KR20070121487A - Encoding and decoding apparatus having selective encryption function of h.264/avc multimedia contents and its method - Google Patents

Abstract

An encoding and decoding apparatus having a selective encryption function of H.264/AVC(Advanced Video Coding) multimedia contents and a method thereof are provided to prevent an unallowable anonymous user from playing the H.264/AVC multimedia contents by selectively encrypting/decoding the multimedia contents, thereby improving rights of a copyrighter by preventing arrogation of content provider's right such as unauthorized copying of contents, and forming a rational digital contents providing market. An arbitrary discrete cosine transform coefficient generator(120) generates an arbitrary discrete cosine transform coefficient to encrypt an integer type discrete cosine transform coefficient of a video converted by an integer type discrete cosine transform unit based on an initial value. An encryption unit(130) uses the arbitrary discrete cosine transform coefficient, generated by the arbitrary discrete cosine transform coefficient generator, as an encryption key. The encryption unit encrypts the integer type discrete cosine transform coefficient of the video converted by the integer type discrete cosine transform unit by performing addition or subtraction of the integer type discrete cosine transform coefficient and the encryption key, and transfers the encrypted integer type discrete cosine transform coefficient to a quantization unit. A CABAC(Context Adaptive Binary Arithmetic Coding) table generator(150) generates a CABAC initialization table necessary for entropy coding. An encoder(160) performs entropy coding of the quantization value quantized by the quantization unit by using the CABAC initialization table value generated by the CABAC table generator.

Description

[Encoding and decoding apparatus having selective encryption function of H.264 / AVC multimedia contents and its method}

1 is an overall configuration diagram of an encoding apparatus having a selective encryption function of H.264 / AVC multimedia content according to the present invention;

2 is a block diagram of an embodiment of an apparatus for selectively decoding H.264 / AVC multimedia content according to the present invention;

3 is a flowchart illustrating a method of encoding H.264 / AVC multimedia content according to the present invention;

4 is a flowchart illustrating a method of decoding H.264 / AVC multimedia content according to the present invention.

* Explanation of symbols on the main parts of the drawing

110: integer discrete cosine transform unit

120: Discrete Discrete Cosine Transform Coefficient Generator

130: discrete cosine transform coefficient encryption unit 140: quantization unit

150: CABAC table generation unit 160: code unit

170: inverse quantization unit 180: inverse discrete cosine transform unit

190: motion estimation predictor 200: motion estimation unit

210: CABAC table generation unit 220: decoding unit

230: inverse quantization

240: Discrete Discrete Cosine Transform Coefficient Generator

250: Discrete cosine transform coefficient decoder 260 Inverse discrete cosine transform unit

270: motion estimation predictor

The present invention relates to an encoding and decryption apparatus and a method for selectively encrypting H.264 / AVC multimedia contents, and more particularly, to an H.264 / AVC (MPEG-4 Part 10) based multimedia content compression region. The present invention relates to an encoding and decryption apparatus having a selective encryption function of H.264 / AVC multimedia content, and a method thereof, to provide a selective encryption / decryption technique capable of efficiently encrypting / decrypting in.

As the digital content market grows, multimedia security and content protection are emerging as important issues. In particular, a new encryption / decryption algorithm for multimedia content is indispensable due to the characteristics of various types of multimedia contents. In addition, as the market demand for high quality video applications such as Internet Protocol Television (IPTV) and Video on Demand (VOD) increases, an effective encryption technique of video data is essential.

To date, many video encryption techniques have been studied and published, but most of them only deal with conventional video standards such as Moving Picture Experts Group-1 (MPEG-1) and Moving Picture Experts Group-2 (MPEG-2). Because of the limitations, new algorithms are required that can selectively and effectively encrypt / decrypt multimedia data using the features of the latest video compression techniques such as MPEG-4 Part 10 Advanced Video Coding (AVC). In addition, there is a need for a real-time encryption technique that is indispensable for real-time broadcasting.

In order to solve the above encryption / decryption problem and to meet the demand, the prior art digital content protection / management system encrypts all of the digital content or transmits a portion necessary for reproduction in the encrypted state, and encrypts the encryption content. The digital content execution device that receives the received content receives a decryption key necessary for decryption in advance or, if necessary, decrypts and reproduces the encrypted content.

