JP2007067929A - Communication apparatus, digital television set, and communication apparatus control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication apparatus which achieves appropriate operation control according to the situation. <P>SOLUTION: A digital TV set 1 and an HDD recorder 2 are DTCP-IP enabled apparatuses and transmit/receive copyright-protected contents via an IP network. When performing special playback called fast-forwarding, the digital TV set 1 reduces the frequency of content requests, to the HDD recorder 2, that cause updating of a content key or stops the next content request until the end of content key confirmation processing with the HDD recorder 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an operation control technique for a communication device that receives copyright-protected content from another communication device via an IP network.

With recent improvements in compression encoding technology, encryption technology, communication technology, etc., it has begun to transmit and receive content obtained by digitizing movies, music, etc. via a network. Since this type of content is often protected by copyright, various techniques have been proposed for eliminating illegal devices that are likely to carry out copyright infringement activities such as illegal copying (for example, For example, see Patent Document 1).
JP 2000-287192 A

  DTCP (Digital Transmission Content Protection) is a copyright protection technique used when content is transmitted and received by an interface for establishing a data transmission path between two communication devices such as IEEE1394 and USB. In DTCP, each device has a device certificate issued by DTLA (Digital Transmission Licensing Administrator), which is a licensing organization, and when transmitting content, this device certificate is mutually verified, and authentication and key exchange are performed. The encryption key is shared. Further, DTCP-IP is a technology that extends this DTCP technology so that it can be used on an IP (Internet Protocol) network.

  A specification newly added in DTCP-IP includes content key confirmation (CKC). This is for confirming that a device that has performed authentication key exchange (AKE: Device Authentication and Key Exchange) is associated with a stream that is currently transmitted by the device.

  The reason why this CKC does not succeed is that the received content key (Nc) is different from the transmitted Nc (because the AKE device is different from the device that sends the stream due to the presence of a relay device or the like). And the case where the key (Kx) shared after AKE is not correct is considered, and it is desirable to change the coping method and the notification method to the user depending on each case.

  However, there is a problem that it is not possible to specify the multiple causes by CKC alone. If CKC fails due to the above-mentioned Kx mismatch, no matter how many times CKC is tried, it will not succeed, so decoding must be stopped within 1 minute according to the standard.

  Also, in situations where content partial acquisition requests occur frequently, such as during special playback such as fast-forward playback, the content encryption / decryption parameter (Nc) is frequently changed. The Nc you are doing may not match. At that time, the CKC fails, and as a result, there is a problem that the decoding must be stopped even if the AKE device and the device sending the stream are the same.

  The present invention has been made in consideration of such circumstances, and provides a communication device, a digital television device, and a communication device control method that realizes appropriate operation control according to the situation. Objective.

  In order to achieve the above-described object, a communication device according to the present invention is a communication device that receives content having a content key from another communication device via an IP network. An authentication key exchanging unit that acquires an authentication key for identifying the other communication device and authenticating the content key of the content received via the IP network to the other communication device that has been authenticated by the authentication key exchanging unit Content key confirming means for confirming whether or not the received content is acquired from the other communication apparatus authenticated by the authentication key exchanging means in response to the transmission from the other communication apparatus. As a result of confirmation by the content key confirmation unit, the other communication device in which the received content is authenticated by the authentication key exchange unit A first control for re-executing the authentication key exchanging means and determining whether or not the authentication key acquired by the re-execution and the authentication key before the re-execution are the same; If it is determined by the first control that the authentication keys are not the same, the content key confirmation unit is re-executed, and the received content is obtained from the other communication device authenticated by the authentication key exchange unit A second control for determining whether or not the content received by the second control is not acquired from the other communication device, and a third control for stopping reception of the content. And a control means.

  The communication apparatus according to the present invention is a communication apparatus that receives content having a content key updated at a predetermined timing from another communication apparatus via an IP network. An authentication key exchanging unit that acquires an authentication key for identifying the other communication device and authenticating the content key of the content received via the IP network to the other communication device that has been authenticated by the authentication key exchanging unit Content key confirming means for confirming whether or not the received content is acquired from the other communication apparatus authenticated by the authentication key exchanging means in response to the transmission from the other communication apparatus. , Receiving the content more than a predetermined number of times within a predetermined time for the other communication device authenticated by the authentication key exchange means When the fast-forward playback request to perform seek, characterized by comprising a control means for reducing the frequency of the received request for the content to confirmation by the content key confirmation means has finished.

