JP2006352185A - Content transmission apparatus and content receiving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of the stop of a reproduced video image at the occurrence of an error in a transmission path when transmitting contents by using a wired or wireless LAN, and to provide a technology capable of attaining the immediate start of reproduction even if the reproduced video image is stopped. <P>SOLUTION: A content transmission apparatus transmits only encryption information to a content receiving apparatus through a path other than a path for content transmission when the content transmission apparatus transmits contents to the content receiving apparatus. Further, in the case of transmitting encryption data to the content receiving apparatus in combination with the method as above, the transmission apparatus optimizes the size of a transmitted IP packet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transmitting device and a receiving device suitable for protecting the copyright of transmitted content when transmitting and receiving content such as video and audio via a network.

  With the development of processing capacity such as the computing speed and storage capacity of personal computers (hereinafter referred to as PCs), the capacity of hard disk drives (hereinafter referred to as HDDs) built into PCs is also increasing. Under these circumstances, it is now possible to record TV broadcast programs using a HDD and view them on a PC display even on a PC with a rank that is used in general households. I came. On the other hand, due to the low price of large-capacity HDDs, HDD recording devices that have built-in HDDs and digitally record video and audio information are also appearing as home recording devices, and discs are used as recording media. Ease of use due to the use is attracting attention. In parallel with the increase in the speed and capacity of PCs, the Internet is also rapidly spreading, and high-speed network systems using optical fibers have been developed. With the development of the above-mentioned PC and network system, it is possible to digitize not only digital data used on the PC but also video signals and audio signals, and transmit high-quality video signals and audio signals in real time.

In this situation, the recording device is equipped with a wired or wireless LAN (Local Area Network) interface and sent to other PCs or receiving devices via the network to view the recorded video and audio information anywhere in the house. An example of an apparatus that can be used is described in Non-Patent Document 1.
However, when transmitting data that requires real-time in a wired or wireless LAN, data stored in an IP (Internet Protocol) packet is lost along the route due to congestion of the network, resulting in a problem of impairing real-time. Therefore, for example, in Patent Document 1, in the network system, even if an error occurs in the data in the required data transmission process, retransmission of the data in which the error has occurred is performed after completion of transmission of all the requested data. Thus, it is disclosed that continuous communication is possible without impairing real-time performance by avoiding disruption of the network due to data retransmission. For example, Patent Document 2 uses an ARQ (Automatic Repeat reQuest) function to efficiently use a retransmission request, and a data receiving terminal considers a reproduction processing time and a propagation delay time (RTT: Round Trip Time) to perform reproduction processing. There is disclosed a data communication system that enables high-quality data reproduction by not performing retransmission request processing when it is not in time.

JP 10-313350 A (page 12 [0111]) Japanese Patent Laying-Open No. 2003-169040 (page 27, FIG. 11) Toshiba Review, Vol. 57 No9. (Page 6-7)

  In Patent Document 1, when an error occurs in data during the required data transmission process, after the transmission of all requested data is completed, the data with the error is retransmitted. Patent Document 2 has a configuration in which a retransmission request is efficiently used and the retransmission request process is not executed when the retransmission process is not in time. In Patent Document 1, for example, when data is encrypted and transmitted by a DTCP-IP (Digital Transmission Content Protection over Internet Protocol) method that considers copyright protection of contents, for example, encryption information is incorporated into data in which an error has occurred. In this case, the encrypted data cannot be decrypted until the data incorporating the encrypted information arrives by retransmission. Further, if the retransmission request process is not executed when the retransmission process shown in Patent Document 2 is not in time, if the retransmission request process is not performed on the data in which the encryption information is incorporated, the encryption information is received on the receiving device side. Cannot be understood and cannot be decrypted.

  An object of the present invention is to provide a system in which a receiving apparatus can perform a decryption process even when an error occurs in data in which the encryption information is incorporated in an IP network.