Such a content encryption method has a problem that broadcast viewers do not satisfy the practical necessity because virtually many restrictions are placed on watching real-time broadcast such as 'On Air'.

In addition, in order to view broadcast or recorded multimedia contents, it is necessary to decrypt encrypted contents and play contents encoded in various formats. In order to do this, a player with strong computational performance is required. There is a problem that can increase the burden.

The present invention has been proposed to solve the above problems, and provides an optional encryption / decryption technique capable of efficiently encrypting / decrypting H.264 / AVC (MPEG-4 Part 10) based multimedia contents in a compressed area. An object of the present invention is to provide an encoding and decryption apparatus and a method for selectively encrypting H.264 / AVC multimedia contents.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The present invention for achieving the above object, An image encoding apparatus comprising an integer discrete cosine transform means and a quantization means, generating an arbitrary discrete cosine transform coefficient to encode an integer discrete cosine transform coefficient of an image transformed by the integer discrete cosine transform means based on an initial value. Arbitrary discrete cosine transform coefficient generating means; Using the discrete discrete cosine transform coefficients generated by the arbitrary discrete cosine transform coefficient generating means as an encryption key, the integer discrete cosine transform coefficients of the image converted by the integer discrete cosine transform means and the encryption key are added or subtracted to the integer discrete. Encryption means for encrypting the integer discrete cosine transform coefficients of the image converted by the cosine transform means, and transferring the encrypted integer discrete cosine transform coefficients to the quantization means; CABAC table generation means for generating a CABAC initialization table necessary for entropy coding; And encoding means for entropy coding the quantized value quantized by the quantization means using the CABAC initialization table value generated by the CABAC table generating means.

The present invention also provides a CABAC for generating a CABAC (Context Adaptive Binary Arithmetic Coding) initialization table for entropy decoding of an encrypted content (video) in an image decoding apparatus including an inverse quantization means and an inverse discrete cosine transform means. Table generating means; Decoding means for entropy decoding an integer discrete cosine transform coefficient of an encrypted image by using the CABAC initialization table value generated by the CABAC table generating means and transmitting the entropy decoding coefficient to the inverse quantization means; Arbitrary discrete cosine transform coefficient generating means for generating an arbitrary discrete cosine transform coefficient to decode the integer discrete cosine transform coefficient dequantized by the inverse quantization means based on an initial value; And using the discrete discrete cosine transform coefficients generated by the arbitrary discrete cosine transform coefficient generating means as a decoding key, adding and subtracting the integer discrete cosine transform coefficient dequantized by the inverse quantization means and the decoding key to the dequantization means. And decoding means for decoding the inverse quantized integer discrete cosine transform coefficients and transferring the decoded integer discrete cosine transform coefficients to the inverse discrete cosine transform coefficient means.

Meanwhile, in the H.264 / AVC-based image encoding method, the present invention provides arbitrary discrete cosine transform coefficients to encode integer discrete cosine transform coefficients of an image converted by integer discrete cosine transform means based on an initial value. Generating a first step; By using the discrete discrete cosine transform coefficient generated in the first step as an encryption key, the integer discrete cosine transform coefficient of the image converted by the integer discrete cosine transform means and the encryption key are added or subtracted by the integer discrete cosine transform means. Encrypting an integer discrete cosine transform coefficient of the transformed image and transferring the encrypted integer discrete cosine transform coefficient to the quantization means; Generating a context adaptive binary arithmetic coding (CABAC) initialization table required for entropy coding; And a fourth step of entropy coding the integer discrete cosine transform coefficients quantized by the quantization means using the CABAC initialization table value generated in the third step.

In addition, the present invention provides an H.264 / AVC-based video decoding method comprising: a first step of generating a CABAC initialization table necessary for entropy decoding of an encrypted content (video); A second step of entropy decoding an integer discrete cosine transform coefficient of an encrypted image by using the CABAC initialization table value generated in the first step and transferring it to inverse quantization means; Generating a random discrete cosine transform coefficient to decode an integer discrete cosine transform coefficient dequantized by the inverse quantization means based on an initial value; And an integer type inversely quantized by the inverse quantization means by adding or subtracting the integer discrete cosine transform coefficient inversely quantized by the inverse quantization means and the decoding key using the arbitrary discrete cosine transform coefficients generated in the third step as a decoding key. And a fourth step of decoding the discrete cosine transform coefficients and transferring the decoded integer discrete cosine transform coefficients to inverse discrete cosine transform coefficient means.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Note that the encryption key and the decryption key in the present invention can be set in various forms by the user.

