Use of licensed content without identification thereof

• US 20070083469A1
• Filed: 10/11/2005
• Published: 04/12/2007
• Est. Priority Date: 10/11/2005
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Kaufman, Charles
• Granted Patent: US 8,706,635 B2
• Time in Patent Office: Days
• US Class Current: 705/51
• 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: H04N 21/2541 Rights Management protecting software against unauthorised usage in a vending or licensing environment G06F21/10; security in data switching network management H04L41/28; security management or policies for network security H04L63/20; access security in wireless networks H04W12/08
• CPC Class Codes: H04N 21/25866 Management of end-user data customer care in data networks H04L41/5077
• CPC Class Codes: H04N 21/25875 involving end-user authentication restricting access to computer systems by authenticating users using a predetermined code G06F21/33; arrangements for secret or secure communication including means for verifying the identity or authority of a user of the system 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 21/4627 Rights management associated to the content security in data switching network management H04L41/28; security management or policies for network security H04L63/20; access security in wireless networks H04W12/08
• CPC Class Codes: H04N 21/63775 for uploading keys, e.g. for a client to communicate its public key to the server key management H04L9/08; network support of key management H04L63/06
• CPC Class Codes: H04N 21/835 Generation of protective data, e.g. certificates protecting software against unauthorised usage in a vending or licensing environment G06F21/10
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests

Abstract

A content key (CK) to decrypt a piece of encrypted content is obtained encrypted according to a public key of a licensor (PU-L) to result in (PU-L(CK)). (PU-L(CK)) is obscured according to (PU-L) and a value R to result in Obs (PU-L(CK)), and Obs (PU-L(CK)) is sent to the licensor, which applies a private key (PR-L) corresponding to (PU-L) to Obs (PU-L(CK)) to result in Obs (CK) as an obscured version of (CK). Obs (CK) is received from the licensor; and (CK) is obtained from Obs (CK) based on applying R thereto. The licensor cannot identify from Obs (PU-L(CK)) or from Obs (CK) the encrypted content or the content key (CK) from which the encrypted content may be identified.

Claims

1. A method in connection with a piece of encrypted digital content, the method for a user to obtain a content key (CK) to decrypt the encrypted content and comprising:

obtaining (CK) encrypted according to a public key of a licensor (PU-L) to result in (PU-L(CK)), and obtaining (PU-L) itself;

selecting a value R;

obscuring (PU-L(CK)) according to (PU-L) and R to result in Obs (PU-L(CK));

sending Obs (PU-L(CK)) to the licensor, the licensor applying a private key (PR-L) corresponding to (PU-L) to Obs (PU-L(CK)) to result in Obs (CK) as an obscured version of (CK);

receiving Obs (CK) from the licensor; and

obtaining (CK) from Obs (CK) based on applying R thereto,

whereby the licensor cannot identify from Obs (PU-L(CK)) or from Obs (CK) the encrypted content or the content key (CK) from which the encrypted content may be identified.

2. The method of claim 1 in connection with a piece of digital content encrypted according to a symmetric content key (CK) to result in (CK(content)), the method for a user to obtain (CK) to decrypt (CK(content)).

3. The method of claim 1 further comprising obtaining the encrypted content from a package containing same and obtaining (PU-L(CK)) and (PU-L) from the package.

4. The method of claim 1 further comprising obtaining the encrypted content in a streamed form from a distributor, and obtaining (PU-L(CK)) and (PU-L) from a listing in a menu from the distributor, the listing identifying the content and including such (PU-L(CK)) and (PU-L).

5. The method of claim 1 wherein obscuring (PU-L(CK)) according to (PU-L) and R comprises:

determining from the public key (PU-L) constituent values including a public exponent e and a modulus n;

computing;

Y=R^e mod n,

and multiplying (PU-L(CK)) by Y to result in Obs (PU-L(CK)),

whereby such Obs (PU-L(CK)) is;

Obs(PU-L(CK))=(R*CK)^e mod n.

6. The method of claim 1 comprising sending Obs (PU-L(CK)) to the licensor along with a form of payment for being provided with (CK) to decrypt the encrypted content.

7. The method of claim 1 further comprising the licensor applying the private key (PR-L) corresponding to (PU-L) to Obs (PU-L(CK)) to result in Obs (CK), including:

determining from the private key (PU-L) constituent values including a private exponent d and a modulus n;

computing (PR-L(Obs (PU-L(CK))) as;

(PR-L(Obs(PU-L(CK)))=(Obs(PU-L(CK)))^d mod n,

whereby such (PR-L(Obs (PU-L(CK))) is Obs (CK), which is;

Obs(CK)=(R*CK)mod n.

8. The method of claim 1 wherein obtaining (CK) from Obs (CK) based on applying R thereto comprises dividing Obs(CK) by R, including:

computing Obs (CK)/R as;

Obs(CK)/R=(R*CK)mod n*(1/R)mod n=(CK).

9. The method of claim 1 further comprising applying (CK) to the encrypted content to reveal same and rendering the revealed content.

