KR101930676B1 - CCTV image encryption method - Google Patents

Abstract

A CCTV image encoding method according to an embodiment of the present invention comprises: (a) an image acquisition step of acquiring an image by photographing the image using a CCTV; (b) a pixel extraction step of extracting 8X8 spatial pixels from the acquired image; (c) a first conversion step of DCT-converting the extracted pixels; (d) a second conversion step of applying a threshold value (T=0) to the DCT-converted result value in the first conversion step; (e) a quantization step of performing quantization on the result obtained by performing the second conversion step; (f) a block data acquisition step of acquiring block data by scanning the quantized result through a zigzag scanning scheme; and (g) an encoding step of encoding the acquired block data. According to the present invention, the step (g) encodes only first block data (data having the largest entropy) among the acquired block data.

Description

CCTV image encryption method

The present invention relates to a CCTV image encryption method, and more particularly, to a CCTV image encryption method for encrypting only the block data having the largest entropy of the acquired image block data, thereby preventing the decryption of the block data as much as possible, thereby enhancing security.

In general, image processing is performed by compressing and transmitting an image, thereby improving the transmission efficiency of the image.

On the other hand, as the voices of protection for digital image data have increased in domestic and foreign countries, research and development are being actively carried out to prevent illegal distribution and reproduction of video images.

In addition, an image may be output to the outside of the system or an encryption operation may be performed on an image requiring security. In this case, there is a problem that a long time is required for the encryption operation.

In particular, the conventional encryption method can be encrypted by encrypting the entire frame or selectively encrypting one or more block data.

However, the above-mentioned method of encrypting the entire frame has a problem that more time and resources are consumed, resulting in performance degradation such as the speed of the system.

Accordingly, the method of randomly selecting and encrypting one or more block data, which is an improved method, has contributed to system performance, but can be performed by selecting one or more block data without considering entropy and data capacity change, There was a problem that could not be optimized for system performance.

Therefore, there is a need for a technique capable of improving the above problems.

Korean Patent Registration No. 10-0468844 is presented as a conventional technique.

The present invention, which is devised to remedy the above problem, is to provide a CCTV image encryption method for encrypting only the block data having the largest entropy among block data of an acquired image, thereby preventing the decryption of block data as much as possible and enhancing security.

A CCTV image encrypting method according to an embodiment of the present invention for solving the above problem (a) an image capturing step of capturing an image by CCTV; (b) extracting 8x8 spatial pixels from the acquired image; (c) a first conversion step of performing DCT on the extracted pixels; (d) applying a threshold (T = 0) to the DCT-transformed result in the first transforming step; (e) a quantization step of performing quantization on the result obtained through the second conversion step; (f) obtaining a block data by scanning the quantized result by a zigzag scanning method, and (g) encrypting the obtained block data, wherein the step (g) Only the first block data (data having the largest entropy) among the first block data is encrypted.

In addition, the image obtained in the step (a) is an I frame among the I, B and P frame types.

In the step (e), quantization is performed by applying? = 0.5.

In addition, after step (g), (1) a compression step of acquiring a compressed bitstream by applying a DC / AC codeword table to the encrypted block data, and (2) The method comprising the steps of:

The step (g) may be performed by using a private key or a public key.

In addition, in the step (2), when storing the compressed data using the NVR technology, a negative integer or a positive integer value is selectively selected and binarized from a compressed bitstream obtained from a user terminal equipped with an interlocking app, Added or subtracted, and then the encrypted data is stored.

In addition, the CCTV is further provided with a sticky beacon capable of short-range communication.

In addition, when a user terminal equipped with an application capable of interlocking within the provided beacon area approaches the beacon service server, the service server of the beacon operates the application of the user terminal, and a negative integer or positive An integer value, and an applied addition or subtraction operation symbol on the screen.

The CCTV image encryption method according to the embodiment of the present invention can enhance security by preventing only the block data having the largest entropy from the block data of the acquired image by encrypting the block data.

Further, the change in data capacity after encryption can be small.