1 is an overall configuration diagram of an encoding apparatus having a selective encryption function of H.264 / AVC multimedia content according to the present invention.

As shown in FIG. 1, an encoding apparatus having a selective encryption function of H.264 / AVC multimedia content according to the present invention may perform discrete cosine conversion of H.264 / AVC multimedia content (video in macroblock units) into an integer. Integer Discrete Cosine Transform (Integer Discrete Cosine Transform) Integer Discrete Cosine Transformation DCT) an arbitrary discrete cosine transform coefficient generator 120 for generating an arbitrary integer discrete cosine transform (DCT) coefficient based on an initial value given by a user to encrypt the coefficient, and an arbitrary discrete cosine transform coefficient generator 120 Integer Discrete Cosine Transform (DCT) obtained by the Integer Discrete Cosine Transformation Unit 110 using an arbitrary discrete cosine transform (DCT) coefficient generated by A discrete cosine transform coefficient encryption unit 130 for encoding coefficients, a quantization unit 140 for quantizing integer discrete cosine transform (DCT) coefficients encrypted by the encryption unit 130, and H.264 / AVC multimedia content. The CABAC table generator 150 generates a CABAC initialization table for entropy coding for compression, and the CABAC table generator converts the integer discrete cosine transform (DCT) coefficients quantized by the quantizer 140. A coder 160 for entropy coding according to the value of the CABAC initialization table generated at 150, an inverse quantizer 170 for inversely quantizing integer discrete cosine transform (DCT) coefficients quantized by the quantizer 140, and Inverse Discrete Cosine Transformation (180) for Inverse Discrete Cosine Transform (DCT) Inverse Discrete Cosine Transform (DCT) Coefficients Inversely Quantized by Inverse Quantizer 170, Inverse Discrete Cosine Transformation (180) A motion estimation predictor 190 that calculates a motion vector of the image through motion estimation with an integer transformed (DCT) integer discrete cosine transform (DCT) coefficient, and a motion vector of the image calculated by the motion estimation predictor 190. And a motion estimator 200 to obtain a differential image by estimating motion using the data.

Here, when the integer discrete cosine transform unit 110 receives an image (H.264 / AVC multimedia content) in units of macroblocks, an integer discrete cosine transform (DCT) is used for macroblocks of frames of H.264 / AVC multimedia content. Transform to generate integer discrete cosine transform (DCT) coefficients of 8 × 8 or 4 × 4 macroblocks, which are decomposed into frequency bands, and store the generated discrete discrete cosine transform (DCT) coefficients in a temporary buffer.

The temporary discrete cosine transform coefficient generator 120 may have an arbitrary value based on an initial value generated by a user to encrypt the integer discrete cosine transform (DCT) coefficient obtained by the integer discrete cosine transform unit 110. Generate an integer matrix (any integer discrete cosine transform (DCT) coefficients) of × 8 or 4 × 4 macroblocks.

The discrete cosine transform coefficient encryptor 130 uses an integer matrix (any integer discrete cosine transform (DCT) coefficient) having an arbitrary value generated by the arbitrary discrete cosine transform coefficient generator 120 as an encryption key, and is integer discrete. The integer discrete cosine transform (DCT) coefficients of the 8 × 8 or 4 × 4 macroblocks generated by the cosine transform unit 110 and arbitrary integer discrete cosine transform (DCT) coefficients are added or subtracted from the integer discrete cosine transform unit 110. Encrypt the integer discrete cosine transform (DCT) coefficients of the generated 8 × 8 or 4 × 4 macroblocks, and replace the sign bits in any order according to the encryption key (arbitrary integer discrete cosine transform (DCT) coefficients). Store in a buffer.

The quantization unit 140 quantizes the encoded discrete cosine transform (DCT) coefficients to generate a reference image (H.264 / AVC multimedia content to be referred to) for P-Frame or B-Frame in H.264 / AVC. .

The inverse quantization unit 170 and the inverse discrete cosine transform unit 180 reconstruct the image to be referenced by inverse quantization and inverse discrete cosine transform (DCT) of the quantized coefficients.

