Patent Publication Number: US-2010121966-A1

Title: Repeater and repeating method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2008-287189, filed Nov. 7, 2008, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field 
     One embodiment of the invention relates to a repeater that relays content data protected by copyright, and a repeating method thereof. 
     2. Description of the Related Art 
     In recent years, with improvements in such technologies as compression coding, encryption, and communication, movies and music are digitalized into content data and such content data is communicated via a network. Content data of this type is often protected by copyright. Accordingly, there has been proposed various technologies for eliminating unauthorized devices that are highly likely to infringe copyright by, for example, making an illegal copy of protected content. 
     According to digital transmission content protection (DTCP), before communication of content data between devices connected to each other, the devices are authenticated based on identification information that identifies DTCP devices. If the authentication is successful, encrypted content data is communicated between the devices. With this, content data can be communicated only between authorized devices capable of valid communication of content data. Reference may be had to, for example, Digital Transmission Content Protection Specification Revision 1.51 (Informational Version), pp. 55 to 64, Chapter 8, AV/C Digital Interface Command Set Extensions. 
     Similarly, according to high-bandwidth digital content protection (HDCP), before communication of content data between devices connected to each other, the devices are authenticated based on identification information that identifies HDCP devices. If the authentication is successful, encrypted content data is communicated between the devices. 
     In the HDCP scheme, it is not possible to communicate identification information that identifies devices complying with other copyright protection schemes (such as DTCP). For example, it is assumed that a pair of repeaters compliant with DTCP relay communication of content data protected by HDCP between devices. In this case, even if a repeater on the receiving side is an unauthenticated device, identification information that identifies the repeater cannot be sent to the transmitting side, and therefore the repeater cannot be removed. Consequently, the transmitter device cannot be prevented from transmitting the content data to the unauthenticated device. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A general architecture that implements the various features of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention. 
         FIG. 1  is an exemplary block diagram of a content transfer system including a repeater, a source device, and a sink device according to an embodiment of the invention; 
         FIG. 2  is an exemplary flowchart of a list creation process performed by the repeater in the embodiment; 
         FIG. 3  is an exemplary flowchart of an authentication process performed by the source device in the embodiment; 
         FIG. 4  is an exemplary block diagram of a hardware configuration of the repeater in the embodiment; and 
         FIG. 5  is an exemplary block diagram of a hardware configuration of the source device and the sink device in the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, a repeater receives content data from a sender device through a first content protection technology and transmits the content data to another device through a second content protection technology. The repeater comprises a receiver, a preparation module, and a transmitter. The receiver is configured to receive identification information that identifies a device compliant with the second content protection technology through the second content protection technology. The preparation module is configured to prepare an identification information list based on the first content protection technology that contains the identification information based on the second content protection technology received by the receiver and identification information based on the first content protection technology that identifies the repeater. The transmitter is configured to transmit the identification information list to the sender device through the first content protection technology. 
     According to another embodiment of the invention, a repeating method is applied to a repeater that receives content data from a sender device through a first content protection technology and transmits the content data to another device through a second content protection technology. The repeating method comprises: a receiver receiving identification information that identifies a device compliant with the second content protection technology through the second content protection technology; a preparation module preparing an identification information list based on the first content protection technology that contains the identification information based on the second content protection technology received by the receiver and identification information based on the first content protection technology that identifies the repeater; and a transmitter transmitting the identification information list to the sender device through the first content protection technology. 
     With reference to  FIG. 1 , a description will be given of a content transfer system including repeaters, a source device, and a sink device according to an embodiment of the invention. Although the embodiment describes the case where the repeaters, such as wireless local area network (LAN) routers, relay communication between the source device and the sink device such as personal computers, this is by way of example and not by way of limitation. For example, the repeaters may relay communication of content data between AV devices (for example, a hard disk recorder and a digital television, or the like) connected therethrough to each other.  FIG. 1  is a block diagram of a content transfer system  100  including a repeater A  102 , a repeater B  103 , a source device  101 , and a sink device  104  according to the embodiment. 
