JP2009187173A - Image recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recording apparatus that can detect not only direct manipulations but also "spoofing" manipulations of image data. <P>SOLUTION: The image recording apparatus 20 includes an image data creation means 39 for creating headed image data D<SB>2</SB>from image data D<SB>1</SB>, a first hash value generation means 40 for generating a first hash value 61 from header information D<SB>HE</SB>in the image data D<SB>2</SB>, a second hash value generation means 41 for generating a second hash value 62 from the image data D<SB>1</SB>in the image data D<SB>2</SB>, a first encrypted data generation means 42 for generating encrypted data 63 from the second hash value 62 and an encryption key K, a hash value/encrypted data addition means 43 for adding the first hash value 61, second hash value 62 and first encrypted data 63 to the image data D<SB>2</SB>to create image data D<SB>3</SB>, and a recording means 44 for recording the image data D<SB>3</SB>created by the hash value/encrypted data addition means 43 in an image storage device 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image recording apparatus having a function of determining whether image data stored in an image storage apparatus has been tampered with.

  In recent years, image compression techniques such as JPEG (Joint Picture Experts Group), Motion JPEG, and JPEG2000 have been used in various fields. Such an image compression technique is, for example, in the field of a video monitoring system that captures and monitors a predetermined monitoring target, and compresses a digital image captured by an imaging camera and continuously stores it in an image storage device. Has been used to. The digital image stored by the video surveillance system may be used as evidence video when an incident occurs. Therefore, in the video surveillance system, it is indispensable to ensure the reliability (truth) of the stored digital image, and it is significant that it can be proved that the stored digital image has not been tampered with.

  On the other hand, in recent years, application software that can synthesize a digital image with another digital image, or modify / delete a part of the digital image has become widespread. Therefore, it is possible to tamper with a digital image relatively easily. Therefore, it is important to detect a falsification by detecting falsification when the stored digital image is falsified and to detect falsification by “spoofing”.

  As a technique for detecting such tampering, for example, there is Patent Document 1. In this document, at the time of recording, one field of image data is blocked so as to be n bytes long in the horizontal (horizontal) direction, and this blocked data is calculated in the vertical (vertical) direction. The n-byte data is stored as the first alteration detection data together with the image data on the recording medium, and the second detection data is obtained by performing the same calculation as the recording on the image data at the time of reproduction. An apparatus is disclosed that compares detection data with second detection data and determines whether image data has been tampered with based on the comparison result.

Japanese Patent No. 3022462 (paragraphs 0014-0019, FIG. 3)

  However, in the above-described conventional apparatus, since the process for obtaining the detection data is a relatively simple and monotonous calculation process, the contents of the calculation are easily guessed, and a person who alters the image data can detect the detection data. However, there is a possibility that the falsification may be permitted by “spoofing” that prevents falsification from being detected. For this reason, the above-described conventional apparatus has problems in that the accuracy of tamper detection is low and tampering due to “spoofing” cannot be detected.

  An object of the present invention is to solve the above-described problems, and in an image recording apparatus that records image data in an image storage apparatus, the image data is altered with respect to the recorded image data. An object of the present invention is to provide an image recording apparatus that can detect not only alteration by “spoofing”.

  In order to solve the above-mentioned problem, a first aspect of the present invention is an image recording apparatus for recording image data in a predetermined image storage device, a key memory for storing an encryption key, and a header from the image data. Header-attached image data creation means for creating attached image data, first hash value generation means for generating a first hash value from the header information for each field of the header-attached image data, and the header-attached image For each field of data, second hash value generation means for generating a second hash value by concatenating the generation of the first hash value from the image data, and for each field of the image data with header First encrypted data generation means for generating first encrypted data from the corresponding second hash value and the encryption key output from the key memory A hash value / encrypted data adding means for creating recording image data by adding the first hash value, the second hash value, and the first encrypted data to a field of their generation source, and the hash Recording means for recording the recording image data created by the value / encrypted data adding means in a predetermined image storage device, and for each field of the recording image data read from the predetermined storage device, Third hash value generating means for generating a third hash value from the header information, and a first comparison for comparing the third hash value and the first hash value added to the generation source field And a first determination unit for determining whether the header information of the field is falsified based on the comparison result of the first comparison unit, and reading from the predetermined storage device. A fourth hash value generating means for generating a fourth hash value by connecting the generated image data to each field of the recording image data and generating the third hash value from the image data; Based on the comparison result of the second comparison means for comparing the hash value of the first hash value and the second hash value added to the generation source field, and the comparison result of the second comparison means. Second determination means for determining presence / absence; second encrypted data generation means for generating second encrypted data from the fourth hash value and the encryption key output from the key memory; and A comparison between the encrypted data comparing means and the encrypted data comparing means for comparing the second encrypted data and the first encrypted data added to the generation source field of the fourth hash value used for the generation thereof Based on the result, there is provided encrypted data determination means for determining whether or not the field has been tampered with by “spoofing”.

