WO2011151982A1

WO2011151982A1 - Media encryption device, media encryption and decryption device, method of media encryption, and method of media encryption and decryption

Info

Publication number: WO2011151982A1
Application number: PCT/JP2011/002732
Authority: WO
Inventors: 大樹工藤; 優一出原; 勝大草野; 西川　博文
Original assignee: 三菱電機株式会社
Priority date: 2010-06-01
Filing date: 2011-05-17
Publication date: 2011-12-08
Also published as: JPWO2011151982A1; JP5393886B2

Abstract

In a media encryption device, a dynamic image compression unit (101) compresses video data and generates compressed video data which includes a header storing basic information of the video data and macroblock data storing the variable-length code of the video data. An encryption processing determination unit (102) identifies as encryption portions the leading portion of each header in the compressed video data and the portion extending from the tail end of a slice header to the head of the macroblock data, and an encryption processing unit (103) encrypts the identified portions while generating encrypted portion information indicative of the encrypted portions.

Description

Media encryption device, media encryption / decryption device, media encryption method, and media encryption / decryption method

The present invention relates to a media encryption device and a media encryption method for encrypting and protecting media data, and a media encryption / decryption device and a media encryption / decryption method for decrypting media data protected by encryption. is there.

Many multimedia contents are encrypted and protected for the purpose of copyright protection or browsing restrictions. Multimedia data such as images and sounds generally has a huge amount of data. When all data is encrypted, a huge amount of processing is required.

Therefore, Patent Documents 1 to 3 disclose methods for reducing the amount of data to be encrypted in a media file.
An apparatus for encrypting compressed moving image information according to Patent Document 1 encrypts only an intra-frame encoded image in moving image data compressed using intra-frame coding and inter-frame coding.

The image encryption device according to Patent Document 2 encrypts only the low frequency component of an image compressed by orthogonal transform and variable length coding.

The encoding device according to Patent Document 3 is notified of the changed variable-length code table by changing the variable-length code table to another table at an arbitrary time when compressing an image by variable-length encoding. It is impossible to read an image on the side of a decoding device that is not present.

Japanese Patent Laid-Open No. 7-184188 Japanese Patent Laid-Open No. 11-88857 JP 2001-274790 A

However, the invention according to Patent Document 1 has a problem that an image can be estimated by estimating an intra-frame encoded image.
In the invention according to Patent Document 2, since the start position of the variable length code can be easily specified, there is a problem that it is easily attacked. In addition, since a low frequency component generally has a large code amount, there is a problem that a large reduction in processing amount cannot be expected.
In the invention according to Patent Document 3, when there are few patterns in the variable-length code table, there is a problem that the brute force attack causes decoding.

The present invention has been made to solve the above-described problems. A media encryption apparatus and a media encryption device that perform highly secure encryption that can sufficiently withstand an attack while reducing the amount of processing required for encryption. And a media encryption / decryption device and media encryption / decryption method for encrypting / decrypting encrypted media data.

The media encryption apparatus according to the present invention is a compressed media data including a header area storing basic information of the media data and a variable length code area storing a variable length code of the media data, wherein the media data is compressed. Is input, at least a predetermined part of the header area and a part that extends from the end of the header area to the beginning of the variable-length code area as the part to be encrypted, and among the compressed media data, the cryptographic process And an encryption processing unit that encrypts the part specified by the determination unit.

The media encryption device according to the present invention is configured such that when compressed media data including compressed basic data including at least size information of the media data and a variable length code of the media data is input. The basic information and variable length code are multiplexed on the media file format to generate a compressed media file format including a basic information multiplexing area, a size information multiplexing area, and a variable length code multiplexing area, and at least the basic information multiplexing area An encrypted media file format creation unit is provided for encrypting a predetermined portion, a size information multiplexing region, and a portion extending from the end of the size information multiplexing region to the beginning of the variable length code multiplexing region.

The media encryption / decryption device according to the present invention is a compressed media data including a header area storing basic information of the media data and a variable length code area storing a variable length code of the media data, the media data being compressed. However, when encrypted compressed media data further encrypted is input, at least a predetermined part of the header area and a part straddling the beginning of the variable length code area from the end of the header area are decrypted to obtain the compressed media data. An encryption / decryption processing unit to be generated and a media decompression unit for decompressing the compressed media data are provided.

In the media encryption / decryption device according to the present invention, the compressed media data including the basic information including at least the size information of the media data and the variable length code of the media data obtained by compressing the media data further includes a predetermined media file. When an encrypted compressed media file format multiplexed and encrypted in the format is input, at least a predetermined part of the basic information multiplexed area, size information multiplexed area, and size information of the encrypted compressed media file format An encryption / decryption processing unit that generates a compressed media file format by encrypting and decrypting the portion extending from the end of the multiplexed region to the beginning of the variable-length code multiplexed region, and generating compressed media data by analyzing the compressed media file format Media file formats And analyzing unit is intended and a media decompression unit for decompressing the compressed media data for which the media file format analyzing unit has generated.

The media encryption method according to the present invention is a compressed media data comprising a header area storing basic information of the media data and a variable length code area storing a variable length code of the media data, wherein the media data is compressed. Is input, the encryption processing determination unit specifies at least a predetermined part of the header area and a part extending from the end of the header area to the beginning of the variable length code area as an encryption part, and an encryption process The encryption processing step for encrypting the portion specified in the encryption processing determination step in the compressed media data.

In the media encryption method according to the present invention, when compressed media data including compressed basic data including at least size information of the media data and a variable-length code of the media data is input. The media file format creation unit multiplexes basic information and variable length code into a predetermined media file format to generate a compressed media file format including a basic information multiplexed area, a size information multiplexed area, and a variable length code multiplexed area And an encryption media file format creation step for encrypting at least a predetermined part of the basic information multiplexing area, a size information multiplexing area, and a part extending from the end of the size information multiplexing area to the beginning of the variable length code multiplexing area. It is to be prepared.

The media encryption / decryption method according to the present invention is a compressed media data including a header area storing basic information of the media data and a variable length code area storing a variable length code of the media data, wherein the media data is compressed. However, when encrypted compressed media data that is further encrypted is input, the encryption / decryption processing unit decrypts at least a predetermined part of the header area and a part extending from the end of the header area to the beginning of the variable-length code area. Thus, the encryption / decryption processing step for generating the compressed media data and the media decompression unit include the media decompression step for decompressing the compressed media data.

In the media encryption / decryption method according to the present invention, the compressed media data including the basic information including at least the size information of the media data and the variable length code of the media data obtained by compressing the media data further includes a predetermined media file. When an encrypted compressed media file format multiplexed and encrypted in the format is input, the encryption / decryption processing unit performs at least a predetermined part of the basic information multiplexed area and size information in the encrypted compressed media file format. An encryption / decryption processing step for generating a compressed media file format by decrypting the multiplexed region and the portion extending from the end of the size information multiplexed region to the beginning of the variable-length code multiplexed region, and the media file format analyzing unit compresses Analyze media file format Te, a media file format analyzing step of generating a compressed media data, the media decompression unit is intended and a media expansion step of decompressing the compressed media data generated by the media file format analyzing step.

