JP2006085807A - Information recording/reproducing device, information recording/reproducing medium, and host device for information recording/reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To powerfully prevent unauthorized copying by burying a cryptographic key which does not follow a specific rule and is difficult to be decoded. <P>SOLUTION: When a disk related to this invention is to be manufactured, a cryptographic key, which is expressed by the difference in the error rate of the disk's ECC blocks, is added to original data. When the data on the disk are to be read, information of one bit constituting of the cryptographic key is obtained by determining the average value of the error rates of sixteen ECC blocks. The cryptographic key has 8x7=56 bits. However, data (a check sum) of eight bit (1 byte) data for checking are added at the last part of the key to prevent a logical value "0" from being erroneously recognized as a logical value "1" caused by deterioration in the error rate due to scratches and stain. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information recording / reproducing apparatus, an information recording / reproducing medium, and a host device of the information recording / reproducing apparatus, which are configured to prevent unauthorized copying using an error correction function of an information recording / reproducing medium such as an optical disk.

  In recent years, with the spread of audio products such as audio equipment and video equipment, the technology of information recording media for recording digital contents and recording / reproducing apparatuses thereof has rapidly developed. Coupled with this, duplication of digital data as a copyrighted work, especially illegal copying, has become a problem, and copy protection technology for preventing illegal copying has been actively developed. As an example using a recent particularly advanced copy protection technique, there is an example of a DVD video disk device, which uses a complicated encryption technique.

  However, in the conventional information recording / reproducing apparatus and information recording / reproducing medium described in the above background art, for example, a complicated encryption system of a DVD video disk initially functions effectively for illegal copying. However, once the encryption key used for encryption is decrypted, there is a problem that all the content protected by this encryption key is decrypted and freely copied.

  Therefore, in the conventional DVD video disc, as a countermeasure when the encryption key is known, several hundreds of encryption keys are prepared in advance. In this system, it is separated so that it cannot be used as an encryption key.

  However, although these multiple encryption keys are created based on certain private rules that are compatible with the system, once these rules themselves are known, unauthorized copying can still be prevented. There was a problem of disappearing.

  The present invention has been made in view of the above-described conventional problems, and is an information recording / reproducing apparatus capable of powerfully preventing unauthorized copying by embedding an encryption key that does not follow a specific rule and is difficult to decrypt. An object of the present invention is to provide an information recording / reproducing medium and a host device for the information recording / reproducing apparatus.

  In order to solve the above-mentioned problems, an information recording / reproducing apparatus according to the present invention is an information recording / reproducing apparatus having a function of recording / reproducing information with respect to an information recording / reproducing medium. The ECC block is obtained by mixing wrong data into a means for encrypting information using an encryption key and an ECC block which is a normal recording unit of information so as not to cause error correction. The error data mixing means for changing the error rate of the error data, and the error data for one or more ECC blocks constituting the encrypted information in correspondence with the logical value of each bit of the bit string constituting the encryption key The encryption key is embedded in the encrypted information by selecting one of the options of applying or not applying the mixing means Stage and, the information in which the encryption key is the encrypted embedded, there is provided an information recording and reproducing apparatus characterized by comprising a means for recording on said information recording medium.

  Here, the one or more ECC blocks to which the error data mixing means is selectively applied are recorded in a predetermined area on the information recording / reproducing medium.

  Further, the logical value of each bit of the bit string constituting the encryption key is selectively determined based on an error rate of the corresponding one or more ECC blocks or an average value thereof.

  An information recording / reproducing medium according to the present invention is an information recording / reproducing medium in which information is recorded / reproduced by an information recording / reproducing apparatus, and the information to be recorded / reproduced is encrypted using an encryption key. And error data mixing means for changing the error rate of the ECC block by mixing erroneous data to an ECC block which is a normal recording unit of information so as not to cause error correction. Whether to apply the error data mixing means to one or more ECC blocks constituting the encrypted information in correspondence with the logical value of each bit of the bit string constituting the encryption key By selecting any one of the options, the information recording / reproducing apparatus includes means for embedding the encryption key in the encrypted information. There is provided an information recording and reproducing apparatus which is characterized in that those recorded Te.

  Here, the data obtained by selectively applying the error data mixing means to the one or more ECC blocks is recorded in a predetermined area.

  Further, the logical value of each bit of the bit string constituting the encryption key is selectively determined by an error rate of the corresponding one or more ECC blocks or an average value thereof.

