JPH04170763A - Digital data recording/reproducing device - Google Patents

Abstract

PURPOSE:To enable reproduction to be in disabled state and security of data to be retained positively by disabling correction when performing error correction as far as no proper keyword data is set at the time of reproduction. CONSTITUTION:Data conversion is performed to an entire coded data where error correction coding processing is performed and redundancy data is added and it is recorded on a tape. At the time of reproduction, a coded data which should have been recorded is restored by performing inverse conversion with the same keyword as a conversion keyword which is used at the time of recording. When a keyword data which is different from the keyword data which is set at the time of recording is set at the time of reproduction, original coded data cannot be retrieved when performing inverse conversion of data and it becomes quite meaningless data as an error correction symbol so that a situation, where errors occur in nearly all data, occurs when correcting errors, a read processing exceeding the limit of correction capacity is performed, no proper reproduction is made regardless of reading, and error messages are returned to an external device as disabled reproduction, thereby completing reproduction.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a security function that allows recorded digital data to be correctly reproduced only when the same verification data as a type of verification data used during recording is set. The present invention relates to a digital data recording/reproducing device having a digital data recording/reproducing device.

(Prior Art) In recent years, computers have come to handle various software and data in all fields, and how to maintain the confidentiality of the information handled has become a major problem. The same thing can be said about magnetic recording devices, such as recording data in an encrypted manner so that it is impossible to know what data is recorded, or reading data correctly unless certain procedures are performed or some type of verification data is provided. Security functions have been implemented by preventing data from being emitted.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of conventional digital data recording and reproducing apparatuses will be described below with reference to the drawings.

FIG. 3 is a block diagram showing the configuration of a conventional digital data recording/reproducing apparatus that implements a security function by encrypting and recording information data through data conversion. In the figure, 1 is a communication unit that transmits and receives information data, control data, and encryption codes to and from an external device; 2 is an input/output memory that temporarily stores information data sent from the external device via the communication unit 1; 6 is an encoding unit that performs an error correction code encoding process on data to be recorded on a recording medium; 6 is an encoding unit that modulates recording encoded data encoded by the encoding unit 4;
7 is a demodulation unit that demodulates the reproduced signal and sends out the data as reproduced encoded data; 9 is a correction unit that corrects errors in the reproduced encoded data; 10 is configured to access the input/output memory 2; 12 is a mechanism control unit that controls the operation of the mechanism of the device such as recording operation, playback operation, search operation, etc.; 13 is a tape which is a recording medium; and 14 is a memory control unit that controls data input/output. A conversion data generation unit 15 generates data obtained by shifting each bit one bit at a time using the initial value of the encryption code as converted data used for encryption. 16 is a data inverse converter that performs the inverse conversion to the data converter 15 using the converted data output from the converted data generator 14 to decode encrypted data; 17 is an encoder 4. It is a system control unit that controls the operation of the entire system, such as controlling the processing operations of the correction unit 9 and the memory control unit 10, issuing commands such as recording operations to the mechanism control unit 12, and setting encryption codes to the converted data generation unit 14. .

The recording and reproducing operations of the conventional digital data recording and reproducing apparatus configured as described above will be explained in accordance with the flow of control.

FIG. 4 is a flowchart showing the processing procedure of the system control unit 17. In step 1, the system control unit 17 receives the encryption code and control data given from the external device via the communication unit 1, and determines the recording or playback position from the control data.
, ll+. In step 2, a search operation is commanded to the mechanism control section 12, and the end of the search is waited for. When the search is completed, in step 3, it is determined from the control data whether recording or reproduction is to be performed.

If it is a record, the process proceeds to step 19, in which the encryption code received from the external device via the communication unit 1 is set in the converted data generation unit 14, and then in step 20, the code sent from the external device via the communication unit l is set. At the same time, the controller 10 instructs the memory control section 10 to sequentially import the information data to the input/output memory 2, and to transfer the retrieved data from the input/output memory to the encoding section 4. At this time, in synchronization with the data transfer, the converted data generation unit 14 uses the set encryption code itself as an initial value and sequentially generates data obtained by shifting each bit one bit at a time as converted data, and the data conversion unit 15 inputs and outputs the data. The data sequentially sent out from the memory 2 is combined with the conversion data sequentially generated by the conversion data generation unit 14.
Data is converted (encrypted) using OR logic. In the subsequent step 6, the encoder 4 is controlled to execute error correction code encoding processing, thereby adding redundant data of the error correction code to the encrypted data. When the encoding is completed, the recorded encoded data is transferred to the modulation unit 6 in step 7, and the modulation unit 6 sequentially performs conversion and records it on the tape 13.

