JPH07182766A - Digital information transmitting system - Google Patents

Abstract

PURPOSE:To record secret information whose copying is impossible on a recording medium and to prevent an authorized copying by using them. CONSTITUTION:Two kinds of specific pits are recorded at specific positions on an optical disk 2. The reflected light quantity of the first kind of specific pits is made to be a level being just higher than the intermediate level of the case pits are present and of the case pits are not present and the reflected light quantity of the second kind of specific pits is made to be a level being just lower than the intermediate level. An optical disk device reads in specific positions plural times and decides secret information by performing the majority decision of binary information. The certification of an authorized optical disk is performed by using the secret information. Thus, since a new hardware is not required to be added to a conventional optical disk drive, this system is effective even to the optical disk copying device of a type performing copyings at every bit and whether a disk is of a true or not can be surely judged and an effect affecting to the production process of the optical disk is made small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting digital information via a communication path or recording digital information on a recording medium, and particularly to secretly transmitting or specifying digital information only to a specific person. The present invention relates to a method of secretly recording information so that only the person who reads it can read it, or authenticating whether the digital information transmitted or recorded in this way is authentic. The present invention also relates to a digital information copy protection method for protecting digital information being transmitted or recorded from unauthorized copying.

[0002]

2. Description of the Related Art In a digital transmission system for transmitting digital information through a communication path, a converter outputs the digital information on the communication path at each time corresponding to one of m signal points. On the communication channel, the signal point is transmitted while being disturbed by noise, and the inverse converter inputs the signal point of the output of the communication channel at each time described above and makes it the closest one of the m signal points. The digital information is restored by making them correspond.

Further, a digital recording system in which digital information is recorded as a signal on a recording medium and the digital information is reproduced from this is also widespread. In this digital recording system, the converter records digital information at each position on the recording medium in correspondence with one of the m signal points, and the inverse converter causes noise at the time of reading the recording medium at each position. The digital information is restored by inputting the signal point on the recording medium which has been disturbed and making it correspond to the closest one of the m signal points.

An optical disc is a typical application example of this digital recording system. Optical discs are widely used as external storage devices for computers and the like, which have advantages such as small size, low price, large capacity, and high-speed access. Then, a program executed by a computer or the like and data (hereinafter referred to as software) referred to by the program are stored as digital information on the optical disc, and it is actively sold. This software was very laborious to create, and the creators should, of course, be paid a fair price. If the software recorded on the optical disc as digital information is taken out to the outside by a copying apparatus and copied onto another optical disc, and the copied optical disc is sold without permission to the creator, it is created. The person will not be able to obtain the consideration that should be received, which causes a big problem. In addition, if the creator considers this fact and sets the price of digital information at a high price and sells it, the user of the digital information will pay a higher price than the original price, which is also a big problem. Become.

In order to solve the above problems, various copy protection methods for recording media have been proposed.

One type of copy protection method for a recording medium that has been conventionally proposed is to encrypt recorded digital information and distribute the information for decrypting the encrypted information to the original information by another means which is difficult to copy. It is a thing. Even if this kind of digital information is copied, the copy is substantially prevented unless there is information for decrypting the code to the original information.

Another class of conventionally proposed disc copy protection methods is that when recording digital information on a disc based on a specific standard, special recording that does not comply with the standard or is not defined. By using this method and keeping the special recording method secret, only a device or software that knows the special recording method can reproduce all digital information on the disc, and a device that does not know it (copy device) The digital information of some parts cannot be reproduced, and therefore a complete copy cannot be made. For example, in the copy protection method described in Japanese Patent Laid-Open No. 1-256070, one track has 26 sectors and the total number of tracks is 74 in the Japanese Industrial Standard regarding the format of a flexible disk. The existence of the 75th track on the disk or the existence of the 75th track on the disk is intended to prove the authenticity of the disk by the existence of the information recording in the sector or track out of these standards.

[0008]

However, the former method has a problem that another means other than the recording medium is required, for example, a semiconductor chip, and a connecting means for that is newly required.

In the latter method, a copying device possessed by an illegal person who attempts to illegally copy a disc copies only information within a standard (ie, 26 sectors per track, 74 tracks per disc).
It is based on assumptions that differ from reality. However, in reality, not only a copy of information within the standard but also a copy device for copying every bit information existing on the disc is available on the market. It is obvious that the latter copy protection system is useless for such a so-called "bit copy machine".

Accordingly, one object of the present invention is to solve the above-mentioned problems that the conventional optical disk copy protection methods have. That is, the first point is that it is not necessary to add new hardware to the conventional optical disk drive or only a slight change is required, and it can be realized only by changing the software of the optical disk device or the device that drives it. The second point is that it is also effective for an optical disk copying apparatus of the type that makes bit-by-bit copying, and true / false judgments can be made with certainty, and the influence on the optical disk manufacturing process is minimal.

Another object of the present invention is not limited to realizing the above-mentioned optical disc copy prevention method, but the digital information recorded on a general recording medium or the digital information transmitted via a communication path is authentic. An object of the present invention is to provide a method of authenticating digital information, which can determine whether it is real or not.

Another object of the present invention is to transmit secret information via a communication path and to record secret information on a recording medium.

[0013]

In order to achieve the above object, the digital information transmission system according to the first aspect is such that the digital information is associated with one of the m signal points at each time other than a specific time. And outputs it on the communication path at a specific plurality of times, and outputs one of k signal points other than the above m signal points on the communication path, and the above-mentioned while being disturbed by noise. A communication path for transmitting signal points,
At each time other than the specific time, the signal point of the output of the communication path is input, and this is made to correspond to the closest one of the m signal points, and at the specific time, it is output from the communication path. One of the k signal points is processed according to the frequency distribution of the m signal points, which is the processing result for each specific time, by performing the process of matching the signal point to the closest one of the m signal points. And an inverse transformer that restores the digital information by determining

According to a second aspect of the present invention, in the secret transmission method of digital information, the processing at the specific plurality of times, the specific k signal points, and the processing related to the specific signal points are kept secret except in a specific range. Thus, one of the k specific signal points is secretly transmitted outside the specific range.

According to a third aspect of the present invention, there is provided a digital information authenticating method on a communication path, wherein at each time other than a specific time, digital information is output on the communication path in correspondence with one of the m signal points, and a plurality of specific information is output. A converter that outputs one of k signal points other than the above m signal points at the time of
A communication path that transmits the above signal points while being disturbed by noise, and a signal point at the output of the communication path at each time other than the above specific time are input, and these are input to the nearest one of the m signal points. And an inverse converter that performs a process of associating the k signal points output from the communication path with the closest one of the m signal points at the specific time, and processing for each specific time. If the resulting frequency distribution of the m signal points shows a predetermined distribution, the converter connected to the communication path is regarded as authentic, or the digital information transmitted via this communication path is regarded as authentic. It has an authentication means to judge that it is authentic.

According to another aspect of the digital information recording system of the present invention, digital information is recorded at each position other than the specific position on the recording medium in correspondence with one of the m signal points, and the position on the specific recording medium is recorded. , A converter that outputs one of k signal points other than the above m signal points, a reader that reads a signal point on a recording medium as a signal point containing noise, and a position other than the specific position At each recording medium position, the output of the reader is made to correspond to the closest one of the m signal points, and at the specific recording medium position, the signal point output from the reader is converted to the m signal points. The process corresponding to the closest one of the points is performed plural times, and the frequency distribution of the above-mentioned m signal points, which is the processing result for each specific recording medium position and one specific position, is performed. Determining the one of said k-number of signal points, an inverse converter for reproducing digital information corresponding thereto.

According to a fifth aspect of the present invention, in the secret recording method for digital information, the existence of the specific k signal points, the position on the specific recording medium, and the processing relating to the specific signal point are secret except for a specific range. By doing so, one of the k specific signal points is secretly recorded in a region other than the specific range.

According to a sixth aspect of the present invention, in the secret recording method for digital information, the converter is one of k signal points other than the m signal points at a plurality of positions other than the position of the specific recording medium. It is configured to output corresponding to one.

According to a seventh aspect of the present invention, there is provided a digital information authentication method on a recording medium, wherein digital information is output at each position other than a specific recording position on the recording medium in correspondence with one of m signal points, and the digital information is specified. A converter that outputs one of k signal points other than the m signal points at a position on the recording medium, a reader that reads the signal point on the recording medium as a signal point containing noise, At each position other than the specific position, the output of the reader is made to correspond to the closest one of the m signal points, and at the position on the specific recording medium, the signal point output from the recording medium is set to m. Inverter that performs processing corresponding to the closest one of the signal points, and that the frequency distribution of the above-mentioned m signal points, which is the processing result for each specific time, shows a predetermined distribution. An authentication means for determining digital information on the recording medium or the recording medium as authentic.

In the digital information recording method on the recording medium according to the present invention, the converter outputs 1-bit input digital information from the two signal points S0 and S1 at a position other than the position on the specific recording medium. Each signal point is recorded on the recording medium in correspondence with two levels V0 and V1. When the other 1-bit input digital information is 0 at a specific recording medium position, the level V0 is recorded.
When the input digital information is 1, a specific signal point S1 having a level V11 is associated with a specific signal point S00 having a 0.
1, where V0 <V00 <V11 <V1 and the levels of V00 and V11 are set to cause an error with a certain probability in the binary determination due to noise applied on the recording medium. The inverse converter performs processing for associating the input signal point with S0 or S1 at positions other than the specific position on the recording medium, and makes the input signal point S0 at the specific recording medium position. Or S1 is repeated a plurality of times, and the secret information is recorded by reproducing the digital information corresponding to the larger one of S0 and S1 which is the processing result for each specific recording medium position and one specific position. Configured to do.

