JP2007013782A - Method for protecting media file - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for protecting a media file useful for protection of multimedia content. <P>SOLUTION: The method to signal DRM information in an AVS-M file is disclosed in the present invention. Following the general ISO base media file format box structure to achieve the interoperability and compatibility, the default encryption algorithm and related key management information in an IPMP descriptor is defined and carried in a required protection scheme box. The general IPMP signaling scheme through an IPMP tool ID declared by the IPMP descriptor as well is provided to achieve the flexibility in case the default protection scheme is broken or multiple DRM modules are desirable to protect such one video data. Rights data information to facilitate getting the actual usage rule for the content is also provided. The original content type of the media is kept in the new protected media form. Such file is useful to interchange, edit and playback for AVS-M video, especially for its IP protection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to the field of multimedia content protection. More specifically, the present invention relates to a protection information notification method used in a media file (that is, an AVS-M file).

  With the rapid and large-scale emergence of digital media resources, there is an increasing desire for users to use and access digital content more easily. File format is one of the most important content packaging means for delivering digital media data (content produced for video, audio, images, text, graphics and other digital devices). The general ISO compliant media file format (ISO / IEC 14496-12) is a standard format to which the majority of other media files conform.

  The AVS group is currently developing highly efficient, robust and scalable audio / video coding algorithms and tools. One of the developed video standards, called AVS-M, is video coding for mobile communications, interchangeable digital storage media, broadband video, multimedia e-mail, multimedia services over packet networks Standard for other applications. In conjunction with the development of this video standard, other standard parts of AVS (AVS-M file format) define storage formats that can be used as independent parts and inherit the characteristics, features and applications of every ISO FF Therefore, the AVS-M video content stored according to the ISO compliant file format is adjusted. However, it is also permitted to use AVS-M video content with other application standards, such as wireless streaming application standards.

  However, the fact that digital media resources can be easily replicated and easily distributed illegally becomes an obstacle to accepting the standardized AVS-M file format. In order to prevent such duplication or unauthorized distribution, the format can be encrypted using encryption and managed by a designated license. However, since there is no common format or DRM solution for storing such protection and rights management information, widespread use is impeded.

Accordingly, an object of the present invention is to provide means for notifying all protection information in an AVS-M file.
ISO / IEC 14496 ISO / IEC base file format, October 2002 (N5259) ISO / IEC 14496 ISO / IEC Base File Format Addendum 1, June 2004 (N6569)

  The above prior art has the following problems.

  The media content contained in the AVS-M media file is in an unprotected (unencrypted) format and may be illegally copied and / or illegally distributed by the user. This is an impediment to the feature of secure distribution and storage of coded AVS-M content that is increasingly demanding from content providers.

  The ISO compliant media file format that the AVS-M file format conforms to is a general infrastructure (for example, protection scheme information box (Protection Scheme InfoBox)) to protect the media declared by the ISO compliant media file format or its extended media file format. Have provided.

  However, there is no detailed protection information designated as a general structure that can be used appropriately to protect the AVS-M file format. This is, for example, the type of encryption algorithm to be used, in which case general key management information must be sent to the actual key management procedure to support it, and media playback is performed. The license-related rights information or usage rules to be defined in the above-mentioned box platform.

  The present invention makes it possible for the AVS-M file packaging function to use means for placing all the protection information in the generated AVS-M file for safe distribution or storage. The present invention also provides that when the receiving function recognizes that the media stored in the received file is under control, the AVS-M file receiving function or the reproducing function may It must be possible to track and extract protection information in the file format box structure for protection. Such a mechanism must also be easily extendable to protection of other AVS file formats that will appear in the future (eg AVS1.0 video, AVS1.0 audio, AVS-M audio, etc.).

  The present invention solves the above-mentioned problems by improving the prior art using a rational method.

  It provides a method for defining a new set of data structures extended from the ISO compliant file format “box” and notifying information about the converted (eg encrypted) AVS-M file format.

  The original content type of the media (ie AVS-M video) is stored in a new protected media format.

  In order to facilitate the actual decryption process, information on default encryption details (eg, encryption method and corresponding parameters) is provided. In order to facilitate the actual key management process, information about the default key management system used for the protection of the AVS-M file is provided.

