JP2010123247A - Obscuring data in an audiovisual product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for creating and/or reproducing an audio visual product. <P>SOLUTION: Access to an audio visual product (400) is controlled by concealing data. Cells of audio visual data (400) A, B, and C are reproduced by a sequence instruction (410) (e.g., a PGC or Program Chain). One sequence instruction (410a) correctly reproduces the cells of the audio visual data (400) A, B, and C, but is hidden among many other sequence instructions (410b) which incorrectly reproduce the sequence of cells (e.g., BAC, ACB, and CAB). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention generally relates to a method and apparatus for use in the production or playback of audiovisual products. In particular, the present invention relates to a method and apparatus for use in controlling access to an audiovisual product by hiding data in the audiovisual product.

  It is desirable to control access to audiovisual products. In particular, it is desirable to limit opportunities that exist at the present time to browse or access audiovisual content without authentication.

  In general, audiovisual content, such as movies or other displays, is formed by collecting many small sections or clips of raw audio and visual content. This is usually referred to as the “authoring” process, where raw sound clips and video clips are gradually assembled and edited together to form a finished audiovisual product. Next, the audiovisual product is recorded on a certain type of recording medium. Conventionally, this medium is an analog medium such as celluloid film or analog video tape (eg VHS format video tape). More recently, it has become possible to record audiovisual content on random access media, including optical disc media such as DVDs in particular, or other forms of random storage such as magnetic hard drives. These random access media have many advantages in terms of size, data capacity, playback speed, image quality, and the like. However, it has also been recognized that there are disadvantages that it is relatively easy to browse or access stored audiovisual products without being authenticated.

An optical disc is a convenient recording medium for many different purposes. Digital versatile discs (DVDs) have been developed to have capacities of up to 4.7 Gb for single-sided (single-layer) discs and up to 17 Gb for double-sided (dual-layer) discs. There are currently several different formats for recording data on DVD discs including DVD video discs, DVD audio discs, and DVD RAM discs, among others. Of these discs, DVD video is specifically designed to be used for pre-recorded video content such as moving images. Due to its large recording capacity and ease of use, DVD disks have become widely used and are commercially important. Conveniently, DVD video discs are played back using dedicated playback equipment with relatively simple user control, and DVD playback devices that play back DVD video discs are becoming more widespread. is there. More detailed background information on the DVD video standard can be found at www. dvdform. available from the DVD forum at org or any other site.

The DVD video standard includes many built-in copy protection functions to protect the audiovisual data content of the disc. These copy protection functions include Content Scrambling System (CSS) and Macrovision Copy Protection, which encrypts audio video data blocks using a content scrambling system. Data is prevented from being played separately from the DVD video display, and macrovision copy protection is used to prevent video copying using the recording device. Both of these systems are interpreted by a DVD video playback device that performs the appropriate functions during playback. These approaches are effective to protect the data content for the average consumer, but are skilled in the technology of creating and producing a copy of a disk or part of a disk. "engineer") can easily break both systems.

  A problem has been recognized that the DVD video standard does not include a built-in function that allows content to be securely held on a disc while keeping it out of the reach of very good reverse engineers. As an example to illustrate this problem, an operation such as inputting a specific key combination on a DVD video disc (for example, pressing a “left arrow” key within 5 seconds after a certain menu appears) ), So-called “Easter Eggs”, which are invisible data on the disc. A reverse engineer can easily access such content by simply extracting the relevant audio-video object directly from the disc without knowledge of the key combination. Many audio video survey software packages are available, and these software packages can be used to “rip” each individual video display on the disc. For example, in this regard, inter alia www. dvd-ripper. com.

  U.S. Pat. No. 6,161,179 (WEA Manufacturing, Inc.) discloses a method of protecting a light readable disc with a key, which The disc player supplies a unique key every time a disc is played. The user sends a unique key to the transaction service and receives an unlock key as a reply. The user transmits an unlock key to the disc player. Then, the disc player confirms that the unlock key and the unique key have a predetermined relationship before disc playback. This known protection method allows video pay-per-view or other pay-per-use of audiovisual products delivered to optically readable discs, as in the DVD video format. Commercialization is possible.

  There are a wide range of applications where the level of security and protection exceeds that achieved by known copy protection protection approaches and needs to be higher. These problems arise not only in connection with DVD video format optical discs, but particularly in many other environments where audiovisual content is recorded on random access recording media.

  One object of the present invention is to provide a method and apparatus for use in the production and / or playback of an audiovisual product, at least in certain preferred embodiments of the present invention, by means of these methods and apparatus. User access to visual products is restricted. In particular, one object of the present invention is to restrict copying, viewing, or other unauthorized access to audiovisual products.

  One object of at least some embodiments of the present invention is to provide methods and apparatus for use in the production and / or playback of audiovisual products, by means of these methods and apparatus, which are technically savvy reverse engineers. Even so, you will encounter a huge obstacle that prevents free and unrestricted access to audiovisual products.

According to the present invention there is provided an apparatus and method as set forth in the appended claims. Preferred features of the present invention will become apparent from the appended claims and the following description.
In general, an audiovisual product suitable for the present invention has a plurality of cells of audiovisual data, and the reproduction of the audiovisual data is controlled by one or more sequence instructions. Preferably, each of these cells and each of these sequence instructions has a predetermined structural location within the audiovisual product, depending on the structural location, from cell to cell, or from one sequence instruction to another sequence instruction. It is possible to move using navigation within an audiovisual product.

One aspect of the invention relates to a method of using an access code that controls access to an audiovisual product as a form of unlocking process.
In one exemplary aspect of the present invention, a method is provided for use in generating an audiovisual product, the method comprising receiving original audiovisual data played according to an original content sequence; Dividing the visual data into a plurality of cells and generating a plurality of sequence instructions, each sequence instruction representing a playback sequence in which the cells are played in a specified order; and a plurality of steps Assigning each sequence instruction to one of the plurality of structure locations in the audiovisual product and operating on the access code to calculate a destination structure location from the plurality of structure locations , Multiple sequence instructions And generating a destination function of selecting one of the sequence instruction from within.

  In another exemplary aspect of the present invention, a method is provided for use in playing an audiovisual product, the method receiving an access code, accessing a destination structure location in the audiovisual product, and accessing a destination function. Calculating by applying to the code; and selecting a sequence instruction corresponding to the location by jumping to the calculated destination structure location.

  In use, the destination structure location within the audiovisual product is calculated by applying the destination function to the received access code. By jumping to the calculated destination structure location, the sequence instruction corresponding to that location is selected. As a result, the selected sequence instruction initiates playback of a sequence of cells of audiovisual data within the audiovisual product.

  Preferably, the access code is entered during playback of the audiovisual product. Most preferably, the access code is entered by the user using an input device such as a keypad or remote control unit or other communication device. As an example, the access code is a numeric code (eg, 1234) that is entered through an image display on a numeric keypad.

  Preferably, the destination function applied to the access code is a mathematical function that returns a numeric value representing the destination structure location in the received access code. The access code can take any suitable form, but preferably contains a numeric value within a predetermined range, and when the destination function is applied to the numeric value of the access code, the structure of the correct sequence instruction by the destination function Since the location is calculated, protected audiovisual data such as an "Easter Egg" function or a section of a movie can be obtained. On the other hand, applying the destination function to an illegal value will generate some other structural location. For example, the destination function generates a structural location that causes, for example, the message “Access is denied” or an illegal sequence instruction is generated by this structural location and an illegal sequence instruction. As a result, audio visual data cannot be reproduced safely.

  The destination function preferably includes a one-way hash function. Preferably, the destination function operates with at least two access codes each having a numerical value. Preferably, the destination function is applied to generate a first access code, display it to the user, and operate with a second access code sent as a reply. A seed is generated by the destination function and a transformation is applied to generate a first access code so that the seed of the first access code is not revealed to the user.

