JP2006323455A - Transmitting device and relay device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmitting device and a relay device which can transmit data in response to a transmission band on a network, information on a device connected to the network, and the status of a transmission medium. <P>SOLUTION: A hard disk recorder 2100 employs the transmission protocol of TCP/HTTP (SP3011) because it is connected to the relay device 2101 with a wired medium. The relay device 2101 is connected to a digital television 2102 through a radio medium, and accordingly uses the transmission protocol of UDP/RTP (SP3012). The hard disk recorder 2100 transmits encrypted content data by TCP/HTTP to the relay device 2101. The relay device 2101 converts the protocol for the received data from HTTP to RTP (SP3017), and transmits the data to the digital television 2102 by UDP. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transmission device and a relay device, and more particularly to a transmission device that transmits content and a relay device that relays content between the transmission device and the reception device.

  In recent years, with the advance of communication network technology, the improvement of the network environment at home has been remarkable. Conventionally, a service of about several Mbps using a telephone line has only been provided. However, recently, services with a transmission rate having an allowance of several tens of Mbps to several Gbps using a dedicated medium such as an optical cable are increasing.

  In addition, 10Base-T and 100Base-T wired Ethernet (registered trademark) communication functions having a high transmission rate and wireless communication functions based on wireless LAN standards such as IEEE802.11a, IEEE802.11b, and IEEE802.11g are provided. Digital home appliances are becoming popular. Thus, by using a medium having a high transmission rate at home, it is possible to view high-quality content data at any location in the home. As a result, HD (high-definition): high-definition, high-quality from the environment that could only be seen in SD (Standard-Definition) standard video (Resolution) Changes to an environment where high-quality images of the class can be seen. Further, not only video but also audio can be expanded from 2ch, 4ch to 5.1ch, and further to 7.2ch, etc., and an environment in which high-quality video and audio can be viewed is obtained.

  Being able to view content anywhere in the home means that the rooms are connected in a wired or wireless network environment and a home network is built. A typical communication protocol used in a home / outside network environment is IP (Internet Protocol). One of the upper protocols that secure the reliability of data transmission based on this IP protocol is TCP (Transmission Control Protocol). By this TCP, communication connection multiplexing, transfer error detection and correction, sequence control, and flow control are performed. Further, UDP (User Datagram Protocol) is also used as a higher-level protocol of IP. UDP is a connection-less protocol that multiplexes connections and detects transfer errors (optional) but is less reliable than TCP.

  In order to actually transmit data, a protocol higher than TCP or UDP is required. The upper protocol of TCP is HTTP (HyperText Transfer Protocol) for transmitting WWW data on the Internet. On the other hand, the upper protocol of UDP is RTP (Real-time Transport Protocol) that transmits video and audio in real time.

  These protocols are shown as basic network models in FIG. Reference numeral 104 denotes a wired / wireless interface standard, Ethernet (registered trademark), or the like belonging to the physical layer and the data link layer. Reference numeral 103 denotes an IP belonging to the network layer. Reference numeral 102 denotes a TCP belonging to the transport layer. Reference numeral 106 denotes a UDP that also belongs to the transport layer. Reference numeral 101 denotes HTTP belonging to the application layer. Reference numeral 105 denotes an RTP that also belongs to the application layer. A user API (application interface) 100 is defined above the application layer. In accordance with these rules, the transmission device transmits data through a socket interface according to a predetermined protocol. On the other hand, the receiving device receives data according to the protocol. Thereby, data communication is performed between the transmitting and receiving apparatuses.

  With the improvement of the network environment, it has become possible to send and receive high-quality content. However, since digital data is not deteriorated compared to analog data, it is extremely important to protect the copyright of the content. As a copyright protection technique for this purpose, a copy protection technique by DTLA (Digital Transmission Licensing) is known. In this system, copyright protection technology is applied to devices licensed from the company, and content cannot be played or copied by illegal devices. Digital devices having an IEEE 1394 interface using this technology have been commercialized. The products that have been commercialized are mutually authenticated and encrypted on the digital data transmission path. Recently, DTLA also published a specification for mounting DTCP (Digital Transmission Content Protection) technology on an IP protocol instead of on IEEE1394.

  Hereinafter, an outline of the DTCP technology will be described. In the first step, mutual authentication of devices is performed between a transmitting device and a receiving device that transmit content requiring copyright protection. In the second step, a unique common key that exists when content is transmitted between the transmitting device and the receiving device is calculated. In the third step, an encryption key for encrypting the content is created using the common key, the content copy restriction information, and the encryption key switching information, and the content is encrypted. To transmit. Note that device information distributed by DTLA is required for mutual authentication of devices in the first step.

  A CBC (Cipher Block Chaining) mode is adopted as a content encryption method on the IP protocol. This is to increase the strength of the AES-128 bit block encryption scheme. Packets for data transmission using UDP / RTP (meaning combined use of TCP protocol and HTTP protocol; the same applies hereinafter) and TCP / HTTP (meaning combined use of UDP protocol and RTP protocol applied hereinafter) The format is shown in FIG.

  When transmitting the content data 1500 using the UDP / RTP protocol, first, the content data 1500 is divided into blocks of a predetermined unit. Next, a PCP 1502A subjected to cryptographic processing is generated for each divided block. Further, an RTP header 1501 is added to each PCP 1502A. Then, the PCP 1502A with the RTP header 1501 added is sequentially transmitted.

  As described above, when content data is transmitted by the UDP / RTP protocol, a plurality of PCPs 1502A are generated. In addition to Encrypted Data 1506, which is encrypted data, information EMI 1503, NC 1504, and LEN 1505 necessary for the data encryption key are added to PCP 1502A. EMI 1503 is bit data indicating copyright information of content, NC 1504 is data indicating key update timing, and LEN 1505 is data indicating data size (Non-Patent Document 1).

  When transmitting the content data 1500 using the TCP / HTTP protocol, first, the content data 1500 is not divided and the entire content data is encrypted to create a PCP 1502B. Next, an HTTP header 1507 is added to the PCP 1502B. Then, the PCP 1502B with the HTTP header 1507 added is transmitted.

  FIG. 23 is a diagram showing an encryption mechanism in the CBC mode (Non-Patent Document 2). FIG. 23 shows an initialization vector value 1601, a plaintext 1602, an XOR operator 1605, an AES-128 encryption block 1603, an AES-128 decryption block 1606, and a ciphertext 1604. FIG. 23A shows a CBC mode at the time of encryption. FIG. 23B shows a CBC mode at the time of decoding.