According to the present invention, the predetermined part of the header area and the part of the compressed media data that extends from the end of the header area to the beginning of the variable-length code area are encrypted. It is possible to obtain a media encryption apparatus and a media encryption method capable of generating highly-encrypted compressed and compressed media data that can sufficiently withstand an attack while being reduced.

According to the present invention, the predetermined part of the basic information multiplexing area, the size information multiplexing area, and the part extending from the end of the size information multiplexing area to the beginning of the variable length code multiplexing area in the compressed media file format are encrypted. Therefore, it is possible to obtain a media encryption apparatus and a media encryption method capable of generating a highly secure encrypted compressed media file format that can sufficiently withstand an attack while greatly reducing the processing required for encryption. Can do.

According to this invention, since the predetermined part of the header area and the part extending from the end of the header area to the beginning of the variable-length code area are decrypted in the encrypted compressed media data, the amount of encrypted data Therefore, it is possible to obtain a media encryption / decryption device and a media encryption / decryption method capable of sufficiently reducing the amount of processing at the time of encryption / decryption.

According to the present invention, the predetermined part of the basic information multiplexing area, the size information multiplexing area, the part extending from the end of the size information multiplexing area to the beginning of the variable length code multiplexing area in the encrypted compressed media file format, Since the encrypted data amount is small, a media encryption / decryption device and a media encryption / decryption method capable of sufficiently reducing the processing amount at the time of encryption / decryption can be obtained.

It is a block diagram which shows the structure of the media encryption apparatus concerning Embodiment 1 of this invention. It is a figure which shows an example of the relationship between a sequence and GOP. It is a figure which shows the example of the picture which consists of five slices. It is a figure which shows an example of the relationship between a macroblock and a block. It is a figure which shows the structural example of the compression moving image data which the moving image compression part shown in FIG. 1 outputs. 6 is a diagram illustrating an example of an encrypted part in compressed moving image data in the media encryption device according to Embodiment 1. FIG. It is a block diagram which shows the structure of the media encryption / decryption apparatus which concerns on Embodiment 1 of this invention. It is a figure which shows an example of the part encrypted in the compressed moving image data in the media encryption apparatus concerning Embodiment 2 of this invention. In the media encryption apparatus concerning Embodiment 3 of this invention, it is a figure which shows an example of the part encrypted in compressed moving image data. It is a figure which shows an example of the part encrypted in the compressed moving image data in the media encryption apparatus concerning Embodiment 4 of this invention. It is a block diagram which shows the structure of the media encryption apparatus based on Embodiment 5 of this invention. It is a block diagram which shows the structure of the media encryption apparatus based on Embodiment 6 of this invention. It is a figure which shows the box structure of MP4 file. It is a figure which shows an example of the data structure of MP4 file. H. 2 is a diagram illustrating an example of a structure of an MDAT box when H.264 moving image data is multiplexed. FIG. FIG. 25 is a diagram illustrating an example of a part to be encrypted in MP4 data in the media encryption device according to the sixth embodiment. It is a block diagram which shows the structure of the media encryption / decryption apparatus which concerns on Embodiment 6 of this invention. It is a figure which shows an example of the part encrypted in MP4 data in the media encryption apparatus concerning Embodiment 7 of this invention. It is a figure which shows an example of the part encrypted in MP4 data in the media encryption apparatus concerning Embodiment 8 of this invention. It is a block diagram which shows the structure of the media encryption apparatus based on Embodiment 9 of this invention.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings. Conventionally, compression of media data is sometimes referred to as encoding, and decompression of compressed media data is sometimes referred to as decoding. In the present invention, in order to distinguish between decoding and encryption / decryption, encoding of media data is performed. The expressions “compression” and “decoding” are used without using the expression “decoding”. Returning encrypted data to plaintext is called encryption / decryption.

Embodiment 1 FIG.
As shown in FIG. 1, the media encryption apparatus according to the first embodiment compresses non-compressed video data (media data) and includes compressed header data and variable-length code regions (compressed media data). ) Generating a moving image compression unit (media compression unit) 101, an encryption processing determination unit 102 for specifying a portion to be encrypted in the compressed moving image data based on determination information indicating the encrypted portion, and a compressed moving image The image processing unit 103 includes an encryption processing unit 103 that encrypts a part specified by the encryption processing determination unit 102 and generates encrypted compressed moving image data (encrypted compressed media data).

Hereinafter, each processing block will be described.
The moving image compression unit 101 performs compression processing on uncompressed moving image data, and sequentially outputs compressed moving image data. This compression processing is based on MPEG (Moving Picture Expert Group) or H.264. Any method such as H.264 or the like that performs variable-length coding may be used.

Here, a basic data configuration of the moving image compression method handled by the moving image compression unit 101 will be described. First, an entire moving image is called a sequence. The sequence is composed of a plurality of images, and a plurality of images of a part of the sequence are referred to as GOP (Group Of Pictures). FIG. 2 is a diagram showing a relationship between a sequence and a GOP, and shows an example composed of a sequence composed of 20 images and four GOPs composed of 5 images.

Also, one image is called a picture. Furthermore, a part of the picture is called a slice, and the picture is composed of one or more slices. This slice is composed of one or more macroblocks. FIG. 3 is a diagram illustrating an example of a picture including five slices.

Also, the macro block is composed of 16 pixels × 16 lines, and is further divided into blocks of 8 pixels × 8 lines. FIG. 4 is a diagram illustrating an example of the relationship between macroblocks and blocks.

FIG. 5 is a diagram illustrating a configuration example of the compressed moving image data output from the moving image compression unit 101. The compressed moving image data includes a sequence header, a GOP header, and GOP data. The GOP data includes a picture header and picture data. The picture data includes a slice header and macroblock data.

Among the compressed video data, the sequence header, GOP header, picture header, and slice header are each referred to as a header area. Each header area contains basic information necessary for moving image compression processing, such as image width, height, bit depth, frame rate, picture type (intra-picture coded picture, inter-picture coded picture), and quantization parameter. To be recorded. Also, a unique word called a start code is often recorded at the beginning of each header area. As a result, random access to the moving image becomes possible, and even if a part of the data of the moving image is damaged, it can be expanded from the start code point.

Among the compressed video data, the macro block data is referred to as a variable length code area. Actually compressed moving image data is recorded in this macro block portion, and the data is generally variable-length encoded. As this variable-length encoding method, various methods such as Huffman coding and arithmetic coding are adopted for each moving image compression format, but the moving image compression unit 101 does not ask any kind.

Note that although a general moving image compression method has been described as an example here, terms such as picture, GOP, slice, macroblock, and block may differ depending on the moving image compression method. In addition, depending on the moving image compression method, there is a method in which no GOP header or picture header exists. 4 shows 16 pixels × 16 lines as an example of a macro block and 8 pixels × 8 lines as an example of a block. However, the size differs depending on the image compression method, and is therefore limited to the example of FIG. is not. For example, H.M. In the H.264 system, the block size is 4 pixels × 4 lines. Here, it is assumed that there is no difference in the configuration and terminology of each region included in the compressed moving image data generated by the moving image compression unit 101.