  According to the first aspect of the present invention, the first hash value, the second hash value, and the first encrypted data are generated for each field of the image data, and they are added to the fields from which they are generated. To record in the image storage device. Then, for each field of the image data read from the image storage device, a third hash value, a fourth hash value, and a second encrypted data are generated, and for each field, the first hash value and The third hash value is compared to determine whether or not the header information has been tampered with, the second hash value and the fourth hash value are compared to determine whether or not the image data has been tampered with, and the first encryption The data and the second encrypted data are compared to determine whether or not tampering due to “spoofing” has occurred. Thereby, it is possible to detect not only alteration of image data and header information but also alteration due to “spoofing” with respect to image data recorded in the image storage device.

Embodiment 1 FIG.
<Overall configuration>
In the image recording apparatus according to this embodiment, in the image recording apparatus that records image data in the image storage apparatus, not only the image data and header information but also the falsification by “spoofing” is performed on the recorded image data. It can be detected.

  As shown in FIG. 1, the image recording apparatus 20 includes a video signal input terminal 1 connected to an imaging camera 23, an NTSC decoder 2, an image compression processing unit 3, a control processing unit 4, an image memory 5, A video signal information input terminal 6 connected to the imaging camera 23, a CPU (central processing unit) 7, a program memory 8, a working memory 9, a key memory 10, an instruction input unit 11, and an image expansion processing unit. 12, an NTSC encoder 13, a synthesis processing circuit 14, a video signal output terminal 15 connected to a monitor 22, and an image data input / output terminal 16 connected to an image storage device 21.

Here, the image recording device 20 constitutes, for example, a video monitoring system together with the image storage device 21, the monitor 22 and the imaging camera 23, and the video storage device 21 receives the video signal S _P1 and the header information D _HD from the imaging camera 23. And the video signal S _P1 is displayed on the monitor 22 in accordance with an instruction from the instruction input unit 11.

The video signal input terminal 1, S _PI (NTSC signal, for example an analog system) video signal from the imaging camera 23 is input. The video signal information input terminal 6 is input with header information D _HE relating to a header created based on imaging information obtained from the imaging camera 23.

NTSC decoder 2 converts the video signal S _PI from video signal input terminal 1 to the image data D ₀ of the digital system.

The image compression processing unit 3 compresses the image data D ₀ from the NTSC decoder 2 by a predetermined method such as JPEG2000 and outputs the compressed image data D ₁ .

The control processing unit 4 associates the image data D ₁ from the image compression processing unit 3 and the header information D _HE from the data video signal information input terminal 6 for each field to create image data D ₃ with a header. . Then, the control processing unit 4 uses the encryption key K stored in the key memory 10 from each field of the image data D ₃ to generate a hash value and encryption data for falsification detection, and generates them as a generation source. in addition to the field to create the image data for recording D _3, to rECORD (storage) of the image data D ₃ to the image storage device 21.

When the control processing unit 4 performs a falsification detection process on the image data D ₃ stored in the image recording device 21 in response to a user instruction from the instruction input unit 11 and detects falsification as a result of the detection. , the information of alteration position (e.g., header information D _HE tampering of information, and tampering of the detected field field information, such as number of by tampering or the image data D ₁ of the or alteration "spoofing") of the working memory 9 and output to the image composition circuit 14 for display on the monitor 22.

The control processing unit 4 causes the monitor 22 to display the image data D ₁ from the image compression processing unit 3 or the image data D ₃ stored in the image storage device 21 in accordance with a user instruction from the instruction input unit 11. Therefore, the data is output to the image expansion processing unit 12.

The image memory 5 temporarily stores various data such as the image data D1 from the control processing unit 4 and the header information _DHE .

  The CPU 7 operates based on a program stored in the program memory 8 and a user instruction from the instruction input unit 11, and controls the operation of the image recording apparatus 20.

