Register Shield Circuitry for Selective Access Control
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Solution Overview
Problem
Existing semiconductor devices face challenges in selectively disabling or preventing undesired operation features without redesigning the circuit, especially when silicon is already in production.
Innovation Solution
The implementation of selectively-activateable register shield circuitry between the interface and the set of registers, which intercepts requests, determines prohibited access, and prevents access to prohibited register portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If register shield circuitry is added to selectively block access to certain register portions, then security and access control are improved, but device complexity increases
Solution Approach 1:
A register shield circuit is introduced as an intermediary component between the interface and the register portions. This circuit includes a shield enable input that controls whether access to specific register portions is blocked or allowed, acting as a mediator that selectively permits or prevents data flow without requiring complete redesign of the register interface architecture.
Solution Approach 2:
The register interface is segmented into protected and unprotected portions through the register shield circuit. The shield circuit can selectively block access to specific register portions (e.g., R[7:4]) while allowing access to other portions (e.g., R[3:0]), enabling granular security control at the bit-level or field-level within registers rather than protecting entire registers as a unit.
2Reliability
If physical prevention of register instantiation is implemented, then undesired operation features are prevented, but adaptability and post-production modification capability deteriorate
Solution Approach 1:
The register shield circuit introduces dynamic control over register access through the shield enable input. Unlike static physical prevention methods where registers are completely removed or disabled at fabrication time, this circuit allows the protection state to be dynamically changed after silicon production by modifying the shield enable signal, enabling adaptability and post-production modification of security configurations.
Solution Approach 2:
The system changes the operational parameter of register access control from a fixed physical state to a controllable logical state. By using the shield enable input to control the activation state of the shield circuit, the system can transition between protected and unprotected states without physical redesign, allowing parameter-based control of feature availability rather than hard-coded physical prevention.
Data Source
AI summary
A semiconductor device comprises one or more registers having digital signals stored therein. The semiconductor device is configured for communication with one or more external devices and such communication may involve requests for access to portions of these register or registers. Register shield circuitry is provided comprising access detection circuitry configured to detect requests for access to these register portions in communication with the external device or devices. The register shield circuitry is configured to be selectively activated in a register shield mode to shield these register portions from undesired requests for access. When activated in the register shield mode, the register shield circuitry prevents access to these register portions in response to requests for access detected by the access detection circuitry.