JP7286862B1 - Appraisal/verification device using optical disk error pattern chart and digital watermarking using error pattern - Google Patents

Abstract

[Problems to be solved] When an optical disk has a read failure, a method and device for appraising and verifying whether or not evidence is destroyed or forged, an instrument device, an individual identification method for the disk, and a sure way to detect unauthorized duplication. To provide an electronic watermark which enhances the quality and an optical disk embedded with the watermark. [Solution] The method is characterized in that when an optical disc is traced, the time series of recording and the time series of errors match, and even if data cannot be read, the traces and time series of recording sessions are included in the error distribution. By using the property that the data is recorded and stored, and the distribution situation reflects the record history, the error pattern chart is used to estimate the recording amount or recording time of the recording session, and to appraise and verify evidence destruction and forgery. In addition, in order to realize an optical disc with an observable electronic watermark on the error pattern chart and an increased certainty that it can be detected when unauthorized duplication is performed, the individuality of the optical disc is made using the property that errors cannot be copied. identify. [Selection drawing] Fig. 4

Description

The present invention provides a method and apparatus for inspecting optical discs for data storage and appraising and verifying whether evidence has been destroyed or forged, a disc individual identification method, and a method for detecting unauthorized duplication. The present invention relates to an optical disc with enhanced certainty.

An optical disk is a plate made of light-transmissive plastic or the like, which is provided with a recording film and a reflective film, and which has grooves formed on the inside. be. Since it is an industrial product, quality control is performed. For example, for an individual with eccentricity in the donut-shaped hole in the center of the disk, when the disk is rotated, the track blurs and the optical head exceeds the tracking limit and becomes unreadable. treated as defective. Alternatively, an individual with poor groove formation accuracy on the substrate is regarded as a defective product that induces a tracking error. In addition, if the recording film thickness is not uniform or the reflectance of the reflective film does not reach a predetermined value, the individual is treated as a defective product that causes damage to the recorded data.
As a method for assuring the quality of optical discs, it is common to observe the amount of errors during writing and reading to and from the optical disc. This is because not only can manufacturing defects be discovered, but also manufacturing technology problems can be exposed and the cause can be estimated. Therefore, media manufacturing companies have implemented error measurement in shipping inspections of products.

On the other hand, even if the disc is treated as a defective product, errors are electrical signals, so it can be considered that the disc itself, which is a plastic plate that does not emit electrical signals, does not generate errors.
In this way of thinking, the source of the error is the electrical circuit of the drive, since the cause of the error is the faulty write operation or the faulty read operation of the drive device. Even if the individual disk has manufacturing problems, we believe that the error is caused by the action of the drive-side electronic circuit, or the interaction of these, induced by the disk individual with manufacturing problems. of.

Error measurement is not limited to what disk manufacturers do before shipment. In recent years, there are occasions when users themselves measure errors in optical discs after data is recorded to check whether there are any errors in the optical discs. This is because, due to the increase in capacity of optical discs, they have come to be used for backup purposes, and it has become necessary to manage the state of deterioration of optical discs for long-term storage backup purposes. In relation to this, the Japanese Industrial Standards (JIS) have standardized it as "Method for long-term storage of electronic documents (JIS Z6017)".

On the other hand, optical discs are often used as evidence in civil and criminal lawsuits. The analysis of litigation as evidence is called forensics. Analysis of optical discs as forensics is mainly concerned with the content of recorded data, but since the content of data recorded on optical discs has high evidential value, it may be subject to destruction of evidence.
Evidence analysis related to optical discs is generally considered to achieve its purpose by reliably reading the contents of data and evaluating the contents. In that case, the data output from the drive in which the optical disc is loaded is analyzed as being error-free.
The equipment and software applications used in such analysis methods are called digital forensic tools.
Originally, more than 99.9% of the data recorded on the DVD is error-free, and even if there are only about 0.1% or less errors, the error correction mechanism of the DVD is extremely powerful and the error is corrected. Therefore, it has been performed on the premise that 100% error correction is completed.
Therefore, typical conventional digital forensic tools do not have the function of efficiently analyzing the digital signal after various signal processings have been performed on the optical signal read from the optical disk before error correction.

What if the possibility of evidence destruction cannot be denied? Deletion of data files is the first aspect that must be considered as destruction of evidence in a lawsuit.
In this regard, in the analysis using conventional digital forensic tools, when the optical disk of the sample is loaded into an optical disk drive device connected to a personal computer, etc., and the data recording state is read, the data cannot be seen. However, analysis is performed to restore useful information by making full use of deleted data restoration application software.
Deleted data restoration targets that can be expected to be successful even with conventional digital forensic tools are text data and still images in JPEG format that are deleted data files. In this case, it was sometimes restored within the scope of functions attached to conventional digital forensic tools.
However, if the deleted data file is a moving image such as a security video image, restoration is difficult and there are few successful examples.
Based on such realistic circumstances, it has been considered reasonable to assume that the litigation case ended with the application of the deleted data recovery application software provided with the digital forensics tool.
In other words, in the past, although we did our best to the best of our abilities, we could never say that 100% analysis was achieved.

By the way, with respect to optical discs, errors that occur during the recording and reading process are observed over almost the entire area of the disc even though the total amount of recording is only 0.1% or less, even if there are some errors in each sector. It can be said that the distribution itself reflects the history of recording that occurred on the disc.
Conventionally, when examining the possibility of evidence destruction in optical discs, which are evidence in lawsuits, the viewpoint of examining the history of recordings has been omitted. I didn't get it.

In the present invention, as a measure to improve this, it is considered that errors occurring in the recording/reading process of an optical disk are observed over almost the entire area of the disk, and that the distribution of errors reflects the recording history of the disk. , Based on the error measurement, by investigating and analyzing what kind of error is in which place between the start point and the end point of the data area, we can find the peculiar situation at the time of recording reflected in the error. Invented a new analysis method and a device for implementing it that compensates for areas that cannot be seen with digital forensic tools, and as an application, individual identification of disks and certainty of detecting unauthorized duplication. Invented an optical disc with improved performance.

Japanese Unexamined Patent Publication No. 5-250688 Japanese Unexamined Patent Publication No. 6-296112

Japanese Industrial Standards JIS X6257 Standard Document "Methods for judging the quality of optical discs for long-term data storage and operating methods for long-term storage systems" 2017

Japanese Industrial Standards JIS X6256 Standard Document "Digital recording media for information exchange and storage - Test methods for estimating the lifespan of optical disc media for long-term data storage" 2019

Japanese Industrial Standards JIS Z6017 Standard Book "Method for long-term storage of electronic documents" 2013

Japanese Industrial Standard JIS X6249 "80mm (1.46GB/side) and 120mm (4.70GB/side) DVD Recordable Disc (DVD-R)" 2009

Japanese Industrial Standards JIS X6282 standard document "120mm write-once optical disc (CD-R) for information exchange" 2009

Japanese Industrial Standard JIS X6230 "Digital recording media for information exchange and storage -- 120mm single-layer (25 GB/disc) and dual-layer (50 GB/disc) BD recordable discs" 2017

Japanese Industrial Standards JIS X6231 "Digital recording media for information exchange and storage--120mm 3-layer single-sided (100 GB/disc), 3-layer double-sided (200 GB/disc) and 4-layer single-sided (128 GB/disc) BD Recordable Disc” 2017

Japanese Industrial Standards JIS X6255 Standard Document "Data migration method for optical discs for long-term data storage" 2019

Japanese Industrial Standards JIS X6252 "120 mm (8.54 Gbytes/side) and 80 mm (2.66 Gbytes/side) Dual Layer DVD Recordable Disc (DVD-R for DL)" 2011

International Organization for Standardization ISO/IEC29121 Standard 2021

International Organization for Standardization Standard ISO/IEC23912 Standard Corrected version 2006-04-01

International Organization for Standardization ISO/IEC30190 Standard 2021

International Organization for Standardization Standard ISO/IEC30191 Standard 2021

International Organization for Standardization ISO/IEC16963 Standard 2017

International Organization for Standardization ISO/IEC12862 Standard 2011

International Electrotechnical Commission Standard IEC60908 Standard 1999

The problem to be solved is that conventional digital forensic tools deal with the analysis of the digital area where errors are mixed until the signal read by the optical head of the optical disk drive device is digitized and error correction is performed. The point is that it was not possible.
Moreover, by applying the means invented to solve the problem, the conventional problem of difficulty in individual identification of copy disks having the same hash value can be solved.
In addition, the problem of finding counterfeit copies represented by so-called pirated copies is also solved.

Since the present invention exerts its power when the existence or non-existence of evidence destruction is demonstrated by verification, the gist of the principle applied at that time will be briefly described.
The DVD-R is recorded sequentially from the inner circumference without skipping. On the other hand, error measurement traces the entire area from the inner circumference address. Therefore, the time series of recording and the time series of error measurement match.
Moreover, since there is no way to delete the error distribution, even if the evidence can be destroyed by deleting the file or the like, if the error distribution is focused, the evidence of the existence of the recording session cannot be destroyed.
In other words, even if an act of concealment of evidence is carried out, the traces of the fact that "it happened" and its time series are preserved as traces on the error distribution and its time series.
Errors accompany data, so in the case of real-time recorded video data, the video recording time that existed before the file was deleted and the recording time of the error are the same with respect to the user area. Therefore, what percentage of the maximum writable amount of video data is on the disc should match what percentage of the error distribution is on the entire disc. If this does not match and the amount of playable videos is unreasonably smaller than the amount of error distribution, the amount of videos that do not match is deleted, exposing the possibility that evidence has been destroyed. . A group of drawings showing time-series results of error measurement that fulfills such a function will hereinafter be referred to as an error pattern chart.

