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The Skim Reaper Is Coming to Protect You From Credit Card Theft

Security researchers will soon begin selling a tool that can tell when a thief is trying to steal your credit card information

2 min read
A newly designed Skim Reaper, which can be used to detect theft of credit card information at ATMs and other point-of-sale devices.
A newly designed Skim Reaper, which will go on sale in the coming weeks.
Photo: Nolen Scaife, Christian Peeters, Patrick Traynor

While consumers enjoy the ease at which a sale can be made with one swipe of a credit card, it also takes just one swipe for credit card theft to occur. Inside what looks like a regular point-of-sale device at the cashier’s counter or an ATM machine could be a skimmer, a gadget that records personal credit card information as you insert your card.

Hoping to put a fatal end to this type of credit card fraud, several years ago a group of researchers at the University of Florida created a device, aptly named the Skim Reaper, that detects skimmers. After some fine-tuning, sales of the Skim Reaper are poised to begin in the next few weeks.

The demand for such a tool has the potential to be very high, at a time when credit fraud is increasing at an alarming rate. A 2018 report found that 60 million U.S. payment cards were compromised over a 12-month period, 75 percent of which were compromised at a point-of-sale device.

The inventors of the Skim Reaper experienced this type of fraud first-hand, prompting them to develop the device. “Frankly, we were tired of getting ripped off,” says Nolen Scaife, a co-developer who is now an assistant professor at the University of Colorado Boulder. “So, we set out to make something that works.”

Credit cards store our personal information as variations in the magnetic properties of the dark strip across the top of the card. As you slide a card through a point-of-sale device, an interior component called a read head begins to register the magnetic information. When a skimmer is added to a point-of-sale device, it contains its own read head, which duplicates the information for fraudsters.

The Skim Reaper is a card-shaped tool that you can swipe through the point-of-sale device first, to register how many read heads it encounters. If it detects a second read head, this indicates that a skimmer is present.

An early prototype of the Skim Reaper, a device for detecting credit card theft at point-of-sales machines. An early prototype of the Skim Reaper, a device that can be used to detect credit card theft at point-of-sale machines.Photo: Nolen Scaife, Christian Peeters, Patrick Traynor

While the researchers first developed a prototype of a Skim Reaper several years ago, they’ve since been working to fine-tune it for commercialization.

“We’ve spent a lot of time working with our law enforcement and industry partners to better understand their needs and how the device performs in the field,” explains Scaife. “Since the initial prototypes, we have been working to place all of the equipment on a single card, which has fewer mechanical failure points and is more tailored to the use cases our partners need. We’re also eliminating the display on the prototypes and replacing them with LEDs to make it clear what the device is communicating.”

Details of the modified design were published in a study in IEEE Security & Privacy on 28 May. With sales poised to launch in the next few weeks, Scaife believes the initial customer pool will be made of businesses and law enforcement agencies. His team’s next goal is to create a new Skim Reaper design that allows the tool to be small enough to fit in a consumer’s pocket or wallet.

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The Inner Beauty of Basic Electronics

Open Circuits showcases the surprising complexity of passive components

5 min read
A photo of a high-stability film resistor with the letters "MIS" in yellow.
All photos by Eric Schlaepfer & Windell H. Oskay

Eric Schlaepfer was trying to fix a broken piece of test equipment when he came across the cause of the problem—a troubled tantalum capacitor. The component had somehow shorted out, and he wanted to know why. So he polished it down for a look inside. He never found the source of the short, but he and his collaborator, Windell H. Oskay, discovered something even better: a breathtaking hidden world inside electronics. What followed were hours and hours of polishing, cleaning, and photography that resulted in Open Circuits: The Inner Beauty of Electronic Components (No Starch Press, 2022), an excerpt of which follows. As the authors write, everything about these components is deliberately designed to meet specific technical needs, but that design leads to “accidental beauty: the emergent aesthetics of things you were never expected to see.”

From a book that spans the wide world of electronics, what we at IEEE Spectrum found surprisingly compelling were the insides of things we don’t spend much time thinking about, passive components. Transistors, LEDs, and other semiconductors may be where the action is, but the simple physics of resistors, capacitors, and inductors have their own sort of splendor.

High-Stability Film Resistor

A photo of a high-stability film resistor with the letters "MIS" in yellow.

All photos by Eric Schlaepfer & Windell H. Oskay

This high-stability film resistor, about 4 millimeters in diameter, is made in much the same way as its inexpensive carbon-film cousin, but with exacting precision. A ceramic rod is coated with a fine layer of resistive film (thin metal, metal oxide, or carbon) and then a perfectly uniform helical groove is machined into the film.

