JP4860993B2 - Method and apparatus for protecting content packaging - Google Patents

Description

  The present invention relates to the field of multimedia content protection. More specifically, the present invention relates to a method for reporting protection information used in media files to implement random access and selective protection features with minimal overhead.

  DRM (Digital Rights Management) is becoming more and more important for content distribution and distribution. One-way broadcast with / without back channel, two-way content distribution via the Internet network, content via storage media such as DVD Distribution, including SD.

  The DRM consists of three main parts: key management and license delivery, usage rule notation, and protected content packaging. These can be combined together or separated.

  Of the three parts, only protected content packaging depends on the packaged format, eg, file format, system format, or RTP packet format.

  Such a content packaging format includes information such as header, metadata, media information, timing, and relationship between packets. Protection notifications and protection information must be defined and associated with the entire content or specific parts of the content.

  Such protection information can be used in other packaging to recognize how the terminal will extract the protection information in advance so that there is no delay or unpleasant user experience when using protected content. It is defined and stored with the format.

  In the protection information, the encryption method and its parameters, the content encryption method, the method of associating with the protected content, the key storage location, the license receiving method, and the like should be defined.

  In addition to the above considerations for a practical system, it is necessary to consider flexibility and extensibility when starting the design in order to maximize the interoperability between the DRM system and other systems.

  File format is one of the most popular content packaging formats used to store content for playback or to store content before sending it over an IP or wireless network. This format is an ISO-compliant media file format (ISO / IEC 14486-12) of Non-Patent Document 1 that has been used to deliver digital media data such as video, audio, images, text, graphics, etc. Is the basic file format, MP4 FF, AVC FF, MP21 FF, 3GPP FF, AVS (Chinese Audio Video System) FF, OMA DRM FF, ISMA Protection FF, etc. It is used as the basis for format.

In Non-Patent Document 2 and Non-Patent Document 3, DRM protection is defined based on MPEG-4 and MPEG-2 systems, and is called MPEG IPMP scheme. The IPMP scheme is mapped to ISO FF in Non-Patent Document 4, and an IPMP descriptor (Descriptor) is further defined in Non-Patent Document 5, and IPMP information is stored in an IPMP information box (Information Box) in a file based on ISO FF. The method to do is devised.
ISO / IEC 14496 ISO / IEC compliant file format, October 2002 (N5259) MPEG-4 IPMP, ISO / IEC 14496-13, Information technology-Coding of audio viewing objects-Part 13: Intellectual property management and protection (IPMP) extensions MPEG-2 IPMP, ISO / IEC 13818-11, Information technology-Generic coding of video and related audio information-Part 11: IPMP for MPEG-2 systems ISO / IEC 14496 ISO / IEC compliant file format correction 1, June 2004 (N6569) Patent draft "Method of media file protection" Z. Y. Huang, S.H. M.M. Shen, T. Ueno, 2005 ISMACrypt, ISMA DRM recommended version 1.0, Internet Streaming Media Alliance, 2570W. El Camino Real OMA DRM 2.0, DRM-DCF, DRM-REL, DRM-DRM specification V2.0 (draft version), September 2005

  The above prior art has the following problems.

  The file format consists of a lot of sample data, and each sample data is most often protected using the same method with the same or different key parameters. The same applies to the access unit when carrying content via the IP network.

  In certain mechanisms or protection notification methods, especially when using an IPMP compliant protection scheme for file format compliant content protection, it is necessary to provide and enable the above scenario with minimal overhead. Such protection notification methods provide random access and selective protection features.

  In Non-Patent Document 4 and Non-Patent Document 5, the above is not defined or provided.

  In Non-Patent Document 6 and Non-Patent Document 7, a notification method is defined, but when the key parameter is the same for each sample or access unit, the overhead required for each sample or access unit is excessive. .

  The present invention defines a protection notification to improve the prior art and solve the above-mentioned problems.