  The key memory 10 is activated by the CPU 7 at the time of initialization, generates random numbers at the time of activation, generates n encryption key data (hereinafter referred to as encryption keys) K1 to Kn, and stores them. The n encryption keys K1 to Kn may be prepared in advance instead of being generated at the time of activation. Hereinafter, when the encryption keys K1 to Kn are not distinguished, they are referred to as an encryption key K.

The key memory 10, to request encryption keys from the control unit 4, one by one encryption key K in the fields of the image data D ₂ is associated, which and is set in advance for each field of the image data D ₂ In addition, the encryption key K is changed in a predetermined circulation order (for example, the circulation order of K1 → K2 → K3 →... → Kn → K1), and the n encryption keys K1 to Kn are selectively transmitted to the control processing unit 4. Output. In other words, the key memory 10 outputs the n encryption keys K1 to Kn to the control processing unit 4 so that different encryption keys K correspond to the first n fields, respectively. Are output to the control processing unit 4 such that different encryption keys K correspond to the n fields.

  The working memory 9 stores information on the tampered portion when tampering is detected as a result of tampering detection processing by the control processing unit 4.

The image expansion processing unit 12 expands the image data D ₁ from the image compression processing unit 3 output from the control processing unit 4 or the image data D ₃ from the image storage device 21 output from the control processing unit 4. The expanded image data D ₄ is output to the NTSC encoder 13.

The NTSC encoder 13 converts the image data D ₄ expanded by the image expansion processing unit 12 into an analog video signal S _PO .

The composition processing circuit 14 superimposes the information on the falsified portion from the control processing unit 4 on the analog video signal S _PO from the NTSC encoder 13 and outputs the superimposed information to the monitor 22.

  The image storage device 21 is an information storage device including an information recording medium such as a hard disk recording device, an optical disk recording device, or a magnetic tape recording device. A plurality of the image storage devices 21 may be connected to the image recording device 20 in parallel or in series. Further, the image storage device 21 may be built in the image recording device 20.

<Configuration of control processing unit 4>
As shown in FIG. 3, the control processing unit 4 functions as a functional block for recording an image in the image storage device 21, and includes image data D ₁ from the image compression processing unit 3 and header information D from the data video signal information input terminal 6. a header with image data creating means 39 which mutually associates _HE for each field to create a header with the image data D _2, the first hash value 61 from the header information D _HE for each field of the image data D ₂ First hash value generation means 40 to be generated and a first hash value 62 for each field of the image data D ₂ , which is connected to the generation of the first hash value 61 from the image data D ₁ . 2 hash value generation means 41, first encryption data generation means 42 that generates encryption data 63 from the second hash value 62 and the encryption key K from the key memory 10, and A first hash value 61, the second hash value 62 and the first hash value and the encrypted data adding means 43 the encrypted data 63 in addition to their origin field to create image data for recording D _3, And a recording unit 44 that records the image data D ₃ created by the hash value / encrypted data adding unit 43 in the image storage device 21.

The control processing unit 4, a functional block that detects tampering of the header information D _HE, image storage apparatus a third hash value 65 from the header information D _HE for each field of the image data D ₃ read from the 21 Third hash value generation means 45 for generating the first hash value 65, the first comparison means 48 for comparing the generated third hash value 65 and the first hash value 61 added to the field of the generation source, And a first determination unit 49 that determines a comparison result of the first comparison unit 48.

The control processing unit 4 also functions as a functional block for detecting falsification of the image data D ₁ for each field of the image data D ₃ read from the image storage device 21 from the image data D ₁ to the third hash value. A fourth hash value generating means 46 for generating a fourth hash value 66 in connection with the generation of 65, a generated fourth hash value 66, and a second hash value added to the generation source field 62 and a second determination means 51 for determining a comparison result of the second comparison means 50.

  In addition, the control processing unit 4 uses the fourth hash value 66 generated by the fourth hash value generation unit 46 and the encryption key K from the key memory 11 as a functional block for detecting falsification due to “spoofing”. The second encrypted data generating means 47 for generating the second encrypted data 67, the generated second encrypted data 67, and the fourth hash value 66 used in the generation of the second encrypted data 67 Encryption data comparison means 52 that compares the encrypted data 63 with one encryption data, and encryption data determination means 53 that determines the comparison result of the encryption data comparison means 52.

  The control processing unit 4 also includes a determination result output unit 54 that outputs the determination results of the first determination unit 49, the second determination unit 51, and the encrypted data determination unit 53 to the synthesis processing circuit 14 and the working memory 9. .

<Description of operation>
Next, the operation of the image recording process of the image recording apparatus 20 will be described with reference to FIG.

