recordable from the type or class of data that is recordable in the user data area 102 which are recorded in the disk identification information. In the case of YES in step S802, the recording operation proceeds to step S803, while in the case of NO, the recording operation is stopped in step S810, whereupon the recording process of the AV data is completed. In step S803, the data of the sector where the key management information is recorded in the lead-in area 101 is reproduced, and in step 5804 it is determined whether or not an area is allocated for the key information that is required for recording the contents in the reproduced key management information. In the case of NO in step S804, after allocating an area for recording the key information in the key management information area 107, the recording operation proceeds to step S806. On the other hand, in the case of YES in step S804 the recording operation proceeds directly to step S806. In the case where the content is recorded, the control CPU 710 of the optical disk recording and reproducing apparatus receives the record data of the encrypted content and information with respect to the descramble key for descrambling the cipher via the data receiving circuit 712 from the communication terminal apparatus. In this case, the information with respect to the key is the key itself that is used for the contents or a key ID for indicating to which key the information corresponds from among the keys that are used in the entire contents. In the case where the key ID is received, in step S806, the received key ID is converted into a key index, which is a pointer for indicating an area where a descramble key corresponding to the key ID is recorded, and the converted descramble key is placed in a header area of the sector where the data of the contents to be decrypted with the descramble key is recorded. Then, in step S807, the control CPU 710 carries out the following record data processing by controlling the recording and reproducing control circuit 703, the modulating and demodulating circuit 704, and the error detecting and correcting circuit 705. In this record data processing, the codes for the error detection and correction are added to the sector data which is desired to be recorded. Then, the sector data with such codes added thereto are digitally modulated by using a modulation system, such as a well-known 8/16 modulation system, so that the optical head 702 is controlled to locate at a predetermined recording position, and the intensity of the laser beam is modulated according to the record data that is digitally modulated. By doing this, the record data is recorded on the optical disk 701, and in addition, in step S808, it is determined whether or not the recording of the contents has been completed. In the case of NO, i.e., recording of the contents has not been completed, the recording process goes back to step S806 so as to repeat the above-mentioned processing. In the case of YES in step S808, the updated key management information is recorded in the key management information area 107 on the optical disk 701 in step S809, and then, the recording process of the AV data is completed. FIG. 9 shows a flowchart illustrating an allocating process of the key management information area that is carried out by the control CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7. This allocating process is provided for allocating areas for recording a descramble key prior to recording data of the content. Referring to FIG. 9, in step S901, the information with respect to the key of the content recorded from an electronic program guide or the like (including the number of used descramble keys) is acquired, for example, and then, in step S902, the key management information within the key management information area 107 that is recorded in the optical disk 701 is reproduced. Then, in step S903, empty areas of the descramble key area 505 are searched from the key status area 506 so as to determine whether or not the descramble key that is used in the content to be recorded can be recorded. In the case of NO in step S903, the recording operation is stopped in step S907, and then, the allocating process is completed. On the other hand, in the case of YES in step S903, the contents to be recorded are registered in the content list within the content information area 502 so that recording areas are allocated by setting area reservation flags in corresponding key status areas so as to reserve an area that is required for the recording of a descramble key in the descramble key area 505 in step S905. In addition, in step S906, a key index indicating allocated areas for recording descramble keys are formed as a key list, and then, after a pointer set as the content information is allocated, the allocation process is completed. FIG. 10 shows a flowchart illustrating a recording process of the descramble key that is carried out by the control CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7. This recording process is provided for recording a descramble key that is acquired from a key management center in the optical disk 701. Referring to FIG. 10, first of all, in step S1001, after the disk identification information of the lead-in area 101 on the optical disk 701 is reproduced, the disk identification information and the key ID for identifying keys that are required for the descrambling of the desired