  According to the present invention, it is possible to provide a communication device, a digital television device, and a communication device control method that realizes appropriate operation control according to the situation.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
First, a first embodiment of the present invention will be described. FIG. 1 is a diagram illustrating a usage example of the communication device according to the first embodiment. Here, the communication apparatus of the present invention is realized as a digital television (TV) apparatus.

  The digital TV device 1 is a DTCP-IP compatible device having a function of receiving and reproducing copyright-protected content via an IP network, and acquires the content held by the HDD recorder 2 via the router 3. That is, the digital TV apparatus 1 operates as a sink device and the HDD recorder 2 operates as a source device, and performs TCP / IP communication between the two. The router 3 interposed between the digital TV device 1 and the HDD recorder 2 may be a personal computer having a routing function, for example.

  FIG. 2 is a block diagram showing a schematic configuration of a portion related to content acquisition of the digital TV apparatus 1.

  As shown in FIG. 2, the digital TV apparatus 1 includes a user interface unit 11, a DTCP-IP transfer unit 12, an AKE unit 13, a calculation unit 14, a PCP (Protected Content Packet) unit 15, and a socket 16.

  When the digital TV device 1 operating as a sink device receives copyright-protected content from the HDD recorder 2 of the source device via the IP network, an authentication key exchange process called AKE is performed with the HDD recorder 2. Need to run. The authentication key exchange process executed by the digital TV device 1 with the HDD recorder 2 acquires an authentication key for identifying the HDD recorder 2 from the HDD recorder 2, authenticates the HDD recorder 2, and identifies the device 1 itself. An authentication key to be transmitted is transmitted to the HDD recorder 2 to cause the HDD recorder 2 to authenticate the device 1 itself. The DTCP-IP transfer unit 12 controls the entire communication related to the exchange of contents with the HDD recorder 2 and instructs the AKE unit 13 to execute this authentication key exchange process. The DTCP-IP transfer unit 12 also executes interface processing with the upper module.

  Upon receiving an instruction from the DTCP-IP transfer unit 12, the AKE processing unit 13 executes an authentication key exchange process with the HDD recorder 2 via the socket 16, and at this time, verification of the acquired authentication key, etc. Is requested to the calculation unit 14. When the notification that the verification of the authentication key is successful is returned from the calculation unit 14, the AKE processing unit 13 notifies the DTCP-IP transfer unit 12 of the success of the authentication key exchange process.

  When this notification is received from the AKE processing unit 13, the DTCP-IP transfer unit 12 receives the content from the HDD recorder 2 via the socket 16. Since the content is encrypted and transmitted, the DTCP-IP transfer unit 12 requests the PCP unit 15 to decrypt the encrypted content. When the PCP unit 15 receives this request from the DTCP-IP transfer unit 12, the PCP unit 15 acquires the authentication key of the HDD recorder 2 from the AKE unit 13, and decrypts the content using the authentication key.

  The DTCP-IP transfer unit 12 requests the AKE unit 13 to confirm the content key added as a parameter to the content in parallel with the decryption of the content. In the content key confirmation process executed by the digital TV apparatus 1 with the HDD recorder 2, the content key added to the content is transmitted to the HDD recorder 2, and the content is transferred to the HDD by the response from the HDD recorder 2 to this transmission. This is to confirm whether or not it is obtained from the recorder 2. Upon receiving this request, the AKE unit 13 executes a content key confirmation process with the HDD recorder 2, and a content key added to the content and a content key added to the content being transmitted by the HDD recorder 2 To see if they match. This result is notified to the DTCP-IP transfer unit 12, and if it matches, it can be determined that the content is transmitted from the HDD recorder 2 authenticated by the authentication key exchange process. The unit 12 continues the content reception process as it is. On the other hand, if they do not match, the DTCP-IP transfer unit 12 stops the content reception processing because there is a possibility that the content is transmitted from an unauthorized device (for example, illegal copying is performed between the two). .

  When the DTCP-IP transfer unit 12 transmits copyright-protected content, the PCP unit 15 also creates a packet for storing the content. At that time, the PCP unit 15 requests the AKE unit 13 to generate a cryptographic parameter to be set in this packet, and the AKE unit 13 that has received this request calculates a cryptographic parameter that can be decrypted with the authentication key of the digital TV apparatus 1. The data is generated by the unit 14 and returned to the PCP unit 15. The packet in which the encryption parameter is set is transmitted to the transmission partner by the DTCP-IP transfer unit 12.