  In the CBC mode, an XOR 1605 operation is performed on the plaintext N to be encrypted and the previously encrypted ciphertext N-1, and the result is encrypted by the AES-128 encryption block 1603. Is generated. Since there is no previous ciphertext block corresponding to the first plaintext 1, an XOR 1605 operation is performed on plaintext 1 by giving an initial vector value 1601. At the time of decryption, the ciphertext N to be decrypted is decrypted by the AES-128 decryption block 1606, and the XOR 1605 operation is performed on the processing result and the ciphertext N-1 to obtain the plaintext N. Therefore, the CBC mode is a process in which the result of encryption and decryption is propagated to the next stage process. Therefore, the encryption strength is high.

  Japanese Patent Application Laid-Open No. 2003-198638 (Patent Document 1) discloses that protocol conversion is performed between an external public line network that is an external network and an IP network that is an internal network.

Japanese Patent Laid-Open No. 2004-328706 (Patent Document 2) describes a control method and data format of a transmission / reception apparatus for mounting the DTCP technology on UDP / RTP.
JP 2003-198638 A JP 2004-328706 A DTCP Volume 1 Supplement E Mapping DTCP to IP, Version 1.0 (Informational Version) NIST Special Publication 800-38A 2001 Edition “Recommendation for Block Cipher Modes of Operation” Methods and Techniques Morris Dworkin

  In many homes, networks are formed by combining wired and wireless networks. However, because the bandwidth of the transmission rate is limited for each, from the viewpoint of transmission efficiency, the data transmission bandwidth is taken into consideration. Need to be transmitted. In particular, as the number of devices connected to the network in the home increases, it becomes necessary to effectively use the limited bandwidth. That is, there is a problem of effective use of bandwidth.

  Also, in the case of wired communication, errors and lost of data to be transmitted are unlikely to occur, but in the case of wireless communication, data errors and lost are likely to occur depending on the state of communication. Therefore, it is necessary to perform data transmission in consideration of the characteristics of these communication media. That is, there is a problem of data transmission utilizing the characteristics of the communication medium. In general, data is often transmitted using TCP / HTTP in the case of wired communication and using UDP / RTP in the case of wireless communication.

  As described above, there are many cases where a plurality of devices are connected to a network in a home, and a relay device exists between a transmission device and a reception device that transmit content. When transmitting content requiring copyright protection technology on a home network, the DTCP technology as described above is used. When copyright protection technology is required for content to be transmitted as in the DTCP technology, device information is installed in each relay device, or the encrypted content is decrypted by the relay device, and then encrypted again. For this reason, in the configuration disclosed in Patent Document 1, a delay occurs when the content on transmission is reproduced by the receiving device, and a buffer for decrypting the encryption is required.

  In the configuration disclosed in Patent Document 2, the data protocol cannot be converted according to the transmission path or the like. Therefore, it is necessary to use the same protocol between the transmission device and the relay device, and between the relay device and the reception device. Patent Document 2 does not specifically disclose a method for specifying a protocol for transmitting content.

  In addition, DTCP is a technique for determining device authentication and encryption methods between end-end terminals and transmitting encrypted content from the source device side to the sink device side, and converts the content data itself. It is not a thing. For this reason, when HTTP is selected by DTCP despite the presence of a communication medium that is likely to be lost in the middle of the transmission path, retransmission occurs and transmission efficiency deteriorates. On the other hand, RTP has lower transmission efficiency of the protocol itself than HTTP.

  Thus, even if an appropriate transmission protocol is determined between end-end terminals, if the communication medium changes in the middle of the route, the determined protocol may not necessarily be optimal for that medium. When the protocol is changed by the relay device, it is necessary to perform complicated processing such as decryption and re-encryption. However, conventionally, there has been no device that changes the protocol in consideration of the communication path and the like.

  The present invention has been conceived in view of such circumstances, and its purpose is to transmit data that can be transmitted in accordance with the transmission band on the network, information on devices connected to the network, and the status of the transmission medium. An object is to provide a device and a relay device.

  In order to achieve the above object, according to one aspect of the present invention, a transmission device including a plurality of protocols for transmitting content data to a reception device, based on device information of the reception device when transmitting content data And a protocol selection means for selecting a transmission protocol.

  According to another aspect of the present invention, the device information is information indicating presence / absence of a display function and a recording function.

  According to another aspect of the present invention, there is provided a transmitting device having a plurality of protocols for transmitting content data to a receiving device, and when transmitting content data, the transmission protocol is determined based on content data copy restriction information. Protocol selection means for selecting is provided.

  According to another aspect of the present invention, there is provided a transmission device having a plurality of protocols for transmitting content data to the reception device, and the content data is transmitted based on information indicating how to use the reception device. Protocol selection means for selecting a protocol is provided.

  According to another aspect of the present invention, the protocol selection unit selects a transmission protocol from an RTP protocol and an HTTP protocol.

  According to another aspect of the present invention, the content data types are a stream system and a stationary system.

  According to another aspect of the present invention, a relay device that relays data transmitted between a transmission device and a reception device, a protocol selection means for selecting a transmission protocol when transmitting content data, Protocol conversion means for converting the transmission protocol of the content data input from the transmission device to the transmission protocol selected by the protocol selection means, and output means for outputting the content data converted by the protocol conversion means to the reception device It is characterized by providing.

  According to another aspect of the present invention, storage means for storing data input from the transmission device and data stored in the storage means are defined by a transmission protocol selected by the protocol selection means. A data length determining means for determining whether or not the data length of the packet has been reached, and generating an output packet from the data stored in the storage means when the data length determining means determines that the data length has been reached Output packet generating means.

  According to another aspect of the present invention, a storage unit that stores data input from the transmission device and an input timing of the data, and whether a predetermined time has elapsed since the data was input from the transmission device A time determination means for determining the output packet, and an output packet generation means for generating an output packet from the data stored in the storage means when the time determination means determines that the predetermined time has elapsed. To do.

  According to another aspect of the present invention, there is provided a relay device that relays data transmitted between a transmission device and a reception device, and an encrypted packet header encrypted with a predetermined encryption method and encryption Including protocol conversion means for converting packet data of the first protocol input from the transmission device to packet data of the second protocol, the protocol conversion means comprising: An extension header including an extension bit and a head flag, a padding flag, and a padding length is added to the header, and only the length of the data in the first packet differs from the head of the data in the second packet. The same encryption header is added, the data in the first packet is subdivided, and the data is loaded separately into the data in the second packet.

  According to another aspect of the present invention, there is provided a relay device that relays data transmitted between a transmission device and a reception device, and an encrypted packet header encrypted with a predetermined encryption method and encryption Including protocol conversion means for converting packet data of the first protocol input from the transmission device to packet data of the second protocol, the protocol conversion means comprising: An extension header including an extension bit, a conversion flag, the number of conversions, and a conversion pointer corresponding to the number of conversions is added to the header, and the data in the first packet is prepended to the data in the second packet. And the same encryption header, which is different only in length, is added, and a plurality of data in the first packet are collected to form data in the second packet.