content are transmitted to the key management center via the communication circuit 711 so as to acquire a descramble key from the key management center in step S1002. In the key management center, a descramble key that is required for the descrambling of the content from the given key ID are selected so that the descramble key is encrypted by using the information, such as the transmitted disk identification information, and is then returned. After the descramble key corresponding to the key ID is acquired via the communication circuit 711 from the key management center in step S1003, the data of the key management information area 107 is reproduced so that the key index for indicating an area for recording the descramble key is acquired from the key index list that is indicated by key ID from among the data within the reproduced key management information area 107 in step S1004. Then, in step S1005, the descramble key that is acquired above is allocated in the descramble key area that is indicated by the key index, and an acquired flag for indicating a key that is acquired in the corresponding key status area 506 is set. In addition, in step S1006, whether or not the acquisition of all the keys are completed is determined, and then, in the case of NO in step S1006, the above-mentioned process is repeated by returning to step S1003. On the other hand, in the case of YES in step S1006, the updated key management information is recorded in the key management information area 107 in step S1007, and then, the descramble key recording process is completed. Next, the data reproducing operation of the optical disk recording and reproducing apparatus of the second embodiment will be described with reference to FIG. 7. The digital data that is recorded on the optical disk 701 is reproduced as follows. A laser beam from the semiconductor laser from the optical head 702 is irradiated onto the optical disk 701, so that, at that time, the reflected light which is reflected on the optical disk 701 is entered into the recording and reproducing control circuit 703 via the optical head 702. The recording and reproducing control circuit 703 generates and outputs a generated reproduced binarized signal to the modulating and demodulating circuit 704 by carrying out amplification and by a binarizing process after photoelectrically converting the entered reflected light. The modulating and demodulating circuit 704 digitally demodulates the digitally modulated signal into a digital signal by using a modulating system such as a well-known 8/16 modulating system upon recording, and then, the modulating and demodulating circuit 704 outputs the resultant digital signal to the error detecting and correcting circuit 705. Then, the error detecting and correcting circuit 705 uses the buffer memory 706 as a working memory so as to carry out detecting and correcting processes of the errors that are caused by scratches or dust on the optical disk 701. This error detecting and correcting process is carried out by decoding, for example, with a well-known Reed-Solomon code. The reproduced data which are processed for error detection and correction are outputted to the descramble circuit 707 for carrying out the descramble process. The descramble circuit 707 uses the descramble key of the key management information area 107 that is reproduced prior to the data reproduction in advance, and performs a descramble process for the reproduced data, which is then outputted to the MPEG decoding circuit 708. Then, the MPEG decoding circuit 708 expands the compressed dynamic image data and music data, and then, the expanded data is outputted to the output circuit 709 by the MPEG decoding circuit 708. In addition, the output circuit 709 D/A converts the inputted expanded data into video and audio signals, and outputs the resultant video and audio signals to upper-level apparatuses such as a television set, an audio device or the like. FIG. 11 shows a flowchart illustrating a reproduction process of AV data that is carried out by the control CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7. Referring to FIG. 11, first of all, in step S1101, prior to the recording of the AV data from the optical disk 701, the disk identification information within the lead-in area 101 is reproduced, and in step S1102, it is determined whether or not the content that is desired to be reproduced at present is reproducible from the types of reproducible data that are recorded in the disk identification information. In the case of NO in step S1102, the reproducing operation is stopped in step S1112, and then, the reproducing process of the AV data is completed. On the other hand, in the case of YES in step S1102, the data in the sector where the key management information is recorded within the key management information area 107 of the leadin area 101 are reproduced, and it is determined whether or not the key information that is required for the reproduction of the content has been recorded in the key management information that is reproduced in step S1104. In the case of YES in step S1104, the reproducing information proceeds to step S1106 directly. On the other hand, in the case of NO in step S1104, in step S1105, a descramble key is acquired via the communication circuit 711 from the key management center which manages the keys, and the descramble key is recorded in the key management information area 107 on the