     The content transfer system  100  comprises the source device  101 , the sink device  104 , the repeater A  102 , and the repeater B  103 . The source device  101  transmits content data such as video data and audio data. The sink device  104  receives the content data transmitted from the source device  101 . The repeater A  102  and the repeater B  103  relay the content data between the source device  101  and the sink device  104 . It is assumed herein that the source device  101  and the repeater A  102  are connected by a wired network such as a high-definition multimedia interface (HDMI), and similarly, that the sink device  104  and the repeater B  103  are connected by a wired network. It is also assumed herein that the repeater A  102  and the repeater B  103  are connected by a wireless network such as Wi-Fi. 
     Described below is a configuration of the sink device  104 . The sink device  104  receives from the repeater B  103  content data protected by high-bandwidth digital content protection (HDCP), which is a first content protection technology (CPT  1 ). 
     The sink device  104  comprises a transmitter/receiver (CPT  1 )  104   a.    
     The transmitter/receiver  104   a  is an interface to the repeater B  103  and is compliant with HDCP, i.e., an interface with CPT  1  for communication with the repeater B  103 . Through the wired network that connects between the sink device  104  and the repeater B  103 , the transmitter/receiver  104   a  receives content data protected by CPT  1  from the repeater B  103 . 
     Before receiving the content data, the transmitter/receiver  104   a  transmits identification information (Bksv 2 ) based on CPT  1 , which uniquely identifies the sink device  104 , to the repeater B  103  through CPT  1 . Upon transmitting the identification information (Bksv 2 ) to the repeater B  103 , the transmitter/receiver  104   a  may encrypt the identification information (Bksv 2 ) and transmit the encrypted identification information (Bksv 2 ) to the repeater B  103 . Alternatively, the transmitter/receiver  104   a  may transmit the identification information (Bksv 2 ) to the repeater B  103  with an electronic signature to verify the identification information (Bksv 2 ). 
     Described below is a configuration of the repeater B  103 . The repeater B  103  transfers content data to the sink device  104  through CPT  1 . The content data is protected by digital transmission content protection (DTCP) or digital transmission content protection-internet protocol (DTCP-IP), which is a second content protection technology (CPT  2 ). 
     The repeater B  103  comprises a transmitter/receiver (CPT  2 )  103   a , a creation module  103   b , and a transmitter/receiver (CPT  1 )  103   c.    
     The transmitter/receiver  103   c  is an interface to the sink device  104  and is compliant with HDCP, i.e., an interface with CPT  1  for communication with the sink device  104 . Through the wired network that connects between the repeater B  103  and the sink device  104 , the transmitter/receiver  103   c  transmits content data protected by CPT  1  to the sink device  104 . 
     Before transmitting the content data, the transmitter/receiver  103   c  receives the identification information (Bksv 2 ) based on CPT  1 , which uniquely identifies the sink device  104 , from the sink device  104  through CPT  1 . 
     When the identification information (Bksv 2 ) received from the sink device  104  is contained in an unauthorized device list stored in a storage medium that the repeater B  103  is provided with, the transmitter/receiver  103   c  does not transmit the content data to the sink device  104 . However, the embodiment is not so limited. For example, the repeater B  103  may not necessarily have the function of terminating transmission of content data if at least the source device  101  has that function. In this case, when a list  112 , which will be described later, received from the repeater A  102  contains identification information that matches the one contained in the unauthorized device list, the source device  101  terminates transmission of content data. 
     The creation module  103   b  prepares a list  110  that contains the identification information (Bksv 2 ) received by the transmitter/receiver  103   c.    
     The transmitter/receiver  103   a  is an interface to the repeater A  102  and is compliant with DTCP, i.e., an interface with CPT  2  for communication with the repeater A  102 . Through the wireless network that connects between the repeater A  102  and the repeater B  103 , the transmitter/receiver  103   a  receives content data protected by CPT  2  from the repeater A  102 . 
     Before receiving the content data, the transmitter/receiver  103   a  transmits the list  110  created by the creation module  103   b  and identification information (D-id 2 ) based on CPT  2 , which uniquely identifies the repeater B  103 , to the repeater A  102  through CPT  2 . The transmitter/receiver  103   a  may be capable of receiving from the repeater A  102  a list (not illustrated) that contains identification information (Aksvl) based on CPT  1 , which uniquely identifies the source device  101 , and identification information (D-id 1 ) based on CPT  2 , which uniquely identifies the repeater A  102 . 