In step ST1, the user instruction to start image recording from the instruction input unit 11 is input, in step ST2, the image signal S _PI inputted to the video signal input terminal 1, the image data D of digital in NTSC decoder 2 is converted into _0, and then is input to the control processing unit 4 is in the image compression processing unit 3 is image compression compressed image data D ₁ in. At the same time, the header information D _HE input to the image signal information input terminal 6 is also input to the control processing unit 4.

Then at step ST3, the image data D ₁ and the header information D _HE inputted to the control unit 4, the header-added image data creation unit 39, as in FIG. 2, the image associated with each other for each field 58 It is temporarily stored in the memory 5. In this way, the header-attached image data D ₂ is created from the image data D ₁ and the header information D _HE . Then, the control processing unit 4 reads the image data D ₂ from the image memory 5 for each field 58.

Each field 58 is assigned field numbers # 1, # 2,... Uniquely determined. The header information D _HE of each field 58 includes the imaging date and time, the shooting location, the recording condition, the own field number, and the like regarding the image data D ₂ of the same field 58.

In step ST4, as in FIG. 4, with respect to field 58 of the First (ie # 1), the first hash value generation unit 40, the field 58 from the header information D _HE, the header information D _HE A first hash value 61a (61) from which features are extracted is generated. Then in step ST5, the second hash value generation unit 41, linked to the generation of the first hash value 61a (61), from the image data D ₁ of the same field 58, the characteristics of the image data D ₁ The extracted second hash value 62a (62) is generated.

  In step ST6, the first encrypted data 63 is used to generate the first hash value 62a and the first encryption key K1 selectively read from the key memory 10 in a predetermined circulation order. Encryption data 63a (63) is generated.

In step ST7, as shown in FIG. 4, the first hash value 61a, the second hash value 62a, and the first encrypted data 63a generated by the hash value / encrypted data adding means 43 are stored in the field # 1 ( That is, it is added to the field 58 of their generation source. Thus, # 1 field 58 of the recording image data D ₃ from # 1 field 58 of the image data D ₂ is generated. The created recording image data D ₃ is recorded (accumulated) in the image accumulating device 21 by the recording means 44 as shown in FIG.

And similarly, the next subsequent image data D ₂ (i.e. # 2, # 3, ...) of performs steps ST4~ST7 for all field 58, generated each field 58 the image of the image data D ₃ Record (store) in the storage device 21.

In FIG. 4, as shown in the correspondence table 10, the fields 1, # 2, # 3,... Of the image data D ₂ are associated with the encryption keys K1, K2, K3,. Yes. And, the field 58 of the # 2, and the first hash value 61b generated from the header information D _HE of the field 58, and a second hash value 62b generated from the image data D ₁ of the the field 58, The first encrypted data 63b generated from the second hash value 62b and the encryption key K2 corresponding to the field 58 is added. Similarly, the first hash value 61c,..., The second hash value 62c,..., And the first encrypted data 63c,. The fields 58 of the recording image data D ₃ created in this manner is stored in the image storage device 21 as in FIG.

  Next, the operation of the alteration detection process of the image recording apparatus 20 will be described with reference to FIG.

In step ST11, when the user instructs alteration detection starting from the instruction input unit 11 is input, in step ST12, the control processing unit 4, recording image data D ₃ stored in the image storage apparatus 21 for each field 58 Read out.

In step ST13, initially (i.e., # 1) with respect to field 58, the third hash value generation unit 45, as in FIG. 7, the header information D _HE of the field 58, the first hash value 61 The third hash value 65a (65) is generated by the same method as that described above. And the fourth hash value generation unit 46, linked to the generation of the third hash value 65a, the image data D ₁ of the same field 58, in the same way as the method of generating the second hash value 62, the 4 hash values 66a (66) are generated.

Then, in step ST14, the first comparison means 48 adds the generated third hash value 65a and the # 1 field (that is, the field from which the third hash value 65a is generated) 58. The first hash value 61a is compared. In step ST15, the first determination unit 49 determines whether or not the header information _DHE is falsified according to the comparison result.

That is, if the comparison result of the first comparison unit 48 does not match in step ST15, the process proceeds to step ST16, and the first determination unit 49 determines that the header information _DHE has been tampered with. In step ST17, the determination result (information such as the fact that the header information _DHE has been tampered and the field number where the tampering has been detected) is output from the first comparison unit 48 to the determination result output unit 54. The determination result is output from the determination result output means 54 to the synthesis processing circuit 14 and displayed on the monitor 22, and is output from the determination result output means 54 to the working memory 9 and stored. Then, the process proceeds to step ST27, where the falsification detection process in the field 58 of # 1 is terminated.