optical disk 701. Then, the reproducing operation proceeds to step S1106. Next, in step S1106, the control CPU 710 makes the optical head 702 move to the user data area of the optical disk 701, and controls the recording and reproducing control circuit 703, the modulating and demodulating circuit 704 and the error detecting and correcting circuit 705 so that the AV data are reproduced. Then, in step S1107, the descramble key that is required for the descrambling of the sector data is acquired from the descramble key area 505 that is indicated by the key index included in the header of the reproduced sector. Then, in step S1108, the scrambled information for the descramble key is decoded by descrambling by means of the disk identification information. In addition, in step S1108, by checking the error detection code that is added to the descramble key, it is determined whether or not the descramble key has an error. In the case of YES in step S1108, the contents are judged as obtained irregularly (or the contents are copied irregularly), the reproducing operation is stopped in the step S1112, and then, the reproducing process of the AV data is completed. On the other hand, in the case of NO in step S1108, the data of the content is descrambled by the descramble key in S1109, and the descrambled AV data is outputted to the MPEG decoding circuit 708 in step S1110. Then, the control CPU 710 MPEG-expands the descrambled AV data through a predetermined MPEG system by controlling the MPEG decoding circuit 708 and the output circuit 709, and then, the MPEG-expanded AV data is D/A converted into video signals and audio signals to be outputted to upper-level devices such as a television set, an audio device or the like. Then, in step S1111, it is determined whether or not the reproduction of the content is completed. In the case of NO in step S1111, the reproducing operation returns to step S1106 so as to repeat the above-mentioned process. On the other hand, in the case of YES in step S1111, the reproducing process of the AV data is completed. In the case where an error is detected in step S1109, the content is regarded as being obtained irregularly, for example, the content is regarded as being copied irregularly, and the reproducing operation is stopped. However, the key information may be acquired from the key management center which manages the keys via the communication circuit 711 and recorded in the key management information area 107 on the optical disk 701 by carrying out the process of step S1105 in the same way as the case where a key is not recorded. By doing this, even the copied AV data can become reproducible by obtaining the key in a regular procedure. FIG. 12 shows a flowchart illustrating an acquiring process of a descramble key that is carried out by the control. CPU 710 of the optical disk recording and reproducing apparatus shown in FIG. 7. This acquiring process is provided for reproducing descramble keys from the reproduced key index, and this acquiring process is carried out prior to the reproducing process of the AV data as shown in FIG. 11. Referring to FIG. 12, first of all, in step S1201, it is determined whether or not the data in the reproduced sector area is scrambled by the scramble control information. In the case of NO in step S1201, the acquiring process proceeds to step S1206. On the other hand, in the case of YES in step S1201, a key index is acquired by reproducing key information that is recorded in the same sector area as the above-mentioned sector area in step S1202, and then, the descramble key that is indicated by the above-mentioned key index is acquired from the descramble key area 505 in step S1203. Afterwards, in step S1204, the acquired descramble key is descrambled by using the disk identification information, and it is determined whether or not an error exists in the descramble key by checking the error detection code. In the case of YES in step S1204, the reproducing operation is stopped in step S1205, and the acquiring process of the descramble key is completed. On the other hand, in the case of NO in step S1204, the reproducing operation proceeds to step S1206. When the reproduced sector is not scrambled or when an error is not found to exist as a result of descrambling the descramble key by the disk identification information, permission for the reproducing operation is granted in step S1206, the data of the reproduced sector is outputted, and then, the acquiring process of the descramble key is completed. As described above, in the optical disk and in the optical disk recording and reproducing apparatus of the preferred embodiments according to the present invention, the recording and reproducing operations can be controlled by the user by using disk identification information for read-only that are made at a disk manufacturing stage. In addition, by scrambling a part of the data by using the above-mentioned disk identification information, normally reproducing data on the disk where the user data area is physically copied can be prevented. Also, by allocating the descramble key that is required for the data descrambling in a different area from the area for the data, the recording of the content and the recording of the descramble key can be carried out independently. Thus, by recording the contents and by acquiring the descramble key if necessary, for example, when the data of the content are reproduced, the