JP2007104430A - Encrypted data transmitting apparatus, encryption key updating method, electronic device, program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a receiver can not rightly decrypt encrypted data if an encryption key is updated just after a transmitter transmits the encryption key to the receiver. <P>SOLUTION: An encryption key updating means 306 is provided, which judges whether next encrypted data are transmitted within a first predetermined time from the transmission completion of encrypted data and whether authentication and key exchange is performed after the lapse of a second predetermined time shorter than the first predetermined time, updates an encryption key in the end of the first predetermined time if the next encrypted data are not transmitted within the first predetermined time and the authentication and key exchange is not performed after the lapse of the second predetermined time, and updates the encryption key in the case of the authentication and key exchange if the next encrypted data are not transmitted within the first predetermined time and the authentication and key exchange is performed after the lapse of the second predetermined time. A counter 310 for the first and second predetermined times is then reset when completing the transmission of the encrypted data and before transmitting the updated encryption key if the authentication and key exchange is performed after the lapse of the second predetermined time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an encrypted data transmission device, an encryption key update method, and an electronic device used when performing encrypted data transmission.

  Conventionally, this type of encryption key update method includes updating the encryption key (Kx) defined in the DTCP standard (Digital Transmission Content Protection standard). there were.

  FIG. 5 shows a block diagram of the encrypted data transmission / reception system described in Patent Document 1.

  The encrypted data transmission device 400 is connected to the encrypted data reception device 401 via the Ethernet (registered trademark) 419. From the encrypted data receiving device 401, an authentication / key exchange request, an encryption key identifier request, and a content transmission request are transmitted to the request analysis control unit 416 via the interface unit 412 of the encrypted data transmitting device 400. The request analysis control unit 416 manages generation / update of the encryption key Kx415 used for encrypting content data, controls authentication and key exchange in response to a request from the encrypted data receiving device 401, and Similarly, the return of the encryption key identifier is controlled in response to the request from the encrypted data receiving apparatus 401.

  Hereinafter, an operation when the encrypted data transmitting apparatus 400 receives various requests from the encrypted data receiving apparatus 401 will be described.

  The encryption key generation unit 425 of the request analysis control unit 416 generates the encryption key Kx415, discards / updates the encryption key Kx415, and assigns the encryption key identifier 413 in synchronization with the discard / update. These encryption key Kx415 and encryption key identifier 413 are stored in the encryption key register 414.

  When the request analysis control unit 416 receives a request for content data from the encrypted data receiving device 401, the analysis unit 421 analyzes the request content and instructs the data transmission control unit 422 to control the encrypted data transmission. The data transmission control unit 422 issues a plaintext content data read request to the hard disk 410 in which the content data is stored, and simultaneously instructs the data encryption transmission unit 411 to perform encryption. Upon receiving the encryption instruction from the data transmission control unit 422, the data encryption transmission unit 411 encrypts the plaintext content data read from the hard disk 410 using the encryption key Kx415 read from the encryption key register 414. The encrypted content data is returned to the encrypted data receiving apparatus 401 via the interface unit 412.

  Further, when the request analysis control unit 416 receives an authentication / key exchange request from the encrypted data receiving apparatus 401, the analysis unit 421 analyzes the request content, and the authentication control unit 424 controls the authentication and key exchange. Instruct. The authentication control unit 424 instructs the authentication / key exchange unit 417 to perform authentication and key exchange with the encrypted data reception device 401, and the authentication / key exchange unit 417 transmits the encrypted data reception device 401. When the authentication is successful and the key exchange is successful, the encryption key Kx 415 and the encryption key identifier 413 read from the encryption key register 414 are transmitted to the encrypted data receiving apparatus 401 through the authentication control unit 424.

  When the request analysis control unit 416 requests the encryption key identifier 413 from the encrypted data receiving apparatus 401, the analysis unit 421 analyzes the request content and instructs the identifier transmission control unit 423 to control identifier transmission. The identifier transmission control unit 423 gives the encryption key identifier 413 read from the encryption key register 414 to the encryption key identifier request processing unit 418 and instructs the encrypted data receiving apparatus 401 to return it. Upon receiving this instruction, the encryption key identifier request processing unit 418 returns the encryption key identifier 413 to the encrypted data receiving apparatus 401 via the interface unit 412.

  Next, a method for updating the encryption key in the conventional encrypted data transmission apparatus 400 will be described with reference to FIGS.

  FIG. 6 shows a method of updating the encryption key in the conventional encrypted data transmission apparatus 400 shown in FIG. 5, and the encrypted data receiving apparatus converts the data encrypted by the encrypted data transmission apparatus 400 with the encryption key Kx. It is the figure which represented the procedure which 401 receives in time series.

  In FIG. 6, the encrypted data transmission device 400 generates a first encryption key Kx [1] at time 500. When the encrypted data receiving apparatus 401 requests authentication / key exchange from the encrypted data transmitting apparatus 400, the encrypted data transmitting apparatus 400 performs authentication / key exchange, and if the authentication is successful, The encryption key Kx [1] is transmitted to the encrypted data receiving apparatus 401 (501).

  Next, the encrypted data receiving apparatus 401 transmits a content data transmission request 502 to the encrypted data transmitting apparatus 400, and the encrypted data transmitting apparatus 400 that has received the request transmits the requested content to the encryption key Kx [ 1] and the encrypted data 503 is transmitted. The encrypted data receiving apparatus 401 repeats these content data requests as many times as necessary, such as the content requests 502 and 504, and the encrypted data transmitting apparatus 400 transmits the content data requested in response to these requests. Encryption is performed using the encryption key Kx [1], and the encrypted data 503 and 505 are transmitted.

  The data transmission control unit 422 of the request analysis control unit 416 causes the Kx update timer 420 to count the time from the completion of transmission of the encrypted data. When transmission of the encrypted data from the encrypted data transmitting apparatus 400 is completed and then a predetermined time (2 hours in this example) elapses without transmission of the encrypted data, the encryption of the request analysis control unit 416 The key generation unit 425 considers that a series of encrypted data transmission has been completed, discards / updates the encryption key Kx [1] that has been used to secure the encrypted data transmission, and renews it at time 506. The encryption key Kx [2] is generated.

  After time 506, the encryption key Kx [1] has already been discarded and becomes invalid, so that if the encrypted data receiving apparatus 401 wants to receive data from the encrypted data transmitting apparatus 400 again, a new authentication is performed. A new encryption key Kx [2] needs to be obtained again from the encrypted data transmission device 400 by requesting key exchange (507).

