Broadcast transmission equipment and relay equipment

Abstract

To provide a broadcast transmission device and a relay device that can reproduce a scrambled content transmitted by digital broadcasting on various terminals.SOLUTION: A broadcast transmission device 100 includes sampling means 110 that divides a stream of a broadcast content to obtain a sample, sub-sampling means 120 that divides the sample into sub-samples such that each scrambled portion other than at least the last sub-sample is an integer multiple of the encryption key length, unitizing means 130 that stores the sub-samples in an MMTP packet and perform division into units in which at least the scramble portion in the MMTP packets other than the last unit is an integral multiple of the encryption key, scrambling means 150 that scrambles the scrambled portion to be scrambled for the sub-samples, and packetizing means 160 that stores the scrambled and unscrambled portions in separate MMTP packets when the sub-samples contain the scrambled portion and the unscrambled portion.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a broadcast transmission device and a relay device for a digital broadcast system. [Background technology]

[0002] Conventional digital broadcasting uses a conditional access system that limits reception of pay broadcasts to subscribers only, and a content protection system for free broadcasts (see Non-Patent Document 1).

[0003] Meanwhile, DRM (Digital Rights Management), a technology known for protecting communication content, is primarily known as Microsoft's PlayReady, Google's Widevine, Apple's Fairplay, etc. A known scrambling (content encryption) method for achieving compatibility with a variety of communication terminals that support these different DRM technologies is the MPEG (Moving Picture Experts Group) method known as CENC (Common Encryption) (see Non-Patent Document 2).

[0004] This method is an international standard technology that enables the same scrambled content to be decrypted in the same way using different DRMs and key management systems. Specifically, by including support information for multiple DRMs in the header of a single scrambled content, any communication device that supports any DRM can obtain the appropriate license from the license server and decrypt and play the scrambled content. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] ARIB STD-B61 "Access control method (2nd generation) and CAS program download method for digital broadcasting" Part 1 "Access control method (2nd generation)" [Non-patent document 2] ISO / IEC 23001-07 “Information technology-MPEG systems technologies-Part7:Common encryption in ISO base media file format files” Summary of the Invention [Problem to be solved by the invention]

[0006] In the future, broadcast content will be viewed not only on conventional broadcast receiving terminals equipped with tuners, but also on various communication terminals, such as smartphones and tablets, where broadcast content transmitted via broadcasting will be relayed by a relay device equipped with a tuner over in-home communication lines. In such cases, from the perspective of content protection, it is desirable for broadcast content to be relayed in its scrambled state.

[0007] In the access control method for digital broadcasting that uses MMT (MPEG Media Transport, ISO / IEC 23008-1) as the multiplexing method, scrambling is performed on an MMTP packet basis, with the data portion of the MMTP payload in the MMTP packet that transmits the broadcast content as the range.

[0008] On the other hand, the CENC method used in communication content such as MPEG-DASH (ISO / IEC 23009-1) includes a full sample encryption method in which the entire sample (e.g., one frame of video or audio) is scrambled as a unit, and a subsample encryption method in which the sample is scrambled in subsample units consisting of an unscrambled portion and a scrambled portion.

[0009] Although it is possible to use a common encryption algorithm (such as AES CTR mode) for broadcast content and communication content, because the scrambling units are different, there was no established method for relaying scrambled broadcast content to a communication terminal and enabling descrambling and playback at the communication terminal.

[0010] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a broadcast transmitting device and a relay device that enable scrambled content transmitted by digital broadcasting to be played back on a variety of terminals. [Means for solving the problem]

[0011] The broadcast transmission device according to the first aspect is a broadcast transmission device for a digital broadcast system that uses MMT as a multiplexing method, and comprises: sampling means for dividing a stream of video or audio broadcast content to obtain samples; subsampling means for dividing the samples to obtain subsamples whose scrambled parts are integer multiples of the encryption key length for at least the last subsample; unitization means for dividing the subsamples to obtain units whose size fits into an MMTP packet and whose scrambled parts in the MMTP packet are integer multiples of the encryption key for at least the last unit; scrambling means for scrambling the scrambled parts that are to be scrambled in the units; and, if the unit includes a non-scrambled part that is not to be scrambled and the scrambled part, packetization means for storing the scrambled scrambled part and the non-scrambled part in separate MMTP packets.