content can be maintained in a reproducible state or status. At this time, by scrambling the descramble key with the disk identification information, an irregular usage through physical copying can be explicitly prevented in the same way as that described above. In addition to this, a disk that is copied irregularly could become an optical disk which can be reproduced normally by formally acquiring the descramble key that is scrambled with the disk identification information of the optical disk from the key management center and by recording the acquired descramble key in the optical disk. Although already encrypted data of the content that is inputted to the optical disk recording and reproducing apparatus are described above, by providing a circuit for encrypting the content within the optical disk recording and reproducing apparatus, the same effects can be obtained by encrypting the data of the inputted contents and by recording that data on the optical disk. Although in the second preferred embodiment, by encrypting only the descramble key which is required for decrypting the encrypted content by using the disk identification information, copying between the disks having different disk identification information is prevented, copying can be prevented by encrypting the content itself by using the disk identification information. In addition, by encrypting the disk identification information by using a secret key, it becomes possible to make the irregular decrypting of the content that is recorded on the disk more difficult. Advantageous Effects of First and Second Preferred Embodiments An optical disk of the first and second preferred embodiments according to the present invention records the disk identification information by carrying out the recording operation and the reproducing operation into the user data area for each optical disk in a read-only area which is not rewritable. Therefore, the optical disk of the first and second preferred embodiments can control the recording operation and the reproducing operation of the contents onto the optical disk by the user by using the information that is recorded upon manufacturing the optical disk. An optical disk of the preferred embodiments according to the present invention can prevent the disk identification information from being copied so as to make the correct decoding and reproduction of the data impossible even in the case where the user data area information is copied by the user onto a different recording-type of optical disk by recording, the encrypted data in the user data area of the optical disk with a key of the disk identification information of read-only which is impossible to be rewritten. An optical disk of the first and second preferred embodiments according to the present invention makes it possible to carry out independently (a) an acquisition of the data which needs copyright protection such as movies and music, and (b) an acquisition of the descramble key for decrypting the encryption by recording the encrypted data and the descramble key for decrypting the encryption in different sector areas. In addition, by encrypting and recording the descramble key with a key of the disk identification information, even in the case where the user data area information is copied onto another recording-type optical disk by the user, the disk identification information cannot be copied, and a correct decoding and reproduction of the data becomes impossible. Further, by acquiring and recording the encrypted descramble key with a key of the disk identification information on the optical disk where it is copied, a correct decoding and reproduction of the data can be made possible. Third Preferred Embodiment Next, an encrypted content recording and reproducing method of a third preferred embodiment according to the present invention will be described with reference to the drawings. FIG. 16 shows a plan view illustrating a data recording area of an optical disk 1101 of the third preferred embodiment according to the present invention. Referring to FIG. 16, reference numeral 1101 denotes a recording medium which can record digital data, and which is a recording-type optical disk such as a rewritable or non-rewritable optical disk, reference numeral 1102 denotes a control user data area in which disk information is recorded in a form of minute concavo-convex pits, and reference numeral 1103 denotes a user data area in which the user records data by irradiating a light beam of a laser onto the optical disk. Reference numeral 1104 denotes an BCA in which disk ID is recorded. In the BCA 1104, a recording film on minute concavo-convex pits in an inner periphery section of the control user data area 1102 is trimmed by partially irradiating a laser beam of a pulse laser such as a YAG laser or the like onto the recording film so that a plurality of trimming areas 1105 are formed in an elongated shape in the radius direction to thereby record a disk ID which is the descrambled identification information. FIG. 17 is a waveform diagram showing a signal waveform of a reproduced signal 1201 and a reproduced binarized signal 1207 in a BCA reproducing circuit 1401 according to the third preferred embodiment. FIG. 18 shows a block diagram illustrating a configuration of the BCA reproducing circuit 1401 according to the third preferred embodiment. FIG. 17 shows a reproducing signal 1201 when data of the BCA 1104 