Charge Retention Circuit Authentication via Discharge Time

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Solution Overview

Problem

Existing authentication methods for products, such as ink cartridges, are vulnerable to counterfeiting as they rely on secret keys that can be compromised, leading to non-authentic products being recognized as authentic by devices.

Innovation Solution

A method involving a host device that initializes and controls a charge retention circuit in a slave device, determining authenticity by comparing the discharge time of the circuit with an expected duration, and controlling interactions based on this authentication, including random power supply cutoffs and periodic interrogations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If secret authentication keys are stored in electronic circuits for product verification, then authentication capability is improved, but security against counterfeiting deteriorates because the keys can be compromised and pierced

Engineering Contradiction:

Improveauthentication capabilityVSAvoidcounterfeiting vulnerability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the authentication verification from static secret key comparison and relocates it to a dynamic physical process - the charge retention circuit's discharge behavior. The host device controls the initialization and measurement of the discharge time constant, removing the vulnerability of storing secret keys in the slave device while maintaining authentication capability through the unique discharge characteristics of the charge retention circuit.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The charge retention circuit serves as an intermediary element between the host device and slave device authentication process. Instead of directly comparing secret keys, the host device measures the discharge time constant of this intermediary circuit, which provides a physical layer of security that is difficult to replicate in counterfeit devices.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the power supply is switched off for authentication verification, then security verification is improved, but energy consumption increases and operation time is lost

Engineering Contradiction:

Improveauthentication verificationVSAvoidauthentication time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial action by switching off the power supply only for the minimal duration necessary to initialize the charge retention circuit and measure its discharge characteristics, rather than keeping the system fully powered or completely shut down. This reduces the time loss while maintaining authentication verification capability.

Inventive Principle:

Principle #16Partial or excessive action

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

Effectively verifies the authenticity of products by using the unique discharge characteristics of the charge retention circuit, preventing counterfeit products from being recognized as authentic, even if they possess the correct authentication key.

Implementation Method 1

initializing a charge retention circuit of a slave device... receiving an indication of a discharge time of the charge retention circuit

Methodology Applied

Scientific EffectCharge retention: Capacitance

Data Source

PatentUS10579832B2Detection of the authenticity of an electronic circuit or of a product containing such a circuit

Publication Date: 2020.03.03 STMICROELECTRONICS BELGIUM

AI summary

A method of authenticating a slave device. The method includes initializing, by a host device, a charge retention circuit of the slave device, and receiving, by the host device, an indication of a discharge time of the charge retention circuit. The host device authenticates the slave device based on the received indication of the discharge time of the charge retention device.