[0012] The relay device of the second aspect is a relay device for a digital broadcasting system that uses MMT as a multiplexing method, and comprises: separation means for extracting from a received stream unscrambled MMTP packets that store unscrambled portions of subsamples that are not to be scrambled, and scrambled MMTP packets that store scrambled portions of the subsamples; restoration means for restoring scrambled content comprising the subsamples from the unscrambled portions obtained from the unscrambled MMTP packets and the scrambled portions obtained from the scrambled MMTP packets; and transmission means for transmitting the restored scrambled content to a communication terminal via a communication network without performing scrambling decoding. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a broadcast transmitting device and a relay device that enable scrambled content transmitted by digital broadcasting to be played back on various terminals. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a configuration of a digital broadcasting system according to an embodiment; [Figure 2] FIG. 1 is a diagram for explaining an overview of a multiplexing method in a digital broadcasting system according to an embodiment. [Figure 3] 1 is a diagram showing the configuration of a broadcast transmission device according to an embodiment. [Figure 4] 3A and 3B are diagrams for explaining the operation of the broadcast transmission device according to the embodiment. [Figure 5] 3A and 3B are diagrams for explaining the operation of the broadcast transmission device according to the embodiment. [Figure 6] FIG. 10 is a diagram showing the configuration of senc included in moof according to the embodiment. [Figure 7] FIG. 2 is a diagram showing the configuration of a scrambling means according to the embodiment. [Figure 8]FIG. 10 is a diagram illustrating the configuration of a multi-type header extension according to an embodiment. [Figure 9] 1 is a diagram illustrating the configurations of a broadcast receiving terminal, a relay device, and a communication terminal according to an embodiment. [Figure 10] FIG. 1 is a flow diagram illustrating a multiplexing method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] The embodiments will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0016] (Digital Broadcasting System) First, a digital broadcasting system according to this embodiment will be described. Fig. 1 is a diagram showing the configuration of a digital broadcasting system 1 according to this embodiment.

[0017] As shown in FIG. 1, the digital broadcasting system 1 according to this embodiment is a broadcasting system based on the ARIB standard, and includes a broadcast transmitting device 100, a broadcast receiving terminal 200, a relay device 300, and a communication terminal 400.

[0018] The broadcast transmission device 100 is a device that transmits scrambled broadcast content (scrambled content). The broadcast transmission device 100 is installed in, for example, a broadcast station. In this embodiment, the broadcast transmission device 100 containerizes broadcast content, which is media data such as video and audio, in ISO-BMFF (ISO / IEC 14496-12) format and transmits it as an MMTP stream based on the MMT standard.

[0019] The broadcast receiving terminal 200 is an example of a receiving device that receives scrambled content via a broadcast transmission path 10. The broadcast transmission path 10 may be any broadcast transmission path, such as a transmission path for terrestrial broadcasting, satellite broadcasting, or cable broadcasting. The broadcast receiving terminal 200 is a terminal equipped with a broadcast receiving function such as a tuner, and receives scrambled content transmitted via digital broadcasting, descrambles the received scrambled content, and plays back the broadcast content. The broadcast receiving terminal 200 performs scramble decoding (hereinafter referred to as "broadcast scramble decoding") in accordance with the digital broadcast access control method defined in ARIB STD-B61 (hereinafter referred to as the "ARIB method").

[0020] Relay device 300 is another example of a receiving device that receives scrambled content via broadcast transmission path 10. Relay device 300 is a relay device equipped with a broadcast receiving function such as a tuner, receives scrambled content transmitted by digital broadcasting, and relays the scrambled content to communication terminal 400 via communication network 20 without performing scrambling and decoding. Communication network 20 is, for example, a local area network (LAN) installed in a home. The LAN may also be a wireless LAN.

[0021] Communication terminal 400 is a terminal that does not have a broadcast receiving function. Communication terminal 400 is, for example, a personal computer (PC), a smartphone, or a tablet terminal. Communication terminal 400 receives scrambled content relayed by relay device 300 via communication network 20, descrambles the received scrambled content, and plays back the broadcast content. Communication terminal 400 performs scramble decoding (hereinafter referred to as "communication scramble decoding") in accordance with the CENC method, which is a scrambling method for communication content.

[0022] In this way, by relaying scrambled content to communication terminal 400 by relay device 300, even communication terminal 400 that does not have a broadcast receiving function can play back the broadcast content. Here, since the content is transmitted in a scrambled state over communication network 20, content protection can also be ensured. However, since the ARIB system is not compatible with the CENC system in terms of scrambling method, it is difficult for communication terminal 400 to perform communication scrambling decoding on broadcast content scrambled using the ARIB system.

[0023] Therefore, in this embodiment, the broadcast transmission device 100 scrambles and multiplexes broadcast content in a manner that conforms to the ARIB system and is compatible with the CENC system, and transmits the scrambled content, thereby enabling the communication terminal 400 to perform communication scrambling decoding on the scrambled content.

[0024] Fig. 2 is a diagram for explaining an outline of the multiplexing method in the digital broadcasting system 1 according to this embodiment. Fig. 2(a) shows a comparison between the ARIB system and the CENC system, and Fig. 2(b) shows an outline of the multiplexing method according to this embodiment.

[0025] As shown in Figure 2(a), the ARIB method scrambles the data portion of the MMTP payload in the MMTP packet as the scrambling range, and the scrambling initial value (IV: Initialization Vector) used for scrambling is set for each MMTP packet.