In the digital information authenticating method on the recording medium according to the ninth aspect, the converter outputs the 1-bit digital information to one of the two signal points S0 and S1 at a position other than the position on the specific recording medium. Each signal point is made to correspond to two levels V0 and V1, and an intermediate level V2 of these signal points at a specific recording medium position.
Output a specific signal point corresponding to, and the inverse converter outputs the input signal point S at a position other than a specific position on the recording medium.
A process corresponding to the closer one of 0 and S1 is performed so that the input signal point is S0 or S at a specific position on the recording medium.
Repeat the process of matching to the closest one of the multiple times,
As a result, the decoded S0 and S1 are about half each, and it is determined that a specific signal point exists. At this time, the authentication unit determines that the recording medium or the digital information on the recording medium is authentic. Is configured.

According to a tenth aspect of the present invention, there is provided a digital information recording method on a recording medium, wherein the digital recording medium is an optical disc, and the converter has a 1-bit digital information of 0 at a position other than a specific position on the optical disc. The pit having the maximum reflectance as the signal point S0 at this time and the pit having the minimum reflectance as the signal point S1 at 1 are recorded on the optical disc. When the bit digital information is 0, a specific pit whose reflectance is slightly higher than the intermediate level between the maximum level and the minimum level is set. When the digital information is 1, the reflectance is slightly lower than the intermediate level. It records a specific level pit, and the inverse converter is located at a position other than the specific position on the optical disc. Performs the process of associating the input signal point with S0 or S1, and repeats the process of associating the input signal point with S0 or S1 a plurality of times at a specific optical disk position. Each specific optical disk position and one specific position It is configured to determine which one of S0 and S1 which is the plurality of processing results for the larger one.

In the digital information authenticating method on the recording medium according to the eleventh aspect of the present invention, as digital recording medium, 1-bit digital information is made to correspond to a pit having a maximum reflectance and a pit having a minimum reflectance. An optical disc to be recorded, the converter records specific pits such that the reflectance is at an intermediate level between the maximum level and the minimum level at a predetermined position on the optical disc, and the inverse converter corresponds to the specific pits. Read-out processing is performed a plurality of times to determine whether the distribution of the read binary data matches the distribution determined by the specific pit.

According to a twelfth aspect of the digital information authenticating method on the recording medium, the reflectance of the specific pit is about half of the maximum level and the minimum level, and the signal distribution corresponding to the specific pit is 0 or 1. Are configured to be about half each.

According to a thirteenth aspect of the present invention, in the digital information recording method on the recording medium and the digital information authentication method on the recording medium, when the specific pits are arranged on the optical disk, half of the specific pits in the error correction frame are arranged. Is arranged so as to have an error correction capability or more, and the binary data after the error correction processing is targeted for processing.

According to a fourteenth aspect of the present invention, there is provided a digital information recording method on a recording medium and a digital information authentication method on a recording medium, wherein when arranging the specific pits on an optical disk, half of the number of specific pits in an error correction frame is set. Are arranged so that the error correction capacity is less than or equal to the error correction capacity, and the binary data before the error correction processing is processed.

The digital information recording method and the digital information authentication method on the recording medium according to the fifteenth aspect are configured to apply a small amount of noise to the reference voltage in the binarization processing of the specific pits.

According to a sixteenth aspect of the present invention, there is provided a digital information recording method on a recording medium and a digital information authenticating method on the recording medium, wherein the specific pit has a reflectance changing at a leading end or a trailing end.

In the digital information recording method on the recording medium and the digital information authentication method on the recording medium according to the seventeenth aspect, the change of the reflectance of the specific pit is the change of the height of the pit or the reflection characteristic of the reflection film. It is configured to occur by the change of.

The copy protection method for a recording medium according to claim 18 determines whether the recording medium is an authentic one or an illegally copied one, and the recording according to claim 5, 6, 8 or 10. It is configured to be performed by a digital information recording method on a medium.

According to a nineteenth aspect of the present invention, there is provided a method for preventing a copy of a recording medium, which comprises determining whether the optical disc is a genuine one or an illegally copied one.
It is configured to perform the digital information authentication method on the recording medium described.

[0032]

In the digital information transmission system according to the first aspect of the present invention, the converter outputs the digital information on the communication path in correspondence with one of the m signal points at each time other than the specific time, and a plurality of specific information are transmitted. At time, one of k signal points other than the above m signal points is output on the communication path, and the inverse converter inputs the signal point of the output of the communication path at any time and outputs it. A process corresponding to the closest one of the m signal points is performed, and at a specific time, the frequency distribution of the m signal points, which is the processing result for each specific time, is used to calculate the frequency of the k signal points. The digital information can be restored by determining one.

According to the secret transmission method of digital information of claim 2, one of the k specific signal points can be secretly transmitted except for a specific range.

In the digital information authenticating method on the communication path according to claim 3, the converter outputs the digital information on the communication path in correspondence with one of the m signal points at each time other than the specific time, and specifies the digital information. At a plurality of times, one of k signal points other than the above m signal points is output, and the inverse converter inputs the signal point at the output of the communication path at any time and outputs it. Corresponding to the closest one of the m signal points, and at the above-mentioned specific time, the signal point output from the communication path is caused to correspond to the closest one of the m signal points. When the frequency distribution of the above-mentioned m signal points, which is the processing result with respect to time, shows a predetermined distribution, the converter connected to the communication path is regarded as authentic or transmitted through this communication path. Digital information authentic It can be determined that.

According to a fourth aspect of the present invention, in the digital information recording system, the converter records the digital information at each position other than the specific position on the recording medium in correspondence with one of the m signal points, and the specific recording medium. At the upper position, one of k signal points other than the above m signal points is output, and the inverse converter outputs the output of the reader at any recording medium position among the m signal points. On each specific recording medium, a process is performed a plurality of times so that the signal point output from the reader is made to correspond to the closest one among the m signal points at the specific recording medium position. Determining one of the k signal points from the position and the frequency distribution of the m signal points, which is the processing result for one specific position, and reproducing the digital information corresponding thereto. Can.

According to the secret recording method of digital information of claim 5, one of the k specific signal points can be secretly recorded except in a specific range.

According to the secret recording method of digital information of claim 6, the position on the recording medium in which the specific signal point is recorded can be kept secret.

In the digital information authenticating method on the recording medium according to the seventh aspect, the converter outputs the digital information at each position other than the specific recording position on the recording medium in association with one of the m signal points. , Output one of k signal points other than the above-mentioned m signal points at a specific recording medium position, and the inverse converter outputs the output of the reader at the m number of points at any recording medium position. Of the signal points output from the recording medium at the position on the specific recording medium corresponding to the closest one of the above signal points, and the authentication is performed. The means is capable of authenticating the recording medium or the digital information on the recording medium by showing a predetermined frequency distribution of the m signal points, which is a processing result for each specific time. It can be determined that.

In the digital information recording method on the recording medium according to the eighth aspect, the converter is 2 due to noise applied on the recording medium corresponding to the secret second digital information.
At the time of value judgment, recording is performed corresponding to a signal point of a level set so as to cause an error with a certain probability, and the inverse converter determines whether the input signal point is S0 or not at a specific recording medium position on the recording medium. By repeating the process corresponding to S1 a plurality of times, the secret information is recorded by reproducing the digital information corresponding to the larger one of S0 and S1 which is the processing result for the position on each specific recording medium and one specific position. be able to.

In the digital information authenticating method on the recording medium of claim 9, the converter outputs a specific signal point corresponding to the intermediate level V2 at a position on the specific recording medium, and the inverse converter outputs the specific recording medium. At the upper position, the process of associating the input signal point with the closer one of S0 and S1 is repeated a plurality of times. As a result, the decoded S0 and S1 are about half each, so that the presence of a specific signal point is confirmed. The authentication means can judge that the recording medium or the digital information on the recording medium is authentic at this time.

According to a tenth aspect of the present invention, in the digital information recording method on the recording medium, the converter is secret at the position on the specific optical disc. When the second digital information is 0, the reflectance is between the maximum level and the minimum level. A specific pit whose level is slightly higher than the level is recorded, and when the digital information is 1, a specific pit whose reflectance is slightly lower than the intermediate level is recorded. At the position on the optical disc, the secret information can be recorded by repeating the process of associating the input signal point with S0 or S1 a plurality of times and determining the larger one of the process results S0 or S1.

In the digital information authenticating method on the recording medium according to the eleventh aspect, the converter records specific pits such that the reflectance is an intermediate level between the maximum level and the minimum level at a predetermined position on the optical disk. Yes, the inverse converter can authenticate the genuine optical disk by performing reading processing for the specific pits a plurality of times and determining whether the distribution of the read binary data matches the distribution determined by the specific pit. .

According to a twelfth aspect of the digital information authenticating method on the recording medium, the reflectance of the specific pit is about half of the maximum level and the minimum level, and the signal distribution corresponding to the specific pit is 0 or 1. It is possible to authenticate a genuine optical disk by being about half each.