  In order to solve the above problem, in the present invention, a content transmission apparatus that transmits and receives content via a wired or wireless LAN is connected to network communication processing means that transmits and receives data via a network. Content generating means for supplying the content to be transmitted to the content receiving device to the network communication means, receiving an authentication request from the content receiving device, determining authentication for the authentication request, and issuing an authentication request to the content receiving device. An authenticating means for issuing, a key information is generated based on information generated based on information obtained by executing an authentication process by the authenticating means, and a content encrypting means for transmitting to the content receiving device using the key information; Sending an authentication request to the device or receiving content Timer means for measuring the time until arrival of reception confirmation from the content receiving apparatus in response to transmission of a response to the authentication request from the server, and transmitting the encryption information and encrypted data used for encryption to the content receiving apparatus In addition, a route different from the route used in the process is secured with the content receiving apparatus, and the encrypted information is transmitted to the content receiving apparatus using the secured path.

  As a result, even if an error occurs in the encrypted information on the normal path and it does not arrive at the content receiving apparatus, the encrypted information can be obtained through the path secured for the transmission of the encrypted information, and can be decrypted and reproduced. That is, when content data is transmitted via a wired or wireless LAN, it is possible to solve the problem that the video reproduction process is stopped due to a content data error, and it is possible to minimize the time that cannot be reproduced due to the occurrence of an error.

  According to the present invention, it is possible to realize a system in which a receiving apparatus can perform a decryption process even when an error occurs in data in which encryption information is incorporated in an IP network.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration of a content transmission device 100 and a content reception device 200 according to an embodiment of the present invention. The content transmission device 100 and the content reception device 200 are connected to each other via a LAN. In the content transmission apparatus 100, 101 is a content transmission circuit that transmits content to the content transmission apparatus 200, 102 is an encryption circuit that encrypts content output from the content transmission circuit 101, and 103 is an output and authentication circuit 104 of the encryption circuit 102. Is a network communication processing circuit that exchanges I / O with other devices via a LAN, and an authentication circuit 105 that exchanges information with other devices connected on the LAN and performs mutual authentication between the devices. Nonvolatile memory for storing information necessary for processing in the authentication circuit 104, 106 a key generation circuit for generating key information necessary for content encryption in the encryption circuit 102 based on the information in the authentication circuit 104, 107 an authentication circuit After transmitting information such as an authentication request generated by 104 to another apparatus, confirmation of reception of the information is performed. A timer circuit that measures the time to reach, and an identification code of “Copy free”, “Copy one generation”, “No more copies”, “Copy never” indicating how to handle the content transmitted from the content transmission circuit 101 To the content receiving apparatus 200.

  In the content receiving apparatus 200, 201 is a content receiving circuit that receives content sent via a LAN, 202 is a composite that receives content encrypted by the encryption circuit 102 of the content transmitting circuit 100 from the network communication processing circuit 203. A composite circuit 203 that outputs the content to the content reception circuit 201 and 203 is a network communication processing circuit that exchanges input to and output from the composite circuit 202 and input / output of the authentication circuit 204 with other devices via a network. An authentication circuit that performs mutual authentication between devices by exchanging information with other devices, 205 is a non-volatile memory that stores information necessary for processing in the authentication circuit 204, and 206 is based on information output from the authentication circuit 204 Key generation for generating a key necessary for content decryption in the decryption circuit 202 207 is a timer circuit that measures the time from when information such as an authentication request is transmitted from the authentication circuit 204 to another device until reception confirmation of the information arrives. The received content is transmitted together with the content. "Copy free", "Copy one generation", "No more copies" and "Copy never" are processed according to the identification code, and "Copy free" and "Copy one generation" can be recorded on content recording media. When the “generation” content is recorded, the content is handled as “No more copies” thereafter.

  FIG. 2 shows a configuration example of a home LAN including the content transmission device 100 and the content reception device 200. One content transmission device 100 and two content reception devices 200a and 200b are connected to a network hub device 300 by a wired LAN cable, and the network hub device 300 is connected to a router 400. The router 400 is connected to the Internet via a modem or a photoelectric converter. The content transmitting device 100, the content receiving devices 200a and 200b, and the router 400 each have an IP address that identifies itself on the LAN. A 48-bit MAC (Media Access Control) address is given in advance to the interface section of each network communication processing circuit at the time of manufacture. For example, the router 400 is operated as a DHCP server by DHCP (Dynamic Host Configuration Protocol), which has been widely used for automatic address setting in the network, and the IP address of each device is set. Should be allocated. When IPv6 (Internet Protocol Version 6) is used, each device can determine its own IP address from the upper 64 bits of the IP address of the router 400 and the MAC address by a method called stateless automatic setting.