  According to the present invention, it is possible to automatically select an optimal communication protocol in accordance with a transmission band, information on devices connected to a network, and a situation of a transmission medium.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Various copyright protection technologies that can be used when transmitting / receiving content data that needs to be protected have been developed. For example, in DTCP or the like, mutual authentication is performed between devices based on unique authenticator information possessed by each of a transmission device and a reception device, and a common key is generated. An encryption key for encrypting content is generated using the common key.

  Also, terrestrial digital broadcasting, BS digital broadcasting, and the like can be received by inserting a registered B-CAS card into a receiving tuner.

  In the embodiment of the present invention, the description of the above-described known device authentication is omitted. Moreover, in the following description, the same code | symbol is attached | subjected to the same components and component. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a diagram showing a network configuration between a home network in the home and the outside. The home network 201 is connected to the Internet 202 by a dedicated cable such as an optical fiber, ISDN, or ADSL. A plurality of types of communication devices including a home content server 204 are arranged in the home network 201.

  The home content server 204 can access an external content transmission device 203 via the Internet 202. The content transmission device 203 is a device managed by a content distributor such as a content provider. Various content data are transmitted from the content transmission device 203 to the home content server 204. For example, the home content server 204 stores the received content data in the home content server 204 itself based on the copyright information of the content, or relays the received content data to other communication in the home network 201. Decide whether to send to the device.

  Terrestrial digital broadcasting and BS digital broadcasting, which are examples of other content data, are transmitted by the terrestrial / satellite wave 205. The content data is received by the tuner device 206 via an antenna (not shown) and then stored in the home content server 204, for example.

  Note that the tuner device 206 may be incorporated in the home content server 204. Also, the content data received by the tuner device 206 is not stored in the home content server 204, but the home content server 204 functions as a relay device, and the content data is transmitted to other receiving devices in the home network 201. May be. The other receiving device is a viewing device for viewing AV content or the like typified by digital television, for example.

  Next, the device configuration in the home network 201 will be described in detail. The home content server 204 is a device that receives content provided from outside the home network 201. The home content server 204 includes a storage unit that can store the received content data. In addition, the home content server 204 has a function of transmitting received content data or stored content data to another receiving device.

  The home content server 204 can communicate with the content relay device 211, the content reception storage device 210, and the content reception device 207A. The content reception device 207A is wirelessly connected to the home content server 204. The content reception storage device 210 is configured to be connectable to the home content server 204 by either wireless or wired connection. The content receiving device 207A is a viewing device for viewing content, such as a stereo or a monitor device. The same applies to the content receiving devices 207B and 207C. On the other hand, the content reception storage device 210 is, for example, a device in which a digital hard disk as an example of a storage unit and a digital television as an example of a viewing device are integrated.

  The content relay apparatus 211 is connected to the home content server 204 by wire. The content relay device 211 is a device having a function of relaying received content data to another device for transmission.

  The content relay apparatus 211 includes an interface for wired connection and an interface for wireless connection. A content receiving device 207B, a content receiving device 208, and a content storage device 209 are connected to the content relay device 211.

  The content receiving device 207B is a device having an interface for wireless connection, and the content receiving device 208 and the content storage device 209 are devices having an interface for wired connection. The content storage device 209 is, for example, a digital hard disk. The content storage device 209 further includes an interface for wireless connection, and is wirelessly connected to the content reception device 207C through this interface.

  The receiving devices and storage devices that make up the home network 201 are distributed in a plurality of rooms in the home. By transmitting content data received from the outside to a desired device in the home network 201, a resident can view the content in a desired room in the home.

  The content storage device 209 or the content reception storage device 210 constituting the home network 201 receives content from other devices as well as a transmission device that transmits the content stored in the home network 201 in relation to the other devices. It can also be a receiving device. FIG. 2 is a diagram illustrating the transmitting device A, the relay device B, and the receiving device C, which are defined from the situation of transmitting and receiving content. Next, the configuration of the transmission device A and the relay device B defined in FIG. 2 will be described.

  FIG. 3 is a block diagram showing a configuration of the transmitting apparatus A shown in FIG. The transmission device A includes a device management unit 313 including a user interface unit 305, a network management unit 306, a network packet processing unit 309, and a wired network for connection such as Ethernet (registered trademark). It includes an interface unit 307, a wireless network interface unit 308, a hard disk device 302 that stores content data, and a content data input / output unit 301 that controls input / output of content data.

  When the transmission apparatus A is the content transmission apparatus 203 shown in FIG. 1, it further includes a content generation apparatus 303 that generates the content data itself. In this case, the content data input / output unit 301 notifies the network management unit 306 of the copyright information of the content data input from the content generation device 303. When the transmitting device A is the content reception / storing device 210 shown in FIG. 1, the transmitting device A further includes an output device 304 that outputs the content to a display or a speaker for viewing the content data so that the content can be viewed. .

  The device management unit 313 performs control related to the network of the system. When transmitting content data, the device management unit 313 sends a command to transmit content data from the user interface unit 305 to the network management unit 306. At this time, information for setting a protocol for transmitting content data from the user interface unit 305 may be input.

  The network management unit 306 receives a plurality of types of reference information serving as a reference for selecting a protocol. The first is protocol setting information indicating the type of protocol currently set. This information is input from the user interface unit 305. The second is network interface information indicating whether the wired interface and the wireless interface are operable. This information is input from the wired network interface unit 307 and the wireless network interface unit 308. The third is copyright information of content data to be transmitted. The fourth is device information of a receiving device that receives content data. This information is input from the network packet processing unit 309. The fifth item is usage information indicating how to use the receiving device.

  The network management unit 306 stores an information table related to input reference information (see FIGS. 4 to 7). The network management unit 306 determines a protocol for transmitting content data based on the input information and the stored information table. The protocol determination method will be described later. The network management unit 306 notifies the determined protocol to the network packet processing unit 309.

  The network packet processing unit 309 includes a protocol selection unit 314, an HTTP / RTP processing unit 310, a TCP / UDP processing unit 311, and a filtering unit 312.

  The network packet processing unit 309 receives content data to be transmitted. Further, control data other than content data is input from the device management unit 313 to the network packet processing unit 309. The protocol selection unit 314 selects a protocol for transmitting content data based on the protocol notified from the network management unit 306. The HTTP / RTP processing unit 310 has a function of converting content data into a packet format defined by the HTTP protocol or the RTP protocol. The TCP / UDP processing unit 311 has a function of further converting the data processed by the HTTP / RTP processing unit 310 into a packet format defined by the TCP protocol or the UDP protocol. The network packet processing unit 309 packetizes the content data by the HTTP / RTP processing unit 310 and the TCP / UDP processing unit 311 according to the protocol selected by the protocol selection unit 314. Note that control data for communication is also converted into packet data in the same manner as content data.