Compressed moving image data (shown in FIG. 5) sequentially output from the moving image compression unit 101 is input to the encryption processing determination unit 102 and the encryption processing unit 103, respectively.

The encryption processing determination unit 102 performs encryption processing determination on sequentially input compressed moving image data based on predetermined determination information, and determines whether or not the compressed moving image data corresponds to an encrypted portion. The determination result is output to the encryption processing unit 103. Hereinafter, an example of an encrypted part defined as determination information will be described.

FIG. 6 is a diagram showing a portion to be encrypted in the compressed moving image data. In the example of FIG. 6, the encrypted part in the middle of the GOP data indicates the encrypted part at the head of the picture header and the encrypted part of the picture data. Further, the encrypted part in the middle of the picture data indicates an encrypted part at the head of the slice header and an encrypted part extending from the end of the slice header to the head of the macroblock data. Therefore, the encrypted part is only the head part of each sequence, GOP, picture, and slice header area, and the part extending from the end of the slice header (header area) to the head of the macroblock data (variable length code area). .

As described above, a start code serving as a return position for random access and moving image playback is recorded as a unique word at the top of the header area. Therefore, by encrypting the head part of the header area, it becomes difficult to specify the position of the start code that is the start position of the header, and the width, height, bit depth, and frame rate of the image recorded in the header area are difficult. It is difficult to obtain basic information regarding compression of moving images such as picture type and quantization parameter. This makes it difficult to encrypt / decrypt encrypted compressed video data and decompress compressed video data on the media encryption / decryption device side.

Also, it is optional for the part to be encrypted from the beginning of the header area. As the amount of encryption increases, encryption / decryption and expansion on the media encryption / decryption device side become more difficult, while the amount of processing required for encryption in the encryption processing unit 103 described later increases. Therefore, it is preferable to determine the encrypted portion so as to include important portions of the moving image data such as the width, height, bit depth, frame rate, picture type, quantization parameter, and the like of the image.

Also, with respect to a portion extending from the end of the slice header to the beginning of the macroblock data, which is another encrypted portion, the encrypted portion is determined so as to always include the start position of the variable length code. As described above, since the macroblock data is image data compressed by the variable length encoding process of the moving image compression unit 101, the media encryption / decryption device side encrypts the start position of the variable length code area. Variable length decoding becomes difficult, and moving image reproduction becomes difficult.

The encryption processing unit 103 receives the determination result output from the encryption processing determination unit 102 and executes encryption of the compressed moving image data output from the moving image compression unit 101 using an encryption key input separately. Then, encrypted compressed moving image data and encrypted partial information are generated and output.

As shown in FIG. 6, the encrypted compressed video data includes a head portion of each header area as shown in FIG. 6 and a portion extending from the end of the slice header to the head of the variable-length code area in each header area. Is encrypted. Compared to the case where the entire sequence is encrypted, the amount of processing required for the encryption process can be greatly reduced.
The encrypted portion information is information indicating which portion is encrypted in the encrypted compressed moving image data, that is, the position of the encrypted portion, and is used when performing decryption. The encrypted partial information is required to be managed in the same manner as the encryption key, but the management method is not limited in the present invention.

It should be noted that there are many known encryption methods such as DES (Data Encryption Standard) and AES (Advanced Encryption Standard), but the encryption method used by the encryption processing unit 103 is not limited.

Next, a media encryption / decryption device that performs encryption / decryption of encrypted compressed video data will be described.
As shown in FIG. 7, the media encryption / decryption device according to Embodiment 1 uses the encrypted compressed moving image data (encrypted compressed media data) output from the above-described media encryption device as an input, A decryption processing unit 104 that encrypts and decrypts the encrypted portion of the encrypted compressed video data to generate plain compressed video data (compressed media data), and decompresses the compressed video data to generate an uncompressed video A moving image expansion unit (media expansion unit) 105 that generates data is included.

Hereinafter, each processing block will be described.
When the encrypted portion information and the encrypted compressed moving image data are input, the encryption / decryption processing unit 104 specifies the encrypted portion shown in FIG. 6 of the encrypted compressed moving image data from the encrypted portion information and separately inputs it. Using the encrypted key, the encrypted portion is encrypted and decrypted to obtain compressed moving image data in plain text. The obtained compressed moving image data is output to the moving image decompression unit 105.

The encryption / decryption processing unit 104 encrypts and decrypts the head part of each header area and the part of each header area that extends from the end of the slice header to the head of the variable-length code area in the encrypted compressed video data. Therefore, compared with the case where the entire sequence is encrypted / decrypted, the portion for performing the encryption / decryption process is small, and the encryption / decryption can be performed with a small processing amount.

The moving image decompression unit 105 performs decompression processing of the compressed moving image data input from the encryption / decryption processing unit 104 by a moving image decompression method corresponding to the moving image compression method by the encryption processing unit 103 of the media encryption device. Obtain compressed video data.
Thereby, the media encryption / decryption device can obtain an uncompressed moving image.

As described above, according to the first embodiment, the media encryption apparatus compresses moving image data and stores a header storing basic information of the moving image data and a variable length code of the moving image data. A moving image compression unit 101 that generates compressed moving image data including data, and when compressed moving image data is input from the moving image compression unit 101, macroblock data from the beginning of each header and the end of each slice header Encryption processing determination unit 102 that identifies a portion that straddles the beginning of the encrypted data as a portion to be encrypted, and a portion of the compressed moving image data that is encrypted by the encryption processing determination unit 102 and that indicates the encrypted portion And an encryption processing unit 103 that generates the encrypted partial information. For this reason, it is possible to encrypt compressed moving image data with high security that can sufficiently withstand an attack while greatly reducing the processing required for encryption.

Further, according to the first embodiment, when the encrypted part information indicating the encrypted part of the encrypted compressed moving image data is input to the media encryption / decryption device together with the encrypted compressed moving image data, An encryption / decryption processing unit 104 that encrypts / decodes a head portion of each header indicated by the segmented portion information and a portion extending from the end of each slice header to the head of the macroblock data, and compressed moving image data; And a moving image expansion unit 105 that expands the image. For this reason, encryption / decryption can be performed with a small processing amount when performing encryption / decryption.

Embodiment 2. FIG.
Since the media encryption apparatus according to the second embodiment has the same configuration as that of the media encryption apparatus according to the first embodiment shown in FIG. 1, the following description will be given with reference to FIG. In the first embodiment, as shown in FIG. 6, the head portion of each header in the compressed moving image data and the portion straddling the head of the macroblock data including the variable length code start position from the end of the slice header. Encrypted. On the other hand, in the second embodiment, as shown in FIG. 8, a portion straddling the head immediately before each header and a portion straddling the head of macroblock data including the variable length code start position from the end of the slice header And encrypt.

Therefore, the encryption processing determination unit 102 determines the encrypted part of the compressed moving image data sequentially input from the moving image compression unit 101 according to the determination information in which the encrypted part shown in FIG. Performs encryption processing of the encrypted portion according to the determination result.

