Non-Volatile Memory PUF Key Freezing Against ReRAM Bit Drift
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Solution Overview
Problem
Existing technologies face challenges in generating and storing physical unclonable function (PUF) keys with high reliability and security, particularly due to high bit error rates caused by resistance drift in resistive random access memory (ReRAM) and other non-volatile memory technologies.
Innovation Solution
The proposed solution involves using a physical unclonable function (PUF) to generate keys and then freezing these keys in an unchangeable form using internal or external logic, ensuring that the PUF keys are stored in a stable and secure manner within non-volatile memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ReRAM-based PUF is used to generate keys, then key generation capability is improved, but bit error rate increases due to resistance drift
Solution Approach 1:
The patent applies preliminary action by freezing the PUF key data in non-volatile memory cells immediately after generation, preventing subsequent changes due to resistance drift. The system performs the freezing operation as a preliminary step before any potential drift occurs, ensuring long-term stability of the generated keys.
Solution Approach 2:
The patent introduces an intermediary mechanism by using non-volatile memory cells as a stable storage medium between the ReRAM PUF generation process and the final key usage. This intermediary storage layer isolates the generated keys from the drift effects, providing a stable reference point for authentication and encryption operations.
2Duration of action of stationary object
If PUF keys are stored in non-volatile memory, then data persistence is improved, but data security deteriorates due to potential changes and corruption
Solution Approach 1:
The patent extracts the PUF key data from the mutable ReRAM structure and stores it in separate non-volatile memory cells. This separation allows the system to maintain persistent storage while protecting the key data from corruption, as the frozen keys in non-volatile memory cannot be accidentally modified.
Solution Approach 2:
The system performs a preliminary freezing operation that locks the key data in non-volatile memory cells, preventing any subsequent changes. This preliminary action ensures that once the keys are stored, they remain immutable, thereby maintaining both persistence and security over the device lifetime.
3Ease of manufacture
If resistance drift is allowed in memory cells, then manufacturing simplicity is improved, but measurement precision deteriorates due to bit errors
Solution Approach 1:
The patent introduces non-volatile memory cells as an intermediary storage layer that captures the PUF key data at a specific point in time. This intermediary structure provides a stable, drift-free reference that maintains manufacturing simplicity while eliminating measurement precision issues caused by resistance drift.
Data Source
AI summary
A device which can be implemented on a single packaged integrated circuit or a multichip module comprises a plurality of non-volatile memory cells, and logic to use a physical unclonable function to produce a key and to store the key in a set of non-volatile memory cells in the plurality of non-volatile memory cells. The physical unclonable function can use entropy derived from non-volatile memory cells in the plurality of non-volatile memory cells to produce a key. Logic is described to disable changes to data in the set of non-volatile memory cells, and thereby freeze the key after it is stored in the set.