  General DRM module information is provided through the IPMP tool ID declared in the IPMP descriptor to facilitate downloading of the actual DRM module used.

  In order to facilitate actual license acquisition, information relating to right information associated with the AVS-M file is provided.

  The present invention provides a DRM solution useful for protecting media content packaged using AVS-M files with the necessary protection information. The present invention also facilitates acquisition of protected information necessary for the user terminal to combine and play unprotected media resources. Protection details for encryption details, key management system, license query, general IPMP tools used, etc. are logically defined in a structured file format box.

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

  1 and 2 show the prior art.

  FIG. 1 shows the structure of a general AVS-M file format at the highest level. The general nature of the ISO media format is fully implemented by AVS-M files. The AVS-M file mainly includes a file type box 101, a moving image box 102, and a type of media data box 104 including an actual AVS-M video frame arranged in time order and interleaved. The primary brand indicator 105 of the AVS-M file format must be “avs1”. The actual AVS-M video track box 103 must be included in the video box 102. The handler type (handler_type) for the AVS-M video track handler box (HandlerBox) 106 must be “video”, and the 4-character code of the sample description of the AVS-M video track must be “avsm”. The media content packaged in the AVS-M media file shown in FIG. 1 is in an unprotected format.

  The ISO compliant media file format that the AVS-M file format is compliant has provided a general basis for protecting media tracks. FIG. 2 illustrates such a general protection scheme for use with 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 only differ depending on the media type (eg, “encv” 201 for a video track). A protection scheme information box 202 has been added to the sample description, but all other boxes remain unchanged. The actual media data 203 must be in a converted format (eg, encrypted).

  In the present invention, 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 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”. It is replaced with 301. A protection scheme information box 302 has been added to the sample description, but all other boxes remain unchanged. The most important point is that the original sample input type (4-letter code “avsm”) is stored in the protection scheme information box, that is, in a new box called the original format box (OriginalFormatBox). Details regarding the information stored in the protection scheme information box are defined below. The mechanism disclosed in the present invention can also be applied to other AVS file track protection (eg, AVS1.0 video, AVS1.0 audio, AVS-M audio, etc.) in the future.

・ Protection Scheme Information Box (Protection Scheme Information Box)
The protection scheme information box contains all converted information (eg applied encryption method and its parameters, general DRM module name and its information), and other protection information such as the type and location of the key management system . This also records the original (unencrypted) form of the media. As shown in FIG. 4, the protection scheme information box 401 is a container box and includes four boxes: an original format box 402 (required), an IPMP information box (IPMP Info Box) 403 (required), and a scheme type box (Scheme). (Type Box) 404 (optional), and a scheme information box 405 (optional). The protection scheme information box 401 is essential for sample input using a four-character code indicating a protected stream.

If this box is used in a protected sample input, the original form box must be included to record the original form. In addition, at least one of the following notification methods must be used to identify the protection applied:
1) Stand-alone IPMP: IPMP information box if IPMP description outside MPEG-4 system is used 2) Scheme notification: If these are used, scheme type box and scheme information box (both are mandatory, or Neither required)

aligned (8) class ProtectionSchemeInfoBox (fmt) extends Box ('sinf') {
OriginalFormatBox (fmt) original_format; // optional IPMPInfoBox IPMP_descriptors; // optional SchemeTypeBox scheme_type_box / // optional SmInfoInformat /

  Details of the actual notification method used to protect the AVS-M file will be disclosed later in the present invention.

-Original format box The original format box 402 contains the four-character code of the original unconverted sample description.
aligned (8) class OriginalFormBox (codingname) extends Box ('frma') {
unsigned int (32) data_format = codingname;
}
The data format (data_format) is a 4-character code of the original unconverted sample input, and in this case, it is necessary to take a value of “avsm”.

