INFORMATION ENCRYPTION APPARATUS AND CONTROLLING METHOD OF THE SAME, COMPUTER PROGRAM AND COMPUTER READABLE STORAGE MEDIUM

• US 20080152133A1
• Filed: 12/21/2006
• Published: 06/26/2008
• Est. Priority Date: 09/01/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: SUGA, Yuji
• Granted Patent: US 8,000,472 B2
• Time in Patent Office: Days
• US Class Current: 380/45
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 9/0836 using tree structure or hierarchical structure

Abstract

The present invention stores and manages only one piece of key information even if contents information includes a plurality of partial contents arranged in a sequence, and the partial contents are encrypted with different keys. When a piece of contents information includes four partial contents or divided into four partial contents, a key for each of four node positions is generated through four steps of operations from a key for the top root. Node keys P (i, 1) and P (i, i) at both sides are generated by a one-way function from node keys P (i−1, 1) and P (i−1, i−1) at the upper i−1^th layer, and a node key P (i, m) (m=2, 3, . . . , i−1) are generated by a one-way function which can generate the keys from any of node keys P (i−1, m−1) and P (i−1, m) at the upper i−1^th layer, where j^th node key at the i^th layer is represented as P (i, j) (j=1, 2, . . . , i−1). Then, each of partial contents is encrypted with key information generated at a terminal layer. If only a root key is saved, one encrypting key can be generated for a range of partial contents arranged in a sequence.

Claims

1. An information encrypting apparatus comprising:

hierarchical structure key generating means for generating key information on partial contents arranged in a sequence along a predetermined axis from root key information of contents information including said partial contents, wherein said root key information cannot be generated from said key information on partial contents;

encrypting means for encrypting said partial contents by using key information on partial contents generated by said hierarchical structure key generating means; and

storing means for storing encrypted contents information including partial contents encrypted by the encrypting means, said root key information and information for determining a boundary position of said partial contents.

2. The information encrypting apparatus according to claim 1, further comprising designating means for designating a boundary position of partial contents from said contents information.

11. The information encrypting apparatus according to claim 1, further comprising designating means for designating a boundary position of contents information, and wherein said partial contents are determined between boundary positions designated by said designating means or between a terminal of said contents and the closest boundary position.

3. An information encrypting method comprising:

a hierarchical structure key generating step of generating key information on partial contents arranged in a sequence along a predetermined axis from root key information of contents information including said partial contents, wherein said root key information cannot be generated from said key information on partial contents;

an encrypting step of encrypting said partial contents by using key information on partial contents generated at said hierarchical structure key generating step; and

a storing step of storing encrypted contents information including partial contents encrypted at the encrypting step, said root key information and information for determining a boundary position of said partial contents in a predetermined storage.

4. The information, encrypting method according to claim 3, further comprising a designating step of designating a boundary position of partial contents from said contents information.

5. A computer program for performing a control method of an information encrypting method according to claim 3.

6. A computer readable storage medium which stores the program according to claim 5 and can be read by a computer.

7. An information encrypting apparatus for encrypting contents information including partial contents arranged in a sequence along a predetermined axis, comprising:

root key generating means for generating root key information of said contents information;

hierarchical structure key generating means for generating i keys of the i^th layer based on i−

1 keys at an upper i−

1^th layer and generating key information for the number of said partial contents at a terminal position, wherein the hierarchical structure key generating means generates node keys P (i,

     1) and P (i, i) at both sides by a one-way function from node keys P (i−

1,

     1) and P (i−

1, i−

1) at the upper i−

1^th layer, and a node key P (i, m) (m=2, 3, . . . , i−

1) by a one-way function which can generate the keys from any of node keys P (i−

1, m−

1) and P(i−

1, m) at the upper i−

1^th layer, where j^th node key at the i^th layer is represented as P (i, j) (j=1, 2, . . . , i−

1);

encrypting means for encrypting each of partial contents by using key information at a terminal layer generated by said hierarchical structure key generating means; and

storing means for storing encrypted contents information including partial contents encrypted by the encrypting means, said root key information and information for determining a boundary position for each of partial contents.

8. The information encrypting apparatus according to claim 7, wherein said root key generating means comprises inputting means for inputting pieces of data in the number corresponding to the number of said partial contents and generates root key information based on data inputted by the inputting means.

9. The information encrypting apparatus according to claim 7, further comprising designating means for designating a boundary position for each partial contents from said contents information.

10. The information encrypting apparatus according to claim 7, wherein said contents information includes moving image information, audio information and document information.

12. An information delivering apparatus for delivering key information for decrypting contents encrypted in the information encrypting apparatus according to claim 7, comprising:

determining means for determining a rage of partial contents to be decrypted;

second hierarchical structure key generating means for generating hierarchical key information to be decrypted based on root key information stored in said storing means, wherein said second hierarchical structure key generating means generates node keys P (i,

     1) and P (i, i) at both sides by a one-way function from node keys P (i−

1,

     1) and P (i−

1, i−

1) at the upper i−

1^th layer, and a node key P (i, m) (m=2, 3, . . . , i−

1) by a one-way function which can generate the keys from any of node keys P (i−

1, m−

1) and P(i−

1, m) at the upper i−

1^th layer, where j^th node key at the i^th layer is represented as P (i, j) (j=1, 2, . . . , i−

1); and

delivering means for delivering decrypting information including key information on the lowest node among the nodes, which are the children node of all the nodes at terminal position corresponding to a range for partial contents determined by said determining means and information indicating at least a boundary position for each partial contents in said range for partial contents.