In the authentication / key exchange 507, the encrypted data receiving apparatus 401 that has acquired the new encryption key Kx [2] transmits the encrypted content data to the encrypted data transmitting apparatus 400 in the same manner as the content request 502 or 504. When the transmission request 508 is transmitted, the encrypted data transmitting apparatus 400 encrypts the requested content with the encryption key Kx [2] and transmits the encrypted data 509 to the encrypted data receiving apparatus 401 accordingly.
Japanese Patent Laid-Open No. 11-289326

  However, in the conventional encryption key update method, it is defined that the encryption key Kx is discarded / updated after a predetermined time (2 hours in the above example) after the last transmission of the encrypted data is completed. Therefore, if there is a request for authentication and key exchange from the encrypted data receiving device 401 at the timing immediately before the predetermined time has elapsed, the encrypted data receiving device 401 sends the encrypted data transmitted thereafter. There was a problem that the encrypted data could not be decrypted.

  Hereinafter, this problem will be described using the above-described conventional encryption key updating method as an example.

  In the case of this conventional encryption key update method, the destruction / update timing of the encryption key Kx is determined to be two hours after the last transmission of the encrypted data. The two-hour progress is not initialized until transmission is started.

  Here, consider a case where the authentication / key exchange 507 in FIG. 6 occurs immediately before the time 506 when the encryption key Kx is updated.

  FIG. 7 shows an encryption key update method in the conventional encrypted data transmission apparatus 400 shown in FIG. 5 when authentication and key exchange occur immediately before the time 506 when the encryption key Kx is updated. The same reference numerals are used for parts having the same timing as in FIG. The timing of authentication / key exchange 510 is different from the timing of authentication / key exchange 507 in FIG.

  In the case of FIG. 7, at time 506 immediately after the encrypted data receiving apparatus 401 receives the encryption key Kx [1] in the authentication / key exchange 510, an encryption key update event occurs in the encrypted data transmitting apparatus 400. When the encrypted data transmitting apparatus 400 receives the content transmission request 511 from the encrypted data receiving apparatus 401 after the encryption key is updated at time 506, the encrypted data transmitting apparatus 400 is updated. The content is encrypted with the encryption key Kx [2], and the encrypted data 512 is transmitted.

  That is, in this case, the encrypted data receiving device 401 encrypts the content data with the encryption key Kx [2] different from the encryption key Kx [1] received from the encrypted data transmitting device 400. The encrypted data receiving apparatus 401 cannot correctly decrypt the encrypted data 512 received in response to the content request 511.

  In the configuration of the conventional encrypted transmission / reception system, the encrypted data receiving apparatus 401 can request the encrypted data transmitting apparatus 400 to refer to the unique identifier given to the encryption key. This identifier reference request is used for the encrypted data receiving apparatus 401 to know whether or not the encryption key Kx has been updated on the encrypted data transmitting apparatus 400 side without performing the authentication / key exchange process. It is done.

  That is, when it becomes necessary for the encrypted data receiving apparatus 401 to receive content from the encrypted data transmitting apparatus 400, the encrypted data receiving apparatus 401 needs to perform the authentication / key exchange process and acquire the encryption key Kx again. In order to know whether the encryption key Kx previously obtained from the encrypted data transmission device 400 is still valid and the authentication / key exchange process does not have to be performed again. On the other hand, reference to the identifier of the encryption key Kx is requested.

  As a result of acquiring the identifier of the encryption key Kx, the encrypted data receiving device 401 determines that the encryption key Kx acquired from the encrypted data transmitting device 400 in the previous authentication / key exchange process is still valid. The content data request is transmitted to the encrypted data transmitting apparatus 400 without performing the authentication / key exchange process again. Conversely, if it is found that the previously acquired encryption key Kx has already been destroyed / updated, the authentication / key exchange process is performed prior to the content data request to acquire the updated encryption key Kx. After that, the content data transmission request is transmitted to the encrypted data transmission apparatus 400.

  Here, immediately after the encrypted data receiving apparatus 401 obtains the identifier of the encryption key Kx, a case where the encryption key update event occurs at the time 506 shown in FIG.

  It is assumed that the response obtained as a result of requesting the encrypted data transmitting device 400 for the encryption key identifier indicates that the encryption key Kx held by the encrypted data receiving device 401 has not been updated. Next, it is assumed that an encryption key update event occurs in the encrypted data transmission device 400 at a timing immediately after the result of this identifier request is returned to the encrypted data reception device 401. In this case, based on the assumption that the encryption key Kx has not been updated, the encrypted data receiving apparatus 401 makes a content data transmission request to the encrypted data transmitting apparatus 400. In the encrypted data transmitting apparatus 400, The new encryption key after the update is used as the encryption key for performing the encryption upon receiving the content data transmission request from the encrypted data receiving device 401, and this encrypted data is received. This means that the encrypted data receiving apparatus 401 cannot correctly decrypt the received encrypted data.

  The present invention solves the above-described conventional problems, and an object thereof is to provide an encrypted data transmission device, an encryption key update method, and an electronic device that can reliably receive received encrypted data. And

In order to solve the above-described problem, the first aspect of the present invention provides:
Encryption key storage means for storing an encryption key for encrypting content data to be transmitted;
Encrypted data transmission means for encrypting the content data using the encryption key and transmitting the encrypted data;
An authentication / key exchange means for performing authentication and key exchange with the encrypted data receiving device;
Whether or not the next encrypted data has been transmitted within the first predetermined time since the transmission of the encrypted data has been completed, and the first shorter than the first predetermined time since the completion of the transmission of the encrypted data. 2 after the elapse of a predetermined time of 2 and whether or not authentication and key exchange have been performed within the first predetermined time, and the next encrypted data is not transmitted within the first predetermined time. If the authentication and key exchange are not performed within the first predetermined time after the second predetermined time has elapsed, the encryption key is updated at the end of the first predetermined time. When the next encrypted data is not transmitted within the first predetermined time, and after the second predetermined time has elapsed, the authentication and key exchange are performed within the first predetermined time. Includes the encryption key during the authentication and key exchange. To update, and an encryption key update means,
The counters for the first predetermined time and the second predetermined time are a timing when transmission of encrypted data is completed, and after the second predetermined time has elapsed and within the first predetermined time. The encrypted data transmission device is reset to the timing before transmitting the updated encryption key at the time of the authentication and key exchange when the authentication and key exchange are performed.

The second aspect of the present invention
An encryption key storage means for storing an encryption key for encrypting content data to be transmitted, and an identifier of the encryption key;
Encrypted data transmission means for encrypting the content data using the encryption key and transmitting the encrypted data;
An authentication / key exchange means for performing authentication and key exchange with the encrypted data receiving device;
Identifier transmitting means for transmitting the identifier to the encrypted data receiving device;
Whether or not the next encrypted data has been transmitted within the first predetermined time since the transmission of the encrypted data has been completed, and the first shorter than the first predetermined time since the completion of the transmission of the encrypted data. 2 after the elapse of a predetermined time of 2, and whether or not the identifier is transmitted within the first predetermined time, and the next encrypted data is not transmitted within the first predetermined time. When the identifier is not transmitted within the first predetermined time after the elapse of the predetermined time of 2, the encryption key and the identifier are updated at the end of the first predetermined time, and the first If the next encrypted data is not transmitted within a predetermined time of 1 and the identifier is transmitted within the first predetermined time after the second predetermined time has elapsed, the identifier is When sending the encryption key and To update the serial identifier, and an encryption key update means,
The counters for the first predetermined time and the second predetermined time are a timing when transmission of encrypted data is completed, and after the second predetermined time has elapsed and within the first predetermined time. When the identifier is transmitted to the encrypted data transmission device, the encrypted data transmission device is reset to a timing before transmitting the updated identifier.

