Memory data protecting device and LSI for IC card

Abstract

The present invention provides a data protecting device for the storing device, which sets illegal visiting used area in the memory space, and allocates physical addresses to the illegal visiting used area. In the visiting authority judging part and the visiting judging circuit, it judges the visiting to the safe data which is to be executed by the CPU is normal visiting or illegal visiting. When the visiting is judged to be illegal visiting, it modifies the logical address mapping of the safe data which is to be visited to the physical address of the illegal visiting used area. Afterwards, it does data treatment to the illegal visiting used area when the mapping is modified. Therefore, when illegal visiting happens, the location of the important area where the safety data is stored is not identified, and thereby it can protect the safety data.

Description

technical field [0001] The present invention relates to a memory data protection device and an IC card LSI for improving security functions by controlling access to a memory storing security data such as an LSI used in an IC card. Background technique [0002] LSIs for IC cards equipped with memories storing security data are used in electronic train tickets, credit cards, etc. [0003] ROM, SRAM, and nonvolatile memory are usually installed in LSIs for IC cards. Among them, ROM stores application programs and control programs, SRAM temporarily stores data generated during operation, and nonvolatile memory retains data even when the power is turned off. These memories store data such as personal privacy information and financial information, so ensuring security is an important issue. [0004] Conventionally, as a semiconductor integrated circuit with improved security functions, there is, for example, the technology described in Japanese Patent Application Laid-Open No. 20...

AI Technical Summary

Problems solved by technology

[0005] However, in the technology described in the above-mentioned Japanese Patent Application Laid-Open No. 2005-25340, since the generation of the access control signal is prohibited so that the memory cannot be accessed, when illegal access such as illegal reading or writing occurs, the data stored in the Although the data in the memory cannot be read or written, there is a possibility that the protected storage area is judged to be an important data area storing security data, and the location of the important data area may be identified

When the location of the important data area is identified, the security data stored in the memory can be tampered with by probing the memory, and the LSI can be made to act illegally and analyze it, so it cannot be said that the data is guaranteed to be in the security status

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