In the digital information recording method on the recording medium and the digital information authentication method on the recording medium according to the thirteenth and the fourteenth aspects, secret information and authentication information can be recorded in a portion of the optical disc which is subjected to error correction. ..

According to the digital information recording method and the digital information authentication method on the recording medium of claim 15, information recording and information authentication can be performed stably and reliably.

In the digital information recording method on the recording medium and the digital information authentication method on the recording medium according to the sixteenth aspect, information recording and information authentication can be performed by a specific pit whose reflectance changes at the tip or the end. .

According to the seventeenth aspect of the invention, the specific pit can be realized without giving a great change to the digital information recording method on the recording medium and the manufacturing process of the optical disc.

The method for preventing copy of a recording medium according to claims 18 and 19 can prevent the illegal copy of the recording medium by determining whether the recording medium is genuine or illegally copied. it can.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a digital information authenticating method on a recording medium according to the present invention and an optical disc copy preventing method using the same will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of use of an information recording apparatus, an optical disk and an information reproducing apparatus to which the present invention is applied. In the figure, 1 is an information recording apparatus to which the present invention is applied, 2 is an optical disc to which the present invention is applied, 3 is an information reproducing apparatus to which the present invention is applied, 4 controls the information reproducing apparatus 3, and the information reproducing apparatus 3 is used. It is an information processing device that processes reproduced information. The optical disk 2 by the information recording device 1
The digital information recorded on the disc is discriminated whether it is authentic or copied when it is reproduced by the information reproducing apparatus.
As a result, only a genuine optical disc is reproduced and processed by the information processing device 4. Further, if the pay software is recorded on the optical disc by the information recording apparatus, even if the optical disc information pay software is copied, the copied optical disc is not regarded as authentic by the information reproducing apparatus and the information is processed. Not sent to the device. Therefore, there is an effect of preventing an illegal trader from attempting to sell a copy of pay software without permission.

FIG. 2 is a block diagram showing an example of an information recording apparatus to which the present invention is applied. In the figure, reference numeral 5 denotes a data storage unit which stores digital data to be recorded on the optical disc 2 and a recording position on the optical disc as a pair. Here, the recording position is represented by a frame number and a bit number. A normal pit recording unit 6 digitally records the binary data notified from the data storage unit 5 at the position on the optical disk also notified from the data storage unit 5. As a recording method, when the binary data is 0, it is a pit (hole).
Is recorded, and when it is 1, no pit is recorded. The pits recorded here are determined so that when the pits are read out by the optical pickup of the optical disc reproducing device described later, the maximum reflected light amount (without pits) and the minimum reflected light amount (with pits) are obtained. . Reference numeral 7 denotes an authentication information recording position storage unit which stores information (authentication information) for authenticating that the optical disc is authentic and a recording position on the optical disc as a pair. The authentication information is recorded in the form of specific pits at the corresponding positions on the optical disc. The specific pit will be described later. Reference numeral 8 denotes a specific pit recording unit, which records a specific pit at the position on the optical disc notified by the authentication information recording position storage unit 7. A control unit 9 controls the operation of each of the above units.

FIG. 3 is a diagram for explaining an embodiment of an optical disc to which the present invention is applied. In FIG. 3, 2 is an optical disk and 10 is a specific pit. Binary information is recorded depending on whether or not there is a normal pit at the recording position where the specific pit of the optical disc to which the present invention is applied is not recorded.
On the other hand, a specific pit is recorded at a specific recording position. The difference between the normal pit and the specific pit is due to the difference in the amount of reflected light with respect to the light beam of the optical disk device. That is, where A is the reflected light amount of the light beam where there is no pit, B is the reflected light amount of the light beam where there is a normal pit, and C is the reflected light amount of the light beam where there is a specific pit, A> B, and C is an amount of light intermediate between A and B. In this embodiment, C = (AB) / 2 is set. The position (frame number and bit position) where the specific pit exists in the optical disc 2 is determined in advance, and this information is stored in the information recording device 1 and the information reproducing device 3 to which the present invention is applied.

FIG. 4 is a diagram showing in detail one embodiment of the specific pit. In the figure, the vertical axis represents the pit depth, and the horizontal axis represents the recording position on the optical disc. On the horizontal axis, (a) shows no pits, (b) shows normal pits, and (c) shows specific pits. As shown in (c), the specific pit has a depth different from that of a normal pit so that the reflectance of the light beam becomes an intermediate amount of light.

FIG. 5 is a block diagram showing an example of an information reproducing apparatus to which the present invention is applied. In the figure, 21 is an optical disk device, and 22 is an optical disk authentication unit. The information reproducing device is connected to the information processing device 4. Information processing device 4
Specifies to the optical disk device 21 the position on the optical disk where the information to be read is recorded. The specific position of the optical disk can be designated in units of 1 bit by the frame number and the bit position in the frame. The optical disc device 21 takes out recording information on the optical disc designated by the information processing device 4 and sends it to the information processing device 4. The components of the optical disk device 21 are as follows. An optical pickup 11 receives a servo signal from a control unit 16 described later, moves to a predetermined position on the optical disc, irradiates a light beam on the optical disc, and receives reflected light from a reflecting surface of the optical disc by a photodiode to receive light. Is converted into an electric signal and output. Reference numeral 12 is an analog waveform shaping unit that filters the output electric signal from the optical pickup 11. A binarization unit 13 compares the electric signal output from the analog waveform shaping unit 12 with a reference signal and outputs a binary signal of 1 or 0 to the outside. A frame synchronization unit 14 detects a frame synchronization signal from the binary sequence output from the binarization unit 13 and temporarily stores a data sequence after the frame synchronization signal in a frame buffer (not shown). An output unit 15 is a control unit 16 which will be described later in the frame buffer.
The binary information of the bit position specified by is output to the outside. A control unit 16 controls the operation of each unit of the optical disc device 21. Next, the optical disc authentication device 22 will be described. The optical disc authentication unit 22 is activated by a command from the information processing device 4 connected to the outside, takes out the authentication information recorded at a specific position of the optical disc 2 via the optical disc device 21, and processes the result to process the optical disc. Discriminates whether it is an authentic copy or a copy, and outputs the result to the information processing device 4. The components of the optical disc authentication device 22 are as follows. Reference numeral 17 denotes an authentication information position designation unit which stores the position of a specific pit which is the authentication information recorded on the optical disc, and when this is activated, this information is sent to the control unit 16 of the optical disc 21. 1
Reference numeral 8 denotes an authentication information frequency distribution storage unit which includes two counters (not shown), receives the authentication information at the position designated by the authentication information position designation unit 17 from the optical disc device 21, and sets it to 1
If so, the counter 1 is incremented by 1. If it is 0, the counter 0 is incremented by 1. A determination unit 19 checks the contents of the counter 1 and the counter 0 of the authentication information frequency distribution storage unit 17, and if they are substantially equal, determines that the optical disk is authentic and outputs a signal to that effect. On the other hand, if they are different, it is determined that the optical disc is not authentic, and a signal to that effect is output. Reference numeral 20 denotes a control unit that controls the above-mentioned units.

An example of the operation of the information recording apparatus of FIG. 2 and the information reproducing apparatus of FIG. 5 to which the present invention is applied will be described with reference to the flowchart of FIG.

[Operation of Information Recording Device] (1) The data storage unit 5 should be recorded as a normal pit 2
The value data and the recording position on the optical disk are stored. The authentication information recording position storage unit 7 stores the recording position on the optical disc where a specific pit should be recorded. (2) The control unit 9 activates the normal pit recording unit 6. (3) The normal pit recording unit 6 records the binary data stored in the data storage unit 5 at the corresponding recording position on the optical disc.

As long as there is data to be recorded in the data storage unit 5, (2) and (3) are repeated. (4) The control unit 9 activates the specific pit recording unit 8. (5) The specific pit recording unit 8 is the authentication information recording position storage unit 7
The specific pit will be recorded at the recording position notified by.

(4) and (5) are repeated for all the recording positions stored in the authentication information recording position storage section 7.

[Operation of Optical Disc Device 21] (11) When the control unit 16 receives the position information on the optical disc from the information processing device 4 or the optical disc authentication unit 22, the optical pickup 1 outputs a servo signal for reading that portion.
Output to 1. The optical pickup 11 moves to a predetermined position according to this signal. (12) The light beam emitted from the optical pickup 11 is reflected by the signal surface of the optical disc 10 and converted into electricity by the photodiode. This is modulated by the presence or absence of pits. (13) The output signal of the optical pickup 11 is filtered by the analog waveform shaping section 12 and input to the binarization section 13. FIG. 7 illustrates an electric signal output from the analog waveform shaping unit 12. Here, the vertical axis represents the electric signal level corresponding to the reflected light amount level, and the horizontal axis represents the position on the optical disc. In the figure, (a) is an output signal in the absence of a pit, and has a maximum level signal value.
(B) is an output signal at a normal pit and has a minimum level signal value. (C) is an output signal at a certain pit and has a signal value that is half the maximum level and the minimum level. (14) The binarization unit 13 binarizes the output of the analog waveform shaping unit 12 with the reference level. The broken line in FIG. 5 is the reference level. If the input level is higher than the reference level, 1 of the binary signal is output, and if equal or smaller, the binary signal 0 is output. Since the output of the analog waveform shaping section 12 is as shown in FIG. 7, it is normally set to 1 at a place without pits (a).
Is output, and 0 is output in the pit (b). On the other hand, in the area (c) where the specific pit is present, the output of the analog waveform shaping unit 12 is approximately the same level as the reference level, and a slight shift in the timing of binarization or a slight amount included in the reference voltage. The binarized output becomes 1 or 0 due to noise. In particular, if the reflected light reception amount C of the specific pit is set to the middle level between the maximum level and the minimum level of the normal pit, the binarized output becomes 1 at a probability of 50% and becomes 0 at a probability of 50%. (15) The frame synchronization unit 14 detects a frame synchronization signal from the binary sequence output by the binarization unit 13. Then, the subsequent data is temporarily stored in the frame buffer. (16) The output unit 15 outputs the information of the bit number designated by the control unit 16 among the frame information temporarily stored in the frame buffer as the output of the present optical disc device.