The third aspect of the present invention
An encrypted data transmission step of encrypting content data using an encryption key and transmitting the encrypted data;
An authentication / key exchange step for performing authentication and key exchange with the encrypted data receiving device;
Whether or not the next encrypted data has been transmitted within the first predetermined time since the transmission of the encrypted data has been completed, and the first shorter than the first predetermined time since the completion of the transmission of the encrypted data. 2 after the elapse of a predetermined time of 2 and whether or not authentication and key exchange have been performed within the first predetermined time, and the next encrypted data is not transmitted within the first predetermined time. If the authentication and key exchange are not performed within the first predetermined time after the second predetermined time has elapsed, the encryption key is updated at the end of the first predetermined time. When the next encrypted data is not transmitted within the first predetermined time, and after the second predetermined time has elapsed, the authentication and key exchange are performed within the first predetermined time. Includes the encryption key during the authentication and key exchange. To update, and the encryption key update step,
The timing when transmission of encrypted data is completed, and the authentication and key exchange when the authentication and key exchange are performed within the first predetermined time after the second predetermined time has elapsed. A counter reset step of resetting the counters of the first predetermined time and the second predetermined time at a timing before transmitting the updated encryption key at the time of the encryption key update method, is there.

The fourth aspect of the present invention is
An encrypted data transmission step of encrypting content data using an encryption key and transmitting the encrypted data;
An authentication / key exchange step for performing authentication and key exchange with the encrypted data receiving device;
An identifier transmission step of transmitting the encryption key identifier to the encrypted data receiving device;
Whether or not the next encrypted data has been transmitted within the first predetermined time since the transmission of the encrypted data has been completed, and the first shorter than the first predetermined time since the completion of the transmission of the encrypted data. 2 after the elapse of a predetermined time of 2, and whether or not the identifier is transmitted within the first predetermined time, and the next encrypted data is not transmitted within the first predetermined time. If the identifier is not transmitted within the first predetermined time after the elapse of the predetermined time of 2, the encryption key is updated at the end of the first predetermined time, and the first predetermined time is updated. When the identifier is transmitted within the first predetermined time after the second predetermined time elapses when the next encrypted data is not transmitted within the time, when transmitting the identifier Updating the encryption key and the identifier Carried out, and the encryption key update step,
The timing when the transmission of encrypted data is completed, and the updated identifier when the identifier is transmitted within the first predetermined time after the second predetermined time has elapsed And a counter reset step for resetting the counters of the first predetermined time and the second predetermined time at a timing before the encryption key update method.

The fifth aspect of the present invention provides
It is an electronic device provided with the encrypted data transmission device of the first or second aspect of the present invention.

The sixth aspect of the present invention provides
In the encryption key update method of the third aspect of the present invention, the encrypted data transmission step of encrypting and transmitting content data, the authentication / key exchange step of performing authentication and key exchange, and the encryption of updating the encryption key A program for causing a computer to execute a key update step and the counter reset step of resetting a counter of the first predetermined time and the second predetermined time.

The seventh aspect of the present invention
In the encryption key update method of the fourth aspect of the present invention, the encrypted data transmission step of encrypting and transmitting content data, the authentication / key exchange step of performing authentication and key exchange, the identifier transmission step of transmitting an identifier, A program for causing a computer to execute the encryption key update step for updating the encryption key and the counter reset step for resetting a counter for the first predetermined time and the second predetermined time.

In addition, the eighth aspect of the present invention
A recording medium on which the program of the sixth or seventh aspect of the present invention is recorded, and is a recording medium that can be processed by a computer.

  According to the present invention, it is possible to provide an encrypted data transmission device, an encryption key update method, and an electronic device that can reliably decrypt the received encrypted data.

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

(Embodiment 1)
FIG. 1 shows a block diagram of an encrypted data transmission / reception system according to a first embodiment for realizing the encryption key update method of the present invention.

  The encrypted data transmission device 110 is connected to the encrypted data reception device 111 via the Ethernet 309. From the encrypted data receiving device 111, an authentication / key exchange request, an encryption key identifier request, and a content transmission request are transmitted to the request analysis control unit 306 via the interface unit 302 of the encrypted data transmitting device 110. The request analysis control unit 306 manages generation / update of the encryption key Kx305 used for encrypting the content data, controls authentication / key exchange in response to a request from the encrypted data receiving apparatus 111, and Similarly, the return of the encryption key identifier 303 is controlled in response to the request from the encrypted data receiving apparatus 111.

  Hereinafter, the configuration of the encrypted data transmission apparatus 110 will be described together with the operation when the request analysis control unit 306 receives various requests from the encrypted data reception apparatus 111.

  The encryption key generation unit 315 of the request analysis control unit 306 generates the encryption key Kx305, discards / updates the encryption key Kx305 according to conditions described later, and assigns the encryption key identifier 303 in synchronization with the discard / update. These encryption key Kx 305 and encryption key identifier 303 are stored in the encryption key register 304. The encryption key generation unit 315 corresponds to an example of the encryption key update unit of the present invention, and the encryption key register 304 corresponds to an example of the encryption key storage unit of the present invention.

  When the request analysis control unit 306 receives a request for content data from the encrypted data receiving apparatus 111, the analysis unit 311 analyzes the request content and instructs the data transmission control unit 312 to control encrypted data transmission. The data transmission control unit 312 issues a plaintext content data read request to the hard disk 300 in which the content data is stored, and simultaneously instructs the data encryption transmission unit 301 to perform encryption.

  In response to the encryption instruction from the data transmission control unit 312, the data encryption transmission unit 301 encrypts the plaintext content data read from the hard disk 300 using the encryption key Kx 305 read from the encryption key register 304. The encrypted content data is returned to the encrypted data receiving apparatus 111 via the interface unit 302. The data encryption transmission unit 301 corresponds to an example of the encrypted data transmission unit of the present invention.

  Further, when the request analysis control unit 306 receives an authentication / key exchange request from the encrypted data receiving apparatus 111, the analysis unit 311 analyzes the request content, and the authentication control unit 314 controls authentication and key exchange. Instruct.

  The authentication control unit 314 instructs the authentication / key exchange unit 307 to perform authentication / key exchange with the encrypted data reception device 111, and the authentication / key exchange unit 307 performs the encryption / data exchange device 111. If the authentication / key exchange is successful, the encryption key Kx 305 and the encryption key identifier 303 read from the encryption key register 304 are transmitted to the encrypted data receiving apparatus 111 through the authentication control unit 314. The authentication / key exchange unit 307 corresponds to an example of the authentication / key exchange unit of the present invention.