  Further, in order to limit the copyright protected content to the range of personal use, the content transmitting apparatus 100 measures RTT (Round Trip Time) when authenticating the content receiving apparatus 200a, for example, and a response is received within a specified time. If there is, it is proved that the content receiving device 200a exists in the home, and the content protected by the content receiving device 200a can be viewed. FIG. 3 shows a sequence diagram.

  The left side shows the content transmitting apparatus 100 and the right side shows the content receiving apparatus 200a. While the authentication processing sequence is operating between the content transmission device 100 and the content reception device 200a, or when the authentication processing sequence ends, the content transmission device 100 transmits a home confirmation request to the content reception device 200a. At the same time, the timer 107 is started. After receiving the home confirmation request from the content transmission device 100, the content reception device 200a transmits a home confirmation response to the content transmission device 100. The content receiving device 100 that has received the in-home confirmation response stops the timer 107, calculates the time (ΔT1) from the start of the timer, and if it is equal to or less than a certain constant (ΔT), the content receiving device 200a is a home device. And authenticate. This makes it possible to limit the copyright-protected content to the range of personal use. Conversely, a home confirmation request may be transmitted from the content receiving device 200a to the content transmitting device 100 to measure the RTT time.

  FIG. 4 shows an example of a format of data transmitted between the content transmission device 100 and the content reception device 200. Reference numeral 501 describes encryption information, and the content transmission apparatus 100 generates encryption data 502 according to the information. The content receiving apparatus 200 receives the encrypted information 501 and the encrypted data 502 via the network, and decrypts the encrypted data 502 based on the information described in the encrypted information 501. For example, in the DTCP-IP system for copyright protection, a packet called PCP (Protected Content Packets) is defined by the encryption information 501 and the encryption data 502, and the encryption information 501 is called a PCP header. This PCP header includes “Copy free”, “Copy one generation”, “No more copies”, and “Copy never” encryption modes, information that becomes part of the content key used for content encryption, and encryption data 502 Data length etc. are included.

  During data transmission from the content transmission apparatus 100 to the content reception apparatus 200, if the data does not reach the content reception apparatus 200 due to an error in the PCP header (encryption information 501), the encrypted data 502 cannot be decrypted. In the present invention, by transmitting / receiving the encryption information 501 through a path different from the path for transmitting / receiving the encryption information 501 and the encryption data 502, for example, an error occurs in the encryption information 501 so that it does not reach the content receiving apparatus 200. However, the encryption data 502 can be decrypted using the encryption information 501 obtained by another route.

FIG. 5 shows a sequence diagram when another route is performed with, for example, a TCP / IP port number.
The content transmission device 100 is shown on the left, and the content reception device 200 is shown on the right. The content transmission device 100 and the content reception device 200 are connected via two paths, a stream port and an encryption information port. Here, the stream port is a conventionally used port, and the encryption information 501 and the encryption data 502 are transmitted. The encryption information port is a port for transmitting only the packet in which the encryption information is described.

  The content transmission device 100 transmits the encryption information 501 to the content reception device 200 using the encryption information port. After receiving the encrypted information 501, the content receiving apparatus 200 holds the encrypted information 501. Next, the content transmission device 100 uses the stream port to transmit the encryption information 501 and the encryption data 502 to the content reception device 200. At this time, when a transmission error occurs and the encryption information 501 does not arrive at the content receiving apparatus 200, the encryption data 502 is decrypted using the encryption information 501 held in advance.

  If it can be normally received, the encrypted data 502 is decrypted with the encrypted information 501 received at the stream port. Here, when transmitting the encryption information using the encryption information port, the sequence number when transmitting using the stream port and the encryption information are described. As a result, the content receiving apparatus 200 can determine which encrypted data corresponds to the encrypted information that has arrived at the encrypted information port. As shown in FIG. It is not necessary to transmit the encryption information every time it is transmitted to 200, and it is also possible to transmit the encryption information collectively.

  More specifically, the encryption information 501 is transmitted using a connection-oriented type (TCP). If transmission of the encryption information 501 is performed in a connectionless manner (UDP), there is a possibility that the route is congested during the stream processing and an IP packet in which the encryption information is described is lost.