[0026] On the other hand, the CENC method of subsample encryption scrambles each subsample obtained by dividing a sample (for example, one frame of video or audio). However, it does not scramble the header information (non-scrambled part) of the content, but only the scrambled part. The initial value (IV) used for scrambling is set on a sample-by-sample basis.

[0027] As shown in Figure 2(b), the multiplexing method according to this embodiment divides a sample and subsamples it so that each scrambled portion is an integer multiple of the encryption key length. Each subsample is then further divided into units that fit within an MMTP packet and whose scrambled portion within the MMTP packet is an integer multiple of the encryption key length. This completes the scrambling process for each MMTP packet (the subsample and the unit may be equal). This satisfies the scrambling unit constraints imposed by both the ARIB and CENC methods. However, the scrambled portion of the last subsample of a sample does not have to be an integer multiple of the encryption key length. Furthermore, the scrambled portion of the last unit of the last subsample does not have to be an integer multiple of the encryption key length.

[0028] Furthermore, the multiplexing method according to this embodiment stores the unscrambled and scrambled parts of the subsamples in separate MMTP packets, and the payload of the MMTP packet carrying the scrambled part is used as the scrambling range, thereby satisfying the constraints on the scrambling range of both the ARIB and CENC methods.

[0029] Furthermore, in the multiplexing method according to this embodiment, the IV of the unit containing the first scrambled part of a sample is the same as the IV of the sample, and the IVs for the second and subsequent units are set for each MMTP packet based on the IV of the unit containing the immediately preceding scrambled part, thereby satisfying the constraints on the initial scramble values ​​of both the ARIB and CENC methods.

[0030] The multiplexing method according to this embodiment employs an encryption algorithm that can be used in both the ARIB and CENC systems as the encryption algorithm used for scrambling, which is the AES CTR mode.

[0031] By using this multiplexing method, it is possible to scramble and multiplex broadcast content in a manner that is compatible with the CENC system while conforming to the ARIB system, and therefore it is possible for both the broadcast receiving terminal 200 and the communication terminal 400 to descramble the same scrambled content. This makes it possible to play scrambled content transmitted by digital broadcast on a variety of terminals.

[0032] (Broadcast transmission equipment) Next, the broadcast transmission device 100 according to this embodiment will be described. Fig. 3 is a diagram showing the configuration of the broadcast transmission device 100 according to this embodiment. Fig. 4 and Fig. 5 are diagrams for explaining the operation of the broadcast transmission device 100 according to this embodiment.

[0033] As shown in FIG. 3, the broadcast transmission device 100 of this embodiment has a sampling means 110, a sub-sampling means 120, a unitization means 130, a containerization means 140, a scrambling means 150, a packetization means 160, and a multiplexing means 170.

[0034] 4(a) and 4(b), the sampling means 110 divides the video and audio streams of the input broadcast content into samples, for example, for each frame. The broadcast content includes, for example, a video stream with a NAL (Network Abstraction Layer) structure encoded by a video coding method such as H.264|MPEG-4 AVC (Advanced Video Coding) or H.265|MPEG-H HEVC (High Efficiency Video Coding), and an audio stream such as MPEG-4 AAC (Advanced Audio Coding).

[0035] The subsampling means 120 determines a sample scramble initial value, which is scramble initial value information for each sample, and divides the video and audio samples into subsamples as shown in FIGS. 4(b) and 4(c).

[0036] At this time, in the video frame of the NAL structure, the subsampling means 120 may use a plurality of non-VCL (Video Coding Layer) NAL units arranged before the VCL (Video Coding Layer) NAL unit as a subsample different from the VCL NAL unit. Further, as shown in FIGS. 4(c) and (d), the subsampling means 120 may divide the subsample into an unscrambling part and a scrambling part. At this time, the scrambling part is made to be an integer multiple of the encryption key length (however, the scrambling part does not have to be an integer multiple of the encryption key length only for the last subsample). The unscrambling part is, for example, a non-VCL NAL unit, or a part (NAL header) including the NAL unit length and NAL unit type located at the head of the VCL NAL units. Also, in order to make the scrambling part an integer multiple of the encryption key length, a part having a length corresponding to the remainder obtained by dividing by an integer multiple of the encryption key length, which is located at the head of the data of the VCL NAL unit following the NAL header, is made the unscrambling part.

[0037] As shown in FIG. 4(e), the unitizing means 130 divides the subsample into units so as not to exceed a preset maximum size (for example, 1400 bytes) of the MMTP packet. At this time, when the unit includes a scrambling part, the scrambling part is made to be an integer multiple of the encryption key length (however, it does not have to be an integer multiple of the encryption key length only for the last unit of the last subsample). For example, as shown in FIG. 4(d), when the scrambling part has a length that is N times the encryption key length, the unitizing means 130, as shown in FIG. 4(e), for units #1 and #2 including the scrambling part, sets the length of the scrambling part of unit #1 to be n times the encryption key length (n < N), and sets the length of the scrambling part of unit #2 to be (N - n) times the encryption key length.

