Method of controlling content access and method of obtaining content key using the same

• US 20060179478A1
• Filed: 12/15/2005
• Published: 08/10/2006
• Est. Priority Date: 01/19/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Bong-seon, Yoon, Young-sun, Han, Sung-hyu, Lee, Sun-nam, Lee, Jae-heung, Kim, Myung-sun
• Granted Patent: US 8,341,402 B2
• Time in Patent Office: Days
• US Class Current: 726/5
• 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 9/0833 involving conference or group key network architectures or network communication protocols for key management in group communication in a packet data network H04L63/065
• CPC Class Codes: H04L 9/3226 using a predetermined code, e.g. password, passphrase or PIN network architectures or network communication protocols for supporting authentication of entities using passwords in a packet data network H04L63/083

Abstract

Provided is a method of controlling content access in a home network. The method includes: (a) defining a predetermined sub group and allocating a sub group key for the sub group; and (b) checking whether a user belongs to the sub group and transmitting the sub group key to a user device requested by the user, wherein the user device obtains an encrypted content key using a domain key and the sub group key. Since a content key is twice encrypted using a domain key and a sub group key and transmitted to a user device, it is possible to provide authorized content access to a user.

Claims

1. A method of controlling content access in a home network, comprising:

(a) defining a predetermined sub group and allocating a sub group key for the sub group; and

(b) checking whether a user belongs to the sub group and transmitting the sub group key to a user device requested by the user,

wherein the user device obtains an encrypted content key using a domain key and the sub group key.

2. The method of claim 1, further comprising:

encrypting a content key using the domain key to generate a first encrypted content key;

encrypting the first encrypted content key using the sub group key to generate a second encrypted content key; and

transmitting the second encrypted content key and the domain key to the user device.

3. The method of claim 1, wherein operation (b) comprises:

receiving a user identifier and a password from the user;

checking whether the user identifier and the password are identical to a user identifier and a user password within the sub group; and

when checking indicates that user identifiers are identical to each other and that passwords are identical to each other, transmitting a sub group key of the sub group to the user device.

17. A computer-readable storage medium having embodied thereon a computer program for executing the method of claim 1.

4. A method of obtaining a content key by a user device in a home network, the method comprising:

a home server determining a sub group to which a user belongs using a user identifier and a user password received from the user and transmitting a sub group key allocated to the determined sub group to the user device;

the user device receiving an encrypted content key and a domain key from the home server; and

the user device decrypting the encrypted content key using the domain key and the sub group key.

5. The method of claim 4, wherein the encrypted content key is generated by encrypting a content key twice using the domain key and the sub group key.

6. A method of controlling content access in a home network, comprising:

(a) defining a predetermined sub group and allocating a generator and sub group public information to the sub group;

(b) generating a sub group key of the sub group using a supervisor password;

(c) generating an authentication function value using the supervisor password PW1 and a user password; and

(d) transmitting the authentication function value and sub group public information to the user device,

wherein the sub group public information is generated using the generator and the supervisor password and the user device obtains the sub group key from the authentication function value and sub group public information.

7. The method of claim 6, wherein operation (a) is given by Equation,

$\begin{array}{c}\mathrm{SGPI}=\{x❘\end{array}$

x = g h j ⁡

( PW ⁢

 

⁢

1 ) , ( 1 ⁢

DjDt ) } = { x 1 , x 2 , …

⁢

 

, x t } = { g h 1 ⁡

( PW ⁢

 

⁢

1 ) , g h 2 ⁡

( PW ⁢

 

⁢

1 ) , …

⁢

 

, g h t ⁡

( PW ⁢

 

⁢

1 ) }

wherein, SGPI denotes sub group public information, PW1 denotes a supervisor password, g denotes a generator, h( ) denotes a hash function, t denotes a random number, and hˆ

j( ) denotes j times hash repetition.

8. The method of claim 7, wherein operation (b) is given by Equation,

SGK=g^(PW1),

wherein SGK denotes a sub group key, PW1 denotes a supervisor password, and g denotes a generator.

9. The method of claim 8, operation (c) is given by Equation,

$\mathrm{Ai}=\mathrm{PW}$

 

⁢

1 - Q j = 1 t ⁡

[ h j ⁡

( PW ⁢

 

⁢

1 ) * ( PWi ) j ] ⁢

mod ⁢



G 

,

wherein, Ai denotes an authentication function value of a user Ui, PW1 denotes a supervisor password, PWi denotes a user password of the user Ui, t denotes a random number, and G denotes a generation group of the generator g.

10. The method of claim 8, further comprising:

(e) encrypting a content key using a domain key to generate a first encrypted content key, encrypting the first encrypted content key using the sub group key to generate a second encrypted content key, and

(f) transmitting the second encrypted content key and the domain key DK to the user device.

11. The method of claim 10, wherein the random number t is given by the Equation,

t=i−

1,

wherein, i is a user serial number.

12. A method of obtaining a content key by a user device in a home network, the method comprising:

(a) a home server determining a sub group to which a user belongs using a user identifier and a user password received from the user and allocating a generator and sub group public information to the sub group;

(b) the user device receiving an encrypted content key, a domain key, an authentication function value, and the sub group public information from the home server;

(c) the user device generating a sub group key using the authentication function value and the sub group public information; and

(d) the user device decrypting the encrypted content key using the sub group key and the domain key to generate a content key,

wherein the sub group public information is generated using a generator and a supervisor password, and the authentication function value is generated using the supervisor password and the user password.

13. The method of claim 12, wherein the sub group public information is given by Equation,

$\begin{array}{c}\mathrm{SGPI}=\{x❘\end{array}$

x = g h j ⁡

( PW ⁢

 

⁢

1 ) , ( 1 ⁢

DjDt ) } = { x 1 , x 2 , …

⁢

 

, x t } = { g h 1 ⁡

( PW ⁢

 

⁢

1 ) , g h 2 ⁡

( PW ⁢

 

⁢

1 ) , …

⁢

 

, g h t ⁡

( PW ⁢

 

⁢

1 ) }

wherein, SGPI denotes sub group public information, PW1 denotes a supervisor password, g denotes a generator, h( ) denotes a hash function, t denotes a random number, and hˆ

j( ) denotes j times hash repetition.

14. The method of claim 13, wherein the authentication function value is given by Equation,

$\mathrm{Ai}=\mathrm{PW}$

 

⁢

1 - Q j = 1 t ⁡

[ h j ⁡

( PW ⁢

 

⁢

1 ) * ( PWi ) j ] ⁢

mod ⁢



G 

wherein, Ai denotes an authentication function value of a user Ui, PW1 denotes a supervisor password, PWi denotes a user password of the user Ui, t denotes a random number, and G denotes a generation group of the generator g.

15. The method of claim 14, wherein the random number t is given by the Equation,

t=i−

1

wherein, i is a user serial number.

16. The method of claim 12, wherein operation c) is given by Equation,

${\mathrm{SGK}}^{\prime }$

= g Ai * O j = 1 t ⁡

[ ( g h j ⁡

( PW ⁢

 

⁢

1 ) ) ( PWi ) j ]

wherein, SGK denotes a sub group key, PW1 denotes a supervisor password, PWi denotes a user password of the user Ui, Ai denotes an authentication function value of a user Ui, g denotes a generator, and t denotes a random number.