Broadcast scrambling device and broadcast scrambling method

Abstract

In a broadcasting system using a hierarchical transmission method, scrambled signals are generated with a simple configuration. [Solution] The broadcast scrambling device is a broadcast scrambling device that encrypts content transmitted according to a hierarchical transmission method, and comprises a receiving unit that receives an unscrambled signal including the content, a scrambling unit that generates a scrambled signal in which the content transmitted at a weak hierarchical level is encrypted by performing scrambling processing on the unscrambled signal received by the receiving unit, and a transmitting unit that transmits the scrambled signal generated by the scrambling unit.

Description

Technical Field

[0001] The present disclosure relates to a broadcast scrambling apparatus and a broadcast scrambling method.

Background Art

[0002] In recent years, retransmission services for retransmitting digital broadcasts have become widespread. For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2020-10199) discloses the following IP retransmission apparatus. That is, the IP retransmission apparatus is an IP retransmission apparatus used in an IP retransmission system that retransmits digital broadcast signals of a plurality of channels received from an antenna to a plurality of receivers via an IP multicast network. The IP retransmission apparatus extracts SI information from the digital broadcast signal, stores the SI information in a packet in which an SI identification value is given to a part of the header information, and sends the packet to the IP multicast network together with the broadcast stream or separately from the broadcast stream.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In addition to retransmission services, an independent broadcast service for distributing the content of an independent broadcast channel using a hierarchical transmission method has become widespread. In the independent broadcast service, the content is encrypted, and a scrambled signal including the encrypted content is transmitted to a receiver at a user's home. In a broadcast system using a hierarchical transmission method, a technology capable of generating a scrambled signal with a simple configuration is desired.

[0005] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a broadcast scrambling device and a broadcast scrambling method that can generate scrambled signals with a simple configuration in a broadcasting system using a hierarchical transmission method. [Means for solving the problem]

[0006] The broadcast scrambling device of this disclosure is a broadcast scrambling device for encrypting content transmitted according to a hierarchical transmission scheme, comprising: a receiving unit for receiving an unscrambled signal including the content; a scrambling unit for generating a scrambled signal in which the content transmitted at a weak hierarchical level is encrypted by performing scrambling processing on the unscrambled signal received by the receiving unit; and a transmitting unit for transmitting the scrambled signal generated by the scrambling unit.

[0007] One aspect of this disclosure can be implemented not only as a broadcast scrambling device equipped with such characteristic processing steps, but also as a program for causing a computer to execute such characteristic processing steps. Furthermore, one aspect of this disclosure can be implemented as a semiconductor integrated circuit that implements part or all of the broadcast scrambling device, or as a system including the broadcast scrambling device. [Effects of the Invention]

[0008] According to this disclosure, scrambled signals can be generated in a broadcasting system using a hierarchical transmission method with a simple configuration. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a diagram showing the configuration of a broadcasting system according to an embodiment of the present disclosure. [Figure 2] Figure 2 shows the structure of a broadcast TS packet generated by an encoding device according to an embodiment of the present disclosure. [Figure 3]Figure 3 shows the configuration of a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 4] Figure 4 shows an example of a TS packet Pt extracted by a weak-level extraction unit in a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 5] Figure 5 shows an example of a TS packet Pt output by the NULL blocking unit in a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 6] Figure 6 shows an example of a TS packet Pt output by the PMT blocking unit in a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 7] Figure 7 shows an example of a TS packet Pt stored in the multiplexing section of a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 8] Figure 8 shows an example of a scrambled signal generated by a weak-level insertion unit in a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 9] Figure 9 shows another example of a TS packet Pt extracted by the weak-level extraction unit in a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 10] Figure 10 shows another example of a TS packet Pt output by the NULL blocking unit in a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 11] Figure 11 shows another example of a TS packet Pt output by the PMT blocking unit in a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 12] Figure 12 shows another example of a TS packet Pt stored in the multiplexing section of a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 13] Figure 13 shows another example of a scrambled signal generated by a weak-hierarchy insertion unit in a broadcast scrambling device according to an embodiment of the present disclosure. [Figure 14]Figure 14 is a flowchart illustrating an example of the operating procedure when a broadcast scrambling device according to an embodiment of the present disclosure transmits a scrambled signal. [Figure 15] Figure 15 is a flowchart illustrating an example of the operating procedure when a broadcast scrambling device according to an embodiment of the present disclosure performs scrambling processing. [Modes for carrying out the invention]

[0010] First, the embodiments of this disclosure will be listed and explained. (1) A broadcast scrambling device according to an embodiment of the present disclosure is a broadcast scrambling device for encrypting content transmitted in accordance with a hierarchical transmission method, comprising: a receiving unit for receiving an unscrambled signal including the content; a scrambling unit for generating a scrambled signal in which the content transmitted at a weak hierarchical level is encrypted by performing scrambling processing on the unscrambled signal received by the receiving unit; and a transmitting unit for transmitting the scrambled signal generated by the scrambling unit.

[0011] In this configuration, by scrambling the unscrambled signal and generating and transmitting a scrambled signal in which the content transmitted at the weaker layer is encrypted, it is possible to selectively encrypt the weaker layer content that needs to be encrypted and generate a scrambled signal without performing encryption or other processing on content assigned to layers other than the weaker layer. Therefore, since it is not necessary to generate and update ISDB-T (Integrated Services Digital Broadcasting for Terrestrial) information for content assigned to layers other than the weaker layer, the scale of the circuit for scrambling can be reduced, and the transmission delay of the content can be reduced. Thus, in broadcast systems using a layered transmission method, scrambled signals can be generated with a simple configuration.

