Dissolvable Conductive Paths in ReRAM PUFs
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Solution Overview
Problem
Conventional Physically Unclonable Functions (PUFs) based on Resistive Random Access Memory (ReRAM) cells are vulnerable to crypto-analytic techniques and side-channel attacks, and they have high energy consumption and large circuit footprints, making them susceptible to extraction and analysis.
Innovation Solution
The method involves generating a physically unclonable function response by forming temporary dissolvable conductive paths in dielectric material between electrodes of ReRAM cells, measuring resistances, and assigning parameter values to generate a unique data stream, which can be used for authentication, utilizing a system with a secure processor to apply electric fields and determine resistance thresholds to create a ternary data stream for enhanced security and low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ReRAM-based PUFs are used, then they can provide authentication functionality, but they are vulnerable to crypto-analytic techniques and side-channel attacks
Solution Approach 1:
The patent segments the conductive path into multiple discrete filament segments separated by dielectric regions. Each segment can be independently controlled, allowing the system to break down the continuous conductive path into manageable units that can be individually manipulated for enhanced security against extraction attacks
Solution Approach 2:
The patent changes the physical state of the conductive paths by forming and dissolving filaments through controlled electric field application. The resistance values are dynamically adjusted by forming temporary conductive paths during measurement and then dissolving them, creating time-varying resistance parameters that prevent static analysis and side-channel attacks
2Reliability
If conventional ReRAM-based PUFs are used, then they can generate challenge-response pairs, but they have high energy consumption
Solution Approach 1:
The patent employs periodic formation and dissolution of conductive filaments during challenge-response generation. The temporary conductive paths are formed only when needed for measurement and then dissolved, creating a periodic on-demand operation mode that reduces overall energy consumption compared to continuously maintained conductive paths
Solution Approach 2:
The patent discards the temporary conductive paths after measurement by applying reverse polarity voltage to dissolve the filaments. This discarding mechanism allows the system to recover energy and prevents the need for continuous power supply to maintain conductive states, significantly reducing standby power consumption
3Reliability
If conventional ReRAM-based PUFs are used, then they can provide unique device identification, but they have large circuit footprints
Solution Approach 1:
The patent implements a nested structure where multiple filament segments are arranged in series within a single ReRAM cell, and multiple cells are organized into arrays. This nesting allows the system to pack more functional elements into a smaller physical footprint while maintaining device uniqueness through the combined resistance characteristics of nested segments
Solution Approach 2:
The patent transitions from two-dimensional planar conductive paths to three-dimensional vertically stacked filament segments within the dielectric layer. This dimensional change allows the system to increase the number of measurable resistance elements without proportionally increasing the lateral circuit footprint, achieving higher uniqueness density
4Reliability
If temporary dissolvable conductive paths are formed, then security is enhanced against extraction, but the process complexity increases
Solution Approach 1:
The patent employs self-service mechanisms where the same ReRAM cell structure that stores data also forms the temporary conductive paths for measurement. The dielectric material and electrode configuration that define the cell's memory function are reused to create the measurement pathways, eliminating the need for separate dedicated measurement structures and reducing overall process 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 enhances the security and reliability of ReRAM-based PUFs by reducing error rates in challenge-response pairs and lowering power consumption, making them resistant to crypto-analytic techniques and physical attacks, while maintaining small circuit size.
Implementation Method 1
exposing each cell of a random access memory array to an electric field to form temporary dissolvable conductive paths in dielectric material between electrodes
Data Source
AI summary
The generation of “fingerprints”, also called challenge-response pairs (CRPs) of Physically Unclonable Functions (PUFs), can often stress electronic components, leaving behind traces that can be exploited by crypto-analysts. A non-intrusive method to generate CRPs based on Resistive RAMs may instead be used, which does not disturb the memory cells. The injection of small electric currents (magnitude of nanoAmperes) in each cell causes the resistance of each cell to drop abruptly by several orders of magnitudes through the formation of temporary conductive paths in each cell. A repeated injection of currents into the same cell, results in an almost identical effect in resistance drop for a single cell. However, due to the small physical variations which occur during manufacturing, the cells are significantly different from each other, in such a way that a group of cells can be used as a basis for PUF authentication.