  According to the above flow, the digital TV apparatus 1 acquires and uses the copyright-protected content from the HDD recorder 2, but in DTCP-IP, the above-described content key is used as a specification for preventing the intervention of unauthorized devices. Defines confirmation. Therefore, the digital TV apparatus 1 that is a sink device and the HDD recorder 2 that is a source device perform communication in the procedure shown in FIG. That is, first, communication for authentication key exchange is performed ((1) in FIG. 3), and after that, communication for content transmission / reception is performed ((2) in FIG. 3). Communication for confirmation is executed ((3) in FIG. 3).

  By performing communication in such a procedure, for example, as shown in FIG. 4, it is possible to prevent the unauthorized device 4 that illegally takes in the content between the digital TV device 1 and the HDD recorder 2 (in the intervened state). Send and receive content for.

  By the way, as a case where the content key confirmation fails, there may be a case where the authentication key of the HDD recorder 2 is updated after the authentication key exchange due to some factor other than the intervention of the unauthorized device 4 as shown in FIG. This is because when the authentication key of the HDD recorder 2 is updated, the content key added to the content transmitted by the HDD recorder 2 is also updated. Therefore, when content key confirmation fails, it is necessary to take appropriate measures according to the cause. Therefore, in the digital TV apparatus 1 according to the first embodiment, when the content key confirmation process fails, the authentication key exchange process is re-executed, and whether or not the authentication key has been updated is identified to identify the cause of the failure of the content key confirmation process. To do.

If the authentication key has been updated after the authentication key exchange process, the content key confirmation process is re-executed assuming that the authentication key is different as the cause of the failure of the content key confirmation process. On the other hand, if the authentication key has not been updated, it is confirmed that the content received by the digital TV device 1 and the HDD recorder 2 whose authentication key has been exchanged are not associated with each other due to the presence of the unauthorized device 4 or the like. It is assumed that the process has failed, and the decoding process is immediately stopped to notify the user. In this way, by re-executing the authentication key exchange process, the cause of failure of the content key confirmation process can be identified, and appropriate countermeasures corresponding to the identified cause of failure can be quickly implemented.
FIG. 5 is a flowchart showing an operation procedure related to the content key confirmation process of the digital TV apparatus 1.

  The digital TV apparatus 1 executes a content key confirmation process in parallel with the start of content reception (step A1). Then, it is checked whether or not the content key confirmation is successful (step A2). If it is not successful (NO in step A2), the authentication key exchange process is re-executed (step A3).

  If the authentication key obtained by re-execution of the authentication key exchange process has been updated (YES in step A4), it is determined that the cause of failure of the content key confirmation process is due to mismatch of authentication keys, and step The process restarts from the content key confirmation process of A1. On the other hand, if the authentication key has not been updated (NO in step A4), the failure cause of the content key confirmation process is that the received content and the HDD recorder 2 that has exchanged the authentication key are not associated with each other. It judges, stops a decoding process (step A5), outputs that fact, and notifies a user (step A6).

  Thus, it is possible to perform appropriate operation control according to the situation.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  In the first embodiment described above, the operation control method for quickly executing an appropriate measure corresponding to the cause of the failure when the content key confirmation process has failed has been described. However, in the second embodiment, the content control method is described. An operation control method for preventing the failure of the key confirmation process will be described. Again, the communication apparatus of the present invention is realized as the digital TV apparatus 1 shown in FIGS. 1 and 2.

  In general, devices that receive and play content, whether digital or analog, typically have a function to perform special playback called slow or fast-forward, for example, in addition to normal playback that plays back the received content at normal speed. It is. Each time the source device receives a content acquisition request (content reception request) from the sink device, it updates the content key added as a parameter to the content to be transmitted. During normal playback, the sink device acquires the content as a whole with a single content acquisition request, but during fast-forward playback, the sink device thins out the content and acquires multiple content acquisition requests (content partial acquisition requests). To do. That is, at the time of fast-forward playback, the content device is requested to receive the content more than a predetermined number of times within a certain time, and the content key is frequently updated on the source device side.

  Accordingly, at the time of special playback (fast forward), a failure of the content key confirmation process performed between the sink device and the source device may be caused. Therefore, in the digital TV apparatus 1 of the second embodiment, a special key is used. A mechanism is provided for preventing failure of the content key confirmation process during playback. Hereinafter, this mechanism will be described in detail.