  An IPMP sample format box (IPMPSampleFormatBox) is defined below the sample input box and whether selective protection is employed, whether the key parameters are fixed for the sample you want to protect, and protection Indicates whether to store the common key parameter used for the desired sample.

  An IPMP sample header (IPMPSampleHeader) is further defined as a sample data header to describe whether the sample is protected and if so, what key parameters are stored and used .

  The same applies to the access unit. In this case, an IPMPAU format box (IPMPAUFormatBox) and an IPMPAU header (IPMPAUHeader) are defined to achieve the same purpose.

  The present invention provides an improvement over existing DRM solutions based on ISO compliant file formats. This is complementary in that it further extends the existing IPMP compliant DRM solution.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  1, 2, 3 and 4 show the prior art described below.

  FIG. 1 shows a top-level general-purpose file format structure, and this specification will be described using a China AVS (Audio / Video System) as an example. The file mainly consists of three boxes: a file type box 101, a moving picture box 102, and a media data box 104 ordered in real time and containing interleaved or non-interleaved video and audio frames.

  The actual video track box 103 must be contained within the video box 102. The handler type (handler_type) of the video track handler box (HandlerBox) must be “video”, and the 4-character code of the video track sample description must be “avsm” in the case of AVS FF. The media content packaged in the AVS-M media file shown in FIG. 1 is described in a plain text format.

  FIG. 2 shows a general protection scheme used in current ISO compliant file formats. The 4-character code in the sample description is replaced with a 4-character code indicating protection encapsulation. These codes differ only in the media type (for example, “encv” 201 of the video track). A protection scheme information box (ProtectionSchemeInfoBox) 202 is added to the sample description and all other boxes remain unchanged. The actual media data 203 is preferably in a converted format (for example, encrypted).

  A general protected AVS-M file structure is shown in FIG. This employs a general ISO-compliant file format protection scheme as shown in FIG. An example implementation of such ISO compliant file format protection for an AVS-M file is that the 4-character code in the sample description is replaced with a 4-character code indicating protection encapsulation, where “avsm” is “ encv "301. A protection scheme information box (ProtectionSchemeInfoBox) 302 is added to the sample description and all other boxes remain unchanged. Most importantly, the original sample input type (4-letter code “avsm”) is stored in a protection scheme information box (ProtectionSchemeInfoBox) of a new box called the original format box (OriginalFormatBox).

  The protection scheme information box (ProtectionSchemeInfoBox) contains all converted information (eg, applied encryption method and its parameters, general DRM module name and information), and other information such as the type and location of the key management system. Including protection information. It also records the original (unencrypted) format of the media. As shown in FIG. 4, the protection scheme information box 401 is a container box, and is composed of four boxes: an original format box 402 (required), an IPMP information box (IPMPInfo Box) 403 (required), A scheme type box 404 (arbitrary) and a scheme information box 405 (arbitrary) are included. The protection scheme information box 401 is essential in the sample input using 4CC indicating the protected stream.

When used in a protected sample input, the box must contain a source format box that records the source format. It is also necessary to identify the applied protection using at least one of the following notification methods.
1) Stand-alone IPMP: IPMP information box (IPMPInfoBox) (when using IPMP description outside the MPEG-4 system)
2) Scheme notification: scheme type box (SchemeTypeBox) and scheme information box (SchemeInformationBox) (if they are used, but both will always occur or not occur at all).
aligned (8) class ProtectionSchemeInfoBox (fmt) extends Box ('sinf') {
OriginalFormatBox (fmt) original_format;
IPMPInfoBox IPMP_descriptors; // optional
SchemeTypeBox scheme_type_box; // optional
SchemeInformationBox info; // any}

  As shown in FIG. 4, the IPMP information box stores IPMP-compliant protection information related to all protected samples under the track.

  Whether each sample under the track is protected, what protection parameters are used, and what key parameters are specifically for each sample when the encryption method is declared and defined in the IPMP information box Whether it is used or not is defined as shown in FIG.