Notification method The IPMP information box is an essential item, and when a plurality of IPMP tools are used, a “global” IPMP control box (IPMPControlBox) must also be generated in the “moov” atom. The IPMP protection infrastructure provides a flexible and interoperable notification scheme for media protection purposes. The IPMP tool is a DRM module that performs IPMP functions such as authentication, decryption, and digital watermarking. A given IPMP (DRM) tool may coordinate other IPMP (DRM) tools. Each IPMP tool has a unique IPMP tool ID that uniquely identifies the tool at the presentation level or universal level. To be robust, IPMP can be updated with tools, thereby addressing security failures. In order to make the structure flexible, IPMP is allowed to use various IPMP tools including cryptographic tools.

  AVS-M file is not intended to be fixed in a single protection scheme (ie, it does not use any specific standard or non-standard encryption method, or any specific watermarking scheme), IPMP notification method This is the case. However, by specifying a default IPMP descriptor with a detailed encryption algorithm and other information associated with it (eg key information, selective encryption, etc.), other standardized DRM files (eg ISMACrypt and OMA DRM 2.0 PDCF) As such, actual implementation can be facilitated. Other protection information such as license information and key management system information can also be notified in the IPMP information box.

IPMP information box The IPMP information box contains one or more IPMP descriptors that record the protection applied to the stream. The IPMP descriptor (IPMP_Descriptor) is defined in the MPEG-4 IPMP system. However, if the IPMP descriptor is used in an ISO compliant media file format, it is stored directly in the IPMP information box and does not require any other MPEG-4 system functionality. Each IPMP descriptor has an IPMP tool ID (IPMP_ToolID) that identifies an IPMP tool essential for protection. Because an independent registration authority (RA) is used, anyone can register their IPMP tool and identify it without collision. The IPMP descriptor stores IPMP information for one or more IPMP tool instances included in the IPMP descriptor, but is not limited to IPMP right data, key management system data, IPMP key data, tool setting data, and the like.
aligned (8) class IPMPInfoBox extends FullBox ('imif', 0, 0) {
IPMP_Descriptor ipmp_desc [];
}
class IPMP_Descriptor () extends BaseDescriptor: bit (8) tag = IPMP_DescrTag
{
bit (8) IPMP_DescriptorID;
unsigned int (16) IPMPS_Type;
if (IPMP_DescriptorID == 0xFF && IPMPS_Type == 0xFFFF) {
bit (16) IPMP_DescriptorIDEx;
bit (128) IPMP_ToolID;
bit (8) controlPointCode;
if (controlPointCode> 0x00) bit (8) sequenceCode;
IPMP_Data_BaseClass IPMPX_data [];
}
}
IPMP_descr is an array of IPMP descriptors.

  When using multiple encryption algorithms (including some non-standard encryption algorithms), watermarking tools to enhance file protection, multiple IPMP descriptors with different IPMP tool IDs can be specified to provide protected AVS -Can be associated with M video streams.

  If the AVS-M video stream is popular or protected by standard cryptographic algorithms, a default IPMP descriptor has been defined and is shown in FIG. The IPMP descriptor IDEx 501 defines a pointer to the AVS-M video stream. The IPMPID of the default AVS-M encryption / decryption tool is registered together with its own IPMP tool ID 0x1111 (502) by AVS. If AES mode 503 = 0x01, an AES symmetric cipher according to the definition of NIST 128-bit key cipher block chaining mode (CBC) that has a 128-bit initialization vector prefixed to the ciphertext and is padded based on RFC2630 Is used. When AES mode 503 = 0x02, AES symmetric encryption is used according to the definition of NIST 128-bit key counter mode (CTR). A 128-bit IV is constructed without padding using a unique counter prefixed to the ciphertext. The IV length 504 defines the length of the IV preceding the access unit. Selective Encryption 505 provides an encryption indicator (0 indicates AU is unencrypted, 1 indicates AU is encrypted). The key indicator length (KeyIndicatorLength) 506 defines the length of the key indicator in bytes. A flag 507 called isKeyURL is used to mark whether the key data is declared by the URL or directly stored in the descriptor.

  If license information (direct rights / usage rule information or its URL) is also stored in the file box, as shown in FIG. 6, another IPMP is stored in the IPMP information box to store such information. Descriptors need to be defined. In this IPMP descriptor, the value 0x0000 of the IPMP tool ID 601 in this case is used to indicate that the IPMP tool is not returned, but the device returns the corresponding right data. The value 0x00 of the control point (ControlPoint) 602 means that the control point is not applied in this case. A flag 603 called isRightsURL is used to mark whether the right data is declared by the URL or directly stored in the descriptor.