Step 20. 6. The process in step 7 is repeated until it is confirmed in step 8 that the required recording amount has been completed, and the recording operation is completed.

Next, the playback operation will be explained. Up to step 3, the process proceeds in the same manner as the recording operation, and if it is determined in step 3 that the control data is to be reproduced, the process proceeds to step 21. In step 21, the encrypted code used for decoding during playback is set in the converted data generation unit 14, and in the subsequent step 10, the playback encoded data sequentially demodulated by the demodulation unit 7 is received by the correction unit 9, and corrected in step 11. Control unit 9 to correct errors. In this error correction process, errors that exceed the correcting ability due to physical damage to the tape or clogging of the playback head, etc.
There may be cases where correction becomes impossible. Therefore step 12
Then, it is determined whether correction has become impossible or not, and if the correction has been successfully performed, the process proceeds to step 22, where the error-corrected reproduced information data is transferred to the input/output memory 2, and at the same time,
The information data captured on the input/output memory 2 is transferred to the communication section 1.
The memory control unit 10 is instructed to send the data to an external device via the . At this time, in the same way as in the recording operation, the reproduced information data that is sequentially transferred is subjected to sequential FOR logic with the converted data output from the converted data generation section 14 to perform data inverse conversion (decoding). As a result, the encrypted and recorded information data is restored to the original data and stored in the input/output memory 2. The above-described series of operations from step IO is repeated until it is confirmed in step 14 that the required amount of data to be reproduced has been completed, and the reproduction operation is completed. If it is determined in step 12 that correction is not possible, the process proceeds to step 15 and the mechanism control unit 12 is instructed to return the playback position to the portion that has become uncorrectable. As a result, data that could not be corrected in subsequent processing is reproduced, error corrected, and data inversely converted again. This is called reread processing.

In the following step 16, the number of times this reread processing has been performed consecutively is counted, and in step 17, if the count value is less than a predetermined maximum value, the process returns to step 14 and thereafter the reread reproduction, correction, and data reverse conversion are the same as usual. It is done like this. If the count value exceeds a predetermined maximum value, it is determined that reproduction is impossible, and the reproduced information data is not returned to the external device, but an error message or the like is returned to the external device, and the processing is terminated.

Next, we will explain the data security function. The recording/reproducing operation described above is summarized as follows. During recording, converted data is generated from the encryption code received from an external device, and data is converted by performing FOR logic with the information data to be recorded.

As a result, the information data to be recorded is encrypted, encoded with an error correction code, and recorded on the tape. During playback, the encrypted code received from the external device is converted into converted data using the same procedure as during recording, and the error-corrected encrypted data and EOR logic are used to perform inverse data conversion to the original information data. Decrypt.

Here, if the encryption code set from the external device at the time of playback is different from the encryption code used at the time of recording, the converted data used for decryption will be different from the data at the time of recording, and as a result, the reproduced encrypted data cannot be decoded correctly and is converted into completely meaningless data.

Furthermore, if the data is played back using a device that does not have a security function based on encryption, the encrypted and recorded data will be played back as is. Therefore, unless the same encryption code as the one set at the time of recording is set, the recorded data cannot be read out correctly.

As described above, the security function is realized by allowing only those who know the encryption code used during recording to reproduce and retrieve the data.

(Problem to be Solved by the Invention) However, in the conventional configuration described above, the encoded information data is recorded after being subjected to error correction encoding processing, and the data after the error correction processing is decoded. (1) Even if you play it back as unencrypted without setting an encryption code for decryption, or play it back with a device that does not have a security function based on encryption, the recorded information data will not be encrypted. However, it can be taken out (played) outside.

(2) Therefore, it is possible to specify the encryption rule from the reproduced encrypted data, and there is a possibility that it will be decrypted (deciphered) by a third party.

(3) In order to prevent the code from being decrypted, it is necessary to complicate the encryption rules, resulting in a disadvantage that the device becomes complicated and large.

The purpose of the present invention is to eliminate the drawbacks of the prior art, and to provide a digital data recording/reproducing device in which information data cannot be extracted outside the device unless collation data such as an encryption code set at the time of playback matches that set at the time of recording. It is to provide.