  The packetized data is sequentially transmitted from the wired network interface unit 307 or the wireless network interface unit 308 or both. In the present embodiment, only two protocols are illustrated as selectable protocols, but other network protocols may be further provided as options.

  When the content data and other control data are received via the wired network interface unit 307 or the wireless network interface unit 308, the filtering unit 312 analyzes the packets that constitute the received data. Then, the analysis result is notified to the device management unit 313. When the received data is content data, the data is transmitted to the content input / output unit 301. When the received data is control data, the data is transmitted to the device management unit 313.

  The device management unit 313 outputs instruction information indicating whether the received content data is stored in the hard disk device 307 or output to the content output device 304 to the network management unit 306. The network management unit 306 notifies the content data input / output unit 301 of the command.

  4 to 7 are diagrams illustrating information tables stored in the network management unit 306. FIG. The network management unit 306 selects a protocol using any one of the information tables shown in FIGS. 4 to 7 described below. Note that any information table may be preferentially used to select a protocol. Alternatively, only one of the information tables in FIGS. 4 to 7 may be stored in the network management unit 306, and the protocol may be selected based on only the information table. Alternatively, any two or more information tables in FIGS. 4 to 7 may be stored in the network management unit 306 and a protocol may be selected based on the information tables.

  FIG. 4 is a diagram showing an information table used for setting a protocol based on device information. The device information is information indicating whether a device to which content data is transmitted is a digital television, a digital hard disk, a device in which a digital television and a hard disk are integrated, or a relay device. “OK” in the display function and recording function column shown in FIG. 4 means that there is a function, and “NO” means that there is no function. Except for the relay device, each device has a recording function or a display function.

  The network management unit 306 selects a protocol based on the input device information and the information table shown in FIG. For example, when the device information is “digital television”, UDP / RTP suitable for viewing stream content in real time is selected. On the other hand, when the device information is “digital hard disk”, TCP / HTTP with no lost data at the time of recording is selected.

  In the case of a device in which a digital television and a digital hard disk are integrated, a protocol corresponding to the purpose of use of the device is selected. When only the display function is used, UDP / RTP is selected. On the other hand, when only a recording function such as a digital hard disk is used, TCP / HTTP is selected. When both are used on the same network interface, the TCP / HTTP protocol is selected.

  In the case of a relay device, the information table shown in FIGS. 5 to 7 is referred to, and a protocol depending on the transmission medium, content type, content copyright information, and usage information is selected.

  FIG. 5 is a diagram showing an information table used for setting a protocol based on network interface information. According to this information table, TCP / HTTP is selected when the content type is stationary, whether wired or wireless. On the other hand, when the content type is a stream system, TCP / HTTP or UDP / RTP is selected according to the line state.

  When the network interface is wired and the content type is a stream type, the protocol is selected according to the usable bandwidth ratio of the line. That is, when the usable bandwidth ratio is 0.8 or more, TCP / HTTP is selected, and when it is less than 0.8, UDP / RTP is selected. The usable bandwidth ratio is a communication ratio in which the ratio of the transmission rate at which content can be transmitted at the interface is ratioized. For example, the communication ratio when the transmission rate of a line having a maximum transmission band of 100 Mbps is changed to 80 Mbps depending on the communication state is 0.8 by calculating with the following formula.

Communication ratio (usable bandwidth ratio) = Transmission rate available for communication (bps) / Maximum transmission rate available for network interface (bps)
When the network interface is wireless and the content type is a stream type, the protocol is selected as follows depending on whether or not data loss occurs.

  First, when data loss occurs, UDP / RTP is selected. On the other hand, when data loss does not occur, a protocol is selected according to the available bandwidth ratio of the wireless line. When the usable bandwidth ratio is 0.8 or more, TCP / HTTP is selected, and when it is less than 0.8, UDP / RTP is selected.

  FIG. 6 is a diagram showing an information table used for setting a protocol based on copyright information. In the present embodiment, the copyright information is the number of content copy restrictions.

  In the case of Copy Never, UDP / RTP is selected as the stream system. In the case of Copy One Generation, TCP / HTTP is selected because it may be stored in the receiving device. In the case of Move and NO more copies, the UDP / RTP protocol is selected. In the case of Copy Free, the TCP / HTTP protocol is selected.

  FIG. 7 is a diagram illustrating an information table used for setting a protocol based on usage information. When the receiving apparatus is a digital television, the user can only view it, so the default protocol is set as UDP / RTP as Play Only. If the receiving device is a hard disk device, the user can only use Copy or Move, so the default protocol is set by TCP / HTTP. Alternatively, when the receiving device is an integrated type such as a hard disk device having a recorder function or a digital television having a copy function, the default protocol is set by TCP / HTTP as Play and Copy. These default settings and weighting based on these pieces of information are merely examples, and the present invention is not limited thereto.

  8 and 9 are flowcharts showing the procedure of the process for determining the protocol. Here, as an example, a processing procedure when the information table shown in FIG. 5 is used will be described. Control based on this flowchart is executed by the transmitting apparatus A shown in FIG. Further, this control is similarly executed by a relay apparatus B shown in FIG.

  First, the transmitter is turned on and activated (S20). When the receiving apparatus enters the network and accesses the transmitting apparatus (YES in S21), information on the network interface of the transmitting apparatus itself is input (S22). This is information indicating whether the transmission device is connected to the reception device wirelessly or by wire.

  If the wireless connection is established, the type of content selected from the receiving device is confirmed (S24). Similarly, in the case of wired communication, the type of content selected from the receiving device is confirmed (S25). Then, it is determined whether the content is a stream system or a stationary system (S26, S27). Specifically, it is determined whether it is a still system or a stream system based on the extension of the selected content file. For example, if it is JPEG, GIF, PNG, etc., it will be determined as a static system, and if it is MPEG-TS, DV, etc., it will be determined as a stream system.

  If the network interface is wireless and the requested content is a static system, the protocol is determined to be TCP / HTTP (S37). If the network interface is wired and the requested content is a static system, the protocol is determined to be TCP / HTTP (S28).

  When the network interface is wired and the requested content is a stream system, the usable bandwidth ratio is calculated (S37). If the usable bandwidth ratio is less than 0.8 (YES in S39), the protocol is determined to be UDP / RTP (S40). If the usable bandwidth ratio is 0.8 or more (NO in S39), the protocol is determined to be TCP / HTTP (S38). Then, the available bandwidth ratio is calculated again every preset time T (S41), and it is repeatedly determined whether or not to change the protocol.