-Scheme type box (SchemeTypeBox) and scheme information box (SchemeInformationBox)
The scheme type box identifies the protection scheme. A scheme information box is a container box that is interpreted only with the scheme in use. All the information required by the encryption system is stored here.

The scheme type box consists of the following fields.
-Scheme type (Scheme_type) is a code that defines a protection scheme.
-Scheme version (Scheme_version) is the version of the scheme used for content generation.
-Scheme URI (Scheme_URI) allows an option to guide the user to a web page if the scheme is not installed on the user's system. This is an absolute URI formed as a null terminated UTF8 character string.

  Additional scheme type boxes for other specific schemes are optional (eg, ISMACrypt and OMA DRM 2.0 PDCF) along with a scheme information box. If optional notifications are present, it means that a terminal capable of implementing these special DRM schemes (eg ISMACcrypt or OMA DRM 2.0 PDCF) will attempt to interpret the protected AVS-M file. The IPMP information defined above is mapped to such special scheme information.

  If an attempt is made to interpret a protected ISMA encrypted (ISMACrypt) file and / or an OMA DRM 2.0 PDCF file with a terminal (AVS-M file reader) that implements the IPMP information defined above, Before packaging into a protected AVS-M compliant file, all information reported in the scheme information box of the ISMACrypt file or scheme type box including OMA DRM 2.0 PDCF is mapped to the IPMP information box so that Special protection schemes are treated as specific IPMP tools and the corresponding information is treated as specific IPMP data.

  FIG. 7 shows a server procedure for generating a protected AVS-M file. Initially, the content server 701 uses the default encryption algorithm, key management system, and rights data related information 703, or using only a specific IPMP tool to represent some unknown DRM module and rights related information 702, the IPMP description You must create and format the children. The plurality of IPMP descriptors constructs an IPMP information box 704 and further forms a protection scheme information box 706 with original form box 705 information (ie, a four-character code “avsm” representing the original unconverted sample input coding name). The protection scheme information box further forms a video box 708 with sample description box information 707 (ie, a four character code “encv” indicating that the declared video sample is protected). Finally, the converted (eg encrypted) AVS-M video media data contained in the media data box 709 and the video box are packaged together with the file name “avs1” to form a protected AVS-M file 710. To be downloaded or streamed by end users.

  FIG. 8 shows a procedure of a terminal or device that plays back a protected AVS-M file downloaded or streamed from a server. When the terminal 801 downloads or streams the AVS-M file 802 from the server, the first step is to extract 4-character code information stored in the sample description box 805 of the AVS-M video box 804. . If “avsm” is detected, the actual AVS-M file is in an unprotected format, and the AVS-M video media data stored in the AVS-M data box 803 can be directly played by the terminal. If “encv” is detected, the actually received AVS-M video media data stored in the AVS-M data box 803 is in a converted (eg encrypted) format and cannot be directly played back. Thus, further steps are required to obtain the information stored in the protection scheme information box 806. When 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 uses these information to obtain the key, license Etc. and the unprotected AVS-M video data is decoded and reproduced. If only specific IPMP tool information and rights-related data 809 are obtained from the IPMP descriptor 807, the terminal executes the actual DRM module 810 (with a special IPMPID) downloaded from somewhere to obtain an unprotected AVS -Invert (eg, decode) the M video data for playback.

  The present invention can be applied to the application field of digital media files, in particular, notification of protection information that controls the generation, distribution, and use of AVS-M media files.

The figure which shows the structure of an unprotected AVS-M file. FIG. 3 illustrates a general ISO compliant file format protection scheme for a video track. The figure which shows the general structure of a to-be-protected AVS-M file. The figure which shows a protection scheme box in the state in which all the subordinate boxes were used for AVS-M file protection. The figure which shows the format of default IPMP descriptor with all the essential protection information (encryption and key management system related information). The figure which shows the format of the IPMP descriptor which stores rights relevant information. The figure which shows the procedure of the server which produces | generates a to-be-protected AVS-M file. The figure which shows the procedure of the terminal or apparatus which reproduces | regenerates the protected AVS-M file downloaded or streamed from the server.

