Integrated Circuit Memory Locking Mechanism
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Solution Overview
Problem
Existing methods for protecting integrated circuits with sensitive data, such as using fuses that can be reopened via FIB techniques, are inadequate as they can be reversed, compromising data security.
Innovation Solution
An integrated circuit with a memory device featuring a non-volatile memory plane divided into areas, where a locking mechanism is implemented to irreversibly lock access to sensitive data upon detection of a specific locking content, preventing unauthorized access or data extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuses are used to lock access to sensitive data, then data protection is improved, but the locking mechanism can be reversed using FIB techniques, compromising security
Solution Approach 1:
The patent changes the physical state of memory cells from volatile to non-volatile by programming floating-gate cells. This parameter change makes the stored data permanent and不可逆 (irreversible), as the floating-gate structure physically traps charge that cannot be easily removed, thereby preventing reversal of the locking mechanism while maintaining data protection.
Solution Approach 2:
The patent employs a disposable locking mechanism where the memory plane is designed to be written-only after initial programming. The locking content is embedded during manufacturing and cannot be altered or erased, effectively making the locking mechanism single-use and irreversible, thus preventing any future attempts to reverse the security measure.
2Reliability
If the memory plane is made non-observable in read mode from outside, then data security is improved, but access to sensitive data becomes more restricted
Solution Approach 1:
The patent introduces an intermediary controller that mediates between external users and the non-observable memory plane. The controller can selectively translate internal memory addresses to external interfaces, allowing authorized read access to sensitive data while maintaining the non-observable nature of the memory plane itself. This intermediary layer enables controlled access without compromising security.
Solution Approach 2:
The patent segments the memory access functionality into two distinct parts: the non-observable memory plane that stores sensitive data and the observable interface that provides controlled access. By separating the storage function (non-observable) from the access function (observable and controllable), the system maintains both security and ease of operation for authorized users.
3Reliability
If write access to the memory device is locked, then protection against unauthorized modification is improved, but the ability to perform tests before locking is reduced
Solution Approach 1:
The patent performs all necessary testing and programming actions before applying the final locking mechanism. The memory plane can be written, tested, and verified in an unlocked state during manufacturing and development phases. Once testing is complete and the data is verified, the locking mechanism is applied to prevent any future modifications. This preliminary action sequence resolves the contradiction by enabling testing before locking while maintaining protection afterward.
Data Source
AI summary
An integrated circuit comprises a memory device including a memory plane having non-volatile memory cells and being non-observable in read mode from outside the memory device, a controller, internal to the memory device, configured to detect the memorized content of the memory plane, and when the memorized content contains locking content, automatically lock any access to the memory plane from outside the memory device, the integrated circuit then being in a locked status, and authorize delivery outside the memory device of at least one sensitive datum stored in the memory plane.