10. The method of claim 1 for a user to obtain a plurality of content keys (CK1 . . . n) to decrypt the encrypted content and comprising, for each content key (CK1 . . . n):

obtaining (CKx) encrypted according to a public key of a licensor (PU-L) to result in (PU-L(CKx)), and obtaining (PU-L) itself;

selecting a value R;

obscuring (PU-L(CKx)) according to (PU-L) and R to result in Obs (PU-L(CKx));

sending Obs (PU-L(CKx)) to the licensor, the licensor applying a private key (PR-L) corresponding to (PU-L) to Obs (PU-L(CKx)) to result in Obs (CKx) as an obscured version of (CKx);

receiving Obs (CKx) from the licensor; and

obtaining (CKx) from Obs (CKx) based on applying R thereto,

whereby the licensor cannot identify from Obs (PU-L(CKx)) or from Obs (CKx) the encrypted content or the content key (CKx) from which the encrypted content may be identified.

11. A computer-readable medium having stored thereon computer-executable instructions for implementing a method in connection with a piece of encrypted digital content, the method for a user to obtain a content key (CK) to decrypt the encrypted content and comprising:

obtaining (CK) encrypted according to a public key of a licensor (PU-L) to result in (PU-L(CK)), and obtaining (PU-L) itself;

selecting a value R;

obscuring (PU-L(CK)) according to (PU-L) and R to result in Obs (PU-L(CK));

sending Obs (PU-L(CK)) to the licensor, the licensor applying a private key (PR-L) corresponding to (PU-L) to Obs (PU-L(CK)) to result in Obs (CK) as an obscured version of (CK);

receiving Obs (CK) from the licensor; and

obtaining (CK) from Obs (CK) based on applying R thereto,

whereby the licensor cannot identify from Obs (PU-L(CK)) or from Obs (CK) the encrypted content or the content key (CK) from which the encrypted content may be identified.

12. The medium of claim 11 in connection with a piece of digital content encrypted according to a symmetric content key (CK) to result in (CK(content)), the method for a user to obtain (CK) to decrypt (CK(content)).

13. The medium of claim 11 wherein the method further comprises obtaining the encrypted content from a package containing same and obtaining (PU-L(CK)) and (PU-L) from the package.

14. The medium of claim 11 wherein the method further comprises obtaining the encrypted content in a streamed form from a distributor, and obtaining (PU-L(CK)) and (PU-L) from a listing in a menu from the distributor, the listing identifying the content and including such (PU-L(CK)) and (PU-L).

15. The medium of claim 11 wherein obscuring (PU-L(CK)) according to (PU-L) and R comprises:

determining from the public key (PU-L) constituent values including a public exponent e and a modulus n;

computing;

Y=R^e mod n,

and multiplying (PU-L(CK)) by Y to result in Obs (PU-L(CK)),

whereby such Obs (PU-L(CK)) is;

Obs(PU-L(CK))=(R*CK)^e mod n.

16. The medium of claim 11 wherein the method comprises sending Obs (PU-L(CK)) to the licensor along with a form of payment for being provided with (CK) to decrypt the encrypted content.

17. The medium of claim 11 wherein the method further comprises the licensor applying the private key (PR-L) corresponding to (PU-L) to Obs (PU-L(CK)) to result in Obs (CK), including:

determining from the private key (PU-L) constituent values including a private exponent d and a modulus n;

computing (PR-L(Obs (PU-L(CK))) as;

(PR-L(Obs(PU-L(CK)))=(Obs(PU-L(CK)))^d mod n,

whereby such (PR-L(Obs (PU-L(CK))) is Obs (CK), which is;

Obs(CK)=(R*CK)mod n.

18. The medium of claim 11 wherein obtaining (CK) from Obs (CK) based on applying R thereto comprises dividing Obs(CK) by R, including:

computing Obs (CK)/R as;

Obs(CK)/R=(R*CK)mod n*(1/R)mod n=(CK).

19. The medium of claim 11 wherein the method further comprises applying (CK) to the encrypted content to reveal same and rendering the revealed content.

20. The medium of claim 11 wherein the method is for a user to obtain a plurality of content keys (CK1 . . . n) to decrypt the encrypted content and comprising, for each content key (CK1 . . . n):

obtaining (CKx) encrypted according to a public key of a licensor (PU-L) to result in (PU-L(CKx)), and obtaining (PU-L) itself;

selecting a value R;

obscuring (PU-L(CKx)) according to (PU-L) and R to result in Obs (PU-L(CKx));

sending Obs (PU-L(CKx)) to the licensor, the licensor applying a private key (PR-L) corresponding to (PU-L) to Obs (PU-L(CKx)) to result in Obs (CKx) as an obscured version of (CKx);

receiving Obs (CKx) from the licensor; and

obtaining (CKx) from Obs (CKx) based on applying R thereto,

whereby the licensor cannot identify from Obs (PU-L(CKx)) or from Obs (CKx) the encrypted content or the content key (CKx) from which the encrypted content may be identified.