  The host apparatus of the information recording / reproducing apparatus according to the present invention is a host apparatus connected to the information recording / reproducing apparatus having a function of recording / reproducing information with respect to the information recording / reproducing medium, The information recording / reproducing medium according to claim 4 loaded in the information recording / reproducing apparatus according to any one of claims 1 to 5, means for determining whether copying is prohibited, and copying is prohibited Means for designating a specific address on the information recording / reproducing medium and sending an instruction for receiving an encryption key embedded from the address to the information recording / reproducing device, if recorded, from the address Information comprising: a means for sending a command for receiving data to the information recording / reproducing apparatus; and a means for decrypting the data using the received encryption key. There is provided a host device for a recording and reproducing apparatus.

  That is, the information recording / reproducing apparatus of the present invention is intentionally erroneous for each ECC block of information to be recorded in the information recording / reproducing apparatus for recording / reproducing information on / from an information recording / reproducing medium having error correction. By mixing data, the error rate for each ECC block is increased to the extent that it cannot be corrected. More specifically, each logical value of the bit string is assigned such that the ECC block whose error rate is changed is “1”, and the ECC block which is not changed is “0” (or vice versa). An encryption key is composed of a bit string having, and the data including the encryption key is recorded on an information recording / reproducing medium so that the encryption key is embedded and hidden in the data, thereby illegally recording information created by unauthorized copying The reproduction medium is characterized in that the encryption key cannot be duplicated.

  In this information recording / reproducing apparatus, an ECC block assigned to one bit constituting an encryption key uses a plurality of continuous ECC blocks in consideration of deterioration of an error rate due to scratches or dirt, and the error rate of the plurality of ECC blocks. It is preferable to determine “1” or “0” based on the average value.

  Further, the information recording / reproducing medium of the present invention has a means for raising the error rate in units of ECC blocks so as not to be uncorrectable by intentionally mixing erroneous data into the information recording / reproducing medium having error correction. Bits are assigned such that the ECC block with the error rate changed is “1”, and the ECC block without the change is “0” (or vice versa), and an encryption key is configured by these bit strings and recorded. .

  In this information recording / reproducing medium, the ECC block allocated to one bit constituting the encryption key uses a plurality of continuous ECC blocks in consideration of deterioration of the error rate due to scratches or dirt, and the error rate of the plurality of ECC blocks. It is preferable to determine (or determine) the logical values “1” and “0” of each bit constituting the encryption key based on the average value.

  The host device of the information recording / reproducing apparatus of the present invention determines whether copying is prohibited for the information recording / reproducing medium loaded in the information recording / reproducing apparatus, and determines that copying is prohibited. In this case, a command for receiving the encryption key embedded in the information recording / reproducing medium from the information recording / reproducing apparatus is transmitted, and the encryption key is received from the information recording / reproducing apparatus as a response. Thereafter, the encrypted data is read from the information recording / reproducing apparatus, and the encrypted data is decrypted using the received encryption key.

  As described above, according to the information recording / reproducing apparatus, information recording / reproducing medium, and host apparatus of the information recording / reproducing apparatus of the present invention, the data to be recorded on the information recording medium is encrypted with the encryption key. Unauthorized copying is prevented by embedding error data that represents the key in the data, but outsiders other than authorized dealers cannot know the distribution of the error data that represents the encryption key. Therefore, there is an effect that it is difficult to copy illegally.

  In addition, it is not easy to know the encryption key embedded in the regular disk from the outside, and since the application data on the unauthorized disk does not contain the encryption key, an unauthorized user can use the copied unauthorized Even if the application data on the disk is successfully read, the application data cannot be used by removing the scramble applied to the application data.

  Even if one encryption key in a certain disk is known to the outside, an alternative encryption key can be arbitrarily embedded regardless of a specific rule. Therefore, there is an effect that it is possible to practically prevent a situation where the unauthorized copy prevention system itself does not function effectively due to the requirement for the formula.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the information recording / reproducing apparatus, information recording / reproducing medium, and host apparatus of the information recording / reproducing apparatus of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of an information recording / reproducing system including an information recording / reproducing apparatus and its host device according to an embodiment of the present invention.
In the figure, an information recording / reproducing apparatus 1 of this embodiment includes a recording / reproducing head 12 for recording / reproducing data on / from an optical disc 2 (recording medium described later) which is an information recording / reproducing medium of this embodiment. The servo control unit 13 for performing servo control of the optical disc 2, the data modulation / demodulation unit 14 for recording / reproducing data on the optical disc 2 in cooperation with the servo control unit 13, and the recording for storing recording / reproduction data A reproduction buffer 15, an ECC memory 16 which is a work area of an ECC circuit 17 (described later), an ECC circuit 17 for adding an error correction code, detecting and correcting an error, and controlling the operation of the entire apparatus. System control microcomputer 18, and instructions such as read / write and command execution results from the host device 10 which is the host device of this embodiment It is configured with to status, and the host I / F control unit 19 for transmitting and receiving other data.

