Coupling Controller for Flash Interface Security
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Solution Overview
Problem
Existing security systems for information processing apparatuses are vulnerable to unauthorized access through external interfaces, which can lead to tampering or destruction of secret information, especially when high-skilled individuals manipulate signals at these interfaces.
Innovation Solution
A functional device with a coupling controller that physically manages external and internal interfaces, using a coupling circuit with a fuse and register to ensure only authorized access by coupling or decoupling the interfaces based on successful certification processing, thereby preventing unauthorized access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an external interface is provided to enable external access, then the ease of operation is improved, but the security against unauthorized access deteriorates
Solution Approach 1:
The patent applies preliminary action by performing certification processing before enabling the external interface to be conducted with the functional component. The control device executes certification processing in advance, and only after successful certification does it physically conduct the external interface with the functional component, thereby preventing unauthorized access before it can occur
2Ease of operation
If the external interface is always connected to the functional component, then the ease of operation is improved, but the security against tampering deteriorates
Solution Approach 1:
The patent applies dynamics by making the connection state of the external interface changeable based on certification results. The external interface is dynamically conducted or non-conducted with the functional component depending on whether certification processing succeeds, allowing the system to adapt its security state rather than maintaining a fixed connection
3Reliability
If certification processing is required before interface connection, then the security is improved, but the productivity deteriorates due to additional processing time
Solution Approach 1:
The patent applies preliminary action by having the control device execute certification processing in advance before the external interface is needed for operational access. This preliminary certification ensures that when the interface is subsequently conducted, the security verification has already been completed, streamlining the access process
Data Source
AI summary
A functional device which surely prevents tampering performed through an external interface in the functional device comprising an external interface which is accessible to an internal functional component is provided. In the functional device, a coupling controller is provided between an external Flash terminal which is an external interface and an internal Flash memory. The coupling controller physically blocks between the external Flash terminal and the internal Flash memory after a Fuse is disconnected except for a case where a certification result in a REG maintains validity. The certification result is validated only while current is carried.