  If the network interface is wireless and the requested content is a stream system, the available bandwidth ratio is calculated (S31). Next, it is determined whether or not a lost transmission has occurred (S32). If lost has occurred, the protocol is determined to be UDP / RTP regardless of the available bandwidth ratio calculated in S31 (S34). If no loss occurs, the protocol is determined according to the available bandwidth ratio. Specifically, if the usable bandwidth ratio is less than 0.8 (YES in S33), the protocol is determined to be UDP / RTP (S34). If the usable bandwidth ratio is 0.8 or more (NO in S33), the protocol is determined to be TCP / HTTP (S35). Then, the available bandwidth ratio is calculated again every preset time T (S36), and it is repeatedly determined whether or not to change the protocol.

  FIG. 10 is a diagram showing a UDP / RTP packet format used in the present embodiment. A packet 801 based on UDP / RTP includes an IP header, a UDP header, an RTP header, and data. In the case of Ethernet (registered trademark), which is an example of a wired medium, the maximum size that can be transmitted at one time is defined as 1500 bytes after adding an Ethernet (registered trademark) header. Since the header size of Ethernet (registered trademark) is 18 bytes, the IP header size is 20 bytes minimum, the UDP header size is 8 bytes, and the RTP header size is 12 bytes minimum, the data size is a maximum of 1442 bytes.

  For example, since one packet size of MPEG2-TS is 188 bytes, when MPEG2-TS is transmitted as content data, it is possible to insert seven packets of MPEG2-TS. Since the UDP / RTP protocol does not have retransmission processing, the efficiency is improved by adjusting to the maximum transmission size of the delimited network interface.

  FIG. 11 shows a TCP / HTTP packet format used in the present embodiment. The TCP header size is a minimum of 20 bytes, and the HTTP header size is variable. The HTTP header is in a text format called meta information.

  TCP / HTTP defines a process for retransmitting data that could not be received. For this reason, data can be reliably transmitted to the other party. However, this causes a delay before the data arrives at the receiving device. In the case of Ethernet (registered trademark), the size of the packet 901 including the IP header, TCP header, HTTP header, and data is 1500 bytes including the header of Ethernet (registered trademark). In addition, the size of the packet 901 in the case of wireless communication based on IEEE 802.11b is 2048 bytes. Whether wired or wireless, transfer efficiency can be increased by setting the packet size to the maximum transmission size of the network interface.

  FIG. 12 is a block diagram showing a configuration of relay apparatus B shown in FIG. The configuration of the relay device B is obtained by adding a protocol conversion processing unit 700 to the network packet processing unit 309 of the transmission device A shown in FIG.

  The relay device B is interposed between a transmission device that transmits content data and a reception device that receives content data, and relays the content data. For example, the relay device B receives the content data transmitted from the transmission device by the wired network interface 307 and inputs the content data to the network packet processing unit 309, and then transmits the content data from the wireless network interface 308 to the reception device.

  The relay apparatus B stores the information tables illustrated in FIGS. 4 to 7 as in the case of the transmission apparatus A illustrated in FIG. 3, and selects an optimum protocol for transmitting content data to the reception apparatus. It has a function. Further, the relay device B executes the control shown in FIGS. The relay device includes a protocol conversion function for converting the protocol of data received from the transmission device into a protocol for communication with the reception device when the selected protocol is different from the protocol defined with the transmission device. This protocol conversion function is realized by the protocol conversion processing unit 700.

  The protocol conversion processing unit 700 converts the data protocol between TCP / HTTP and UDP / RTP. As a result, it is possible to transmit content data from the transmission device to the reception device using an appropriate transmission protocol according to the situation between the transmission device and the relay device B and the situation between the relay device B and the reception device.

  For example, the content data is a stream system, and the communication medium between the transmission apparatus and the relay apparatus B is configured by a wired medium having a high usable bandwidth ratio (≧ 0.8), while the relay apparatus B and the reception apparatus Assume that the communication medium between the two is composed of a wireless medium with a lot of lost. In this case, according to the information table shown in FIG. 5, the transmission device selects TCP / HTTP as the transmission protocol with the relay device. On the other hand, according to the information table shown in FIG. 5, the relay device B selects UDP / RTP as a transmission protocol between the relay device B and the receiving device. The protocol conversion processing unit 700 of the relay apparatus B converts the protocol of content data transmitted from the transmission apparatus from TCP / HTTP to UDP / RTP. As a result, the content data can be received from the transmitting device using an appropriate protocol, and the content data can be transmitted to the receiving device using an appropriate protocol.

  Alternatively, when the receiving device is the content receiving device 207B or 208 shown in FIG. 1, the content data is reliably received by TCP / HTTP with little communication loss between the transmitting device and the relay device B, and relayed. It is also possible to transmit content data between the device B and the receiving device using UDP / RTP with excellent real-time characteristics.

  FIG. 13 is a block diagram illustrating a configuration of the protocol conversion processing unit 700. FIG. 14 is a flowchart illustrating a processing procedure executed by the protocol conversion processing unit 700. Further, FIG. 15 is a diagram showing how data is stored in the buffer memory 1100. The flowchart shown in FIG. 4 shows processing for converting HTTP protocol data to the RTP protocol, or processing for converting RTP protocol data to the HTTP protocol.

  As illustrated in FIG. 13, the protocol conversion processing unit 700 includes a buffer memory 1100, a time processing unit 1101, and an output control unit 1102. The buffer memory 1100 receives content data transmitted from the transmission device via the HTTP / RTP processing unit 310. Thus, the content data transmitted to the receiving device is temporarily stored in the buffer memory 1100. The accumulated content data is transferred to the output control unit 1102 every time a predetermined output condition is satisfied. The protocol of data input to the HTTP / RTP processing unit 310 and the protocol of data to be output are set by the protocol determination process described above.

  Hereinafter, the operation of the protocol conversion processing unit 700 will be described by taking as an example a case where content data of the HTTP protocol received from the transmission device is converted into the RTP protocol and transmitted to the reception device.

  The time management processing unit 1101 sets the output time α_Time. α_Time is a timer used to output a part of the content data stored in the buffer memory 1100 to the output control unit 1102. β_Length is an output data size per packet, and is, for example, one packet length defined by a protocol for outputting data. β_Length is one piece of network interface information output by the network management unit 306. The output control unit 1101 delivers the data output from the buffer memory 1100 to the HTTP / RTP processing unit using α_Time and β_Length as thresholds.

  When data is output using the RTP protocol, time is given priority. However, when data is output using the HTTP protocol, time is not given priority over the RTP protocol. First, when data is input from the HTTP / RTP processing unit 310 to the buffer memory 1100, YES is determined in S1, and α_Time and β_Length are set (S2). Next, together with the input data, timer data created by the time management processing unit 1101 shown in FIG. 13 and data indicating the accumulated size of the accumulated data are accumulated in the buffer memory 1100 (S4). . In FIG. 15, the input data 0 to N are accumulated, and the timer T (0). . . A state is shown in which data is accumulated up to T (N) and cumulative sizes 0 to N are accumulated.