  This aspect of the invention can be embodied in many different specific configurations, which can be achieved by having the access code associated with the destination function to unlock the audiovisual content and allow the user to enjoy the content. It is done according to the method that can be. This unlocking method is particularly useful to prevent free and unrestricted access to audiovisual products by regular consumers. That is, most regular consumers only have access to the audiovisual product, or a selectively locked section of the audiovisual product, once they have the correct unlock access code.

Another aspect of the invention relates to hiding data in an audiovisual product.
In one exemplary embodiment, the present invention provides a method for use in generating an audiovisual product, the method comprising receiving original audiovisual data played according to an original content sequence; Dividing the audiovisual data into a plurality of cells, and generating a plurality of sequence instructions, wherein each sequence instruction represents a playback sequence for reproducing these cells in a specified order; and The plurality of sequence instructions includes at least one correct sequence instruction for reproducing the original content sequence by the reproduction sequence, and a plurality of illegal sequence instructions for not reproducing the original content sequence by the reproduction sequence.

  In another exemplary embodiment, the present invention provides a method for use in playback of an audiovisual product, the method comprising receiving an audiovisual product, wherein the plurality of sequence instructions is an audiovisual product. Receiving an audiovisual product, comprising: at least one correct sequence instruction for playing the audiovisual product according to the original play sequence; and a plurality of illegal sequence instructions that do not play the audiovisual product according to the original play sequence; Selecting one sequence instruction from among the sequence instructions; and reproducing the audiovisual data of the cell according to the selected sequence instruction.

This aspect of the invention provides a simple but effective mechanism for controlling access to original audiovisual data contained in an audiovisual product. The original content is divided into a plurality of cells, and these cells are reproduced in order according to the reproduction sequence command. One or more correct sequence instructions that allow the reconstruction of the original content sequence from multiple cells are themselves hidden within multiple illegal sequence instructions. Advantageously, a relatively large number of sequence instructions are generated, in which case a relatively small number (eg 1 or 2) of sequence instructions reproduces the cells correctly and reconstructs the original content sequence. . Preferably, each of the remaining large number of illegal sequence instructions prevents the audiovisual product from being successfully played out of the group of cells. By obfuscating the correct sequence instructions in this way, access to the original audiovisual data can be controlled safely and reliably. Only users who can select the correct sequence instructions can obtain the original audiovisual data.

  Preferably, the plurality of sequence instructions are formed as a plurality of permutation sequences, where only one such permutation sequence corresponds to the original content sequence. The audiovisual data of the cell is reproduced by each of the other plurality of order changing sequences, but the reproduction according to the original content sequence is not performed. Accordingly, since each of the plurality of sequence instructions is reasonably similar to each other, it is relatively difficult for the reverse engineer to determine which sequence instruction is correct. As a result, the correct sequence instruction is buried in an illegal sequence instruction in which a plurality of orders are changed, and it becomes difficult to read out the correct sequence instruction.

  In one preferred embodiment of the present invention, a plurality of cells are arranged in a sequence other than the original content sequence. That is, these cells are rearranged to provide a new, congested cell sequence that conceals the original audiovisual data. Recording these cells in a crowded sequence means that the reverse engineer cannot easily regenerate the original audiovisual data from the cells. In order to correctly reproduce the original content sequence, it is also necessary to recognize the correct sequence command.

One aspect of the invention relates to adding one or more erroneous “spoofed” cells that are not originally included in the original content sequence.
In one exemplary embodiment, the present invention provides a method for use in generating an audiovisual product, the method comprising receiving original audiovisual data played according to an original content sequence; Dividing the audiovisual data of the plurality of cells into cells of correct audiovisual data, adding at least one error cell containing erroneous audiovisual data to the cells, and selecting a selected of the cells Forming at least one sequence command representing a playback sequence for playing back cells in a specified order.

  In another exemplary embodiment, the invention provides a method for use in playing an audiovisual product, the method comprising receiving an audiovisual product having audiovisual data divided into a plurality of cells. A plurality of cells selected from among the plurality of cells, at least one correct cell including correct audiovisual data unique to the original content sequence, at least one error cell including erroneous audiovisual data; Receiving an audiovisual product including at least one sequence instruction representing a playback sequence for playing back the cells in a specified order, and playing back the audiovisual data of the cell according to the sequence instructions.

  Preferably, an erroneous red herring cell contains a short section of the original audiovisual data and initially appears as originally contained in the original content sequence, but the audiovisual data is, for example, The video data is altered by playing it in the reverse direction. Therefore, when an error camouflaged cell is reproduced, the original content sequence cannot be viewed correctly. Other examples of error cells include, among others, inverted images, high or low contrast images, snow, fading, jitter, and overly loud, soft audio or distorted audio A disturbing visual or audio effect.

Yet another aspect of the invention relates to a method of using a scrambled video stream in an audiovisual product.
In one exemplary embodiment of the present invention, a method for use in generating an audiovisual product is provided, the method comprising receiving original audiovisual data played according to an original content sequence; Dividing the audiovisual data into a plurality of cells; assigning the cells to these video streams such that the plurality of cells are included in at least the first video stream and the second video stream; Switching to a second video stream and generating a video stream switching instruction to play these cells according to the original content sequence.

  In another exemplary embodiment of the present invention, a method is provided for use in playing an audiovisual product, the method comprising a plurality of cells consisting of audiovisual data and together representing the original content sequence. Receiving an audiovisual product, wherein the cells are divided into at least first and second video streams, executing the audiovisual product, and executing one or more video stream switching instructions; Automatically switching between at least the first video stream and the second video stream during playback of the cell and playing back the audiovisual data according to the original content sequence.

  The original audiovisual data to be played according to the original content sequence is divided into a plurality of cells, and these cells are divided into these video streams so that these cells are included in at least the first and second video streams. A video stream switching instruction is used to automatically switch between the first video stream and the second video stream to play these cells according to the original content sequence.

  Preferably, the video object holds each cell, and a video stream switching instruction determines a video stream to be played as either the first video stream or the second video stream from the video object. The error data is ideally recorded in another stream. Since at least one preliminary video object has a program command for executing a video switching command to select either the first video stream or the second video stream, the multi-angle video object corresponds to a cell. Hold in the video stream. Preliminary video objects and multi-angle video objects are appropriately interleaved. That is, one or more preliminary video objects are played in order, followed by one or more multi-angle video objects, and this procedure is then repeated. The video stream switching command is preferably executed using a forced activation button command connected to the hidden menu button. The button command appropriately selects from the DVD video virtual command set to set the video stream special parameters (ie SPRM3) to the desired video stream suitable for the next multi-angle video object.

  Preferably, a sequence generator is used to generate the video stream sequence in sequence. The sequence generator is preferably a deterministic algorithm generated using one or more initial parameters as a seed. In one preferred embodiment, one or more initial parameters of the plurality of initial parameters are re-supplied upon playback as a type of key.

  The preferred embodiment of the present invention relates to an audiovisual product that can be played in particular according to the DVD video standard. Preferably, the sequence instructions are executed as a program chain (PGC). In addition to effectively controlling access to audiovisual data contained in DVD-Video products, it is desirable to maintain efficient use of available storage capacity of recording media such as optical disks. Most of the data of a normal DVD video disc is occupied by audio video display data contained within cells and video objects (VOBs). Unlike this, the storage capacity occupied by navigation data such as programs (PGs) and program chains (PGCs) is relatively small.

  Each of the embodiments of the invention described herein can be used alone. Suitably, any two or more of the embodiments of the present invention may be used in combination. Most preferably, the locking, obfuscation, and content scrambling forms described herein can all be used in combination.

  In one particularly preferred embodiment of the invention, the original content sequence is divided into a plurality of cells, and these cells and / or video streams are scrambled. Therefore, it is difficult to reconstruct the original content sequence by simply reading the audiovisual object of the audiovisual product. Furthermore, the correct sequence instructions are buried and hidden among many similar illegal sequence instructions. Furthermore, access to the correct sequence instruction is controlled by the destination function and access code. As a result, a very high level of security is obtained with respect to the original audiovisual data contained in the audiovisual product.