A more specific configuration of the present invention will be described.
The present invention consists of ``001 - drive for error counting'' and ``002 - personal computer in which application program for creating an error pattern chart is installed'' (Fig. 1). The error counting drive is an optical disk drive (loaded with a disk to be inspected or an optical disk to be recorded/confirmed with an electronic watermark) having an error counting function. Further, in electronic watermarking using error patterns, the optical disk itself is a component of the invention, and the electronic watermark is embedded therein. Therefore, as a digital watermarking invention, a single optical disc on which a digital watermark is recorded can be a component. From these components, the error pattern chart of FIG. 2 is generated, analysis is performed, disc individual identification is performed, and digital watermark recording and reading are performed.
First, the measurement method is as follows.
(1) Count the number of errors with the error counting drive. As a count value, a set of a sector address (in hexadecimal notation) and an error number is output from the error measuring device as a file in csv format, and taken into a personal computer.
(2) Using the "error pattern chart creation application program" or similar error pattern chart creation application program installed in the personal computer, the range from the inner circumference address to the outer circumference address within the range of the user area The number of error occurrences for each address (recorded data amount in terms of graph notation) is graphed to create an "error pattern chart".
At this time, for example, within the range of standard functions of general-purpose spreadsheet application software such as Excel 2019, when trying to read a set of sector addresses and error numbers and create a graph, there is a problem that the hexadecimal number of the sector address cannot be displayed correctly. there were.
Therefore, in the present invention, if Excel is used, a dedicated program such as Excel-VBA is created to convert the sector address into the number of bytes consumed from the recording start point and display it on the chart. (Figure 2)
In addition, in order to investigate optical discs for data storage, which is the purpose of the present invention, and to appraise and verify whether evidence has been destroyed or forged, analysis should be performed focusing on the user area among the recording areas of the optical disc. Therefore, if the starting point of the created chart is the starting point of the user area, the analysis results will be clearer.
Therefore, when displaying the number of bytes consumed on the chart, after converting the sector address (hexadecimal) to a decimal number, the part from the 0 [hex] address of the sector address to the address of the start point of the user area is Subtract as an offset and create a chart to display with 0 at the start of the user area.
As an example, in the case of DVD-R, the starting point of the user area is 30000 [hex], and the offset amount after converting to decimal is 196608 [dec].
For use in appraisal, verification, etc., the chart is interpreted following the measurement.
(3) Data storage optical discs such as CD-R, DVD-R, and BD-R are recorded sequentially from the recording start point without skipping tracks or sectors, and error measurement is also performed over the entire range from the inner circumference address. to trace. Therefore, the time series of the recording and the time series of the error pattern chart match. For this reason, even if the data is corrupted and unreadable, as long as it can be traced, traces of the fact that there was a data recording session and its time series are included in the error distribution and saved (Fig. 3).
(4) A disc, which is a plastic plate that does not emit electrical signals, does not generate errors by itself, but rather it is the drive device that causes the error. If an operation unexpected from the normal writing operation is performed, such as trying to destroy the evidence during the writing operation of the drive device, it will also become an error source. Therefore, the error print chart also reflects write operation failures due to unexpected operations during recording. In addition, since the time series during recording matches the time series of the error pattern chart, the error pattern chart shows the time series of timings at which write operation failures occurred during recording. Since the interpretation of the error pattern chart relates to the recording state before error correction, it is possible to know the state of areas that cannot be seen with conventional digital forensic tools.
(5) Regarding the interpretation of the error pattern chart, the record history of the deleted file is as follows.
In optical discs for data storage such as CD-R, DVD-R, and BD-R, files once recorded can be deleted by selecting the format. Deleted files, especially video files, cannot be restored even with digital forensic tools in many cases. However, even if the recorded file is deleted, the trace remains in the error pattern. Therefore, even if the contents of the file cannot be read at all and the recording status of the file is unknown, by analyzing the error pattern chart, the recording history can be obtained from the optical disk in a state that cannot be analyzed with conventional digital forensic tools. can know. (Fig. 4)
(6) The method of discriminating individual discs by interpreting the error print chart is as follows.
If the recording conditions are different, the error pattern chart will reflect it. Therefore, even if the disk is an optical disk copied by so-called disk copying, and the disk has the same hash value and cannot be identified as the same by conventional digital forensics, the recording conditions For example, when copying by a personal computer and copying by a duplicator, or when the personal computer, drive device, and duplicator used for copying are different, this method can distinguish them.
If you change the drive and add an error, overwriting etc. easily occur at the joint of the session, so the recording timing fluctuates greatly and synchronization error is likely to occur. Therefore, in terms of error pattern analysis, the overwritten portion where such a large number of errors are counted is a characteristic portion to be subjected to error pattern analysis.
For example, in Figure 4 above, the four files were recorded as separate sessions in the order of (1), (2), (3), and (4), so there are large errors and stair-like error changes at the change of session. is occurring.
In particular, between sessions (1) and (2) and between sessions (3) and (4), there are error patterns that show sharp and large error changes. is due to "out of sync". Error changes due to out-of-synchronization will be explained in a later section, but such an error pattern facilitates identification of individual discs.
More specifically, the reliability of the absolute value of the error occurrence count is guaranteed by using a JIS standard (JIS-Z6017) measuring device for measuring the number of errors. Regarding the measurement device, the number of errors is a mechanism that outputs the number of errors as a csv. The JIS standard measuring device itself is intended to inspect whether the disc has deteriorated for the purpose of long-term storage of the disc, and is not intended to know the history of the disappearance of evidence due to the destruction of evidence or negligence. Therefore, an application program is added so that an error pattern chart for such purpose can be automatically created. The contents of the program will be explained by exemplifying an application program by Excel VBA in the embodiment described later.
(7) By using this property, it is possible to create an optical disc with a digital watermark, which will be described later.
The most important property of watermarks imprinted on banknotes and official documents used on a daily basis is that watermarks do not appear on copies of originals or cannot be copied.
Although the error pattern chart according to the present invention visualizes the distribution of errors in all sectors of an optical disk, errors are generated by physical laws and cannot be copied arbitrarily. The error distribution status of the original disc is not reproduced on the copy destination disc.
In other words, since errors cannot be copied, error patterns cannot be copied either.
Therefore, as Pattern 1, an unrecorded optical disk in which a visually conspicuous error pattern is embedded on the error pattern chart near the beginning of the user area. , and an optical disc with enhanced certainty for detecting unauthorized duplication. Data intended for original storage is recorded on an optical disc with an electronic watermark embedded near the beginning of the user area according to the present invention, and if the optical disc after recording is the original disc, the copy destination disc that is copied from this optical disc. Since the error pattern near the start of the user area is not copied, it is possible to detect that it is a copy. (Figure 5)
As pattern 2, before finalizing an optical disc on which data intended to be originally stored is recorded, as an electronic watermark according to the present invention, an error pattern chart is placed near the rear end of the user area. An optical disc in which a visually conspicuous error pattern is embedded is used to increase the certainty of detecting an unauthorized duplication containing a digital watermark according to the present invention. If the optical disc with the electronic watermark according to the present invention embedded near the rear end of the user area is used as the original disc, the error pattern near the rear end of the user area will not be copied to the copy destination disc. , can detect that it is a copy.
Furthermore, as pattern 3, as in pattern 2, an error pattern is added to the middle part of the user area as an electronic watermark according to the present invention for an optical disc on which the first half of the data originally intended to be stored has been recorded. After embedding a visually conspicuous error pattern on the chart, record the second half of the data originally intended to be saved. Since the error pattern near the middle part of the user area is not copied, it can be detected that it is a copy.
The digital watermarks of pattern 1, pattern 2, and pattern 3 can be combined and coexisted, and a plurality of each can be embedded.
The above is the most essential feature.

According to the present invention, for example, even when data on a moving image recording disk is damaged and cannot be restored, and analysis using a conventional digital forensic tool cannot be expected, the analysis using the error pattern chart can show traces of errors up to a percentage of the entire area. For example, if there is an error trace in 50% of the area of a 120-minute disc, it can be identified that it was recorded for 60 minutes.

Due to the above effect, when the disc is damaged and the data cannot be read, this method can be used to trace the disc and read the error. You can specify the time of the recorded minutes. For example, assume that a certain place is secretly photographed so as to fit on one disc per day. Assume an accident in which the power is turned off for some reason when the disk is exchanged, the recording ends abnormally, and all the moving images for the day cannot be reproduced. When this was evidence in the lawsuit, the reason why only the disc of the day was damaged and it became impossible to watch the video was that the party himself destroyed the evidence that there was an inconvenient record for one party. It is also assumed that it is argued that In such cases, it is assumed that conventional digital forensic tools may not be able to clarify the truth. You can specify the time of the paid minute. From this, it is possible to prove the truth that "the recording at that time does not exist".

If only a specific file is deleted on a single disk, the deleted file cannot be read as data, but the entire disk including the sector where the deleted file was located can be traced. can. You can count the number of errors by tracing the sector. From this fact, by using this method, even if only a specific file is deleted in one disc, the total capacity of the files that can be read at present and the number of sectors in which the existence of errors can be recognized. By comparing it with the total recording capacity consumed, it is possible to know how much of the file corresponding to the capacity has been deleted. (Fig. 6)

From one original disc, a clone-like disc having exactly the same file contents and structure may be created, and such copying work is called disc copy. Since the disc copied disc has the same hash value as the original disc, it is almost impossible to distinguish between the two discs with conventional digital forensics. Therefore, when optical discs for data storage such as CD-Rs, DVD-Rs, and BD-Rs are treated as evidence in litigation, the optical discs as evidence and the optical discs that are disc copies thereof are considered as evidence. It is considered to have equal probative value if the formalization procedure is properly carried out.
However, even if conventional digital forensics cannot distinguish between the original disc and the clone disc, both discs can be distinguished by comparing the error pattern charts according to this method. (Fig. 7)
Fig. 7 shows error pattern charts for (1), (2), and (3) when copying three discs from the original disc and labeling them as (1), (2), and (3). However, since the write drive for each copy is changed, it is possible to identify each change by comparing and contrasting each error pattern chart.