  Next, the timer value of the currently accumulated data is compared with α_Time to determine whether or not the data waiting time exceeds the set value (α_Time) (S5). When the data waiting time exceeds the set value (α_Time), it is determined that the data output condition is satisfied, and the following processes of S10 to S12 are executed.

  First, the accumulated data size value and timer value are updated (S10, S11). Next, the output control unit 1102 extracts the data size to be output from the buffer memory 1100 and outputs it to the HTTP / RTP processing unit 301.

  When it is determined in S5 that the data standby time does not exceed the set value (α_Time), the data accumulated size is compared with β_Length (S6). If the accumulated data size> β_Length, it is determined that the data output condition is satisfied, and the processes of S10 to S12 are executed.

If the accumulated data size is not greater than β_Length, the next data is input to the buffer memory 1100 (S7). Next, a timer when data is input to the buffer memory 1100 is calculated (S8). Next, the accumulated data size is updated according to the input data size (S9). Thereafter, the process proceeds to S4. Specifically method of updating the accumulated data size, the data size _{α_ N (N: 0 ... N} ), and the time is as follows.

Cumulative size = α_ ₀ + α_ ₁ + α_ ₂
If β_Length <cumulative size,
offset_size = β_Length-cumulative size Update cumulative size from
Update cumulative size = offset_size + α_ ₃ … + α_ _N
When β_Length is exceeded, the data size accumulated so far is subtracted, and the offset value (offset_size) is added to the next input data size. Next, a specific method of updating the timer value, the timer value _{Γ_ N (N: 0 ... J} ... N), if α_Time <Γ_ _j, is as follows.

Update timer value _{= Γ_ j + 1 (N:} J + 1 ...... N) -Γ_ j
When α_Time is exceeded, the current timer is used as an offset, and the offset value is subtracted from the subsequent data. Further, in the example, it is assumed that the data transmission protocol is not sequentially converted and the protocol continues for a certain time. When updating sequentially, the process is performed from S1 every time the protocol changes.

  Further, the timer value and the accumulated size value may be stored in a place other than the buffer memory 1100. Table data in which the address in the buffer memory 1100 and the address of the memory storing the timer value and the accumulated size value are mapped on a one-to-one basis is prepared, and stored in the buffer memory 1100 by referring to the table It is conceivable to make it possible to specify the timer value and cumulative size value of the input data.

  Furthermore, the β_Length to be set is preferably the data size per packet that can be transmitted through the network interface from the viewpoint of transmission efficiency, but all data can be transmitted when the current timer value exceeds α_Time depending on the value of α_Time. Therefore, the timer value is preferably set based on the value of β_Length and the transmission state of the protocol.

  FIG. 16 is a block diagram showing another configuration of transmitting apparatus A shown in FIG. A transmission apparatus A ′ illustrated in FIG. 16 is provided with a device authentication unit 1000 and a content encryption / decryption processing unit 1001 in addition to the configuration of the transmission apparatus A illustrated in FIG. The content encryption / decryption processing unit 1001 performs encryption / decryption processing on content data requiring copyright protection technology. The device authentication unit 1000 performs inter-device authentication with a receiving device that receives content data, and generates an encryption key for the content data.

  Encryption by the device uses DTCP technology. An outline of mutual authentication between the transmission device and the reception device will be described as follows.

  In the authentication process between devices, the device authentication unit 1000 performs authentication with the receiving device. Information necessary for this authentication is packetized by the TCP / UDP processing unit 311 using the TCP protocol.

  When the transmitting device and the receiving device are authenticated as valid DTCP devices by the authentication between the devices, a common key is generated between the transmitting device and the receiving device. Next, a content encryption key is generated based on the generated common key, content copyright information, and content switching timing information. Next, the content data is encrypted with the encryption key, and the encrypted data is transmitted from the transmission device to the reception device. The receiving device generates a decryption key from the common key based on the copyright information of the content added to the transmission packet and the content switching timing information, and decrypts the encrypted content data.

  FIG. 17 is a block diagram showing another configuration of relay apparatus B shown in FIG. The relay device B ′ shown in FIG. 17 has a copyright protection content packet reconstruction unit 1800 added to the configuration of the relay device B shown in FIG. In response to a protocol conversion request from the network management unit 306, the copyright protection content packet reconstruction unit 1800 receives the encrypted data portion of the packet data corresponding to the input protocol from the network packet management unit 309, and converts the encrypted data into The data is reconfigured into encrypted data corresponding to the packet of the output protocol and output to the network packet management unit 309. Therefore, according to the relay device B ′ shown in FIG. 17, it is possible to relay content data that requires copyright protection technology and convert the protocol to an optimum one.

  Next, a method for converting the protocol of encrypted data will be described with reference to FIGS. FIG. 18 is a diagram for explaining processing for converting encrypted data transmitted by the HTTP protocol into encrypted data transmitted by the RTP protocol.

  In general, the data transmitted by the HTTP protocol has a data length larger than the data transmitted by the RTP protocol. Here, it is assumed that the HTTP payload portion 1900 indicates the entire content with one PCP.

  The encrypted content 1903 after the PCP header 1902 propagates the influence of encryption in 128-bit units depending on the AES-128-bit CBC mode in the transmission apparatus. Therefore, the encrypted content 1903 is divided into RTP protocol data lengths. That is, the division unit is set to the packet length when one packet is transmitted through the network interface using the UDP / RTP protocol.

  Assume that the number of divided encrypted contents is N. Reference numeral 1916 denotes the first RTP packet. 1914 indicates the second RTP packet. Reference numeral 1915 denotes the last RTP packet. The payload portion 1907 of the RTP packet is composed of a PCP header 1905 and fragmented encrypted content 1906. The PCP header 1905 includes content length information indicating the data length of the encrypted content 1906. The data in the PCP header 1905 is the same as the data in the HTTP PCP header 1902 before the division except for the content length data. Thus, for example, the PCP header 1905 of the second RTP packet 1914 is the same as the first RTP packet.

  In the first RTP packet 1916, 1908 indicates the last 128-bit data of the encrypted content 1906. The first 128-bit data of the encrypted content 1917 of the second RTP packet 1914 is the same as the last 128-bit data 1908 of the first encrypted content 1906. Similarly, the first 128-bit data of the encrypted content of the Nth RTP packet 1915 is the same as the last 128-bit data 1913 of the encrypted content of the N−1th RTP packet. In this way, by providing redundancy to the first 128-bit data of each encrypted content, the propagation of encryption between RTP packets can be maintained even when RTP packets are lost. In the last RTP packet 1915, since the encrypted content to be subdivided is less than the RTP packet length, padding 1910 is inserted.