  When the request analysis control unit 306 is requested by the encrypted data receiving apparatus 111 to transmit an encryption key identifier, the analysis unit 311 analyzes the request content and instructs the identifier transmission control unit 313 to control identifier transmission. .

  The identifier transmission control unit 313 gives the encryption key identifier 303 read from the encryption key register 304 to the encryption key identifier request processing unit 308 and instructs the encrypted data reception device 111 to return it. Upon receiving this instruction, the encryption key identifier request processing unit 308 returns the encryption key identifier 303 to the encrypted data receiving apparatus 111 via the interface unit 302. The encryption key identifier request processing unit 308 corresponds to an example of an identifier transmission unit according to the present invention.

  The data transmission control unit 312, the identifier transmission control unit 313, and the authentication control unit 314 each start counting of the Kx update timer 310, and the encryption key generation unit 315, the identifier transmission control unit 313, and the authentication control unit 314 respectively update the Kx According to the count value of the timer 310, the encryption key Kx305 and the encryption key identifier 303 are updated. The timing for starting the count of the Kx update timer 310 and the timing for updating the encryption key Kx 305 and the encryption key identifier 303 will be described later. The Kx update timer 310 corresponds to an example of a counter for the first predetermined time and the second predetermined time of the present invention.

  Next, a method for updating the encryption key in encrypted data transmission apparatus 110 according to the first embodiment will be described with reference to FIGS.

  FIG. 2 shows a method of updating the encryption key in the encrypted data transmission apparatus 110 of the first embodiment shown in FIG. 1, and the data encrypted by the encrypted data transmission apparatus 110 with the encryption key Kx is encrypted. It is the figure which represented the procedure which the digitization data receiver 111 receives in time series. 2 shows the same timing as that shown in FIG. 7 in which the encrypted data received by the encrypted data receiving apparatus 401 shown in FIG. 5 could not be correctly decrypted in the above-described conventional encrypted data transmission / reception system. Is. That is, the timing when an authentication / key exchange request is received from the encrypted data receiving apparatus 111 immediately before a predetermined time (2 hours) elapses from the time when transmission of the last encrypted data is completed is shown. Yes.

  In FIG. 2, the encrypted data transmission device 110 generates a first encryption key Kx [1] at time 100. When the encrypted data receiving apparatus 111 requests authentication / key exchange from the encrypted data transmitting apparatus 110, the encrypted data transmitting apparatus 110 performs authentication / key exchange, and encrypts if the authentication is successful. The encryption key Kx [1] is transmitted to the data receiving apparatus 111 (101).

  Next, the encrypted data receiving apparatus 111 transmits a content data transmission request 102 to the encrypted data transmitting apparatus 110, and the encrypted data transmitting apparatus 110 that has received the request transmits the requested content data to the encryption key Kx. The data is encrypted with [1] and the encrypted data 103 is transmitted. The encrypted data receiving apparatus 111 repeats these content data requests as many times as necessary, such as the content requests 102 and 104, and the encrypted data transmitting apparatus 110 transmits the content data requested in response to these requests. Encryption is performed using the encryption key Kx [1], and the encrypted data 103 and 105 are transmitted.

  The data transmission control unit 312 of the request analysis control unit 306 causes the Kx update timer 310 to count the time from the completion of transmission of the encrypted data. When transmission of the encrypted data from the encrypted data transmitting apparatus 110 is completed and then a predetermined time (2 hours in this example) has passed without transmission of the encrypted data, the request analysis control unit The encryption key generation unit 315 of 306 considers that a series of encrypted data transmission has been completed, and discards / updates the encryption key Kx [1] that has been used so far for securing the encrypted data transmission. In 106, a new encryption key Kx [2] is generated.

  When the encrypted data receiving apparatus 111 wants to receive data from the encrypted data transmitting apparatus 110 again, a new authentication / key exchange request is made. Here, this request is issued immediately before time 106.

  Here, the authentication control unit 314 that has received a new authentication / key exchange request from the encrypted data receiving apparatus 111 refers to the count value of the Kx update timer 310 and completes the transmission of the last encrypted data. It is determined whether or not it is a time of 5 minutes immediately before a predetermined time (2 hours) elapses, that is, whether or not 1 hour and 55 minutes have elapsed since the last transmission of encrypted data was completed.

  Note that the predetermined time (2 hours) set to perform the destruction / update of the encryption key when the encrypted data has not been transmitted is an example of the first predetermined time of the present invention. The time set as 1 hour and 55 minutes from the time when the transmission of the last encrypted data, which is shorter than the first predetermined time, is an example of the second predetermined time of the present invention.

  If it is before 1 hour and 55 minutes have passed since the last transmission of encrypted data, the authentication control unit 314 does not update the encryption key, and the encryption key Kx305 stored in the encryption key register 304 is not updated. The authentication / key exchange unit 307 is instructed to transmit the encryption key identifier 303 to the encrypted data receiving apparatus 111 during authentication and key exchange.

  On the other hand, if 1 hour 55 minutes or more have elapsed since the last transmission of encrypted data, the authentication control unit 314 causes the encryption key generation unit 315 to update the encryption key Kx305, The authentication / key exchange unit 307 performs authentication and key exchange, and instructs the new encryption key Kx305 to be transmitted. In this case, the authentication control unit 314 counts the Kx update timer 310 after the encryption key generation unit 315 updates the encryption key Kx305 and before the authentication / key exchange unit 307 performs authentication and key exchange. Is reset and starts counting again.

  In the case of FIG. 2, the authentication / key exchange request from the encrypted data receiving apparatus 111 has been received after 1 hour and 55 minutes have elapsed since the last encrypted data transmission was completed. At the time 120 when the request is received, the control unit 314 discards / updates the encryption key Kx [1] used so far, generates a new encryption key Kx [2], and stores it in the encryption key register 304. The encryption key Kx 305 and the encryption key identifier 303 are rewritten. Then, the authentication control unit 314 passes the new encryption key Kx [2] to the authentication / key exchange unit 307, and transmits the new encryption key Kx [2] to the encrypted data receiving apparatus 111 through the authentication / key exchange 107. Let

  Immediately after the authentication / key exchange 107, the time 106, which is two hours after the completion of transmission of the last encrypted data, is reached, but the authentication control unit 314 performs the Kx update timer 310 during the authentication / key exchange 107. Therefore, at this time 106, two hours have not passed since the transmission of the last encrypted data was completed, and therefore the encryption key Kx is discarded / updated. I can't.

  Following the authentication / key exchange 107, a content transmission request 108 is issued from the encrypted data receiving apparatus 111 after the time 106. At this time, the encrypted data transmission apparatus 110 encrypts the content with the encryption key Kx [2] updated at time 120 and transmits the encrypted data 109.