A JIS-compliant disc inspection machine, such as the TEAC Co., Ltd. product model number: DK-5000S-0A, comes with a dedicated application that outputs the measurement results as numerical values in a csv file, but an error pattern chart is created. not. In the present invention, an application program with a function of automatically creating an error pattern chart was created as an embodiment to be described later. According to this, the error patterns of a plurality of discs can be displayed on one chart at the same time for comparison. It contributes to the clarification of the recording history of the disc.

An optical disc with a digital watermarking function can be realized by positively utilizing the disc recording history discriminating function based on the error pattern according to the present invention.
Arbitrarily visualized in advance on the error pattern chart at the recording start portion of the user area of an unrecorded optical disc, the middle portion of an optical disc during data recording, or the vicinity of the trailing end portion of a recorded optical disc before finalization. By embedding an electronic watermark composed of a characteristic error pattern, it is possible to provide a disc authenticity function and other functions for discriminating discs from other discs.

FIG. 1 is an explanatory diagram of a personal computer (installed with an application program) and an optical disk drive having an error counting function (loaded with a specimen disk or an optical disk to record/confirm an electronic watermark), which are the components of the present invention. FIG. 2 is an explanatory diagram of an error pattern chart according to the present invention. FIG. 3 shows that the time series of recording and the time series of the error pattern chart in the optical disk for data storage according to the present invention match, so the traces of the fact that there was a data recording session and the time series are in the error distribution. FIG. 4 is an explanatory diagram of the concept of being included and stored; FIG. 4 is an explanatory diagram of knowing the history of recording from the property that even if a recorded file is deleted, its trace remains in the error pattern in the interpretation of the error pattern chart in the present invention. FIG. 5 is an explanatory diagram of the error pattern digital watermark in the present invention. FIG. 6 is an explanatory diagram showing that even when only a specific file is deleted, it is possible to know how much of the deleted file has been deleted in the present invention. FIG. 7 is an explanatory diagram of a method for distinguishing an original disc and a clone disc of a disc-copied disc according to the present invention. FIG. 8 shows the error generation situation of the actual optical disc, which is the premise of the embodiment of the interpretation of the error pattern chart according to the present invention. It is explanatory drawing of becoming. FIG. 9 shows the results of error measurement over the entire area of a commercially available DVD. FIG. 10 is an error print chart of the test disk. FIG. 11 shows an example of a PLL circuit of an optical disc drive. (Quoted from Japanese Unexamined Patent Publication No. 5-250688) FIG. 12 is an experimental phase modulator. (Quoted from Japanese Unexamined Patent Publication No. 6-296112) FIG. 13 is an ECC block of DVD-R. (Quoted from Japanese Industrial Standards JIS X6249 standard document "80 mm (1.46 GB/side) and 120 mm (4.70 GB/side) DVD recordable disc (DVD-R)" 2009) FIG. 14 shows the allowable overwriting range of JIS standard DVD-R. (Quoted from Japanese Industrial Standards JIS X6249 standard document "80 mm (1.46 GB/side) and 120 mm (4.70 GB/side) DVD recordable disc (DVD-R)" 2009) FIG. 15 is an error pattern chart at the time of DVD-R additional recording. (Table 1-1) (Table 1-2) (Table 1-3) (Table 1-4) (Table 1-5) (Table 1-6) (Table 1-7) (Table 1-8) Table 1 -1 to Table 1-8 are the flow chart of the application program according to the embodiment. (Table 2) is the source code of the application program according to the embodiment. In addition, based on the change of the detailed rules pertaining to the application, in the description in the text of this specification, the images represented by so-called circled numbers in Figures 1 to 15, Tables 1 and 2 are (1), (2), (3), etc. are replaced with numbers in parentheses. Regarding the source code of the application program in List 2, regarding the parts with bracketed numbers such as (1) and (2), the so-called circled numbers in the corresponding image of List 1 are the program code. In practice, if the program is operated by replacing the numbers with circles, the operation will be the same as the operation of the application program confirmed by experiments etc. at the time of this application.

Until now, the analysis of optical discs has used a method of using digital forensics to analyze the data output from the drive in which the disc is loaded, assuming that the data is error-free. About 99.9% or more of the data recorded on the DVD is error-free, and even if there are only about 0.1% or less errors, the DVD error correction mechanism is extremely powerful and most of the errors are corrected. Therefore, it is appropriate to perform digital forensics on the premise of 100% error correction completion. Even if the data cannot be seen or useful information cannot be recovered even if the deleted data recovery is performed, what should be done with digital forensics assuming that analysis of 99.9% or more of the area has been completed by digital forensics It is often reasonable to assume that the
However, when 0.1% of the analysis area remains after the analysis of 99.9% of the area is completed, it may be necessary to work on that area. Errors that occur during the recording and reading process are not more than 0.1% of the total recorded amount, but even if there are some errors in each sector, they are observed over almost the entire disk, so the distribution itself is is likely to reflect the recording history that occurred on the disc.
In the present invention, by examining the error distribution, as a breakthrough to deal with the remaining 0.1% area, by analyzing the error occurrence as the interaction between the optical disk disk and the drive, digital forensics It is implemented as a new analysis method that compensates for areas that cannot be seen.

It has become known that special consideration is required for optical discs for backup purposes, and the Japanese Industrial Standards (JIS) have standardized them as ``Methods for long-term storage of electronic documents (JIS Z6017)''.
It was first standardized in 2006 and revised in 2013, but its gist is based on the assumption that (1) optical discs have a limited lifespan, and (2) digitally recorded data have strong error correction. (3) Perform an inspection over the entire area where the data is recorded regarding the error situation when the disc is first recorded, (4) The number of errors in the entire optical disc surface is the standard for initial quality inspection by JIS. (5) Approximately 5 years after that, inspect the entire optical disc surface for errors in a periodic quality inspection, and JIS stipulates it as a standard value for periodic quality inspection. It requires that the maximum value be smaller than the value, and if these are not met, the disk will be recreated.
The JIS standard (the same kind of standard has been established in the international standard) stipulates the inspection of the entire area, and the standard for acceptance of the inspection is the maximum error value within the surface of the optical disk.
In response to this, inspection devices for inspections defined in the standards have come to appear on the market.
The present invention uses such a JIS standard inspection device to carry out measurements, and examines what kind of error is at what location from the start point to the end point of the data area. It is implemented as a new analysis method that analyzes the error occurrence as the interaction of

In addition, in the present invention, the time-series results of error measurement are provided so as to facilitate comparison of error patterns on a disc to be analyzed with error patterns on a reference disc, or to facilitate comparison of error patterns on a plurality of discs. It is implemented as an analysis method using an error pattern chart based on a group of drawings showing .
Furthermore, since the error pattern chart reflects different recording conditions, even if the disk is an optical disk copied by a so-called disk copy, and the disk has the same hash value and cannot be identified as the same by conventional digital forensics, If the recording conditions are different, for example, if copying is done using a personal computer and copying is done using a duplicator, or if the individual personal computer, drive device, or duplicator used for copying is different, this is implemented as a method of distinguishing between them.
In addition, by applying the principle of the present invention and utilizing the property that error patterns cannot be copied because errors cannot be copied, it is implemented in the form of an optical disc with a digital watermark.
By embedding a digital watermark in advance, the error pattern near the start of the user area is not copied, so the optical disc can be recognized as a copy.
After the data is recorded, the digital watermark according to the present invention is embedded in the vicinity of the rear end of the user area, and the optical disc is embodied as an optical disc with enhanced certainty of detecting unauthorized duplication.
After embedding the electronic watermark according to the present invention in the middle part of the user area in which the data is recorded halfway, by recording the latter half of the data originally intended to be stored, the electronic watermark is placed near the middle part of the user area. is implemented as an optical disc embedded with

This embodiment demonstrates the present invention as a method of analyzing the digital area, which has not been analyzed in the past, until the signal read by the optical head is digitized and subjected to error correction, and the analysis method using the error pattern chart. It is an example.
An example of a method for interpreting an error pattern chart of an optical disc, which constitutes the present invention, will be described below.
When writing is performed a plurality of times on the same disc up to the recording end portion of the optical disc, the first recorded session is the first session, and the nth recorded session is the nth session. When there are a plurality of sessions, particularly when a plurality of write drives are typically used, the error occurrence conditions change for each session and are reflected in the error distribution.
If there is a write error or abnormal termination in the last session, none of the files recorded in that session may be unreadable, or files recorded in previous sessions may not be readable. It is possible to trace the affected sectors and find out the error occurrence status of the traced sectors.
One of the important properties related to the present invention is that when the error distribution is analyzed, a non-uniform error distribution state for each individual DVD is observed.
A DVD-R must be formatted when it is first used, and if the format for additional recording is selected at that time and the formatting is performed, files can be additionally recorded at a later time on the disk once recorded. You can also delete the recorded files. In this case, even if the file is erased, the fact that the file has been erased is recorded in the file management area. do not.
Therefore, even for deleted sectors of a file, the error distribution state before file deletion is reflected in the error distribution state after file deletion.

Observing the base surface of an actual CD-R or DVD-R, it is normal to be able to see a concentric circular pattern. It looks folded. It is rare that the pattern cannot be seen.
The amount of error generation also varies from place to place and from session to session. If an error occurrence situation is observed and expressed as a pattern, a concentric pattern reflects the actual situation.
If we think about subtracting only the data part from a state in which data and errors are mixed, we can think of the distribution of errors as a pattern that changes in a donut shape.
(Figure 8)

In the case of a DVD-R in which the entire area is not completely written at once, but is additionally written at any time, the error distribution changes around the recording start/recording end, which is the boundary between recording sessions.
Even if the session ends abnormally, it is reflected in the error distribution of the end location.
Therefore, even if some kind of accident occurs in DVD-R writing, etc., and some or all of the files become unreadable, it is possible to estimate the situation by reading the error distribution that reflects the abnormal termination of the session based on the accident. be a clue to.