[0012] (2) In the above (1), the receiving unit may receive the non-scramble signal which is a stream of packets including the content, and the scrambling unit may generate a second packet obtained by encrypting a first packet transmitted in a weak layer among the packets, and generate the scramble signal including the second packet transmitted in the weak layer instead of the first packet.

[0013] With such a configuration, while replacing the first packet transmitted in the weak layer with the encrypted second packet, it is possible to generate a scramble signal using the packets assigned to the layers other than the weak layer as they are. Therefore, the scale of the circuit for performing the scramble process can be made smaller, and the transmission delay of the content can be reduced.

[0014] (3) In the above (2), the scrambling unit may generate a scramble signal in which the pattern of the transmission order of a plurality of the packets transmitted in the weak layer and a plurality of the packets not transmitted in the weak layer is the same as that of the non-scramble signal.

[0015] With such a configuration, for example, it is possible to generate a scramble signal in which the transmission rate of the packets for each layer is equal to that of the non-scramble signal.

[0016] (4) In the above (2) or (3), the scrambling unit may generate an ECM packet including a scramble key for decrypting the second packet, an EMM packet including a working key for decrypting the ECM packet, and a PMT packet including descriptor information regarding the scramble key, and generate the scramble signal further including the generated ECM packet, EMM packet, and PMT packet.

[0017] With such a configuration, these packets required with the encryption of the content can be efficiently inserted into the scramble signal.

[0018] (5) In (4) above, some of the plurality of first packets in the unscrambled signal may be NULL packets, and the scrambling unit may generate the scrambled signal including the ECM packet, the EMM packet and the PMT packet instead of the NULL packet.

[0019] This configuration allows packets such as ECM packets to be inserted into the scrambled signal without changing the transmission rate of packets transmitted at the weaker layer.

[0020] (6) In any of (2) to (5) above, the scrambling unit may detect the number of layers in the layered transmission method and identify the first packet among the packets based on the detection result of the number of layers.

[0021] This configuration allows for the automatic identification of packets transmitted at the weaker layer, enabling flexible scrambling in response to various layered transmission systems used in broadcasting.

[0022] (7) A broadcast scrambling method according to an embodiment of the present disclosure is a broadcast scrambling method in a broadcast scrambling device that encrypts content transmitted in accordance with a hierarchical transmission scheme, comprising the steps of: receiving an unscrambled signal including the content; generating a scrambled signal in which the content transmitted at a weak hierarchical level is encrypted by performing scrambling processing on the received unscrambled signal; and transmitting the generated scrambled signal.

[0023] In this way, by scrambling the unscrambled signal and generating and transmitting a scrambled signal in which the content transmitted in the weak layer is encrypted, it is possible to selectively encrypt the weak layer content that needs to be encrypted and generate a scrambled signal without performing encryption or other processing on content assigned to layers other than the weak layer. Therefore, since it is not necessary to generate and update ISDB-T information for content assigned to layers other than the weak layer, the scale of the circuit for scrambling can be reduced, and the transmission delay of content can be reduced. Consequently, in broadcast systems using a layered transmission method, scrambled signals can be generated with a simple configuration.

[0024] Embodiments of this disclosure will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any way.

[0025] [Configuration and Basic Operation] Figure 1 is a diagram showing the configuration of a broadcasting system according to an embodiment of the present disclosure. Referring to Figure 1, the broadcasting system 401 comprises a broadcast scrambling device 101, an encoding device 111, a transmitting device 121, a plurality of retransmitting devices 131, and a multiplexer 141. The broadcast scrambling device 101, encoding device 111, transmitting device 121, retransmitting devices 131, and multiplexer 141 are installed in the cable television station building 201. The broadcasting system 401 may be configured to have one retransmitting device 131, or it may be configured not to have a retransmitting device 131. Furthermore, the broadcasting system 401 may be configured to have multiple sets of the broadcast scrambling device 101, encoding device 111, and transmitting device 121.

[0026] For example, the broadcasting system 401 transmits content to a Set-Top Box (STB) 351 installed in the user's home via a cable television (CATV) network 251, in accordance with ISDB-T. The content includes, for example, audio information, video information, and PSI (Program Specific Information) information. The content includes PSI information such as a Program Association Table (PAT) and a Program Map Table (PMT).

[0027] The retransmission device 131 retransmits terrestrial digital broadcasts. More specifically, each retransmission device 131 is assigned a terrestrial digital broadcast channel. The retransmission device 131 receives the RF (Radio Frequency) band broadcast signal corresponding to the assigned channel via an antenna. The retransmission device 131 transmits the received broadcast signal to the STB 351 via the multiplexer 141 and the CATV network 251. Alternatively, the retransmission device 131 may be configured to perform frequency conversion on the received broadcast signal and transmit the frequency-converted broadcast signal.

[0028] The encoding device 111 generates an unscrambled signal containing content to be transmitted according to a hierarchical transmission scheme and transmits the generated unscrambled signal to the broadcast scrambling device 101. For example, the encoding device 111 generates an unscrambled signal which is a stream of TS packets Pt containing content and transmits it to the broadcast scrambling device 101. A TS packet Pt is a 188-byte packet containing a 4-byte header and a 184-byte payload.