  In the AES-128 bit CBC mode, which is DTCP encryption, the initialization vector value is XORed with respect to the first encrypted data. For this reason, it is necessary to identify the first encrypted data at the time of decryption. Further, it is necessary to decrypt the encrypted data other than the first encrypted data by removing the first 128 bits of the encrypted content. For this reason, it is necessary to identify the first packet and the subsequent packets. Therefore, an extension bit 1911 (= 1) is set in the RTP header 1904 separately from the RTP header portion 1904a, and the extension header 1912 is added. In the extension header 1912, a head flag 1920 indicating the head, a padding flag 1921 indicating whether padding is being performed, and information 1922 indicating the padding length are entered.

  A receiving apparatus that receives an RTP packet can perform decoding by a decoding method defined in DTCP by referring to such an extended portion of the RTP header. When the encrypted data converted into the HTTP protocol packet data is reconfigured into the RTP protocol packet data, as described above, one packet of the HTTP protocol packet data is stored in the temporary memory of the relay device. The RTP packet may be reconstructed after receiving the packet. However, with this method, the size of the memory is required for the packet data size of the HTTP protocol. Therefore, instead of completely receiving one packet data of the HTTP protocol, it may be output as an RTP packet in the same manner as described above if the packet data size of the RTP protocol can be received by the relay apparatus.

  FIG. 19 is a diagram for explaining processing for converting encrypted data transmitted using the RTP protocol into encrypted data transmitted using the HTTP protocol. When an encrypted packet is transmitted by the RTP protocol using the DTCP technique, the initialization vector value may be different for each RTP packet. In addition, propagation of the influence of AES-128-bit CBC mode encryption, which is DTCP encryption technology, is in units of RTP packets and does not propagate between packets.

  In FIG. 19, RTP packets 2001, 2002, 2008, 2010, 2003, and 2004 indicate that one whole content data is subdivided into payloads of RTP packets and subdivided into N packet data.

  In addition to the RTP header 2005, the RTP 2005 includes bit data 2021 indicating an order (sequence number). Bit data 2021 can be used to identify whether a packet has been lost when receiving RTP packet data. The bit data 2021 is sequentially incremented by +1 for each packet. NC1504 shown in FIG. 22 is information indicating switching of encryption. For this reason, NC of PCP header 1 (2006), PCP header 2 (2015), and PCP header J (2009) are the same value. The NCs of the PCP header J + (2011), the PCP header N-1 (2019), and the PCP header N (2020) are the same value.

  Therefore, in the case of the same NC, it can be considered that it is encrypted with the same encryption key. For this reason, if the encrypted content of the RTP packet with the same NC is transmitted with one HTTP payload 2016, one NC is sufficient in the PCP header of the HTTP packet, and no extra data is added. It's okay. Thereby, substantial transmission efficiency can be improved.

  However, in the CBC mode, XOR processing using the initialization vector value is performed for the first 128 bits for each RTP packet 2001, 2002, 2008, 2010, 2003, 2004. For this reason, when decrypting the HTTP payload 2016, it is necessary to be able to specify the ciphertext switching position within the payload 2016. Therefore, bit data 2017 indicating extension and an extension header 2014 are set in the HTTP header 2012. Further, in the extension header 2014, a conversion flag 2030 indicating whether or not there is a conversion point in the encrypted content data in the payload (whether or not two or more ciphertexts are stored), and the number of conversions Data 2031 indicating (the number of stored ciphertexts) and a conversion pointer 2032 indicating a conversion position (start position of each ciphertext) corresponding to the number are included. In the figure, arrows extending from the conversion pointers 1, 2,... N to the encrypted content 2013 are conversion points indicated by the conversion pointers.

  According to this method, since the conversion pointer can be identified by referring to the extension header portion when received by the HTTP protocol, the data can be decoded on the receiving device side. When the influence of encryption propagates in the basic unit of encryption (128 bit unit if AES-128) like CBC, the above-described method can be applied.

  FIG. 20 is a diagram illustrating a flow of processing when content data requiring copyright protection is transmitted from the transmission device to the reception device via the relay device. Here, a case where the transmitting device is the hard disk recorder 2100 and the receiving device is the digital television 2102 will be described.

  The hard disk recorder 2100 stores content data. The hard disk recorder 2100 and the relay apparatus 2101 are connected by an Ethernet (registered trademark) 2103. It is assumed that the relay apparatus 2101 and the digital television are wirelessly connected by IEEE802.11b (2104).

  First, when the hard disk recorder 2100 and the digital television 2102 are connected via the relay device 2101, the digital television 2102 transmits device information to the hard disk recorder 2100 (SP3000). The transmission protocol at this time is the TCP / HTTP protocol (2105). In response to the transmission data of SP3000, ACK as response data is returned from the hard disk recorder 2100 (SP3001).

  Similarly, the hard disk recorder 2100 transmits device information to the digital television 2102 (SP3002). The response data ACK is returned from the digital television 2102 (SP3003).

  From the reply data (SP3001, SP3003), the hard disk recorder 2100 and the digital television 2102 understand each other's devices. Further, the relay apparatus 2101 understands both partner apparatuses from the exchanged data.

  Further, the hard disk recorder 2100, the digital television 2102, and the relay device 2101 are an Ethernet (registered trademark) 2103 that is a transmission medium between the hard disk recorder 2100 and the relay device 2101, and between the relay device 2101 and the digital television 2102. Understand IEEE 802.11b as a transmission medium (3013).

  Next, the hard disk recorder 2100 sends the stored content information to the digital television 2102. The digital television 2102 displays the received content information on the screen (SP3004). Further, the digital television 2102 returns a response to the received content information as an ACK to the hard disk recorder 2100 (SP3005).

  Next, the user selects content on the digital television 2102 using an operation device such as a remote controller (SP3006). As a result, selection information indicating that the user has selected content is transmitted from the digital television 2102 to the hard disk recorder 2100. The hard disk recorder 2100 determines whether copyright protection technology is necessary for the content selected by the user from the selection information (SP3007).

  ACK data for the selection information is returned to the digital television 2102. If the content selected by the user is content that requires copyright protection technology, DTCP device authentication 3012 is performed between the hard disk recorder 2100 and the digital television 2102 (SP3009, SP3010). The relay device 2101 relays data transmitted and received between the hard disk recorder 2100 and the digital television 2102.

  Next, a transmission protocol is determined by protocol determination processing. Here, the protocol determination process based on the transmission medium will be described. Between the hard disk recorder 2100 and the relay apparatus 2101 is a wired medium. Therefore, the hard disk recorder 2100 determines the transmission protocol as the TCP / HTTP protocol (SP3011). Between the relay apparatus 2101 and the digital television 2102 is a wireless medium. Therefore, the relay apparatus 2101 determines the transmission protocol as the UDP / RTP protocol (SP3012).