On the other hand, if the comparison result by the first comparison unit 48 matches in step ST15, the process proceeds to step ST18, and the first determination unit 49 determines that the header information _DHE has not been falsified. Then, the process proceeds to step ST19.

In step ST19, the second comparison unit 50 adds the fourth hash value 66a generated in step ST13 and the # 1 field (that is, the field from which the fourth hash value 66a is generated) 58. The second hash value 62a being compared is compared. In step ST20, the second determination unit 51, determination of the presence or absence of the falsification of the image data D ₁ is performed according to the comparison result.

That is, in step ST20, if the result of the comparison by the second comparison means 50 do not coincide, the process proceeds to step ST21, the second determination unit 51, alteration of the image data D ₁ is determined that there. The flow advances to step ST17, save in the same manner as described above, the working memory 9 together with the determination result (information such as detected field number indicating tampering of the image data D ₁ is present and its tampering) is displayed on the monitor 22 Is done. Then, the process proceeds to step ST27, where the falsification detection process in the field 58 of # 1 is terminated.

On the other hand, in step ST20, if the result of the comparison by the second comparison means 50 coincide, the process proceeds to step ST22, the second determination unit 51, alteration of the image data D ₁ is determined not. Then, the process proceeds to step ST23.

  In step ST23, the second encrypted data generation stage 47, as shown in FIG. 7, the fourth hash value 66a generated in step ST13 and the predetermined cyclic order from the key memory 10 (that is, the predetermined hash order in step ST6). From one encryption key (that is, the same encryption key used to generate the first encrypted data 63a) K selectively read out in the same circulation order as The second encrypted data 67a is generated by the same method as the method of generating the first encrypted data 63. The encrypted data comparing means 52 adds the second encrypted data 67a and the # 1 field (that is, the source field of the fourth hash value 66 used in generating the encrypted data 67a) 58. The first encrypted data 63a being compared is compared.

  Then, in step ST24, the encrypted data determination unit 53 determines whether or not falsification by “spoofing” is performed according to the comparison result.

  That is, if the comparison result by the encryption data comparison unit 52 does not match in step ST24, the process proceeds to step ST25, and the encryption data determination unit 53 determines that there has been falsification due to “spoofing”.

That is, in some fields 58, alteration of the header information D _HE and image data D ₁ is performed, further the first and second hash values 61a on the basis of the contents of the alteration, even when 62a is falsified, first If the encrypted data 63a and the second encrypted data 67a do not match, it is detected as falsification due to “spoofing”.

For example, the image data D1 in a certain field 58 and the first hash value 61, the second hash value 62, and the first encrypted data 63 added to the image data D1 are copied in the other field 58 as they are. Or, when a certain field 58 is altered in a field unit with another field 58, the first hash value 61 and the third hash value 65, and the second hash value 62 and the fourth hash value 66 Are identical to each other (thus, it is determined that the header information D _HE and the image data D ₁ are not falsified), but the first encrypted data 63 and the second encrypted data 67 correspond to the encryption key K for each field 58. This is because they do not match (hence, it is determined that there has been falsification due to “spoofing”).

  Then, the process proceeds to step ST17, and the determination result (information such as the presence of falsification due to “spoofing and the field number where the falsification has been detected) is displayed on the monitor 22 and stored in the working memory 9 as described above. Is done. Then, the process proceeds to step ST27, where the falsification detection process in the field 58 of # 1 is terminated.

  On the other hand, if the comparison results by the encrypted data comparison unit 52 match in step ST24, the process proceeds to step ST26, and the encrypted data determination unit 53 determines that there has been no falsification due to “spoofing”. Then, the process proceeds to step ST27, where the falsification detection process in the field 58 of # 1 is terminated.

And similarly, following after (i.e. # 2, # 3, ...) of the image data D ₃ to be read out from the image storage device 21 performs the processing of steps ST13~ST27 for every field 58. When the falsification detection process for all the fields 58 is completed, the falsification detection process is terminated.