[0029] More specifically, the encoding device 111 acquires content corresponding to, for example, a local broadcast channel at a cable television station, and compresses and encodes the audio and video information contained in the acquired content to generate multiple TS packets Pt containing audio ES (Elementary Stream) and multiple TS packets Pt containing video ES. The encoding device 111 also generates multiple TS packets Pt containing PSI information for the local broadcast channel.

[0030] Furthermore, the encoding device 111 generates IIP (ISDB-T_Information_Packet) information indicating the number of segments in each layer of the hierarchical transmission scheme, and generates a TS packet Pt containing the generated IIP information. The PID of the TS packet Pt containing the IIP information is "0x1FF0". The number starting with "0x" means that the numbers after "0x" are represented in hexadecimal.

[0031] Figure 2 shows the structure of a broadcast TS packet generated by an encoding device according to an embodiment of the present disclosure. Referring to Figure 2, the encoding device 111 adds 16 bytes of dummy bytes Dm to the generated TS packet Pt. The dummy bytes Dm include 8 bytes of ISDB-T information and 8 bytes of parity. Hereinafter, the TS packet Pt with the dummy bytes Dm added will also be referred to as a broadcast TS packet Pbr.

[0032] The ISDB-T information in the dummy byte Dm contains 4 bits of layer information (layer_Indicator) that indicates the layer to which the corresponding TS packet Pt is transmitted. For example, the layer indicated by the layer information is defined by ARIB (Association of Radio Industries and Businesses) and is one of the following: Layer A, Layer B, Layer C, or Invalid Layer.

[0033] In layered transmission with "3" layers, TS packets Pt are transmitted using the strong layer, the middle layer, and the weak layer. The required Carrier-to-Noise (CN) ratio decreases in the order of strong, middle, and weak layers. In layered transmission with "3" layers, layer A is the strong layer, layer B is the middle layer, and layer C is the weak layer.

[0034] Furthermore, in layered transmission with "2" layers, TS packets Pt are transmitted using a strong layer and a weak layer. In layered transmission with "2" layers, layer A is the strong layer and layer B is the weak layer. In this case, for example, layer A is used for 1-segment broadcasting and layer B is used for full-segment broadcasting.

[0035] Furthermore, in layered transmission with a layer count of "1," TS packets Pt are transmitted using the weak layer. In layered transmission with a layer count of "1," layer A is the weak layer. In this case, for example, layer A is used for full-segment broadcasting.

[0036] Referring again to Figure 1, the encoding device 111 transmits the unscrambled signal, which is a stream of TS packets Pt, to the broadcast scrambling device 101. For example, the unscrambled signal is an ASI (Asynchronous Serial Interface) signal.

[0037] The broadcast scrambling device 101 encrypts the content transmitted according to the hierarchical transmission scheme. More specifically, the broadcast scrambling device 101 generates a scrambled signal by scrambling the unscrambled signal received from the encoding device 111. The broadcast scrambling device 101 transmits the generated scrambled signal to the transmitting device 121.

[0038] The transmitting device 121 generates an RF band broadcast signal by modulating the scrambled signal received from the broadcast scrambling device 101, for example, by OFDM modulation. The transmitting device 121 transmits the generated broadcast signal to the STB 351 via the multiplexer 141 and the CATV network 251.

[0039] [assignment] When encrypting content transmitted according to a hierarchical transmission method, it is not necessary to encrypt TS packets Pt transmitted at the strong layer or TS packets Pt at the invalid layer, while encrypting TS packets Pt transmitted at the weak layer.

[0040] Conventional broadcast scrambling devices, during the scrambling process, acquire TS packets Pt from all broadcast TS packets Pbr included in the unscrambled signal, and selectively encrypt TS packets Pt transmitted at the weaker layer among the acquired TS packets Pt. However, conventional broadcast scrambling devices also need to generate dummy bytes Dm, multiplex the dummy bytes Dm onto the encrypted TS packets Pt, and multiplex the dummy bytes Dm onto TS packets Pt that do not need to be encrypted, which increases the circuit size and can cause transmission delays.

[0041] Therefore, the broadcast scrambling device 101 according to the embodiment of this disclosure solves the above problem with the following configuration.

[0042] (Broadcast scrambling device) Figure 3 is a diagram showing the configuration of a broadcast scrambling device according to an embodiment of the present disclosure. Referring to Figure 3, the broadcast scrambling device 101 comprises a receiving unit 10, a scrambling unit 20, a transmitting unit 30, a key acquisition unit 40, and a storage unit 50. The scrambling unit 20 includes a weak hierarchical extraction unit 21, a NULL blocking unit 22, a PMT blocking unit 23, an encryption unit 24, a PMT editing unit 25, a NULL generation unit 26, an ECM / EMM generation unit 27, a multiplexing unit 28, and a weak hierarchical insertion unit 29. The multiplexing unit 28 has buffers 28A, 28B, 28C, and 28D. Some or all of the receiving unit 10, the scrambling unit 20, the transmitting unit 30, and the key acquisition unit 40 are implemented by a processing circuit (Circuitry) including, for example, one or more processors. The storage unit 50 is, for example, a non-volatile memory included in the above processing circuit.

[0043] The memory unit 50 stores multiple work keys Kw and multiple scramble keys Ks. For example, the work keys Kw and scramble keys Ks in the memory unit 50 are each acquired by the key acquisition unit 40 at timings according to a predetermined update cycle.