The motion estimation predictor 190 calculates a motion vector of the image through motion estimation with the image to be compressed, and the motion estimator 200 uses the motion vector calculated by the motion estimation predictor 190 to estimate the motion estimation. To obtain the differential image (H.264 / AVC multimedia content).

In the case of H.264 / AVC main profile, entropy coding is performed using CABAC, unlike conventional Huffman coding. In the case of CABAC, initial probability values are defined in the initialization table for each context. By changing the defined values, it is impossible to interpret an image encoded using H.264 / AVC.

In this case, the CABAC initialization table consists of a matrix of two coefficients (m, n), where each value of m, n has a precomputed probability value of a specific context.

The CABAC table generator 150 generates a new CABAC initialization table value by adding a new pair of values generated using the encryption key to the coefficient pair of the CABAC initialization table.

The encoder 160 encodes the encrypted integer discrete cosine transform (DCT) coefficients by replacing the two coefficients of the new CABAC initialization table thus obtained with an initial probability, and then uses a file or streaming server to encode the client. Send to.

2 is a configuration diagram of an apparatus for selectively decoding H.264 / AVC multimedia content according to the present invention.

As shown in FIG. 2, the apparatus for selectively decrypting H.264 / AVC multimedia content according to the present invention generates a CABAC initialization table for generating entropy decoding for decompressing encrypted H.264 / AVC multimedia content. Decoder for entropy decoding the integer discrete cosine transform (DCT) coefficients of the encrypted H.264 / AVC multimedia content using the table generator 210 and the CABAC initialization table values generated by the CABAC table generator 210. (220), an inverse quantization unit 230 for inverse quantization of an integer discrete cosine transform (DCT) coefficient entropy decoded by the decoder 220, and an integer discrete cosine transform (DCT) inversely quantized by the inverse quantization unit 230. A random discrete cosine transform coefficient generator 240 for generating an arbitrary integer discrete cosine transform (DCT) coefficient based on an initial value generated by a user to decode the coefficient; Discrete cosine transforming an inverse quantized integer discrete cosine transform (DCT) coefficient by inverse quantization unit 230 using an arbitrary discrete cosine transform (DCT) coefficient generated by random discrete cosine transform coefficient generator 240 as a decoding key A transform coefficient decoder 250, an inverse discrete cosine transform unit 260 for inverse discrete cosine transform (DCT) the integer discrete cosine transform (DCT) coefficients decoded by the discrete cosine transform coefficient decoder 250, and an inverse discrete The cosine transformer 260 includes a motion estimation predictor 270 that calculates a motion vector of an image through motion estimation with an integer discrete cosine transform (DCT) coefficient obtained by inverse discrete cosine transform (DCT).

Here, the temporary discrete cosine transform coefficient generator 240 has an arbitrary value based on an initial value generated by a user to decode the integer discrete cosine transform (DCT) coefficient inversely quantized by the inverse quantizer 230. Generate an integer matrix (any integer discrete cosine transform (DCT) coefficients) of 8x8 or 4x4 macroblocks.

The discrete cosine transform coefficient decoder 250 uses an integer matrix (any integer discrete cosine transform coefficient) having an arbitrary value generated by the arbitrary discrete cosine transform coefficient generator 240 as a decryption key. Inversely, the dequantized integer discrete cosine transform (DCT) coefficients and any integer discrete cosine transform (DCT) coefficients are added or subtracted by the inverse quantizer 230 to dequantize the integer discrete cosine transform ( DCT) coefficients are decoded, and the sign bits are replaced and stored in a buffer in an arbitrary order according to the decryption key (any integer discrete cosine transform (DCT) coefficient).

3 is a flowchart illustrating a method of encoding H.264 / AVC multimedia content according to the present invention.

First, the selective encryption apparatus for H.264 / AVC multimedia content is set by the user in the initialization step to encrypt the integer discrete cosine transform (DCT) coefficient of the input macroblock unit image (H.264 / AVC multimedia content). Using an initial value, an integer matrix (an integer discrete cosine transform (DCT) coefficient) of 8x8 or 4x4 macroblocks is arbitrarily generated (301).

Subsequently, the selective encryption apparatus for H.264 / AVC multimedia content converts the image of the macroblock unit (H.264 / AVC multimedia content) into integer discrete cosine transform (DCT) and decomposes it into 8 × 8 or 4 × An integer discrete cosine transform (DCT) coefficient of the macroblock is generated and the generated integer discrete cosine transform (DCT) coefficient is stored in a temporary buffer (302).