FIG. 9 shows the results of measuring errors in the entire area of a commercially available DVD. This is a measurement of a single-layer DVD.
The error rate is 100 or less over the entire disc (*error rate is 0.033% for 8 ECC blocks (182 x 208 x 8) when the value is 100), which reflects the recording method of DVD-ROMs manufactured by stamping. It can be said that
When a DVD-R is created in a write-once format, once recorded files can be deleted. If all the recorded files are deleted, the file will not exist on the computer's explorer, but if you measure the error of the entire DVD-R, it will be assumed that the sector where the file was recorded before deletion could not be read as data. Even the error when recording it remains.
Since there is no file, it is the trace result of the sector rather than the result of error measurement, but if you show the recorded file, the order of recording, the explorer display, etc. or an explanation, it will be a drawing that can explain the error distribution situation.

FIG. 10 shows an error pattern chart of the test disk.
The target is a DVD-R on which all files are deleted after recording four image files for testing.
The lower center of the figure is the display of the explorer of the personal computer, but since all the files have been deleted, nothing is displayed. The lower right part of the figure shows a recorded video file (part of a movie), which was recorded as separate sessions in the order of (1), (2), (3), and (4), and then deleted all at once. (1) is 6 minutes, (2) is 10 minutes, (3) is 14 minutes, and (4) is 18 minutes. The upper part of the figure shows the error measurement results for the entire disk. The lower left part of the figure is an enlarged view of a part of the upper part of the overall error diagram, showing error patterns in sectors where files (1), (2), (3), and (4) were recorded.
Unlike errors in the entire disk area of commercially available DVDs, the error generation conditions differ depending on the location, so the graph is a stepped graph.
Large spike-like errors occur between (1) and (2) and between (3) and (4).
This error is not caused by a defective disk or the like, but is an error due to out-of-synchronization caused by a different time reference from the previous session when recording is started in a new session. Item will be described later. Since it serves as a marker for the seams between sessions, it is easier to analyze when a synchronization error has occurred.
In this way, even if the disc does not contain any files at all, it is possible to find traces that the files were recorded in four sessions by analyzing the error pattern chart.
A completely data-unreadable DVD-R cannot be analyzed by digital forensics. Even if security camera images recorded on a DVD-R are deleted, it is often difficult to restore them by digital forensics.
Even under such circumstances, if the disc is not physically damaged, it can be traced. If it is within the scope of making evidence for the purpose of recognizing the fact that the session was terminated abnormally, it can be expected to supplement the areas outside the scope of conventional digital forensics analysis.

To summarize the idea of the error pattern analysis method, conventional digital forensics cannot proceed any further if the file cannot be read from the disk being analyzed or cannot be restored.
On the other hand, even if the file can't be read, the session still exists, and that session will always have errors, more or less.
Since the distribution of errors changes for each session, if an event such as an accident occurs during recording on the disc and the session ends abnormally, this will be reflected in the error occurrence state, and the disc recording start point ( 0.0GB point) to the maximum recordable point (4.38GB point for a write-once formatted DVD-R), and charting it shows that the error pattern that reflects the abnormal session termination due to an accident caused an error distribution. events can be inferred.
Therefore, the analysis method using the error pattern chart according to the present invention can be used to analyze an optical disc on which an accident occurred during writing, which could not be analyzed by conventional digital forensics.
As a procedure, (1) assume a conceivable situation and reproduce the same situation, (2) perform writing to the simulation DVD-R under the situation, and (3) error distribution of the simulation DVD-R. Measure the situation, (4) chart and visualize the obtained error distribution (error pattern chart for comparison), and (5) measure, chart, and visualize the error distribution on the DVD-R to be analyzed. (error patterns to be analyzed), and by comparing the error patterns (4) and (5), it is possible to find traces that can be used to estimate the event that occurred.

As for the first embodiment, it is possible to expect the effect of contributing to the factual inference in the appraisal work as follows, by performing the analysis using the error pattern chart in relation to the one-time recording type optical disc.
(1) Even if it is claimed that the file that should have been recorded has disappeared, digital forensics cannot find the evidence and the deleted data cannot be restored. If a pattern chart is created and it is recognized that the current readable file capacity and error patterns match, it is presumed that there is no evidence that the recorded file has been deleted.
(2) If the observed error pattern does not match the current amount of readable files, the possibility of file deletion may be inferred. For example, in the case of FIG. 10 mentioned above.
(3) As an application, for example, in the case of FIG. 10, the person who recorded and deleted the files deletes the files (1), (2), (3), and (4) after recording, and then deletes the fifth and subsequent files. If you state that you have not recorded it, you can support it with an error pattern chart.
(4) If an uncorrectable error, such as an extremely large error pattern, has occurred in the final recorded portion of the last session, it can be assumed that the session ended abnormally due to an accident such as forced interruption of writing. Sometimes.
(5) An error pattern chart such as the example given up to the previous section can be obtained from the originals recorded in separate sessions. On the other hand, with regard to copies, regardless of whether they are copies using a personal computer or a duplicator, if the starting point to the end point are recorded at once, the appearance of the error pattern for each session will differ from that of the original. Therefore, the original and the copy can sometimes be distinguished from each other by the error pattern.
(6) After creating the original in the write-once format and turning it into evidence, if you tamper with it by adding a new file using another computer, etc., the error pattern chart shows that the error pattern in the tampered part is It can be used to detect and prove tampering, as there are steps and large error patterns appear at seams.

Example 2 is an example of a method of analyzing errors caused by out-of-synchronization.
As mentioned above, the optical disc itself does not generate errors, errors are caused by bad write or read operations of the drive device, and the source of the error is the electronic circuit of the drive.
And when the electronic circuit of the drive reads the data recorded on the optical disk, if it cannot synchronize with the reference clock pulse when writing to the optical disk, it will be an error.
A digital media that rotates a disk by a motor is required to (1) keep a fixed number of revolutions and (2) synchronize the clock pulse with the signal read from the rotating media. A method called PLL (Phase Lock Loop) is used when not only the number of revolutions but also synchronization is required. This is done by installing a reference quartz-type oscillator inside the equipment, integrating an angle detector that generates a pulse at each constant rotation angle in the rotating body, and matching the phase of the reference quartz and the phase of the angle detection signal. By doing so, it is intended to obtain the rotational speed accuracy equivalent to the accuracy limit of the resolution of the angle detector.
In optical discs, the phase of the signal output from the head that reads the disc, that is, the phase on the disc side, is used as a reference, and the phase of the clock pulse of the data reader is adjusted to this. In this way, only one clock pulse is used as a phase reference, so as long as the phases are matched, no error will occur.
Although the motor that rotates the optical disc is highly accurate, it is unavoidable to have rotation irregularities of at least 0.1%. The pulse fluctuates accordingly. In addition, since the phase is unstable when the disk starts to rotate, it is necessary to add a circuit that makes the phase of the clock pulse of the data reader follow the phase of the signal output from the head that reads the disk, that is, the phase on the disk side. . A PLL circuit is also used here.
FIG. 11 shows an example of a PLL circuit of an optical disk drive. (Quoted from Japanese Unexamined Patent Publication No. 5-250688)
The signal from the optical pickup is like a synthesized sine wave whose frequency changes and whose harmonic components also fluctuate ("TE" in the figure), as shown in the signal schematic diagram at the bottom of the figure.
For example, if a small mold grows on the surface of the optical disk and only some of the pits cannot be read, part of the signal is lost as indicated by TE in the figure. When creating a clock pulse from this signal, if digitization by simple binarization is performed, the clock pulse will change depending on whether there is a missing signal or not, as shown by "TC" in the figure, resulting in an error. cause.
It is the PLL circuit that prevents this, and its operation is to generate a clock pulse based on the phase of the rising portion of the binarized and digitized signal, and generate the self-generated clock pulse and the clock pulse from the optical pickup. When there is a phase shift in the signal, feedback is applied to match the phase of the self-generated clock pulse to reduce the phase difference.
The PLL circuit installed in the optical disk drive is designed to operate in situations where the basic clock pulse frequency is expected to change significantly (at a far away address), taking into account the unique nature of the optical disk drive, in which the signal may occasionally drop out. The variation width of the clock pulse frequency is limited when reading data continuously, except when trying to access a file. Although the phase change is designed to be within about 20% during steady rotation, the phase change margin is sufficient for disc rotation unevenness.
In such a design example, when there is a phase change of more than 20%, it is assumed that there was a missing signal, and the changed phase is not tracked, and the previous reference phase is maintained. By generating a clock pulse, the desired reading timing is maintained.
This is devised so that an error due to one missing signal will not lead to an error in reading the next signal.

The biggest reason why many errors still occur is the phenomenon of "out of synchronization" in the PLL circuit.
Loss of lock occurs when a large event occurs that exceeds the phase change margin of the design specification of the PLL circuit.
One of the causes of out-of-synchronization is assumed to be that signals cannot be read over a wide area when the reflection film rusts or the recording film deteriorates due to aging of the disk. In this case, the signal to follow the phase of the clock pulse is interrupted for a long period of time, and the phase of the clock pulse is greatly shifted without realizing it. This is a form of out-of-synchronization, and all data after the out-of-synchronization will be in error.
In addition, even when the rotation unevenness increases due to aging of the drive motor, if there is a variation exceeding the tracking range of the PLL circuit, loss of synchronization will occur.
As another example, if the C/N ratio (carrier/noise ratio) of the signal deteriorates, the phase shift occurs repeatedly due to noise, and the phase shift continues to exceed the design margin. , can get out of sync and cause an error.
These phenomena can be confirmed experimentally. FIG. 12 shows an experimental phase modulator. (Quoted from Japanese Unexamined Patent Publication No. 6-296112)
When the reference clock pulse of the drive is Φ0 in the same figure, this circuit gives SA in the same figure as a simulation signal of rotation unevenness and noise. and SP'.
By inputting the phase-shifted signal to the PLL circuit in this way, it is possible to confirm how out-of-synchronization occurs when the phase change exceeds the design margin.