  The present invention is also defined herein as an audiovisual product formed by or adapted to be used in any of the aspects of the present invention. Can be extended. The audiovisual product is preferably a DVD video product, in particular an optical disc on which audiovisual content is recorded in accordance with the DVD video standard.

  Conveniently, in at least some preferred embodiments, the present invention is implemented as a computer program or a series of computer programs. The program or programs can be recorded on any suitable recording medium, including an erasable storage medium such as a magnetic disk, hard disk, or solid state memory card, or recorded as a modulated signal on a carrier wave It is transmitted over either a local area network (LAN) or a suitable data network such as a wide area network (WAN) such as the Internet.

  In at least some preferred embodiments, the present invention is suitably implemented on a computing platform, ideally a general purpose computing platform such as a personal computer, or in a client-server computing network. Alternatively, the present invention is implemented in whole or at least in part by dedicated hardware. For example, the present invention is implemented in a recreational household appliance such as an optical disk playback device or recorder. In at least some preferred embodiments, the present invention is implemented in a DVD video playback device that plays back an optical disc in DVD video format, or in a DVD recorder that records DVD video format data on an optical disc.

1 is a schematic diagram of an apparatus for generating an audiovisual product for use in a preferred embodiment of the present invention. It is a schematic diagram of the reproducing | regenerating apparatus which reproduces | regenerates the audio visual product used for preferable embodiment of this invention. FIG. 3 is a schematic diagram of an optical disc recording medium and data recorded on the recording medium according to a preferred embodiment of the present invention. It is a schematic diagram which shows the mode of order change of PGC used for suitable embodiment of this invention. FIG. 2 is a flow schematic diagram of a preferred method of generating an audiovisual product. FIG. 6 is a flow schematic diagram of a preferred method for playing an audiovisual product. FIG. 3 is a schematic diagram of an exemplary original audiovisual clip. The identification information of the scene cut in an audio visual clip is shown. Audio visual clips subdivided into each scene. An audiovisual clip divided into each cell is shown. Fig. 2 shows a camouflaged cell inserted into a plurality of cells. A plurality of crowded cells are shown. Indicates reassignment of reference numbers to multiple cells. An exemplary correct playback sequence command is shown. The navigation program with the correct playback sequence command is shown. The navigation program of an illegal reproduction sequence command is shown. One correct playback sequence command buried within many illegal playback sequence commands is shown. FIG. 2 is a schematic diagram illustrating a preferred content scrambling method using a video stream. It is a schematic diagram of content data divided into a plurality of cells and allocated to a plurality of video streams. It is a schematic diagram of the video object used for the suitable content scramble method. 4 is a table of exemplary sequence generation functions. It is an example of a DVD virtual command used for executing video stream switching. It is another schematic diagram of content data divided into a plurality of cells and allocated to a plurality of video streams.

For a more complete understanding of the present invention and to illustrate how embodiments of the present invention can be implemented, reference is made to the accompanying schematic drawings as an example.
A preferred embodiment of the present invention will be described with reference to a specific example of a DVD video format optical disc containing audiovisual content. However, it should be understood that the present invention is particularly applicable to a wide range of other environments where audiovisual content is stored on some form of random access storage media. Also, the DVD video format itself will eventually be replaced and replaced by a new format definition. That is, it is considered that the present invention can be applied in an environment that has not been realized yet in the future.

  FIG. 1 shows an example of an authoring apparatus that can be used in a preferred embodiment of the present invention. In this embodiment, the authoring device includes a computing platform such as a client server computer system or a stand-alone personal computer 30. Optionally, raw audio and video data is received through camera 10 and microphone 20, etc., or supplied from other sources such as file storage device 25, or authored by image and sound generation software, etc. Generated inside the device. Raw content data can include video clips, audio clips, still shot images, icons, button images, and other visual content displayed on-screen. The content is suitably in MPEG or JPEG encoded file format, but can be in any format.

  This original audiovisual data can be in any form, such as a movie or company presentation, or a quiz game, among many other possible forms. The personal computer 30 functioning as the authoring device generates the desired audiovisual product as will be described in more detail below. The authoring device 30 writes the audiovisual product 400 to a storage medium such as a hard disk inside the personal computer 30 or to the optical disc 40.

  FIG. 2 is an overall schematic diagram of an apparatus for playing an audiovisual product 400 that can be used in a preferred embodiment of the present invention. In this example, the audio visual product 400 of the optical disc 40 is input to a playback device including the DVD playback device 50 and the television screen 60. Control by the user is performed through the remote control handset 70 or the like. As described in further detail below, in one exemplary embodiment, audiovisual product 400 is controlled by the user entering an access code or PIN code 80. As shown in FIG. 2, the access code 80 is displayed on the television screen 60 in response to a user input through the remote control device 70.

  FIG. 3 shows details of the structure of the audiovisual product 400. In this example, the audio visual product 400 includes cells AV1, AV2,. . . It includes a plurality of cells 420 represented by AVm. Each cell 420 contains a short section of audiovisual data. These cells are normally played back one after the other to provide the desired audiovisual display under control of the play sequence command 410. The sequence instruction 410 shown in FIG. 3 is different from these cells 420. Appropriately, cells 420 and sequence instructions 410 are each assigned to a structural location within the audiovisual product to allow navigation between these instructions 410 and navigation from instruction 410 to cell 420.

  In the preferred example of DVD video format data, the cell group 420 is played back continuously by incorporating the cell group into a plurality of programs (PGs) by reference to these cells, which in turn is It is organized into program chains (PGCs). In FIG. 3, the sequence instruction 410 includes program chains PGC1, PGC2,. . . It is represented by PGCn. Preferably, each cell 420 includes at least one video stream, at least one audio stream, and / or at least one sub-picture stream.

  The DVD video format allows a many-to-one mapping from program chain groups (PGCs) to cells, which mapping is first incorporated into the standard to support multiple storylines. An example of this is a DVD video disc, which includes two separate late versions of the same movie, corresponding to a program (PG) version and a general (G) version, a general version Some scenes have been removed. When a viewer plays a disc, he or she can start by selecting whether to play the program (PG) version or the general (G) version, and the “parental control” on the DVD. The function can be reliably utilized for this purpose. Normally, most parts of movie content are common to both program (PG) or general (G) versions and are recorded only once on the disc. However, the program chain (PGC) related to the program (PG) version omits selected scenes included only in the program chain (PGC) related to the general (G) version, or vice versa.

  Most of the data of a normal DVD video disk is occupied by the audio video display data included in the cell group 420, and the storage capacity occupied by the display data including the program chain (PGC) 410 is relatively small. The present invention uses several variations of the method of reproducing these cells 420 without duplicating the audio video data.

[Obfuscation of sequence instructions]
In a first aspect, the present invention provides an audiovisual product that conceals and hides the correct playback sequence instructions in many illegal sequence instructions.

  The preferred embodiment of the present invention uses a plurality of program chains (PGCs) 410 to refer to the lower cell group 420 in a plurality of different sequences, so that only one of these sequences is correct. By configuring, obfuscation is realized.

  For example, for three cells A, B, and C, six program chains (PGC) 1-6 can be defined as shown in FIG. In this case, there are six usable content playback sequences, and only PGC1 provides the correct sequence among these sequences. Therefore, PGC1 is a correct sequence instruction 410a, and the other PGCs 2 to 6 are all illegal sequence instructions 410b. This approach can be taken to hide the correct video sequence. For this purpose, the duration of the cell group 420 needs to be very short (a single cell can contain audio / video for a short duration of 0.4 seconds) and a video program can contain many cells. It is necessary to divide into 420. In the DVD video standard, a PGC can include a maximum of 256 cells, and a video title set (Video Title Set: VTS) that is the entire structure of the PGC includes a maximum of 32767 PGCs. Can do. Therefore, one cell can be shared only by 32767 PGCs at the maximum. In the above example, the correct sequence A, B, C consists of a group of consecutive cells 420 that are played back sequentially.