Explanation of symbols

101 File type box 102 Movie box 103 AVS-M video track box 104 Media data box 105 Main brand indicator 106 Handler box 107 Sample description box 201 Media type 202 Protection scheme information box 203 Media data 301 4 Character code 302 Protection scheme Information box 303 Encrypted AVS-M data 401 Protection scheme information box 402 Original format box 403 IPMP information box 404 Scheme type box 405 Scheme information box 501 IPMP descriptor IDEx
502 IPMP tool ID
503 AES mode 504 IV length 505 Selective encryption 506 Key indicator length 507 Flag 601 IPMP tool ID
602 Control point 603 Flag 701 Content server 702 Rights related information 703 Rights data related information 704 IPMP information box 705 Original format box 706 Protection scheme information box 707 Sample description box information 708 Movie box 709 Media data box 710 Protected AVS-M file 801 Terminal 802 AVS-M file 803 AVS-M data box 804 AVS-M video box 805 Sample description box 806 Protection scheme information box 807 IPMP information box 808 Rights data related information 809 Rights related data 810 DRM module

Claims (11)

A method for protecting media files,
Generating DRM protection information in the IPMP descriptor and storing them in the IPMP information box in the file;
Generating an IPMP information box that includes a source format box within a protection scheme information box in the file;
Notifying further DRM protection information at the sample description box level in the file;
Including all the protection information necessary for the media data playback function to process the media data in the video box together with the media data box containing the converted media data to form a complete protected file structure. Method. Storing usage rights information in IPMP rights data;
Storing IPMP rights data as an IPMP data type in an IPMP descriptor;
The media file protection method of claim 1, further comprising: storing the IPMP descriptor in an IPMP information box in the file to indicate that accompanying media data is governed by a description usage rule.   The media file protection method according to claim 2, wherein the rights data is direct XML or binary rights information, or simply a URL for the terminal to track actual rights data. Storing the media-converted (eg encrypted) related information in an IPMP descriptor;
2. The method of claim 1, further comprising: storing the IPMP descriptor in an IPMP information box in a file to indicate that accompanying media data can be reconverted (eg, decrypted) using the description information. Media file protection method.   The media converted related information is general IPMP tool information including a defined IPMP tool ID and corresponding information for the user to download such a DRM module, or a specific default encryption algorithm and corresponding 5. The media file protection method according to claim 4, comprising any of key management system information.   The specific default encryption algorithm is preferably in AES CBC or AES CTR mode and the corresponding key management system information includes IV length, selective encryption, key indicator length, and actual key data information. The method of protecting a media file according to claim 5, wherein is not limited to this.   Preferably, the file is applied to an AVS-M video file and can be easily extended to protect AVS1.0 video, AVS1.0 audio, AVS-M audio, etc. The media file protection method described in the section.   8. The media file protection of claim 7, wherein the AVS-M video file has a 4-character code name “avs1” for a file brand and a 4-character code “avsm” for its original sample track input description. Method. A media file protection method comprising:
All the protection information for the media file stored in the IPMP information box is similarly mapped to the scheme type box and the scheme information box in the protection scheme information box, and this is mapped to other protected media types (for example, ISMACrypt). Or OMA DRM2.0 PDCF file),
Interpreting the mapped information and playing the protected media file with a terminal that implements only these special DRM schemes (eg, ISMACcrypt file and OMA DRM2.0 PDCF). A media file protection method comprising:
Map specific protection information declared in the scheme type box and scheme information box in the protection scheme information box of any protected media format (eg, ISMACrypt or OMA DRM2.0 PDCF file) to the IPMP descriptor in the IPMP information box Steps,
Interpreting the mapped information and playing the protected media file by a terminal that implements only the AVS-M standard protected file. The media file protection method according to claim 10, further comprising the step of specifying a special protection scheme (for example, ISMACrypt and OMA DRM2.0PDCF) as a specific IPMP tool, and corresponding information as specific IPMP data.

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