In order to compensate for the limitation that DVD-R can only be written once, it is standardized to be a write-once format (multi-session) so that files can be added and deleted as needed with the same ease of use as USB memory. Supports above.
However, if the drive that performed the first writing is different from the drive that performed the second, third, etc. writing, trouble is likely to occur.
When additional recording is performed using different drives A and B, the recording of writing by the A drive and the recording of writing by the B drive are close to each other in a place such as a file management area. Since the optical pickup determines the reference threshold value for binarization of the signal according to the signal intensity of the deeper writing among A and B, the signal of the shallower writing is suppressed and the C/N ratio deteriorates. .
If a loss of synchronization occurs due to deterioration of the C/N ratio and a large number of uncorrectable errors occur, it may become impossible to read the file itself.
Drives with deep writing outside the standard may also be on the market as products. In another drive B machine, there are sometimes troubles such as being unable to read files that should have been written by the B machine.

The error pattern caused by the write timing deviation of a plurality of drives as described above has remarkable characteristics.
The powerful error correction mechanism of DVD is derived from the fact that horizontal and vertical parities are provided in the data format, and error portions can be corrected by parity checks. JIS standard "The number of PI errors shall be the number of rows in an ECC block with at least one byte error. In any eight consecutive ECC blocks, the total number of PI errors before error correction shall be 280 or less." The following is a brief description of the stipulations.
Data and parity are error-corrected in units called ECC blocks, and one ECC block is composed of 208 rows each having a length of 182 bytes.
172 bytes of 182 bytes in one row are data, and the last 10 bytes are PI (internal parity = inner code parity).
192 lines of 208 lines are data, and the last 16 lines are PO (external parity=outer code parity).
FIG. 13 shows an ECC block of DVD-R. (Japanese Industrial Standards JIS X6249 standard document "80 mm (1.46 GB/side) and 120 mm (4.70 GB/side) DVD recordable disc (DVD-R)" 2009)
An error of 1 byte or more in one row in a specific ECC block is called a PI error (PIE), which can be corrected by internal parity, and up to 280 errors can be corrected.
A state in which one row in one ECC contains an error even after error correction by internal parity is called a PO error (POE) or PIF error. Although this is a severe error, it may still be correctable by external parity in this situation.
An error that cannot be corrected by using external parity is called a POF error, and data loss occurs due to an error that cannot be corrected.
DVD-R error measurement uses what is called a PI/PO test, which counts the number of errors corrected in one ECC block.
A common test is to count the number of errors in eight consecutive ECC blocks, called PI-SUM8.

When writing is performed by alternately using the A drive and the B drive, the clock pulses emitted from the quartz oscillators inside the devices of both drives cannot be synchronized.
Similarly, the optical heads of both the A drive and the B drive cannot be moved in exactly the same way.
Therefore, the recording start timing cannot be matched, and a phase shift occurs when moving from the area written by the A drive to the area written by the B drive. If the phase shift is large, it cannot be followed. Loss of synchronization occurs.
Also, in a write-once format, using a different drive for each session can result in the end of the previous recording and a slight overwrite.
When the overwritten portion is measured with an error measuring instrument, many errors are counted, but since the data portion is not recorded and is not subject to file output, errors in this portion are not counted for quality assurance purposes.

Such slight overwriting is inherent in the JIS standard and is considered permissible under the standard.
Taking the DVD-R as an example, in JIS X6249, which defines its characteristics, when a new session is started after closing a session, the end portion of the recording of the previous session is recorded in the linking sector, which is the connecting portion. It is a rule that the start of the recording of a new session may come within 1 byte before or after 1 byte. FIG. 14 shows the allowable overwriting range of JIS standard DVD-R.

However, in terms of error pattern analysis, the overwritten portion where such a large number of errors are counted is a characteristic portion to be subjected to error pattern analysis.
FIG. 15 shows an error pattern chart at the time of DVD-R additional recording.
If different drives are used for each append session, overwriting is likely to occur at the joints as mentioned above, so the joints are not data and are not subject to error correction, but are displayed as large errors in the notation. In this portion, the phase of the overwritten portion fluctuated beyond the follow-up limit of the PLL circuit, causing loss of synchronization and causing a large error.
In addition, since the average value of the error measurement values in the data area also differs for each session, the error pattern chart is displayed in steps.
Incidentally, when analyzing DVDs and Blu-ray discs having a multilayer structure, stair-like error patterns are observed at the seams of the layers, so it must be distinguished from overwriting.

With regard to the second embodiment, the effect of contributing to the inference of facts in appraisal work can be expected by performing an analysis using an error pattern chart for a one-time recordable optical disc.
A. Large spike-shaped error pattern If a very large spike-shaped error is observed in the error pattern chart, write session termination (including abnormal termination) or buffer underrun at that location will be prevented. A temporary write interruption may have occurred and a new write has occurred.
B. Stepped error pattern If the error pattern chart is in a stepped pattern corresponding to the total size of the session assumed from the file size that can be read from the disc, if it is a single-layer DVD/BD, the session It may have been recorded using a different drive each time.
C. Exceptions for multilayer DVDs and multilayer Blu-ray , the error pattern chart becomes a staircase pattern.
However, if the step position does not hit the seam of the layers, there is a possibility that recording was performed using a different drive for each session.

Example 3 is an example of an electronic watermark that performs individual identification using the nature of an error that occurs due to out-of-synchronization, and an optical disc that allows individual identification.

Out-of-synchronization can be intentionally introduced. For example, experimentally, a DVD-R disc on which a file was recorded as the first session with an external drive WH16NS58DUP manufactured by LG HLDS was temporarily terminated and the disc was removed. When recording files using the attached drive DVR-S21DBK, there is a very high probability that you will get a large spike error pattern caused by out-of-synchronization between the first and second sessions. can be done.
Even with other drive combinations, if you change the drive for each session and record, you can often get a large spike-like error pattern.

Using this, immediately after formatting the DVD-R, (1) determine the size in advance and record a small file, (2) end the session, (3) switch to another drive, and create a new drive. Record a small file as a session and (4) end the session. With this process (1) to (4), each time a new session is recorded by changing the drive, one artificially large spike-like error pattern can be obtained, and multiple new sessions can be recorded. By repeating the process multiple times, a plurality of large spike-like error patterns can be obtained by concentrating on a portion near the inner periphery of the disk immediately after formatting.
Although the probability of occurrence of a large spike error is not 100%, for example, if the above operation is performed with the intention of generating 8 large spike errors in succession, 5 or more large spike errors will occur experimentally. I am getting an error of

Out of sync can be intentionally prevented. For example, experimentally, using a Matsushita DVD drive UJ8E2 built-in DVD drive for ThinkPad W540, a personal computer manufactured by Lenovo, a DVD-R disc on which files were recorded as the first session, once the session was terminated, the disc was ejected, and 2 In the second session, when the file was recorded using the DELL PC E6540 built-in DVD drive, there was a very high probability that there was a large spike between the first and second sessions. No error pattern occurs. Depending on the drive design, out-of-sync can be intentionally prevented.

Taking advantage of this, immediately after formatting a DVD-R, a session that intentionally causes loss of synchronization and a session that intentionally prevents loss of synchronization by concentrating on the part near the inner circumference can be freely combined. At regular intervals, large spikes of errors can be generated or not generated.
In this way, if it is possible to artificially create the arrangement of large spike-like errors, for example, by setting 8 sessions x 4 groups from the innermost circumference as such an artificial out-of-synchronization error generation region, it is possible to reliably Since a large spike-like error can be observed for 4 groups, an identification code of at least 4 bits length can be recorded.
If different ID codes are attached to discs, it will be 4 bits, that is, 16 kinds of identification codes.
It can also be a shorter or longer identification code instead of 4 bits.
Hereinafter, such a method of attaching an identification code is referred to as error pattern electronic watermarking.
FIG. 5 mentioned above is an embodiment of the error pattern digital watermark.

The error pattern digital watermark can be recorded immediately after formatting before data is recorded, or it can be recorded in the outermost periphery immediately before finalization after all recording is completed. It is also possible to record at an intermediate point between the innermost circumference and the outermost circumference. As for the use of recording at the intermediate point, when recording a plurality of days on one disc, by recording such an error pattern digital watermark at the end of recording every day, it is possible to clarify the boundary of the recording date. can be considered.

Since the error pattern electronic watermark is removed as an electromagnetic signal after error correction, when the original disk on which the error pattern electronic watermark is recorded is copied, the error pattern electronic watermark is not reproduced on the copy disk.
By using this property, it is possible to distinguish between the original and the copy.
This property does not depend on the file to be recorded, and even if the hash value of the file is the same, the original and the copy can be distinguished.

As described above, by giving an error pattern digital watermark before recording a file to be saved in advance, an optical disc that can be individually identified can be realized.
Also, by adding an error pattern digital watermark after recording a file to be saved, an optical disc that can be individually identified can be realized.