[0044] The key acquisition unit 40 acquires the work key Kw and the scrambled key Ks from the storage unit 50. The key acquisition unit 40 outputs the acquired work key Kw and scrambled key Ks to the ECM / EMM generation unit 27, and also outputs the acquired scrambled key Ks to the encryption unit 24. The key acquisition unit 40 randomly acquires the scrambled key Ks from the storage unit 50 at a predetermined update cycle and outputs the acquired scrambled key Ks to the ECM / EMM generation unit 27 and the encryption unit 24. The key acquisition unit 40 randomly acquires the work key Kw from the storage unit 50 at a predetermined update cycle and outputs the acquired work key Kw to the ECM / EMM generation unit 27.

[0045] Furthermore, the key acquisition unit 40 outputs descriptor information F1 relating to the scrambled key Ks to the PMT editing unit 25 and the ECM / EMM generation unit 27. For example, the descriptor information F1 is information indicating the PID of the TS packet Pt in which the ECM containing the scrambled key Ks is stored.

[0046] The receiving unit 10 receives an unscrambled signal containing content. More specifically, the receiving unit 10 receives an unscrambled signal, which is a stream of TS packets Pt containing content, from the encoding device 111. The receiving unit 10 outputs the received unscrambled signal to the scrambling unit 20.

[0047] The scrambling unit 20 generates a scrambled signal in which the content transmitted at the weak layer is encrypted by performing scrambling processing on the unscrambled signal received by the receiving unit 10. More specifically, the scrambling unit 20 generates a scrambled signal by encrypting the unscrambled signal received from the receiving unit 10 using the scrambling key Ks received from the key acquisition unit 40. The scrambling unit 20 outputs the generated scrambled signal to the transmitting unit 30.

[0048] The transmitting unit 30 transmits the scrambled signal generated by the scrambling unit 20. More specifically, the transmitting unit 30 encodes the scrambled signal received from the scrambling unit 20 using Reed-Solomon coding and transmits the encoded scrambled signal to the transmitting device 121.

[0049] (Scrambling) The weak layer extraction unit 21 extracts TS packets Pt transmitted at the weak layer from the unscrambled signal received from the receiving unit 10. For example, the weak layer extraction unit 21 detects the number of layers in the layered transmission system, identifies the TS packets Pt transmitted at the weak layer among the TS packets Pt based on the detection result of the number of layers, and extracts the identified TS packets Pt.

[0050] More specifically, the weak hierarchical extraction unit 21 detects TS packets Pt containing IIP information based on the PID of the TS packets Pt included in the unscrambled signal, and obtains IIP information from the detected TS packets Pt. Based on the obtained IIP information, the weak hierarchical extraction unit 21 determines the number of hierarchical layers in the hierarchical transmission scheme.

[0051] Specifically, the weak hierarchical extraction unit 21 determines that the number of hierarchical levels is "1" if the number of segments in hierarchical level B and hierarchical level C are "other than 1 to 13" and the number of segments in hierarchical level A is 1 or more. On the other hand, the weak hierarchical extraction unit 21 determines that the number of hierarchical levels is "2" if the number of segments in hierarchical level C are "other than 1 to 13" and the number of segments in hierarchical level A and hierarchical level B are 1 or more. On the other hand, the weak hierarchical extraction unit 21 determines that the number of hierarchical levels is "3" if the number of segments in hierarchical level A, hierarchical level B, and hierarchical level C are 1 or more.

[0052] As an example, the weak layer extraction unit 21 determines, based on the IIP information, that the number of layers in the hierarchical transmission method is "1". As described above, in hierarchical transmission with a number of layers of "1", layer A is the weak layer.

[0053] Figure 4 shows an example of a TS packet Pt extracted by a weak layer extraction unit in a broadcast scrambling device according to an embodiment of the present disclosure. In Figure 4, "A" represents TS packet PtA and "N" represents TS packet PtN. The same applies to subsequent figures. Referring to Figure 4, the unscrambled signal includes TS packets PtA and PtN when the number of layers is "1". TS packet PtA is a TS packet Pt transmitted at layer A. TS packet PtN is a TS packet Pt assigned to an invalid layer that is not transmitted at any of layers A, B, or C. When the number of layers is "1", TS packet PtA is an example of the first packet.

[0054] If the weak layer extraction unit 21 determines that the number of layers is "1", it extracts TS packet PtA from among the multiple broadcast TS packets Pbr included in the unscrambled signal and outputs the extracted TS packet PtA to the NULL blocking unit 22.

[0055] Figure 5 shows an example of a TS packet Pt output by a NULL blocking unit in a broadcast scrambling device according to an embodiment of the present disclosure. Referring to Figure 5, the NULL blocking unit 22 removes NULL packets Pnu from the TS packets PtA received from the weak hierarchical extraction unit 21. More specifically, some of the multiple TS packets PtA in the unscrambled signal are NULL packets Pnu. The NULL blocking unit 22 determines whether a TS packet PtA is a NULL packet Pnu based on the PID of the TS packet PtA.

[0056] The NULL blocking unit 22 discards NULL packets Pnu from the TS packets PtA received from the weak hierarchical extraction unit 21. On the other hand, the NULL blocking unit 22 outputs TS packets PtA other than NULL packets Pnu from the TS packets PtA received from the weak hierarchical extraction unit 21 to the PMT blocking unit 23.