14. A control method in an information delivering apparatus for delivering key information for decrypting contents encrypted in the information encrypting apparatus according to claim 7, comprising:

a determining step of determining a rage of partial contents to be decrypted;

a second hierarchical structure key generating step of generating hierarchical key information to be decrypted based on root key information stored in said storing means, wherein node keys P (i,

     1) and P (i, i) at both sides are generated by a one-way function from node keys P (i−

1,

     1) and P (i−

1, i−

1) at the upper i−

1^th layer, and a node key P (i, m) (m=2, 3, . . . , i−

1) are generated by a one-way function which can generate the keys from any of node keys P (i−

1, m−

1) and P(i−

1, m) at the upper i−

1^th layer, where j^th node key at the i^th layer is represented as P (i, j) (j=1, 2, . . . , i−

1); and

a delivering step of delivering decrypting information including key information on the lowest node among the nodes, which are the children node of all the nodes at terminal position corresponding to a range for partial contents determined at said determining step and information indicating at least a boundary position for each partial contents in said range for partial contents.

16. A computer program that functions as an information delivering apparatus for delivering key information for decrypting contents encrypted in the information encrypting apparatus according to claim 7, when read in a computer, wherein said computer program functions as:

determining means for determining a rage of partial contents to be decrypted;

second hierarchical structure key generating means for generating hierarchical key information to be decrypted based on root key information stored in said storing means, wherein said second hierarchical structure key generating means generates node keys P (i,

     1) and P (i, i) at both sides by a one-way function from node keys P (i−

1,

     1) and P (i−

1, i−

1) at the upper i−

1^th layer, and a node key P (i, m) (m=2, 3, . . . , i−

1) by a one-way function which can generate the keys from any of node keys P (i−

1, m−

1) and P(i−

1, m) at the upper i−

1^th layer, where j^th node key at the i^th layer is represented as P (i, j) (j=1, 2, . . . , i−

1); and

delivering means for delivering decrypting information including key information on the lowest node among the nodes, which are the parent node of all the nodes at terminal position corresponding to a range for partial contents determined by said determining means and information indicating at least a boundary position for each partial contents in said range for partial contents.

18. A computer readable storage medium which stores the program according to claim 16.

13. A control method in an information encrypting apparatus for encrypting contents information including partial contents arranged in a sequence along a predetermined axis, comprising:

a root key generating step of generating root key information of said contents information;

a hierarchical structure key generating step of generating i keys of the i^th layer based on i−

1 keys at an upper i−

1^th layer and generating key information for the number of said partial contents at a terminal position, wherein said hierarchical structure key generating step generates node keys P (i,

     1) and P (i, i) at both sides by a one-way function from node keys P (i−

1,

     1) and P (i−

1, i−

1) at the upper i−

1^th layer, and a node key P (i, m) (m=2, 3, . . . , i−

1) by a one-way function which can generate the keys from any of node keys P (i−

1, m−

1) and P(i−

1, m) at the upper i−

1^th layer, where j^th node key at the i^th layer is represented as P (i, j) (j=1, 2, . . . , i−

1);

an encrypting step of encrypting each of partial contents by using key information at a terminal layer generated at said hierarchical structure key generating step; and

a storing step of storing encrypted contents information including partial contents encrypted at the encrypting step, said root key information and information for determining a boundary position for each of partial contents in a predetermined storage.

15. A computer program that functions as an information encrypting apparatus for encrypting contents information including partial contents arranged in a sequence along a predetermined axis, when read in a computer, wherein said computer program functions as:

root key generating means for generating root key information of said contents information;

hierarchical structure key generating means for generating i keys of the i^th layer based on i−

1 keys at an upper i−

1^th layer and generating key information for the number of said partial contents at a terminal position, wherein said hierarchical structure key generating means generates node keys P (i,

     1) and P (i, i) at both sides by a one-way function from node keys P (i−

1,

     1) and P (i−

1, i−

1) at the upper i−

1^th layer, and a node key P (i, m) (m=2, 3, . . . , i−

1) by a one-way function which can generate the keys from any of node keys P (i−

1, m−

1) and P(i−

1, m) at the upper i−

1^th layer, where j^th node key at the i^th layer is represented as P (i, j) (j=1, 2, . . . , i−

1);

encrypting means for encrypting each of partial contents by using key information at a terminal layer generated by said hierarchical structure key generating means; and

storing means for storing encrypted contents information including partial contents encrypted by the encrypting means, said root key information and information for determining a boundary position for each of partial contents.

17. A computer readable storage medium which stores the computer program according to claim 15.