In this case, in the case of H.264 / AVC, macroblocks are divided into 8 × 8 or 4 × 4 sizes for each frame of the image, and the divided macroblocks are each pixel value of the image through integer discrete cosine transform (DCT). Perform frequency conversion of. In this case, the maximum number of discrete cosine transform (DCT) coefficients generated is 64 for 8 × 8 and 16 for 4 × 4.

Thereafter, the selective encryption apparatus of H.264 / AVC multimedia content uses an integer discrete cosine transform (DCT) coefficient of an 8 × 8 or 4 × 4 macroblock set in the initialization step as an encryption key, and an integer discrete cosine stored in a temporary buffer. Encrypts the integer discrete cosine transform (DCT) coefficients stored in the temporary buffer by adding or subtracting the transform (DCT) coefficients and the encryption key (the arbitrary integer discrete cosine transform (DCT) coefficients set in the initialization step) (new integer discrete cosine transform (DCT) coefficients). (303).

Subsequently, the selective encryption apparatus of the H.264 / AVC multimedia content performs an arbitrary order according to the encryption key (the arbitrary integer discrete cosine transform (DCT) coefficient set in the initialization step). Substitute according to the stored in the buffer (304).

The apparatus for selective encryption of H.264 / AVC multimedia content quantizes the encrypted integer discrete cosine transform (DCT) coefficients (305) and quantizes the integer discrete cosine transform (DCT) according to the CABAC initialization table value generated earlier. Coefficients are entropy coded 306 to complete selective encryption of H.264 / AVC multimedia content.

4 is a flowchart illustrating a method of decoding H.264 / AVC multimedia content according to the present invention.

First, an apparatus for selectively decoding H.264 / AVC multimedia content is set by a user in an initialization step to decode an integer discrete cosine transform (DCT) coefficient of an image (H.264 / AVC multimedia content) in units of encoded macroblocks. Using an initial value, an integer matrix (an integer discrete cosine transform (DCT) coefficient) of 8x8 or 4x4 macroblocks is arbitrarily generated (401).

Subsequently, the apparatus for selectively decoding H.264 / AVC multimedia content calculates an integer discrete cosine transform (DCT) coefficient of an image (H.264 / AVC multimedia content) in units of macroblocks encoded according to an initially generated CABAC initialization table value. Entropy decode (402).

Subsequently, the selective decoding apparatus of the H.264 / AVC multimedia content dequantizes the entropy decoded integer discrete cosine transform (DCT) coefficient (403).

Subsequently, the apparatus for selectively decoding H.264 / AVC multimedia content uses an integer discrete cosine transform (DCT) coefficient of an 8 × 8 or 4 × 4 macroblock set in the initialization step as a decoding key and an integer discrete cosine stored in a temporary buffer. Decodes the integer discrete cosine transform (DCT) coefficients stored in the temporary buffer by adding or subtracting the transform (DCT) coefficients and the decryption key (the arbitrary integer discrete cosine transform (DCT) coefficients set in the initialization step) (new integer discrete cosine transform (DCT) coefficients). (404).

In addition, the apparatus for selectively decoding H.264 / AVC multimedia content randomly orders the code bits of the decoded integer discrete cosine transform (DCT) coefficients according to the decoding key (the arbitrary integer discrete cosine transform (DCT) coefficient set in the initialization step). Substitutions are stored in the buffer (405).

Next, the apparatus for selectively decoding H.264 / AVC multimedia content performs inverse discrete cosine transform (DCT) on the decoded integer discrete cosine transform (DCT) coefficients (406) to complete selective decoding of the H.264 / AVC multimedia content. do.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

As described above, the present invention selectively encrypts / decrypts H.264 / AVC multimedia content so that an unauthorized and anonymous user cannot play the H.264 / AVC multimedia content. By preventing the infringement of rights, the rights of copyright holders can be enhanced, and a rational digital content providing market can be formed.

In addition, the present invention, by providing a user with encrypted digital content of a variety of service methods, to meet the various needs of the author and / or copyright consumer, the user's convenience in using the encrypted digital content and the security of the content together There is an effect that can be promoted.

