Content distribution system

• US 7,392,393 B2
• Filed: 01/09/2003
• Issued: 06/24/2008
• Est. Priority Date: 01/16/2002
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Taki, Ryuta
• Primary Examiner(s): Moazzami; Nasser
• Assistant Examiner(s): REZA, MOHAMMAD W
• Application Number:
  US10/469,703
• Publication Number:
  US 20040098592A1
• Time in Patent Office: 1,993 Days
• Field of Search: 713/176, 713/159, 176/155, 726/10
• US Class Current: 713/176
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: H04L 2463/101 applying security measures for digital rights management
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04L 63/18 using different networks or channels, e.g. using out of band channels cryptographic mechanisms or cryptographic arrangements for key distribution involving distinctive intermediate devices or communication paths H04L9/0827; cryptographic mechanisms or cryptographic arrangements for authentication using a plurality of channels H04L9/3215
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 21/25816 involving client authentication restricting access to computer systems by authenticating users using a predetermined code G06F21/33; cryptographic authentication protocols H04L9/32; networks authentication protocols H04L63/08; authentication in wireless network security H04W12/06
• CPC Class Codes: H04N 21/41407 embedded in a portable device, e.g. video client on a mobile phone, PDA, laptop constructional details of equipment or arrangements specially adapted for portable computer application G06F1/1626; arrangements specially adapted for mobile receivers in broadcast systems H04H20/57
• CPC Class Codes: H04N 21/4143 embedded in a Personal Computer [PC]
• CPC Class Codes: H04N 21/47202 for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 21/63345 by transmitting keys key distribution for secret or secure communication H04L9/08; network support of key management H04L63/06
• CPC Class Codes: H04N 21/6581 Reference data, e.g. a movie identifier for ordering a movie or a product identifier in a home shopping application
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests

Abstract

A system that allows secure processing in a case where a download-requesting terminal and a download-destination terminal are different devices is implemented. A content distribution server receives a ticket carrying a signature of a download destination from a terminal requesting downloading of content, and verifies the ticket to verify that a device serving as the download destination is a device authorized by the download-requesting terminal, thereby verifying the authenticity of the device serving as the download destination without directly authenticating the device serving as the download destination. Furthermore, a content-signing key [Ksig] or a hash value is exchanged as data that can be cryptographically processed only at the download-requesting device and the download-destination device, so that, for example, checking of the integrity of the content is allowed only at a legitimate download-destination device.

Claims

1. A content distribution system comprising:

a first information processing apparatus configured to issue a content-download request in which a download destination that is different from the first information processing apparatus itself is specified;

a second information processing apparatus that is specified as a download destination of content; and

a content distribution server configured to receive the content-download request from the first information processing apparatus and send the content to the second information processing apparatus,

wherein the first information processing apparatus sends a ticket carrying a digital signature of the second information processing apparatus to the content distribution server to authenticate that the second information processing apparatus is authorized to receive the content from the content distribution server, and

the content distribution server verifies the digital signature on the ticket, and on condition that the verification has succeeded, the content distribution server determines that the second information processing apparatus is a content-download destination authorized by the first information processing apparatus, and sends the content to the second information processing apparatus.

2. The content distribution system according to claim 1,

wherein the first information processing apparatus and the second information processing apparatus have a homenet-area shared secret key [Ksec] that serves as a shared secret key,

the first information processing apparatus sends encrypted key data [E(Ksec, Ksig)] to the second information processing apparatus via the content distribution server, the encrypted key data [E(Ksec, Ksig)] being obtained by encrypting, using the homenet-area shared secret key [Ksec], a content-signing key [Ksig] generated by the content distribution server, and

the second information processing apparatus verifies a signature on the content received from the content distribution server, using the content-signing key [Ksig] obtained by decrypting the encrypted key data [E(Ksec, Ksig)] using the homenet-area shared secret key [Ksec].

3. The content distribution system according to claim 1,

wherein the first information processing apparatus and the second information processing apparatus have a homenet-area shared secret key [Ksec] that serves as a shared secret key,

the first information processing apparatus sends an encrypted hash value [E(Ksec, H(M))] to the second information processing apparatus via the content distribution server, the encrypted hash value [E(Ksec, H(M))] being obtained by encrypting, using the homenet-area shared secret key [Ksec], a hash value [H(M)] of the content, generated by the content distribution server, and

the second information processing apparatus verifies the content received from the content distribution server, using the hash value [H(M)] of the content, obtained by decrypting the encrypted hash value [E(Ksec, H(M))] using the homenet-area shared secret key [Ksec].