[Operation of Optical Disc Authentication Unit 22] (21) When the optical disc 2 is loaded, the control unit 20 is instructed by the information processing unit 4 to cause the control unit 20 to counter 1 and counter 0 (not shown respectively) of the authentication information frequency distribution storage unit 18. ) Is cleared to zero. (22) The control unit 20 takes out the recording position information of the authentication information from the authentication information position specifying unit 17. Then, this recording position information is sent to the control unit 16 of the optical disk device 21. (23) After that, the processes from (11) to (16) are performed. As a result, the output (authentication information 1 or 0) of the output unit 15 is output to the optical disc authentication unit 22. (24) The authentication information frequency distribution storage unit 18 increments the counter 1 (not shown) by 1 when the authentication information is 1. It is 0
If so, the counter 0 (not shown) is incremented by 1.

The above processes (22) to (24) are repeated N times (N is a positive integer indicating the number of read repetitions for one authentication information position). (25) The determination unit 19 checks the contents of the counter 1 and the counter 0 of the authentication information frequency distribution storage unit 18, and if they are substantially equal, determines that the optical disc is authentic and outputs a signal to that effect. On the other hand, if they are significantly different, for example, if the content of counter 1 is N and the content of counter 0 is 0, or if the content of counter 1 is 0 and the content of counter 0 is N, then the optical disc Is not authentic. Then, a signal to that effect is output to the outside. (26) According to the content of the signal notified from the optical disc authentication section 22, the information processing device 4 gives permission for the reading operation of the optical disc thereafter if the signal indicates that the disc is a genuine optical disc. If it is a signal indicating that there is no such signal, the subsequent read operation of the optical disc is prohibited.

In the case of a genuine optical disc, a specific pit is formed at the authentication information recording position. Therefore, the binary information output by the optical disk device in step (23) has a probability of approximately 50 as described in step (14) above.
% Is 1 and probability 50% is 0. Therefore, step (2
In 5), the contents of counter 1 and counter 0 are almost equal to each other, which are N / 2. If N is 100, each counter indicates a number of around 50. As will be described later, this value is significantly different from the value obtained by reading the copied optical disk, so that the determination unit 19 can correctly determine that the optical disc is a genuine optical disc.

Next, a genuine optical disc is illegally copied,
Consider a case where the copied optical disk is reproduced by the information reproducing apparatus according to the present invention. As a copying device, a so-called bit copying device is assumed, which reproduces all the information recorded on the optical disk as faithfully as possible.
A block diagram of this copying apparatus is shown in FIG. Reference numeral 2 is a first optical disk to which the digital information authentication method of the present invention is applied. Reference numeral 21 denotes an optical disk device, the structure of which is as shown in FIG. Reference numeral 5 is a normal pit recording portion, which records binary information designated at a designated recording position (frame number and bit number) of the second optical disc 23 by the presence or absence of pits. Reference numeral 24 is a control unit. The control unit 24 designates arbitrary position information for the optical disc device 21. Receiving this, the optical disk device 21 reads the corresponding portion of the first optical disk, and reads the binary information recorded therein and notifies the control unit 24 of the binary information. The control unit 24 outputs this binary information to the normal pit recording unit 5 together with the position information corresponding to this binary information.
The normal pit recording unit 5, which has received the two pieces of information, writes the corresponding binary information at the corresponding recording position on the second optical disc 23. The control unit 24 performs the above processing on all recording positions of the first optical disc 2.

Here, the optical disk device 21 outputs 1 at the pit-free recording position of the authentic first optical disk 2. Also, 0 at the recording position with normal pits
Is output. Then, the normal pit recording unit 5 records no pit or a normal pit at a corresponding position on the second optical disk 23 in correspondence with the binary information. Thus, the information recorded in the normal pits of the authentic first optical disc is the second information.
It is copied as it is to the optical disc. On the other hand, at the position where the specific pit is recorded, the analog waveform shaping unit 12 of the optical disk device 21 outputs a signal having a magnitude substantially equal to the reference value, and the binarization unit 13 receiving this outputs 1 or 0. Output either. Therefore, a random value of either 1 or 0 is output to the control unit 24. Therefore, the normal pit recording unit 5 is the second optical disc 2
At the relevant recording position 3 (the position where the specific pit was originally recorded), either one of no pit or normal pit is recorded. Different recording is performed for different specific pits.

Next, the operation of reproducing the thus copied optical disk by the information reproducing apparatus to which the present invention is applied will be described. In this case, the processes of the authenticating operation (22) to (24) of the genuine optical disc are repeated N times for one authentication information reading position. In the case of a copied optical disc, a normal pit is recorded in a position where a specific pit should be recorded in a genuine optical disc, or a pit is not recorded. If the normal pit is recorded, at this stage,
If the content of the counter 1 of the authentication information frequency distribution storage unit 18 is 0 and the content of the counter 0 is N, and conversely, if no pit is recorded, the content of the counter 1 is N and the content of the counter 0 is 0. Has become. Since the contents of the counter 1 and the counter 0 are significantly different in this way, the control unit 20 of the optical disc authentication unit determines that the optical disc is not genuine and outputs a signal to that effect to the information processing apparatus.
Receiving this, the information processing device 4 stops the processing for this optical disc.

As described above, in the present embodiment, the specific portion of the optical disc has a plurality of specific pits whose reflectance is about half of the maximum level and the minimum level, and the optical disc authentication section of the information reproducing apparatus has the above-mentioned structure. A specific pit is read a plurality of times, the authentication information frequency distribution storage unit obtains the distribution of the read binary signal, and the authentication unit has a distribution in which this distribution is determined by the pit (1 and 0 are approximately half each). The optical disc is certified as authentic only when Since the optical disc made by copying such an authentic optical disc does not have the above-mentioned specific pits, the frequency distribution of the authentication information when read a plurality of times as described above is different from that of the authentic optical disc. Does not consider this optical disc to be authentic. As described above, the information reproducing apparatus to which the digital information authentication method of the present embodiment is applied can be realized without adding new hardware to the conventional optical disk apparatus, and is compared with the optical disk copying apparatus of the type that performs bit-by-bit copying. Even so, it has realized an effective digital information authentication function.

If the pay software is recorded on the optical disk by the information recording apparatus, even if the optical disk is copied, the copied optical disk is not regarded as authentic by the information reproducing apparatus and the information is recorded as information. Not sent to the processor. Therefore, there is an effect of preventing an illegal trader from attempting to sell a copy of pay software without permission.

In this embodiment, the specific pit is M
When the individual pits are provided, the process of verifying the distribution of the reading results at the time when the reading is performed N times for each specific pit may be repeated for each specific pit.

[General Distribution] (Claim 11) In this embodiment, the reflectance of the specific pit is about half of the maximum level and the minimum level, but the reflectance is not limited to this. For example, the reflectance of a specific pit is an intermediate value between the maximum level and the minimum level, and is 1/3 from the maximum level.
The reflectance may be set to 2/3 from the minimum level, and the optical disc authentication unit may use whether or not it has a distribution characteristic matching the reflectance level as a criterion for determining whether or not the disc is a genuine optical disc. In addition, in the present embodiment, the reference value (voltage) of the binarization unit is about half of the maximum value and the minimum value, and the output of the specific pit is slightly deviated from the timing of binarization. It has been explained that the binarized output becomes 0 or 1 due to slight noise included in the reference voltage. If the shift in the binarization timing or the noise contained in the reference voltage is very small, the binarized output of the specific pit may not become 0 or 1 and may become either one. On the other hand, for example, by applying a small amount of noise to the reference voltage, the output for a specific pit can be surely distributed to 0 or 1. In this case, in order to prevent the performance deterioration due to noise with respect to the normal pits, for example, the noise voltage with respect to the reference voltage may be applied only to the specific pits. Applying noise to the reference voltage requires a change in the optical disk device, but can be achieved without a significant increase in hardware.

Further, in this embodiment, the frame synchronization unit 14,
Output unit 15, authentication information frequency distribution storage unit 18, determination unit 1
The control unit 20 and the control unit 20 have been described as being realized as software such as a microcomputer, but can also be realized as dedicated hardware, of course.

Further, in this embodiment, it is assumed that the authentication information (specific pit) is arranged in a portion of the storage area of the optical disc which is not subjected to the error correction process. For this reason, the error correction mechanism is not described as the configuration of the optical disk device 20. If the authentication information is arranged in the portion of the storage area of the optical disc that is subjected to the error correction processing, consideration for that is necessary. This is because this authentication method is based on forcibly introducing a bit error by recording a specific pit, but if the bit error is erased by the error correction mechanism, the original purpose is Is not achieved. In order to arrange the authentication information at the position where the error correction is performed, in the configuration of FIG. 5, an error correction mechanism is arranged between the frame synchronization unit 14 and the output unit 15, and the frame information detected by the frame synchronization unit is once framed. After the data is stored in the buffer and error correction processing is performed on the frame information, the output unit outputs the data at a predetermined bit position.

