Method of and system for encrypting digital data, method of and apparatus for reproducing digital data, and computer product

• US 20020168068A1
• Filed: 04/30/2002
• Published: 11/14/2002
• Est. Priority Date: 05/11/2001
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Nasu, Masami
• Granted Patent: US 7,330,980 B2
• Time in Patent Office: Days
• US Class Current: 380/201
• CPC Class Codes: H04N 2005/91364 the video signal being scrambled
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

There is provided an input unit which reads copyright digital data stored in a recording medium such as a CD-ROM, an operation unit which performs encryption of digital data based on an encryption algorithm from a plurality of encryption algorithms. A file unit outputs the encrypted digital data and an index value and the encryption operation equation generation parameter into one file. A reproducing apparatus obtains an encryption operation equation from the index value and the encryption operation equation generation parameter in this same file and reproduces the encrypted digital data.

Claims

1. A digital data encryption system comprising:

an operation unit which receives digital data and encrypts the digital data in accordance with a predetermined encryption algorithm and an encryption operation equation determined based on an encryption operation equation generation parameter; and

a file unit which generates a file containing the encrypted digital data, an index value capable univocally of determining the encryption algorithm, and the encryption operation equation generation parameter used for encryption of the digital data.

2. The digital data encryption system according to claim 1, further comprising a setting unit which registers a plurality of encryption algorithms;

and selecting unit which selects an encryption algorithm registered in the setting unit as the predetermined encryption algorithm,

wherein the operation unit encrypts the digital data based on the predetermined encryption algorithm.

3. The digital data encryption system according to claim 1, wherein

the operation unit selects the encryption algorithm and the encryption operation equation generation parameter used for actual encryption from a plurality of encryption algorithms and a plurality of encryption operation equation generation parameters prepared in advance, respectively, and conducts the encryption processing using the selected encryption algorithm and the selected encryption operation equation generation parameter.

4. The digital data encryption system according to claim 1, wherein

the operation unit can detect illegal manipulation of the digital data by executing an embedding encryption processing of embedding a specific data manipulation detection code in an arbitrary location of the digital data based on the encryption algorithm.

5. The digital data encryption system according to claim 1, wherein

the file unit changes the encrypted digital data so as not to easily specify locations in which the index value of the encryption algorithm and the encryption operation equation generation parameter which are stored in the same file as the file of the encrypted digital data, are described.

6. A digital data reproducing apparatus which decodes and reproduces copyright digital data from encrypted digital data generated by a digital data encryption system, the digital data encryption system including

an operation unit which receives digital data and encrypts the digital data in accordance with a predetermined encryption algorithm and an encryption operation equation determined based on an encryption operation equation generation parameter;

and

a file unit which generates a file containing the encrypted digital data, an index value capable univocally of determining the encryption algorithm, and the encryption operation equation generation parameter used for encryption of the digital data,

the digital data reproducing apparatus comprising;

a read unit which fetches the encrypted digital data from the file;

an operation unit which determines an index value of an encryption algorithm and an encryption operation equation based on the encryption operation equation generation parameter in the file, and decodes the encrypted digital data in accordance with the encryption operation equation to obtain decoded digital data; and

a reproducing unit which reproduces and the decoded digital data.

7. The digital data reproducing apparatus according to claim 6, wherein

the operation unit determines whether the encrypted digital data is manipulated based on whether a specific data manipulation detection code embedded in an arbitrary location of the encrypted digital data is detected, and if the operation unit determines that the encrypted digital data is manipulated, the encrypted digital data is not reproduced.

8. A digital data encryption method comprising:

receiving digital data and encrypting the digital data in accordance with a predetermined encryption algorithm and an encryption operation equation determined based on an encryption operation equation generation parameter; and

generating a file containing the encrypted digital data, an index value capable univocally of determining the encryption algorithm, and the encryption operation equation generation parameter used for encryption of the digital data.

9. The digital data encryption method according to claim 8, wherein

at the step of encryption of digital data, the encryption algorithm and the encryption operation equation generation parameter used for actual encryption are selected from a plurality of encryption algorithms and a plurality of encryption operation equation generation parameters prepared in advance, respectively, and the encryption of the digital data is conducted using the selected encryption algorithm and the selected encryption operation equation generation parameter.

10. The digital data encryption method according to claim 8, wherein

at the step of encryption of digital data, illegal manipulation of the digital data can be detected by executing an embedding encryption processing of embedding a specific data manipulation detection code in an arbitrary location of the digital data based on the encryption algorithm.

11. The digital data encryption method according to claim 8, wherein

at the step of encryption of digital data, the encrypted digital data is changed so as not to easily specify locations in which the index value of the encryption algorithm and the encryption operation equation generation parameter stored in the same file as the file of the encrypted digital data, are described.

13. The digital data reproducing method according to claim 12, wherein

at the step of determined the index value, it is determined whether the encrypted digital data is manipulated based on whether a specific data manipulation detection code embedded in an arbitrary location of the encrypted digital data is detected, and if it is determined that the encrypted digital data is manipulated, the encrypted digital data is not reproduced.

12. A digital data reproducing method for decoding and reproducing copyright digital data from encrypted digital data generated by a digital data encryption method, the digital data encryption method including

receiving digital data and encrypting the digital data in accordance with a predetermined encryption algorithm and an encryption operation equation determined based on an encryption operation equation generation parameter;

and

generating a file containing the encrypted digital data, an index value capable univocally of determining the encryption algorithm, and the encryption operation equation generation parameter used for encryption of the digital data,

the digital data reproducing method comprising;

fetching the encrypted digital data from the file;

determining an index value of an encryption algorithm and an encryption operation equation based on the encryption operation equation generation parameter in the file, and decoding the encrypted digital data in accordance with the encryption operation equation to obtain decoded digital data; and

reproducing the decoded digital data.

14. A computer program containing instructions which when executed on a computer causes the computer to realize a digital data encryption method including

receiving digital data;

encrypting the digital data in accordance with a predetermined encryption algorithm and an encryption operation equation determined based on an encryption operation equation generation parameter; and

generating a file containing the encrypted digital data, an index value capable univocally of determining the encryption algorithm, and the encryption operation equation generation parameter used for encryption of the digital data.

15. A computer program containing instructions which when executed on a computer causes the computer to realize a digital data encryption method and a digital data reproducing method,

the digital data encryption method including

receiving digital data;

encrypting the digital data in accordance with a predetermined encryption algorithm and an encryption operation equation determined based on an encryption operation equation generation parameter;

generating a file containing the encrypted digital data, an index value capable univocally of determining the encryption algorithm, and the encryption operation equation generation parameter used for encryption of the digital data,

the digital data reproducing method including

fetching the encrypted digital data from the file;

determining an index value of an encryption algorithm and an encryption operation equation based on the encryption operation equation generation parameter in the file, and decoding the encrypted digital data in accordance with the encryption operation equation to obtain decoded digital data; and

reproducing the decoded digital data.