  FIG. 5 outlines a preferred method for generating an audiovisual product. Raw audiovisual data is received at step 510. In step 520, the audiovisual data is divided into cell groups 420 as outlined above with reference to FIG. 4 and described in more detail below. Step 520 can include step 521, in which an error cell is added to the original audiovisual data. Step 520 can also optionally include step 522, in which cell group 420 is scrambled (rearranged or congested) so that these cells are restored to their original desired reproduction. Don't support sequences.

  In step 530, a plurality of sequence commands 410 are generated, and the playback sequence of the cell group 420 generated in step 520 is controlled by these commands. Step 530 includes step 531 in which one or more correct sequence instructions 410a are generated and the correct sequence instructions are interspersed with other illegal sequence instructions 410b. In step 532, the order of correct sequence instructions 410a is optionally changed to generate more illegal sequence instructions 410b, and one or more correct sequence instructions 410a are generated by such processing. It hides in many illegal sequence instructions 410b.

  Once the cell group of audiovisual data and the corresponding sequence instructions 410 have been generated in steps 520 and 530, in step 540, the audiovisual product is formatted and recorded on an appropriate storage medium. In a preferred embodiment, the audiovisual product is formatted according to the DVD video standard and recorded on a hard disk drive or preferably an optical disc. This step 540 can optionally include downstream processing steps, in which, for example, structural locations are assigned to cells 410 and sequence instructions 420 and recorded or burned to an optical disc. Generate a ready-made explicit disc image (ie a bitstream image).

FIG. 6 is a schematic diagram of a preferred method for playing an audiovisual product 400.
In step 610, a generated audiovisual product 400 that includes a group of cells 420 of audiovisual data and a plurality of playback sequence instructions 410 is received.

  In step 620, one of these playback sequence instructions 410 is selected. Step 620 preferably includes performing an authentication process to confirm that the user has permission to play the audiovisual product. In one embodiment, the authentication process includes step 621 in which user input such as a user access code or PIN is received, in step 622 the structural location within the audiovisual product is calculated, and the steps In 623, jump to the calculated location. Such a calculation in step 622 appropriately provides one structural location corresponding to one of the playback sequence instructions. If the calculation in step 622 is correctly performed, the position of the correct reproduction sequence instruction 410a is specified. If the calculation is not performed correctly, one of many illegal reproduction sequence instructions 410b will be selected.

  In step 630, the audiovisual data of the cell group 420 is reproduced according to the selected reproduction sequence command 410. In step 630, the audiovisual data of the reference cell group 420 is retrieved from a storage medium such as an optical disc as appropriate, the appropriate decoding is performed, and the decoded data is summarized above, for example with reference to FIG. As described above, the data is output through the display screen and through the audio speaker.

[PGC obfuscation]
Next, a particularly preferred embodiment of the present invention will be described by showing further examples with reference to FIGS.

  FIG. 7 shows an exemplary audio video clip 700. Assume that the source video content that needs to be protected consists of a 60-second clip that contains three “cuts” so that the clip contains four different scenes. It should be noted here that scene cut points are usually provided implicitly within a clip, rather than being given as four separate sub-clips.

It is desirable that the sequence is divided into cell groups 420, each cell having an average period of 3 seconds, resulting in a total of 20 cells constituting the sequence.
The provided video clip is searched for scene cuts. There are known methods used for this purpose based on the discontinuity of the video stream and / or audio stream. For example, G. Acribus, N. Duramis, A. Duramis, S. Proceedings of MELECON 2000 MedicaneousNeconomic Contechnical Contechnical, 2000, entitled “Scene Detection Method of MPEG-encoded Video Signals” by G. Akrivas, N. Doulamis, A. Doulamis, and S. Kollias. I want. As shown in FIG. 8, the scene cut becomes an anchor point for performing subdivision later.

  As shown in FIG. 9, in this example, the clip is divided into cell groups 420 each having a period of about 3 seconds, and the cell group 420 is fixed to a cut scene point. By slightly changing the period of the cell group 420, the resulting cell group does not have a uniform period.

[Error “red herring” cells]
According to FIG. 10, it is advantageous to incorporate error “spoof” cells 421 that are not referenced into the correct playback sequence 410a. ("Red herring" is literally a disturbance to distract attention, and it is derived from using a fish (smoked herring) to disturb the hound so that no trace of odor can be identified. Such an error cell group 421 means that these error cells look very similar to the correct cell group 420 and easily remove all the sequence instructions including the obviously inappropriate cell group 421. Properly configured to prevent For example, if the product includes a series of cells with each cell having a period of 4 seconds:

Cell 1--starts at 0 seconds and ends in 4 seconds cell 2--4 starts at seconds and ends at 8 seconds cell 3--starts at 8 seconds and ends at 12 seconds In this case, as an example The error cell group of
Impersonation 1-2-Starts from 2 seconds and ends in 6 seconds Impersonation 2--Starts from 6-6 seconds and ends in 10 seconds Actually, the duration of each cell is obviously wrong, for example using time code search method The cell group is changed so that a pattern that can be discarded from the pattern is not generated.

  As shown in FIG. 10, a number of erroneous “spoofed” cell groups 421 are generated, and these cells have similar lengths as the other cell groups 420. The protection level increases with the number of error camouflaged cells 421 and is usually limited by the available storage capacity of the disk. In this example, it is assumed that 20% error camouflaged cell groups are provided. These error-spoofing cells 421 ideally start at and end at points that are not shared by other valid cell groups or are not scene cut points. The error forged cell group 421 is indicated by a hatched box in FIG.

As shown in FIG. 11, the error-forged cell group 421 is inserted into the reproduction order of the effective cell group 420 starting from the cell start time.
[Cell scrambling]
As shown in FIG. 12, the cell group 420 (including all error cells 421) is crowded by changing the location of each cell with respect to other cell groups, so the order in which the cell groups 421 are displayed on the disk. Is determined. The cell group 420 can be crowded in any way, but this configuration is high level if each available playback sequence meets the constraints detailed in the DVD video standard related to seamless playback. Will be protected. That is, seamless playback is performed--no playback skip--when there are two cells 420, the data associated with these cells must be relatively close together on the disk. Actually, since the cell group 420 can be reproduced seamlessly even when many sectors are separated from each other, in this example, the cell group 420 can be arbitrarily arranged continuously. Therefore, it is assumed that any cell needs to be located inside three cells 420 from the correct position of the cell.

  In the preferred DVD video format, cells 420 are numbered starting from 1 in the order in which they appear on the disc. Therefore, the crowded cell group 420 is continuously renamed in the order in which these cells appear on the disk, as shown in FIG. 13, using the underlined number indicating the renamed cell identifier. It is.

FIG. 14 shows a correct reproduction sequence in the illustrated arrangement.
Note that cells 4, 8, 15, and 19 are error-spoofed cells and do not occur in the correct playback sequence.

1, 2,. . . Based on the list of cell groups 420 set as 24, a number of incorrect playback sequences 410b are generated, each playback sequence selecting any 20 cells out of 24 cells, and these cells Are displayed in a random order. Again, the protection level is high if all such sequences meet the requirements for DVD video standards for seamless playback. If the sequence is broken down into N cells 420 and R error-forged cells 421 are added, the number of available sequences (ignoring restrictions on seamless playback) is (N + R)! / R! It becomes. In this example, this number is 24! / 4! be equivalent to. This number is very large (2.6 × 10 ²² ), and in practice the number of available sequences displayed on the disc is limited by the DVD video limit on the number of program chains (PGC). Since audio / video data is shared among a plurality of program chains (PGC), the playback sequence is actually limited to 32,767. Since each playback sequence is stored with reference to the playback cell group 420, each of these sequences can be displayed on a DVD disc using very little data.