  On the other hand, the encrypted data receiving apparatus 111 decrypts the received encrypted data 109 using the encryption key Kx [2] acquired at the time of the authentication / key exchange 107, so that it can be correctly decrypted.

  Next, the operation when the encrypted data receiving apparatus 111 refers to the unique identifier assigned to the encryption key will be described with reference to FIGS.

  FIG. 3 shows an encryption key update method in the encrypted data transmitting apparatus 110 of the first embodiment when the encrypted data receiving apparatus 111 refers to the identifier of the encryption key. FIG. 3 shows the timing when there is an identifier transmission request from the encrypted data transmitting apparatus 110 immediately before a predetermined time (2 hours) has elapsed since the completion of the transmission of the last encrypted data. . In FIG. 3, the same reference numerals as in FIG. 2 are used for portions corresponding to those in FIG.

  When referring to the identifier of the encryption key, the encrypted data receiving apparatus 111 issues an identifier reference request to the encrypted data transmitting apparatus 110 when it becomes necessary to receive content from the encrypted data transmitting apparatus 110. Then, in accordance with the identifier returned from the encrypted data transmitting apparatus 110, it is determined whether or not it is necessary to perform authentication / key exchange. That is, the identifier returned from the encrypted data transmitting apparatus 110 is compared with the identifier previously acquired from the encrypted data transmitting apparatus 110, and whether the previously acquired encryption key Kx is still valid is updated. Judge whether or not. If the previously acquired encryption key Kx is still valid, a request for content is sent to the encrypted data transmission device 110 without performing authentication and key exchange, and the encryption key Kx is updated. Then, after performing authentication and key exchange to obtain a new encryption key Kx, a content request is issued.

  Therefore, in FIG. 3, the encrypted data receiving apparatus 111 first transmits an identifier reference request 121 to the encrypted data transmitting apparatus 110 when issuing the content request 102.

  When the request analysis control unit 306 receives an identifier reference request from the encrypted data receiving device 111, the analysis unit 311 analyzes the request content and instructs the identifier transmission control unit 313 to control identifier transmission. Then, according to an instruction from the identifier transmission control unit 313, the encryption key identifier 303 stored in the encryption key register 304 is transmitted to the encrypted data reception device 111 by the encryption key identifier request processing unit 308.

  Since the encryption key is updated at the time 100 immediately before the identifier reference request 121, the encrypted data receiving device 111 determines that the encrypted data receiving device 111 has previously received the identifier received from the identifier reference request 121 in response to the identifier reference request 121. It is determined that the acquired encryption key Kx has been updated. Since the encryption key Kx acquired last time has been updated, the encrypted data receiving apparatus 111 next requests the encrypted data transmitting apparatus 110 for authentication and key exchange.

  Then, by the authentication / key exchange 101, the encrypted data receiving apparatus 111 acquires the encryption key Kx [1], and the encrypted data 103 and 105 received by the subsequent content requests 102 and 104 are converted into the received encryption key Kx. Decrypt with [1].

  In FIG. 3, the encrypted data receiving apparatus 111 issues an identifier reference request 122 to the encrypted data transmitting apparatus 110 immediately before time 106.

  Here, the identifier transmission control unit 313 that has received a new identifier reference request from the encrypted data receiving apparatus 111 refers to the count value of the Kx update timer 310 and completes the transmission of the last encrypted data. It is determined whether it is a time of 5 minutes immediately before a predetermined time (2 hours) has passed, that is, whether or not 1 hour and 55 minutes have passed since the last encrypted data transmission was completed.

  In FIG. 3, as in FIG. 2, the predetermined time (2 hours) set for destroying / updating the encryption key when the encrypted data has not been transmitted is the same as this time. This corresponds to an example of the first predetermined time of the invention. The time set as 1 hour and 55 minutes from the time when the transmission of the last encrypted data, which is shorter than the first predetermined time, is an example of the second predetermined time of the present invention.

  If it is before 1 hour and 55 minutes have elapsed since the last transmission of encrypted data, the identifier transmission control unit 313 does not update the encryption key, and the encryption key stored in the encryption key register 304 is not updated. It instructs the encryption key identifier request processing unit 308 to return the identifier 303 to the encrypted data receiving apparatus 111.

  On the other hand, if one hour and 55 minutes have passed since the last transmission of the encrypted data has been completed, the identifier transmission control unit 313 updates the encryption key Kx305 and the encryption key identifier 303 to the encryption key generation unit 315. After that, the encryption key identifier request processing unit 308 is instructed to send back the updated new encryption key identifier 303. In this case, the identifier transmission control unit 313 causes the encryption key identifier request processing unit 308 to return the encryption key identifier 303 after the encryption key generation unit 315 has updated the encryption key Kx305 and the encryption key identifier 303. Then, the count of the Kx update timer 310 is reset and starts counting again.

  In the case of FIG. 3, since the identifier reference request from the encrypted data receiving apparatus 111 has been received after 1 hour and 55 minutes have passed since the last encrypted data transmission was completed, identifier transmission control is performed. The unit 313 discards / updates the encryption key Kx [1] that has been used at the time 126 when the request is received, generates a new encryption key Kx [2], and is stored in the encryption key register 304. The existing encryption key Kx305 and encryption key identifier 303 are rewritten. Then, the identifier transmission control unit 313 passes the identifier of the new encryption key Kx [2] to the encryption key identifier request processing unit 308, and the encryption key identifier request processing unit 308 uses the identifier of the new encryption key Kx [2]. The data is transmitted to the encrypted data receiving apparatus 111.

  Immediately after the identifier reference request 122, the time 106, which is two hours after the completion of transmission of the last encrypted data, is reached, but the identifier transmission control unit 313 receives the identifier reference request 122 and receives the encryption key generation unit 315. Since the count of the Kx update timer 310 is reset when the encryption key Kx305 and the encryption key identifier 303 are updated, two hours have passed since the last transmission of the encrypted data was completed. Therefore, at the time 106, the process of discarding / updating the encryption key Kx is not performed.

  Following the transmission of the identifier reference request 122 and the identifier of the encryption key Kx [2], an authentication / key exchange request is issued from the encrypted data receiving apparatus 111 after the time 106, and the authentication / key exchange is performed ( 123). In the authentication / key exchange 123, the encrypted data receiving apparatus 111 acquires a new encryption key Kx [2].

  Further, following the authentication / key exchange 123, a content transmission request 124 is issued from the encrypted data receiving apparatus 111. At this time, the encrypted data transmission apparatus 110 encrypts the content with the encryption key Kx [2] updated at time 126 and transmits the encrypted data 125.

  On the other hand, the encrypted data receiving apparatus 111 decrypts the received encrypted data 125 using the encryption key Kx [2] acquired at the time of the authentication / key exchange 123, so that it can be correctly decrypted.