[0057] The PMT blocking unit 23 extracts PMT packet Pp1, which is a TS packet PtA containing PMT, from among the TS packets PtA received from the NULL blocking unit 22. More specifically, the PMT blocking unit 15 extracts TS packets PtA containing PAT based on the PID of the TS packet PtA received from the NULL blocking unit 22. Here, the PID of a TS packet Pt containing PAT is "0x0000". The PMT blocking unit 23 obtains PAT from the extracted TS packet PtA and obtains PIDpmt, which is the PID of PMT packet Pp1, by analyzing the obtained PAT. Once the PMT blocking unit 23 obtains PIDpmt, it starts extracting PMT packet Pp1 based on the obtained PIDpmt.

[0058] Figure 6 shows an example of a TS packet Pt output by a PMT blocking unit in a broadcast scrambling device according to an embodiment of the present disclosure. Referring to Figure 6, the PMT blocking unit 23 determines that TS packet PtB, among the TS packets PtA received from the NULL blocking unit 22, whose PID matches PIDpmt, is PMT packet Pp1. The PMT blocking unit 23 outputs PMT packet Pp1 from the TS packets PtA received from the NULL blocking unit 22 to the PMT editing unit 25. On the other hand, the PMT blocking unit 23 outputs TS packets PtA other than PMT packet Pp1 from the TS packets PtA received from the NULL blocking unit 22 to the encryption unit 24.

[0059] Figure 7 shows an example of a TS packet Pt stored in the multiplexing unit of a broadcast scrambling device according to an embodiment of the present disclosure. Referring to Figure 7, the encryption unit 24 generates a TS packet Psc in which a TS packet PtA transmitted at the weak layer of the TS packet Pt included in the unscrambled signal is encrypted. The TS packet Psc is an example of a second packet. More specifically, the encryption unit 24 generates the TS packet Psc by encrypting the TS packet PtA received from the PMT blocking unit 23 using the latest scrambling key Ks received from the key acquisition unit 40. The encryption unit 24 stores the generated TS packet Psc in the buffer 28A of the multiplexing unit 28.

[0060] The PMT editing unit 25 generates a PMT packet Pp2, which is a TS packet Pt containing descriptor information F1 related to the scramble key Ks. More specifically, the PMT editing unit 25 receives a PMT packet Pp1 from the PMT blocking unit 23 and generates a PMT packet Pp2 in which the descriptor information F1 received from the key acquisition unit 40 is added to the PMT in the received PMT packet Pp1. The PMT editing unit 25 generates a PMT packet Pp2 each time it receives a PMT packet Pp1 from the PMT blocking unit 23 and stores the generated PMT packet Pp2 in buffer 28B.

[0061] The NULL generation unit 26 generates NULL packets Pnu, which are TS packets Pt in which no information is stored in the payload, at generation timings according to a predetermined generation cycle, and stores the generated NULL packets Pnu in buffer 28C. The NULL generation unit 26 may also generate and store NULL packets Pnu in buffer 28C irregularly, so that the number of NULL packets Pnu in buffer 28C is equal to or greater than a predetermined value.

[0062] The ECM / EMM generation unit 27 generates an ECM packet Pec containing a scramble key Ks for decrypting the TS packet Psc. More specifically, the ECM / EMM generation unit 27 generates an ECM containing the scramble key Ks received from the key acquisition unit 40 at an ECM transmission timing according to a predetermined transmission period C1. The ECM / EMM generation unit 27 generates an ECM packet Pec, which is a TS packet Pt containing the generated ECM, and stores it in the buffer 28D.

[0063] Furthermore, the ECM / EMM generation unit 27 generates an EMM packet Pem containing a work key Kw for decrypting the ECM packet Pec. More specifically, the ECM / EMM generation unit 27 generates an EMM containing the work key Kw received from the key acquisition unit 40 at an EMM transmission timing according to a predetermined transmission period C2. The ECM / EMM generation unit 27 generates an EMM packet Pem, which is a TS packet Pt containing the generated EMM, and stores it in the buffer 28D.

[0064] The weak layer insertion unit 29 generates a scrambled signal that includes TS packet Psc, ECM packet Pec, EMM packet Pem, and PMT packet Pp2 transmitted at the weak layer, instead of TS packet PtA. More specifically, the weak layer insertion unit 29 generates a scrambled signal by replacing TS packet PtA, which is included in the unscrambled signal received from the receiving unit 10, with TS packet Psc, ECM packet Pec, EMM packet Pem, or PMT packet Pp2 stored in the multiplexing unit 28.

[0065] For example, the weak hierarchical insertion unit 29 generates a scrambled signal that includes an ECM packet, an ECM packet Pec, an EMM packet Pem, or a PMT packet Pp2 instead of a NULL packet Pnu. More specifically, the weak hierarchical insertion unit 29 replaces the NULL packet Pnu in the unscrambled signal with an ECM packet Pec, an EMM packet Pem, or a PMT packet Pp2.

[0066] Figure 8 shows an example of a scrambled signal generated by a weak hierarchical insertion unit in a broadcast scrambling device according to an embodiment of the present disclosure. Referring to Figure 8, the weak hierarchical insertion unit 29 acquires IIP information from TS packets Pt in the same manner as the weak hierarchical extraction unit 21, and determines that the number of hierarchical layers in the hierarchical transmission system is "1" based on the acquired IIP information. The weak hierarchical insertion unit 29 then refers to the hierarchical information stored in the ISDB-T information in the dummy byte Dm included in the unscrambled signal received from the receiving unit 10, and removes TS packet PtA from the TS packets Pt included in the unscrambled signal.