  Each of these playback sequences 410 (ie, a correct sequence 410a that is a combination of multiple incorrect sequences 410b) is displayed using a program (PG) DVD video navigation structure. The navigation structure consists of a list of cell pointers. A plurality of programs are stored inside the program chain structure. The program corresponding to the correct sequence 410a in this operation example can be structured as shown in FIG.

Playback sequences 1, 2,. . . An example of one illegal sequence 410b consisting of 20 is shown in FIG.
A program chain is generated for each playback sequence group within one video title set (VTS). Assume that a total of 1,000 sequences are generated for the disc, one of these sequences is a correct sequence and 999 are incorrect sequences. One of the plurality of sequence commands 410a has a sequence command serving as a destination for unlocking the video, in this example, a sequence including correctly arranged cells 420 as shown in FIG. The PGC number 321 including the program is selected.

  The audiovisual product is then ready to be recorded on a suitable storage medium, in this example an optical disc. However, yet another intermediate authoring step is performed to convert the edited audiovisual product to a specific version, i.e. a disc image ready to be burned onto a blank, previously unrecorded optical disc. To do.

  In order to extract the correct sequence of cells 420, the reverse engineer needs to analyze all possible combinations. Assuming that the maximum number of available cell groups 420 are encoded, a reverse engineer can view up to 32,767 hours (3.74 years) of content to reconstruct the one hour program. It will be necessary to do.

  When preparing multiple sections of video, it is preferable to ensure that there is no clear clue to the correct sequence of cells 420. For example, all MPEG elementary stream time codes are erased so that this information cannot be used to arrange a series of cells 420 in the required order. In addition, the cell group 420 is divided at a plurality of scene boundaries, so that the reverse engineer cannot easily compare the last frame of one cell with the first frame of another cell to infer the correct playback sequence. It is necessary to.

  To solve the problem of limitations on the number of program chains (PGCs) per video title set (VTS), the method outlined above has been extended to use multiple video title sets (VTS) The playback sequence can be found by increasing the number of destination sequence instructions that need to be performed. In this case, the video program is divided into equal periods of v sections, section 1 is mapped to video title set (VTS) 1 and the last section v is mapped to video title set (VTS) v. Within each video title set (VTS), up to 32767 program chains (PGCs) can be used to obfuscate the program, ensuring that the correct PGCs for each VTS are unrelated, and for each correct PGC individually Reach through calculation.

  In the reproduction of an audiovisual product, a correct reproduction sequence command is obtained from many illegal reproduction sequence commands 410. In the above example shown in FIG. 17, this requires PGC 321 as the correct playback sequence instruction 410a to satisfy the audiovisual content in a satisfactory manner, ie according to the cell sequence shown in FIG. Then, it means that the cell 2 can be reproduced by reproducing the cell. As will be apparent to those skilled in the art, various options can be utilized to determine whether a user is authorized to access audiovisual content. For example, a physical token such as a smart card is presented to a card reader or some form of biometric authentication (eg, fingerprint authentication) is performed. The playback device is then instructed to operate according to the correct playback sequence command, which is suitably done by jumping to the structural location associated with the correct playback sequence command.

[Scramble video stream]
Yet another aspect of the present invention relates to scrambling video objects in an audiovisual product to make it more difficult for unauthorized access or unauthorized copying to the audiovisual product.

The preferred embodiment relates to an audiovisual product that can be played back according to the DVD video standard, and is described in detail below.
The DVD video standard provides a structure that holds an audiovisual data stream and is known as a Video Object (VOB). The video object (VOB) is internally divided into cell groups, as also schematically described above with reference to FIG. An audiovisual program is displayed by playing a series of video objects (VOB) in a predetermined sequence using a program and a program chain (PGC). In the current DVD video standard, a video object (VOB) has 1 to 9 video streams (often referred to as “multi-angle” streams), 0 to 8 multi-channel audio streams, and 0. Contains ~ 32 sub-picture streams.

  These objects can be ordered so that successive video objects (VOBs) contain different numbers of streams. For example, the first VOB may include one video stream, and the second VOB may include four video streams. VOBs containing multiple video streams are often referred to as “multi-angle blocks”. A specific parameter (SPRM)-number 3 (SPRM3)-is used to define which video stream to play. When an audiovisual product is recorded with this specific parameter SPRM3 set to the value “4”, angle 4 is selected and played when the subsequent multi-angle stream continues. This feature is configured to allow the viewer to select from up to nine different camera angles and then browse the recorded video stream for the selected camera angle. However, the present invention uses this camera angle video stream function to improve the ability to protect audiovisual products and prevent copying or unauthorized access to the audiovisual products.

  FIG. 18 is an overview of a preferred method for scrambling the content of an audiovisual product using a video stream. Original audiovisual data, such as MPEG encoded audio data and / or video data, is received at step 1810. The original audiovisual data 401 is divided into cell groups 420 at step 1820. The cell group 420 is distributed in a plurality of video streams in step 1830. That is, not all the cell groups remain inside one video stream, but the cell groups are distributed inside at least two different video streams. Also, at least one video stream switch instruction is generated, and this instruction automatically switches from the first video stream to the second video stream during playback of the audiovisual product. In step 1830, a sequence command 410 is generated, and the playback sequence of the cell group 420 is controlled by this command. Next, in step 1840, the audiovisual product is formatted and recorded on an appropriate storage medium.

Next, this method will be described in more detail with reference to FIGS.
As shown in FIG. 19, the original audiovisual data 401 having a desired playback sequence (for example, a substantially linear story line) is processed in the same manner as described above with reference to FIGS. Divide into a plurality of cells 420. In this example, there are four cells with A, B, C, and D symbols. These cells are divided into different video streams. That is, some of the cell groups (A, B, and D) are assigned to the first video stream 1901 and at least one cell (C) is assigned to a different second video stream 1902. In order to reproduce the cell group 402 in a desired sequence (ABCD), a video stream switch is required between the first video stream 1901 and the second video stream 1902. If the first video stream 1901 is simply continued, a desired playback sequence cannot be obtained. In this example, if the first video stream 1901 is simply continued, the reproduction of the cell C is not performed. A video stream switch for capturing the cell C is represented by a thick arrow in FIG.

  FIG. 20 shows in detail how a video stream is used inside a video object (VOB). Conveniently, the cell group 420 is contained within a video object (VOB). Some of the cells (A, B, D) are held inside a simple video object (VOB) 2010 that has only one video stream. However, at least one video object 2020 is defined as having a plurality of video streams 1901,1902. The second video stream 1902 is set by forming such a multi-stream video object (multi-angle block). Cell C is held in the second video stream 1902 inside the multi-angle block 1920.

  In FIG. 20, cell C is inserted into both video streams 1901 and 1902 as C1 and C2. This makes copying more difficult. The reason is that both streams 1901 and 1902 clearly contain valid data. Cell C2 is preferably an error “spoofed” cell containing altered or defective video data. When the cell C2 is reproduced (that is, the first video stream 1901 is continued), the original audiovisual data 401 is not reproduced safely. Up to nine separate video streams can be set inside each multi-angle block containing the correct cell C1.

  Since the sequence command (PGC) is generated and the video objects (VOB) 1910 and 1920 are reproduced in order, the cell 420 ABCD is reproduced. The playback sequence is further controlled by video stream switching instructions 2011, 2021 to switch between video streams 1901 and 1902 at the appropriate point in the sequence. The correct video streams 1901, 1902 are calculated using a deterministic algorithm for each multi-angle block 2020. If the same deterministic algorithm is used during playback, playback occurs along the same path in the recorded video streams.