[More than error correction capability] (Claim 13) One arrangement for arranging the authentication information at the position where the error correction is performed is to arrange the specific pits on the optical disk after the error correction mechanism is provided as described above. In this case, assuming that half of the specific pits cause an error, the specific pits are arranged so that the error exceeds the error correction capability, and the distribution of the data passed through the error correction unit of the optical disk device is measured. By doing so, the binary uncertain output generated by the specific pit can be taken out as it is to the outside of the optical disc device, and therefore the optical disc authentication means can be provided outside the optical disc device. In this way, the authenticating function of the authentic optical disk can be realized in the software for driving the optical disk device without changing the hardware and software of the optical disk, for example, in the operating system or the application program.

[Error Correction Capability or Less] (Claim 14) Another configuration for arranging the authentication information at a position for receiving the error correction is that the optical disc authenticating unit is erroneous after the error correcting mechanism is provided as described above. The corresponding bit information of the binary data before correction is notified. At this time, in particular, when arranging the specific pits on the optical disk 2, by arranging so that half of the number of the specific pits in a certain error correction frame is below the error correction capability, a special effect is produced. You can That is, the output for a specific pit becomes an uncertain value of 0 or 1,
Even if a read error occurs equivalently due to this, the number of the error is about half of the specific pits, which is within the error correction capability, and the equivalent error is corrected by the error correction process. Therefore, there is an effect of concealing the existence of the present copy protection method without showing a sign of a data error in a copying apparatus which attempts to make an illegal copy. However, in order to do so, it is necessary to take out the above information from between the frame synchronization section and the error correction section of the optical disk device and notify the optical disk authentication section.

[Recording Modulation Code] (Claim 16) In this embodiment, when recording binary information, information 1 is recorded without pits and information 0 is recorded with pits. I explained it as something to do. That is, although the recording modulation code is not described, the present invention can be similarly implemented when the recording modulation code is used. For example, as a recording modulation method, a compact disc (CD)
In the method used for, the 8-bit information satisfies the condition that the number of 0s between 1 and 1 is 2 or more and 10 or less.
Converted to a 4-bit pattern. For example, 8-bit information (01100100) is (010001001000)
10). In order to combine such patterns, a 3-bit binary sequence is inserted so as to satisfy the above condition. By doing so, the number of 0s between 1s in all the binary information to be recorded is 2 or more and 10 or less. Then, the part of length L (10..0) that starts at 1 and ends at 0 before the next 1 is made to correspond to a pit of length L, and starts at 1 following this and ends at 0 before the next 1 Length M part (1
0. ． 0) is associated with a section of length M without pits, whereby binary information is associated with the presence or absence of pits. In such a case, the shape of the specific pit may be such that the reflectance of the leading end portion (or the trailing end portion) of a normal pit has an intermediate level between the maximum level and the minimum level. In the case of such a pit shape, even if uncertainties occur at the time of reading the leading end portion or the trailing end portion, the rule as the recording modulation method (that is, the number of 0s between 1 and 2 is 2 or more). (10 or less) can be satisfied, so that no inconvenience occurs in signal processing such as recording modulation decoding after reading.

[Reflectance] (Claim 17) Further, in the present embodiment, the change in the reflectance of the specific pit is explained as being caused by the change in the depth of the pit, but the present invention is not limited to this. Instead, the change in the reflectance may be realized by the change in the reflection characteristic of the reflection film. What is essential is that the reflectance when the light beam is emitted exhibits appropriate characteristics.

[M = 2, k = 1] (Claim 9) In addition, although an optical disc is used as the digital recording medium in the present embodiment, the present invention is not limited to this, and any optical disc may be used. It may be a digital recording medium. In short, the converter associates 1-bit digital information with one of two signal points S0 and S1 at a position other than a specific recording medium position, and each signal point has two levels V0 and V1. And outputs a specific signal point corresponding to the intermediate level V2 of these signal points at a specific recording medium position, and the inverse converter outputs an input signal point at a position other than the specific recording medium position. S0
S1 or S1 is processed to correspond to the closer one, and the input signal point is S0 or S1 at the position on the specific recording medium.
It is determined that there is a specific signal point because the decoded S0 and S1 are about half each, and the authenticating means determines that there is a specific signal point. Alternatively, the digital information on the recording medium may be determined to be authentic.

[Invention of Claim 7] Furthermore, the correspondence between the digital information on the recording medium and the signal points is not limited as described above, but the digital information is not present at a specific recording position on the recording medium. Is output corresponding to one of the m signal points, and k other than the above-mentioned m signal points is output at a specific position on the recording medium.
A converter that outputs one of the signal points, a reader that reads the signal point on the recording medium as a signal point containing noise, and the output of the reader at each position other than the specific position. A process of making the closest one of the m signal points, and making the signal point output from the recording medium correspond to the closest one of the m signal points at the position on the specific recording medium is performed. An inverse converter and an authentication means for judging that the recording medium or the digital information on the recording medium is authentic because the frequency distribution of the m signal points as the processing result for each specific time shows a predetermined distribution. It may have.

Next, one embodiment of a digital information secret recording method on a recording medium and an optical disc copy preventing method using the same according to the present invention will be described in detail with reference to the drawings.

FIG. 9 is a block diagram showing an example of an information recording apparatus, an optical disk and an information reproducing apparatus to which the digital information secret recording system of the present invention is applied. In the figure, 4
Reference numeral 1 denotes an information recording device to which the present invention is applied, which is an optical disc 4
2. Normal digital information is recorded in 2 and secret information is recorded in the optical disc. Reference numeral 43 denotes an information reproducing apparatus to which the present invention is applied, which takes out secret information together with digital information recorded on the optical disc. An information processing device 64 processes the information reproduced by the information reproducing device 43.

Normal digital information and secret digital information recorded on the optical disc 42 by the information recording device 41 are reproduced by the information reproducing device 43, and the information is processed by the information processing device 64. Optical disk 42 here
The secret digital information recorded above cannot be read or copied using a copy tool. By preventing the information processing device 64 from performing appropriate processing without the secret digital information, only a genuine optical disc is reproduced and processed by the information processing device 64. Further, if the pay software is recorded on the optical disk in this way, no economic benefit can be obtained even if copying is performed, so that there is a copy protection effect.

FIG. 10 is a block diagram showing an example of an optical disk recording apparatus to which the present invention is applied. In the figure, 4
A first data storage unit 4 stores digital data to be recorded on the optical disc 42 in a pair with a recording position on the optical disc. Here, the first binary data and the recording position are 1
There is a one-to-one correspondence. The recording position is represented by a frame number and a bit number. A normal pit recording unit 45 digitally records the binary data notified from the first data storage unit 44 at the similarly notified recording position on the optical disc. As a digital recording method, pits are recorded when the binary data is 1, and no pits are recorded when the binary data is 0. The pits recorded here are determined so as to have the maximum reflected light amount (without pits) and the minimum reflected light amount (with pits) when the pits are read by the optical pickup of the optical disk reproducing device described later. .
A second data storage unit 46 stores second binary data to be recorded on the optical disc 42 in association with the recording position on the optical disc. The second binary data is secret data and is recorded in the form of specific pits. Second here
There is a one-to-one correspondence between the binary data and the recording position. That is, one recording position corresponds to 1-bit second binary data. FIG. 11 shows the second data to be recorded in the optical disc 2.
2 shows the binary data and the type and position of a specific pit recorded corresponding to the binary data. Here, N is a serial number corresponding to each bit of the second binary data, the minimum value is 1 and the maximum value is Nmax (Nmax = 6 in FIG. 11).
4). The specific pit will be described later. A specific pit recording unit 47 records the first or second specific pit corresponding to the binary data stored in the specific data storage unit 46. A control unit 48 controls the operation of each of the above units.

FIG. 12 shows an optical disk 42 to which the present invention is applied.
It is a figure explaining one Example. Binary information is recorded on the optical disc to which the present invention is applied depending on whether or not there are ordinary pits, and at the same time, one of two types of specific pits is recorded corresponding to the secret binary information of 1 bit. The two types of specific pits are referred to as a first type of specific pit 49 and a second type of specific pit 50. The reflected light quantity of the light beam where there is no pit is A, the reflected light quantity of the light beam where there is a normal pit is B, the reflected light quantity of the light beam where there is a specific type 1 pit is C, and the second kind When the amount of reflected light of the light beam at the specific pit is marked as D, A>C>D> B.

These levels are defined as follows.
First, the level of A and B is the level A + in the middle of A and B
The difference between A and B is selected to be sufficiently large so that the error rate is sufficiently small in the binary determination with B / 2 as the reference level. In other words, the level of A is determined so that the probability that the actual reflected light amount without the pit is below the threshold value is about 10 ^ 6,
Further, the level of B is determined such that the probability that the actual reflected light amount with the pit exceeds the reference level is about 10 ^ 6. On the other hand, C and D are selected as follows. The B level is selected so that the probability that the actual reflected light amount of the light beam at the specific pit of the first type falls below the reference level is about 0.1. That is, the B level is selected to be slightly higher than the reference level. Similarly, the level of C is selected so that the probability that the actual reflected light amount of the light beam at the specific pit of the second type exceeds the reference level is about 0.1. That is, the level of C is selected to be a little lower than the reference level.