is reproduced In FIG. 18, reference numeral 1301 denotes an optical pickup, reference numeral 1302 denotes a pre-amplifier, reference numeral 1303 denotes a low-pass filter (LPF), reference numeral 1304 denotes a binarizing circuit, and reference numeral 1305 denotes a demodulation circuit. Referring to FIG. 18, a laser beam that is outputted from the optical pickup 1301 irradiates the BCA 1104 of the optical disk 1101, and the reflected light is photoelectrically converted by the optical pickup 1301. Thereafter, an electric signal which has been photoelectrically converted is amplified by the pre-amplifier 1302 so as to obtain a reproduced signal 1201. In this case, the reproduced signal 1201 shown in FIG. 17 has a level corresponding to the concavo-convex pits of the control user data area 1102, and in this reproduced signal 1201, each of reference numerals 1202, 1203 and 1204 denotes a trimming portion where signals in a form of concavo-convex pits drop out when the recording film is removed by the trimming process by the pulse laser. This trimming process is carried out by the manufacturer of the optical disk. Referring back to FIG. 18 for a description of the BCA reproducing circuit 1401, the reproduced signal 1201 is inputted to the low-pass filter 1303, which then removes the modulated signal that is formed by the concavo-convex pits. Thereafter, the low-pass filter 1303 outputs a resultant signal to the binarizing circuit 1304. The reproduced signal that is inputted into the binarizing circuit 1304 is binarized by using a slice level 1206 which is a level that is significantly lower than the slice level 1205, instead of the normal slice level 1205 which binarizes a signal of control user data area 1102 so as to obtain the reproduced binarized signal 1207. The reproduced binarized signal 1207 that is outputted from the binarizing circuit 1304 is demodulated by a demodulation circuit 1305 so as to obtain the disk ID signal 1306. As described above, by adding the disk identification information for identifying an optical disk, management of the optical disk can be easily implemented. Also, by recording the BCA 1104 in a form of concavo-convex pits, the information for identifying the optical disks within the BCA 1104 can be prevented from being easily falsified. In addition, since the control user data area 1102 and the BCA 1104 shown in FIG. 16 are adjacent to one another, the data of the BCA 1104 can be continuously reproduced when the data of the control user data area 1102 are reproduced, or the data of the control user data area 1102 can be continuously reproduced when the data of the BCA 1104 are reproduced. Therefore, it becomes possible to accelerate the process for obtaining the information of the BCA 1104 for identifying optical disks quickly by the CPU when, for example, the optical disk is started up, and for recording the encrypted content. Although the BCA 1104 of the third preferred embodiment is formed so as to trim the recording film in a form of concavo-convex pits in the inner periphery section of the control user data area 1102, the recording film, which constitutes an optical disk of recording type that is either a rewritable or non-rewritable optical disk, is easily affected by heat as compared with the reflecting film that is formed on a read-only optical disk. By trimming the inner periphery section of the control user data area 1102, the user data area 11103 can be protected from the heat that is emitted upon trimming as compared with the case where the outer periphery section is trimmed. Also, the reason why the BCA 1104 is formed on the inner peripheral side of the control user data area 1102 is that a margin should be taken into consideration in the case where the diameter of the spot of a laser beam changes due to the instability of a focusing servo circuit of the laser device. The data that are recorded in the BCA 1104 before trimming may be recorded in the control user data area 1102. The data that are recorded in the BCA 1104 are also recorded in the control user data area 1102, and this leads to the above-described data of the control user data area 1102 being protected from the trimming. In addition, when the data that are recorded in the BCA 1104 are recorded continuously and repetitively from the BCA 1104 to the control user data area 1102, the position of the BCA 1104 can be predicted by finding the above-described data of the control user data area 1102. Next, the procedure for recording the encrypted content by the disk ID through a network on an optical disk 1101 having the above-mentioned BCA 1104 will be described. In the third to fifth preferred embodiments, a network means, for example, the Internet, the public telephone line or other communication lines such as leased lines or circuits. FIG. 19 shows a block diagram illustrating a configuration of an optical disk recording and reproducing system according to the third preferred embodiment, and illustrates an apparatus configuration for recording encrypted contents on an optical disk of recording type 1101, which is either a rewritable or non-rewritable optical disk having the above-mentioned BCA 1104. Referring to FIG. 19, an optical disk recording and reproducing system is constituted by comprising an optical disk recording and reproducing apparatus 1410 and an encryption section 1406 that are connected to each other through a network 1405 such as the