[0038] The containerization means 140 generates meta information for containerizing samples in the ISO-BMFF format. As shown in FIG. 5(a), the containerization means 140 generates header information for moov, moof, and mdat. Here, moov is initialization information for the entire stream, including encoding parameters for the input video and audio streams, and corresponds to meta information for the entire media. moof is meta information for movie fragments, which are groups of samples, either individually or in a reference encoding relationship. In other words, moof is movie fragment meta information for containerizing in the ISO-BMFF format movie fragments, which are groups of one or more samples. mdat stores samples for each group. The mdat length and type are stored at the beginning of mdat. moof and mdat constitute a movie fragment.

[0039] Regarding scrambling, based on the CENC standard, it is possible to place in moov pssh, which contains information indicating where to obtain the encryption key, schm, which contains information about the encryption algorithm, tenc, which contains default parameters, etc. In addition, it is possible to place in moof sbgp and sgpd, which contain identifiers for identifying the pssh and moof encryption keys, and saiz, saio, and senc, which contain information about the scrambling of samples and subsamples.

[0040] Fig. 6 is a diagram showing the configuration of senc included in moof according to this embodiment. As shown in Fig. 6, senc according to this embodiment has sample_count indicating the number of samples in a movie fragment, InitializationVector and subsample_count for each sample, and BytesOfClearData and BytesOfProtectedData for each subsample. Here, InitializationVector is the scramble initial value for the corresponding sample, and subsample_count is a value indicating the number of subsamples in the corresponding sample. BytesOfClearData is a value indicating the number of bytes of the unscrambled part in the corresponding subsample, and BytesOfProtectedData is a value indicating the number of bytes of the scrambled part in the corresponding subsample.

[0041] The scrambling means 150 uses a separately set encryption key to sequentially scramble the samples, starting from the first sub-sample, in AES 128-bit CTR mode. Fig. 7 is a diagram showing the configuration of the scrambling means 150 according to this embodiment.

[0042] As shown in FIG. 7, the scrambling means 150 includes a block dividing means 151, a counter means 152, an AES encryption means 153, a block encryption means 154, and an MMTP packet scrambling initial value setting means 155.

[0043] The block dividing means 151 divides the scrambled part of the unit into blocks each having an encryption key length (for example, 16 bytes).

[0044] The counter means 152 outputs a value obtained by adding the sample scrambling initial value and the counter value. Here, the counter value is 0 for the first block of the unit including the first scrambled part of the sample, and is continuously incremented by 1 for each block until scrambling of all blocks of all units in the sample is completed. When scrambling of the sample is completed, the counter value is reset to 0.

[0045] The AES encryption means 153 generates an AES cipher for each block from the output of the counter means 152 and the encryption key.

[0046] The block encryption means 154 encrypts the corresponding block with the AES cipher generated by the AES encryption means 153 and outputs scrambled data.

[0047] The MMTP packet scramble initial value setting means 155 sets the sum of the counter value of the first block of the scrambled part of a unit and the sample scrambled initial value as the MMTP packet scrambled initial value of that unit. Specifically, for units obtained by dividing a sample and further dividing multiple sub-samples into units of a size that fits into an MMTP packet and whose scrambled part is an integer multiple of the encryption key length (only for the last unit of the last sub-sample, the scrambled part does not have to be an integer multiple of the encryption key length), the MMTP packet scramble initial value setting means 155 sets the sample scrambled initial value, which is the scrambled initial value of that sample, as the MMTP packet scrambled initial value for the first unit. Furthermore, the MMTP packet scrambled initial value setting means 155 sets the MMTP packet scrambled initial value for each unit from the second unit onwards to a value obtained by adding a predetermined value to the MMTP packet scrambled initial value of the unit including the immediately preceding scrambled part. The predetermined value is a value obtained by dividing the number of bytes of the scrambled part of the unit including the immediately preceding scrambled part by the number of bytes of the encryption key (16 bytes).

[0048] The packetization means 160 generates an MMTP packet based on meta-information for containerization in ISO-BMFF format, the scrambled unit, and the MMTP packet scrambling initial value, and performs MMTP packetization.

[0049] As shown in Fig. 5(b), the packetization means 160 packetizes metadata of the entire media, such as moov, as an MMTP packet (non-scrambled MMTP packet) with fragment_type of 0 in the MMT standard. The packetization means 160 also packetizes movie fragment meta information (moof) and the byte length (mdat length) and type field of mdat as an MMTP packet with fragment_type of 1. The packetization means 160 also packetizes sub-sample data in mdat as an MMTP packet with fragment_type of 2.