The positions (frame number and bit position) where these two types of specific pits are present in the disc 2 are predetermined, and this information is stored in the information recording device 41 and the information reproducing device 43 to which the present invention is applied. Is also remembered. However, this information is written in the ROM or the like as the firmware of the optical disk recording device or the reproducing device, and is secret to the user of the general optical disk device.

FIG. 13 is a diagram showing an example of the specific pit in detail. In the figure, the vertical axis represents the pit depth, and the horizontal axis represents the position on the optical disc. In the figure, (a) shows no pit, (b) shows a normal pit, (c) shows a first specific pit, and (d) shows a second specific pit. As shown in (c), the amount of reflected light of the light beam is closer to the intermediate amount of light than that without the pit, and the amount of reflected light of the light beam of the second specific pit is more than that with the pit. Also, the depth of the pit has a depth different from that of a normal pit so that the light amount is close to the intermediate light amount.

FIG. 14 is a block diagram showing an example of an information reproducing apparatus to which the present invention is applied. In the figure, 21 is an optical disk device, and 51 is a secret information reproducing section. The information reproducing device is connected to the information processing device 64. The information processing device 64 specifies to the optical disc device 21 the position on the optical disc 42 where the information to be read is recorded. The recording position of the optical disk 42 can be designated in 1-bit units by the frame number and the bit position within the frame. The optical disc device 21 takes out recording information on the designated optical disc from the information processing device 64 and sends it to the information processing device 64. Next, the secret information reproducing unit 51 will be described. The secret information reproducing unit 51 is activated by a command from the information processing device 64 connected thereto, and takes out the partial secret information recorded at a plurality of specific positions of the optical disc 42 via the optical disc device 21. The result is processed, the secret information is reproduced, and the result is processed by the information processing device 6.
Output to 4. The constituent elements of the secret information reproducing unit 51 are as follows. A secret information position designation unit 52 stores the position of a specific pit which is secret information recorded on the optical disc 42, and when this is activated, this information is sent to the control unit 16 of the optical disc 21. Reference numeral 53 denotes a secret information frequency distribution storage unit which receives the secret information at the position designated by the secret information position designation unit 52 from the optical disk device 21, and if it is 1, increments a counter 1 (not shown) by 1. If it is 0, the counter 0 (not shown) is incremented by 1. A determination unit 54 is a secret information frequency distribution storage unit 53.
The secret information is judged from the frequency distribution of the secret information stored in and output to the outside. A control unit 55 controls the above-mentioned units.

Information recording apparatus to which the present invention is applied (FIG. 10)
An example of the operation of the information reproducing apparatus will be described with reference to the flowchart of FIG.

[Operation of Information Recording Device (FIG. 10)] (31) The control unit 48 activates the normal pit recording unit 45. (32) The normal pit recording unit 45 is the first data storage unit 4
The first binary data stored in No. 4 is digitally recorded at the corresponding recording position on the optical disc. When the binary data is 0, a normal pit is recorded, and when it is 1, no pit is recorded. This process is repeated as long as there is data to be recorded in the first data storage unit 44. (33) The control unit 48 activates the specific pit recording unit 47. At this time, the N register (not shown) is set to 1. The value of the N register indicates the number of the second binary data. (34) If N> Nmax, proceed to (36). Otherwise, proceed to (37). Here, Nmax is the number of bits of secret information to be recorded. (35) The specific pit recording unit 46 is the second data storage unit 4
The recording position on the optical disc corresponding to the Nth second binary data stored in 6 is read, and a specific pit corresponding to the Nth binary information is digitally recorded at this recording position. When the binary data is 0, the first type of specific pit is recorded, and when the binary data is 1, the second type of specific pit is recorded. (36) Set N = N + 1 and proceed to (34). (37) This operation ends.

[Operation of Optical Disk Device (FIG. 1421)] (41) When the control unit 16 receives the position information on the optical disk from the outside (the information processing device 64 or the secret information reproducing unit 51), it outputs a servo signal for reading that part. Output to the optical pickup 11. The optical pickup 11 moves to a predetermined position according to this signal. (42) The light beam emitted from the optical pickup 11 is reflected by the signal surface of the optical disc 42 and converted into electricity by the photodiode. This is modulated by the presence or absence of pits. (43) The output signal of the optical pickup 11 is filtered by the analog waveform shaping section 12 and input to the binarization section 13. FIG. 16 illustrates an electric signal output from the analog waveform shaping unit 12. Here, the vertical axis represents the electric signal level corresponding to the reflected light amount level, and the horizontal axis represents the position on the optical disc. The broken line indicates the reference level for binary determination. In the figure, (a) is an output signal in the absence of a pit, and has a maximum level signal value. (B) is an output signal at a normal pit and has a minimum level signal value. (C) is an output signal at the position where the first specific pit is present, and has a signal value slightly higher than the reference level. (D)
Is an output signal at the position of the second specific pit, and has a signal value of a level slightly smaller than the reference level. (44) The binarization unit 13 binarizes the output of the analog waveform shaping unit 12 with the reference level. The part indicated by the broken line in FIG. 16 is the reference level. If the input level is higher than the reference level, 0 of the binary signal is output, and if equal or smaller than the reference level, 1 of the binary signal is output. The output of the analog waveform shaping unit 12 is shown in FIG.
As a result, 0 is output where there are no pits (a), and 1 is output where there are normal pits (b). On the other hand, in the area (c) where the first specific pit is present, the output of the analog waveform shaping unit 12 is slightly larger than the reference level. Therefore, if the reflected light reception amount C of the first specific pit is determined as described above, The digitized output becomes 0 with a probability of 80% and becomes 1 with a probability of 20%. Further, since the output of the analog waveform shaping unit 12 is slightly smaller than the reference level in the area (d) where the second specific pit is present, if the reflected light receiving amount D of the second specific pit is determined as described above, it is binarized output. Has a 20% probability of 0 and a 80% probability of 1. (45) The frame synchronization unit 14 detects a frame synchronization signal from the binary sequence output by the binarization unit 13. Then, the subsequent data is temporarily stored in the frame buffer. (46) The output section outputs the information of the bit number designated by the control section 16 from the frame information temporarily stored in the frame buffer as the output of the optical disk device 21.

[Operation of Secret Information Reproducing Section (51 in FIG. 15)] (51) When the optical disk 42 is loaded, the information processing device 6
The control unit 55 sets the N register to 1 in response to the command of 4. N
The content of the register indicates the number of secret information to be reproduced. (52) The control unit 55 checks whether N> Nmax.
If yes, go to (61), if no, go to (53).
Proceed to. (53) The control unit 55 sets the I register to 1. The I register indicates the number of times of reading. Further, the counter 1 and the counter 0 of the secret information frequency distribution storage unit 53 are cleared to zero. (54) The control unit 55 checks whether I> Imax.
If yes, go to (59); if no, go to (55).
Proceed to. Imax is the maximum value of the number of read times. (55) The control unit 55 takes out the recording position information of the secret information from the secret information position specifying unit 52. Then, this recording position information is sent to the control unit 16 of the optical disk device 21. (56) After that, the processes from (41) to (45) are performed. As a result, binary read information (1 or 0) is output to the secret information reproducing unit 51. (57) The secret information frequency distribution storage unit 53 increments the counter 1 by 1 if the read information is 1. If it is 0, the counter 0 is incremented by 1. (58) Set I = I + 1 and proceed to (54). (59) The determination unit 54 checks the contents of the counter 1 and the counter 0 of the secret information frequency distribution storage unit 53, and if the counter 1 is large, 1 is processed, and if the counter 0 is large, 0 is processed as the Nth secret information. Output to the device 4. (60) Set N = N + 1 and proceed to (52). (61) The information processing device 4 performs a predetermined process using the Nmax bits of secret information notified from the secret information reproducing unit 41.

Next, by the information recording device, the optical disc, and the information reproducing device configured and operating as described above, [1] the secret information recorded on the optical disc is not exposed by the ordinary optical disc device, and [2] secretly. The information that should be reproduced can be successfully reproduced by the information reproducing apparatus, and [3] the secret information cannot be reproduced from the copied optical disc when the optical disc on which the secret information is recorded is copied.

[1] Secret information recorded on an optical disc is not exposed by an ordinary optical disc device. In the following discussion, it is assumed that there is an attacker who wants to disclose secret information. Consider that the attacker has a normal optical disk device and attempts to read the optical disk recorded by the information recording apparatus with the normal optical disk device. Here, the secret information is recorded by the first and second specific pits. In this way, what is recorded by the specific pit is kept secret (to the attacker) except in a specific range. Also, the position where the specific pit is recorded is kept secret (to the attacker) except in a specific range. Furthermore, the process of reproducing the secret information in the information reproducing apparatus is also secret (to the attacker) except for a specific range. By doing so, the secret information recorded on the optical disk by the information recording apparatus is not exposed by the normal optical disk apparatus of the attacker.

