DATA TRANSMITTING/RECEIVING METHOD, DATA TRANSMITTER, DATA RECEIVER, DATA TRANSMITTING/RECEIVING SYSTEM, AV CONTENT TRANSMITTING METHOD, AV CONTENT RECEIVING METHOD, AV CONTENT TRANSMITTER, AV CONTENT RECEIVER, AND PROGRAM RECORDING MEDIUM

• US 6,834,111 B1
• Filed: 12/01/1999
• Issued: 12/21/2004
• Est. Priority Date: 04/01/1998
• Status: Expired due to Term

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Nishimura, Takuya, Takechi, Hideaki, Yamada, Masazumi, Gotoh, Shoichi, Iitsuka, Hiroyuki
• Primary Examiner(s): Barrón, Gilberto
• Assistant Examiner(s): Zand, Kambiz
• Application Number:
  US09/445,052
• Time in Patent Office: 1,847 Days
• Field of Search: 380/259, 380/281, 380/284, 380/245, 380/255, 713/171
• US Class Current: 380/255
• CPC Class Codes: H04H 20/69 Optical systems
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/0891 Revocation or update of secret information, e.g. encryption key update or rekeying

Abstract

A data transmitting and receiving method for improving transmission and reception efficiency can be obtained by improving the security through update of a control key and reduction of the frequency of the authentication and key exchange process. An STB 1 transmits encrypted digital data Kw (D) obtained by encrypting digital data D using a work key Kw, and an encrypted work key Kc (Kw) obtained by encrypting the Kw using a control key Kc. The Kc is periodically or non-periodically updated, and an identifier L identifying the Kc is assigned to each Kc. A VTR device 2 decrypts the received Kc (Kw) using the Kc obtained by performing the authentication and key exchange process with the STB 1, decrypts the Kw (D) received using the Kw to obtain the D. It is determined whether or not the Kc has been updated while the reception process is suspended by referring to the transmitted L when the reception process is suspended and then resumed. If it is determined that the Kc has been updated, then the authentication and key exchange process is performed again to obtain the updated Kc.

Claims

1. A data transmitting and receiving method comprising the steps of:

on a transmission side, encrypted digital data obtained by performing a first encryption process on digital data using a work key, and an encrypted work key obtained by performing a second encryption process on the work key using a control key, are transmitted, and

on a reception side, the encrypted work key is received and decrypted using the control key obtained by performing an authentication and key exchange process with the transmission side, and the encrypted digital data is received and decrypted using the decrypted work key, thereby obtaining the digital data,

on said transmission side, the control key is periodically or non-periodically updated, an identifier identifying the control key is assigned for each control key; and

on said reception side, when a reception process is suspended and then resumed, it is determined whether or not the control key has been updated while the reception process is being suspended by referring to the identifier transmitted from the transmission side, and, when it is determined that the control key has been updated, the authentication and key exchange process is performed again, thereby obtaining the updated control key;

wherein said reception side requests the transmission side to transmit the identifier when the reception process is suspended and then resumed; and

said transmission side transmits the identifier when the authentication and key exchange process is performed, and also transmits the identifier in response to the request;

the reception side receives the identifier transmitted from the transmission side, and

the reception side does not perform the authentication and key exchange process, based on the received identifier and determining that the control key has not been updated.

2. The data transmitting and receiving method according to claim 1, wherein said transmission side periodically or non-periodically transmits the identifier to said reception side.

3. The data transmitting and receiving method according to claim 2, wherein said transmission side periodically or non-periodically updates the work key, and transmits to the reception side the identifier, together with the work key, corresponding to the control key used when the first encryption process is performed on the work key.

4. The data transmitting and receiving method according to any one of claims 1 through 3, wherein said transmission side does not update the work key until the authentication and key exchange process is completed on the updated control key after the key encryption means updates the control key.

