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Data encryption and deciphering method, appts. and program

An encryption method and encrypted technology, applied in the field of encryption or decryption, can solve the problem of time-consuming and other problems

Inactive Publication Date: 2004-03-10
DENSO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It will take more time for the analysis before decryption

Method used

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  • Data encryption and deciphering method, appts. and program
  • Data encryption and deciphering method, appts. and program
  • Data encryption and deciphering method, appts. and program

Examples

Experimental program
Comparison scheme
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Embodiment Construction

[0013] Detailed description of the preferred embodiment

[0014] The data encryption device 1 and the data decryption device 2 of the embodiment of the present invention are Figure 1A , 1B Indicated. The data encryption device 1 includes an input module 11 for inputting data from the outside, an encryption module 12 for encrypting input data, and an output module 13 for outputting encrypted data. In this embodiment, the plaintext map data is stored in the data memory 3 and encrypted by the data encryption device 1, and then stored in the storage medium 5, such as DVD-ROM, CD-ROM or HDD. The storage medium 5 storing the encrypted map data is distributed to the user.

[0015] In contrast, the data decryption device 2 includes an input module 21 for inputting data from the outside, a decryption module 22 for decrypting the input data, and an output module 23 for outputting the decrypted data. In this embodiment, the encrypted map data is stored in the storage medium 5 and is ...

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PUM

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Abstract

Encryption is executed with respect to an encryption target unit based on an encryption ratio with maintaining the same data length both prior to and subsequent to the encryption process. In Pattern 1, one third from the encryption target unit is encrypted, while two thirds (the rest) of the encryption target unit are not encrypted. In Pattern 2, three sub-patterns P1, P2, P3 that have different encryption ratios are applied. The sub-patterns P1, P2, P3 have the encryption ratios of 50%, 25%, and 75%, respectively. In Pattern 3, three sub-patterns P11, P12, P13 that have different encryption starting points in addition to the different encryption ratios are applied. The sub-patterns P11, P12, P13 encrypt based on encryption ratios of 50%, 25%, and 75% from 25%, 50%, and 0% subsequent to the beginning of the unit.

Description

technical field [0001] The present invention relates to an encryption or decryption technique capable of shortening the time of decryption processing and restricting illegal duplication. Background technique [0002] For example, a map display device, a routing assistance device, or a navigator uses map data to perform some processing. The map data used in the device is stored in a storage medium such as DVD-ROM, CD-ROM or HDD, and provided to the user. [0003] Map data are stored in encrypted form to prevent them from being copied illegally. However, encrypting all map data results in the need for a large memory and long data processing time for decryption. This solution is impractical. Japanese Patent JP-A-2000-341266 describes a technique for a data block including header information and content data requiring protection. Here, the header information is encrypted by a complex encryption method, which takes a relatively long time for decryption. At the same time, the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B20/10G06F3/06G06F12/14G09C1/00H04K1/00H04L9/00H04L9/06
CPCH04L9/00H04L2209/605H04L9/06
Inventor 藤本英俊木村匡宏
Owner DENSO CORP