JP2006042108A - Decoding method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To demarcate a cause when a video is not reproduced correctly in spite of the correct combination of content data and key data when the content data encrypted by a video receiver is decoded and reproduced. <P>SOLUTION: In the video receiver, an encrypted video content is received, decoded, processed, and reproduced. In the video receiver, encrypted data for verification contained in the received encrypted video content and data for the verification of a plaintext are extracted. In the video receiver, data of a result obtained by conducting the same decoding processing as the decoding processing applied to the encrypted video content to the extracted encrypted data for the verification are compared and collated with the data for the verification of the plaintext. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a decryption method and apparatus capable of verifying the consistency between encrypted content and key data in decryption processing of encrypted content data.

  In recent years, DRM (Digital Rights Management) technology that protects the rights of content data in various forms has been proposed. As an example of this, there is a method of separately managing license data consisting of usage condition information of encrypted content data and key data for decrypting the content data, and encrypted content data. There is a feature that a flexible license distribution is possible even after conversion (see, for example, Patent Document 1). In addition, a technique has also been proposed in which key data is embedded in encrypted content data and distributed, and falsification of the encrypted content data and key data is detected (see, for example, Patent Document 2). Regardless of which method is used, it can be said that a method for uniquely associating encrypted content data with key data for decrypting the content data has been established.

  However, for example, for a video reception device (such as a set-top box with a network reception function) that receives and plays back video content such as movies and TV dramas via the Internet, the combination of content data and key data is uniquely guaranteed. It is not enough. When the content distribution side is limited as in TV broadcasting, it is possible to perform sufficient verification in advance on the distribution side and the receiving device side, but in Internet broadcasting, an unspecified number of content providers enter the market. Therefore, it is virtually impossible to confirm the reproduction of all contents in advance. Although there are standards that should be complied with for encryption and decryption processing, in reality, differences in encryption parameters, differences in key data application procedures and byte orders, differences in interpretation of standards, encryption devices・ Even if there are uncertain factors such as differences due to the implementation of the decryption device and the combination of content data and key data is correct, the video reception device cannot perform the decryption process correctly, resulting in video playback. The problem of not being generated.

Since the decrypted content data is a simple data string, the video receiving apparatus alone cannot determine whether or not the decryption processing has been performed correctly. Also, since it seems that the user simply fails to reproduce the content data, whether it is a failure of the video receiving device, cannot be reproduced due to a user setting error, or is there another factor (purchased content data The video receiver does not support this encryption method), and the cause cannot be isolated. The user can only contact the manufacturer of the video receiver or the content provider, but the manufacturer knows whether the correspondence between the encrypted content data and the key data is correct or incorrect, and the content provider is the same. Yes, no further causes can be identified. For users, this is a major issue in terms of convenience, and for video receiver manufacturers and content providers, it is a major issue in terms of operation and support, such as refunds after they have been charged, and repairs and inspections of video receivers. It was.
JP 2004-48533 A JP 2000-122536 A

  The problem to be solved is that when the content data encrypted with the video receiving device is decrypted and played back, the video is not played back correctly even though the combination of the content data and the key data is correct. The cause could not be determined.

  The present invention embeds the encrypted verification data and plaintext verification data in the encrypted content data, and the video receiving device decrypts the encrypted verification data, and cleartext verification data and Matching is the main feature.

  In the decryption method and apparatus of the present invention, it is possible to compare and collate data obtained as a result of actually decrypting encrypted verification data with plain text verification data. When content data reproduction fails, there is an advantage that it is possible to determine the cause due to differences in encryption processing procedures between the encryption device and the decryption device, such as differences in encryption parameters and standards.

(Embodiment 1)
Hereinafter, an embodiment in which the present invention is applied to video content distribution such as a predetermined movie or TV drama will be described with reference to the drawings. FIG. 2 is a configuration example of a video content distribution system. The content provider 201 performs an encryption process on the video content stored in the video content database 202 by the encryption device 204 so that only a predetermined recipient can view the video content. The network can transmit and receive data, and for example, a TCP / IP communication protocol may be used. The encrypted video content is distributed from the video distribution server 205 to the video receiving device 206 via the network. The key data used for encrypting the video content is managed by the key data management server 203 and distributed to the video receiving device 206 via the network in the same manner as the video content. The video receiving device 206 receives the encrypted video content and key data via the network interface unit 207, and the decryption processing unit 208 performs decryption processing. The plaintext video content after the decoding process is decoded by the video decoder unit 209 and reproduced by the screen display unit 210.

  Next, a description method of symbols related to encryption / decryption of video contents will be described. The plaintext video content is written as F, the plaintext verification data is written as M, and the key data for encrypting the video content F is written as K. The encryption process using the key data K is written as EncK (). For example, video content encrypted with K is written as EncK (F). The decryption process using the key data K is written as DecK (). For example, data obtained as a result of decrypting EncK (F) with key data K is written as DecK (EncK (F)). If the processing of EncK () and DecK () is both correct, then DecK (EncK (F)) = F holds.

  FIG. 3 is a diagram showing an embodiment of a packet format used for video content distribution. The packet is composed of a header part 301 and a payload part 302. The header portion 301 is provided with a field for determining the type of data stored in the payload portion 302 in addition to various header fields. The content data / verification data discrimination field 304 is a field for discriminating content data and verification data. The encryption / plaintext discrimination field 303 is a field for discriminating between encrypted data and plaintext data. In this embodiment, the packet header information is used to distinguish content data and verification data, and encrypted data and plaintext data. However, other means are used to distinguish data. You may do.

  FIG. 4 shows an example in which the encrypted content EnkK (F), the encrypted verification data EncK (M), and the plaintext verification data M are packet-multiplexed. Here, for convenience, the packet multiplexed stream (S) is written. Note that the verification data M is not necessarily provided separately from the content data, and a part of the content data may be used as the verification data as it is.

  Next, an embodiment of the decoding processing unit 100 according to the present invention will be described with reference to FIG. The decryption processing unit 100 performs processing using the multiplexed packet stream S and the key data K as input data. The demultiplexer 101 refers to the header information of each packet of the multiplexed packet stream S and separates the verification data and the content data. Further, by separating each into encrypted data and plaintext data, a process of demultiplexing into a total of four types of packets is performed. That is, the packets storing F, EncK (F), M, and EncK (M) are output.

  When EncK (F) is input, the decryptor 105 performs decryption processing using the key data K and outputs DecK (EncK (F)). When EncK (M) is input, the decryption process is similarly performed using the key data K, DecK (EncK (M) is output, and the output result is input to the collator 106. The collator 106 is the DecK. (EncK (M)) and verification data M input from the demultiplexer 101 are compared and collated, and the determination result (match or mismatch) is output.In this embodiment, the collator of the video receiving apparatus. 106, M and DecK (EncK (M)), for example, using a user's remote control operation or a video streaming communication protocol (RTSP: Realtime Streaming Protocol) KeepAlive. May be sent back to the server via the network and collation may be performed on the server side.

  FIG. 5 is an example of a processing flowchart of the video receiving apparatus. Using the determination result information output from the collator, it is possible to display an error message to notify the user of the reason why the video is not reproduced. FIG. 6 is an example of an error message displayed on the screen. In addition, it is also possible to display an error code instead of an error message to notify a more detailed error factor.

  FIG. 7 shows an example of the verification data. The verification data EncK [i] (M [i]) encrypted with the encryption method i (i = 1, 2,..., N) and , Corresponding plain text verification data M [i]. By using the verification data as such a reference, it is possible to check the encryption method that can be supported by the receiving terminal.

  FIG. 8 shows an example of the verification data. In the encrypted verification data EnkK [i] (M [i]), the position information of the corresponding plaintext verification data M [i] is included. Embedded. By using such verification data, the position of the plaintext verification data M can be arbitrarily changed, and the security strength can be increased.

  FIG. 9 is an example of a processing flowchart of the video receiving apparatus. If the audio (video) notifying that the key is different is sent as plain audio as the second audio (or video) and it turns out that the decryption process has failed, the second audio (video) is automatically generated. By decoding without decoding, it is possible to notify the user that the decoding process has failed.

  FIG. 10A shows an example of a multiplexed packet stream, in which encrypted and plain video content data are alternately repeated. When such video content is played back, the video can be seen in detail, so that the user can visually check whether or not the decoding process has been performed correctly. In FIG. 10B, only video content is encrypted, and audio content is a plaintext packet multiplexed stream. In FIG. 10C, only MPEG2 I frames are plain text, and P frames and B frames are encrypted packet multiplexed streams. In each case, it is possible to confirm whether or not the decoding process is correctly performed by confirming the sound or by viewing the image as if it is flipping.

  Copyright management technology is an indispensable requirement for practical use of video streaming distribution, and the present invention is useful for its operation and support.

The block diagram which shows the decoding apparatus concerning one embodiment of this invention 1 is a configuration diagram showing a video content distribution system according to an embodiment of the present invention. The figure which shows the packet format concerning one embodiment of this invention. The figure which shows the packet multiplexed stream concerning one Embodiment of this invention Processing flowchart of decoding apparatus according to an embodiment of the present invention The figure which shows the error message displayed on the video receiver concerning one Embodiment of this invention The figure which shows the structural example of the data for verification concerning one Example embodiment of this invention. The figure which shows the structural example of the data for verification concerning one Example embodiment of this invention. Processing flowchart of decoding apparatus according to an embodiment of the present invention The figure which shows the packet multiplexed stream concerning one Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Decoding processing part 101 Demultiplexer 102 Content / verification data discriminator 103,104 Encryption / plaintext discriminator 105 Decoder 106 Collator

Claims (5)

In a video receiving apparatus that receives encrypted video content, performs decryption processing and reproduces the encrypted verification data included in the received encrypted video content, and plaintext verification data Data obtained by performing the same decryption process as the decryption process applied to the encrypted video content on the extracted verification data extracted, and the plaintext verification data A decoding method characterized by comparing and collating with. In a video receiving apparatus that receives encrypted video content, performs decryption processing and reproduces the encrypted verification data included in the received encrypted video content, and plaintext verification data Data obtained by performing the same decryption process as the decryption process applied to the encrypted video content on the extracted verification data that has been extracted, and the plaintext verification data A decoding apparatus characterized by comparing and collating. A plurality of verification data encrypted using different encryption methods and corresponding plaintext verification data included in the received video content are extracted, and each of the verification data is sequentially verified. 2. The decoding method according to claim 1, wherein processing is performed and the result is output. When the plaintext video content or the plaintext audio content is received simultaneously with the encrypted video content, and the verification result of the verification data does not match, the plaintext video content or the plaintext audio content is received. The decoding method according to claim 1, wherein the content is reproduced. The data obtained as a result of performing the same decryption processing as the decryption processing applied to the encrypted video content on the encrypted verification data is transmitted to a predetermined server. The decoding method according to 1.

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