By encrypting the header area immediately before each header area, it becomes more difficult to determine the start code position of each header area, and the amount of processing required for encryption increases as compared with the first embodiment. , Can increase safety.

The media encryption / decryption device according to the second embodiment has the same configuration as that of the media encryption / decryption device according to the first embodiment shown in FIG. 7, and the encrypted compression encrypted by the above-described media encryption device. Using the moving image data and the encrypted partial information, encryption / decryption is performed by the same operation as the media encryption / decryption device of the first embodiment.

As described above, according to the second embodiment, the encryption processing determination unit 102 of the media encryption device performs the macroblock data from the portion of the compressed video data that straddles the head immediately before each header and the end of each slice header. The portion straddling the head of the URL is specified as the portion to be encrypted. For this reason, it becomes more difficult to determine the start code position of the header area, and safety can be further improved.

Embodiment 3 FIG.
Since the media encryption apparatus according to the third embodiment has the same configuration as that of the media encryption apparatus according to the first embodiment shown in FIG. 1, the following description will be given with reference to FIG. In the first embodiment, as shown in FIG. 6, the head portion of each header in the compressed moving image data, and the portion straddling the head of the macroblock data including the variable length code start position from the end of each slice header, Was encrypted. On the other hand, in the third embodiment, as shown in FIG. 9, the entire header and the portion straddling the beginning of the macroblock data including the variable length code start position from the end of each slice header are encrypted. .

Therefore, the encryption processing determination unit 102 determines the encrypted part of the compressed moving image data sequentially input from the moving image compression unit 101 according to the determination information in which the encrypted part shown in FIG. 9 is defined, and the encryption processing unit 103 Performs encryption processing of the encrypted portion according to the determination result.

Encrypting the entire information in each header area increases the amount of processing required for encryption as compared with the first embodiment, but can further enhance safety.

Of the header areas, all important header areas that affect all sequences such as sequence headers are encrypted, and header areas that only affect slices such as slice headers are the same as in the first and second embodiments. Only a part of the header area (the head part, or the head part and the part immediately before) may be encrypted.

The media encryption / decryption device according to Embodiment 3 has the same configuration as the media encryption / decryption device of Embodiment 1 shown in FIG. 7, and the encrypted compression encrypted by the above-described media encryption device. Using the moving image data and the encrypted partial information, encryption / decryption is performed by the same operation as the media encryption / decryption device of the first embodiment.

As described above, according to the third embodiment, the encryption processing determination unit 102 of the media encryption device performs each header of the compressed moving image data and a portion extending from the end of each slice header to the beginning of the macroblock data. It was configured to be specified as the part to be encrypted. For this reason, safety can be further improved.

Embodiment 4 FIG.
Since the media encryption apparatus according to the fourth embodiment has the same configuration as that of the media encryption apparatus according to the first embodiment shown in FIG. 1, the following description will be given with reference to FIG. In the first embodiment, as shown in FIG. 6, the head portion of each header in the compressed moving image data and the portion straddling the head of the macroblock data including the variable length code start position from the end of the slice header. Encrypted. In contrast, in the fourth embodiment, as shown in FIG. 10, in addition to the head portion of each header and the portion straddling the head of macroblock data including the variable length code start position from the end of the slice header, Furthermore, any part other than the beginning of the macroblock data is also encrypted.

Any part other than the beginning of the macro block data may be selected completely at random, or a part including specific data such as a macro block type may be preferentially selected, or the macro block data The first half may be selected preferentially. As a result, when image decompression processing is performed on the encrypted stream without performing decryption on the decryption device side, variable length decryption fails in the first half of the image and image decompression processing is performed at an early stage. Will be interrupted, so safety can be improved.

Also, in order to increase the security, the encrypted portion of the macroblock data of the intra-picture coded picture may be increased.

In many image compression methods, DCT (Discrete Cosine Transform) conversion processing and motion compensation prediction processing using motion vectors are used. Therefore, in the case where the moving image compression unit 101 is configured to perform DCT conversion processing and motion compensation prediction processing, in order to improve safety, the low-frequency component of the DCT coefficient that characterizes the image for the macroblock data of the intra-picture coded picture. The encrypted portion may be changed depending on the picture type, such as encrypting the portion and encrypting the motion vector portion of the macroblock data of the inter-picture coded picture.

By encrypting an arbitrary part other than the head of the macroblock data and increasing the encrypted part of each macroblock data, the processing amount required for the encryption is increased as compared with the first embodiment, but the safety is further improved. be able to.

In addition, although the head part of each header area is encrypted as in the first embodiment, the present invention is not limited to this, and a part that straddles the head immediately before each header area as in the second embodiment. May be encrypted, or the entire header area may be encrypted as in the third embodiment.

The media encryption / decryption device according to the fourth embodiment has the same configuration as that of the media encryption / decryption device of the first embodiment shown in FIG. 7, and the encrypted compression encrypted by the above-described media encryption device. Using the moving image data and the encrypted partial information, encryption / decryption is performed by the same operation as the media encryption / decryption device of the first embodiment.

As described above, according to the fourth embodiment, the encryption processing determination unit 102 of the media encryption apparatus further specifies an arbitrary part other than the beginning of the macroblock data in the compressed moving image data as a part to be encrypted. Configured. For this reason, safety can be further improved.

Embodiment 5 FIG.
FIG. 11 is a block diagram showing a configuration of the media encryption apparatus according to the fifth embodiment. The media encryption device shown in FIG. 11 includes an encryption processing determination unit 102 and an encryption processing unit 103. 11 that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

In the media encryption devices according to the first to fourth embodiments, as shown in FIG. 1, while the moving image compression unit 101 compresses uncompressed moving image data, the encryption processing determination unit 102 sequentially specifies the encrypted portions. Thus, the encryption processing unit 103 performs encryption to obtain encrypted compressed moving image data and encrypted partial information. On the other hand, the media encryption apparatus according to the fifth embodiment omits the moving image compression unit 101 as shown in FIG. 11, and uses compressed moving image data that has already been subjected to compression processing as an input for encryption. The process determining unit 102 identifies the encrypted part, and the encryption process unit 103 performs encryption to obtain encrypted compressed moving image data and encrypted part information.

As described above, according to the fifth embodiment, the media encryption apparatus is a macro in which moving image data is compressed, a header storing basic information of the moving image data, and a variable length code of the moving image data are stored. When compressed moving image data including block data is input, an encryption processing determination unit 102 that identifies a predetermined portion of each of the header and macroblock data as an encrypted portion, and among the compressed moving image data, an encryption processing determination unit An encryption processing unit 103 that encrypts the part identified by 102 is configured. Therefore, encrypted compressed moving image data can be generated from the compressed moving image data that has already been subjected to compression processing.

When the media encryption apparatus according to Embodiments 1 to 5 is configured by a computer, media encryption describing the processing contents of the moving image compression unit 101, the encryption processing determination unit 102, the encryption processing unit 103, etc. The program may be stored in the memory of the computer, and the CPU of the computer may execute the media encryption program stored in the memory.
Similarly, when the media encryption / decryption devices according to Embodiments 1 to 5 are configured by a computer, a media encryption / decryption program describing the processing contents of the encryption / decryption processing unit 104, the moving image decompression unit 105, and the like is stored in the computer. The media encryption / decryption program stored in the memory may be executed by the CPU of the computer.