In FIG. 7, step # 2 in field 58 of the image data D _3, the third hash value 65b, the encryption key that is corresponding to the fourth hash value 66b and the field 58 and its fourth hash value 66b The second encrypted data 67b generated from K2 is generated, and the first hash value 61b, the second hash value 62b, and the first encrypted data 63b added to the same field 58 with each of them are generated. Are compared. Similarly, the third hash value 65c,..., The fourth hash value 66c,... And the second encrypted data 67c,. The first hash value 61c, ..., the second hash value 62c, ... and the first encrypted data 63c, ... added to the field 58 are compared.

  In step ST23, the encryption key K used for generating the second encrypted data 67 needs to be the same as the encryption key K used for generating the first encrypted data 63 to be compared. . However, the encryption key K used in the generation of the first encrypted data 63 added to the field 58 read first is the n encryption keys K1 to Kn stored in the key memory 10. If it is not possible to identify which of these is ST30, ST24 is changed to the following steps ST23a, ST24a, respectively.

  That is, when generating the second encrypted data 67 in step ST23a, the second encrypted data generating means 47 reads all n encryption keys K1 to Kn from the key memory 10, and the first encrypted data 63 is read out. The n second encrypted data 67 for the encryption keys K1 to Kn are generated by the same method as that described above. Then, the encrypted data determination unit 53 compares each of the n second encrypted data 67 with the first encrypted data 63. If it is determined in step ST24a that there are n second encrypted data 67 that match the first encrypted data 63, the process proceeds to step ST26, where the encrypted data determination means 53 It is determined that there is no falsification due to “spoofing”. On the other hand, if it is determined in step ST24a that none of the n second encrypted data 67 matches the first encrypted data 63 as a result of the comparison in step 23a, the process proceeds to step ST25, where encrypted data determination means 53, it is determined that there has been falsification due to “spoofing”.

  As described above, in the case where there are n pieces of second encrypted data 67 that match the first encrypted data 63, the encryption used to generate the matched second encrypted data 67 is used. The key (this encryption key is called Kp) is specified as the encryption key K used in the generation of the first encryption data 63 to be compared. If this is specified, step ST23 is adopted instead of step ST23a in the subsequent field 58, and the encryption key K used for generating the second encrypted data 67 is read from the key memory 10. Reads one from the encryption key K next to the specified encryption key Kp in accordance with a predetermined circulation order. As a result, the same encryption key K used for generating the first encryption data 63 to be compared is read from the key memory 10 as the encryption key K used for generating the second encryption data 67.

  If it is determined in step ST23a that none of the n second encrypted data 67 matches the first encrypted data 63 and the encryption key Kp cannot be specified, the subsequent steps are performed. Also in the field 58, steps ST23a and ST24a are adopted, and when the encryption key Kp is specified, steps ST23 and ST24 are adopted in the subsequent field 58.

According to the image recording apparatus 4 constructed as described above, for each field 58 of the image data D _2, and generates a first hash value 61, the second hash value 62 and the first encryption data 63, They are added to the field 58 of their generation source and recorded in the image storage device 21. Then, for each field 58 of the image data D ₃ read from the image storage device 21, the third hash value 65, and generates a fourth hash value 66 and second encryption data 67, each field every 58 In addition, the first hash value 61 and the third hash value 65 are compared to determine whether or not the header information _DHE has been tampered with, and the second hash value 62 and the fourth hash value 66 are compared. It is determined whether or not the image data D ₁ has been tampered with, and the first encrypted data 63 and the second encrypted data 67 are compared to determine whether or not tampering due to “spoofing” has occurred. Thereby, it is possible to detect not only alteration of the image data D ₁ and the header information D _HE but also alteration by “spoofing” of the image data D ₃ recorded in the image storage device 21.

The key memory 10 stores the n different encryption keys K each other, one by one encryption key K into the fields 58 of the image data D ₂ is associated, and for each field 58 in a predetermined circulating order The encryption key K is changed and n encryption keys K are selectively output to the first encrypted data generation means 42. As a result, a limited number n of encryption keys K can be made to correspond to different encryption keys K to each field 58 as much as possible. That is, it is possible to effectively detect tampering due to “spoofing” with a limited number n of encryption keys K.

Further, the key memory 10 changes the encryption key K in the same predetermined circulation order as when it is output to the first encrypted data generation means 42 for each field 58, and the n number of encryption keys K are changed to the second encryption key K. The data is selectively output to the encrypted data generation means 47. Thus, if the encryption key K used in the generation of the first encrypted data 63 added to the first field 58 of the image data D ₃ read from the image storage device 21 can be specified, the image data D ₃ For each subsequent field 58, the same encryption key K used for generating the first encrypted data 63 to be compared is easily used as the encryption key K used for generating the second encrypted data 67. It can be made to correspond to.