  FIG. 6 is a timing chart showing the execution timing of the content key confirmation process (CKC) between the sink device and the source device.

  Now, it is assumed that the sink device is trying to acquire content data (1), (2), (3),... Followed by the content from the source device ((A) in FIG. 6). When the sink device performs normal playback, the content transfer between the source device and the sink device is performed over the whole with a single request ((B) in FIG. 6). At the time of this request, the source device updates the content key, and the sink device executes a content key confirmation process for this content key.

  On the other hand, when the sink device is performing special playback (fast forward), content transfer between the source device and the sink device is performed for each part by a plurality of requests ((C) in FIG. 6). Since the source device updates the content key for each request, there may be a case where the content device has already been updated in the source device when the sink device executes the content key confirmation process. In this case, the content key confirmation process fails.

  Therefore, in the digital TV device 1 of the second embodiment, the frequency of content acquisition requests that are the cause of content encryption / decryption parameter update is reduced until the content key confirmation is successful. The operation control such as stopping the content acquisition request is performed. This avoids a situation where the content key confirmation process fails and content decryption must be stopped even though the received content is associated with the device that has exchanged the authentication key during special playback. Is possible.

  FIG. 7 is a flowchart showing an operation procedure related to the first content key confirmation process at the time of special playback of the digital TV apparatus 1.

  When the digital TV device 1 makes a content acquisition request (step B1), it checks whether the content key has already been confirmed (step B2). If the content key has already been confirmed (YES in step B2), the digital TV apparatus 1 determines whether or not to continue the special reproduction (step B6), and if continued (YES in step B6), step B1. Repeat the process from. If the special reproduction is not continued (NO in step B6), the digital TV apparatus ends this process.

  On the other hand, if the content key confirmation has not been performed yet (NO in step B2), the digital TV apparatus 1 starts the content key confirmation process (step B3). Thereafter, the digital TV apparatus 1 determines whether or not the content key confirmation has been completed (step B4). If it has not been completed (NO in step B4), the digital TV device 1 has a certain amount of time sufficient for executing the content key confirmation process. Wait for a time (step B5). By providing the step of waiting for a certain period of time, the next content acquisition request is delayed, so that the failure of the content key confirmation process due to the content key update can be prevented.

  FIG. 8 is a flowchart showing an operation procedure related to the second content key confirmation process at the time of special playback of the digital TV apparatus 1. The difference from the operation procedure shown in FIG. 7 is that, instead of waiting for a certain time as in step B5 of FIG. 7, it is monitored whether or not the content key confirmation processing is finished and waits until the end. (Step C4). That is, the next content acquisition request is stopped. Thereby, the failure of the content key confirmation process caused by the content key update can be surely prevented.

  Thus, it is possible to perform appropriate operation control according to the situation.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The figure which shows the example of 1 usage pattern of the communication apparatus of 1st Embodiment of this invention The block diagram which shows schematic structure about the part regarding the content acquisition of the digital TV apparatus of the said 1st Embodiment. Timing chart showing communication procedure executed between sink device and source device in DTCP-IP The figure which shows the example in which an unauthorized device intervenes between a Sink device and a Source device. The flowchart which shows the operation | movement procedure in connection with the content key confirmation process of the digital TV apparatus of the said 1st Embodiment. Timing chart showing execution timing of content key confirmation processing between sink device and source device The flowchart which shows the operation | movement procedure in connection with the 1st content key confirmation process at the time of special reproduction of the digital TV apparatus of the said 2nd Embodiment. The flowchart which shows the operation | movement procedure in connection with the 2nd content key confirmation process at the time of special reproduction of the digital TV apparatus of the said 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Digital TV apparatus, 2 ... HDD recorder, 3 ... Router, 4 ... Unauthorized device, 11 ... User interface part, 12 ... DTCP-IP transfer part, 13 ... AKE part, 14 ... Operation part, 15 ... PCP part, 16 …socket.