Instead of coating the resistor with an epoxy, it’s hermetically sealed in a lustrous little glass envelope. This makes the resistor more robust, ideal for specialized cases such as precision reference instrumentation, where long-term stability of the resistor is critical. The glass envelope provides better isolation against moisture and other environmental changes than standard coatings like epoxy.

15-Turn Trimmer Potentiometer

A photo of a blue chip
A photo of a blue chip on a circuit board.

It takes 15 rotations of an adjustment screw to move a 15-turn trimmer potentiometer from one end of its resistive range to the other. Circuits that need to be adjusted with fine resolution control use this type of trimmer pot instead of the single-turn variety.

The resistive element in this trimmer is a strip of cermet—a composite of ceramic and metal—silk-screened on a white ceramic substrate. Screen-printed metal links each end of the strip to the connecting wires. It’s a flattened, linear version of the horseshoe-shaped resistive element in single-turn trimmers.

Turning the adjustment screw moves a plastic slider along a track. The wiper is a spring finger, a spring-loaded metal contact, attached to the slider. It makes contact between a metal strip and the selected point on the strip of resistive film.

Ceramic Disc Capacitor

A cutaway of a Ceramic Disc Capacitor
A photo of a Ceramic Disc Capacitor

Capacitors are fundamental electronic components that store energy in the form of static electricity. They’re used in countless ways, including for bulk energy storage, to smooth out electronic signals, and as computer memory cells. The simplest capacitor consists of two parallel metal plates with a gap between them, but capacitors can take many forms so long as there are two conductive surfaces, called electrodes, separated by an insulator.

A ceramic disc capacitor is a low-cost capacitor that is frequently found in appliances and toys. Its insulator is a ceramic disc, and its two parallel plates are extremely thin metal coatings that are evaporated or sputtered onto the disc’s outer surfaces. Connecting wires are attached using solder, and the whole assembly is dipped into a porous coating material that dries hard and protects the capacitor from damage.

Film Capacitor

An image of a cut away of a capacitor
A photo of a green capacitor.

Film capacitors are frequently found in high-quality audio equipment, such as headphone amplifiers, record players, graphic equalizers, and radio tuners. Their key feature is that the dielectric material is a plastic film, such as polyester or polypropylene.

The metal electrodes of this film capacitor are vacuum-deposited on the surfaces of long strips of plastic film. After the leads are attached, the films are rolled up and dipped into an epoxy that binds the assembly together. Then the completed assembly is dipped in a tough outer coating and marked with its value.

Other types of film capacitors are made by stacking flat layers of metallized plastic film, rather than rolling up layers of film.

Dipped Tantalum Capacitor

A photo of a cutaway of a Dipped Tantalum Capacitor

At the core of this capacitor is a porous pellet of tantalum metal. The pellet is made from tantalum powder and sintered, or compressed at a high temperature, into a dense, spongelike solid.

Just like a kitchen sponge, the resulting pellet has a high surface area per unit volume. The pellet is then anodized, creating an insulating oxide layer with an equally high surface area. This process packs a lot of capacitance into a compact device, using spongelike geometry rather than the stacked or rolled layers that most other capacitors use.

The device’s positive terminal, or anode, is connected directly to the tantalum metal. The negative terminal, or cathode, is formed by a thin layer of conductive manganese dioxide coating the pellet.

Axial Inductor

An image of a cutaway of a Axial Inductor
A photo of a collection of cut wires

Inductors are fundamental electronic components that store energy in the form of a magnetic field. They’re used, for example, in some types of power supplies to convert between voltages by alternately storing and releasing energy. This energy-efficient design helps maximize the battery life of cellphones and other portable electronics.

Inductors typically consist of a coil of insulated wire wrapped around a core of magnetic material like iron or ferrite, a ceramic filled with iron oxide. Current flowing around the core produces a magnetic field that acts as a sort of flywheel for current, smoothing out changes in the current as it flows through the inductor.

This axial inductor has a number of turns of varnished copper wire wrapped around a ferrite form and soldered to copper leads on its two ends. It has several layers of protection: a clear varnish over the windings, a light-green coating around the solder joints, and a striking green outer coating to protect the whole component and provide a surface for the colorful stripes that indicate its inductance value.

Power Supply Transformer

A photo of a collection of cut wires
A photo of a yellow element on a circuit board.

This transformer has multiple sets of windings and is used in a power supply to create multiple output AC voltages from a single AC input such as a wall outlet.

The small wires nearer the center are “high impedance” turns of magnet wire. These windings carry a higher voltage but a lower current. They’re protected by several layers of tape, a copper-foil electrostatic shield, and more tape.

The outer “low impedance” windings are made with thicker insulated wire and fewer turns. They handle a lower voltage but a higher current.

All of the windings are wrapped around a black plastic bobbin. Two pieces of ferrite ceramic are bonded together to form the magnetic core at the heart of the transformer.

This article appears in the February 2023 print issue.