Also, it does not cause any problems in system performance (speed).

In addition, encryption can be performed quickly.

1 is a diagram illustrating a flow of a CCTV image encryption method according to an embodiment of the present invention.
2 is a flowchart illustrating a CCTV image encryption method according to an embodiment of the present invention.
3 is a diagram showing reception of decoded information using a beacon and a user terminal and an example of a user terminal screen.

Hereinafter, the description of the present invention with reference to the drawings is not limited to a specific embodiment, and various transformations can be applied and various embodiments can be made. It is to be understood that the following description covers all changes, equivalents, and alternatives falling within the spirit and scope of the present invention.

In the following description, the terms first, second, and the like are used to describe various components and are not limited to their own meaning, and are used only for the purpose of distinguishing one component from another component.

Like reference numerals used throughout the specification denote like elements.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. It is also to be understood that the terms " comprising, "" comprising, "or" having ", and the like are intended to designate the presence of stated features, integers, And should not be construed to preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted in an ideal or overly formal sense unless expressly defined in the present application Do not.

In the following description of the present invention with reference to the accompanying drawings, the same components are denoted by the same reference numerals regardless of the reference numerals, and redundant explanations thereof will be omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2.

A CCTV image encryption method according to an embodiment of the present invention includes an image acquisition step (S100) of capturing an image by CCTV, a pixel extraction step (S200) of extracting 8X8 spatial pixels from the acquired image, a DCT A second transforming step S400 of applying a threshold value (T = 0) to the resultant DCT transformed in the first transforming step S300, and a second transforming step S400 of quantizing the result obtained by the second transforming step A block data acquiring step (S600) for obtaining block data by scanning the quantized result by a zigzag scanning method, and an encryption step (S700) for encrypting the obtained block data.

Specifically, each step will be described. In step S100, an image acquiring step of acquiring an image by capturing with a CCTV, a conventional or later-planned CCTV camera device capable of storing shooting data in real time can be used. Can be obtained.

There are GOP (Group Of Pictures) as a basic instruction for knowing key frames, and a basic option of MPEG - 1/2 encoding means collection from key frame to next key frame.

At this time, as a kind of the frame obtained in the present invention, an I frame out of I, B and P frames can be used as a key frame.

An I frame is an abbreviation of Intra Frame, which means a key frame. It has the best image quality and the largest capacity.

The P frame is an abbreviation of Predicted Frame. It is composed of information of the key frame which is derived from the previous frame, and the picture quality and the capacity are medium.

A B frame is an abbreviation of Bidirectional Frame and means a frame formed based on information of I / P frames before and after. Picture quality and capacity are the smallest.

That is, a P frame is inserted between I frames, and a B frame is inserted between the I frame and the P frame. The I frame to the next I frame are grouped into one GOP, and the frame number of this bundle becomes the size of the GOP.

Here, the I frame means an actual image, and the process proceeds to step S200, where 8X8 spatial pixels are extracted.

At this time, extracting 8x8 spatial pixels is defined in the h.254 standard, and is used only in the present invention.

In operation S300, the pixel extracted in operation S200 is DCT-transformed. Specifically, DCT ( Discrete Cosine Transform ) is also referred to as a discrete cosine transform, and is a technique for compressing an image using only a frame (I frame).

It is mainly used for JPEG compression.

When the image is DCT-transformed, as shown in FIG. 1, the spatial domain is changed to the frequency domain, and the data (signal) is converged to the lower frequency, which is referred to as an 'energy concentration phenomenon.'

The reason for performing the DCT is as follows. When the 8 × 8 block is DCT, the same color among the 64 pixels is driven to a low frequency (DC), and when there is a change in color, the high frequency (AC) is positioned.

At this time, the color average value of the 8 × 8 block becomes the DC component, and the AC component is different from the remaining average value.

It can be seen from the eye that the value of DC is very high, which means that the value of DC is large because the adjacent pixels have almost the same color.