4. The content distribution system according to claim 1,

wherein each of the first information processing apparatus and the second information processing apparatus has a public key and a secret key of a public-key cryptosystem,

the first information processing apparatus sends encrypted key data [E(K_SEC_MBL, Ksig)] to the second information processing apparatus via the content distribution server, the encrypted key data [E(K_SEC_MBL, Ksig)] being obtained by encrypting, using the secret key [K_SEC_MBL] of the first information processing apparatus, a content-signing key [Ksig] generated by the content distribution server, and

the second information processing apparatus verifies a signature on the content received from the content distribution server, using the content-signing key [Ksig] obtained by decrypting the encrypted key data [E(K_SEC_MBL, Ksig)] using the public key [K_PUB_MBL] of the first information processing apparatus.

5. The content distribution system according to claim 1,

wherein each of the first information processing apparatus and the second information processing apparatus has a public key and a secret key of a public-key cryptosystem,

the first information processing apparatus sends an encrypted hash value [E(K_SEC_MBL, H(M))] to the second information processing apparatus via the content distribution server, the encrypted hash value [E(K_SEC_MBL, H(M))] being obtained by encrypting, using the secret key [K_SEC_MBL] of the first information processing apparatus, a hash value [H(M)] of the content, generated by the content distribution server, and

the second information processing apparatus verifies a signature on the content received from the content distribution server, using the hash value [H(M)] of the content, obtained by decrypting the encrypted hash value [E(K_SEC_MBL, H(M))] using the public key [K_PUB_MBL] of the first information processing apparatus.

6. The content distribution system according to claim 1,

wherein the ticket is obtained by applying a digital signature on data including respective identifiers (IDs) of the first information processing apparatus and the second information processing apparatus, using a secret key of the second information processing apparatus, and

the content distribution server verifies the digital signature on the ticket using a public key of the second information processing apparatus.

7. The content distribution system according to claim 1, wherein the content distribution server verifies the digital signature on the ticket by:

(a) verifying the validity of a public-key certificate of the second information processing apparatus by verifying a signature on the public-key certificate (a signature of a certificate authority),

(b) obtaining a public key of the second information processing apparatus from the public-key certificate whose validity has been verified, and

(c) verifying the signature on the ticket of the second information processing apparatus using the public key of the second information processing apparatus.

8. A content distribution method for a content distribution system:

at a first information processing apparatus configured to issue a content-download request in which a download destination that is different from the first information processing apparatus itself is specified,

sending, by the first information processing apparatus, a ticket carrying a digital signature of a second information processing apparatus to a content distribution server to authenticate that the second information processing apparatus is authorized to receive the content from the content distribution server,

the second information processing apparatus being specified as a download destination of the content; and

at the content distribution server configured to receive the content-download request from the first information processing apparatus and to send the content to the second information processing apparatus,

verifying the digital signature on the ticket,

determining, on condition that the verification has succeeded, that the second information processing apparatus is a content-download destination authorized by the first information processing apparatus, and

sending the content to the second information processing apparatus.

9. The content distribution method according to claim 8,

wherein the first information processing apparatus sends encrypted key data [E(Ksec, Ksig)] to the second information processing apparatus via the content distribution server, the encrypted key data [E(Ksec, Ksig)] being obtained by encrypting, using a homenet-area shared secret key [Ksec] that serves as a secret key shared by the first information processing apparatus and the second information processing apparatus, a content-signing key [Ksig] generated by the content distribution server, and

the second information processing apparatus verifies a signature on the content received from the content distribution server, using the content-signing key [Ksig] obtained by decrypting the encrypted key data [E(Ksec, Ksig)] using the homenet-area shared secret key [Ksec].

10. The content distribution method according to claim 8,

wherein the first information processing apparatus sends an encrypted hash value [E(Ksec, H(M))] to the second information processing apparatus via the content distribution server, the encrypted hash value [E(Ksec, H(M))] being obtained by encrypting, using a homenet-area shared secret key [Ksec] that serves as a secret key shared by the first information processing apparatus and the second information processing apparatus, a hash value [H(M)] of the content, generated by the content distribution server, and

the second information processing apparatus verifies the content received from the content distribution server, using the hash value [H(M)] of the content, obtained by decrypting the encrypted hash value [E(Ksec, H(M))] using the homenet-area shared secret key [Ksec].

11. The content distribution method according to claim 8,

wherein the first information processing apparatus sends encrypted key data [E(K_SEC_MBL, Ksig)] to the second information processing apparatus via the content distribution server, the encrypted key data [E(K_SEC_MBL Ksig)] being obtained by encrypting, using a secret key [K_SEC_MBL] of the first information processing apparatus, a content-signing key [Ksig] generated by the content distribution server, and

the second information processing apparatus verifies a signature on the content received from the content distribution server, using the content-signing key [Ksig] obtained by decrypting the encrypted key data [E(K_SEC_MBL, Ksig)] using a public key [K_PUB_MBL] of the first information processing apparatus.