[0067] The weak layer insertion unit 29 obtains a TS packet Pt from the multiplexing unit 28 and generates a scrambled signal by inserting the TS packet Pt obtained from the multiplexing unit 28 in place of the removed TS packet PtA. In other words, the weak layer insertion unit 29 generates a scrambled signal by adding the dummy byte Dm that was attached to the removed TS packet PtA to the TS packet Pt obtained from the multiplexing unit 28. The weak layer insertion unit 29 outputs the generated scrambled signal to the transmission unit 30.

[0068] For example, the weak layer insertion unit 29 generates a scrambled signal in which the transmission order pattern of multiple TS packets PtA and multiple TS packets PtN that are not transmitted in the weak layer is the same as that of the unscrambled signal.

[0069] More specifically, the weak layer insertion unit 29 obtains the same number of TS packets Pt from the multiplexing unit 28 as the number of TS packets PtA removed from the unscrambled signal and inserts them into the unscrambled signal. Specifically, each time a TS packet PtA is removed from the unscrambled signal, the weak layer insertion unit 29 obtains one of the following TS packets Pt from the multiplexing unit 28: TS packet Psc, ECM packet Pec, EMM packet Pem, and PMT packet Pp2, and inserts the obtained TS packet Pt in place of the removed TS packet PtA.

[0070] If the TS packet Psc, ECM packet Pec, EMM packet Pem, and PMT packet Pp2 are not stored in the multiplexing unit 28, the weak-layer insertion unit 29 retrieves the NULL packet Pnu from the buffer 28C and inserts the NULL packet Pnu in place of the removed TS packet PtA.

[0071] (Other examples of scrambling) For example, the weak hierarchical extraction unit 21 determines, based on the IIP information, that the number of hierarchical layers in the hierarchical transmission system is "2". As described above, in hierarchical transmission with "2" layers, layer A is the strong hierarchical layer and layer B is the weak hierarchical layer.

[0072] Figure 9 shows another example of a TS packet Pt extracted by a weak layer extraction unit in a broadcast scrambling device according to an embodiment of the present disclosure. In Figure 9, "B" indicates TS packet PtB. The same applies to subsequent figures. Referring to Figure 9, the unscrambled signal includes TS packets PtA, PtB, and PtN when the number of layers is "2". TS packet PtB is a TS packet Pt transmitted at layer B. When the number of layers is "2", TS packet PtB is an example of the first packet.

[0073] If the weak layer extraction unit 21 determines that the number of layers is "2", it extracts TS packet PtB from among the multiple broadcast TS packets Pbr included in the unscrambled signal and outputs the extracted TS packet PtB to the NULL blocking unit 22.

[0074] Figure 10 shows another example of a TS packet Pt output by the NULL blocking unit in a broadcast scrambling device according to an embodiment of the present disclosure. Referring to Figure 10, the NULL blocking unit 22 removes NULL packets Pnu from the TS packets PtB received from the weak hierarchical extraction unit 21. More specifically, some of the multiple TS packets PtB in the unscrambled signal are NULL packets Pnu. The NULL blocking unit 22 discards the NULL packets Pnu from the TS packets PtB received from the weak hierarchical extraction unit 21. On the other hand, the NULL blocking unit 22 outputs the TS packets PtB other than NULL packets Pnu from the TS packets PtB received from the weak hierarchical extraction unit 21 to the PMT blocking unit 23.

[0075] Figure 11 shows another example of a TS packet Pt output by the PMT blocking unit in a broadcast scrambling device according to an embodiment of the present disclosure. Referring to Figure 11, the PMT blocking unit 23 extracts PMT packet Pp1, which is a TS packet PtB containing PMT, from among the TS packets PtB received from the NULL blocking unit 22. More specifically, the PMT blocking unit 23 outputs PMT packet Pp1 from the TS packets PtB received from the NULL blocking unit 22 to the PMT editing unit 25. On the other hand, the PMT blocking unit 23 outputs TS packets PtB other than PMT packet Pp1 from the TS packets PtB received from the NULL blocking unit 22 to the encryption unit 24.

[0076] Figure 12 shows another example of a TS packet Pt stored in the multiplexer in a broadcast scrambling device according to an embodiment of the present disclosure. Referring to Figure 12, the encryption unit 24 generates a TS packet Psc in which a TS packet PtB transmitted in the weak layer of the TS packet Pt included in the unscrambled signal is encrypted. More specifically, the encryption unit 24 generates a TS packet Psc by encrypting the TS packet PtB received from the PMT blocking unit 23 using the latest scrambling key Ks received from the key acquisition unit 40. The encryption unit 24 stores the generated TS packet Psc in the buffer 28A in the multiplexer 28.

[0077] Figure 13 shows another example of a scrambled signal generated by the weak hierarchical insertion unit in a broadcast scrambling device according to an embodiment of the present disclosure. Referring to Figure 13, the weak hierarchical insertion unit 29 acquires IIP information from TS packets Pt in the same manner as the weak hierarchical extraction unit 21, and determines that the number of hierarchical layers in the hierarchical transmission system is "2" based on the acquired IIP information. The weak hierarchical insertion unit 29 then refers to the hierarchical information stored in the ISDB-T information in the dummy byte Dm included in the unscrambled signal received from the receiving unit 10, and removes TS packet PtB from the TS packets Pt included in the unscrambled signal.