However, human eyes are also sensitive to low frequency components (DC), but because they are not sensitive to high frequency components (AC), they do not feel any difference in image quality even if a high frequency range is omitted.

In other words, DCT is a task of changing frequency components before proceeding with compression.

Next, S400 is a second conversion step of applying a threshold value (T = 0) to the DCT-transformed resultant value. In many cases, the resultant DCT transformed value has a value of almost 0, It is compared with the set threshold value and quantized and encoded in the case of a transform coefficient equal to or larger than the threshold value, and if not, it can be processed as all zeros.

The quantization will be described below.

Next, step S500 is a quantization step for quantizing the result obtained in step S400, and will be described in detail below.

Quantization is the process of transforming a sample value into a digital signal with a minimum unit value that can no longer be quantified.

In other words, you can make infinite amounts of analog information at intervals that can count, and use only meaningful information.

At this time, quantization can be performed by applying a target bit rate or? = 0.5, which is a weight for buffer control.

After quantization, difference information is coded to obtain a DC coefficient.

Next, step S600 is a block data acquisition step of obtaining block data by scanning the quantized result by the zigzag scanning method.

By scanning with the zigzag scanning method, an AC coefficient can be obtained.

When AC is quantized, 0 is very large, and in particular, a high frequency coefficient is likely to be zero. In order to effectively reduce such statistical properties, a zigzag scanning method is applied. In this method, the AC coefficients can be aligned so that the values of consecutive zeros increase in the order of low energy concentration.

In other words, 123456789 when making a value like 123, and 147258369 when making the same value as one line like 456. In case of making a value like 789 one line, when it is 124357689, a high value on the left side If the AC quantization is performed, a large value is generated at the upper left corner.

Therefore, in the order of 1, 2, 4, 3, 5, 7, 6, 8 and 9, a larger value is placed ahead of the smaller value (0) The advantage is that you can sort the AC coefficients.

Next, the step S700 is an encryption step of encrypting the obtained block data, and encrypts only the first block data (data having the largest entropy) of the obtained block data.

That is, an algorithm is applied to encode only the portion of the block data arranged in the zigzag scanning method that has the largest energy (the largest entropy) in the forefront of the aligned block data.

Therefore, the encryption time is shorter than that of the conventional method of encrypting the entire frame, and the loss of performance of the system can be reduced accordingly.

In addition, when the image is restored without decryption, an image that can not be recognized is output, thereby enhancing the security against leakage and illegal dissemination of the image.

In addition, there is an advantage in that, when an I frame having a large data capacity is encrypted, a change in data capacity, which may be damaged, is also small.

At this time, it is possible to encrypt by applying the encryption method of the private key or the public key.

A private key or a public key is called a public key cryptosystem, and allows users who have not previously divided the secret key to communicate securely.

There is a public key and a secret key, and anyone can know the public key, but the corresponding secret key must be known only to the owner of the key.

This is also referred to as asymmetric encryption.

Next, the CCTV image encryption method of the present invention includes a compressing step (S800) of obtaining a compressed bitstream by applying a DC / AC codeword table to the encrypted block data, and a step of storing the compressed data by applying NVR technology (S900).

More specifically, the step S800 may be entropy-encoded by using a Huffman codeword table.

That is, the DC coefficient and the AC coefficient obtained in the above are applied to the Huffman codeword table and the DC Huffman codeword and the AC Huffman codon codeword, respectively, to obtain a compressed bitstream.

The compressed bit stream after encryption can be stored by applying the NVR technique.

The above-described steps are performed in CCTV, and can be performed in real time.

Next, the user terminal 100 and the beacon 11, which are configured to enable the administrator to proceed even during the mobile communication through the wireless communication, and to allow the user to proceed from the double encryption to the decryption step, will be further described.

When a compressed bitstream is stored by applying NVR technology, a negative integer or a positive integer value is selectively selected from a compressed bitstream obtained from the user terminal 100 in which an interlocking app is installed, and added or subtracted by binary addition And then stored.