  Next, when the encrypted data receiving apparatus 111 shown in FIG. 3 refers to the unique identifier assigned to the encryption key, the encrypted data transmitting apparatus 110 updates the encryption key Kx305 and the encryption key identifier 303. The algorithm will be described with reference to FIGS.

  FIG. 4 shows a processing flow when the request analysis control unit 306 of the encrypted data transmission apparatus 110 updates the encryption key Kx 305 and the encryption key identifier 303.

  The encryption key generation unit 315 of the request analysis control unit 306 generates an initial value of the encryption key Kx305 and an encryption key identifier 303 corresponding to the initial value with a random number at initialization, and stores them in the encryption key register 304 (S200). ). At this time, the encryption key generation unit 315 starts counting of the Kx update timer 310 (S201), and the analysis unit 311 enters a state waiting for a request from the encrypted data receiving apparatus 111 (S202).

  The analysis unit 311 that has received some request from the encrypted data receiving apparatus 111 notifies the encryption key generation unit 315, and the encryption key generation unit 315 that has received the notification causes the count value of the Kx update timer 310 to exceed 2 hours. It is determined whether or not (S203). If the count value exceeds 2 hours, the encryption key generation unit 315 generates a new encryption key Kx305 value with a random number and reads the value of the encryption key identifier 303 from the encryption key register 304. Increment, write back to the encryption key register 304 again (S204), reset the count value of the Kx update timer 310, and start again from zero (S205).

  Next, the analysis unit 311 analyzes the request content from the encrypted data receiving apparatus 111 (S206), and branches the processing to S210, S207, and S214 according to the received request content.

  When the request received from the encrypted data receiving apparatus 111 is an authentication / key exchange request, the analysis unit 311 instructs the authentication control unit 314 to execute the authentication / key exchange request.

  The authentication control unit 314 determines whether or not the count value of the Kx update timer 310 exceeds 5 minutes before the time (2 hours) when the value of the encryption key Kx305 is updated in S204, that is, 1 hour and 55 minutes. If it exceeds (S210), it instructs the encryption key generation unit 315 to update the encryption key Kx305. Upon receiving the instruction, the encryption key generation unit 315 generates a new encryption key Kx305 value with a random number, reads the encryption key identifier 303 from the encryption key register 304, increments it, and writes it back to the encryption key register 304 again ( (S211), the count value of the Kx update timer 310 is reset and restarted from zero (S212).

  The authentication control unit 314 causes the authentication / key exchange unit 307 to perform authentication / key exchange with the encrypted data receiving apparatus 111 after the encryption key generation unit 315 updates the encryption key Kx305. Instruct. When the authentication / key exchange is completed, the authentication control unit 314 reads the encryption key Kx 305 and the encryption key identifier 303 from the encryption key register 304 and passes them to the authentication / key exchange unit 307, and the authentication / key exchange unit In step S213, the encrypted data reception apparatus 111 is transmitted.

  On the other hand, in S206, when the request received from the encrypted data receiving apparatus 111 is an encryption key identifier reference request, the analysis unit 311 instructs the identifier transmission control unit 313 to perform transmission of the identifier. put out.

  The identifier transmission control unit 313 determines whether or not the count value of the Kx update timer 310 exceeds the time point 5 minutes before the time (2 hours) when the value of the encryption key Kx305 is updated in S204, that is, 1 hour and 55 minutes. Judgment is made (S214), and if it exceeds, an instruction is issued to the encryption key generation unit 315 to update the encryption key Kx305. Upon receiving the instruction, the encryption key generation unit 315 generates a new encryption key Kx305 value with a random number, reads the encryption key identifier 303 from the encryption key register 304, increments it, and writes it back to the encryption key register 304 again ( In step S215, the count value of the Kx update timer 310 is reset and restarted from zero (S216).

  The identifier transmission control unit 313 updates the encryption key generation unit 315 with the encryption key Kx305, and then gives the encryption key identifier 303 to the encryption key identifier request processing unit 308, which is sent to the encrypted data reception device 111. To send it. Upon receiving this instruction, the encryption key identifier request processing unit 308 returns the requested encryption key identifier 303 to the encrypted data receiving apparatus 111.

  On the other hand, if the request received from the encrypted data receiving apparatus 111 is a content transmission request in S206, the analysis unit 311 instructs the data transmission control unit 312 to transmit the encrypted content data. put out.

  The data transmission control unit 312 gives an instruction to read the plaintext content data to the hard disk 300 and gives an instruction to encrypt the plaintext content data to the data encryption transmission unit 301. In response to this instruction, the data encryption transmission unit 301 reads the encryption key Kx 305 stored in the encryption key register 304, encrypts the plaintext content data using the encryption key Kx305 (S207), and transmits the encrypted content data to the interface. The encrypted data receiving apparatus 111 is returned via the unit 302 (S208). Further, the data transmission control unit 312 resets the count value of the Kx update timer 310 after completion of transmission of the encrypted data, and starts again from zero (S209).

  The processing of S213 and S217 corresponds to an example of the authentication / key exchange step and the identifier transmission step of the present invention, respectively. Further, the process combining S207 and S208 corresponds to an example of the encrypted data transmission step of the present invention. Also, the processes of S204, S211, and S217 are all examples of the encryption key update step of the present invention.

  Further, the case where the encryption key Kx305 is not updated in S211 and S215 but the encryption key Kx305 is updated in S204 is the second case where the next encrypted data is not transmitted within the first predetermined time of the present invention. This is an example in which authentication and key exchange are not performed within a first predetermined time after a predetermined time has elapsed. The case where the encryption key Kx305 is updated in S211 before the encryption key Kx305 is updated in S204 is the second case where the next encrypted data is not transmitted within the first predetermined time of the present invention. This is an example in which authentication and key exchange are performed within a first predetermined time after a predetermined time elapses. Further, the case where the encryption key Kx305 is updated in S215 before the encryption key Kx305 is updated in S204 is the second case where the next encrypted data is not transmitted within the first predetermined time of the present invention. This is an example of the case where the identifier is transmitted within the first predetermined time after the predetermined time elapses.

  The request analysis control unit 306 updates the encryption key Kx 305 and the encryption key identifier 303 in S211 or S215 in accordance with the algorithm described above, so that the encrypted data transmission apparatus 110 performs an authentication / key exchange request or an encryption key identifier information request. When the count value of the Kx update timer 310 exceeds 1 hour and 55 minutes at the time of receiving the password, the respective requests are executed after the encryption key Kx 305 and the encryption key identifier 303 are updated. As a result, the encryption key Kx305 is updated immediately after the encrypted data receiving apparatus 111 acquires the encryption key Kx305 by authentication / key exchange, or the encrypted data receiving apparatus 111 also acquires the encryption key identifier 303. Since there is no possibility that the encryption key Kx305 is updated immediately thereafter, it is possible to provide an encrypted data transmitting device and an encryption key updating method capable of reliably decrypting the encrypted content data received by the encrypted data receiving device 111. It becomes possible.