Example 4 relates to a method of identifying discs with the same hash value by error prints.
As for whether the target disk is an original or a copy, conventional digital forensics had no choice but to conclude that as long as the disk image is the same, the hash value is the same and it is indistinguishable. Also, there was almost no discussion about the significance of individual identification and classification of disks with the same hash value.
Even so, even if the hash value of the disk image is the same, it is not possible to identify or identify the individual disk, because the replacement of the original or duplicate due to the fabrication, replacement, or damage to the evidence in the litigation case can become a point of contention in the court. The classification method has a meaning of existence, and in this respect, it is desirable to supplement conventional digital forensics.
Furthermore, when there are a plurality of discs that are all copied pirated copies in the production of pirated copies that violate the copyright law, it is possible to classify them according to the difference in error pattern. As a result of the classification, it is possible to distinguish between the discs mass-produced by the duplicator and the small number of discs that are the original discs of the pirated copies, and it is expected that this classification will contribute to the purpose of identifying the perpetrators of the pirated copies.
By using this error pattern analysis method, even if the hash values are the same, it is possible to distinguish between the original and the copy by observing the error distribution.

As a widely used disk duplication method, a computer is used to download a disk image of the original disk using duplication software, and when the disk image is copied to an unused disk, the hash values of the files are made the same. A copy is obtained.
Error patterns on duplicates have not been mentioned much so far, but on original discs, step-like changes in error patterns can be seen at the joints between sessions, but on copy discs this is not the case.
In some cases, the copy has significantly fewer errors and is of higher quality than the original.
Disc images tend to be misunderstood as copying and reproducing all kinds of information on the original disc, but this is the result of embodying the fact that this is not the case.
A disk image is just a copy of a logical block, and it is impossible to copy or generate errors that occur as natural scientific physical phenomena and are corrected when they occur.
In this case, when reading the image of the original disc, all the errors on the error pattern chart have been corrected, creating an error-free disc image. When data is written to a copy disk, since the data is written from the beginning to the end at once, there is no overwriting, and large errors are less likely to occur.
By using the method according to the present invention for identifying discs with the same hash value based on error patterns, it is possible to read the situation in which the recording history is reflected in the error patterns. It is possible to distinguish a copy disc from which no synchronization error has occurred, or to distinguish from a copy disc which has no stepped error pattern change.

Also, according to experiments, even if the same drive is used to create a copy from the same original disc, if the recording history is even slightly different, the error pattern will be different and the disc image with the same hash value will be recorded. may also be able to identify individual discs. For example, when copying a disk using the copy function of a personal computer and copying software, it is possible to select the option of using or not using an HDD. Depending on whether this option is used or not, the error pattern of the copy may change.
By using the method of identifying discs with the same hash value by error patterns according to the present invention, it is possible to read the situation in which the recording history is reflected in the error patterns. Even if the recorded disk images are the same, the individual can be identified by analyzing the error pattern.
FIG. 7 described above is an explanatory diagram of an embodiment of a method for discriminating discs having the same hash value by disc copying by error patterns.

In Example 5, when data on a moving image recording disk is damaged and cannot be restored, and analysis using a conventional digital forensic tool cannot be expected, the analysis method using the error pattern chart of the present invention is used to find traces of errors in the entire area. %, can be used as verification in lawsuits, etc., and can be used as evidence.

As can be seen from the fact that DVD-Rs for TV recording are sold as "120 minutes," etc., the total recording time for the entire area per disc is determined by the settings such as the recording mode. If it is possible to measure the percentage of error in the recording area with respect to the maximum recording capacity of the disc, it does not require a difficult interpretation of how many minutes have been recorded, and it can be said that "60% error on a disc set to record 120 minutes in all areas". Since there is a trace, it can be determined almost unambiguously that 72 minutes of recording was done before the data was destroyed.

Under the law of litigation, such measurements are of a nature that can be perceived by the actions of the five senses, faithfully recorded, and read, and therefore can be carried out as verification.

Example 6 relates to an apparatus used for analysis using an error pattern chart.

JIS standard measuring equipment whose reliability is guaranteed should be used for measuring work when there is a plan to use it as evidence in court.
Currently available JIS standard inspection equipment traces the disk from the innermost circumference and counts the number of errors for each error correction block. DK-5000S-0A manufactured by TEAC, which is one of such inspection devices, outputs the sector address and the number of errors as a csv format file for the error count result, so the numerical value can be accurately grasped. , the chart is not created.
In this method the conclusion is affected by where on the disk the error resides. An error pattern chart makes it easier to see it, and it is appropriate to create it as a line graph using Excel.
However, since disk sector addresses are specified in hexadecimal, there is a trick to creating charts in Excel. Excel does not handle hexadecimal addresses well, and when reading them as numbers, it treats "E" in hexadecimal 0123456789ABCDEF as an exponent. Even if you change various settings of Excel, it will not be solved as long as it reads "E" as a number.
To solve this problem, it is necessary to read the hexadecimal address as a character string and then convert it to a decimal number.
In this embodiment, as an apparatus for creating an error pattern chart, an application program for generating an error pattern chart from an inspection machine that outputs hexadecimal addresses and error numbers in a csv format file is exemplified.

Table 1 (divided into Tables 1-1 to 1-8) shows a flowchart of an exemplary application program.
Table 2 shows the source code of the exemplary application program.

（表１－２）

（表１－３）

（表１－４）

（表１－５）

（表１－６）

（表１－７）

（表１－８）

An example of these lists is Excel that creates an overwritten error pattern chart for comparison from csv files (extension is txt) of the error measurement results measured by the application attached to TEAC DK-5000S-0A for 8 times. This is the source code of the VBA application program.
(Table 1-1)

(Table 1-2)

(Table 1-3)

(Table 1-4)

(Table 1-5)

(Table 1-6)

(Table 1-7)

(Table 1-8)

(Table 2)

Sub Macro02 Whole area inspection ()