12. The content distribution method according to claim 8, wherein the first information processing apparatus sends an encrypted hash value [E(K_SEC_MBL, H(M))] to the second information processing apparatus via the content distribution server, the encrypted hash value [E(K_SEC_MBL, H(M))] being obtained by encrypting, using a secret key [K_SEC_MBL] of the first information processing apparatus, a hash value [H(M)] of the content, generated by the content distribution server, and

the second information processing apparatus verifies the content received from the content distribution server, using the hash value [H(M)] of the content, obtained by decrypting the encrypted hash value [E(K_SEC_MBL, H(M))] using a public key [K_PUB_MBL] of the first information processing apparatus.

13. The content distribution method according to claim 8,

wherein the ticket is obtained by applying a digital signature on data including respective identifiers (IDs) of the first information processing apparatus and the second information processing apparatus, using a secret key of the second information processing apparatus, and

the content distribution server verifies the digital signature on the ticket using a public key of the second information processing apparatus.

14. The content distribution method according to claim 8,

wherein the content distribution server verifies the digital signature on the ticket by:

(a) verifying the validity of a public-key certificate of the second information processing apparatus by verifying a signature on the public-key certificate (a signature of a certificate authority),

(b) obtaining a public key of the second information processing apparatus from the public-key certificate whose validity has been verified, and

(c) verifying the signature on the ticket of the second information processing apparatus using the public key of the second information processing apparatus.

15. A first information processing apparatus, comprising:

storage means that stores a ticket carrying a digital signature of a second information processing apparatus that serves as a download destination of content;

control means for generating a content-download request, in which the download destination that is different from the first information processing apparatus itself is specified, including the ticket stored in the storage means; and

communication means for sending the content-download request, from the first information processing apparatus, including the ticket carrying the digital signature of the second information processing apparatus to a content distribution server to authenticate that the second information processing apparatus is authorized to receive the content from the content distribution server, the content distribution server configured to verify the digital signature on the ticket, and on condition that the verification has succeeded, the content distribution server configured to determine that the second information processing apparatus is a content-download destination authorized by the first information processing apparatus, and to send the content to the second information processing apparatus.

16. The first information processing apparatus according to claim 15,

wherein the control means of the first information processing apparatus generates encrypted key data [E(Ksec, Ksig)] as data to be transmitted to the second information processing apparatus, the encrypted key data [E(Ksec, Ksig)] being obtained by encrypting, using a homenet-area shared secret key [Ksec] that serves as a secret key shared by the first information processing apparatus and the second information processing apparatus, a content-signing key [Ksig] generated by the content distribution server.

17. The first information processing apparatus according to claim 15,

wherein the control means of the first information processing apparatus generates an encrypted hash value [E(Ksec, H(M))] as data to be transmitted to the second information processing apparatus, the encrypted hash value [E(Ksec, H(M))] being obtained by encrypting, using a homenet-area shared secret key [Ksec] that serves as a secret key shared by the first information processing apparatus and the second information processing apparatus, a hash value [H(M)] of the content, generated by the content distribution server.

18. The first information processing apparatus according to claim 15,

wherein the control means of the first information processing apparatus generates encrypted key data [E(K_SEC_MBL, Ksig)] as data to be transmitted to the second information processing apparatus, the encrypted key data [E(K_SEC_MBL, Ksig)] being obtained by encrypting, using a secret key [K_SEC_MBL] of the first information processing apparatus, a content-signing key [Ksig] generated by the content distribution server.

19. The first information processing apparatus according to claim 15,

wherein the control means of the first information processing apparatus generates an encrypted hash value [E(K_SEC_MBL, H(M))] as data to be transmitted to the second information processing apparatus, the encrypted hash value [E(K_SEC_MBL, H(M))] being obtained by encrypting, using a secret key [K_SEC_MBL] of the first information processing apparatus, a hash value [H(M)] of the content, generated by the content distribution sever.

20. A computer storage medium, storing computer executable instructions that cause a computer to implement a method, comprising:

obtaining a ticket carrying a digital signature of a second information processing apparatus that serves as a download destination of content;

generating a content-download-request, in which the download destination that is different from a first information processing apparatus that executes the instructions is specified, including the ticket; and

sending, from the first information processing apparatus, the content-download-request including the ticket to a content distribution server to authenticate that the second information processing apparatus is authorized to receive the content from the content distribution server, the content distribution server configured to verify the digital signature on the ticket, and on condition that the verification has succeeded, the content distribution server configured to determine that the second information processing apparatus is a content-download destination authorized by the first information processing apparatus, and to send the content to the second information processing apparatus.

21. A computer storage medium, storing computer executable instructions that cause a computer to implement a method of sending content, said method comprising:

receiving by a content distribution server, from a first information processing apparatus, a content-download-request process in which a second information processing apparatus is specified as a download destination that is different from the first information processing apparatus itself, and a ticket carrying a digital signature of the second information processing apparatus;

verifying, by the content distribution server, the digital signature included in the ticket carrying the digital signature of the second information processing apparatus serving as the download destination, the ticket being included in the content-download request to authenticate that the second information processing apparatus is authorized to receive the content from the content distribution server; and

sending, by the content distribution server, content to the second information processing apparatus on condition that the verification has succeeded.