JPH0831248B2 - Method and device for protecting digital data - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a digital data processing method having an error correction function, and particularly to data suitable for data protection when reproducing data from a recording medium. The present invention relates to a protection method and a protection device.

[Outline of Invention]

At the time of processing digital data, this data is divided into a predetermined length, and each divided data is used for error correction.
For example, a method is known in which a parity code or the like is added and error correction is performed for each of these divided data.

By the way, in such a method, for the purpose of identifying the above-mentioned division position, dedicated data such as a sync code is inserted.

Therefore, in the present invention, the sync code is provided with a secret code function so that data protection can be easily obtained.

[Conventional technology]

In general, during processing such as recording / reproducing of digital data, a continuous or single bit error may occur due to defects in the recording medium used, noise during reading of the recorded data, etc. An error correction method is generally applied.

By the way, as an error correction method in such a case, conventionally, a method in which a series of digital data is sequentially divided into a predetermined length and an error correction code such as a parity code is added to each of the divided data is generally used. This error correction method used in the present invention will be described with reference to FIG. 2. First, in the recording system, the input data 1 is supplied to the error correction code adding section 2, and the input data 1 is sequentially input. The data is divided into words to form an error correction block, and an error correction code is added to each error correction block to form a data structure as shown in FIG.

However, since the error correction code added at this time changes according to the content of the data, the data delimiter cannot be discriminated as it is, and such data is directly recorded on the recording medium 9 as the recording data 8 in FIG. Therefore, in the reproducing system, the input data and the error correction code cannot be distinguished from each other, and even if the error correction cannot be performed, the substance of the input data becomes unclear as it is.

Therefore, as shown in FIG. 3 (b), a code that is always constant and does not change is inserted in the leading delimiter portion of each error correction block, and the error correction code and the subsequent input are detected by detecting this code. A method for distinguishing from data is applied, and this method will be further described with reference to FIG. 2. First, in the recording system, a predetermined space is provided at the starting point of each error correction block in advance. Then, every time this space appears, the switch 6 in the code adding section 7 is switched to the code signal input 5,
As a result, a predetermined code from the code generator 4 is inserted, and as a result, the recording data 8 on the recording medium 9 becomes the data shown in FIG. 3 (b).

On the other hand, in the reproducing system, as shown in FIG.
The code detector 12 compares the data 10 read from the code generator 10 with a predetermined code (same as the code from the code generator 4) read from the code generator 11, and the start point of each error correction block is detected by detecting the coincidence. Recognize and match information 14
Generate. Then, the error correction unit 13 uses the matching information 14
Based on the above, the read data 10 is distinguished into the input data and the error correction code such as the parity code, and the error correction is performed by this to obtain the output data 15 which faithfully reproduces the input data 1.

The code used for distinction described above is generally called a sync code (also called an index or index marker).

By the way, in such a conventional digital data processing method, no particular consideration is given to data protection.

[Problems to be solved by the invention]

In recent years, digitalization of audio and video has progressed, and along with this, digital data recording / reproducing systems (digital VTR, digital audio recorder, digital audio disk, data recorder, etc.) have become popular.

Therefore, even if a recorded medium (video tape, audio tape, diskette, etc.) is available, anyone can easily obtain the recorded data, and unlike video and audio, unlike analog signals. Since the deterioration of video and audio during dubbing is eliminated, it is possible to duplicate as much as the source data.

While this is a merit, it also brings about an environment where problems such as copyright infringement are likely to occur. In particular,
In the future, it is expected that private data, such as patient examination data, personal address and telephone number registration data, and strategic data in companies, will be handled by the digital recording / playback system in many cases. Solving the above problems becomes important.

The present invention has been made in view of the above circumstances, and an object thereof is to protect digital data in a data processing system that employs an error correction method. A protection method and a protection device are provided.

[Means for solving problems]

In order to achieve the above object, the present invention uses identification data for setting a predetermined time so that the generation of a sync code used in an error correction method in a reproducing system is not output except at the time set by the identification code. It is the one.

[Action]

In the error correction method described above, the use of the sync code in the reproduction system is indispensable. If the sync code in the data cannot be detected by this, the data and the error correction code cannot be distinguished and the reproduction of the data cannot be performed. It is possible.

Therefore, in the playback system, if this sync code is generated only by the identification code set at a predetermined time, it is possible to protect the data based on time, and according to the fee paid in advance. , It is possible to allow the use of data for a predetermined fixed time.

〔Example〕

Hereinafter, a digital data protection method and a protection device according to the present invention will be described in detail with reference to illustrated embodiments.

FIG. 1 is an example of a system including a recording system and a reproducing system to which an embodiment of the present invention is applied. In the figure, 16 is a sync code in the reproducing system (hereinafter simply referred to as sync), 20,
Reference numeral 21 is a digital switch, and other components are the same as those of the conventional example shown in FIG.