[0050] As described above, the scrambling means 150 scrambles the scrambled portion of the unit that is the target of scrambling, and does not scramble the non-scrambled portion. The packetizing means 160 MMTP packetizes a unit that includes a scrambled portion and a non-scrambled portion by storing the scrambled portion and the non-scrambled portion in the payload of separate MMTP packets.

[0051] Information about the scrambling of the MMTP packet that stores the unit can be written using a multi-type header extension with the multi-extension header type set to 0x0001, based on ARIB STD-B61. In other words, the scrambling information is stored in the extension header field in the header of the MMTP packet.

[0052] 8 is a diagram showing the configuration of a multi-type header extension according to this embodiment, part of which is taken from Figure 3-1 of ARIB STD-B61, version 1.4.

[0053] As shown in Figure 8, in the case of an MMTP packet carrying an unscrambled portion (unscrambled MMTP packet), the packetization means 160 indicates that the MMTP packet has not been scrambled by setting the MMTP scramble control bit of the multi-type header extension to 0x00 or by not using the multi-type header extension.

[0054] In the case of an MMTP packet carrying a scrambled portion (scrambled MMTP packet), the packetization means 160 sets the MMTP scramble control bit to 0x10 (scrambled, even key) or 0x11 (scrambled, odd key), sets the MMTP initial value control bit to 0x01, and stores the MMTP packet scramble initial value of the MMTP packet as MMT scramble initial value information, thereby indicating that the packet has been scrambled. Note that whether the currently used encryption key is an odd key or an even key is separately identified by an ECM (Entitlement Control Message), which is key-related information common to each receiving device. For details on the ECM, see ARIB STD-B61.

[0055] The multiplexing means 170 receives the MMTP packets sequentially from the packetizing means 160, multiplexes them into one stream, and sends it out.

[0056] (broadcast receiving terminals, relay devices, communication terminals) Next, a description will be given of the broadcast receiving terminal 200, relay device 300, and communication terminal 400 according to this embodiment. Fig. 9 is a diagram showing the configurations of the broadcast receiving terminal 200, relay device 300, and communication terminal 400 according to this embodiment.

[0057] As shown in FIG. 9, the broadcast receiving terminal 200 includes a demultiplexing means 210, a broadcast scrambling decoding means 220, and a reproducing means 230.

[0058] The demultiplexing means 210 demultiplexes the stream received via the broadcast transmission path 10 to extract the scrambled content. The broadcast scramble decoding means 220 performs scramble decoding (i.e., broadcast scramble decoding) on ​​the scrambled content at the MMTP layer based on ARIB STD-B61 to restore the broadcast content. The playback means 230 plays back the broadcast content.

[0059] The relay device 300 includes a separating means 310 , a container restoring means 320 , and a transmitting means 330 .

[0060] The demultiplexing means 310 extracts scrambled content by demultiplexing the stream received via the broadcast transmission path 10. Specifically, the demultiplexing means 310 extracts from the received stream unscrambled MMTP packets storing the unscrambled portions of the subsamples that are not subject to scrambling, scrambled MMTP packets storing the scrambled portions of the subsamples, unscrambled MMTP packets storing metadata for the entire media such as moov, and unscrambled MMTP packets storing movie fragment meta information (moof) and the byte length (mdat length) and type field of the mdat (see FIG. 5(b)).

[0061] The container restoration means 320 restores scrambled content in ISO-BMFF format from the unscrambled and scrambled parts of each subsample, metadata for the entire media such as moov, and the movie fragment meta information (moof) and the mdat byte length (mdat length) and type field (see Figure 5(a)).

[0062] The transmitting means 330 transmits the scrambled content restored by the container restoring means 320 to the communication terminal 400 via the communication network 20 without performing descrambling.

[0063] The communication terminal 400 includes a receiving means 410 , a communication scramble decoding means 420 , and a reproducing means 430 .

[0064] The receiving means 410 receives scrambled content in ISO-BMFF format from the relay device 300. The communication descrambling means 420 performs descrambling (i.e., communication descrambling) on ​​the scrambled content based on the CENC standard to restore the broadcast content. The playing means 430 plays the broadcast content.

[0065] (Multiplexing method) Next, a description will be given of a multiplexing method in the broadcast transmission device 100 according to this embodiment. Fig. 10 is a flow chart showing the multiplexing method according to this embodiment.

[0066] In this flow diagram, it is assumed that the ISO-BMFF meta information, including the moov metadata for the entire media, has already been created and transmitted. Also, movie fragments are generated in units (groups) of G samples. Furthermore, the encryption key is set separately, and in this flow diagram it is assumed to be an even key.

[0067] As shown in FIG. 10, in step S1, the sampling means 110 sets a loop counter i to 0.

[0068] In step S2, the sampling means 110 separates sample (i), which is the ith sample in the group, from the input stream.

[0069] In step S3, the subsampling means 120 divides the sample (i) into subsamples (e.g., L subsamples) such that the sample (i) includes an unscrambled portion and / or a scrambled portion, which is a portion that is scrambled, and the scrambled portion (except for the last subsample) is an integer multiple of the encryption key length.