The user terminal 100 is a terminal possessed by the administrator who proceeds with the CCTV image encryption step so that the user terminal 100 can proceed remotely while moving the step. In the present invention, the terminal uses a mobile communication terminal Explain it mainly.

Specifically, the encrypted image is encrypted and stored, thereby making it difficult to decrypt the CCTV 10 image. Thus, it is possible to make it difficult for a person other than the person concerned to decrypt the encrypted CCTV 10 image.

In addition, since the administrator himself or herself selects a positive integer or a positive integer value and applies addition or subtraction, only the best administrator among the administrators has the correct encryption information, thereby preventing a password leakage accident from occurring inside the manager It is also possible.

In addition, the CCTV 10 may further include a sticky beacon 11 capable of short-distance communication, which may be a configuration associated with the contents of the interaction with the user terminal 100. [

The sticky beacon 11 may be attached to a small camera such as the CCTV 10 of the present invention to form a beacon region P since the sticky beacon 11 is made of a coin size that can be attached to any object.

At this time, the beacon 11 refers to a short range wireless communication device based on a Bluetooth 4.0 (BLE) protocol and can communicate with devices within a maximum distance of 70 m.

3, when a user terminal 100 installed with an application capable of interlocking in a beacon area P accesses, the CCTV 10 connected to the service server 11a of the beacon detects the beacon area P, The application of the user terminal 100 may be operated (for example, push notification) and a binary negative integer or a positive integer value and an addition or subtraction operation symbol may be exposed on the screen to double-encrypt the application.

That is, the user terminal 100 is given a unique ID stored in the service server 11a of the beacon, accesses the beacon area P, and matches the unique ID stored in the service server 11a of the beacon, (For example, a push notification) is transmitted from the CCTV so that the binarized negative integer or positive integer value and the addition or subtraction operation symbol are exposed on the screen in order to double-encrypt the decryption information , And only the administrator who owns the user terminal 100 can decode the double encrypted CCTV (10) video using the user terminal 100.

Thereafter, the decryption method may be interlocked with the CCTV 10 using an application installed in the user terminal 100. [

Therefore, when decryption is required, it is possible to receive decryption information using the beacon 11.

The embodiments of the present invention described above are not implemented only by the apparatus and / or method, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention, a recording medium on which the program is recorded And such an embodiment can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

P: beacon area
10: CCTV
11: Beacon
11a: beacon's service server
100: user terminal

Claims (8)

(a) an image acquiring step of acquiring an image by photographing by CCTV;
(b) extracting 8x8 spatial pixels from the acquired image;
(c) a first conversion step of performing DCT on the extracted pixels;
(d) applying a threshold (T = 0) to the DCT-transformed result in the first transforming step;
(e) a quantization step of performing quantization on the result obtained through the second conversion step;
(f) a block data obtaining step of obtaining block data by scanning the quantized result by a zigzag scanning method and
(g) encrypting the obtained block data,
The step (g)
Encrypts only the first block data (data having the largest entropy) of the obtained block data,
After the step (g)
(1) a compression step of obtaining a compressed bit stream by applying a DC / AC codeword table to encrypted block data and
(2) storing compressed data by applying NVR technology,
The step (2)
When the compressed data is stored using the NVR technology, a negative integer or a positive integer value is selectively selected from a compressed bitstream obtained from a user terminal equipped with an interlocking application, and the binary bitstream is binarized, added or subtracted, , ≪ / RTI >
The CCTV is further provided with a sticky beacon capable of short-
When a user terminal equipped with an app capable of interlocking in a beacon area is accessed, a service server of the beacon that senses the beacon activates the application of the user terminal and encodes the encoded negative integer or positive integer value, And exposes the applied addition or subtraction operation symbols on the screen.

The method according to claim 1,
Wherein the image obtained in step (a) is an I frame among I, B, and P frame types.
The method according to claim 1,
The step (e)
? = 0.5 is applied to quantize the CCTV image.
delete The method according to claim 1,
The step (g)
And encrypting the encrypted data using a private key or a public key.
delete delete delete

Images