The optical disc 2 is a removable optical disc medium.
Since the host device 10 according to the present embodiment can be configured by a known computer system, its configuration diagram is omitted.

The operation of the information recording / reproducing apparatus and its host apparatus according to this embodiment will be described below.
As shown in FIG. 1, the information recording / reproducing apparatus and its host device according to the present embodiment use a removable optical disk 2 as the information recording / reproducing medium according to the present embodiment. Hereinafter, in the optical disc 2 according to the present embodiment, the minimum unit of data including an error correction code is referred to as an ECC block.

Each ECC block is assigned an address that can be uniquely identified on the disk.
A read / write command from the host device 10 designates a start position on the optical disc 2 where reading / writing is desired and a size of data where reading / writing is desired.

  The recording / reproducing buffer 5 is a RAM for temporarily storing data, and absorbs the difference between the recording / reproducing speed of the optical disc 2 and the data transfer speed with the host device 10. Further, the system control microcomputer 8 instructs the ECC circuit 7 to add an error correction code when recording data on the disk, and to the ECC circuit 7 when reproducing the data on the disk. It indicates that error correction using the error correction code should be performed.

Next, the structure of the information recording / reproducing medium according to the present embodiment will be described.
FIG. 2 is a schematic diagram showing the structure of the information recording / reproducing medium according to the present embodiment.
The optical disc 2 that is the information recording / reproducing medium according to the present embodiment is necessary for recording / reproduction, such as a reference value for obtaining an optimum laser power output for recording on the innermost circumferential area. A non-rewritable area in which various information is stored is provided (hereinafter referred to as “HFM area”).

The outer circumferential area is provided with an area for finely adjusting the output value of the laser power by actually trying to record / reproduce the disk with the reference laser power written in the HFM area (hereinafter referred to as “the laser power”). This is referred to as an “OPC area”).
Further, the outer circumferential area is a data area, and a plurality of ECC blocks for recording and reproducing data are provided in a spiral shape. An address is set for each ECC block. This address increases from the inner periphery toward the outer periphery. For example, addresses from 020000h to 17FFFFh are set in hexadecimal.

  Management information for managing the application is recorded in the data area. This is usually recorded near the inner periphery of the disc, but in the present invention, it is not fixed at a specific address.

Next, a method for reproducing the encryption key embedded in the information recording / reproducing medium according to the present embodiment will be described (Note that the procedure for creating the information recording / reproducing medium according to the present embodiment in which the encryption key is embedded is described). Will be described later).
In the information recording / reproducing apparatus according to the present embodiment, the error rate of one ECC block on the optical disc 2 as an information recording / reproducing medium or the average value of the error rates of a plurality of ECC blocks is used. Creating a logical value. Hereinafter, a method for decrypting an encryption key for extracting an encryption key from a record on a disc during disc reproduction will be described in more detail.

FIG. 3 is an explanatory diagram showing the error rate when a normal disk with no encryption key embedded is reproduced.
As shown in the figure, unless the disk is scratched or soiled, the error rate is normally kept much lower than the limit value at which correction is impossible (the uncorrectable level in FIG. 3).

  FIG. 4 is an explanatory diagram showing the error rate when a normal disk with no encryption key embedded is reproduced. FIG. 4 shows a situation when error data is intentionally mixed in a certain ECC block to deteriorate the error rate. Since error data is intentionally mixed in the ECC block shown in the figure, the error rate is higher than that shown in FIG.

The error rate state as shown in FIG. 3 is logical value “0”, and the error rate state as shown in FIG. 4 is logical value “1”, corresponding to 1-bit information (logical value) of the encryption key. Let
In this case, one ECC block may correspond to one bit of the encryption key. However, in order to further improve the reliability, a plurality of ECC blocks are grouped together, and an average value thereof is obtained to determine the 1-bit information of the encryption key. May be used for decision.

