Magnetic Card Reader Security via Equipotential Circuitry

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Magnetic card readers lack enhanced security measures to prevent illicit information retrieval through voltage tapping of electrical conductors, which is a significant concern in secure transactions.

Innovation Solution

A magnetic card reader design with a magnetic head in a non-secured region and signal paths extending to a secured region, where circuitry ensures a virtually zero voltage difference between conductors, using an operational amplifier and resistor configuration to prevent information retrieval, along with an impedance sensor and anti-tampering protection features like a doubled-over flat cable configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional magnetic card readers are used with electrical conductors extending from the magnetic head, then the device can read magnetic card information, but the electrical conductors are vulnerable to voltage tapping and illicit information retrieval

Engineering Contradiction:

ImprovesecurityVSAvoidcircuitry complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies equipotentiality by using an operational amplifier configured as a voltage follower to maintain equal voltage potentials between the first and second electrical conductors. The operational amplifier's high input impedance and low output impedance ensure that no voltage difference exists between the conductors, making voltage tapping ineffective for illicit information retrieval while preserving the normal signal transmission function.

Inventive Principle:

Principle #12Equipotentiality

2Ease of manufacture

If the magnetic head is placed in a non-secured region for ease of access, then the device structure is simpler, but the electrical conductors become accessible and vulnerable to tampering

Engineering Contradiction:

Improveassembly easeVSAvoidtampering risk

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary security enclosure that houses the operational amplifier circuitry and the vulnerable electrical conductors. This enclosure acts as a mediator between the non-secured region (where the magnetic head remains accessible) and the conductors, providing physical protection and security isolation without requiring the magnetic head itself to be enclosed, thus maintaining ease of manufacture while reducing tampering risk.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of information

If voltage difference is maintained between conductors for signal transmission, then information can be read from magnetic cards, but voltage tapping becomes possible and security is compromised

Engineering Contradiction:

Improveinformation retrievalVSAvoidvoltage tapping vulnerability

Core Design Contradiction:

Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of voltage tapping into a beneficial security feature by using the operational amplifier to actively maintain zero voltage difference between conductors. Any attempt to tap voltage between the conductors is automatically countered by the operational amplifier's feedback mechanism, which adjusts the voltage to maintain equipotential conditions, thus transforming the vulnerability into an active security protection mechanism.

Inventive Principle:

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

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 solution effectively prevents illicit information retrieval by maintaining a zero voltage difference and providing anti-tampering protection, reducing the risk of unauthorized access and data breaches in point-of-sale transactions.

Implementation Method 1

the circuitry located within the secured region including functionality ensuring that a voltage difference along the at least first and second electrical conductors is virtually zero

Methodology Applied

Scientific EffectOperational amplifier feedback control: Feedback

Implementation Method 2

a magnetic head having at least one signal output

Methodology Applied

Scientific EffectMagnetic signal detection: Electromagnetic Induction

Data Source

PatentUS7878397B2Enhanced security magnetic card reader especially useful in point of sale devices

Publication Date: 2011.02.01 VERIFONE INC

AI summary

A magnetic card reader including a magnetic head, located in a non-secured region, at least one signal path including at least first and second electrical conductors extending from the magnetic head in the non-secured region to a secured region, circuitry located within the secured region and receiving at least one signal output along at least one signal path, the circuitry located within the secured region including functionality ensuring that a voltage difference along the at least first and second electrical conductors is virtually zero, thereby obviating illicit information retrieval via tapping of the at least first and second conductors and analysis of voltage differences therebetween.