  Further, by providing the encrypted data transmitting apparatus 110 of the first embodiment in an electronic device that transmits encrypted data, an electronic device that can reliably decrypt the received encrypted content data can be provided. For example, the present invention can be applied to electronic devices that transmit encrypted content data such as AV devices, personal computers, and STBs connected via LAN.

  In the first embodiment, the time for updating the encryption key Kx is set to 2 hours and 1 hour 55 minutes after the last transmission of the encrypted data is completed. Even if the predetermined time is any value other than the predetermined time, the same effect can be obtained if the time updated in S211 and S215 in FIG. 4 is earlier than the time updated in S204. Needless to say.

  In the first embodiment, the plaintext content data is encrypted with the encryption key Kx. However, the content data is not directly encrypted with the encryption key Kx, but the content key is indirectly derived from the encryption key Kx. It goes without saying that the same effect can be obtained even if the data is encrypted.

  In the first embodiment, the configuration in which only one encrypted data receiving apparatus 111 is connected to the encrypted data transmitting apparatus 110 has been described. However, a plurality of encrypted data receiving apparatuses have one encryption. The encrypted data transmission device may be connected to receive the encrypted content data.

  In the first embodiment, the encrypted data transmitting apparatus 110 and the encrypted data receiving apparatus 111 are connected via the Ethernet 309. However, any connection method that can transmit and receive encrypted data is wired or wireless. It may be connected in any way.

  The program of the present invention includes the encrypted data transmission step of encrypting and transmitting content data, the authentication / key exchange step of performing authentication and key exchange, and the encryption of the encryption key update method of the present invention described above. For causing the computer to execute all or some of the operations of the encryption key updating step for updating the key, and the counter reset step for resetting the counter for the first predetermined time and the second predetermined time. A program that operates in cooperation with a computer.

  Further, the recording medium of the present invention includes the encrypted data transmission step of encrypting and transmitting content data of the encryption key update method of the present invention described above, the authentication / key exchange step of performing authentication and key exchange, All or some of the operations of all or some of the steps of the encryption key update step of updating the encryption key, the counter reset step of resetting the counter of the first predetermined time and the second predetermined time. It is a recording medium that records a program to be executed by a computer, and is a recording medium that can be read by the computer and that is used in cooperation with the computer.

  Further, the program of the present invention includes the encrypted data transmission step of encrypting and transmitting content data, the authentication / key exchange step of performing authentication and key exchange, and the identifier of the encryption key update method of the present invention described above. All or part of the identifier transmitting step for transmitting the encryption key, the encryption key updating step for updating the encryption key, and the counter reset step for resetting the counter for the first predetermined time and the second predetermined time. A program for causing a computer to execute the operation of the step, and a program that operates in cooperation with the computer.

  Further, the recording medium of the present invention includes the encrypted data transmission step of encrypting and transmitting content data of the encryption key update method of the present invention described above, the authentication / key exchange step of performing authentication and key exchange, All or part of the identifier transmitting step for transmitting an identifier, the encryption key updating step for updating the encryption key, and the counter reset step for resetting the counter for the first predetermined time and the second predetermined time A recording medium on which a program for causing a computer to execute all or part of the operations of the above steps is recorded, and is readable by the computer, and the read program is used in cooperation with the computer is there.

  The “partial steps” of the present invention means one or several steps out of the plurality of steps.

  The “step operation” of the present invention means the operation of all or part of the step.

  Further, one usage form of the program of the present invention may be an aspect in which the program is recorded on a computer-readable recording medium and operates in cooperation with the computer.

  Further, the recording medium includes a ROM and the like.

  The computer of the present invention described above is not limited to pure hardware such as a CPU, and may include firmware, an OS, and peripheral devices.

  As described above, the configuration of the present invention may be realized by software or hardware.

  As described above, the encrypted data transmitting apparatus, the encryption key updating method, and the electronic device according to the present invention can be used in the encrypted data transmitting apparatus to discard the original encryption key / update time (the last in the present embodiment). The second key update time (one hour 55 from the time when the transmission of the last encrypted data in this embodiment is completed), which is slightly smaller than the time when the transmission of the encrypted data is completed. When the encrypted data receiving apparatus transmits the authentication / key exchange request to the encrypted data transmitting apparatus after the second key update time has elapsed. The encryption key is updated earlier than the original key update timing, and the updated new encryption key is transmitted to the encrypted data receiving apparatus.

  By using the encrypted data transmission device, the encryption key update method, and the electronic device of the present invention, when the encrypted data transmission device receives an authentication / key exchange request, the first encryption key update time is shorter than the original encryption key update time. If the encryption key update time 2 has already passed, the encryption key Kx is transmitted to the encrypted data receiving apparatus after updating the encryption key, whereby authentication and key exchange are performed. It is possible to avoid the problem that the encrypted data is updated during the period from when the content data is requested until the encrypted data received by the encrypted data receiving apparatus is not correctly decrypted.

  The encrypted data transmitting apparatus, the encryption key updating method, and the electronic device according to the present invention are provided in the encrypted data transmitting apparatus when the encrypted data receiving apparatus requests the identifier assigned to the encryption key in the encrypted data transmitting apparatus. Is a second key update time (this embodiment) slightly shorter than the original encryption key destruction / update time (in this embodiment, two hours after the completion of transmission of the last encrypted data). In this form, the encrypted data receiving apparatus requests the encrypted data transmitting apparatus for the identifier of the encryption key. If the timing is after the second key update time has elapsed, the encryption key is updated earlier than the original key update timing, and the encrypted data receiving device is updated. It is intended to send the identifier of the new encryption key.

  By using the encrypted data transmitting apparatus, the encryption key updating method, and the electronic device of the present invention, when the encrypted data receiving apparatus requests the identifier of the encryption key from the encrypted data transmitting apparatus, the original encryption key If the second encryption key update time, which is shorter than the update time, has already elapsed, the encrypted data transmission device transmits the identifier of the encryption key after updating the encryption key. It becomes possible to avoid the problem that the encrypted data received by the encrypted data receiving apparatus is not correctly decrypted because the encryption key is updated after the inquiry is made until the content data is requested. .

  The encrypted data transmitting device, the encryption key updating method, and the electronic device according to the present invention have an effect that the received device can reliably decrypt the received encrypted data, and are used when performing encrypted data transmission. This is useful for encrypted data transmission devices, encryption key update methods, electronic devices, and the like.

The block diagram of the encryption data transmission / reception system in Embodiment 1 of this invention The figure which shows the update method of the encryption key in the encryption data transmission apparatus of Embodiment 1 of this invention. The figure which shows the update method of the encryption key in an encryption data transmission apparatus in case the encryption data reception apparatus refers to the identifier of an encryption key in Embodiment 1 of this invention. The figure which shows the processing flow at the time of the encryption data transmission apparatus of Embodiment 1 of this invention updating an encryption key and an encryption key identifier. Block diagram of a conventional encrypted data transmission / reception system The figure which shows the update method of the encryption key in the conventional conventional encryption data transmission apparatus. The figure which shows the update method of the encryption key in the conventional encryption data transmission apparatus when authentication and key exchange generate | occur | produce just before the time when an encryption key is updated.