  In a preferred embodiment, the video stream switching instructions 2011 and 2021 are executed using a forced activation button instruction corresponding to the hidden menu button of the video object 2010 preceding one block of the multi-angle block group 2020. In this example, the video object (VOB) of the cell B includes a switching command 2011 for setting a specific parameter of SPRM3 to “2”. When the next video object (VOB) as a multi-angle block relating to the cell C is entered, it is determined by the set value of the specific parameter SPRM3 that the stream “2” needs to be reproduced, and in this case the cell C1 Is played. Further, in this example, the SPRM3 is set to the value “1” in the same manner by the video object (VOB) 2020 of the cell C, and preparation for playing the next cell is completed.

In the preferred embodiment, a sequence generator is used to determine the correct video stream playback sequence. One suitable sequence generator is based on a deterministic algorithm that incorporates one or more initial parameters, and from this deterministic algorithm, successive values are generated by applying a series of parameters to the generator. An example of such a sequence generator is a linear congruent generator, and when A and B are prime numbers, the next number is changed from the current number to rn + 1 = (A * r _n + B) mod. Defined by M as the method of generation.

FIG. 21 is an example table of short sequences provided by the values A = 7, B = 3, M = 17. If each multi-angle block contains (for example) 4 video streams, use (modulo 4 r _n ) +1 (returns a value in the range 1 to 4) as the basis for selecting a continuous angle. .

Accordingly, in the first multi-angle block 2020, the angle stream 1 is reproduced, and then the angle 4 of the second block is reproduced.
The original audiovisual data is played correctly only if the original cell is played for each of the multi-angle blocks, and to do this, parameters related to the sequence generator (A, B and M in this example) It is necessary to recognize the value of. Since there are many possible values for these parameters, one or more of these parameters can be used as a “key” to unlock the content. If the wrong parameter is selected and played, the wrong video sequence will be played during the playback of the multi-angle block, making it impossible to play the content (i.e. very unsatisfactory playback). ).

  That is, the method generates a deterministic algorithm with a repeated output sequence that varies with the initial parameters, and determines the video angle stream according to the sequence. The method also receives one or more parameters during playback of the audiovisual product, applies a deterministic algorithm to these parameters to generate an output sequence, and selects from among multiple video streams. Perform according to the generated sequence.

  FIG. 22 shows an exemplary DVD video navigation instruction for repeatedly executing the described LCG algorithm. Under the current version of the DVD video standard, only one instruction can be associated with a menu button. Therefore, it is preferable to use many consecutive cell forced activation buttons before entering the multi-angle block to execute the required instruction sequence each time the sequence generator is used repeatedly. That is, the program is actually executed using the instruction executed at the end of each of several preliminary video objects (VOBs) in sequence, sandwiched between each multi-angle block. According to this sequence, the specific parameter SPRM3 for recording the video angle number for reproduction is set to an appropriate value.

  FIG. 23 is a simple example for illustrating the basic features of a preferred scrambling method. Cells C1 and C2 are complete error cells and have been added as “spoofed” cells to the original content sequence as in the embodiment described above with reference to FIG. Similarly, cells B1, B2, B4, D2, D3 and D4 are all error cells. The original audiovisual data is reproduced only by following the path indicated by the thick line connecting cells A, B3 and D1. In order to take this path, it is necessary to select these video objects (VOB) in order by the correct sequence command (PGC), and further, by the correct video stream switching command, the inside of each multi-angle video object (VOB). It is necessary to select an appropriate stream. This synergistic combination results in audiovisual products having a very powerful preventive measure against unauthorized access such as copying or viewing.

[Lock / Unlock]
Another aspect of the invention relates to “locking” an audiovisual product, which requires an “unlock” before the user is allowed access to the audiovisual product.

  In a preferred embodiment of the present invention, the user provides the access code through an input device such as a keyboard or a portable remote control unit. Conveniently, the audiovisual product is set up with a startup sequence that prompts the user to enter an access code (eg, a first playback program chain (PGC)). Therefore, the correct program sequence instruction of the program chain (PGC) 321 can be obtained directly or indirectly by the access code.

  Yet another embodiment of the present invention has been developed so that vendors can publish video content on DVD video discs to allow playback on all DVD video players, where the content is “ It needs to be unlocked. This enables, among other things, pay-to-play applications as shown in the following scenario.

1. The end user receives a DVD video disc containing important content such as a magazine cover.
2. When a user plays a disc, he / she is prompted to enter an “unlock code” before the content or part of the content can be played.

  3. In order to obtain the unlock code, the user needs to call a premium-rate number or perform a credit card payment, for example.

4). If the unlock code is input when the disc is being played on the screen, the protected content can be played.
Many variations can be used according to the required security and functional levels, as outlined below.

Example 1:
In the first exemplary method, the disc content is unlocked using a single fixed unlock code. This can be, for example, a 4-digit PIN. On the screen, the user is presented with an image of a numeric keypad and can be locked in four digits by using remote control navigation buttons (eg, Up, Down, Left, Right, and Enter). it can. Preferably, as each digit is entered, the digit is displayed on the screen and is confirmed by the user. Of course, many other input options are also available.

Example 2:
An exemplary first method feature is that all users receive the same unlock code, so the security weakness is that one person can pass the unlock code to many other people, Lowers the level of access control. By using code pairs, security can be enhanced as follows.

  1. When prompting for an unlock code, the disc displays an “identification code”, which can be, for example, a four-digit code that is randomly selected by the playback device during playback.

  2. When a user purchases an unlock code, he / she must first quote the identification code, where each available identification code is set with the appropriate unlock code.

3. The user enters the unlock code to access the disc content.
A number of algorithms can be used to generate matching pairs of security codes, such as public / private key pairs.

  A feature of the exemplary second method is that a new identification code is generated for each session of DVD disc playback, and the unlock code is unique to each identification code. This means that when a user purchases an unlock code, this code can only be used to unlock the content once (pay once, play once). This configuration is desirable for some applications (eg, participation in competitions and the user will have to pay again each time he / she wants to participate in competitions), but in other applications Not desirable. For certain applications, it is desirable to be able to pay once and play multiple functions.

Example 3:
A modification is made to the exemplary second method to allow the user to enter an identification code using information that is unique to the user or limited to a small number of users. The following items can be cited as examples.

1. A trackable “customer number” assigned to a user (eg suitable for use by a company).
2. Customer's credit card number (customer may not give it to others).

  These various options for receiving an access code or unlock code can be used alone or in any combination, depending on the level of security required. With the access control and content security provided by the present invention, audiovisual products can be defined and generated in many innovative commercially valuable forms that are not yet available at this time. Some examples are shown in the following table.

  While playback is taking place, the content of the DVD video disc acts to allow the user to authenticate and play a valid video if the authentication passes or some other video if the authentication fails. It will act to regenerate.

Example 4:
In order to support the preferred embodiment of the present invention, certain steps are performed while preparing the content of the disc (ie authoring), and certain steps are performed during playback to authenticate the content. Unlock against.

During authoring, disc content is prepared as follows.
1. A function D is defined that is used to determine the destination on the disc that satisfies the following requirements and perform playback.

a. D to n values C ₁ , C ₂ . . . Parameterized by C _n , each of these values corresponds to a separate access code component, and these access code components are used together to unlock the content.

    b. The result of D obtained by making an estimate for all available values needs to be in the range of 1-m. As the value of m increases, the content protection level usually increases.

c. The range of each code C _i is C ₁ , C ₂ . . . It is set so that a very large number of input values can be used for D when C _n is combined.
d. A certain combination of C ₁ ′, C ₂ ′,... That ideally yields a unique output of D, D _unlock = D (C ₁ ′, C ₂ ′,... C _n ′). . . A value of C _n ′ (unlock code) exists. D _unlock is all values C ₁ , C ₂ . . . _If it is not unique with respect to C _n (ie, there are multiple unlock codes), ideally it should be as small as possible in the number of such possible combinations of values from which Dunlock can be obtained. There is.

2. Generate m destinations and execute the program with the following properties:
e. The destination D _unlock corresponds to smooth reproduction of the content to be protected.
f. All other destinations will play different content or fake content.