FIG. 5 is an explanatory diagram showing a specific example of a method for extracting an encryption key from ECC block data recorded on a disc.
This figure shows the case of a disk in which the encryption key is embedded from the address 070000h. The 1-bit information constituting the encryption key is obtained by determining the average error rate of 16 ECC blocks. ing. In the example shown in FIG. 5, the encryption key is 8 × 7 = 56 bits, but the error rate deteriorates due to scratches or dirt, and the logical value “0” is erroneously recognized as the logical value “1”. In order to prevent this, 8-bit (1 byte) data for checking is added at the end.

In this example, the check data is the lower 1 byte of the total value of the data byte values for the encryption key body. In FIG. 5, this is shown as “checksum”.
The actual data check method is to “read” the read command and read the embedded encryption key while adding the byte values of the data one after another. This is confirmed by determining whether or not the checksum values read out at the same time match.

If the determination result indicates a mismatch, it is understood that the encryption key has not been read correctly, and the encryption key is discarded. Since the encryption key is continuously embedded in a specific location a plurality of times, if it does not match, the subsequent encryption key is read.
Even if the checksum confirmation is OK for any one encryption key, if the check result matches by checking the subsequent encryption key as a precaution, further reliability can be obtained. Will rise.

  Note that the check data may be other codes such as a CRC code instead of the checksum as shown in the example of FIG. The checksum only knows whether or not there is a reading error, but if it is a CRC code or the like, the error can be corrected and the reliability is further improved.

Next, a method for reproducing data recorded on the disc will be described.
The information recording / reproducing apparatus 1 includes a command (hereinafter referred to as an encryption key request command) for taking out the embedded encryption key and transferring it to the host device 10.
On the other hand, the host device 10 connected to the disc recording / reproducing apparatus 1 is designated by instructing the information recording / reproducing apparatus with this encryption key request command separately from the normal read command for reading data. The encryption key embedded in the ECC block from the specified address can be read out.

The operation of the encryption key request command will be described below.
The encryption key request command reproduces an ECC block starting from a designated address, and obtains an encryption key by converting it into a bit string by the above-described decryption method based on the error rate.
At this time, if the checksum added at the end of the data is confirmed and it is OK, the obtained encryption key and the normal status are returned to the host device 10. If this checksum is abnormal, as described above, the reproduction and decryption of the encryption key of the next ECC block is continued.

In this check of the encryption key using the checksum, for example, if the checksum is not OK even after reading 10 times, an error status can be returned to the host device.
The above is the operation of the encryption key request command.

  The operation of the information recording / reproducing system including the information recording / reproducing apparatus according to the embodiment of the present invention and its host device will be described below.

  Now, there is a regular disc (here, disc 2) on which application data (including programs to be protected and digital contents) is recorded. This application data is as described above in order to prevent unauthorized copying. It is assumed that it has been encrypted by scrambling. In order to decrypt and decrypt (scramble) this scramble, a corresponding encryption key is required. As described above, this encryption key is embedded at a specific address on the disk by the method described above.

  The user operates the host device 10 to start using the application data after loading the disc 2 in the disc device 1 connected to the host device 10, and issues a read command to the information recording / reproducing device 1. As a result, the information recording / reproducing apparatus 1 first reads the most basic management information recorded on the disc 2 and refers to this management information to optimally set the laser power designation and the like. Next, the management information for the application on this disk is read into the host device 10.

  In the management information for this application, information on whether or not the disc 2 is copy-protected, and the address of the ECC block in which the encryption key for releasing the scramble is embedded in the case of copy prohibition are recorded. ing.

When the host apparatus 10 determines that the disk 2 is a copy-inhibited disk by the above reading, the host apparatus 10 commands (sends) an encryption key request command using the address where the encryption key is embedded as a parameter to the information recording / reproducing apparatus 1. To do.
As a response to this command, the host device 10 that has received the encryption key from the information recording / reproducing device 1 uses the encryption key to decrypt and use the scrambled application data read by the normal read command thereafter. To do.

Even if the information recording / reproducing apparatus 1 is connected to another host device to extract and copy the application data, the application data is scrambled so that the unauthorized user can use it. I can't.
In order to cancel this scramble, the encryption key described above is required. Even if the address where the encryption key is embedded is known to the unauthorized user by any method, Data read from the recording / reproducing device 1 to the host device cannot be decrypted as meaningful data (ie, an encryption key) by a conventional decryption method using an algorithm.

  Even if it is known that the error rate is a key involved in the decryption, the error rate measurement process necessary for actually extracting the encryption key is performed by the ECC process in the information recording / reproducing apparatus 1. This is a closed process performed in cooperation with the circuit and the system control microcomputer. Therefore, it is very difficult for an unauthorized user to know this encryption key.