Internet. The optical disk recording and reproducing apparatus 1410 comprises an optical pickup 1301, a BCA reproducing circuit 1401, the Internet (interface) 403, a recording circuit 1411, a data reproducing section 1412, and an encryption decoder 1413. Also, the encryption section 1406 comprises an interface 1404, a content memory 1407, and an encryption encoder 1408. First of all, a laser beam that is outputted from the optical pickup 1301 irradiates, for example, the BCA 1104 of the RAM type optical disk 1101, and then, after the reflected light is photoelectrically converted by the optical pickup 1301, a reproduced signal which has been photoelectrically converted is inputted to the BCA reproducing circuit 1401. The BCA reproducing circuit 1401 reproduces a disk ID signal 1402 within the BCA based on the inputted reproduced signal, outputs the reproduced disk ID signal 1402 to the encryption decoder 1413, and also simultaneously outputs the same disk ID signal 1402 to the encryption encoder 1408 of the encryption section 1406 via the interface 1403 and 1404 as well as the network 1405. The encryption encoder 1408 encrypts data of the content or scrambles data of the content for image and speech sound so that the disk ID signal 1402 becomes a decipher key for decrypting the encryption on the optical disk 1101 where the data of the content within the content memory 1407 is recorded. In the third preferred embodiment, a process of encrypting the content 1407 by using the disk ID signal 1402 as a cipher key means the same as the encrypting process. Also, in the third preferred embodiment, encrypting and decrypting are considered as a relationship between a lock and a key so that closing the lock with the key is referred to as encrypting and opening the lock with the key is referred to as decrypting. Accordingly, encrypting and decrypting differ in actual operation from each other; however, the keys for encrypting and for decrypting are the same as each other. The content 1407 is denoted by C, the disk ID signal 1402 is denoted by BCAS, the encrypted content 1409 is denoted by C[BCAS], and the operation for the encrypting process is denoted by*. Accordingly, the following equation can be represented: The content 1409 that is encrypted by the encryption section 1406 is sent to a recording circuit 1411 of the recording and reproducing apparatus 1410 via the interface 1403 and 1404 as well as the network 1405. The recording circuit 1411 digitally modulates the data of the inputted content in a predetermined manner, and records the data of the content onto the optical disk 1101 by modulating the intensity of the laser beam from the optical pickup 1301 corresponding to the digitally modulated data and irradiating the laser beam onto the optical disk 1101. Next, when the above-described content that is encrypted and recorded on the optical disk 1101 is reproduced, a laser beam that is outputted from the optical pickup 1301 irradiates the area where the above-described encrypted content of the user data area 1103 is recorded, and, after the reflected light is photoelectrically converted by the optical pickup 1301, the reproduced signal which has been photoelectrically converted is inputted to the data reproducing section 1412. The data reproducing section 1412 A/D converts the inputted reproduced signal into digital data, and outputs the digital data to the encryption decoder 1413. On the other hand, a laser beam from the optical pickup 1301 is irradiated onto the BCA 1104 of the optical disk 1101, and, after the reflected light is photoelectrically converted by the optical pickup 1301, the reproduced signal which has been photoelectrically converted is inputted to the BCA reproducing circuit 1401. The BCA reproducing circuit 1401 A/D converts the inputted reproducing signal so as to generate the disk ID signal 1402, and then, the disk ID signal 1402 is outputted to the encryption decoder 1413. The encryption decoder 1413 uses the inputted disk ID signal 1402 as a key for decrypting the data of the encrypted content. At this time, when the content is regularly recorded on the optical disk 1101, the key for decrypting the encrypted content that is recorded on the optical disk 1101 is the disk ID signal 1402 of the optical disk 1101, and the disk ID signal 1402 that is outputted from the BCA reproducing circuit 1401 upon reproduction is also the disk ID signal (BCAS) of the optical disk 1101. Accordingly, the content which is either decrypted or descrambled is outputted from the encryption decoder 1413 as an output signal 1414. When the operation for the decoding process is denoted by #, the following equation can be represented: In this case, when the data of the content is image data, the image data such as an MPEG signal is expanded so as to obtain data of an image signal. As described above, the encrypting of the third preferred embodiment has a disk ID as a key, and since only one disk ID exists corresponding to one optical disk, there is an advantageous effect such that the same encrypted content can be recorded only on that optical disk. That is to say, when the above-described content 1407 is attempted to be copied and reproduced onto another optical disk which has another disk ID of ID2 from a regular optical disk which has, for example, a disk ID of ID1, ID2 is outputted as the disk ID signal 1402 from the BCA reproducing circuit 401. However, the encrypted