While playing a disc, perform the following steps:
1. Access codes C ₁ , C ₂ . . . To get the C _n.
2. Determine the destination D (C ₁ , C ₂ ... C _n ).

3. Jump to the destination.
Codes C ₁ , C ₂ . . . C _n can be taken from any of the examples listed above, including any combination of the following:

  1. PIN number provided to the user. This number can take the form of a simple four-digit code, for example. The user interface provided on the DVD video disc prompts, which in turn causes the user to enter each of the four digits. The prompt can be made by displaying a numeric keypad, through which the user selects a series of digits using standard DVD video remote control buttons (up, down, left, right, OK).

2. This number is unique to the current run and can be generated by a DVD video random number generator.
3. User private number such as credit card number, or customer code. This number is entered in the same manner as item 1 above.

Example 5:
Various approaches can be used to define the destination function D. For example, a primitive function simply returns a pass / fail result based on, for example, a PIN number. The next pseudo code returns 1 when the user enters a valid PIN code “1234” and returns 2 for all other codes.

Function D (C)
{
if C = 1234 then return 1 else return 2
}
On the disc, set up two destinations (1 and 2), 1 corresponds to the correct content to be unlocked, and 2 is like a still image showing the text “access denied” or Corresponds to different content. This approach provides only a very low level of protection-it is very easy for the reverse engineer to identify both the correct unlock code and the destination of the protected content on the disc. The advantage of this approach is that it is very simple to implement and only requires a simple authoring and playback method. This approach is therefore sufficient when content security is not an important requirement.

Example 6:
A slightly more secure approach is to use a one-way hash (hash) function that maps message M (usually of arbitrary length) to a fixed-length “message digest”. Function H. In this case,
1. H (M) is easy to calculate,
2. 2. What message digest MD is given, it is difficult to detect the corresponding message M having the structure MD = H (M), ie H cannot actually be reversed, and Given M and H (M), it is difficult to detect a message M ′ ≠ M such that H (M ′) = H (M).

  Thus, a one-way hash function compresses an arbitrarily long message into a certain value of a specified length—often called a “fingerprint” —to detect two different messages with the same fingerprint. Is a definitive algorithm that makes it impossible. Such functions are widely used in encryption, and widely used methods can include MD5, SHA, and Snefru.

  One-way hash functions are important because reverse engineers can evaluate the function to find the desired result, but there is no easy way to find the input value that will yield that result. .

A simple destination function D based on the hash function H is expressed as follows.
Function D (C)
{
if H (C) = MD then return 1 else return 2
}
In the above expression, MD is a predetermined message digest value, which is defined as the result of evaluating H (C) for the correct unlock code. Since H cannot be inverted, it is not easy for the reverse engineer to determine the value of C that causes the destination function to jump to the lock target content. However, it is still relatively easy for reverse engineers to replace or remove the hash function. The reason is that the desired destination (ie, “1”) can be easily determined from the code.

Example 7:
A more secure destination function depends on having a relatively large number of seemingly valid available destinations. For example, it is assumed that the function D (C) uses a 4-digit PIN code as an input. There are 10,000 available destinations, of which 9,999 respond with an “access denied” response, and one can edit the disc to be protected content. This can be done with the following very simple destination function:

Function D (C)
{
return C
}
Thus, security here relates to how easy it is for reverse engineers to identify the content to be protected from among many collections.

Thus, weak security becomes a technique used to determine the code used to unlock the correct destination.
When considering a one-time payment and one-time playback scenario, a reverse engineer can protect by buying unlock codes and using them many times for playback. It is important to ensure that it is not possible to easily extract the target content and transfer it to a disc that does not require authentication.

Example 8:
In another exemplary technique, the key pair is used as a parameter for the destination function, one of the keys is generated by the player, and the vendor provides a second matching key for unlocking the content. One embodiment of this approach can operate as follows.

1. The user plays the disk, random access code C ₁ This is, for example, is produced in the form of a 4-digit PIN. The code is displayed on the screen.
2. The user contacts the vendor, and provides the value of C _1.

3. Vendor supplies a matching code _{C 2} of Again e.g. 4 digits PIN.
4). When the user inputs C ₂ to the DVD video playback device, the playback device internally evaluates the destination as D (C ₁ , C ₂ ).

5). The DVD jumps to the calculated destination.
Here, an exemplary destination function is represented as follows.
Function D (C ₁ , C ₂ )
{
return (C ₁ + C ₂ ) mod 10000
}
In this case, the code supplied by the vendor and calculated in step 3 above is evaluated as follows if the correct destination is _Dunlock .

C ₂ = (D _unlock −C ₁ ) mod 10000 (Note: 0 ≦ C ₂ ≦ 10000)
For example, when the correct destination is 1234 and the DVD playback device presents a code of 5678, the corresponding code required to unlock the content is (1234-5678) mod 10000 = 5556.

Example 9:
Another example of a means for unlocking a destination is represented by the following pseudo code:
Ref = RND (10,000) #Random number 0. . . 9,999 are generated.

Display Ref Prompt Key # 'Key' is a 4-digit unlock key entered by the user.

Destination = (Ref XOR Key) mod 1000 + 1 # 1. . . 1000 target PGCs
Jump to PGC destination In the above expression, a random reference number is displayed. The user needs to contact the disc issuer to obtain a match key. The issuer calculates this key according to the following formula.

Key = D XOR Ref
In the above equation, 'D' is the correct destination-321- in this example. The user enters this key, calculates the destination, and jumps to the PGC where execution is applicable.

  Here, the above PIN code is used for illustration, and in practice, longer codes are appropriate to achieve a higher security level. The example destination function is very simple and not secure. In practice, one-way hash functions are preferred because they cannot be easily inverted.

The advantages of this method are as follows.
1. The destination code cannot be easily obtained by analyzing the instructions on the disk.
2. Each time a disc is played, a different code is generated that requires a different unlock code.

  The disadvantage is that a reverse engineer who recognizes the matching code pair that unlocks the disk will generate a copy of the disk and replace the instruction that generates the random number with an instruction that always generates a known generated key. It is possible to do. Thus, this new disk can always be unlocked using the known pair of unlock keys.

Example 10:
In another enhancement of the method, an irreversible transformation is applied to the true original code C ₁ to “make the code invisible”. That is, the true original code C ₁ acts as a seed for generating the first access code C ₁ ′ displayed to the user. In this case, the modified embodiment is as follows.

1. When the user playing the disc, random access code C ₁ is generated, for example, 4-digit PIN format.
2. Apply (irreversible) transformation T to C ₁ to generate C ₁ ′ = T (C ₁ ) and display this transformed code on the screen.

3. The user contacts the vendor and supplies the value of C ₁ '.
4). Using a large pre-calculated look-up table containing all available codes and the corresponding translated values of these codes, the vendor performs a table look-up to obtain C ₁ and the supplied C ₁ ' Generate from.

5). Using the generated C ₁ value, the vendor again obtains and supplies a match code C _2, for example in the form of a 4-digit PIN.
6). When the user enters a _{C 2,} internally destination is evaluated as _{D (C 1, C 2)} . (Note: The value C ₁ 'is no longer necessary)
7). The DVD jumps to the calculated destination.

The advantage of this method over the previous example is that the apparent values C ₁ ′ and C ₂ are not sufficient to unlock the disc content, but cannot be easily generated from the apparent values beforehand. it is that it requires the converted value C _1. This is because even though the reverse engineer can determine the method used in transformation T, this transformation is not reversible. The inverse transformation needs to be performed at the vendor office, and the inverse transformation is done at this office using a table lookup. This table is usually very large and will provide high security.

  While several preferred embodiments have been shown and described, those skilled in the art will recognize that various changes and modifications may be made without departing from the scope of the invention as defined in the appended claims. It will be appreciated that can be added in

  Attention will be paid to all the articles and documents filed in connection with this application at the same time or prior to this specification and disclosed for public search utilizing this specification, And the contents of all such articles and documents are included in the disclosure of the present invention by referring to these articles and documents.