[0070] In step S4, each subsample is divided into units of a predetermined size (for example, 1400 bytes) or less, and the scrambling part is an integer multiple of the encryption key length (the subsample length and the unit length may be equal (only the last unit of the last subsample does not have to be an integer multiple of the encryption key length)).

[0071] In step S5, the scrambling means 150 determines a sample scrambling initial value IVs(i) which is the scrambling initial value for sample (i), and sets a counter C to zero.

[0072] In step S6, the scrambling means 150 sets the loop counter j of the unit to 0, sets the number of units to M, and starts scrambling processing for each sub-sample.

[0073] In step S7, the scrambling means 150 sets IVss(j), which is the scrambling initial value (MMTP packet scrambling initial value) of unit (j), to IVs(i)+C.

[0074] In step S8, the scrambling means 150 divides the scrambled part of unit (j) into blocks of 16 bytes each (the last unit of the last subsample may be less than 16 bytes).

[0075] In step S9, the scrambling means 150 sets the block loop counter k to 0, sets the number of blocks in unit (j) to N, and starts processing each block in unit (j).

[0076] In step S10, the scrambling means 150 scrambles the block (k) using AES 128 bits based on the encryption key, the sample scramble initial value, and the counter addition value (IVs(i)+C).

[0077] In step S11, the scrambling means 150 increments (ie adds 1 to) the counter C and the loop counter k of the block.

[0078] In step S12, the scrambling means 150 determines whether the loop counter k of the block is smaller than N. If the loop counter k of the block is smaller than N (step S12: YES), that is, if processing for all blocks of unit (j) has not been completed, the process returns to step S10 and proceeds to processing the next block.

[0079] On the other hand, if the loop counter k of the block reaches N (step S12: NO), that is, if the processing for all blocks of unit (j) is completed, in step S13, the scrambling means 150 increments the loop counter j of the unit.

[0080] In step S14, scrambling means 150 determines whether loop counter j of the unit is smaller than M. If j is smaller than M (step S14: YES), that is, if processing has not been completed for all units of all subsamples of sample (i), the process returns to step S7 and proceeds to processing the next unit.

[0081] On the other hand, if the loop counter j of the unit reaches M (step S14: NO), that is, if the processing for all units of all sub-samples is completed, in step S15, the scrambling means 150 increments the loop counter i of the sample.

[0082] In step S16, the scrambling means 150 determines whether the loop counter i of the sample is smaller than G. If the loop counter i of the sample is smaller than G (step S16: YES), that is, if processing for all samples in the group has not been completed, the process returns to step S2 and proceeds to processing the next sample.

[0083] On the other hand, if the sample loop counter i has reached G (step S16: NO), that is, if processing for all samples in the group has been completed, in step S17, the containerization means 140 generates movie fragment meta information (senc of moof) including sample scramble initial values ​​IVs (0 to G-1) for each sample (0 to G-1) in the group and information on the number of bytes in the unscrambled and scrambled parts of the subsamples (0 to L-1), and also generates a header (mdat length and type) of mdat that stores the samples (0 to G-1). The packetization means 160 generates and transmits these as MMTP packets with fragment_type set to 1.

[0084] In step S18, the packetizing means 160 resets the loop counter j of the unit to 0 and starts processing for each unit.

[0085] In step S19, the packetizing means 160 generates and transmits the unscrambled portion of unit (j) as an MMTP packet with the MMTP scrambling control bit of the multi-type header extension set to 0x00, or without using the multi-type header extension.

[0086] In step S20, the packetization means 160 generates and transmits the scrambled portion of unit (j) as a scrambled MMTP packet with the MMTP scramble control bit of the multi-type header extension set to 0x10 (scrambled, even key) and the MMTP initial value control bit set to 0x01, and the MMT scramble initial value information set to IVss(j).

[0087] In step S21, the packetizing means 160 increments the loop counter j of the unit.

[0088] In step S22, packetization means 160 determines whether loop counter j of the unit is smaller than M. If loop counter j of the unit is smaller than M (step S22: YES), that is, if processing for all units of all subsamples has not been completed, the process returns to step S19 and proceeds to processing of the next unit.

[0089] On the other hand, if the loop counter j of the unit reaches M (step S22: NO), that is, if processing has been completed for all units of all subsamples, multiplexing of one movie fragment is completed and processing ends.