5. Data transmission and reception apparatus, comprising:

the data transmission apparatus including;

encryption means periodically or non-periodically updating/generating a work key, performing a first encryption process on digital data using the work key to convert the digital data into encrypted digital data, and transmitting the encrypted digital data to the data reception apparatus;

a key encryption means periodically or non-periodically updating/generating a control key, performing a second encryption process on the work key using the control key to convert the work key into encrypted work key, and transmitting the encrypted work key to the data reception apparatus;

a transmission side authentication and key exchange means performing an authentication and key exchange process with the data reception apparatus;

identifier generation means generating an identifier identifying the control key; and

identifier transmission means transmitting the identifier to the data reception apparatus; and

the data reception apparatus including;

a reception side authentication and key exchange means performing an authentication and key exchange process with the data transmission apparatus;

key restoration means restoring a work key by decrypting an encrypted work key converted by performing a second encryption process on the work key using a control key, said restoring process being performed using the control key obtained through said reception side authentication and key exchange means;

decryption means restoring digital data by decrypting encrypted digital data converted by performing a first encryption process on the digital data using the work key, said decrypting process being performed using the work key restored by said key restoration means; and

identifier recognition means determining whether or not the control key has been updated by referring to an identifier identifying the control key transmitted from said data transmission apparatus at least when a reception process is suspended and then resumed, and, when it is determined that the control key has been updated, instructing said reception side authentication and key exchange means to perform again the authentication and key exchange process to obtain the updated control key,

the identifier recognizing means receives the identifier-transmitted from the transmission apparatus and

the identifier recognizing means does not perform the authentication and key exchange process, based on the received identifier and determining that the control key has not been updated.

6. The data transmission apparatus according to claim 5, wherein said encryption means does not update the work key until the authentication and key exchange process is completed on the updated control key after the key encryption means updates the control key.

7. The data reception apparatus according to claim 5, comprising:

identifier storage means storing the identifier,

in which said identifier recognition means determines whether or not the control key has been updated by comparing a latest identifier transmitted from said data transmission apparatus with the identifier transmitted immediately before the latest identifier and stored in said identifier storage means.

8. The data transmission apparatus according to claim 6 or 5, wherein said identifier transmission means transmits the identifier when the authentication and key exchange process is performed, and also transmits the identifier in response to a request from said data reception apparatus.

9. The data reception apparatus according to claim 5 or 7, further comprising:

identifier request means requesting said data transmission apparatus to transmit the identifier when the reception process is suspended and then resumes.

10. The data transmission apparatus according to claim 6 or 5, wherein said identifier transmission means periodically or non-periodically transmit the identifier to said data reception apparatus.

11. The data transmission apparatus according to claim 10, wherein said identifier transmission means transmits to'"'"'said data reception apparatus the identifier corresponding to the control key used when the second encryption process is performed on the updated/generated work key each time the work key is updated/generated.

12. A computer readable program recording medium, characterized by storing a program for directing a computer to perform each function of all or a part of each component of the data transmission apparatus or the data reception apparatus according to any one of claims 5 through 7.

13. A data transmission and reception method, comprising the steps of:

on a transmission side, encrypted digital data obtained by performing an encryption process on digital, data using a work key is transmitted;

on a reception side, a control key required to obtain the work key is obtained by performing an authentication and key exchange process with said transmission side, and the received encrypted digital data is decrypted using the work key obtained using the control key to obtain the digital data, wherein;

said transmission side periodically and non-periodically updates the-control key, assigns an identifier identifying the control key for each control key, said reception side determines whether or not the control key has been updated while the reception process is suspended by referring to the identifier transmitted from the transmission side when the reception process is suspended and then resumed, and, when it is determined that the control key has been updated, obtains the updated control key by performing again the authentication and key exchange process, and

the reception side receives the identifier transmitted from the transmission side, and

the reception side does not perform the authentication and key exchange process, after receiving the identifier and determining that the control key has not been updated.

14. A data reception apparatus, comprising:

reception means receiving encrypted digital data obtained by encrypting digital data using a work key;

and a reception side authentication and key exchange means performing an authentication and key exchange process with a data transmission apparatus;

a control key obtaining means obtaining a control key required to obtain the work key through the reception side authentication and key exchange means;

decryption means decrypting the encrypted digital data using the work key generated using the control key to restoring the digital data; and

identifier recognition means determining whether or not the control key has been updated by referring to an identifier identifying the control key transmitted from the data transmission apparatus when the receiving process is suspended and then resumed, and, when it is determined that the control key has been updated, the updated control key is obtained by performing again the authentication and key exchange process with the reception side authentication and key exchange means

wherein said reception means requests the data transmission apparatus to transmit the identifier when the receiving process is suspended and then resumed;

said data transmission apparatus transmits the identifier in response to the request;

the reception means receives the identifier transmitted from the transmission side, and does not perform the authentication and key exchange process, based on the received identifier and determining that the control key has not been updated.