Incidentally, if the encryption key K used in generation of the first cryptographic data 63 added to the first field 58 of the image data D ₃ read from the image storage device 21 can not be specified, as follows To do. That is, the second encryption data generation means 47 reads n encryption keys K from the key memory 10 to generate n second encryption data 67 for the n encryption keys K, and compares the encryption data The means 52 compares each of the n second encrypted data 67 with the first encrypted data 63. As a result of the comparison, if there is data that matches the first encrypted data 63 among the n second encrypted data 67, the data is output to the first encrypted data generating means 42 by the key memory 10. Generation of n encryption keys K from the encryption key K next to the encryption key K used in the generation of the matched second encryption data 67 in accordance with the same predetermined cyclic order as Selective output to means 47. Thereby, even when the encryption key K used in the generation of the first encrypted data 63 added to the first field 58 of the image data D ₃ read from the image storage device 21 cannot be specified, the image data D _For each field 58 subsequent to _3, the same encryption key K used in generating the first encrypted data 63 to be compared as the encryption key K used in generating the second encrypted data 67 Can be easily handled.

  Further, since the n encryption keys K are generated by generating random numbers at the time of activation, the n encryption keys K can be renewed every time of activation, and the accuracy of detection of alteration by “spoofing” can be improved.

  Note that, when n encryption keys K prepared in advance in the key memory 10 are used, there is an advantage that it is possible to save the trouble of generating each time of activation.

The alteration of the header information D _HE, if falsification of the image data D _1, or the tampering by "spoofing" is detected, the detected field number working memory types and falsification of their tampering (predetermined storage unit) 9 and / or displayed on the monitor 22, the detection result of tampering can be saved and / or the user can be immediately notified by the monitor.

For each field 58 of the header-attached image data D ₂ , the first hash value generation means 40, the second hash value generation means 41, the first encrypted data generation means 42, and the hash value / encryption data addition means 43 are sequentially arranged. Since the processing of each means is performed, it is suitable for recording image data in the image storage device 21 in real time.

For each field 58 of the recording image data D _3, a third hash value generation unit 45, a fourth hash value generation unit 46, a first comparison unit 48, a first determination unit 49, and a second comparison unit 50 are provided. The second determination means 51, the second encrypted data generation means 47, the encrypted data comparison means 52, and the encrypted data determination means 53 are processed in this order, so that they are read from the image storage device 21 in real time. the image data D ₃ issued is suitable for the detection of tampering.

1 is a schematic configuration diagram of an image recording apparatus 20 according to Embodiment 1. FIG. It is a figure for demonstrating the image data temporarily preserve | saved in the image memory 5 of FIG. FIG. 2 is a schematic configuration diagram (a diagram illustrating functional blocks) of a control processing unit 4 in FIG. 1. It is the figure which showed typically the operation | movement at the time of the image recording of the image recording apparatus 20 of FIG. It is the figure which showed typically the image data accumulate | stored in the image storage apparatus 21 of FIG. 3 is a flowchart for explaining an operation at the time of image recording of the image recording apparatus 20 of FIG. 1. It is the figure which showed typically the operation | movement at the time of the tampering detection of the image recording apparatus 20 of FIG. 3 is a flowchart for explaining an operation at the time of tampering detection of the image recording apparatus 20 of FIG. 1.

Explanation of symbols

1 video signal input terminal, 2 NTSC decoder, 3 image compression processing unit, 4 control processing unit, 5 image memory, 6 video signal information input terminal, 7 CPU (central processing unit), 8 program memory, 9 working memory, 10 Key memory, 11 instruction input unit, 12 image expansion processing unit, 13 NTSC encoder, 14 synthesis processing circuit, 15 video signal output terminal, 16 image data input / output terminal, 20 image recording device, 21 image storage device, 22 monitor, 40 First hash value generation means, 41 2nd hash value generation means, 42 1st encryption data generation means, 43 hash value / encryption data addition means, 44 recording means, 45 3rd hash generation means, 46 4th Hash value generation means, 47 second encrypted data generation means, 48 first comparison means, 49 first determination means, 50 second Comparison means, 51 second determination means, 52 encrypted data comparison means, 53 encrypted data determination means, 54 determination result output means, 58 one-field image data, 61, 61a,..., 61e first hash value, 62, 62e second hash value, 63, 63a, ..., 63e first encrypted data, 65, 65a, ..., 65e third hash value, 66, 66a, ..., 66e second hash value, 67, 67a, ..., 67e second encrypted data, D ₀ image data, D ₁ compressed image data, D ₂ with headers image data, D ₃ for recording image data, D ₄ decompressed image data, D _HE header information , S _PI analog video signal, an analog video signal including the information of S _O tampering detection result.