Therefore, as is clear from the comparison between FIGS. 1 and 2, the difference between this system and the conventional example of FIG. 2 is that the sync 5 in the recording system and the sync 16 in the reproducing system are In the example, the codes are generated by the code generators 4 and 11 in the fixed part, respectively, and the codes are of a general type consisting of standard combinations. The sinks 5 and 16 are generated from the digital switches 20 and 21, respectively, and as a result, in this system, these sinks 5 and 16 are codes that can be arbitrarily set by the parties. is there.

 Next, the operation of this system will be described.

First, the digital switch 20 is operated so that the sink 5 composed of a code known only to the parties concerned is output from the digital switch 20. Then, in this state, the input data 1 is supplied to the error correction code adding section 2 of the recording system, and the sync 5 from the digital switch 20 is used to create the record data 8 as shown in FIG. The data 8 is recorded on the recording medium 9.

Therefore, it is assumed that a person other than the party concerned inputs the data recorded on the recording medium 9 into the reproducing system shown in FIG. 2, for example.

Then, at this time, the sync included in the data 10 read from the recording medium 9 in this reproducing system is a special switch arbitrarily set by the parties using the digital switch 20 (FIG. 1). The code detection section 12 is provided with a standard code type sync that is generally used from the code generation section 11, and therefore, As a matter of course, code detection is performed by this standard sync, and as a result, no coincidence information 14 is detected from the code detection unit 12, and the error correction unit 13 does not reproduce the data. It will be made impossible and the data will be protected.

However, as a matter of course, between the parties, the combination of the codes set by the digital switch 20 has been understood in advance, and therefore the digital switch 21 in the reproducing system has the digital switch 20 in the recording system. It is possible to set a sync consisting of the same code as the sync that was set in, and as a result, the code detection unit 12 of the reproduction system reliably detects the match information 14 at each start point of each error correction block of the read data 10. The error correction unit 13
It is possible to reliably extract the correct output data 15 from which the error has been corrected.

In such a system, a default value is generally set as a sink used therein because of its versatility.

Therefore, in this system, this default value is normally set as a sink unless special protection is required for private data etc., and digital switches 20 and 21 are used to set special values only when necessary. Just set a sync.

In addition, since 2 to 3 bytes of data are usually used as this sync, the kind of this sync can be 2 ¹⁶ to 2 ²⁴ patterns even if it is simply calculated. It is virtually impossible for anyone other than the parties concerned to create the same sync as at the time of recording by devising other than the digital switch as the sync generation unit consisting of these digital switches 20 and 21. Therefore, this system can protect data almost completely.

Here, the block diagram of the present invention is as shown in FIG. Here, FIG. 10A corresponds to the embodiment of FIG. 1, and the sync generation section here corresponds to the digital switches 20 and 21.

The sync generator is provided separately for the recording system and the reproducing system in FIG. 4 (a), but for example, the recording system such as a digital VTR, a digital data record, or a digital audio tape recorder is used. When the reproducing system and the reproducing system are provided in the same system, they may be combined in a common sync generating section as shown in FIG.

By the way, in the above system, the digital switch is used as the external digital data input means to be the sync generator. Therefore, the block diagram at this time is shown in FIG.
It becomes like the figure.

Therefore, the present invention can be implemented not only in such a system, and therefore such a system will be described below.

First, in FIG. 6A, a magnetic card reader 26 is used as an external digital data input means which serves as a sync generator. With this, data recorded on a predetermined magnetic recording card 25 is read, and a sync 27 (sync 5 or 16) is set as an example of the system, and the bar code 28 in FIG.
It is a system that reads in 29 and sets the sync (sync 5 or 16).

As described above, in the case of handling a plurality of syncs each having a code different from the default value, the system using a digital switch must store each of these syncs. Management of magnetic cards and barcodes is all that is required, which makes handling and operation easier.

By the way, in the above system, the sink may be set directly by executing some calculation.

FIG. 7 shows a system according to the present invention having such a configuration, in which a sync generation unit is configured by using a calculation unit 32, and predetermined data, for example, personal identification number data 31 is input to the sync generation unit and the calculation result is obtained. Is a sink 33 (sink 5 or 16).

FIG. 8 shows an example of the contents of calculation by the calculation unit 32. Here, as output, a person who records / reproduces with Sync-A- other than the default value, a person who records / reproduces with Sync-B-, a person who records / reproduces with Sync-C-, The recorded data can be protected by classifying the system users into, etc., and assigning the identification numbers to each. In this embodiment, it goes without saying that the classification structure and the number of classifications can be freely determined by changing the calculation contents of the calculation unit 32 shown in FIG.

