Volatile OTS Switch Matrix for Secure Authentication

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Solution Overview

Problem

Existing solutions for secure authentication and data storage, such as PUF technology using OxRAM matrices, lack optimal security as they can be compromised by knowing the operating principles and reading voltages, leading to potential code exposure or modification.

Innovation Solution

A matrix of volatile OTS switches with a unique current-voltage characteristic, where switches are initialized by a forming voltage and read using a carefully chosen voltage between the threshold and forming voltage ranges, ensuring high resistive states without code modification, thus enhancing security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If OxRAM matrices are used for PUF technology, then authentication security is provided, but the security can be compromised by knowing operating principles and reading voltages

Engineering Contradiction:
Improveauthentication securityVSAvoidcode exposure risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the electrical parameters of the switches by using OTS (Ovonic Threshold Switching) material with distinct threshold voltage and forming voltage characteristics. This creates a voltage window for reading that prevents unintended forming, thereby securing the code against exposure while maintaining authentication functionality

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses volatile OTS switches that lose their state when power is removed, creating a temporary, non-persistent storage mechanism. This volatility ensures that the code cannot be easily extracted or cloned, enhancing security while maintaining the authentication function

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Loss of information

If reading voltage is applied to OTS switches, then the code can be read, but the voltage must be precisely chosen to avoid modifying the code

Engineering Contradiction:
Improvecode retrievalVSAvoidvoltage control precision
Core Design Contradiction:
Loss of informationVSManufacturing precision

Solution Approach 1:

The patent performs preliminary initialization of the OTS switches during manufacturing or before use. This preliminary action establishes the switches in a known state and creates the voltage window characteristics needed for secure reading without modification, reducing the precision burden during actual code retrieval operations

Inventive Principle:
Principle #10Preliminary action

3Reliability

If OTS switches are initialized by forming voltage, then the switches enter low resistive state, but applying voltage higher than forming voltage can break the code

Engineering Contradiction:
Improveswitch state stabilityVSAvoidcode destruction risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary voltage window between the threshold voltage and forming voltage. This window acts as a safe reading zone where the switches can be queried without triggering the forming process that would modify or break the code, thereby maintaining both state stability and code integrity

Inventive Principle:
Principle #24Intermediary (Mediator)

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

The matrix provides increased security by making it difficult to access the code without destroying it, as the reading voltage must be precisely chosen, and the use of OTS switches ensures a high ratio between ON and OFF states, facilitating secure message representation and retrieval.

Implementation Method 1

each volatile switch comprising an active layer made of an OTS material

Methodology Applied
Scientific EffectOvonic Threshold Switching:

Implementation Method 2

The transition from the 'HRS' state to the 'LRS' state is governed by the formation and rupture of a conductive filament between the two electrodes

Methodology Applied
Scientific EffectConductive filament formation and rupture:

Implementation Method 3

the use of OTS switches ensures a high ratio between ON and OFF states, facilitating secure message representation and retrieval

Methodology Applied
Scientific EffectResistive state differentiation: Electrical Resistance

Data Source

PatentEP4030432B1Array of basic switches forming a message, associated writing and reading methods
Publication Date: 2024.11.13 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP4030432B1 patent drawingFigure 1~2
  • EP4030432B1 patent drawingFigure 3~4
  • EP4030432B1 patent drawingFigure 5~6

AI summary

The invention relates to a matrix comprising a plurality of volatile switches, each of said volatile switches having an active layer made of an OTS material, the plurality of volatile switches being divided into two groups so as to form a message, - each of the volatile switches of the first group having been previously initialized by means of an initialization voltage, - none of the volatile switches of the second group having been previously initialized, - said message being formed by the initialized or uninitialized states of each of the switches of the matrix.