[0090] (Summary of the embodiment) As described above, the broadcast transmission device 100 according to this embodiment is a broadcast transmission device 100 for a digital broadcasting system 1 that uses MMT as the multiplexing method, and includes: sampling means 110 that divides a stream of video or audio broadcast content to obtain samples; subsampling means 120 that divides the samples to obtain subsamples whose scrambled portions each have an integer multiple of the encryption key length; unitization means 130 that divides the subsamples to obtain units whose size fits into an MMTP packet and whose scrambled portions within the MMTP packet have an integer multiple of the encryption key length; scrambling means 150 that scrambles the scrambled portions of the units that are to be scrambled; and, if a unit includes both a scrambled portion and an unscrambled portion that is not to be scrambled, packetization means 160 that stores the scrambled scrambled portion and the unscrambled portion in separate MMTP packets. However, the scrambled portion of the last subsample of a sample does not have to be an integer multiple of the encryption key length. Furthermore, only for the last unit of the last subsample, the scrambled part does not have to be an integer multiple of the encryption key length.

[0091] This allows the restrictions on scrambling units and scrambling ranges of both the ARIB and CENC systems to be satisfied, making it easier to scramble and multiplex broadcast content in a manner that is compatible with the CENC system while conforming to the ARIB system.

[0092] In this embodiment, the scrambling means 150 has an MMTP packet scrambling initial value setting means 155 that sets an MMTP packet scrambling initial value, which is a scrambling initial value on a unit-by-unit basis. The packetizing means 160 generates a scrambled MMTP packet that includes a scrambled portion in the payload and includes the MMTP packet scrambling initial value in the extension header field.

[0093] Specifically, for units obtained by further dividing a plurality of subsamples obtained by dividing a sample, the MMTP packet scramble initial value setting means 155 sets the MMTP packet scramble initial value for the first unit to the sample scramble initial value, which is the scramble initial value for the sample, and sets the MMTP packet scramble initial value for each unit from the second onwards to a value obtained by adding a predetermined value to the MMTP packet scramble initial value of the unit including the immediately preceding scrambled part. The predetermined value is a value obtained by dividing the number of bytes of the scrambled part of the unit including the immediately preceding scrambled part by the number of bytes of the encryption key.

[0094] This allows the constraints on the scrambling initial value (IV) of both the ARIB and CENC systems to be met, making it easier to scramble and multiplex broadcast content in a manner that is compatible with the CENC system while complying with the ARIB system.

[0095] In this embodiment, the packetization means 160 generates an unscrambled MMPT packet that contains the unscrambled portion in its payload as an MMPT packet separate from the MMPT packet that stores the scrambled portion, thereby allowing the unscrambled portion to be properly multiplexed and transmitted by the MMPT packet.

[0096] In this embodiment, the containerization means 140 generates movie fragment meta information for containerization in ISO-BMFF format for movie fragments, which are groups of one or more samples. The movie fragment meta information includes, for each sample constituting a group, a sample scrambling initial value, information on the number of subsamples constituting the sample, and information on the number of bytes of the unscrambled portion and the scrambled portion of each subsample constituting the sample. The packetization means 160 generates an MMPT packet containing movie fragment meta information in its payload as an MMPT packet separate from the MMPT packet storing the scrambled portion and the MMPT packet storing the unscrambled portion. This allows the movie fragment meta information to be properly multiplexed and transmitted using the MMPT packet.

[0097] In this embodiment, the scrambling means 150 performs scrambling in AES CTR mode. Since the AES CTR mode is an encryption algorithm common to the ARIB system and the CENC system, by performing scrambling in AES CTR mode, it becomes easy to scramble and multiplex broadcast content in a manner that is compatible with the CENC system while conforming to the ARIB system.

[0098] The relay device 300 of this embodiment is a relay device 300 for a digital broadcasting system 1 that uses MMT as a multiplexing method, and includes a separation means 310 that separates from the received stream into unscrambled MMTP packets that store the unscrambled portions of the subsamples that are not to be scrambled, and scrambled MMTP packets that store the scrambled portions of the subsamples, a container restoration means 320 that restores scrambled content comprising the subsamples from the unscrambled portions obtained from the unscrambled MMTP packets and the scrambled portions obtained from the scrambled MMTP packets, and a transmission means 330 that transmits the restored scrambled content to the communication terminal 400 via the communication network 20 without performing scrambling decoding.

[0099] This allows broadcast content to be played back even on communication terminals 400 that are not equipped with a broadcast receiving function. Here, since the broadcast content is transmitted in a scrambled state over communication network 20, content protection can also be ensured.

[0100] As described above, according to this embodiment, scramble decoding (broadcast scramble decoding) is possible in the MMT layer based on ARIB STB-B61, and it is also possible to demultiplex the MMT layer while scrambling, extract broadcast content in ISO-BMFF format, and perform scramble decoding (communication scramble decoding) in the ISO-BMFF layer based on the CENC standard. Therefore, broadcast content transmitted via digital broadcasting can be descrambled and played back at the broadcast receiving terminal 200, and the content can be relayed to the communication terminal 400 via the communication network 20 while still scrambled, and can be descrambled and played back at the communication terminal 400.

