A low and high side isolated current sensor with variable gain for side channel attacks

Isolated Balun-Based Variable Current Sensor

Sold by Stephan Electronics


No tax for United States [change]
a single 18650 cell holder to power the platform
Stock available: 96

Product Overview

This board has been designed with side channel attack measurements in mind.
It is meant to be inserted inline with supply rails, either on the high or low side.
A potentiometer allows you to vary the inline resistance, another one allows you to change the overall gain.

Frequency Response

The sensor frequency response for different shunt and gain potentiometers positions can be seen below.
From DC to 50MHz:

From DC to 1GHz:

As you can see, high frequencies get amplified the most, which will actually be beneficial in an attack measurement setup as wires will attenuate high frequencies.

Power Supply Setup

In side channel attacks, noise is your enemy.
In the center of the board you'll notice 0.1" header holes to solder a quiet 3.7V to 4.1V power supply source (pinout is shown at the back of the board). If you choose to solder a 18650 cell holder, rest assured the board contains a protection circuit against under/over voltage conditions.
Similarly, the power supply going to your attack target should also be very quiet.

Measurement Setup Advices

When performing side channel attacks the following rules should be followed:

  • eliminate any wires you may have, or keep them as short as possible
  • use clean power supplies (batteries, or lab PSU filtered by LDOs)
  • make sure your output isn't saturated (if so, add another resistance in //)
  • keep in mind that any connection may bring noise to your output
  • perform an FFT of your output with the platform off
  • make sure your trigger is repeatable

Required power supply

A clean power supply (between 3.6V and 4.2V) needs to be provided through the two holes in the top of the board. You may add a 18650 holder to your order in order to use a 18650 battery. Moreover, the board requires a CR1220 coin cell battery.

Links to code and documentation

Documentation (limpkin.fr)

Code (github.com)

Schematics (github.com)

Bom (github.com)

Shipping policy

All of our devices are shipped from Shenzhen, China. It takes between 2 to 3 weeks to receive your order.

The seller

Stephan Electronics

Lausanne, VD, Switzerland
46 orders since Apr 4, 2022
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