Next, even if the position where the secret information is recorded is known to the attacker, if the secret information reproduction process is secret and the number of bits of the secret information is large, the secret information recorded on the optical disk will be attacked. I will show that it is not exposed by your normal optical disk device. Suppose now that the secret information is S, and this is Nmax bits of information. It is assumed that the attacker already knows the position where this secret information is recorded as a specific pit. In this case, the attacker can obtain the result (denoted as R) of the binary determination for the positions of the Npit specific pits. However, as described above, when the binary information recorded in the specific pit is read once by the ordinary optical disk device, there is an error rate of about 0.1. Therefore, of the Nmax bits, about 0.1 x Nmax bits are erroneous on average. Now, assuming that Nmax = 200, about 20 bits on average in R are different from the true secret information. Therefore, on the average, the true secret information S is a binary sequence different from R by 20 bits. However, I do not know which 20 bits are different. Therefore, in order to estimate S from R by the attacker, on average, the difference between R and S, which is the number (200C20) when extracting 20 balls from a box containing 200 different balls, is tried. It is necessary to make mistakes. Since this value is a large value of about 10 23, it becomes very difficult for an attacker to obtain S from R by trial and error. In conclusion, even if the position where the secret information is recorded as the specific pit is known to the attacker, the secret information recorded on the optical disc is not exposed by the ordinary optical disc device.

[2] Information to be kept secret can be successfully reproduced by this information reproducing apparatus.
2 times are read, and 2 is judged by the majority decision of the result.
Value information is determined. That is, of the Imax read results, the larger one of the number of times of 1 and the number of times of 0 is determined. Even if the bit error rate is about 0.1, if the number of times of reading is large, the error rate of the majority decision is sufficiently small. For example, when the bit error rate is 0.1 and the number of readings is 23, the majority decision error rate is 4.6x10 ^ (-7). This is a small error rate, which is equivalent to the error rate of 10 ^ (-6) for normal pits. After that, if an error correction mechanism similar to the error correction for normal pits is introduced, error-free reproduction is possible.

[3] When the optical disc on which the secret information is recorded is copied, the secret information cannot be reproduced from the copied optical disc. The first optical disc on which the secret information is recorded is the second optical disc by the bit copy machine. Shall be copied to. Here, a bit copy machine equivalent to that shown in FIG. 8 is considered. That is, the bit copy machine does not know that the secret information is recorded by the specific pits on the first optical disc, and assumes that the secret information is recorded by the normal pits. Information is written on the second optical disk in correspondence with normal pits. At this time, when the secret information portion (the portion recorded in the specific pit) of the first optical disc is read and converted into binary information, 10 to 20% of errors are included. Then, this binary information is recorded in the second optical disc in the normal pit. Therefore, when this second optical disk is read by this information reproducing apparatus, this error is not eliminated even by the majority decision, so that the information reproduced from the information reproducing apparatus contains an error. Therefore, the true secret information is not reproduced from the copied second optical disc.

As described above, in this embodiment, the reflectance of the specific portion of the optical disc between the maximum level and the minimum level is slightly smaller than the maximum level and slightly larger than the minimum level in correspondence with the information to be kept secret. By recording two types of specific pits, the secret information reproducing unit performs the reading process for the specific pits a plurality of times, and determines the binary information by the majority decision of the binary information read a plurality of times. Replay confidential information. Since an optical disc produced by copying such a genuine optical disc does not have the above-mentioned specific pits, true secret information cannot be reproduced by the majority decision when reading a plurality of times as described above. As described above, in this embodiment, the secret information recorded on the optical disc is not exposed by the ordinary optical disc device, and the information to be kept secret can be successfully reproduced by the information reproducing device.
When the optical disc on which the secret information is recorded is copied, the secret information can be recorded on the optical disc such that the secret information cannot be reproduced from the copied optical disc.

[Copy protection] (Claim 19) Then, by preventing the information processing apparatus from performing the necessary processing without the secret digital information, only a genuine optical disk is reproduced and processed by the information processing apparatus. It Further, if the pay software is recorded on the optical disk in this way, no economic benefit can be obtained even if copying is performed, so that there is a copy protection effect.

[Dummy Bit] (Claim 6) In this embodiment, it is assumed that an attacker who wants to reveal secret information makes only one copy from one genuine optical disk. Discussed methods of recording that would not be exposed. Here, it is assumed that the attacker makes a plurality of copies and takes the difference between the digital information recorded on the optical disc of the copies. At this time, a difference occurs in the portion recorded by the specific pit. And when the attacker noticed the difference, he made many copies,
A majority decision is made on the part with the difference. This reveals sensitive information. When such a threat is assumed, not only the specific pit is recorded at the position corresponding to the secret information on the recording medium, but also the first or second specific pit is recorded at the other appropriate recording position. It shall be recorded. If such recording is performed, confidential information will not be exposed even if the majority decision is made at the recording positions of all the specific pits.

[Addition of Noise] (Claim 15) In the present embodiment, when the first and second types of specific pits are set, the error rate due to a slight amount of noise that naturally exists becomes an appropriate value. However, the error rate may be controlled by applying a small amount of noise to the reference voltage.

[Relationship with error correction] (Claims 13 and 1)
4) Further, in this embodiment, it is assumed that the secret information is arranged in a portion of the storage area of the optical disc which is not subjected to the error correction process. For this reason, no description has been made of the error correction mechanism as the configuration of the optical disk device 20. If the secret information is arranged in a portion of the storage area of the optical disc that is subjected to the error correction processing, the two configurations described in the description of the digital information authentication method described above are possible.

[Recording Modulation Code] (Claim 16) Further, although the recording modulation method was not described in recording the digital information on the optical disk in the present embodiment, the present invention when the recording modulation method is used. Can be implemented similarly. This method is not the same as the method described in the above description of the digital information authentication method, and the description thereof will be omitted.

[Reflectance] (Claim 17) Further, in the present embodiment, the change in the reflectance of the specific pit is explained as being caused by the change in the depth of the pit, but the present invention is not limited to this. Instead, the change in the reflectance may be realized by the change in the reflection characteristic of the reflection film. What is essential is that the reflectance when the light beam is emitted exhibits appropriate characteristics.

[Recording Medium] (Claim 8) Although an optical disc is assumed as the recording medium in this embodiment, the present invention is not limited to this.
In short, the converter associates 1-bit input digital information with one of two signal points S0 and S1 at a position other than a specific recording medium position, and each signal point has two levels V0, Record on a recording medium corresponding to V1,
At the position on the specific recording medium, when the other 1-bit input digital information is 0, it corresponds to the specific signal point S00 having the level V00, and when the input digital information is 1, the specific signal point S11 having the level V11. , Where V0 <V00 <V11 <V1 and V0
The levels of 0 and V11 are set so as to cause an error with a certain probability in the binary judgment due to noise applied on the recording medium, and the inverse converter is other than the specific position on the recording medium. At the position of, the processing for associating the input signal point with S0 or S1 is performed, and at the position on the specific recording medium, the processing for associating the input signal point with S0 or S1 is repeated a plurality of times. It is sufficient that the secret information is recorded by reproducing the digital information corresponding to the larger one of S0 and S1 which are the processing results for one specific position.

[General m, k] (Claim 5) Furthermore, the correspondence between the digital information to be recorded on the recording medium and the signal points is not limited to the above.
In short, the converter records the first digital information at each position other than the specific position on the recording medium in correspondence with one of the m signal points, and the second digital information at the specific position on the recording medium. Digital information is k other than the above m signal points.
Output corresponding to one of the signal points, and the inverse converter corresponds the output of the reader to the nearest one of the m signal points at each recording medium position other than the specific position. Then, at the specific recording medium position, the signal point output from the reader is made to correspond to the closest one of the m signal points a plurality of times,
One of the k signal points is determined by the frequency distribution of the m signal points, which is the processing result for each specific recording medium position and one specific position, and the second digital information corresponding thereto is determined. Of the specific k signal points, the position on the specific recording medium, and the processing related to the specific signal points are kept secret except for a specific range. Any one of the signal points may be secretly recorded except for a specific range.

[Recording] (Claim 4) Further, if it is not necessary to secretly record and only digital information is recorded, the existence of the specific k signal points and the position on the specific recording medium. It is not necessary to keep the processing regarding the above-mentioned specific signal point secret.

[Claims 1, 2 and 3 (communication path)] In this embodiment, the digital information authentication method and secret recording method when digital information is recorded on a recording medium have been described. The present invention is not limited to this, and can be similarly applied when digital information is transmitted via a communication path. The structure and operation thereof are the same as those of the digital recording medium, and the description thereof will be omitted.

[0107]

As described above, according to the present invention, a method for authenticating digital information for determining whether digital information recorded on a recording medium such as an optical disk or digital information transmitted via a communication path is authentic. Can be provided. Further, according to the present invention, it becomes possible to transmit secret information via a communication path and record secret information on a recording medium. Furthermore, by using these, it becomes possible to prevent copying of digital information recorded on a recording medium.

[Brief description of drawings]

FIG. 1 is an information recording device, an optical disc, to which the present invention is applied.
And block diagram of a first embodiment of an information reproducing apparatus

FIG. 2 is a block diagram of an embodiment of an information recording device to which the present invention is applied.

FIG. 3 is a schematic view of an embodiment of an optical disc to which the present invention is applied.

FIG. 4 is a diagram showing an example of specific pits of an optical disc to which the present invention is applied.

FIG. 5 is a block diagram of an embodiment of an information reproducing apparatus to which the present invention is applied.

FIG. 6 is a flowchart showing an example of operations of an information recording device and an information reproducing device to which the present invention is applied.