Sheets("Sheet3").Select

ChDir "D:\ExcelMacro4ErrorChart"
Workbooks.OpenTextFilename:= _
"D:\ExcelMacro4ErrorChart\driveD\ExamAll01Times.txt", Origin:=932 _
, StartRow:=1, DataType:=xlDelimited, TextQualifier:=xlDoubleQuote, _
ConsecutiveDelimiter:=False, Tab:=False, Semicolon:=False, Comma:=True _
, Space:=False, Other:=False, FieldInfo:=Array(Array(1, 2), Array(2, 1), _
Array(3, 1)), TrailingMinusNumbers:=True
Columns("A:C").Select
Selection. Copy
Windows("Reproducibility test 8 times.xlsm").Activate
ActiveSheet.Paste
Windows("ExamAll01Times.txt").Activate
Application. CutCopyMode = False
ActiveWorkbook.SaveAs Filename:= _
"D:\ExcelMacro4ErrorChart\ExamAll01Times.xlsx", FileFormat_
:=xlOpenXMLWorkbook, CreateBackup:=False
Active Window. Close
Workbooks.OpenTextFilename:= _
"D:\ExcelMacro4ErrorChart\driveD\ExamAll02Times.txt", Origin:=932 _
, StartRow:=1, DataType:=xlDelimited, TextQualifier:=xlDoubleQuote, _
ConsecutiveDelimiter:=False, Tab:=False, Semicolon:=False, Comma:=True _
, Space:=False, Other:=False, FieldInfo:=Array(Array(1, 2), Array(2, 1), _
Array(3, 1)), TrailingMinusNumbers:=True
Columns("A:C").Select
Selection. Copy
Windows("Reproducibility test 8 times.xlsm").Activate
Range("D1").Select
ActiveSheet.Paste
Windows("ExamAll02Times.txt").Activate
Application. CutCopyMode = False
ActiveWorkbook.SaveAs Filename:= _
"D:\ExcelMacro4ErrorChart\ExamAll02Times.xlsx", FileFormat_
:=xlOpenXMLWorkbook, CreateBackup:=False
Active Window. Close
Range("G1").Select
Workbooks.OpenTextFilename:= _
"D:\ExcelMacro4ErrorChart\driveD\ExamAll03Times.txt", Origin:=932 _
, StartRow:=1, DataType:=xlDelimited, TextQualifier:=xlDoubleQuote, _
ConsecutiveDelimiter:=False, Tab:=False, Semicolon:=False, Comma:=True _
, Space:=False, Other:=False, FieldInfo:=Array(Array(1, 2), Array(2, 1), _
Array(3, 1)), TrailingMinusNumbers:=True
Columns("A:C").Select
Selection. Copy
Windows("Reproducibility test 8 times.xlsm").Activate
ActiveSheet.Paste
Windows("ExamAll03Times.txt").Activate
Application. CutCopyMode = False
ActiveWorkbook.SaveAs Filename:= _
"D:\ExcelMacro4ErrorChart\ExamAll03Times.xlsx", FileFormat_
:=xlOpenXMLWorkbook, CreateBackup:=False
Active Window. Close
Workbooks.OpenTextFilename:= _
"D:\ExcelMacro4ErrorChart\driveD\ExamAll04Times.txt", Origin:=932 _
, StartRow:=1, DataType:=xlDelimited, TextQualifier:=xlDoubleQuote, _
ConsecutiveDelimiter:=False, Tab:=False, Semicolon:=False, Comma:=True _
, Space:=False, Other:=False, FieldInfo:=Array(Array(1, 2), Array(2, 1), _
Array(3, 1)), TrailingMinusNumbers:=True
Columns("A:C").Select
Selection. Copy
Application.Left = 18.625
Application.Top = 38.125
Windows("Reproducibility test 8 times.xlsm").Activate
Range("J1").Select
ActiveSheet.Paste
Windows("ExamAll04Times.txt").Activate
Application. CutCopyMode = False
ActiveWorkbook.SaveAs Filename:= _
"D:\ExcelMacro4ErrorChart\ExamAll04Times.xlsx", FileFormat_
:=xlOpenXMLWorkbook, CreateBackup:=False
Active Window. Close
Range("M1").Select
Workbooks.OpenTextFilename:= _
"D:\ExcelMacro4ErrorChart\driveD\ExamAll05Times.txt", Origin:=932 _
, StartRow:=1, DataType:=xlDelimited, TextQualifier:=xlDoubleQuote, _
ConsecutiveDelimiter:=False, Tab:=False, Semicolon:=False, Comma:=True _
, Space:=False, Other:=False, FieldInfo:=Array(Array(1, 2), Array(2, 1), _
Array(3, 1)), TrailingMinusNumbers:=True
Columns("A:C").Select
Selection. Copy
Windows("Reproducibility test 8 times.xlsm").Activate
ActiveSheet.Paste
Windows("ExamAll05Times.txt").Activate
Application. CutCopyMode = False
ActiveWorkbook.SaveAs Filename:= _
"D:\ExcelMacro4ErrorChart\ExamAll05Times.xlsx", FileFormat_
:=xlOpenXMLWorkbook, CreateBackup:=False
Active Window. Close
Range("P1").Select
Workbooks.OpenTextFilename:= _
"D:\ExcelMacro4ErrorChart\driveD\ExamAll06Times.txt", Origin:=932 _
, StartRow:=1, DataType:=xlDelimited, TextQualifier:=xlDoubleQuote, _
ConsecutiveDelimiter:=False, Tab:=False, Semicolon:=False, Comma:=True _
, Space:=False, Other:=False, FieldInfo:=Array(Array(1, 2), Array(2, 1), _
Array(3, 1)), TrailingMinusNumbers:=True
Columns("A:C").Select
Selection. Copy
Windows("Reproducibility test 8 times.xlsm").Activate
ActiveSheet.Paste
ActiveWindow.SmallScrollToRight:=2
Windows("ExamAll06Times.txt").Activate
Application. CutCopyMode = False
ActiveWorkbook.SaveAs Filename:= _
"D:\ExcelMacro4ErrorChart\ExamAll06Times.xlsx", FileFormat_
:=xlOpenXMLWorkbook, CreateBackup:=False
Active Window. Close
Range("S1").Select
Workbooks.OpenTextFilename:= _
"D:\ExcelMacro4ErrorChart\driveD\ExamAll07Times.txt", Origin:=932 _
, StartRow:=1, DataType:=xlDelimited, TextQualifier:=xlDoubleQuote, _
ConsecutiveDelimiter:=False, Tab:=False, Semicolon:=False, Comma:=True _
, Space:=False, Other:=False, FieldInfo:=Array(Array(1, 2), Array(2, 1), _
Array(3, 1)), TrailingMinusNumbers:=True
Columns("A:C").Select
Selection. Copy
Windows("Reproducibility test 8 times.xlsm").Activate
ActiveSheet.Paste
ActiveWindow.ScrollColumn = 4
Windows("ExamAll07Times.txt").Activate
Application. CutCopyMode = False
ActiveWorkbook.SaveAs Filename:= _
"D:\ExcelMacro4ErrorChart\ExamAll07Times.xlsx", FileFormat_
:=xlOpenXMLWorkbook, CreateBackup:=False
Active Window. Close
Range("V1").Select
Workbooks.OpenTextFilename:= _
"D:\ExcelMacro4ErrorChart\driveD\ExamAll08Times.txt", Origin:=932 _
, StartRow:=1, DataType:=xlDelimited, TextQualifier:=xlDoubleQuote, _
ConsecutiveDelimiter:=False, Tab:=False, Semicolon:=False, Comma:=True _
, Space:=False, Other:=False, FieldInfo:=Array(Array(1, 2), Array(2, 1), _
Array(3, 1)), TrailingMinusNumbers:=True
Columns("A:C").Select
Selection. Copy
Windows("Reproducibility test 8 times.xlsm").Activate
ActiveSheet.Paste
Windows("ExamAll08Times.txt").Activate
Application. CutCopyMode = False
ActiveWorkbook.SaveAs Filename:= _
"D:\ExcelMacro4ErrorChart\ExamAll08Times.xlsx", FileFormat_
:=xlOpenXMLWorkbook, CreateBackup:=False
Active Window. Close
Sheets("Sheet3").Select
Sheets("Sheet3").Copy Before:=Sheets(1)
ActiveWindow.ScrollColumn = 12
ActiveWindow.ScrollColumn = 1
Range("A1").Select
Sheets("Sheet3 (2)").Select
Sheets("Sheet3 (2)").Copy Before:=Sheets(1)
Columns("A:A").Select
Selection. Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
Range("A1").Select
ActiveCell.FormulaR1C1 = "PBA⇒GB1"
Range("A2").Select
ActiveCell.FormulaR1C1 = "=DECIMAL(RC[1],16)"
Selection. Copy
Range("A3").Select
Selection.SpecialCells(xlCellTypeLastCell).Select
Range("A3:A17934").Select
Range("A17934").Activate
ActiveSheet.Paste
ActiveWindow.ScrollRow = 3810
ActiveWindow.ScrollRow = 1
Range("A1").Select
Application. CutCopyMode = False
ActiveCell.FormulaR1C1 = "PBA⇒decimal"
Columns("A:A").Select
Selection. Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
Range("A1").Select
ActiveCell.FormulaR1C1 = "offset"
Range("A2").Select
ActiveCell.FormulaR1C1 = "=RC[1]-196608"
Range("A2").Select
Selection. Copy
Selection.SpecialCells(xlCellTypeLastCell).Select
Range("A3:A17934").Select
Range("A17934").Activate
ActiveSheet.Paste
ActiveWindow.ScrollRow = 3805
ActiveWindow.ScrollRow = 1
Columns("A:A").Select
Application. CutCopyMode = False
Selection. Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
Range("A1").Select
ActiveCell.FormulaR1C1 = "×2048"
Range("A2").Select
ActiveCell.FormulaR1C1 = "=RC[1]*2048"
Range("A2").Select
Selection. Copy
Selection.SpecialCells(xlCellTypeLastCell).Select
Range("A3:A17934").Select
Range("A17934").Activate
ActiveSheet.Paste
ActiveWindow.ScrollRow = 3810
ActiveWindow.ScrollRow = 1
Columns("A:A").Select
Application. CutCopyMode = False
Selection. Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
Range("A1").Select
ActiveCell.FormulaR1C1 = ""
Range("A2").Select
ActiveCell.FormulaR1C1 = "=RC[1]/1000000000"
Range("A2").Select
Selection. Copy
Selection.SpecialCells(xlCellTypeLastCell).Select
Range("A3:A17934").Select
Range("A17934").Activate
ActiveSheet.Paste
ActiveWindow.ScrollRow = 3810
ActiveWindow.ScrollRow = 1
Columns("A:A").Select
Application. CutCopyMode = False
Selection. Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
Columns("A:A").Select
Selection.NumberFormatLocal = "0.00_"
Columns("B:B").Select
Selection. Copy
Range("A1").Select
Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks_
:=False, Transpose :=False
Sheets("Sheet3 (3)").Select
Application. CutCopyMode = False
Sheets("Sheet3 (3)").Copy Before:=Sheets(1)
Columns("B:F").Select
Selection. Delete Shift:=xlToLeft
Range("B1").Select
ActiveCell.FormulaR1C1 = "PI-SUM8(1)"
Columns("C:D").Select
Selection. Delete Shift:=xlToLeft
Range("C1").Select
ActiveCell.FormulaR1C1 = "PI-SUM8(2)"
Columns("D:E").Select
Selection. Delete Shift:=xlToLeft
Range("D1").Select
ActiveCell.FormulaR1C1 = "PI-SUM8(3)"
Columns("E:F").Select
Selection. Delete Shift:=xlToLeft
Range("E1").Select
ActiveCell.FormulaR1C1 = "PI-SUM8(4)"
Columns("F:G").Select
Selection. Delete Shift:=xlToLeft
Range("F1").Select
ActiveCell.FormulaR1C1 = "PI-SUM8(5)"
Columns("G:H").Select
Selection. Delete Shift:=xlToLeft
Range("G1").Select
ActiveCell.FormulaR1C1 = "PI-SUM8(6)"
Columns("H:H").Select
Selection.ColumnWidth = 9.75
Selection.ColumnWidth = 9.81
Columns("H:I").Select
Selection. Delete Shift:=xlToLeft
Range("H1").Select
ActiveCell.FormulaR1C1 = "PI-SUM8(7)"
Columns("I:J").Select
Selection. Delete Shift:=xlToLeft
Range("I1").Select
ActiveCell.FormulaR1C1 = "PI-SUM8(8)"
Columns("J:J").Select
Selection. Delete Shift:=xlToLeft
Range("A1").Select
Sheets("Sheet3 (4)").Select
Sheets("Sheet3 (4)").Name = "PI・SUM8(1)-(8) whole area"



ActiveSheet.Shapes.AddChart xlLine, 180, 100, 800, 400

With ActiveSheet.ChartObjects(1).Chart
.SetSourceData Source:=Range(Range("A1"), ActiveCell.SpecialCells(Type:=xlCellTypeLastCell))


.SeriesCollection(1).Format.Fill.ForeColor_
.ObjectThemeColor = msoThemeColorAccent6


.Axes(xlValue, xlPrimary).HasTitle = True
.Axes(xlValue, xlPrimary).AxisTitle.Text = "Number of Errors"
.Axes(xlValue, xlPrimary).AxisTitle.Orientation = xlVertical
.Axes(xlValue, xlPrimary).TickLabels.NumberFormat = "####"

.HasTitle = True
.ChartTitle.Text = "Full Range Inspection PI-SUM8"