  The IPMP information box shown at 502 is below the protection scheme information box, while the protection scheme information box is below the sample description box 501. The encrypted data is shown at 503.

  The IPMP sample format box (IPMPSampleFormatBox) is defined in 504, and is preferably applied to the sample data 503 stored in the IPMP information box (IPMPInfoBox) 502 and encrypted under the same track. In 505, the IPMP sample header 1 (IPMPSampleHeader1) stores the IPMP-compliant protection information specific to the encrypted sample data 506 (EncryptedData1) that is a part of the encrypted media data 503 that follows the IPMP sample header 1 Is defined accordingly. The same method is applied to other sample data. The IPMP sample format box (IPMPSampleFormatBox) and the IPMP sample header (IPMPSampleHeader) define goals for solving the challenges of sample protection and selective encryption with less overhead.

  A general flow diagram is shown in FIG. 6 to illustrate how the sample data is protected and how to retrieve the protection parameters used for each sample.

  In 601 of FIG. 6, the IPMP sample format box (IPMPSampleFormatBox) is confirmed by the terminal, and information such as a fixed parameter flag (Fixed_Parameters) 602 and a selective protection flag (Selective_Protection) 606 is searched.

  If the fixed parameter flag (Fixed_Parameters) is set to 0 at 603, each protected sample has its own set of parameters obtained from the IPMP sample header (IPMPSampleHeader) for each protected sample at 604. Meaning, if non-zero, the fixed parameter set stored at 605 is obtained and used for all protected samples under the same track.

  If the selective protection flag is set to 0 at 607, all samples under the track are protected and other protection flags in the IPMP sample header (IPMPSampleHeader) are set for each sample described in 608. This means that there is no need to search. If the value is other than 0, in 609, another protection flag stored in the IPMP sample header (IPMPSampleHeader) arranged at the head of each sample is searched.

  If the protection method is encryption and the AES counter mode is selected, the fixed parameter flag (Fixed_Parameters) can be a fixed key parameter flag (Fixed_KeyParameters), and the selective protection flag (Selective_Protection) is optional. It can be an encryption flag (Selective_Encryption).

The syntax of the IPMP sample format box (IPMPSampleFormatBox) shown in FIGS. 5 and 6 can be further defined as follows when the AES counter mode is used for protection.
aligned (8) class IPMPSampleFormatBox extends FullBox ('iSFM', 0, 0) {
bit (1) Selective_Encryption;
bit (1) Fixed_KeyParameters;
bit (6) reserved;
unsinged int (8) Key_Indicator_Length;
unsigned int (8) IV_length;
if (Fixed_KeyParameters == 1) {
unsigned int (8 * IV_length) IV;
unsigned int (8 * Key_Indicator_Length) Key_Indicator;}
}

  The first bit indicates whether a selective encryption flag is used for the sample. The second bit indicates whether or not the fixed key parameter flag is used for all samples under the track. If so, the following two parameters, IV (initial vector) and key indicator (Key_Indicator) will be the same for all samples in this example, otherwise such information for all samples: Must be provided.

This method is also applied to an access unit in which an IPMPAU format box (IPMPAUFormatBox) is defined.
aligned (8) classIPMPAUFormatBox extends FullBox () {
bit (1) Selective_Encryption;
bit (1) Fixed_KeyParameters;
bit (6) reserved;
unsigned int (8) Key_Indicator_Length;
unsigned int (8) IV_Length;
if (Fixed_KeyParameters == 1) {
unsigned int (8 * IV_length) IV;
unsigned int (8 * Key_Indicator_Length) Key_Indicator;}
}

The syntax of the IPMP sample header (IPMPSampleHeader) shown in FIGS. 5 and 6 can be further defined as follows when the AES counter mode is used for protection.
aligned (8) class IPMPSampleHeader {// This is under each sample
if (Selective_Encryption == 1) {// From sample description
bit (1) Sample_Is_Encrypted;
bit (7) reserved;
}
else Sample_Is_Encrypted = 1;
if (Sample_Is_Encrypted == 1) {
if (Fixed_KeyParameters == 0) {// Read subsequent bits and get IV and key indicators for each sample //
unsigned int (8 * IV_length) IV;
unsigned int (8 * Key_Indicator_Length) Key_Indicator;
}
else // Get fixed key parameter flag defined at sample description level / IPMP sample format box
}