Embodiment 6 FIG.
In the sixth embodiment, a media encryption device and a media encryption / decryption device configured to encrypt and decrypt video data multiplexed in a media file format will be described. In the following description, an MPEG-4 media file format (hereinafter referred to as MP4) among various media file formats capable of multiplexing compressed moving image data will be described as an example. As a moving image compression method, H.264 is used. The H.264 system is used.

FIG. 12 is a block diagram showing the configuration of the media encryption device according to the sixth embodiment. The media encryption device shown in FIG. H.264 format compressed moving image data (compressed media data, hereinafter referred to as H.264 moving image data), a moving image compressing unit (media compressing unit) 106; An H.264 moving image data is composed of an encrypted MP4 generation unit (encrypted media file format creation unit) 107 that generates encrypted MP4 data (encrypted compressed media file format) by multiplexing and encrypting the moving image data on MP4.

Hereinafter, each processing block will be described.
The moving image compression unit 106 converts the uncompressed moving image data to H.264. H.264 format for compression. H.264 moving image data is output. H.264 moving image analysis data is output. This H. H.264 moving image analysis data is size information indicating the size of each picture, and is data necessary for generating MP4 data in the subsequent stage.

Encrypted MP4 generation unit 107 is an H.264 that is sequentially input from moving image compression unit 106. H.264 video data and H.264 video data. The encrypted MP4 data and the MP4 encrypted partial information are generated using the H.264 moving image analysis data and the encryption key input separately.

Here, the structure of the MP4 file will be described.
An MP4 file has a data structure called a box. FIG. 13 shows the structure of the MP4 file box. As shown in FIG. 13, the box structure includes a box length (4 bytes), a box name (4 bytes), and data (data size specified by the box length—8 bytes). The format and contents of the data part of the box are determined by the box name. Boxes may also be nested.

FIG. 14 is a diagram showing an example of the data structure of the MP4 file. FIG. 14 shows the simplest file structure of the media file format of the MPEG-4 format. This MP4 file is composed of an FTYP (file type) box, a MOOV (movie) box, and an MDAT (media data) box. However, the MOOV box has a tree structure in which a plurality of boxes are nested inside, as will be described later.

Basic information of media data (moving image data) is recorded in the MOOV box. For example, video length, width, height, audio sampling frequency, and the like. In addition, what kind of media data is multiplexed in what size (size) in the MP4 file is recorded.
This MOOV box constitutes a basic information multiplexing area.

Next, boxes nested within the MOOV box are described and how the above information is recorded.
Within the MOOV box, there is a box called STSZ (or STZ2, which may be replaced with STZ2 when STSZ is described below). In the STSZ box, the size of the sample is recorded. Here, the sample size is the size of each frame if the media data is video, and the size of the data in a determined time unit if the media data is audio. Therefore, the size of each media data in the MP4 file can be known from the contents of the STSZ box.

In addition, a box called STCO (or CO64, which may be replaced with CO64 when STCO is described below) exists in the MOOV box. In this STCO box, the position of the chunk in the MP4 file is recorded. A chunk is a group of one or more samples. If media data is video, it is a group of one or more video frames. If media data is audio, one or more predetermined time units are used. This is a summary of the data.

Furthermore, there is a box called STSC in the MOOV box. In this STSC box, the number of samples in the chunk is recorded. Therefore, the position and size of each sample can be obtained from the contents of the STSZ box, STCO box, and STSC box.

The MDAT box is a box in which actual media data such as video or audio is multiplexed. In particular, H.C. FIG. 15 shows the structure of the MDAT box when H.264 moving image data is multiplexed. The picture data shown in FIG. This is data of each picture of compressed moving image data compressed by the H.264 system. The size is the size of data of each picture. That is, the structure is such that the size of each picture data can be easily understood.
The size of the MDAT box constitutes a size information multiplexing area, and the picture data constitutes a variable length code multiplexing area.

When the encrypted MP4 generation unit 107 generates the MP4 file structure data (compressed media file format) as described above, the H.P. H.264 moving image analysis data is used to generate STSZ, STCO, and STSC boxes and to determine the size of data for each picture in the MDAT box.

In addition, the encrypted MP4 generation unit 107 generates encrypted MP4 data by encrypting a part of the MOOV box and a part of the MDAT box among the data having the MP4 file structure as described above.
The portions to be encrypted in the MOOV box (arbitrary portions of the basic information multiplexing area) are the STSZ, STCO, and STSC boxes. As a result, H.C. It is possible to make it difficult to specify the position and size of H.264 moving image data. However, when there is a margin in the encryption processing capacity of the encrypted MP4 generation unit 107 or when it is desired to further increase the security, the other part of the MOOV box may be encrypted.

FIG. 16 is a diagram showing an example of an encrypted part in MP4 data. As shown in FIG. 16, the portion to be encrypted in the MDAT box includes the entire size (size information multiplexing area) in the MDAT box and the beginning of the picture data (variable length code multiplexing area) from the end of the size. The straddle part. At this time, the picture data includes the start position of the variable length code. By encrypting the portion of the picture data including the start position of the variable length code including the variable length code start position from the size, it is difficult to specify the size of the picture, making variable length decoding difficult, and improving the safety.

As described above, the encrypted MP4 generation unit 107 generates and outputs encrypted MP4 data obtained by encrypting the part illustrated in FIG. 16 and MP4 encrypted part information indicating the encrypted part of the encrypted MP4 data.

Next, a media encryption / decryption device that performs encryption / decryption of encrypted MP4 data will be described.
FIG. 17 is a block diagram showing the configuration of the media encryption / decryption device according to the sixth embodiment. The media encryption / decryption device shown in FIG. 17 uses the encrypted MP4 data (encrypted compressed media file format) output from the above-described media encryption device as an input, and uses the encrypted portion in the encrypted MP4 data. An encrypted MP4 encryption / decryption unit (encryption / decryption processing unit) 108 that generates plaintext MP4 data (compressed media file format) by decryption and H.264 MP4 analysis unit (media file format analysis unit) 109 that generates H.264 moving image data (compressed media data); A moving image expansion unit (media expansion unit) 110 that expands H.264 moving image data to generate uncompressed moving image data.

Hereinafter, each processing block will be described.
When the MP4 encrypted part information and the encrypted MP4 data are input, the encrypted MP4 encryption / decryption unit 108 specifies the encrypted part shown in FIG. 16 of the encrypted MP4 data from the MP4 encrypted part information and inputs it separately. The encrypted part is encrypted and decrypted using the encryption key to obtain MP4 data in plain text. The obtained MP4 data is output to the MP4 analysis unit 109.

The MP4 analysis unit 109 includes, among the encrypted MP4 data, STSZ, STCO, and STSC boxes that are a part of the MOOV box, a size that is a part of the MDAT box, and a part that extends from the end of the size to the top of the picture data. Therefore, encryption / decryption is possible with a small amount of processing.