Next, the operation when illegal copying is performed will be described.
Since the regular disk prohibited from copying according to the present invention (here, disk 2) is encrypted by scrambling the data, the data cannot be decrypted without the encryption key.

  When an unauthorized user attempts to duplicate an application on a regular disk according to the present invention on another disk as it is, this duplication is possible through the host device 10, but up to the encryption key. Cannot be deciphered, so this unauthorized user cannot use the scrambled data.

  In addition, since the data obtained by the unauthorized user via the host device 10 and the information recording / reproducing device 1 is error-corrected by the recording / reproducing device 1, not the application data on the legitimate disc, the unauthorized user Cannot know the error rate or the position where the error data is mixed. Therefore, the same error data cannot be mixed in the duplication destination disk at the same position as the regular disk (that is, an unauthorized user cannot duplicate the encryption key).

  Therefore, even if the copied non-regular disk is loaded in the information recording / reproducing apparatus 1 and the host apparatus 10 sends an encryption key request command to the disk, the ECC block at the designated address has an encryption key. In this state, the information recording / reproducing apparatus 1 returns an error status to the host apparatus 10, so that the host apparatus 10 descrambles the data recorded on the irregular disk. It cannot be done.

  Note that the application referred to here includes video information such as moving images. The configuration of the information recording / reproducing system in this case is such that the information recording / reproducing apparatus 1 and the host apparatus 10 are housed in a single casing and connected inside the casing, and a moving picture is reproduced outside the casing. -A configuration example with a stop button is possible.

  As a usage form of this information recording / reproducing system, the user operates the reproduction / stop button, an external remote controller, etc., so that the host device 10 inside the case allows information recording / reproduction inside the case. A mode is possible in which the apparatus 1 is instructed to record and reproduce data, and thereby recording and reproduction of a moving image is started. That is, the information recording / reproducing system in this case can be considered as a kind of moving image player or moving image recorder when viewed from the user.

Next, a procedure for producing an information recording / reproducing medium (manufacturing process etc.) according to the embodiment of the present invention will be described.
In the case of a read-only disc, mass production is usually performed by creating and pressing a master disc in a disc production factory, but the information recording / reproducing medium including the encryption key according to the present embodiment is However, the machine is not necessarily limited to a machine in a disc production factory. For example, a terminal device for general users is used as long as the functions of the information recording / reproducing apparatus 1 and the host apparatus 10 according to the present embodiment are provided. It is also possible to create it.

  In the following, a case where an information recording / reproducing medium is created using a machine in a disc production factory will be described. However, a terminal for general users having the functions of the information recording / reproducing apparatus 1 and the host apparatus 10 according to the present embodiment. The procedure for creating an information recording / reproducing medium using the same is the same as this creating procedure.

  The encryption key of the information recording / reproducing medium according to the present embodiment is embedded by manipulating original data from a designated address by a machine that creates a master disk. As the embedding operation, first, an encryption process is performed in which original data is scrambled with an encryption key. Any encryption method can be used as the encryption method.

Next, the machine that creates the master creates data in which the encryption key is embedded in the original data and records it on the master.
This embedded data is normal data of an ECC block indicating a logical value of “0” corresponding to each bit of the encryption key used when the master creating machine scrambles the data (having a normal error rate). Data, that is, data to which error data mixing means is not applied), or ECC block data indicating logical value “1” (data whose error rate has been intentionally deteriorated, ie, applying error data mixing means) Data). However, the normal data of the ECC block indicating the logical value “0” is already existing as data immediately after being modulated / demodulated by the data modulation / demodulation unit 14, and thus does not need to be created specially. . At the same time, the address on the master in which the encryption key is embedded is recorded in the application management information.

  On the other hand, when the information recording / reproducing medium according to the present embodiment is created by a general information recording / reproducing apparatus having no function of the information recording / reproducing apparatus 1 or the host device 10 according to the present embodiment, the encryption key Therefore, the information recording / reproducing medium according to the present embodiment cannot be created as it is. Therefore, the general information recording / reproducing apparatus is created by connecting a device to which a function capable of embedding an encryption key is added. This apparatus is an apparatus for an authorized manufacturer that manufactures the information recording / reproducing medium according to the present embodiment, and is not available to general users.

  When the conventional data is recorded by the apparatus for a regular manufacturer, this apparatus adds an error correction code to a normal ECC block and then records it on the disk as it is. When it is necessary to embed an encryption key in an ECC block from a specific address as in the information recording / reproducing medium according to the above embodiment, the data modulation / demodulation unit 14 immediately after adding the data error correction code immediately before recording on the disk It is assumed that the above-described operation is added to the original data held. That is, the original data is modified and recorded so as to intentionally deteriorate the error rate of the ECC block corresponding to the logical value “1” of the encryption key. Also in this case, the address in which the encryption key is embedded is recorded in the application management information.