[0078] The weak layer insertion unit 29 obtains a TS packet Pt from the multiplexing unit 28 and generates a scrambled signal by inserting the TS packet Pt obtained from the multiplexing unit 28 in place of the removed TS packet PtB. In other words, the weak layer insertion unit 29 generates a scrambled signal by adding the dummy byte Dm that was attached to the removed TS packet PtB to the TS packet Pt obtained from the multiplexing unit 28. The weak layer insertion unit 29 outputs the generated scrambled signal to the transmission unit 30.

[0079] [Operation Flow] Figure 14 is a flowchart illustrating an example of the operating procedure when a broadcast scrambling device according to an embodiment of the present disclosure transmits a scrambled signal.

[0080] Referring to Figure 14, first, the broadcast scrambling device 101 receives an unscrambled signal from the encoding device 111 (step S11).

[0081] Next, the broadcast scrambling device 101 generates a scrambled signal in which the content transmitted at the weak layer is encrypted by performing scrambling processing on the unscrambled signal (step S12).

[0082] Next, the broadcast scrambling device 101 transmits the generated scrambled signal to the transmitting device 121 (step S13).

[0083] Figure 15 is a flowchart illustrating an example of the operation procedure when a broadcast scrambling device according to an embodiment of the present disclosure performs scrambling. Figure 15 shows the details of the process in step S12 in Figure 14.

[0084] Referring to Figure 15, first, the scrambling unit 20 in the broadcast scrambling device 101 detects the number of layers in the hierarchical transmission system. For example, the scrambling unit 20 determines that the number of layers in the hierarchical transmission system is "1" based on the IIP information contained in the unscrambled signal (step S21).

[0085] Next, the scrambling unit 20 extracts the TS packet PtA transmitted at the weak layer from among the multiple broadcast TS packets Pbr included in the unscrambled signal (step S22).

[0086] Next, the scrambling unit 20 removes NULL packets Pnu from the extracted TS packets PtA (step S23).

[0087] Next, the scrambling unit 20 extracts the PMT packet Pp1 from the TS packet PtA from which the NULL packet Pnu has been removed (step S24).

[0088] Next, the scrambling unit 20 generates a TS packet Psc by encrypting the TS packet PtA, excluding the PMT packet Pp1, using the scrambling key Ks (step S25).

[0089] Next, the scrambling unit 20 generates a PMT packet Pp2 in which descriptor information F1 is added to the PMT in the extracted PMT packet Pp1 (step S26).

[0090] Next, the scrambling unit 20 generates a NULL packet Pnu, an ECM packet Pec, and an EMM packet Pem (step S27).

[0091] Next, the scrambling unit 20 removes TS packet PtA from the TS packets Pt included in the unscrambled signal (step S28).

[0092] Next, the scrambling unit 20 generates a scrambled signal by inserting TS packet Psc, ECM packet Pec, EMM packet Pem, and PMT packet Pp2 in place of the removed TS packet PtA (step S29).

[0093] In the broadcast scrambling device 101 according to the embodiment of this disclosure, the scrambling unit 20 is configured to generate a scrambled signal that includes TS packets Psc instead of TS packets PtA transmitted at the weak layer, but it is not limited to this configuration. The scrambling unit 20 may also be configured to generate a scrambled signal by adding TS packets Psc to the unscrambled signal without removing at least some of the TS packets PtA contained in the unscrambled signal.

[0094] Furthermore, in the broadcast scrambling device 101 according to the embodiment of this disclosure, the scrambling unit 20 is configured to generate a scrambled signal in which the transmission order pattern of a plurality of TS packets PtA and a plurality of TS packets PtN that are not transmitted at the weak layer is the same as that of the unscrambled signal, but the invention is not limited to this configuration. The scrambling unit 20 may be configured to generate a scrambled signal in which the transmission order pattern is different from that of the unscrambled signal.

[0095] Furthermore, while the broadcast scrambling device 101 according to the embodiment of this disclosure has a configuration in which the scrambling unit 20 includes a PMT editing unit 25 and an ECM / EMM generation unit 27, it is not limited to this configuration. The scrambling unit 20 may also have a configuration that does not include at least one of the PMT editing unit 25 and the ECM / EMM generation unit 27. In this case, for example, a device other than the broadcast scrambling device 101 inserts an ECM packet Pec, an EMM packet Pem, and a PMT packet Pp2 into the scrambled signal generated by the broadcast scrambling device 101.

[0096] Furthermore, while the broadcast scrambling device 101 according to the embodiment of this disclosure is configured such that the scrambling unit 20 replaces NULL packets Pnu included in the unscrambled signal with ECM packets Pec, EMM packets Pem, or PMT packets Pp2, it is not limited to this configuration. The scrambling unit 20 may also be configured to replace TS packets PtA other than NULL packets Pnu included in the unscrambled signal with ECM packets Pec, EMM packets Pem, or PMT packets Pp2.

[0097] Furthermore, in the broadcast scrambling device 101 according to the embodiment of this disclosure, the scrambling unit 20 is configured to detect the number of layers in the hierarchical transmission system and to identify TS packets Pt transmitted at the weak layer among the TS packets Pt based on the detection result of the number of layers, but it is not limited to this. The scrambling unit 20 may also be configured to receive information indicating the number of layers in the hierarchical transmission system from the administrator of the broadcast scrambling device 101.