content is encrypted with a disk ID signal of ID1, and therefore, the encrypted content cannot be decoded by the encryption decoder 1413. The encrypting encoder 1408 is not located at a supplying source of the content, and is located on the side of the recording and reproducing apparatus in the network, then it may be formed in a form of an IC card or the like on which the encrypting encoder 1408 is mounted. Also, since the above-mentioned optical disk 1101 is encrypted by using only the disk ID, data can be reproduced with an arbitrary optical disk recording and reproducing apparatus having the BCA reproducing circuit 1401 and the encryption decoder 1413. Fourth Preferred Embodiment Next, an encrypted content recording method of the fourth preferred embodiment according to the present invention will be described with reference to the drawings. FIG. 20 is a block diagram illustrating a configuration of an optical disk recording and reproducing system of a fourth preferred embodiment according to the present invention, which shows an apparatus configuration for recording encrypted content on a recording-type optical disk which is either a rewritable or non-rewritable optical disk having a BCA. In the following description of the fourth preferred embodiment, a description of the same elements that were described with respect to the third preferred embodiment are omitted. Referring to FIG. 20, the optical disk recording and reproducing system according to the fourth preferred embodiment comprises a CATV company apparatus 1501, a key issuing center apparatus 1507, a CATV decoder 1506, an optical disk recording and reproducing apparatus 1514, and a television set 1530. In this case, the CATV company apparatus 1501 comprises a content memory 1502 for storing data of contents such as movie software, a first cipher key memory 1503 for storing a first cipher key, and a first cipher encoder 1504. Also, the key issuing center apparatus 1507 comprises a control section 1507a for controlling the operation of the key issuing center apparatus 1507, a time limiting information memory 1510 for storing time limiting information, and a recording admission code memory 1511 for storing a limiting admission code. In addition, the CATV decoder 1506 comprises a system ID memory 1508 for storing a system ID of the CATV decoder 1506, a first cipher decoder 1513, a second cipher encoder 1516, and a company identification signal memory 1523 that is provided within an IC card 1522. Furthermore, the optical disk recording and reproducing apparatus 1514 comprises a recording circuit 1518, a data reproducing section 1519, a BCA reproducing circuit 1521, a second cipher decoder 1520, and a company identification signal memory 1526 that is provided within an IC card 1524. First of all, the first cipher encoder 1504 of the CATV company apparatus 1501 encrypts the data of the content, such as movie software, that is stored in the content memory 1502 by using a first cipher key that is stored in the first cipher key memory 1503 so as to generate a first encrypted content 1505. Then, the generated first encrypted content 1505 is transmitted to the first cipher decoder 1513 of the CATV decoder 1506 for each user via the network. When the data that is stored in the content memory 1502 of the CATV company apparatus 1501 is denoted by C, the first cipher key stored in the first cipher key memory 1503 is denoted by FK, and the first encrypted content 1505 is denoted by C [FK]. Then, the following equation can be represented: The CATV decoder 1506 transmits, via the network to the key issuing center apparatus 1507,
Based on the system ID of the CATV decoder 1506 and the title code 1509 of the above-mentioned content, the control section 1507a of the key issuing center apparatus 1507 refers to the time limiting information that is stored in the time limiting information memory 1510 and the recording admission code that is stored in the recording admission code memory 1511, and transmits a key (K) 1512 corresponding to these data of the recording admission code and the time limiting code, together with the recording admission code and the time limiting code, via the network to the first cipher decoder 1513 of the CATV decoder 1506. The time limiting information allows the same content to be distinguished from among the cases where the same content is broadcasted a plurality of times at different times. When the first decipher key is denoted by FK, the system ID of the CATV decoder 1506 is denoted by DID, the time limitation information is denoted by TIME, the recording admission code is denoted by COPY, and the title code 1509 of the content is denoted by T. Then, the key (K) satisfies the relationship that is indicated by the following equation: It is determined whether the recording admission code that is stored in the record permission (admission) code memory 1511 is permitted only for watching and listening, or for both of watching and listening, and recording, based on a judgment result when the CATV company apparatus 1501, for example, judges whether or not the broadcast content is a new work or an old work. The first cipher decoder 1513 of the CATV decoder 1506 decrypts the first encrypted content 1505 when the first decipher key (FK), the key (K) 1512, the title code 1509 of the above-mentioned content, the system ID, the record permission code and the time limitation information satisfy