Semiconductor Entropy Source Anti-Reverse Engineering Mechanism
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Solution Overview
Problem
Existing semiconductor devices face challenges in preventing reverse engineering of physical unclonable function bit values outputted from entropy sources, which are crucial for device security, as these values are inherently unique and stable but can be vulnerable to unauthorized analysis and reconstruction.
Innovation Solution
The semiconductor device incorporates an entropy source with bitcells arranged in bitline columns and wordline rows, where a damage-inducing voltage higher than the operating voltage is applied to selectively damage or alter the bitcells, inducing time-dependent dielectric breakdown to create a conductive path and render the original intrinsic properties unusable for reverse engineering, thus preventing unauthorized access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the physical unclonable function bit values are outputted from the entropy source without storage or programming, then the generation of unique device secret is simplified and faster, but the security against reverse engineering is weakened
Solution Approach 1:
The patent applies preliminary action by implementing a damage mechanism that can be activated before reverse engineering attempts succeed. The entropy source includes a mechanism to selectively damage bitcells or alter their intrinsic properties in anticipation of unauthorized analysis, thereby preventing reverse engineering while maintaining the simplicity of the entropy generation process
Solution Approach 2:
The patent converts the potential harm of exposed intrinsic properties into a benefit by implementing a selective damage mechanism. When damage is applied to bitcells, their intrinsic properties are altered in a controlled manner that prevents reverse engineering while maintaining the security function, effectively turning a vulnerability into a protective feature
2Reliability
If a damage mechanism is added to prevent reverse engineering, then security against unauthorized analysis is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the damage mechanism to serve multiple functions: it can selectively damage bitcells, alter intrinsic properties, and prevent reverse engineering all through a unified mechanism that integrates with the existing entropy source structure, thereby adding security without proportionally increasing complexity
Solution Approach 2:
The patent applies local quality by implementing selective damage to specific bitcells or portions of the entropy source rather than destroying the entire device. This allows the damage mechanism to target only the necessary components for preventing reverse engineering while preserving other functional elements, thereby minimizing the increase in overall device complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively renders it practically impossible to reverse engineer the physical unclonable function bit values, ensuring the security of the semiconductor device by making the unique device secret unattainable, thereby maintaining the integrity of the security protocol.
Implementation Method 1
inducing time delayed dielectric breakdown between the gate terminals and other terminals of the two or more respective bitcells to create a conductive path for a leakage current
Data Source
AI summary
A semiconductor device is configured to implement a security protocol. The semiconductor device includes an entropy source that includes a plurality of bitcells. The entropy source is configured to output a sequence of physical unclonable function bit values based on intrinsic properties of the plurality of bitcells to generate a unique device secret for the security protocol, and selectively damage at least a portion of the plurality of bitcells to prevent reverse engineering the sequence of physical unclonable function bit values.