     Upon transmitting the list  110  and the identification information (D-id 2 ) to the repeater A  102 , the transmitter/receiver  103   a  may encrypt the list  110  and the identification information (D-id 2 ) and transmit the encrypted list  110  and identification information (D-id 2 ) to the repeater A  102 . Alternatively, the transmitter/receiver  103   a  may transmit the list  110  and the identification information (D-id 2 ) with an electronic signature to verify the list  110  and the identification information (D-id 2 ). 
     Described below is a configuration of the repeater A  102 . The repeater A  102  receives content data protected by CPT  1  from the source device  101 , and transfers the content data to the repeater B  103  through CPT  2 . 
     The repeater A  102  comprises a transmitter/receiver (CPT  1 )  102   a , a creation module  102   b , and a transmitter/receiver (CPT  2 )  102   c.    
     The transmitter/receiver  102   c  is an interface to the repeater B  103  and is compliant with DTCP, i.e., an interface with CPT  2  for communication with the repeater B  103 . Through the wireless network that connects between the repeater A  102  and the repeater B  103 , the transmitter/receiver  102   c  transmits content data protected by CPT  2  to the repeater B  103 . 
     Before transmitting the content data, the transmitter/receiver  102   c  receives the identification information (D-id 2 ) based on CPT  2  unique to the repeater B  103  and the list  110  from the repeater B  103  through CPT  2 . The list  110  contains the identification information (Bksv 2 ) based on CPT  1  unique to the sink device  104 . The transmitter/receiver  102   c  may be capable of transmitting identification information (D-id 1 ) based on CPT  2 , which uniquely identifies the repeater A  102 , to the repeater B  103  through CPT  2 . 
     When any of the identification information (Bksv 2 ) contained in the list  110  and the identification information (D-id 2 ) received from the repeater B  103  matches the one contained in an unauthorized device list stored in a storage medium that the repeater A  102  is provided with, the transmitter/receiver  102   c  does not transmit the content data to the repeater B  103 . However, the embodiment is not so limited. For example, the repeater A  102  may not necessarily have the function of terminating transmission of content data if at least the source device  101  has that function. In this case, when the list  112 , which will be described later, received from the repeater A  102  contains identification information that matches the one contained in the unauthorized device list, the source device  101  terminates transmission of content data. 
     The creation module  102   b  creates the list  112  based on CPT  1 . More specifically, the creation module  102   b  adds identification information (Bskv 1 ) based on CPT  1 , which uniquely identifies the repeater A  102 , to a list  111  that contains the identification information (Bksv 2 ) contained in the list  110  and the identification information (D-id 2 ) received by the transmitter/receiver  102   c  to create the list  112 . 
     The transmitter/receiver  102   a  is an interface to the source device  101  and is compliant with HDCP, i.e., an interface with CPT  1  for communication with the source device  101 . Through the wired network that connects between the source device  101  and the repeater A  102 , the transmitter/receiver  102   a  receives content data protected by CPT  1  from the source device  101 . 
     Before receiving the content data, the transmitter/receiver  102   a  transmits the list  112  created by the creation module  102   b  to the source device  101  through CPT  1 . Upon transmitting the list  112  created by the creation module  102   b  to the source device  101 , the transmitter/receiver  102   a  may encrypt the list  112  and transmit the encrypted list  112  to the source device  101 . Alternatively, the transmitter/receiver  102   a  may transmit the list  112  with an electronic signature to verify the list  112 . 
     Described below is a configuration of the source device  101 . The source device  101  transmits content data protected by CPT  1  to the repeater A  102 . 
     The source device  101  comprises a determination module  101   a  and a transmitter/receiver (CPT  1 )  101   b.    
     The transmitter/receiver  101   b  is an interface to the repeater A  102  and is compliant with HDCP, i.e., an interface with CPT  1  for communication with the repeater A  102 . Through the wired network that connects between the source device  101  and the repeater A  102 , the transmitter/receiver  101   b  transmits content data protected by CPT  1  to the repeater A  102 . 
     Before transmitting the content data, the transmitter/receiver  101   b  receives the list  112  from the repeater A  102  through CPT  1 . 
     The determination module  101   a  determines whether any of identification information (Bksv 1 , D-id 2 , and Bksv 2 ) contained in the list  112  received by the transmitter/receiver  101   b  matches the one contained in an unauthorized device list stored in a storage medium that the source device  101  is provided with. 
