Physically Obfuscated Circuit with Discharge Circuits for Bit Stability
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Solution Overview
Problem
Existing physically obfuscated circuits (POCs) face challenges such as poor bit stability, high susceptibility to physical attacks, and the need for error correction due to manufacturing variations and environmental factors.
Innovation Solution
The implementation of a POC circuit arrangement that utilizes extremely nonlinear electrothermal depth subthreshold relaxation processes from non-equilibrium states to limited-equilibrium states, specifically using TIE cells with discharge circuits to enhance bit stability and resistance to physical attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional POC circuits are used, then they can generate physically obfuscated circuit values, but they suffer from poor bit stability and high susceptibility to physical attacks
Solution Approach 1:
The patent changes the operating parameters of the POC circuit by introducing discharge circuits that actively control the voltage levels and timing characteristics. This modifies the electrothermal relaxation process to achieve more stable bit values while maintaining physical obfuscation, directly addressing the bit stability issue without compromising security against physical attacks
Solution Approach 2:
The discharge circuits provide feedback mechanisms that monitor and adjust the circuit state during operation. This feedback control ensures that the POC circuit maintains stable bit values by compensating for variations in manufacturing processes and environmental conditions, thereby improving reliability while preserving the inherent security properties
2Productivity
If conventional POC circuits are used, then they can generate secret keys, but they require error correction due to manufacturing variations and environmental factors
Solution Approach 1:
The discharge circuits perform preliminary action by pre-charging and pre-discharging the circuit nodes to known states before key generation begins. This preliminary conditioning ensures that the POC circuit starts from a deterministic state, eliminating the need for error correction during key generation and improving both productivity and device complexity efficiency
Solution Approach 2:
The POC circuit with discharge circuits is self-correcting by design. The discharge circuits automatically compensate for manufacturing variations and environmental factors without requiring external error correction mechanisms, allowing the circuit to generate reliable secret keys directly while maintaining high productivity and avoiding additional complexity
3Reliability
If TIE cells with discharge circuits are used, then bit stability and security are improved, but the circuit complexity increases
Solution Approach 1:
The patent segments the POC circuit into modular TIE cell units, each with its own discharge circuit. This segmentation allows the complex functionality to be distributed across multiple identical or similar modules, making the overall circuit more manageable while maintaining high bit stability and security. Each module can be independently designed and tested
Solution Approach 2:
The discharge circuits serve multiple functions: they pre-charge nodes, control timing, provide feedback, and compensate for process variations. By making these components multi-functional, the patent reduces the need for separate dedicated circuits for each function, thereby limiting the increase in overall circuit complexity while achieving improved bit stability and security
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 achieves significantly improved security against physical attacks and high reproducibility, eliminating the need for error correction, thus providing a secure and cost-effective method for generating secret keys.
Implementation Method 1
The implementation of a POC circuit arrangement that utilizes extremely nonlinear electrothermal depth subthreshold relaxation processes from non-equilibrium states to limited-equilibrium states
Implementation Method 2
At least one subcircuit of the multiple subcircuits has a discharge circuit that is connected to a connection node between two transistors of the multiple series-connected transistors of the first conductivity type for the controlled discharge of electric charge from the connection node
Data Source
AI summary
Physically obfuscated circuit including subcircuits each having: series-connected transistors of a first conductivity; a transistor of a second conductivity; wherein the transistors are connected such that the series-connected transistors, if supplied with a first reference potential at their respective control terminal, deliver a second reference potential different from the first reference potential to the control terminal of the transistor of the second conductivity; and the transistor of the second conductivity, if supplied with a second reference potential at its control terminal, delivers the first reference potential to the control terminal of each of the series-connected transistors; and a precharge circuit to precharge the subcircuit to a first state in which the potential at the control terminal of the transistor of the second conductivity is different from the second reference potential and the potential at the control terminal of each of the series-connected transistors is different from the first reference potential.