Carbon Nanotube Entropy Source for Compact Cryptographic Key Generation

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Solution Overview

Problem

Existing cryptographic mechanisms for generating strong cryptographic keys in microelectronic devices face challenges due to size, weight, and energy consumption constraints, making traditional physical entropy sources unsuitable for these devices.

Innovation Solution

A carbon nanotube-based field-effect transistor (CNT-FET) is used as a physical entropy source to generate random current outputs, which are then converted into random voltage values for cryptographic key generation, offering a compact, energy-efficient solution integrated into microelectronic circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional physical entropy sources are used for cryptographic key generation, then security strength is improved, but device size and energy consumption increase making them unsuitable for microelectronic devices

Engineering Contradiction:

Improvecryptographic key strengthVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the physical parameters of the entropy source by using carbon nanotubes with specific structural properties (diameter, length, chirality) that enable random current generation at the nanoscale. This allows traditional entropy source functionality to be achieved with dramatically reduced energy consumption and device size, resolving the contradiction between security strength and energy efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional mechanical or macroscopic physical entropy sources with a nanoscale electronic system based on carbon nanotube field-effect transistors. The random current generation mechanism at the nanoscale substitutes for traditional entropy sources, achieving the same cryptographic security function with minimal energy consumption and compact form factor

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If traditional physical entropy sources are used for cryptographic key generation, then security strength is improved, but device complexity and size increase

Engineering Contradiction:

Improvecryptographic key strengthVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the spatial parameters by transitioning from macroscopic entropy sources to nanoscale carbon nanotube structures. The field-effect transistor configuration with carbon nanotube channel enables random current generation in a compact footprint, resolving the contradiction between security strength and device size

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes traditional complex physical entropy source mechanisms with a simplified nanoscale electronic system. The carbon nanotube FET leverages quantum and thermal effects at the nanoscale to generate random currents, eliminating the need for complex mechanical or macroscopic entropy generation apparatus

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Use of energy by moving object

If carbon nanotube structure is used to generate random current, then energy efficiency and compactness are improved, but integration with existing cryptographic circuits requires additional conversion circuits

Engineering Contradiction:

Improveenergy efficiencyVSAvoidcircuit integration complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent merges the carbon nanotube random current source with the cryptographic circuit by integrating current-to-voltage conversion and random bit generation functions directly into the cryptographic processing path. This consolidation reduces the number of separate components and simplifies the overall system architecture, resolving the contradiction between energy efficiency and circuit integration complexity

Inventive Principle:

Principle #5Merging (Combining)

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 CNT-based solution provides a secure, compact, and energy-efficient means for generating cryptographic keys, protecting the secrecy of random numbers by integrating the entropy source within the chip, thus preventing reverse engineering and ensuring the integrity of the generated keys.

Implementation Method 1

carbon nanotube generates a random current output due to sensitivity of the carbon nanotube to trap charges absorbed by the dielectric near or on a surface of the carbon nanotube

Methodology Applied

Scientific EffectTrap charge absorption: Absorption (physical)

Data Source

PatentUS10944556B2Carbon nanotube physical entropy source

Publication Date: 2021.03.09 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A random value generator is provided that comprises a carbon nanotube structure that generates a random output current in response to a voltage input. The random value generator includes a random value output circuit coupled to the carbon nanotube structure that receives the random output current from the carbon nanotube structure and generates a random output value based on the received random output current from the carbon nanotube structure.