Next, FIG. 9 shows another example of a system to which an embodiment of the present invention is applied. This system is a personal identification number.
34 and the identification number 35 of the recorded data (classified as any of -a- to -c- depending on which kind of sink other than the default value to use -A- to -C- is used for the recorded data. The calculation unit 36 for inputting the (number) is provided, and the calculation result of this calculation unit 36 is used as the sink 37.

FIG. 10 shows an example of calculation contents of the calculation unit 36.
In this figure, the relationship between the identification number of the recorded data and its sync is as follows.

-A-.fwdarw.-A-, -b-.fwdarw.-B-, -c-.fwdarw.-C- Incidentally, in FIG.

As a result, the individual identification numbers are the data identification numbers -a- and -c- of the recorded data, and the individual identification numbers are
The recorded data identification numbers -b- and -c- are used, and the individual identification number is the recorded data identification number -a.
The data of − and −b− can be reproduced respectively.

Therefore, according to this system, the data to be protected can be protected by classifying it into reproducible data for each user. Even in this case, the classification configuration and the number thereof can be freely determined by changing the calculation content of the calculation unit 36 in FIG.

In the system of FIG. 9, the individual identification code may be arbitrarily set according to the use such as sex, age, company, and the like.

Next, an embodiment of the present invention will be described with reference to FIG.

In this embodiment, the reproduction timer 38 and the calculation unit 40 are used as the sync generation unit in the reproduction system in the above system, and the time data output from the reproduction timer 38 is input to the calculation unit 40 as the identification code 39 to calculate the calculation result. Sink 41 (sink 16)
And

The calculation contents by the calculation unit 40 at this time are as follows.

Reproduction time ≦ T → Sink occurrence Reproduction time> T → Sink destruction That is, according to this embodiment, when the reproduction time is within a predetermined time T, the sync indicating the reproducible is the arithmetic unit 40.
When the playback time exceeds a predetermined time T, the sync is destroyed and the data cannot be played back. Therefore, it is possible to protect the data based on time and pay the fee. Can be used as a service system that permits the use of data for a predetermined fixed time.

Further, in addition to the above description, according to the present invention,
It is possible to easily protect the data based on various standards by changing the calculation contents.

The arithmetic unit in the above embodiments may be realized by hardware of a logic circuit or software of a CPU and a memory. Also, ROM and RAM
Needless to say, it may be realized by a LUT (look-up table) method using such as.

〔The invention's effect〕

As described above, according to the present invention, it is possible to protect data on the basis of time without paying for additional additional data, and only by using a sync required for error correction, and paid in advance. Since the data can be allowed to be used for a predetermined fixed time depending on the charge, the data can be sufficiently protected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a system to which an embodiment of a digital data protection method and apparatus according to the present invention is applied, FIG. 2 is a block diagram showing a conventional example of a data processing system, and FIG. 3 is data. FIG. 4 is a block diagram conceptually showing an example of a system according to the present invention, FIG.
FIG. 6 is a block diagram conceptually showing another example of the system according to the present invention, FIG. 6 is an explanatory diagram showing an example of a sync generation unit in the system of the present invention, and FIG. 7 is a sync generation unit in the system of the present invention. 8 is an explanatory view showing another example of calculation, FIG. 8 is an explanatory view of calculation contents, FIG. 9 is an explanatory view showing still another example of the sync generation unit in the system of the present invention, and FIG. 10 is an explanatory view of calculation contents. FIG. 11 is an explanatory view showing an embodiment of the present invention. 1 ... Input data, 2 ... Error correction code addition section, 5 ...
Code signal input, 6 ... Switch, 7 ... Code addition section, 8 ... Recorded data, 9 ... Recording medium, 12 ... Code detection section, 13 ... Error correction section, 14 ... Match information, 15 ... … Output data, 21, 22… Digital switch.

Claims (2)

[Claims] 1. Digital data in which continuous digital data is sequentially divided into a predetermined length, an error correction code and a sync code set to a predetermined code are added, and error correction is performed for each of these divided data. In the protection method, an identification code that appears only during a predetermined period during the digital data transmission is used, and a predetermined code necessary for identifying the sync code is output only when the identification code appears. Method for protecting digital data. 2. A recording system in which continuous digital data is sequentially divided into a predetermined length and an error correction code and a sync code set to a predetermined code are added and output, and a reproduction in which an output from the recording system is input. In the digital data protection device, which is configured to perform error correction for each of the divided data by using the error correction code and the sync code in the reproduction system, the sync code used in the recording system is External digital data input means to set arbitrarily,
External digital data input means for arbitrarily setting the sync code used in the reproduction system, timer means for generating an identification code for setting a predetermined time, the sync code used in the reproduction system and the identification And a calculation means for inputting the code, the calculation means outputs the sync code used in the reproduction system within the time set by the identification code, and outputs the sync code outside the time set by the identification code. A digital data protection device, characterized in that the sync code used in the reproduction system is destroyed so as not to be output.