Claims (9)

An image recording device for recording image data in a predetermined image storage device,
A key memory for storing the encryption key;
Header-attached image data creating means for creating header-attached image data from the image data;
First hash value generation means for generating a first hash value from the header information for each field of the header-attached image data;
Second hash value generation means for generating a second hash value by linking to generation of the first hash value from the image data for each field of the header-attached image data;
First encrypted data generating means for generating first encrypted data from the second hash value and the encryption key output from the key memory;
A hash value / encrypted data adding means for creating recording image data by adding the first hash value, the second hash value, and the first encrypted data to a field of their generation source;
Recording means for recording the image data for recording created by the hash value / encrypted data adding means in a predetermined image storage device;
Third hash value generation means for generating a third hash value from the header information for each field of the recording image data read from the predetermined image storage device;
First comparing means for comparing the third hash value and the first hash value added to the field of the generation thereof;
First determination means for determining whether or not the header information of the field is falsified based on the comparison result of the first comparison means;
For each field of the recording image data read from the predetermined storage device, a fourth hash value is generated by linking to the generation of the third hash value from the image data. Generating means;
A second comparing means for comparing the fourth hash value and the second hash value added to the field from which the fourth hash value is generated;
Second determination means for determining the presence or absence of falsification of the image data of the field based on the comparison result of the second comparison means;
Second encrypted data generating means for generating second encrypted data from the fourth hash value and the encryption key output from the key memory;
Encrypted data comparing means for comparing the second encrypted data with the first encrypted data added to the field from which the fourth hash value used for generating the second encrypted data is generated;
Based on the comparison result of the encrypted data comparing means, the encrypted data determining means for determining whether or not the field is falsified by “spoofing”;
An image recording apparatus comprising: The image recording apparatus according to claim 1,
The key memory stores n different encryption keys, associates each field with the encryption key one by one, and changes the encryption key in a predetermined circulation order for each field. And the n encryption keys are selectively output to the first encrypted data generating means. The image recording apparatus according to claim 2,
The key memory associates the encryption keys with the fields one by one, changes the encryption keys in the predetermined circulation order for each field, and converts the n encryption keys to the n keys. An image recording apparatus that selectively outputs to the second encrypted data generation means. The image recording apparatus according to claim 2,
The second encrypted data generation means reads the n encryption keys from the key memory, generates n second encrypted data for the n encryption keys,
The encrypted data comparing means compares each of the n second encrypted data with the first encrypted data,
The encrypted data judging means, if the result of the comparison by the encrypted data comparing means is that there is a match with the first encrypted data in the n second encrypted data, If it is determined that there is no tampering by “Sustain”, and none of the n second cipher data matches the first cipher data, the field is tampered with “spoofing”. It is determined that there is
When there is a key memory that matches the first encrypted data among the n second encrypted data, the key memory can generate the matched second encrypted data according to the predetermined circulation order. An image recording apparatus, wherein the n encryption keys are selectively output to the second encrypted data generation means from the encryption key next to the used encryption key. The image recording apparatus according to claim 2,
The n recording keys are generated by generating a random number at the time of activation, and an image recording apparatus. The image recording apparatus according to claim 2,
The n number of encryption keys are prepared in advance in the key memory. The image recording apparatus according to claim 1,
When the first determination unit, the second determination unit, and the encrypted data determination unit determine that the header information has been falsified, the image data has been falsified, and the “spoofing” has falsified, respectively, An image recording apparatus, further comprising: a determination result output unit that stores the type of the field and the falsified field number in a predetermined storage unit and / or displays the field number on a predetermined monitor. The image recording apparatus according to claim 1,
For each field of the header-attached image data, the first hash value generating means, the second hash value generating means, the first encrypted data generating means, and the hash value / encrypted data adding means are arranged in this order. The image recording apparatus is characterized in that the process is performed. The image recording apparatus according to claim 1,
For each field of the recording image data, the third hash value generation means, the fourth hash value generation means, the first comparison means, the first determination means, the second comparison means, 2. An image recording apparatus according to claim 1, wherein the processing of each means is performed in the order of second determination means, second encryption data generation means, encryption data comparison means, and encryption data determination means.

Images