(Means for Solving the Problems) The digital data recording and reproducing apparatus of the present invention performs error correction code encoding processing on information data to be recorded, adds the error correction code, and generates recorded encoded data. a correction encoding means; a data conversion means for converting recorded encoded data according to a first conversion rule using a conversion keyword to generate recorded data; a conversion keyword generation means for generating a keyword; a recording and reproduction means for modulating recorded data converted using the conversion keyword and recording it on a recording medium; demodulating a signal reproduced from the recording medium to obtain reproduction data; a data inverse transformation means for inversely transforming reproduced data according to a second conversion rule corresponding to an inverse transformation of the first conversion rule using a conversion keyword to generate reproduced encoded data; and an error correction processing means that performs error correction processing using an error correction code, and the data conversion means and data inverse conversion means convert or inversely transform only the redundant data of the encoded data, only the information data, or both. It is structured as follows.

(Function) With the above-described configuration, the present invention makes error correction impossible during error correction processing unless appropriate keyword data is set at the time of reproduction, thereby causing an unreproducible state.

(Embodiment) An embodiment of the digital data recording/reproducing apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a digital data recording/reproducing apparatus according to an embodiment of the present invention.

In the same figure, parts having the same configuration as those of the conventional example shown in FIG. 3 are given the same numbers, and explanations thereof will be omitted. 3 is a conversion keyword generation unit that generates a conversion keyword according to a predetermined procedure from a keyword received from an external device; and 5 is a conversion keyword generation unit that generates an error correction code from a keyword received from an external device; On the other hand, a data conversion section 8 sequentially performs FOR logic with the conversion keyword outputted by the conversion keyword generation section 3 and performs data conversion; 11 is a system control unit that controls the operation of the entire system according to control data obtained via the communication unit 1.

The operation of the digital data recording/reproducing apparatus configured as above will be explained.

First, the recording operation will be explained according to the flow of processing. FIG. 2 is a flowchart showing the processing procedure of the system control unit 11. In step 1, keyword data and control data are received via the communication unit 1, and in step 2, a recording position is searched. If the control data obtained via the communication unit 1 in step 3 is a record, the process proceeds to step 4 and converts the keyword data received from the external device into the keyword generation unit 3.
Set to . In the following step 5, the memory control unit 10 is instructed to input the information data sent from the external device into the input/output memory 2, and at the same time, sequentially transfer the acquired information data to the encoding unit 4. The encoder 4 is controlled to perform error correction code encoding processing. In step 7, the encoded recording data to which redundant data has been added by the encoding process is transferred to the modulator 6. At this time, in synchronization with the data transfer, the conversion keyword generation unit 3
The keywords set in step 4 are sequentially output as they are as conversion keywords, and the data conversion unit 5 sequentially performs FOR logic on the transferred recording encoded data and the conversion keyword output from the conversion keyword generation unit 3 to perform data conversion. As a result, the recording data in which both information data and redundant data have been converted is modulated by the modulator 6 and recorded on the tape. The processes of steps 5, 6, and 7 are repeated until the end of recording is confirmed in step 8, and the recording operation is completed.

Next, the playback operation will be explained. If it is determined in step 3 that the control data is for reproduction, the process proceeds to step 9 and sets the keyword data received together with the control data in the converted keyword generation section 3. In step 10, the reproduced data demodulated by the demodulating section 7 is sequentially taken into the correcting section 9. At this time, in synchronization with the data transfer, the conversion keyword generation unit 3
The keywords set in step 9 are sequentially output as converted keywords as they are, and the data inverse converter 8 sequentially performs EOR logic on the transferred reproduced data and the converted keyword outputted by the converted keyword generator 3 to inversely convert the data.

As a result, the data converted and recorded is restored to the original encoded data. In the following step 11, the correction unit 9 is controlled to correct the errors in the restored reproduced encoded data, and if it has not become uncorrectable in step 12, as in the conventional example, the error-corrected information data is corrected in step 13. At the same time as transferring the data to the input/output memory 2, the memory control unit 10 is instructed to transmit the transferred data to an external device via the communication unit l. The series of processing from step 1o is repeated until completion of reproduction is confirmed in step 14, and the reproduction operation is terminated. Further, when it is determined in step 12 that correction is impossible, reread processing is performed within a predetermined maximum number as in the conventional example.

Next, the security function of the present invention will be explained.