.HasLegend = True
.Legend.Position = xlLegendPositionTop

End With







Sheets("Sheet3 (3)").Select
Sheets("Sheet3 (3)").Copy Before:=Sheets(1)
Columns("B:G").Select
Selection. Delete Shift:=xlToLeft
Range("B1").Select
ActiveCell.FormulaR1C1 = "POF(1)"
Columns("C:D").Select
Selection. Delete Shift:=xlToLeft
Range("C1").Select
Selection. Clear Contents
ActiveCell.FormulaR1C1 = "POF(2)"
Columns("D:E").Select
Selection. Delete Shift:=xlToLeft
Range("D1").Select
ActiveCell.FormulaR1C1 = "POF(3)"
Columns("E:F").Select
Selection. Delete Shift:=xlToLeft
Range("E1").Select
ActiveCell.FormulaR1C1 = "POF(4)"
Columns("F:G").Select
Selection. Delete Shift:=xlToLeft
Range("F1").Select
ActiveCell.FormulaR1C1 = "POF(5)"
Columns("G:H").Select
Selection. Delete Shift:=xlToLeft
Range("G1").Select
ActiveCell.FormulaR1C1 = "POF(6)"
Columns("H:I").Select
Selection. Delete Shift:=xlToLeft
Range("H1").Select
ActiveCell.FormulaR1C1 = "POF(7)"
Columns("I:J").Select
Selection. Delete Shift:=xlToLeft
Range("I1").Select
ActiveCell.FormulaR1C1 = "POF(8)"
Range("A1").Select
Sheets("Sheet3 (4)").Select
Sheets("Sheet3 (4)").Name = "POF(1)-(8) whole area"
Range("A1").Select
ActiveWorkbook. Save


ActiveSheet.Shapes.AddChart xlLine, 180, 100, 800, 400

With ActiveSheet.ChartObjects(1).Chart
.SetSourceData Source:=Range(Range("A1"), ActiveCell.SpecialCells(Type:=xlCellTypeLastCell))


.SeriesCollection(1).Format.Fill.ForeColor_
.ObjectThemeColor = msoThemeColorAccent6


.Axes(xlValue, xlPrimary).HasTitle = True
.Axes(xlValue, xlPrimary).AxisTitle.Text = "Number of Errors"
.Axes(xlValue, xlPrimary).AxisTitle.Orientation = xlVertical
.Axes(xlValue, xlPrimary).TickLabels.NumberFormat = "####"


.HasTitle = True
.ChartTitle.Text = "Global Inspection POF"


.HasLegend = True
.Legend.Position = xlLegendPositionTop

End With



Sheets("POF(1)-(8) whole area").Select
Dim myChartObjPOF As ChartObject
For Each myChartObjPOF In ActiveSheet.ChartObjects
With myChartObjPOF.Chart
.Export ThisWorkbook.Path &"＼"& .ChartTitle.Text &".png"
End With
Next



Sheets("PI・SUM8(1)-(8) whole area").Select
Dim myChartObj As ChartObject
For Each myChartObj In ActiveSheet.ChartObjects
With myChartObj.Chart
.Export ThisWorkbook.Path &"＼"& .ChartTitle.Text &".png"
End With
Next





End Sub

As for the one-time recording type optical disc, the following effect can be expected to contribute to factual inference in appraisal work.
(1) Even if it is claimed that the file that should have been recorded has disappeared, digital forensics cannot find the evidence and the deleted data cannot be restored. If a pattern chart is created and it is recognized that the current readable file capacity and error patterns match, it is presumed that there is no evidence that the recorded file has been deleted.
(2) If the observed error pattern does not match the current amount of readable files, the possibility of file deletion may be inferred. For example, it is the case of FIG. 4 mentioned above.
(3) As an application, for example, in the case of Fig. 4, the person who recorded and deleted the files deletes the files (1), (2), (3), and (4) after recording, and then deletes the fifth and subsequent files. If you state that you have not recorded it, you can support it with an error pattern chart.
(4) If an uncorrectable error, such as an extremely large error pattern, has occurred in the final recorded portion of the last session, it can be assumed that the session ended abnormally due to an accident such as forced interruption of writing. Sometimes.
(5) An error pattern chart such as the example given up to the previous section can be obtained from the originals recorded in separate sessions. On the other hand, with regard to copies, regardless of whether they are copies using a personal computer or a duplicator, if the starting point to the end point are recorded at once, the appearance of the error pattern for each session will differ from that of the original. Therefore, the original and the copy can sometimes be distinguished from each other by the error pattern.
(6) After creating the original in the write-once format and turning it into evidence, if you tamper with it by adding a new file using another computer, etc., the error pattern chart shows that the error pattern in the tampered part is It can be used to detect and prove tampering, as there are steps and large error patterns appear at seams.
(7) If a very large spike-like error is observed in the error pattern chart, write session will be terminated (including abnormal termination) at that location, or temporary write will be performed to prevent buffer underrun. It may be used to discover and prove that there is a possibility that an interruption occurred and new writing was performed.
(8) If the error pattern chart has a staircase shape corresponding to the total size of the session assumed from the file size that can be read from the disc, it will be different for each session if it is a single-layer DVD/BD. It may be used to discover and prove the possibility of being recorded using a drive. However, as exceptions for multi-layer DVDs and multi-layer Blu-rays, regarding error pattern charts for 2-layer DVD-R-DL 8.5 GB and BD-R-DL 50 GB, 3-layer BD-R-XL 100 GB, and 4-layer BD-R-XL 128 GB , the error pattern chart has a staircase shape at the change of layers. On the other hand, this may be utilized for discovering and proving that recording may have been performed using a different drive for each session if the step position does not hit the seam of the layers.
(9) It is possible to create an electronic watermark that performs individual identification by utilizing the nature of errors that occur due to out-of-synchronization.
(10) It is possible to create optical discs that can be individually identified by utilizing the nature of errors caused by out-of-synchronization.
(11) Disks with the same hash value can be identified by error prints.
(12) When data on a video recording disk is damaged and cannot be restored, and analysis with conventional digital forensic tools cannot be expected, the analysis method using the error pattern chart will show error traces up to what percentage of the entire area. By making it clear what percentage of the maximum recording capacity was recorded, it can be verified in a lawsuit or the like, and can be used as evidence.

001 Drive for error counting 002 Personal computer in which application program for creating error pattern chart is installed

Claims (4)

A method for appraisal and verification of an optical disk in which data reading failure has occurred on the whole disk or a part of the disk,
a step of tracing the entire area from the inner periphery of the optical disk, which has a problem in reading data, using an optical disk inspection device, and measuring the number of errors for each sector address;
A step of creating an error pattern chart showing the number of errors in time series from the number of errors measured in the step of measuring the number of errors, wherein the error pattern chart includes addresses from the inner peripheral address to the outer peripheral address of the user area. a step of indicating the number of errors in time series for each amount of recorded data;
showing a readable chronological record of data recorded on an optical disc that is failing to read said data;
By collating the error pattern chart of the optical disc, which is the time-series error measurement value, with the time-series recorded data, the user data area of the optical disc, which has a problem in reading the data, from the start point to the end point a step of estimating the presence or absence of a data recording session and the session recording amount or recording time in a section in which data reading failure has occurred among the sections;
Appraisal/verification method for optical disc including An application program for creating an error pattern chart of an optical disc used in a tool device used for appraisal and verification of an optical disc that has a data reading failure on the whole or a part of the disc,
in said instrument device,
obtaining data obtained by measuring the number of errors for each sector address by tracing the entire area from the inner periphery of the optical disk, which has a problem in reading data, using an optical disk inspection device;
A step of creating an error pattern chart indicating the number of errors in chronological order from the number of errors obtained in the step of obtaining the measured data, wherein the error pattern chart is generated from the inner circumference address to the outer circumference address of the user area. indicating the number of errors in time series for each address or for each amount of recorded data;
obtaining readable time-series recorded data recorded on the optical disc from which reading of the data is impaired;
By collating the error pattern chart of the optical disc, which is the time-series error measurement value, with the time-series recorded data, the user data area of the optical disc, which has a problem in reading the data, from the start point to the end point a step of showing the presence/absence of a data recording session and the recording amount or recording time of the session in a section in which data reading failure has occurred among the sections so that the recording amount or recording time can be estimated;
and
The error pattern chart is capable of displaying a plurality of measurement results for multiple measurements and multiple discs for confirmation of reproducibility, overlaid as necessary.
An application program for creating optical disk error pattern charts. A method for individual identification of a copied optical disc, comprising:
a step of tracing the entire area from the inner circumference of the optical disc to be analyzed by an optical disc inspection device and measuring the number of errors for each sector address;
A step of creating an error pattern chart showing the number of errors in time series from the number of errors measured in the step of measuring the number of errors, wherein the error pattern chart includes addresses from the inner peripheral address to the outer peripheral address of the user area. By determining whether or not there is an electronic watermark recorded with an error pattern in the process and error pattern chart showing the number of errors for each amount of recorded data, it is possible to identify whether the disc is an original disc or a copied disc. wherein the original disc has the electronic watermark recorded by the error pattern, and the copied disc does not have the electronic watermark recorded by the error pattern. ,
The electronic watermark recorded by the error pattern is, in the recording of the original disc,
By repeatedly recording a small file and ending the session,
Alternatively, by repeatedly changing the recording drive as necessary, recording a small file, and ending the session,
A large spike-like out-of-synchronization error was intentionally generated on the error pattern chart.
A method for individual identification of copied optical discs. An optical disc in which an electronic watermark recorded by an error pattern is recorded in one of the user areas of the optical disc,
The digital watermark recorded by the error pattern is stored in any of the user areas of the optical disc,
By repeatedly recording a small file and ending the session,
Alternatively, by repeatedly changing the recording drive as necessary, recording a small file, and ending the session,
A plurality of large spike-like error patterns are artificially generated and recorded as an identification code,
The digital watermark by the error pattern has a property that it is not copied when the disc is copied,
The artificial large spike-like error pattern is obtained by tracing the entire area from the inner circumference of the optical disk with an optical disk inspection device, measuring the number of errors for each sector address, and measuring the number of errors in time series. When creating an error pattern chart showing the number of errors in
optical disk.

Images