Claims (9)

A video encoding apparatus comprising integer discrete cosine transform means and quantization means, Random discrete cosine transform coefficient generating means for generating an arbitrary discrete cosine transform coefficient to encode an integer discrete cosine transform coefficient of the image converted by the integer discrete cosine transform means based on an initial value; Using the discrete discrete cosine transform coefficients generated by the arbitrary discrete cosine transform coefficient generating means as an encryption key, the integer discrete cosine transform coefficients of the image converted by the integer discrete cosine transform means and the encryption key are added or subtracted to the integer discrete. Encryption means for encrypting the integer discrete cosine transform coefficients of the image converted by the cosine transform means, and transferring the encrypted integer discrete cosine transform coefficients to the quantization means; CABAC table generating means for generating a CABAC initialization table for entropy coding; And Coding means for entropy coding the quantized value quantized by the quantization means using the CABAC initialization table value generated by the CABAC table generating means Image encoding apparatus comprising a. The method of claim 1, The CABAC table generating means, And generating a new CABAC initialization table value by adding a new pair of values generated using the encryption key to a coefficient pair of a CABAC initialization table. The method of claim 2, The arbitrary discrete cosine transform coefficient, And a discrete cosine transformed integer matrix of 8x8 or 4x4 macroblocks. A video decoding apparatus comprising inverse quantization means and inverse discrete cosine transform means, CABAC table generating means for generating a CABAC initialization table for entropy decoding of encrypted content (video); Decoding means for entropy decoding an integer discrete cosine transform coefficient of an encrypted image by using the CABAC initialization table value generated by the CABAC table generating means and transmitting the entropy decoding coefficient to the inverse quantization means; Arbitrary discrete cosine transform coefficient generating means for generating an arbitrary discrete cosine transform coefficient to decode the integer discrete cosine transform coefficient dequantized by the inverse quantization means based on an initial value; And By using the discrete discrete cosine transform coefficients generated by the arbitrary discrete cosine transform coefficient generating means as a decoding key, the integer discrete cosine transform coefficient dequantized by the inverse quantization means and the decoding key are added and subtracted by the inverse quantization means. Decoding means for decoding an inverse quantized integer discrete cosine transform coefficient and transferring the decoded integer discrete cosine transform coefficient to the inverse discrete cosine transform coefficient means Image decoding apparatus comprising a. The method of claim 4, wherein The arbitrary discrete cosine transform coefficient, And a discrete cosine transformed integer matrix of 8x8 or 4x4 macroblocks. In the H.264 / AVC based video encoding method, Generating a random discrete cosine transform coefficient to encode an integer discrete cosine transform coefficient of the image converted by the integer discrete cosine transform means based on the initial value; By using the discrete discrete cosine transform coefficient generated in the first step as an encryption key, the integer discrete cosine transform coefficient of the image converted by the integer discrete cosine transform means and the encryption key are added or subtracted by the integer discrete cosine transform means. Encrypting an integer discrete cosine transform coefficient of the transformed image and transferring the encrypted integer discrete cosine transform coefficient to the quantization means; Generating a context adaptive binary arithmetic coding (CABAC) initialization table required for entropy coding; And A fourth step of entropy coding an integer discrete cosine transform coefficient quantized by the quantization means using the CABAC initialization table value generated in the third step Image encoding method comprising a. The method of claim 6, The arbitrary discrete cosine transform coefficient, And a discrete cosine transformed integer matrix of 8x8 or 4x4 macroblocks. In the video decoding method based on H.264 / AVC, Generating a Context Adaptive Binary Arithmetic Coding (CABAC) initialization table for entropy decoding of encrypted content (video); A second step of entropy decoding an integer discrete cosine transform coefficient of an encrypted image by using the CABAC initialization table value generated in the first step and transferring it to inverse quantization means; Generating a random discrete cosine transform coefficient to decode an integer discrete cosine transform coefficient dequantized by the inverse quantization means based on an initial value; And The integer discrete cosine transform coefficient dequantized by the inverse quantization means and the decoded key are added or subtracted by the inverse quantization means using the discrete discrete cosine transform coefficient generated in the third step as a decoding key. A fourth step of decoding a cosine transform coefficient and transferring the decoded integer discrete cosine transform coefficient to inverse discrete cosine transform coefficient means Image decoding method comprising a. The method of claim 7, wherein The arbitrary discrete cosine transform coefficient, A discrete cosine transformed integer matrix of 8x8 or 4x4 macroblocks.

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