[0101] (Other embodiments) In the above embodiment, an example of using AES CTR mode as the encryption algorithm has been described, but any encryption algorithm common to the ARIB system and the CENC system will suffice, and if such a common encryption algorithm is newly introduced, the new encryption algorithm may be adopted instead of AES CTR mode.

[0102] A program may be provided that causes a computer to execute each process performed by each of the above-mentioned devices (broadcast transmitting device 100, broadcast receiving terminal 200, relay device 300, and communication terminal 400). The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or DVD-ROM. Furthermore, circuits that execute each process performed by each of the above-mentioned devices (broadcast transmitting device 100, broadcast receiving terminal 200, relay device 300, and communication terminal 400) may be integrated, and the device may be configured as a semiconductor integrated circuit (chip set, SoC).

[0103] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes can be made within the scope that does not deviate from the gist of the invention. [Explanation of symbols]

[0104] 1: Digital broadcasting system 10: Broadcast transmission path 20: Communication Network 100: Broadcast transmission device 110: Sampling means 120: Subsampling means 130: Unitization means 140: Containerization methods 150: Scrambling method 151: Block division means 152: Counter means 153 :AES encryption method 154: Block encryption means 155: MMTP packet scrambling initial value setting means 160: Packetization means 170: Multiplexing means 200: Broadcast receiving terminal 210: Separation means 220: Broadcast scramble decoding means 230: Regeneration means 300: Relay device 310: Separation means 320:Container restoration method 330: Transmission means 400: Communication terminal 410: Receiving means 420: Communication scramble decoding means 430: Regeneration means

Claims

1. A broadcast transmission device for a digital broadcasting system using MMT as a multiplexing method, a sampling means for dividing a stream of video or audio broadcast content to obtain samples; subsampling means for dividing the sample to obtain subsamples whose scrambled parts are each an integer multiple of the encryption key length, except for at least the last subsample; a unitizing means for dividing the subsample to obtain units that are sized to fit into an MMTP packet and in which the scrambled portion in the MMTP packet is an integer multiple of the encryption key, except for at least the last unit; a scrambling means for scrambling a scrambled portion in the unit that is to be scrambled; a packetization means for storing the scrambled portion and the non-scrambled portion in separate MMTP packets when the unit includes a non-scrambled portion that is not subject to scrambling; A broadcast transmission device comprising:

2. the scrambling means includes an MMTP packet scrambling initial value setting means for setting an MMTP packet scrambling initial value which is a scrambling initial value on a unit basis, The packetization means generates a scrambled MMPT packet that includes the scrambled portion in a payload and includes the MMTP packet scrambling initial value in an extension header area.

2. The broadcast transmission device according to claim 1.

3. the MMTP packet scramble initial value setting means sets a sample scramble initial value, which is the scramble initial value of the sample, as the MMTP packet scramble initial value for a unit including a first scramble part for a plurality of units obtained by further dividing a plurality of sub-samples obtained by dividing the sample, and sets a value obtained by adding a predetermined value to the MMTP packet scramble initial value of the unit including the immediately preceding scramble part as the MMTP packet scramble initial value for each unit from the second onwards; The predetermined value is a value obtained by dividing the number of bytes of the scrambled part of the unit including the immediately preceding scrambled part by the number of bytes of the encryption key.

3. The broadcast transmission device according to claim 2.

4. The packetization means generates an unscrambled MMPT packet including the unscrambled portion in a payload as an MMTP packet separate from an MMTP packet storing the scrambled portion that has been scrambled.

4. The broadcast transmission device according to claim 1, wherein the first and second signals are transmitted to the first and second terminals.

5. a containerization unit for generating movie fragment meta information for containerizing one or more samples in a movie fragment unit in the ISO-BMFF format; the movie fragment meta information includes, for each sample constituting the group, a sample scramble initial value, information on the number of sub-samples constituting the sample, and information on the number of bytes of the unscrambled part and the scrambled part of each sub-sample constituting the sample; The packetization means generates an MMPT packet including the movie fragment meta information in a payload as an MMTP packet separate from the MMPT packet storing the scrambled portion that has been scrambled and the MMPT packet storing the unscrambled portion.

5. The broadcast transmission device according to claim 1, wherein the first and second signals are transmitted to the first and second terminals.

6. The scrambling means performs the scrambling in AES CTR mode.

6. The broadcast transmission device according to claim 1, wherein the first and second signals are transmitted to the first and second terminals.

7. A relay device for a digital broadcasting system using MMT as a multiplexing method, A separation means for extracting, from the received stream, an unscrambled MMTP packet storing an unscrambled portion of the subsample that is not subject to scrambling, and a scrambled MMTP packet storing a scrambled portion of the subsample; a restoration means for restoring scrambled content including the subsample from the unscrambled portion acquired from the unscrambled MMTP packet and the scrambled portion acquired from the scrambled MMTP packet; a transmitting means for transmitting the restored scrambled content to a communication terminal via a communication network without performing descrambling; A relay device comprising:

Images