MP4 analysis unit 109 analyzes the MP4 data, H.264 moving image data is extracted and output to the moving image decompression unit 110.

The moving image decompression unit 110 is H.264. H.264 moving image data is decompressed to obtain uncompressed moving image data.

As described above, according to the sixth embodiment, the media encryption apparatus compresses the moving image data, and the H.03 which is the size information of the moving image data. H.264 moving image analysis data and a variable length code of the moving image data. H.264 moving image data is generated from the moving image compression unit 106. H.264 moving image data is input, Based on H.264 moving image analysis data. H.264 moving picture data basic information is determined, MP4 data including MOOV box and MDAT box is generated by multiplexing basic information, size information and variable length code on MP4, and STSZ, STCO, which are part of MOOV box, and An STSC box, a size that is a part of the MDAT box, and an encrypted MP4 generation unit 107 that encrypts a portion that extends from the end of the size to the beginning of the picture data are configured. Therefore, it is possible to encrypt MP4 data with high security that can sufficiently withstand an attack while greatly reducing the processing required for encryption.

Further, according to the sixth embodiment, when MP4 encrypted portion information indicating an encrypted portion of the encrypted MP4 data is input together with the encrypted MP4 data, the media encryption / decryption device receives the MP4 encrypted portion. MP4 data is generated by decrypting the STSZ, STCO, and STSC boxes that are part of the MOOV box indicated by the information, the size that is part of the MDAT box, and the part that extends from the end of the size to the beginning of the picture data. The encrypted MP4 encryption / decryption unit 108 analyzes the MP4 data, MP4 analysis unit 109 that generates H.264 moving image data; And a moving image expansion unit 110 that expands H.264 moving image data. For this reason, encryption / decryption can be performed with a small processing amount when performing encryption / decryption.

Embodiment 7 FIG.
Since the media encryption apparatus according to the seventh embodiment has the same configuration as that of the media encryption apparatus according to the sixth embodiment shown in FIG. 12, the following description will be given with reference to FIG. In the sixth embodiment, a part of the MOOV box in the MP4 data, the STSZ, STCO, and STSC boxes, the size in the MDAT box, and the part straddling the beginning of the picture data including the variable length code start position from the end of the size, Was encrypted. On the other hand, the encrypted MP4 generation unit 107 of the seventh embodiment includes a part of the STOV, STCO and STSC boxes of the MOOV box in the MP4 data, and the size in the MDAT box as shown in FIG. In addition to the portion extending from the end of the size to the beginning of the picture data including the variable length code start position, the portion immediately preceding the size of the MDAT box (the portion immediately preceding the size information multiplexing area) is also encrypted.

Encrypting the immediately preceding portion of the size increases the amount of processing required for encryption as compared with the sixth embodiment, but it becomes difficult to specify the position of the size of each picture data and the size itself, thereby improving safety. be able to.

The media encryption / decryption device according to the seventh embodiment has the same configuration as that of the media encryption / decryption device according to the sixth embodiment shown in FIG. 17, and the encrypted MP4 encrypted by the above-described media encryption device. Using the data and the MP4 encrypted partial information, encryption / decryption is performed by the same operation as the media encryption / decryption apparatus of the sixth embodiment.

As described above, according to the seventh embodiment, the encrypted MP4 generation unit 107 of the media encryption apparatus sets the STSZ, STCO, and STSC boxes that are part of the MOOV box in the MP4 data and the size immediately before the size in the MDAT box. The portion, the size, and the portion extending from the end of the size to the beginning of the picture data are encrypted. For this reason, it becomes difficult to specify the position of the size of each picture data and the size itself, and the safety can be further improved.

Embodiment 8 FIG.
Since the media encryption device according to the eighth embodiment has the same configuration as that of the media encryption device according to the sixth embodiment shown in FIG. 12, the following description will be given with reference to FIG. In the sixth embodiment, the STSZ, STCO, and STSC boxes that are part of the MOOV box in the MP4 data, the size in the MDAT box, and the part that straddles the beginning of the picture data including the variable length code start position are encrypted. . On the other hand, the encrypted MP4 generation unit 107 of the eighth embodiment includes a part of the STOV, STCO and STSC boxes of the MOOV box in the MP4 data, and the size in the MDAT box as shown in FIG. In addition to the portion extending from the end of the size to the beginning of the picture data including the variable length code start position, there is also an arbitrary portion other than the beginning of the MDAT box picture data (an arbitrary portion other than the beginning of the variable length code multiplexing area) Encrypt.

Arbitrary portions other than the head of picture data in the MDAT box may be selected completely randomly, or a portion including specific data such as a macroblock type may be preferentially selected, or picture data The first half of the may be preferentially selected. As a result, when image decompression processing is performed on the encrypted stream without performing decryption on the decryption device side, variable length decryption fails in the first half of the image and image decompression processing is performed at an early stage. Will be interrupted, so safety can be improved.

Also, in order to increase safety, the encrypted portion of the macroblock data included in the picture data of the intra-picture encoded picture may be increased.

In addition, the H.D. In the H.264 video compression method, 4 pixel × 4 line integer precision conversion processing and motion compensation prediction processing using motion vectors are used. Therefore, in order to increase safety, the macroblock data included in the intra-picture coded picture data is encrypted with respect to the macro-block data included in the inter-picture coded picture data. For data, the encrypted portion may be changed depending on the picture type, such as encrypting the motion vector portion.

By encrypting an arbitrary part other than the head of the picture data in the MDAT box and increasing the encrypted part of each picture data, the processing amount required for the encryption is increased as compared with the sixth embodiment, but the safety is further improved. Can be increased.

Note that the end portion of the picture data corresponding to the straight portion of the size of the MDAT box may be encrypted as in the seventh embodiment.

The media encryption / decryption device according to the eighth embodiment has the same configuration as that of the media encryption / decryption device according to the sixth embodiment shown in FIG. 17, and the encrypted MP4 encrypted by the above-described media encryption device. Using the data and the MP4 encrypted partial information, encryption / decryption is performed by the same operation as the media encryption / decryption apparatus of the sixth embodiment.

As described above, according to the eighth embodiment, the encrypted MP4 generation unit 107 of the media encryption apparatus performs the STSZ, STCO, and STSC boxes as part of the MOOV box in the MP4 data, the size in the MDAT box, A portion extending from the end of the size to the top of the picture data and an arbitrary portion other than the top of the picture data are encrypted. For this reason, safety can be further improved.

Embodiment 9 FIG.
FIG. 20 is a block diagram showing a configuration of the media encryption apparatus according to the ninth embodiment. The media encryption device shown in FIG. H.264 moving image data is analyzed, and the size information of each picture is H.264. A moving image analysis unit 111 that outputs H.264 moving image analysis data and an encrypted MP4 generation unit 107 are configured. The encrypted MP4 generation unit 107 is the same as the encrypted MP4 generation unit 107 of the sixth embodiment shown in FIG.