the abovementioned relationship, and the present time information outputted from the clock circuit 1527 satisfies the condition of the time limitation information. In this case, when the above-mentioned encrypted content are an image signal, the descrambled image signal is outputted from the first cipher decoder 1513 to the television set 1530, and then, the user can watch an image of the image signal and listen to an audio signal corresponding to the image signal. In this case, the decrypting process of the first cipher decoder 1513 is expressed by the following equation: ##EQU1## When the record permission code permits only watching and listening, the content data can be recorded on the optical disk 1101. However, when both of watching and listening, and recording are permitted, the content data can be recorded on the optical disk 1101. Therefore, this method will be described as follows. The BCA reproducing circuit 1521 of the optical disk recording and reproducing apparatus 1514 reproduces the data of the BCA 1104 of the optical disk 1101 so as to obtain the disk ID signal 1515, and outputs the disk ID signal to the second cipher encoder 1516 of the CATV decoder 1506. The second cipher encoder 1516 of the CATV decoder 1506 encrypts the data of the content outputted from the first cipher decoder 1513 by using the disk ID signal 1515 as the second cipher key so as to generate a second encrypted content 1517, and outputs the generated second encrypted content 1517 to the recording circuit 1518 of the optical disk recording and reproducing apparatus 1514. It is to be noted that the above-mentioned encrypting of the second cipher decoder 1516 is limited to the time when the first encrypted content is decrypted and outputted from the first cipher decoder 1513. The content which is the output signal from the first cipher decoder 1513 is denoted by C, the disk ID signal 1515 which is the second cipher key is denoted by BCAS, and the second encrypted content 1517 is denoted by C [BCAS]. Then, the following equation can be represented: The second encrypted content 1517 that is outputted to the recording circuit 1518 of the optical disk recording and reproducing apparatus 1514 is modulated by using, for example, a well-known 8/16 modulation system to the recording circuit 1518, and then, the modulated signal is recorded in the user data area 1103 on the optical disk 1101 by the optical pickup (not shown). When the above-mentioned content that is encrypted and recorded on the optical disk 1101 is reproduced, the laser beam that is outputted from the optical pickup is irradiated onto an area where the above-mentioned encrypted content is recorded on the optical disk 1101 so that the reflected light enters the optical pickup. The above-mentioned optical pickup photoelectrically converts the entered reflected light into a reproduced electric signal, and then, the reproduced signal which has been photoelectrically converted is outputted to the data reproducing section 1519. The data reproducing section 1519 A/D converts the inputted reproduced signal into a digital reproduced signal, and then, the digital reproduced signal is outputted to the second cipher decoder 1520. On the other hand, a laser beam that is outputted from the optical pickup is irradiated onto the BCA 1104 of the optical disk 1101 so that the reflected light enters the optical pickup. The above-mentioned optical pickup photoelectrically converts the inputted reflected light into a reproduced electric signal, and then, the reproduced signal which has been photoelectrically converted is outputted to the BCA reproducing circuit 1521. The BCA reproducing circuit 1521 generates the disk ID signal 1515 based on the inputted reproduced signal, and the generated disk ID signal is outputted to the second cipher decoder 1520. In response to the disk ID signal 1515, the second cipher decoder 1520 decrypts the reproduced encrypted content outputted from the data reproducing section 1519 by using the inputted disk ID signal 1515 as a key. At that time, in the case where the content is regularly recorded on the optical disk 1101, the key for decrypting the encrypted content that is recorded on the optical disk 1101 is the disk ID of the optical disk 1101, and the disk ID signal 1515 that is outputted from the BCA reproducing circuit 1521 is also the disk ID signal (BOAS) of the optical disk 1101. Therefore, the second cipher decoder 1520 can normally carry out the decrypting process. Accordingly, the data of the content that are decrypted or descrambled are outputted from the second cipher decoder 1520 as an output signal 1525. In this case, the decrypting process of the second cipher decoder 1520 can be expressed in the following equation. When the data content is an image signal, the second cipher decoder 1520 expands, for example, an MPEG signal to reproduce an original image signal, and then, outputs the image signal. The above-mentioned optical disk 1101 is encrypted by using only the disk ID signal (BCAS) 1515, and therefore, it is possible to reproduce content data by an arbitrary optical disk recording and reproducing apparatus comprising a BCA reproducing circuit 1521 and the second cipher decoder 1520. Although the encryption encoders 1504 and 1516 perform encryption and the encryption decoders 1513 and 1520 perform decryption in the above description, encrypting and decrypting may be perfo | ||||||