Claims (7)

In a communication device that receives content having a content key from another communication device via an IP (Internet Protocol) network,
An authentication key exchanging means for acquiring an authentication key for identifying each other device with the other communication device and authenticating the other communication device;
A content key included in content received via the IP network is transmitted to the other communication device authenticated by the authentication key exchanging means, and the received content is transmitted as a response to the transmission from the other communication device. Content key confirmation means for confirming whether or not it is obtained from the other communication device authenticated by the exchange means;
As a result of confirmation by the content key confirmation unit, if the received content is not obtained from the other communication device authenticated by the authentication key exchange unit,
A first control for re-executing the authentication key exchanging means and determining whether the authentication key acquired by the re-execution and the authentication key before the re-execution are the same;
If it is determined by the first control that the authentication keys are not the same, the content key confirmation unit is re-executed, and the received content is obtained from the other communication device authenticated by the authentication key exchange unit A second control for determining whether or not;
Control means for executing third control for stopping reception of the content when it is determined that the content received by the second control is not acquired from the other communication device;
A communication apparatus comprising:   2. A notification unit that outputs that a communication device other than the other communication device authenticated by the authentication key exchanging unit may intervene when reception of the content is stopped. Communication equipment. In a communication device that receives content having a content key updated at a predetermined timing from another communication device via an IP (Internet Protocol) network,
An authentication key exchanging means for acquiring an authentication key for identifying each other device with the other communication device and authenticating the other communication device;
A content key included in content received via the IP network is transmitted to the other communication device authenticated by the authentication key exchanging means, and the received content is transmitted as a response to the transmission from the other communication device. Content key confirmation means for confirming whether or not it is obtained from the other communication device authenticated by the exchange means;
When a fast-forward playback request is made to request reception of the content more than a predetermined number of times within a predetermined time with respect to the other communication device authenticated by the authentication key exchange means, until confirmation by the content key confirmation means is completed Control means for reducing the frequency of the content reception request;
A communication apparatus comprising: In a communication device that receives content having a content key updated at a predetermined timing from another communication device via an IP (Internet Protocol) network,
An authentication key exchanging means for acquiring an authentication key for identifying each other device with the other communication device and authenticating the other communication device;
A content key included in content received via the IP network is transmitted to the other communication device authenticated by the authentication key exchanging means, and the received content is transmitted as a response to the transmission from the other communication device. Content key confirmation means for confirming whether or not it is obtained from the other communication device authenticated by the exchange means;
When a fast-forward playback request is made to request reception of the content more than a predetermined number of times within a predetermined time with respect to the other communication device authenticated by the authentication key exchange means, until confirmation by the content key confirmation means is completed Control means for stopping the content reception request;
A communication apparatus comprising:   5. The communication apparatus according to claim 1, 2, 3, or 4, wherein the communication apparatus conforms to DTCP (Digital Transmission Content Protection) -IP. In a digital television device that receives content having a content key from another communication device via an IP (Internet Protocol) network,
An authentication key exchanging means for acquiring an authentication key for identifying each other device with the other communication device and authenticating the other communication device;
A content key included in content received via the IP network is transmitted to the other communication device authenticated by the authentication key exchanging means, and the received content is transmitted as a response to the transmission from the other communication device. Content key confirmation means for confirming whether or not it is obtained from the other communication device authenticated by the exchange means;
As a result of confirmation by the content key confirmation unit, if the received content is not obtained from the other communication device authenticated by the authentication key exchange unit,
A first control for re-executing the authentication key exchanging means and determining whether the authentication key acquired by the re-execution and the authentication key before the re-execution are the same;
If it is determined by the first control that the authentication keys are not the same, the content key confirmation unit is re-executed, and the received content is obtained from the other communication device authenticated by the authentication key exchange unit A second control for determining whether or not;
Control means for executing third control for stopping reception of the content when it is determined that the content received by the second control is not acquired from the other communication device;
A digital television device comprising: A communication device control method for receiving content having a content key from another communication device via an IP (Internet Protocol) network,
An authentication key exchange step of acquiring an authentication key for identifying each other device with the other communication device and authenticating the other communication device;
A content key included in content received via the IP network is transmitted to the other communication device authenticated by the authentication key exchange step, and the received content is transmitted as a response to the transmission from the other communication device. A content key confirmation step for confirming whether or not it is obtained from the other communication device authenticated by the exchange step;
As a result of confirmation by the content key confirmation step, if the received content is not obtained from the other communication device authenticated by the authentication key exchange step,
A first control for re-executing the authentication key exchange step and determining whether or not the authentication key acquired by the re-execution and the authentication key before the re-execution are the same;
If it is determined by the first control that the authentication keys are not the same, the content key confirmation step is re-executed, and the received content is obtained from the other communication device authenticated by the authentication key exchange step A second control for determining whether or not;
A control step of executing third control for stopping reception of the content when it is determined that the content received by the second control is not obtained from the other communication device;
A control method for a communication apparatus, comprising:

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