For example, RTP (Realtime Transport Protocol) is used when transmitting content with real-time properties. Since RTP is connectionless, packet loss occurs. Therefore, in the present invention, the encryption information 501 described in the first embodiment is transmitted using RTCP (RTP Control Protocol) for controlling RTP.
The sequence number and encryption information described in the first embodiment are described in the RTCP APP area. The RTCP is transmitted / received between the content transmitting apparatus 100 and the content receiving apparatus 200 during RTP transmission, and the content receiving apparatus 200 obtains the effect shown in the first embodiment by making an error in the RTP transmission path. Needless to say.

In the second embodiment, the content transmission device 600 and the content reception device 700 transmit content using a wireless LAN. FIG. 6 shows a content transmission / reception apparatus via a wireless LAN. Wireless network communication processing circuits 603 and 703 are used for connection to the LAN, and WEP (Wired Equivalent Privacy) encryption processing circuits 608 and 708 are provided. WEP is a known encryption method that is used as a standard for the purpose of security protection in a wireless LAN, and communication with security protection between a transmission device and a reception device can be realized under user management. FIG. 7 shows an example of the configuration of a home network using the content transmitting device 600 and the content receiving device 700.
In FIG. 7, a data transmission device 600 and two data reception devices 700 a and 700 b are connected by a wireless access point 800 via a wireless LAN. The wireless LAN access point 800 is further connected to the router 400, and the router 400 is connected to the Internet in the same manner as the router 400 shown in FIG.

  When mutual authentication and subsequent content transmission are to be performed between the content transmitting apparatus 600 and the content receiving apparatus 700 shown in FIG. 6, the WEP encryption processing circuits 608 and 708 perform WEP processing by the authentication circuits 604 and 704. Check to see if it has been applied. If the WEP processing is not used, mutual authentication and subsequent content transmission are not performed, or necessary processing such as a display prompting the user to start the WEP processing is performed. To do.

  As described above, when content is transmitted using a wireless LAN, the WEP processing is always performed. As a result, it is possible to prevent unauthorized copying of content by connecting another data receiving device via a wireless LAN without the user of the content transmitting device 600 and the content receiving device 700 being conscious. With respect to points other than those described above, the content video can be reproduced without stopping in exactly the same manner as the content transmission method implemented by the content transmission device and content reception device described in the first embodiment. is there. In addition, copyright protection can be performed, and at this time, it is possible to prevent transmission of content that deviates from the range of personal use.

  The third embodiment is to optimally adjust the size of the IP packet transmitted from the content transmission apparatus 100. For example, content encryption in DTCP-IP is performed in the CBC (Cipher Block Chaining) mode of the AES-128 algorithm. FIG. 8 shows the size configuration of the IP packet. (A) shows a normal IP packet size, and (b) shows an IP packet size of the present invention. Here, the MTU (Maximum Transfer Unit) value is set to a predetermined 1500 octet. When transmission / reception of encrypted data is performed using a normal IP packet, if the encrypted data does not arrive at the content receiving apparatus 200 due to an error, the process of decrypting the encrypted data that arrives next becomes complicated. In the IP packet transfer method of the present invention, when the encrypted data does not arrive at the content receiving device 200 due to the occurrence of an error, the encrypted data is transferred at the 16-byte boundary, so the first 16 bytes of the next received encrypted data are used as the initial value. Can be decrypted. For this reason, in this embodiment, even if the encrypted data is lost on the way due to an error, the content receiving apparatus 200 can immediately decrypt the encrypted data that arrives next.

In this embodiment, the case where a predetermined value (1500 octets) is used as the MTU has been described. However, by setting the MTU value to an optimum value (1496 octets in this embodiment), the padding process can be performed. Needless to say, the same effect as described above can be obtained.
As described above, according to the present invention, it is possible to solve the problem that the reproduction of content stops when a packet is lost on the network due to line congestion or the like, and it is possible to reproduce the video early even if the video is stopped.

  When content is transmitted using a wired or wireless LAN in the house, it is possible to solve the problem that the video reproduction process is stopped due to a content data error.