  If the selective encryption flag is set to 1, the first bit of each sample is obtained, the sample encryption flag (Sample_Is_Encrypted) is set to 1 or 0 according to the bit, and the selective encryption flag is set to 1. If not set, the sample encryption flag (Sample_Is_Encrypted) is set to 1.

  In the case of encrypted samples, if the fixed key parameter flag (Fixed_KeyParameters) is invalid, the IV and key indicator (Key_Indicator) are set to each sample data according to 8 * IV length (IV_length) and 8 * key indicator length (Key_Indicator_Length). If it is not invalid, such data is obtained from the IPMP Sample Format Box (IPMPSampleFormatBox) and notified to all protected sample data under the track.

The same method applies to access unit protection.
aligned (8) class IPMPAUHeader {
bit (1) EncryptedAU; // Encryption indicator
bit (7) reserved; // must be zero
if (EncryptedAU == 1) {
if (Fixed_KeyParameters == 0) {// read subsequent bits and get // IV and key indicator for each sample
unsigned int (8 * KeyIndicatorLength) Key_Indicator;
unsigned int (8 * IVLength) IV;
}
else // Get fixed key parameter /// data flag defined in IPMPAU format box
}

  FIG. 7 shows a procedure for the server to generate a protected file. First, the content server or creator 701 generates and formats each sample data with protection information such as an IPMP sample header (IPMPSampleHeader) at 711, and sets individual parameters for each protected sample data. If a set is used, at 712 the parameter set is stored in an IPMP sample header (IPMPSampleHeader).

  The IPMP sample format box (IPMPSampleFormatBox) is generated by storing the fixed parameter flag and the selective protection flag in the IPMP sample format box (IPMPSampleFormatBox) shown in 713. At the same time, when a fixed parameter (Fixed_Parameter) is used for all protected sample data under the same track, the protection parameter set is stored in the IPMP sample format box (IPMPSampleFormatBox).

  Use default cryptographic algorithms, key management systems, and rights data related information 703 to represent any rights protected DRM module and rights related information 702, or use only a specific IPMP tool (IPMP Tool) to create an IPMP descriptor By constructing (IPMP Descriptors), an IPMP information box (IPMP Info Box) is generated.

  A plurality of IPMP descriptors constructs an IPMP information box 704, which box further includes original format box 705 information (ie, 4cc representing the original unconverted sample input coding name in the case of AVS-M). The information protection scheme information box 706 is formed together with “avsm”). The protection scheme information box further forms a Movie Box 708 with Sample Description Box 707 information (ie, 4cc “encv” indicating that the declared video sample is protected). .

  Finally, the media data box (Media Data Box) 709 and the converted (eg encrypted) media data contained in the video box are packaged with the file name “avs1” and protected. An AVS-M file 710 is formed and is ready for download or streaming by the end user.

  FIG. 8 shows a procedure for a terminal or device that plays a protected file downloaded or streamed from a server.

  When the terminal 801 downloads or streams the file 802 from the server, the first step is to extract the 4cc information stored in the sample description box 805 of the moving picture box 804. For example, if “avsm” is detected when AVS-M is stored as media data, the actual media data is in plain text format, and the media data stored in the AVS-M data box 803 is used. The terminal can play directly.

  If “encv” is detected, the actual acquired data stored in the AVS-M data box 803 is in a converted (eg, encrypted) format and cannot be directly reproduced. Further steps are required to obtain the information stored in.

  If the default encryption algorithm, the key management system, and the right data related information 808 can be extracted from the IPMP descriptor declared in the IPMP information box 807 in the protection information box, the terminal performs the information in steps 811 to 814 below. Is used to obtain a key, license, etc., and decrypt and reproduce plaintext AVS-M video data.