  Incidentally, as described above, the reason why error data is mixed with the original data after the error correction code is added is that even if error data is mixed before the error correction code is added, such a mixing is made. Since the data modulation / demodulation unit 14 adds an error correction code to the error data, even if the error correction code is reproduced, only the error data mixed with the error data is correctly reproduced, and the error rate is affected. Because you can't.

1 is a configuration diagram showing an overall configuration of an information recording / reproducing system including an information recording / reproducing apparatus according to an embodiment of the present invention and its host device. It is a schematic diagram which shows the structure of the information recording / reproducing medium based on this Embodiment. It is explanatory drawing which showed the mode of the error rate at the time of reproducing | regenerating the normal disk which is not embedded with an encryption key. It is explanatory drawing which showed the mode of the error rate at the time of reproducing | regenerating the normal disk which is not embedded with an encryption key. It is explanatory drawing which showed the specific example of the method of taking out an encryption key from the data of the ECC block recorded on the disc.

Explanation of symbols

1. Information recording / reproducing apparatus (information recording / reproducing apparatus according to the present invention)
2. Information recording / reproducing medium (information recording / reproducing medium according to the present invention)
10. Host device (host device of information recording / reproducing device according to the present invention)
12 recording / reproducing head 13 servo control unit 14 data modulation / demodulation unit 15 recording / reproducing buffer 16 ECC memory 17 ECC circuit 18 system control microcomputer 19 host I / F control unit

Claims (7)

In an information recording / reproducing apparatus having a function of recording / reproducing information with respect to an information recording / reproducing medium,
Means for encrypting the information recorded on the information recording / reproducing medium using an encryption key;
Error data mixing means for changing the error rate of the ECC block by mixing erroneous data to the ECC block, which is a normal recording unit of information, to the extent that the error correction cannot be performed;
Whether the error data mixing means is applied to one or more ECC blocks constituting the encrypted information in correspondence with the logical value of each bit of the bit string constituting the encryption key, or not applied Means for embedding the encryption key in the encrypted information by selecting one of the options;
Means for recording the encrypted information embedded with the encryption key on the information recording / reproducing medium;
An information recording / reproducing apparatus comprising:   2. The information recording / reproducing apparatus according to claim 1, wherein the one or more ECC blocks to which the error data mixing unit is selectively applied are recorded in a predetermined area on the information recording / reproducing medium.   3. The logical value of each bit of the bit string constituting the encryption key is selectively determined based on an error rate of the corresponding one or more ECC blocks or an average value thereof. Information recording / reproducing apparatus. An information recording / reproducing medium on which information is recorded / reproduced by an information recording / reproducing apparatus,
The information to be recorded and reproduced is
Means for encrypting the information using an encryption key;
Error data mixing means for changing the error rate of the ECC block by mixing erroneous data to the ECC block, which is a normal recording unit of information, to the extent that the error correction cannot be performed;
Whether the error data mixing means is applied to one or more ECC blocks constituting the encrypted information in correspondence with the logical value of each bit of the bit string constituting the encryption key, or not applied Means for embedding the encryption key in the encrypted information by selecting one of the options;
An information recording / reproducing medium recorded by the information recording / reproducing apparatus comprising:   5. The information recording / reproducing medium according to claim 4, wherein data obtained by selectively applying the error data mixing means to the one or more ECC blocks is recorded in a predetermined area.   5. The logical value of each bit of the bit string constituting the encryption key is selectively determined based on an error rate of the corresponding one or more ECC blocks or an average value thereof. Item 6. The information recording / reproducing medium according to Item 5. A host device connected to an information recording / reproducing apparatus having a function of recording / reproducing information with respect to an information recording / reproducing medium,
Means for judging whether copying is prohibited for the information recording / reproducing medium according to claim 4 loaded in the information recording / reproducing apparatus according to any one of claims 1 to 3;
Means for designating a specific address on the information recording / reproducing medium and sending a command for receiving an encryption key embedded from the address to the information recording / reproducing apparatus when it is determined that copying is prohibited; ,
Means for sending a command for receiving data recorded from the address to the information recording / reproducing apparatus;
Means for decrypting the data using the received encryption key;
A host device for an information recording / reproducing apparatus.

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