     When the determination module  101   a  determines that none of the identification information (Bksv 1 , D-id 2 , and Bksv 2 ) contained in the list  112  matches the one contained in the unauthorized device list, the transmitter/receiver  101   b  transmits the content data protected by CPT  1 . 
     With reference to  FIG. 2 , a description will now be given of the process of creating the list  111  performed by the repeater A  102 . Incidentally, the repeater B  103  creates the list  110  in the same manner as the repeater A  102  creates the list  111 , and the description will not be repeated. Further, with reference to  FIG. 3 , a description will be given of an authentication process performed by the source device  101 .  FIG. 2  is a flowchart of the list creation process performed by the repeater A  102 .  FIG. 3  is a flowchart of the authentication process performed by the source device  101 . 
     First, the list creation process performed by the repeater A  102  will be described with reference to  FIG. 2 . Before transmitting content data, the transmitter/receiver  102   c  receives the list  110  from the repeater B  103  through CPT  2  (S 201 ) The list  110  contains the identification information (Bksv 2 ) based on CPT  1  that identifies the sink device  104 . When the transmitter/receiver  102   c  receives the identification information (D-id 2 ) based on CPT  2  that identifies the repeater B  103  from the repeater B  103  through CPT  2  (Yes at S 202 ), the creation module  102   b  creates the list  111  that contains the identification information (Bksv 2 ) contained in the list  110  and the identification information (D-id 2 ) received by the transmitter/receiver  102   c  (S 203 ). 
     On the other hand, when the transmitter/receiver  102   c  does not receive the identification information (D-id 2 ) based on CPT  2  that identifies the repeater B  103  (No at S 202 ), the creation module  102   b  add the identification information (Bskv 1 ) based on CPT  1  that identifies the repeater A  102  to the list  110  or the list  111  to create the list  112  based on CPT  1  (S 204 ). Besides, after creating the list  111  (S 203 ), the creation module  102   b  also creates the list  112  that further contains the identification information (Bksv 1 ) identifying the repeater A  102  (S 204 ). 
     Next, the authentication process performed by the source device  101  will be described with reference to  FIG. 3 . Before transmitting content data, the transmitter/receiver  101   b  receives the list  112  from the repeater A  102  through CPT  1  (S 301 ). Thereafter, the determination module  101   a  determines whether any of identification information (Bksv 1 , D-id 2 , and Bksv 2 ) contained in the list  112  received by the transmitter/receiver  101   b  matches the one contained in the unauthorized device list stored in the storage medium that the source device  101  is provided with (S 302 ) When it is determined that none of the identification information (Bksv 1 , D-id 2 , and Bksv 2 ) contained in the list  112  matches the one contained in the unauthorized device list (No at S 301 ), the transmitter/receiver  101   b  transmits the content data protected by CPT  1  to the repeater A  102  (S 303 ). On the other hand, when it is determined that any of the identification information (Bksv 1 , D-id 2 , and Bksv 2 ) contained in the list  112  matches the one contained in the unauthorized device list (Yes at S 301 ), the transmitter/receiver  101   b  terminates transmission of the content data (S 304 ). 
     With reference to  FIG. 4 , a description will then be given of a hardware configuration of the repeater A  102  and the repeater B  103  of the embodiment.  FIG. 4  is a block diagram of the hardware configuration of the repeater A  102  and the repeater B  103 . 
     As illustrated in  FIG. 4 , the repeater A  102  and the repeater B  103  may be, for example, wireless LAN routers and each comprise a central processing unit (CPU)  401 . The CPU  401  is the main element of the wireless LAN router and controls the constituent elements thereof. The repeater A  102  and the repeater B  103  each further comprise a read only memory (ROM)  402  and a random access memory (RAM)  403 , which are connected to the CPU  401  via a bus  404 . The ROM  402  stores BIOS and the like, while the RAM  403  is rewritable and stores various types of data. 
     Since the RAM  403  stores various types of data in a rewritable manner, it provides a work area to the CPU  401  and functions as a buffer or the like. 
     The ROM  402  stores an operating system (OS) and various programs. The programs may run on the OS and, in this case, the OS may perform part of various types of processing implemented by the programs. Further, the programs may be stored as part of a group of program files that constitutes predetermined application software, the OS, or the like. 