Explanation of symbols

110 Encrypted data transmitting device 111 Encrypted data receiving device 100, 106, 120, 126 Time 101, 107, 123 Authentication / key exchange 102, 104, 108, 124 Content request 103, 105, 109, 125 Encrypted data 121 122 Identifier reference request 300 Hard disk 301 Data encryption transmission unit 302 Interface unit 303 Encryption key identifier 304 Encryption key register 305 Encryption key Kx
306 Request Analysis Control Unit 307 Authentication / Key Exchange Unit 308 Encryption Key Identifier Request Processing Unit 309 Ethernet 310 Kx Update Timer 311 Analysis Unit 312 Data Transmission Control Unit 313 Identifier Transmission Control Unit 314 Authentication Control Unit

Claims (8)

Encryption key storage means for storing an encryption key for encrypting content data to be transmitted;
Encrypted data transmission means for encrypting the content data using the encryption key and transmitting the encrypted data;
An authentication / key exchange means for performing authentication and key exchange with the encrypted data receiving device;
Whether or not the next encrypted data has been transmitted within the first predetermined time since the transmission of the encrypted data has been completed, and the first shorter than the first predetermined time since the completion of the transmission of the encrypted data. 2 after the elapse of a predetermined time of 2 and whether or not authentication and key exchange have been performed within the first predetermined time, and the next encrypted data is not transmitted within the first predetermined time. If the authentication and key exchange are not performed within the first predetermined time after the second predetermined time has elapsed, the encryption key is updated at the end of the first predetermined time. When the next encrypted data is not transmitted within the first predetermined time, and after the second predetermined time has elapsed, the authentication and key exchange are performed within the first predetermined time. Includes the encryption key during the authentication and key exchange. To update, and an encryption key update means,
The counters for the first predetermined time and the second predetermined time are a timing when transmission of encrypted data is completed, and after the second predetermined time has elapsed and within the first predetermined time. An encrypted data transmitting apparatus that is reset to a timing before transmitting the updated encryption key at the time of the authentication and key exchange when the authentication and key exchange are performed. An encryption key storage means for storing an encryption key for encrypting content data to be transmitted, and an identifier of the encryption key;
Encrypted data transmission means for encrypting the content data using the encryption key and transmitting the encrypted data;
An authentication / key exchange means for performing authentication and key exchange with the encrypted data receiving device;
Identifier transmitting means for transmitting the identifier to the encrypted data receiving device;
Whether or not the next encrypted data has been transmitted within the first predetermined time since the transmission of the encrypted data has been completed, and the first shorter than the first predetermined time since the completion of the transmission of the encrypted data. 2 after the elapse of a predetermined time of 2, and whether or not the identifier is transmitted within the first predetermined time, and the next encrypted data is not transmitted within the first predetermined time. When the identifier is not transmitted within the first predetermined time after the elapse of the predetermined time of 2, the encryption key and the identifier are updated at the end of the first predetermined time, and the first If the next encrypted data is not transmitted within a predetermined time of 1 and the identifier is transmitted within the first predetermined time after the second predetermined time has elapsed, the identifier is When sending the encryption key and To update the serial identifier, and an encryption key update means,
The counters for the first predetermined time and the second predetermined time are a timing when transmission of encrypted data is completed, and after the second predetermined time has elapsed and within the first predetermined time. An encrypted data transmitting apparatus that is reset to a timing before transmitting the updated identifier when the identifier is transmitted to An encrypted data transmission step of encrypting content data using an encryption key and transmitting the encrypted data;
An authentication / key exchange step for performing authentication and key exchange with the encrypted data receiving device;
Whether or not the next encrypted data has been transmitted within the first predetermined time since the transmission of the encrypted data has been completed, and the first shorter than the first predetermined time since the completion of the transmission of the encrypted data. 2 after the elapse of a predetermined time of 2 and whether or not authentication and key exchange have been performed within the first predetermined time, and the next encrypted data is not transmitted within the first predetermined time. If the authentication and key exchange are not performed within the first predetermined time after the second predetermined time has elapsed, the encryption key is updated at the end of the first predetermined time. When the next encrypted data is not transmitted within the first predetermined time, and after the second predetermined time has elapsed, the authentication and key exchange are performed within the first predetermined time. Includes the encryption key during the authentication and key exchange. To update, and the encryption key update step,
The timing when transmission of encrypted data is completed, and the authentication and key exchange when the authentication and key exchange are performed within the first predetermined time after the second predetermined time has elapsed. And a counter reset step of resetting the counters for the first predetermined time and the second predetermined time at a timing before transmitting the updated encryption key. An encrypted data transmission step of encrypting content data using an encryption key and transmitting the encrypted data;
An authentication / key exchange step for performing authentication and key exchange with the encrypted data receiving device;
An identifier transmission step of transmitting the encryption key identifier to the encrypted data receiving device;
Whether or not the next encrypted data has been transmitted within the first predetermined time since the transmission of the encrypted data has been completed, and the first shorter than the first predetermined time since the completion of the transmission of the encrypted data. 2 after the elapse of a predetermined time of 2, and whether or not the identifier is transmitted within the first predetermined time, and the next encrypted data is not transmitted within the first predetermined time. If the identifier is not transmitted within the first predetermined time after the elapse of the predetermined time of 2, the encryption key is updated at the end of the first predetermined time, and the first predetermined time is updated. When the identifier is transmitted within the first predetermined time after the second predetermined time elapses when the next encrypted data is not transmitted within the time, when transmitting the identifier Updating the encryption key and the identifier Carried out, and the encryption key update step,
The timing when the transmission of encrypted data is completed, and the updated identifier when the identifier is transmitted within the first predetermined time after the second predetermined time has elapsed And a counter reset step of resetting the counters of the first predetermined time and the second predetermined time at a timing before the encryption key update method.   An electronic apparatus comprising the encrypted data transmission device according to claim 1.   The encryption key update method according to claim 3, wherein the encrypted data transmission step of encrypting and transmitting content data, the authentication / key exchange step of performing authentication and key exchange, and the encryption of updating the encryption key A program for causing a computer to execute a key update step and the counter reset step of resetting a counter of the first predetermined time and the second predetermined time.   5. The encryption key update method according to claim 4, wherein the encrypted data transmission step of encrypting and transmitting content data, the authentication / key exchange step of performing authentication and key exchange, and the identifier transmission step of transmitting an identifier, A program for causing a computer to execute the encryption key update step for updating the encryption key, and the counter reset step for resetting a counter for the first predetermined time and the second predetermined time. A recording medium on which the program according to claim 6 or 7 is recorded, wherein the recording medium can be processed by a computer.

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