In the media encryption apparatuses according to the above sixth to eighth embodiments, as shown in FIG. 12, the moving image compression unit 106 converts the uncompressed moving image data to H.264. H.264 moving image data and H.264 The H.264 moving image analysis data is generated, and the encrypted MP4 generation unit 107 performs multiplexing and encryption to obtain encrypted MP4 data. In contrast, the media encryption device according to the ninth embodiment includes a moving image analysis unit 111 instead of the moving image compression unit 106 as shown in FIG. The moving image analysis unit 111 uses the H.264 moving image data. H.264 moving image analysis data is generated. H.264 moving image data and the obtained H.264. H.264 moving image analysis data is used for multiplexing and encryption to output encrypted MP4 data and MP4 encrypted partial information.

As described above, according to the ninth embodiment, the media encryption apparatus is provided with an H.264 including a variable length code of the moving image data, which is the compressed moving image data. H.264 moving image data is input, H.264 moving image data is analyzed, and the size information of moving image data is H.264. H.264 moving image analysis data is generated. Based on H.264 moving image analysis data. H.264 Basic information of moving image data is determined, MP4 data including MOOV box and MDAT box is generated by multiplexing basic information, size information and variable length code on MP4, and predetermined parts of MOOV box and MDAT box are encrypted And an encrypted MP4 generation unit 107 to be configured. For this reason, H. already compressed has been performed. Encrypted MP4 data can be generated from H.264 video data.

In the case where the media encryption apparatus according to Embodiments 6 to 9 is configured by a computer, media describing processing contents such as the moving image compression unit 106, the encrypted MP4 generation unit 107, the moving image analysis unit 111, and the like. The encryption program may be stored in a computer memory, and the computer CPU may execute the media encryption program stored in the memory.
Similarly, when the media encryption / decryption devices according to Embodiments 6 to 9 are configured by a computer, the processing contents of the encrypted MP4 encryption / decryption unit 108, the MP4 analysis unit 109, the moving image decompression unit 110, and the like are described. The media encryption / decryption program may be stored in the memory of the computer, and the CPU of the computer may execute the media encryption / decryption program stored in the memory.

In the first to ninth embodiments, moving image data is used as an example of media data to be encrypted. However, the type of data is not limited to this, and a header area and a variable-length code area are used. Or media data such as audio data and still image data including a basic information multiplexing area, a size information multiplexing area, and a variable length code multiplexing area. Even in such media data, basic information necessary for reproduction included in the header area or the basic information multiplexing area (such as the number of channels, sampling frequency and bit depth for audio data, image width for still image data, By encrypting the height, bit depth, quantization parameter, etc.) and the part that spans the variable length code start position from the header area or the size information multiplexing area, the processing required for encryption is greatly reduced, and safety is ensured. Highly encrypted media data can be generated.

As described above, the media encryption device, the media encryption / decryption device, the media encryption method, and the media encryption / decryption method according to the present invention have a sufficiently small processing amount at the time of encryption / decryption because the amount of encrypted data is small. Media encryption / decryption device and media encryption / decryption method that can be performed, media encryption device and media encryption method for encrypting and protecting media data, and media data protected by encryption Is suitable for use in a media encryption / decryption device, a media encryption / decryption method, and the like.

101, 106 Moving image compression unit, 102 Encryption processing determination unit, 103 Encryption processing unit, 104 Encryption / decryption processing unit, 105 Moving image decompression unit, 107 Encrypted MP4 generation unit, 108 Encrypted MP4 encryption / decryption unit, 109 MP4 analysis unit 110, moving image expansion unit, 111 moving image analysis unit.