     The ROM  402  also stores the identification information based on CPT  1  that identifies the repeater (the repeater A  102  or the repeater B  103 ) as well as the identification information based on CPT  2  that identifies the repeater. It is assumed herein that the identification information based on CPT  1  and that based on CPT  2  have the same data length. 
     The CPU  401  controls the overall operation of the system, and performs various types of processing based on the programs stored in the ROM  402  used as the main storage device of the system. 
     According to the various programs stored in the ROM  402 , the creation module  102   b  and the creation module  103   b  are implemented on the repeater A  102  and the repeater B  103 , respectively. 
     With reference to  FIG. 5 , a description will then be given of a hardware configuration of the source device  101  and the sink device  104  of the embodiment.  FIG. 5  is a block diagram of the hardware configuration of the source device  101  and the sink device  104 . 
     As illustrated in  FIG. 5 , the source device  101  and the sink device  104  may be, for example, personal computers and each comprise a CPU  501 . The CPU  501  is the main element of the personal computer and controls the constituent elements thereof. The source device  101  and the sink device  104  each further comprise a ROM  502  and a RAM  503 , which are connected to the CPU  501  via a bus  504 . The ROM  502  stores BIOS and the like, while the RAM  503  is rewritable and stores various types of data. 
     The source device  101  and the sink device  104  each further comprise a hard disk drive (HDD)  505 , a compact disc read only memory (CD-ROM)  506 , a CD-ROM drive  507 , an input module  508 , a display module  509 , and an audio output module  510 . The HDD  505  stores various programs and content data including audio data and video data. The CD-ROM  506  stores computer software which is a distributed program. The CD-ROM drive  507  reads the computer software from the CD-ROM  506 . The input module  508  includes a keyboard, a mouse, and the like used to provide various instructions. The display module  509  includes a cathode ray tube (CRT) or a liquid crystal display (LCD) to display various types of video data. The audio output module  510  includes a speaker for outputting audio data and a headphone. The above modules are also connected to the bus  504  via an I/O (not illustrated). 
     Since the RAM  503  stores various types of data in a rewritable manner, it provides a work area to the CPU  501  and functions as a buffer or the like. The RAM  503  also stores the identification information based on CPT  1  that identifies the device (the source device  101  or the sink device  104 ). 
     The CD-ROM  506  stores an OS and various programs. Besides, the CD-ROM  506  of the source device  101  stores the unauthorized device list that contains identification information identifying an unauthorized device based on CPT  1  and also identification information identifying an unauthorized device based on CPT  2 . The CD-ROM drive  507  reads the programs and the unauthorized device list from the CD-ROM  506  under the control of the CPU  501 . Then, the programs and the unauthorized device list are installed on the HDD  505 . 
     While the CD-ROM  506  is cited above as an example of a storage medium of the embodiment, the storage medium may be of different types. Examples of the storage medium of the embodiment include various types of optical disks such as a digital versatile disk (DVD), various types of magneto-optical discs, various types of magnetic disks such as a flexible disk, and semiconductor memory. Alternatively, the programs and the unauthorized device list may be downloaded via a network (not illustrated) and installed on the HDD  505 . In this case, a sender server that stores the programs and the unauthorized device list can be regarded as the storage medium of the embodiment. Incidentally, the programs may run on a predetermined OS and, in this case, the OS may perform part of various types of processing implemented by the programs. Further, the programs may be stored as part of a group of program files that constitutes predetermined application software, the OS, or the like. 
     The CPU  501  controls the overall operation of the system, and performs various types of processing based on the programs loaded into the HDD  505  used as the main storage device of the system. According to the programs installed on the HDD  505 , the source device  101  implements the determination module  101   a.    
     As described above, according to the embodiment, the repeater A  102  can authenticate a device connected via the repeater A  102  to the source device  101  using the unauthorized device list stored in the source device  101  regardless of the type of content protection technology. Thus, content data can be reliably prevented from being transmitted to an unauthorized device connected via the repeater A  102  to the source device  101 . 
     The various modules of the systems described herein can be implemented as software applications, hardware and/or software modules, or components on one or more computers, such as servers. While the various modules are illustrated separately, they may share some or all of the same underlying logic or code. 
     While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.