In this embodiment, as described in the explanation of the recording/reproducing operation,
The entire encoded data, which has been subjected to error correction encoding processing and redundant data has been added, is subjected to data conversion and recorded on tape. During reproduction, the encoded data that should have been recorded is restored by performing inverse transformation using the same transformation keyword as that used during recording.

In other words, if keyword data different from the keyword data set at the time of recording is set at the time of reproduction, the original encoded data will not be returned at the time of data inverse conversion. This results in completely meaningless data as an error correction code. Therefore, at the time of error correction, errors occur in most of the data, and reread processing is performed without fail beyond the limit of the correction ability. However, no matter how many times the data is reread, it cannot be played back correctly, and an error message or the like is returned to the external device indicating that playback is not possible, and the playback ends.

Furthermore, even when the data is reproduced by a device without a security function, the reproduced data is data in which even redundant data has been converted at the time of recording, so the data is meaningless as error correction code data. Therefore, even if the correction process is performed as it is, the state will be the same as that described above, and reproduction will not be possible.

As described above, according to this embodiment, unless the same keyword data as the keyword data set at the time of recording is set at the time of playback, no matter how many times the reading is done, the information cannot be corrected and the information data cannot be reproduced. is not output to an external device.

Note that the same effect can be obtained when data conversion and data inverse conversion are performed not on the entire coded data but only on the encoded information data or only on the redundant data. Further, complex encryption rules may be applied to the conversion keyword.

(Effects of the Invention) The digital data recording and reproducing apparatus of the present invention includes an error correction encoding means that performs error correction code encoding processing on information data to be recorded and generates recording encoded data, and a conversion keyword. Only redundant data of recorded encoded data,
Alternatively, a data conversion means converts information data or both according to a first conversion rule to generate recorded data, and a conversion keyword generates a converted keyword according to a predetermined procedure from keyword data given from an external device. a generating means, a recording/reproducing means for modulating the recorded data converted using the conversion keyword and recording it on a recording medium, and demodulating the signal reproduced from the recording medium to obtain reproduced data; A data inversion means for inversely transforming the reproduced data according to a second conversion rule corresponding to the inverse transformation of the first conversion rule to generate reproduced encoded data; By being equipped with an error correction processing means that performs correction processing, unless a valid keyword is set at the time of playback, the data cannot be played back and the data cannot be taken out, and the confidentiality of recorded data can be more reliably maintained. It is. Also some fixed data and EOR
It is highly practical, as it provides extremely high security effects with extremely simple operations such as taking logic and converting it.

Moreover, even if the data before correction can be retrieved, the recorded data is encrypted by data conversion and cannot be decoded immediately, so the effect is great.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a digital data recording and reproducing apparatus in an embodiment of the present invention, FIG. 2 is a flowchart of processing of a system control unit in an embodiment of the present invention, and
FIG. 4 is a block diagram showing the configuration of a conventional digital data recording/reproducing apparatus, and FIG. 4 is a flowchart of processing of a system control section in the conventional example. 1...Communication section, 2...Input/output memory, 3.
...Conversion keyword generation unit, 4...Encoding unit,
5...Data conversion section, 6...Modulation section, 7
... Demodulation section, 8 ... Data inverse conversion section, 9.
... Correction section, 10... Memory control section, 11... System control section, 12... Mechanism control section, 13...
Magnetic tape. Patent applicant Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] (1) An error correction encoding means that performs an error correction code encoding process on the information data to be recorded and adds the error correction code to generate recorded encoded data, and converts the recorded encoded data using a conversion keyword. a data converter that converts data according to a first conversion rule to generate recorded data; and a conversion keyword generator that generates a converted keyword using keyword data provided from an external device as is or from the keyword data according to a predetermined procedure. means and
a recording/reproducing means for modulating the recorded data converted using the conversion keyword and recording it on a recording medium, demodulating the signal reproduced from the recording medium to obtain reproduced data; data inverse transformation means for inversely transforming the reproduced data according to a second conversion rule corresponding to an inverse transformation of the conversion rule to generate reproduced encoded data; 1. A digital data recording/reproducing device comprising: error correction processing means for performing error correction processing. (2) The data converting means and the data inverse converting means are configured to convert only the redundant data of the encoded data or only the information data.
2. The digital data recording and reproducing apparatus according to claim 1, wherein the digital data recording and reproducing apparatus performs conversion and inverse conversion on one or both of them.