Claims

When compressed media data including a header area storing basic information of the media data and a variable length code area storing a variable length code of the media data is input, the header area is at least the header area. An encryption processing determination unit that identifies the predetermined part and the part that extends from the end of the header area to the beginning of the variable-length code area as an encrypted part;
A media encryption apparatus comprising: an encryption processing unit that encrypts a portion specified by the encryption processing determination unit in the compressed media data.
The encryption processing determination unit is characterized in that the beginning part of each header area in the compressed media data and the part extending from the end of each header area to the beginning of the variable-length code area are specified as parts to be encrypted. The media encryption device according to claim 1.
The encryption processing determination unit specifies a portion of the compressed media data that extends from immediately before the header area and a portion that extends from the end of each header area to the beginning of the variable-length code area as an encrypted portion. The media encryption device according to claim 1.
The encryption processing determination unit identifies each header area in the compressed media data and a part extending from the end of each header area to the beginning of the variable-length code area as an encrypted part. The described media encryption device.
2. The media encryption apparatus according to claim 1, wherein the encryption processing determination unit further specifies an arbitrary portion other than the beginning of the variable length code area in the compressed media data as the portion to be encrypted.
A media compression unit that compresses media data and generates compressed media data including a header area that stores basic information of the media data and a variable-length code area that stores a variable-length code of the media data. The media encryption device according to claim 1.
The media encryption apparatus according to claim 1, wherein the encryption processing unit generates encrypted part information indicating the encrypted part.
When compressed media data including at least the size information of the media data and the variable length code of the media data is input, the basic information and the media information are compressed into a predetermined media file format. A variable length code is multiplexed to generate a compressed media file format including a basic information multiplexing area, a size information multiplexing area, and a variable length code multiplexing area, and at least a predetermined portion of the basic information multiplexing area and the size information multiplexing Encryption apparatus comprising: an encryption area and an encrypted media file format creation section for encrypting a portion extending from the end of the size information multiplexing area to the beginning of the variable length code multiplexing area.
9. The media encryption device according to claim 8, wherein the encrypted media file format creation unit further encrypts a portion immediately before the size information multiplexing area in the compressed media file format.
9. The media encryption apparatus according to claim 8, wherein the encrypted media file format creation unit further encrypts an arbitrary portion other than the beginning of the variable length code multiplexing area in the compressed media file format.
9. The media compression unit according to claim 8, further comprising a media compression unit that compresses the media data and generates compressed media data including basic information including at least size information of the media data and a variable length code of the media data. Media encryption device.
The media encryption apparatus according to claim 8, wherein the encrypted media file format creation unit generates encrypted part information indicating an encrypted part.
Encryption obtained by further compressing compressed media data including a header area that stores basic information of the media data and a variable length code area that stores a variable length code of the media data. When compressed media data is input, an encryption / decryption processing unit that generates the compressed media data by decrypting at least a predetermined part of the header area and a part extending from the end of the header area to the beginning of the variable-length code area When,
A media encryption / decryption device comprising a media decompression unit for decompressing the compressed media data.
The encryption / decryption processing unit performs encryption / decryption of a head part of each header area in the encrypted compressed media data and a part extending from the end of each header area to the head of the variable-length code area. 14. The media encryption / decryption device according to 13.
The encryption / decryption processing unit performs encryption / decryption of a portion of the encrypted compressed media data that extends from immediately before each header region and a portion that extends from the end of each header region to the beginning of the variable-length code region. The media encryption / decryption device according to claim 13.
14. The encryption / decryption processing unit performs encryption / decryption of each header area in the encrypted compressed media data and a portion extending from the end of each header area to the beginning of the variable-length code area. Media encryption / decryption device.
14. The media encryption / decryption device according to claim 13, wherein the encryption / decryption processing unit further performs encryption / decryption of an arbitrary portion other than the beginning of the variable-length code area in the encrypted compressed media data.
When the encrypted part information indicating the encrypted part of the encrypted compressed media data is input together with the encrypted compressed media data, the encryption / decryption processing unit decrypts the part indicated by the encrypted part information The media encryption / decryption device according to claim 13.
Compressed media data including compressed media data and basic information including at least size information of the media data and a variable length code of the media data is further multiplexed and encrypted into a predetermined media file format. When an encrypted compressed media file format is input, a variable length code is generated from at least a predetermined portion of the basic information multiplexed area, a size information multiplexed area, and an end of the size information multiplexed area of the encrypted compressed media file format. An encryption / decryption processing unit that generates a compressed media file format by decrypting a portion straddling the head of the multiplexed area;
Analyzing the compressed media file format and generating the compressed media data;
A media encryption / decryption device comprising: a media decompression unit that decompresses the compressed media data generated by the media file format analysis unit.
The media encryption / decryption device according to claim 19, wherein the encryption / decryption processing unit further performs encryption / decryption of a portion immediately before the size information multiplexing area in the encrypted compressed media file format.
The media encryption / decryption device according to claim 19, wherein the encryption / decryption processing unit further encrypts an arbitrary portion other than the head of the variable-length code multiplexing area in the encrypted compressed media file format.
When the encrypted part information indicating the encrypted part of the encrypted compressed media file format is input together with the encrypted compressed media file format, the encryption / decryption processing unit decrypts the part indicated by the encrypted part information The media encryption / decryption device according to claim 19.
When compressed media data including a header area storing basic information of the media data and a variable length code area storing a variable length code of the media data is input, the encryption processing determination unit Is an encryption process determination step that specifies at least a predetermined part of the header area and a part that extends from the end of the header area to the beginning of the variable length code area as an encryption part
A media encryption method comprising: an encryption processing step, wherein an encryption processing unit encrypts a portion specified in the encryption processing determination step in the compressed media data.
The encryption processing determination step is characterized in that the beginning portion of each header area in the compressed media data and the portion extending from the end of each header area to the beginning of the variable length code area are specified as portions to be encrypted. The media encryption method according to claim 23.
The encryption processing determination step specifies a portion of the compressed media data that extends from immediately before the header area and a portion that extends from the end of each header area to the beginning of the variable-length code area as an encrypted portion. 24. The media encryption method according to claim 23.
24. The encryption processing determination step specifies each header area in the compressed media data and a part extending from the end of each header area to the beginning of the variable length code area as an encrypted part. The media encryption method described.
The media encryption method according to claim 23, wherein the encryption processing determination step further specifies an arbitrary portion other than the beginning of the variable length code area in the compressed media data as the portion to be encrypted.
A media compression step in which a media compression unit compresses media data and generates compressed media data including a header area storing basic information of the media data and a variable length code area storing a variable length code of the media data With
24. The media encryption method according to claim 23, wherein the encryption processing determination step encrypts the compressed media data generated in the media compression step.
24. The media encryption method according to claim 23, wherein the encryption processing step generates encrypted part information indicating the encrypted part.
When the compressed media data including the basic information including at least the size information of the media data and the variable length code of the media data is input, the encrypted media file format creation unit The basic information and variable length code are multiplexed in a media file format to generate a compressed media file format including a basic information multiplexing area, a size information multiplexing area, and a variable length code multiplexing area, and at least the basic information multiplexing area Encryption method including an encrypted media file format creating step for encrypting a predetermined portion of the size information multiplexing region and a portion extending from the end of the size information multiplexing region to the beginning of the variable length code multiplexing region .
The media encryption method according to claim 30, wherein the encrypted media file format creation step further encrypts a portion immediately before the size information multiplexing area in the compressed media file format.
The media encryption method according to claim 30, wherein the encrypted media file format creation step further encrypts an arbitrary part other than the head of the variable length code multiplexing area in the compressed media file format.
The media compression unit includes a media compression step of compressing the media data and generating compressed media data including basic information including at least size information of the media data and a variable length code of the media data,
The media encryption method according to claim 30, wherein the encrypted media file format creation step multiplexes and encrypts the compressed media data generated in the media compression step.
The media encryption method according to claim 30, wherein the encrypted media file format creation step generates encrypted part information indicating an encrypted part.
Encryption obtained by further compressing compressed media data including a header area that stores basic information of the media data and a variable length code area that stores a variable length code of the media data. When the compressed media data is input, the encryption / decryption processing unit encrypts and decrypts at least the predetermined part of the header area and the part extending from the end of the header area to the beginning of the variable-length code area to obtain the compressed media data. An encryption / decryption processing step to be generated;
A media encryption / decryption method comprising: a media decompression unit, wherein a media decompression unit decompresses the compressed media data.
The encryption / decryption step encrypts / decrypts the head portion of each header area in the encrypted compressed media data and the portion extending from the end of each header area to the head of the variable-length code area. The media encryption / decryption method described.
The encryption / decryption step encrypts / decrypts a portion of the encrypted compressed media data that straddles the head immediately before each header area and a portion that straddles the head of the variable-length code area from the end of each header area. The media encryption / decryption method according to claim 35.
36. The medium according to claim 35, wherein the encryption / decryption step decrypts each header area of the encrypted compressed media data and a portion extending from the end of each header area to the beginning of the variable-length code area. Encryption / decryption method.
36. The media encryption / decryption method according to claim 35, wherein the encryption / decryption step further includes encryption / decryption of an arbitrary portion other than the head of the variable-length code area in the encrypted compressed media data.
In the encryption / decryption processing step, when encrypted part information indicating the encrypted part of the encrypted compressed media data is input together with the encrypted compressed media data, the part indicated by the encrypted part information is decrypted. 36. The media encryption / decryption method according to claim 35.
Compressed media data including compressed media data and basic information including at least size information of the media data and a variable length code of the media data is further multiplexed and encrypted into a predetermined media file format. When the encrypted compressed media file format is input, the encryption / decryption processing unit includes at least a predetermined part of the basic information multiplexed region, the size information multiplexed region, and the size information multiplexed region of the encrypted compressed media file format. An encryption / decryption processing step for generating a compressed media file format by encrypting and decrypting a portion straddling the beginning of the variable-length code multiplexing area from the end of
A media file format analysis unit that analyzes the compressed media file format and generates the compressed media data; and
A media encryption / decryption method comprising: a media decompression unit, wherein a media decompression unit decompresses the compressed media data generated in the media file format analysis step.
42. The media encryption / decryption method according to claim 41, wherein the encryption / decryption processing step further performs encryption / decryption of a portion immediately before the size information multiplexing area in the encrypted compressed media file format.
42. The media encryption / decryption method according to claim 41, wherein the encryption / decryption processing step further encrypts an arbitrary portion other than the beginning of the variable-length code multiplexing area in the encrypted compressed media file format.
In the encryption / decryption processing step, when the encrypted portion information indicating the encrypted portion of the encrypted compressed media file format is input together with the encrypted compressed media file format, the portion indicated by the encrypted portion information is decrypted. 42. The media encryption / decryption method according to claim 41, wherein: