Cell Circuit Biasing to Tune PUF and RNG Consistency

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Solution Overview

Problem

The contamination of electronic component supply chains by counterfeit hardware devices poses a significant risk due to vulnerabilities in encryption keys stored in fuses, which can be prone to visual and electrical probing attacks, and insider threats, necessitating improved device authentication methods.

Innovation Solution

The implementation of techniques to change the consistency behavior of cell circuits through stress mechanisms such as hot carrier injection (HCI) and biasing, allowing for the transformation of cell circuits between physically unclonable function (PUF) and random number generation (RNG) behaviors, enhancing authentication security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If encryption keys are stored in fuses, then device authentication is provided, but the fuses are prone to visual and electrical probing attacks and insider threats

Engineering Contradiction:

Improvedevice authentication securityVSAvoidvulnerability to probing attacks

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the inherent physical variations in transistor manufacturing, which traditionally cause circuit inconsistency, into a beneficial security feature. By exploiting these variations in PUF circuits, the system generates unique cryptographic keys that are difficult to clone or predict, thereby transforming manufacturing imperfections into a defense against probing attacks and insider threats.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent dynamically changes the operational parameters of cell circuits by applying stress conditions such as hot carrier injection. This allows the same hardware circuit to exhibit different behavioral characteristics under different stress levels, enabling the system to switch between PUF mode (for secure key generation) and RNG mode (for random number generation), thereby enhancing security against static analysis and probing attacks.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If cell circuits are stressed to change behavior consistency, then authentication security is enhanced, but additional circuitry and control mechanisms are required

Engineering Contradiction:

Improveauthentication securityVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent designs cell circuits that can perform multiple functions depending on the applied stress conditions. The same basic circuit structure can operate as a PUF circuit for cryptographic key generation or as an RNG circuit for random number generation, simply by changing the stress conditions. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby limiting the increase in overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If PUF behavior consistency is increased for security, then device authentication is strengthened, but the ability to generate random numbers is reduced

Engineering Contradiction:

Improvedevice authenticationVSAvoidbehavioral flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic control over cell circuit behavior by applying different stress conditions in real-time. The system can switch between PUF mode (with high consistency for authentication) and RNG mode (with high randomness for random number generation) based on operational requirements. This dynamic adaptability allows the same hardware to provide both strong authentication security and versatile functionality without compromising either aspect.

Inventive Principle:

Principle #15Dynamics

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 strengthens device authentication by increasing the consistency of PUF behavior or randomness of RNG behavior, effectively counteracting counterfeiting and insider threats, thereby enhancing the security of electronic devices.

Implementation Method 1

techniques to change the consistency behavior of cell circuits through stress mechanisms such as hot carrier injection (HCI)

Methodology Applied

Scientific EffectHot carrier injection:

Implementation Method 2

stress mechanisms such as hot carrier injection (HCI) and biasing

Methodology Applied

Scientific EffectBiasing:

Data Source

PatentUS10825511B2Device, system, and method to change a consistency of behavior by a cell circuit

Publication Date: 2020.11.03 INTEL CORP

AI summary

Techniques and mechanisms for changing a consistency with which a cell circuit (“cell”) settles into a given state. In one embodiment, a cell settles into a preferred state based on a relative polarity between respective voltages of a first rail and a second rail. Based on the preferred state, a hot carrier injection (HCI) stress is applied to change a likelihood of the cell settling into the preferred state. Applying the HCI stress includes driving off-currents of two PMOS transistors of the cell while the relative polarity is reversed. In another embodiment, a cell array comprises multiple cells which are each classified as being a respective one of a physically unclonable function (PUF) type or a random number generator (RNG) type. A cell is selected for biasing, and a stress is applied, based on each of: that cell's preferred state, that cell's classification, and another cell's classification.