  If only unique IPMP tool information and rights-related data 809 are extracted from the IPMP descriptor 807, the terminal will download the actual DRM (with special IPMP identifier) downloaded from any location in the following steps 811 to 814. Module 810 is executed to reproduce the inverse transform (eg, decryption) and plaintext AVS-M video data.

  In 811, a fixed parameter (Fixed_Parameter) and a selective protection flag (Selective_Protection) are obtained from the IPMP sample format box (IPMPSampleFormatBox), and a fixed protection parameter is also obtained from here to obtain all protected samples under the track • Used for data.

  At 812, if the selective protection flag (Selective_Protection) is valid, a protection flag bit is obtained. In 813, if an individual protection parameter set is used for each protected sample, a protection parameter set such as a key parameter set for encryption is obtained from the IPMP sample header (IPMPSampleHeader), otherwise The set of fixed protection parameters can be obtained from the IPMP Sample Format Box (IPMPSampleFormatBox).

  Finally, at 814, unprotected media data is played.

  The present invention is applicable to the field of application of digital media files, and is particularly applicable to notification of protection information that controls the generation, distribution, and use of media files, particularly AVS-M files.

The plain text AVS-M file structure is shown. Figure 2 illustrates a general ISO compliant file format protection scheme for a video track. A general protected AVS-M file structure is shown. A protection scheme information box that uses all of its sub-boxes for AVS-M file protection is shown. The protected file structure is shown up to the protected sample data whose header uses IPMP compliant protection. FIG. 10 shows a flow chart when extracting and using a protection flag and a parameter from an IPMP sample format box (IPMPSampleFormatBox) and an IPMP sample header (IPMPSampleHeader). The procedure for the server to create a protected file is shown. The procedure for a terminal or apparatus to reproduce a protected file is shown.

Explanation of symbols

101 File type box 102 Movie box 103 Video track box 104 Media data box 105 (No mention)
106 Video track handler box 107 (No mention)
201 Media type 202 Protection scheme information box 203 Media data 301 (No mention)
302 Protection scheme information box 303 (no mention)
401 Protection scheme information box 402 Original format box 403 IPMP information box 404 Scheme type box 405 Scheme information box 501 Sample description box 502 IPMP information box 503 Encrypted data 504 IPMP sample format box 505 IPMP sample header 1
506 Encrypted data 1
601-609 (No mention)
701 Content server or creator 702 Optional rights-protected DRM module and rights-related information 703 Default encryption algorithm, key management system, and rights data-related information 704 IPMP information box 705 Original format box 706 Information protection scheme information box 707 Sample description Box 708 Movie box 709 Media data box 710 Protected AVS-M file 711-713 (No mention)
801 Terminal 802 File 803 AVS-M Data Box 804 Movie Box 805 Sample Description Box 806 Protection Scheme Information Box 807 IPMP Information Box 808 Default Cryptographic Algorithm, Key Management System, and Rights Data Related Information 809 Specific IPMP Tool Information and Rights Related Data 810 Actual DRM module downloaded from any location (with special IPMP identifier) 811-814 steps

Claims (3)

A recording method for recording content data in a file,
Separating content data into content and an encryption key used to encrypt the content;
The encryption key encrypts the content in sample units or access units, and records information for acquiring the encryption key in the IPMP information box area in the file in sample units or access units When,
A step of the content, prior SL using encryption key, said encrypted in sample units or access units, it is recorded to the region of the media data box of the file,
A content recording method comprising: When the content recorded in the media data box has at least a plurality of samples or access and an encryption key is common, the common encryption key is recorded in the IPMP sample format box of the IPMP information box, and the IPMP sample format box The fixed key parameter flag in
The content recording method according to claim 1. A selective encryption flag indicating whether or not the content recorded in the media data box is encrypted in sample units or access units is recorded in the IPMP sample format box of the IPMP information box,
The content recording method according to claim 1.

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