  Any combination of all of the features disclosed herein (including all attached claims, abstracts and figures) and / or all of the method or process steps disclosed above. Except for combinations where at least some of these features and / or steps are incompatible with each other.

  Each feature disclosed in this specification (including all appended claims, abstracts, and figures) may be replaced with another feature serving the same, equivalent, or similar purpose unless otherwise indicated. . Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

  The present invention is not limited to the details of the previous embodiment (s). The invention may be any novel feature of any of the features disclosed herein, or any novel combination of these features (including all appended claims, abstracts, and figures), or It can be extended to any one new step or any new combination of these steps of all the methods or processes disclosed above.

Claims (39)

A method used to generate an audiovisual product (400) comprising:
Receiving original audiovisual data (700) to be played according to the original content sequence;
Dividing the original audiovisual data (700) into a plurality of cells (420);
Generating a plurality of sequence instructions (410), each sequence instruction generating a plurality of sequence instructions representing a playback sequence for reproducing the plurality of cells in a specified order; Multiple sequence instructions are
At least one correct sequence command (410a) for reproducing the original content sequence by the reproduction sequence;
A plurality of illegal sequence instructions (410b) in which the original content sequence is not reproduced by the reproduction sequence. The method of claim 1, wherein the dividing includes arranging the plurality of cells in a sequence other than the original content sequence. The method according to claim 1 or 2, comprising scrambling the original content sequence by arranging the plurality of cells in a crowded manner. A relatively large number of illegal sequence instructions (410b) and a relatively small number of correct sequence instructions (410a) are generated, and the relatively few incorrect sequence instructions (410a) are among a relatively large number of incorrect sequence instructions (410b). 4. The method according to any one of claims 1 to 3, comprising the step of making it concealed. The method according to any one of claims 1 to 4, wherein each of the illegal sequence instructions (410b) makes it impossible to successfully reproduce the audiovisual data (700) of the plurality of cells. The method according to any one of the preceding claims, wherein the dividing step comprises adding one or more error cells (421) that are not appropriate to the original content sequence. The method of claim 6, wherein each of the one or more error cells (421) includes a section of the original audiovisual data (700). The method of claim 7, comprising tampering with the original audiovisual data (700) in the one or more error cells (421). The plurality of sequence instructions (410) perform different changes while the audiovisual data (700) of the cell is being played, without duplicating the audiovisual data (700) itself. 9. The method according to any one of items 8. The plurality of sequence instructions (410) are formed as a permutation sequence such that the illegal sequence instruction (410b) is a permutation of the correct sequence instruction (410a). The method described in 1. Setting a plurality of structural locations in the audiovisual product (400);
11. The method of any one of claims 1 to 10, comprising assigning the plurality of sequence instructions (410) to the plurality of structural locations. 12. The method of claim 11, wherein the structural location assigned to the at least one correct sequence instruction (410a) or each at least one correct sequence instruction can be generated from an access code (80). Defining a destination function, wherein when the destination function is applied to the access code (80), the structural function of the correct sequence instruction (410a) is generated by the destination function when applied to the access code (80). 12. The method according to 12. The access code (80) includes a numeric value within a predetermined range such that when the destination function is applied to the numeric value of the access code (80), the destination function causes the structural location of the correct sequence instruction (410a). 14. The method of claim 13, wherein is calculated. 15. The method of claim 14, wherein when the destination function is applied to an illegal numeric value, the destination function calculates a structural location of one illegal sequence instruction of a plurality of illegal sequence instructions (410b). The method according to any one of claims 13 to 15, wherein the destination function comprises a one-way hash function. The method according to any one of claims 13 to 16, wherein the destination function operates with at least two access codes each having a plurality of numerical values. 18. The destination function is applied to generate a first access code to be displayed to a user, and the destination function operates with a second access code provided as a reply. The method according to item. The method of claim 18, comprising generating a seed with the destination function and applying a transformation to generate a first access code so that the seed of the first access code is not visible to the user. 20. A method according to any one of the preceding claims, wherein the plurality of sequence instructions (410) are formed as a plurality of program chains (PGC). The method according to any of the preceding claims, comprising adding at least one error cell (421) containing erroneous audiovisual data (700) to a plurality of cells (420). Assigning a plurality of cells (420) to at least a first video stream (1901) and a second video stream (1902);
Generating a video stream switching command (2011, 2021) for reproducing the plurality of cells (420) according to an original content sequence by switching between the first and second video streams (1901, 1902); The method according to any one of claims 1 to 21, further comprising: 24. A method according to any one of the preceding claims, wherein the audiovisual product (400) can be played according to the DVD video standard. 24. A method according to any one of the preceding claims, comprising recording the audiovisual product (400) on a portable random access storage medium (40). 25. A method according to any one of the preceding claims, comprising recording an audiovisual product (400) on an optical disc (40) according to the DVD video standard. A method for use in playback of an audiovisual product (400) comprising:
Receiving an audiovisual product (400) having a plurality of cells (420) of audiovisual data (700), wherein reproduction of the audiovisual data is controlled by a plurality of sequence instructions (410); The sequence command (410) includes at least one correct sequence command (410a) that plays the audiovisual product (400) according to the original playback sequence, and a plurality of illegal ones that do not play the audiovisual product (400) according to the original playback sequence. Receiving an audiovisual product (400) comprising sequence instructions (410b);
Selecting one sequence command from among the plurality of sequence commands (410);
Playing back the audiovisual data (700) of the plurality of cells according to a selected sequence instruction. Each of the plurality of sequence instructions (410) has a predetermined structural location within the audiovisual product (400), and the selecting step comprises:
Receiving an access code (80);
Determining a destination structure location in the audiovisual product (400) by applying a destination function to the access code (80);
27. Selecting a sequence instruction corresponding to the location by jumping to the determined destination structure location. The method of claim 27, wherein the access code (80) is entered by a user during playback of the audiovisual product (400). 29. A method according to claim 27 or 28, wherein the access code (80) is entered by a user through a user input device, such as a keypad or remote control unit, or other communication device. 30. A method according to any one of claims 27 to 29, wherein the destination function applied to the access code (80) is a mathematical function that returns a destination structure location according to a received access code (80). Receiving an audiovisual product (400) wherein the audiovisual data is divided into a plurality of cells (420), wherein the plurality of cells (420) provide the correct audiovisual data appropriate for the original content sequence; At least one correct cell including, at least one error cell including the erroneous audiovisual data (700) (421), and a selected cell of the plurality of cells (420) are reproduced in a specified order. Receiving an audiovisual product (400) comprising at least one sequence instruction (410) representing a playback sequence;
31. The method of any one of claims 26-30, further comprising: playing audiovisual data (700) of the plurality of cells (420) according to a sequence instruction (410). Receiving an audiovisual product (400) comprised of audiovisual data (700) and having a plurality of cells (420) that together represent the original content sequence, wherein the plurality of cells (420) is at least a first one. And receiving an audiovisual product that is divided into second video streams (1901, 1902);
One or more video stream switching instructions (2011, 2021) are executed to automatically switch between at least the first video stream (1901) and the second video stream (1902) during playback of the plurality of cells. And reproducing the audiovisual data (700) according to the original content sequence. 31. A method according to any one of claims 26 to 30, wherein the audiovisual product (400) can be played according to the DVD video standard. 31. A method as claimed in any one of claims 26 to 30, comprising playing an audiovisual product (400) from a portable random access storage medium (40). 31. A method according to any one of claims 26 to 30, comprising playing the audiovisual product (400) from the optical disc (40) according to the DVD video standard. 36. A recording medium having recorded thereon instructions for executing the method according to any one of claims 1 to 35 and executable by a computer. 36. An authoring device adapted to perform the method according to any one of claims 1-35. 36. An audiovisual product that operates to perform the method of any one of claims 1-35. 36. A DVD video recording or playback device adapted to perform the method according to any one of claims 1-35.

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