[0098] The embodiments described above should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0099] Each process (each function) of the above-described embodiment is implemented by a processing circuit (Circuitry) including one or more processors. The processing circuit may consist of one or more memories, various analog circuits, various digital circuits, etc., in addition to the one or more processors, as well as an integrated circuit. The one or more memories store programs (instructions) that cause the one or more processors to execute each of the above processes. The one or more processors may execute each of the above processes according to the programs read from the one or more memories, or they may execute each of the above processes according to logic circuits that have been pre-designed to execute each of the above processes. The processors may be various processors suitable for computer control, such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), and ASIC (Application Specific Integrated Circuit). Furthermore, the physically separated multiple processors may cooperate with each other to execute each of the above processes. For example, the processors installed in each of several physically separated computers may cooperate with each other via a network such as a LAN (Local Area Network), WAN (Wide Area Network), and the Internet to perform the above processes. The program may be installed in the memory via the network from an external server device, or it may be distributed on a recording medium such as a CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disk Read Only Memory), and semiconductor memory, and then installed in the memory from the recording medium.

[0100] The above description includes the following features. [Note 1] A broadcast scrambling device that encrypts content transmitted according to a hierarchical transmission method, A receiving unit that receives an unscrambled signal containing the aforementioned content, A scrambling unit generates a scrambled signal in which the content transmitted at the weak layer is encrypted by performing scrambling processing on the non-scrambled signal received by the receiving unit, The system comprises a transmitting unit that transmits the scrambled signal generated by the scrambling unit, The receiving unit receives the unscrambled signal, which is a stream of packets containing the content. The packet is accompanied by a dummy byte containing hierarchical information relating to the hierarchical layer to which the packet is transmitted. The scrambling unit extracts a first packet transmitted at the weakest layer of the packet, generates a second packet by encrypting the extracted first packet, and adds the dummy bytes that were attached to the first packet to the generated second packet, thereby providing a broadcast scrambling device.

[0101] [Note 2] A broadcast scrambling device that encrypts content transmitted according to a hierarchical transmission method, Equipped with a processing circuit, The aforementioned processing circuit is Receiving an unscrambled signal containing the aforementioned content, By performing scrambling processing on the received unscrambled signal, a scrambled signal is generated in which the content transmitted at the weak layer is encrypted. A broadcast scrambling device that transmits the generated scrambled signal. [Explanation of symbols]

[0102] 10 Receiver 20 Scramble Section 21 Weak hierarchy extraction part 22 NULL blocking section 23 PMT blocking part 24 Encryption section 25 PMT Editorial Department 26 NULL generation section 27 ECM / EMM generation section 28 Multiplex section 28A, 28B, 28C, 28D buffer 29. Weakly layered insertion section 30 Transmitter 40 Key acquisition part 50 Storage section 101 Broadcast scrambling device 111 Encoding device 121 Transmitter 131 Retransmission device 141 Multiplexer 201 Station Building 251 CATV network 351 STB 401 Broadcasting System PBR broadcast TS packet

Claims

1. A broadcast scrambling device that encrypts content transmitted according to a hierarchical transmission method, A receiving unit that receives an unscrambled signal containing the aforementioned content, A scrambling unit generates a scrambled signal in which the content transmitted at the weak layer is encrypted by performing scrambling processing on the non-scrambled signal received by the receiving unit, A broadcast scrambling device comprising: a transmitting unit that transmits the scrambled signal generated by the scrambling unit;

2. The receiving unit receives the unscrambled signal, which is a stream of packets containing the content. The broadcast scrambling device according to claim 1, wherein the scrambling unit generates a second packet in which the first packet transmitted at the weak layer of the packet is encrypted, and generates a scrambled signal that includes the second packet transmitted at the weak layer instead of the first packet.

3. The broadcast scrambling device according to claim 2, wherein the scrambling unit generates a scrambled signal in which the transmission order pattern of a plurality of packets transmitted at the weak layer and a plurality of packets not transmitted at the weak layer is the same as that of the unscrambled signal.

4. The broadcast scrambling device according to claim 2 or 3, wherein the scrambling unit generates an ECM packet containing a scrambling key for decoding the second packet, an EMM packet containing a work key for decoding the ECM packet, and a PMT packet containing descriptor information relating to the scrambling key, and further generates the scrambled signal comprising the generated ECM packet, the EMM packet, and the PMT packet.

5. A portion of the multiple first packets in the unscrambled signal is a NULL packet. The broadcast scrambling device according to claim 4, wherein the scrambling unit generates the scrambled signal, which includes the ECM packet, the EMM packet, and the PMT packet, instead of the NULL packet.

6. The broadcast scrambling device according to claim 2 or 3, wherein the scrambling unit detects the number of layers in a layered transmission system and identifies the first packet among the packets based on the detection result of the number of layers.

7. A broadcast scrambling method in a broadcast scrambling device that encrypts content transmitted according to a hierarchical transmission scheme, The steps include receiving an unscrambled signal containing the aforementioned content, The steps include: generating a scrambled signal in which the content transmitted at the weak layer is encrypted by performing scrambling processing on the received unscrambled signal; A broadcast scrambling method comprising the step of transmitting the generated scrambled signal.

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