  Next, the hard disk recorder 2100 encrypts the selected content and transmits it to the relay apparatus 2101 using the TCP / HTTP protocol. The relay apparatus 2101 converts the protocol of the received data from HTTP to RTP (SP3017), and transmits the data to the digital television 2102 using the UDP protocol.

  One arrow heading from SP3013 toward the relay device is changed to three arrows through the conversion of SP3017. This indicates that one HTTP packet is converted into three RTP packets.

  The relay apparatus 2101 returns a response to the received HTTP packet as an ACK to the hard disk recorder 2100 (SP3016). In the case of SP3016, ACK is returned after RTP transmission is completed, but ACK may be returned when the HTTP packet of SP3013 is received.

  The digital television 2102 sequentially receives the received encrypted content of the RTP protocol (SP3014) and displays the content on the screen (SP3015). Until the content transmission is completed, the processing steps from SP3013 to SP3015 are repeated. Note that protocol determination information such as device information and content information is added to the extension header of each protocol header, for example. As a result, it is possible for each device to understand information on each device and content information.

  According to the present invention, it is possible to automatically select an optimal communication protocol in accordance with the transmission band, information on devices connected to the network, and the state of the transmission medium, and the content data itself is encrypted. Protocol conversion is possible without breaking the encryption mechanism even if it is applied.

  Furthermore, according to the present invention, when content that requires copyright protection technology is transmitted over a network in which a relay device exists, the encrypted content is not decrypted between the transmission device and the reception device, and the copyright is protected. A transmission device, a reception device, and a relay device that have a function to select a protocol according to information on the devices connected to the network and the status of the transmission medium while effectively utilizing the transmission band on the network while ensuring protection technology. Can be provided.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the network structure of the home network in a home, and the exterior. It is a figure which shows a transmitter, a relay apparatus, and a receiver. It is a block diagram which shows the structure of the transmitter shown by FIG. It is a figure which shows the information table which the network management part has memorize | stored. It is a figure which shows the information table which the network management part has memorize | stored. It is a figure which shows the information table which the network management part has memorize | stored. It is a figure which shows the information table which the network management part has memorize | stored. It is a flowchart which shows the procedure of the process which determines a protocol. It is a flowchart which shows the procedure of the process which determines a protocol. It is a figure which shows the packet format of UDP / RTP used by this Embodiment. This is a TCP / HTTP packet format used in the present embodiment. It is a block diagram which shows the structure of the relay apparatus shown by FIG. It is a block diagram which shows the structure of a protocol conversion process part. It is a flowchart which shows the process sequence which a protocol conversion process part performs. It is a figure which shows a mode that data are accumulate | stored in a buffer memory. It is a block diagram which shows the other structure of the transmitter shown by FIG. It is a block diagram which shows the other structure of the relay apparatus shown by FIG. It is a figure for demonstrating the process which converts the encryption data transmitted with the protocol of HTTP into the encryption data transmitted with the protocol of RTP. It is a figure for demonstrating the process which converts the encryption data transmitted with the protocol of RTP into the encryption data transmitted with the protocol of HTTP. It is a figure which shows the flow of a process when transmitting the content data which needs copyright protection from a transmission apparatus to a receiving device via a relay apparatus. It is a figure which shows a network model. It is a figure which shows the format of the packet in the case of transmitting data by UDP / RTP and TCP / HTTP. It is a figure which shows the mechanism of the encryption by CBC mode.

Explanation of symbols

  201 home network, 203 content transmission device, 204 home content server, 207A, 207B, 207C content reception device, 208 content reception device, 209 content storage device, 210 content reception storage device

Claims (13)

A transmission device including a plurality of protocols for transmitting content data to a reception device,
A transmission device comprising: protocol selection means for selecting a transmission protocol based on device information of a reception device when transmitting content data.   The transmission apparatus according to claim 1, wherein the apparatus information is information indicating presence / absence of a display function and a recording function. A transmission device including a plurality of protocols for transmitting content data to a reception device,
A transmission apparatus comprising: a protocol selection unit that selects a transmission protocol based on content data copy restriction information when transmitting content data. A transmission device including a plurality of protocols for transmitting content data to a reception device,
A transmission apparatus, comprising: a protocol selection unit that selects a transmission protocol based on information indicating a usage method of a reception apparatus when transmitting content data.   The transmission device according to claim 1, wherein the protocol selection unit selects a transmission protocol from an RTP protocol and an HTTP protocol. A relay device that relays data transmitted between a transmission device and a reception device,
Protocol selection means for selecting a transmission protocol when transmitting content data;
Protocol conversion means for converting a transmission protocol of content data input from the transmission device into a transmission protocol selected by the protocol selection means;
A relay apparatus comprising: output means for outputting content data converted by the protocol conversion means to the receiving apparatus. Storage means for storing data input from the transmission device;
Data length determination means for determining whether or not the data stored in the storage means has reached the data length of the packet defined by the transmission protocol selected by the protocol selection means;
The output packet generation means for generating an output packet from the data stored in the storage means when the data length determination means determines that the data length has been reached. Relay device. Storage means for storing data input from the transmission device and input timing of the data;
Time determination means for determining whether or not a predetermined time has elapsed since data was input from the transmission device;
The output packet generation means for generating an output packet from the data stored in the storage means when the time determination means determines that the predetermined time has passed. Relay device. A relay device that relays data transmitted between a transmission device and a reception device,
Protocol conversion for converting packet data of the first protocol input from the transmission device into packet data of the second protocol, which includes an encrypted packet header and encrypted data encrypted by a predetermined encryption method With means,
The protocol conversion means includes:
Adding an extension header including an extension bit and a head flag, a padding flag, and a padding length to the header of the second packet data;
At the head of the data in the second packet, add the same encryption header that differs only in length from the data in the first packet,
A relay device, wherein the data in the first packet is subdivided and divided into data in the second packet and mounted.   The relay apparatus according to claim 9, wherein the first protocol is HTTP, and the second protocol is RTP.   The relay apparatus according to claim 9 or 10, wherein the encryption method is a CBC method. A relay device that relays data transmitted between a transmission device and a reception device,
Protocol conversion for converting packet data of the first protocol input from the transmission apparatus into packet data of the second protocol, which includes an encrypted packet header and encrypted data encrypted by a predetermined encryption method With means,
The protocol conversion means includes:
An extension header including an extension bit, a conversion flag, a conversion number, and a conversion pointer corresponding to the conversion number is added to the header of the second packet data;
At the head of the data in the second packet, the same encryption header that is different in length from the data in the first packet is added, and a plurality of data in the first packet are collected, and the second packet is collected. A relay device characterized in that the data is in the data of a packet.   The relay apparatus according to claim 12, wherein the first protocol is RTP, and the second protocol is HTTP.

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