The figure which shows the structure using the wired LAN of the content transmission apparatus by the Example of this invention, and a content reception apparatus. 1 is a block diagram of a wired LAN composed of a content transmission device and a content reception device according to an embodiment of the present invention. The RTT process sequence diagram of the Example of this invention. The figure which shows the format of the data transmitted between the content transmitter by the Example of this invention, and a content receiver. The sequence diagram of the data transmission of the Example of this invention. The figure which shows the structure using the wireless LAN of the content transmitter by the Example of this invention, and a content receiver. 1 is a block diagram of a wireless LAN composed of a content transmission device and a content reception device according to an embodiment of the present invention. The IP packet block diagram of the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100, 600 ... Content transmission apparatus 101, 601 ... Content transmission circuit 102, 602 ... Encryption circuit 103, 603 ... Network communication processing circuit 104, 604 ... Authentication circuit 105, 605 ... Non-volatile memory 106, 606 ... Key generation circuit 107 , 607 ... Timer circuits 200 and 700 ... Content receiving devices 201 and 701 ... Content receiving circuits 202 and 702 ... Decryption circuits 203 and 703 ... Network communication processing circuits 204 and 704 ... Authentication circuits 205 and 705 ... Non-volatile memories 206 and 706 ... key generation circuits 207 and 707 ... timer circuit 300 ... network hub device 400 ... router 500 ... transmission data 800 ... wireless access point

Claims (8)

Network communication processing means for transmitting and receiving data via a network;
Content generating means for supplying content to be transmitted to a content receiving apparatus connected via the network to the network communication means;
An authentication unit that receives an authentication request from the content receiving device, determines authentication for the authentication request, and issues its own authentication request to the content receiving device;
Encryption means for generating key information from information generated based on information obtained by executing authentication processing by the authentication means, and encrypting content to be transmitted to the content receiving device using the key information;
Timer means for measuring the time until the reception of the reception confirmation from the content receiving device with respect to the transmission of the authentication request to the content receiving device or the transmission of the response to the authentication request from the content receiving device;
A route different from the route used when transmitting the encryption information and encrypted data used for encryption to the content receiving device is secured with the content receiving device, and the route for securing the encryption information is secured. A content transmission apparatus characterized by being transmitted to a content reception apparatus.   2. The content transmitting apparatus according to claim 1, wherein when the encrypted information and the encrypted data used for encryption are transmitted to the content receiving apparatus through a connectionless connection, the encrypted information is transmitted through a connection-oriented connection. A content transmitting apparatus characterized by transmitting to the content.   2. The content transmitting apparatus according to claim 1, wherein when the encrypted information and encrypted data used for encryption are transmitted to the content receiving apparatus by RTP, the encrypted information is described in a part of RTCP that controls the RTP. The content transmission apparatus characterized by transmitting. Network communication processing means for transmitting and receiving data via a network;
Content reception processing means for receiving content received from a content transmission apparatus connected via the network, the network communication means;
An authentication unit that issues and sends an authentication request to the content transmission device and performs authentication determination for the authentication request received from the content transmission device;
Decryption means for generating key information based on information generated based on information obtained by executing authentication processing by the authentication means, and for decrypting content received from the content transmission device using the key information;
Timer means for measuring a time until arrival of a reception confirmation from the content transmission device with respect to transmission of an authentication request to the content transmission device or transmission of a response to the authentication request from the content transmission device;
A route different from the route for receiving encrypted information and encrypted data transmitted from the content transmitting device is secured with the content transmitting device, and only the encrypted information is received using the secured route. A featured content receiver.   5. The content receiving apparatus according to claim 4, wherein when the encrypted information and the encrypted data are received from the content transmitting apparatus by connectionless connection, the encrypted information is received from the content transmitting apparatus by connection-oriented connection. A featured content receiver.   5. The content receiving apparatus according to claim 4, wherein when the encrypted information and the encrypted data are received from the content transmitting apparatus by RTP, the encrypted information is received by RTCP that controls RTP. .   4. The content transmitting apparatus according to claim 1, wherein the encrypted information and the encrypted data are transmitted to the content receiving apparatus via the network with an optimum number of bytes for decryption. Transmitter device. 7. The content receiving apparatus according to claim 4, wherein the encrypted information and the encrypted data are received from the content transmitting apparatus via the network with an optimum number of bytes for decryption. apparatus.

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