FIG. 7 is a diagram showing an example of an output signal of an analog waveform shaping unit of an optical disc device to which the present invention has been applied.

FIG. 8 is a block diagram of a copy device according to the present invention.

FIG. 9 is an information recording device to which the present invention is applied, an optical disc,
And block diagram of a second embodiment of the information reproducing apparatus

FIG. 10 is a block diagram of an embodiment of an information recording device to which the present invention is applied.

FIG. 11 is a diagram showing an example of second binary data, types of specific pits recorded corresponding thereto, and recording positions.

FIG. 12 is a schematic view of an embodiment of an optical disc to which the present invention is applied.

FIG. 13 is a diagram showing an example of specific pits of an optical disc to which the present invention is applied.

FIG. 14 is a block diagram of an embodiment of an information reproducing apparatus to which the present invention is applied.

FIG. 15 is a flowchart showing an example of operations of an information recording device and an information reproducing device to which the present invention is applied.

FIG. 16 is a diagram showing an example of an output signal of an analog waveform shaping section of an optical disk device to which the present invention has been applied.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H04K 1/00 Z H04L 9/00 9/10 9/12

Claims (19)

[Claims] 1. At each time other than a specific time, the first digital information is output on the communication path in association with one of the m signal points, and at a specific plurality of times, the second digital information is output. A converter for outputting on the communication path in correspondence with one of k signal points other than the m signal points, a communication path for transmitting the signal point while being disturbed by noise, At each time other than the specific time, by inputting the signal point of the output of the communication channel and making it correspond to the closest one of the m signal points, the signal is output from the communication channel at the specific time. The signal point corresponding to the closest one of the m signal points is processed, and one of the k signal points is determined by the frequency distribution of the m signal points, which is the processing result at each specific time. By determining one Digital information transmission method characterized by comprising the inverter to restore the second digital information. 2. One of the k specific signal points by secreting a process for a specific plurality of times, a specific k signal points, and the specific signal point except a specific range. 2. The digital information transmission system according to claim 1, wherein one of them is secretly transmitted except for a specific range. 3. At each time other than a specific time, digital information is output on the communication path in association with one of m signal points, and at a plurality of specific times, information other than the m signal points is output. a converter that outputs one of the k signal points,
A communication path that transmits the above signal points while being disturbed by noise, and a signal point at the output of the communication path at each time other than the above specific time are input, and these are input to the nearest one of the m signal points. And an inverse converter that performs processing for associating the signal point output from the communication path with the closest one of the m signal points at the specific time,
When the frequency distribution of the above-mentioned m signal points, which is the processing result for each specific time, shows a predetermined distribution, the converter connected to the communication path is regarded as authentic, or is transmitted via this communication path. A method for authenticating digital information on a communication path, which comprises an authenticating means for judging the received digital information to be authentic. 4. The first digital information is recorded at each position other than the specific position on the recording medium in correspondence with one of the m signal points, and the second digital information is recorded at the specific position on the recording medium. A converter that outputs information corresponding to one of k signal points other than the above m signal points;
A reader that reads a signal point on a recording medium as a signal point containing noise, and an output of the reader at each recording medium position other than the specific position is made to correspond to the closest one of the m signal points. , At the specific recording medium position, a process of making the signal point output from the reader correspond to the closest one of the m signal points is performed a plurality of times, and the process is performed for each specific recording medium position and one specific position. One of the k signal points is determined by the frequency distribution of the m signal points which is the processing result, and an inverse converter for reproducing the second digital information corresponding to the one is determined. Digital information recording method. 5. The existence of the specific k signal points, the specific positions on the recording medium, and the processing relating to the specific signal points are kept secret except for a specific range, whereby the k specific signal points are identified. 5. The digital information recording method according to claim 4, wherein one of them is secretly recorded except in a specific range. 6. The converter outputs to a plurality of positions other than the position of a specific recording medium in association with one of k signal points other than m signal points. The digital information recording method described in 5. 7. Digital information corresponding to one of m signal points is output at each position other than the specific recording position on the recording medium, and other than the m signal points at the specific recording medium position. , A converter that outputs one of the k signal points, a reader that reads the signal point on the recording medium as a signal point containing noise, and an output of the reader at each position other than the specific position. Corresponding to the closest one of the m signal points, and the signal point output from the recording medium at the specific position on the recording medium to the closest one of the m signal points. And the frequency distribution of the above-mentioned m signal points, which is the processing result for each specific time, show a predetermined distribution, so that the recording medium or digital information on the recording medium is Digital information authentication method on a recording medium, characterized in that it comprises an authentication means for determining that Tadashina ones. 8. A converter associates 1-bit input digital information with one of two signal points S0 and S1 at a position other than a specific recording medium position, and each signal point has two levels. Recording is performed on a recording medium in correspondence with V0 and V1, and when other 1-bit input digital information is 0 at a position on the specific recording medium, it is made to correspond to a specific signal point S00 having a level V00, and input digital information Is corresponding to the specific signal point S11 having the level V11, where V0 <V00 <V11 <V1
The levels of V00 and V11 are set so as to cause an error with a certain probability in the binary judgment due to the noise applied on the recording medium, and the inverse converter is other than the specific position on the recording medium. At the position of, the input signal point is processed to correspond to S0 or S1, and at the position on the specific recording medium, the input signal point is set to S0 or S1.
The secret information is recorded by repeating the processing corresponding to 1 a plurality of times, and reproducing the digital information corresponding to the larger one of S0 and S1 which are the processing results for each specific recording medium position and one specific position. A digital information recording system on a recording medium according to claim 5 or 6. 9. A converter associates 1-bit digital information with one of two signal points S0 and S1 at a position other than a position on a specific recording medium, and each signal point has two levels V0. , V1 and outputs a specific signal point corresponding to an intermediate level V2 of these signal points at a specific recording medium position, and the inverse converter outputs an input signal at a position other than the specific recording medium position. Point is S0 or S
1 is performed, and the process of making the input signal point at the position on the specific recording medium closer to either S0 or S1 is repeated a plurality of times. As a result, the decoded S0 and S1 are The recording medium on the recording medium according to claim 7, wherein it is determined that the specific signal point exists by being about half each, and at this time, the authentication means determines that the recording medium or the digital information on the recording medium is authentic. Digital information authentication method. 10. The digital recording medium is an optical disk, and the converter is a pit having a maximum reflectance as a signal point S0 when the input 1-bit digital information is 0 at a position other than a specific position on the optical disk. 1
When the signal point S1 at this time is pits, the pits having the minimum reflectance are recorded on the optical disc, and at the position on the specific optical disc, when the other input 1-bit digital information is 0, the reflectance is at the maximum and minimum levels. Of a specific pit whose level is slightly higher than the intermediate level, and when the digital information is 1, the specific pit whose reflectance is slightly lower than the intermediate level is recorded. At a position other than the specific position on the optical disc, the process of correlating the input signal point with S0 or S1 is performed, and with the position on the specific optical disc, the process of correlating the input signal point with S0 or S1 is performed a plurality of times. Repeatedly, the digital information corresponding to the larger one of S0 or S1 which is a plurality of processing results for each specific optical disk position and one specific position is obtained. Digital information recording system on a recording medium according to claim 8, wherein the recording of secret information by raw. 11. A digital recording medium is an optical disc for recording 1-bit digital information in association with a pit having a maximum reflectance and a pit having a minimum reflectance, and a converter is provided on a predetermined position on the optical disc. In the above, a specific pit whose reflectance is at an intermediate level between the maximum level and the minimum level is recorded, and the inverse converter performs a reading process on the specific pit a plurality of times to read binary data. 10. The digital information authenticating method on a recording medium according to claim 9, wherein the optical disc is judged to be authentic only when the distribution of the optical disc coincides with the distribution determined by the specific pit. 12. The reflectance of a specific pit has a value of about half of the maximum level and the minimum level, and the signal distribution corresponding to this specific pit is such that 0 and 1 are approximately half each. Method of digital information authentication on computer recording media. 13. When arranging specific pits on an optical disk, the pits are arranged so that half of the number of specific pits in an error correction frame has an error correction capability or more, and binary data after error correction processing is processed. The digital information recording method on the recording medium according to claim 10, or the digital information authentication method on the recording medium according to claim 11. 14. When arranging specific pits on an optical disc, half of the number of specific pits in an error correction frame are arranged so as to have an error correction capability or less, and binary data before error correction processing is processed. The digital information recording method on the recording medium according to claim 10, or the digital information authentication method on the recording medium according to claim 11. 15. A small amount of noise is applied to the reference voltage in the binarization process of a specific pit.
The digital information recording method on the recording medium according to 0 or the digital information authentication method on the recording medium according to claim 11. 16. A digital information recording method on a recording medium according to claim 10, wherein the reflectance of the specific pit changes at the tip or the end.
Digital information authentication method on the recording media described. 17. A digital information recording system or recording method according to claim 10, wherein the change of the reflectance of a specific pit is caused by the change of the height of the pit or the reflection characteristic of the reflection film. Item 11. A digital information authentication method on a recording medium according to item 11. 18. The digital information recording method on the recording medium according to claim 5, 8 or 10, is used to determine whether the recording medium is genuine or illegally copied. Copy protection method for recording media. 19. The digital information authentication method on a recording medium according to claim 7, 9 or 11 is used to determine whether the recording medium is genuine or illegally copied. Copy protection method for recording media.