Page 34 - EngineerIT July 2022

TECHNOLOGY

Technology reacts to the slightest
changes
Tiny changes to the system are enough
to have a noticeable effect on the
fingerprint, as a demonstration by
the two researchers shows: they have
built their radio technology into an old
computer housing. The measured radio
signal is rendered visible on a laptop as
a curve that shows the strength of the
signal at different frequencies in real
time. Then, Staat and Tobisch unscrew
one of the screws on the outside of the
housing a little. The frequency curve
reacts with a noticeable deflection that
wasn’t there before.
A high-precision robot inserts the needle into the computer through holes in the housing. For this
to work, the researchers first had to teach the robot where the holes were located – and some of
Measurements while the the needles broke in the first attempts © Michael Schwettmann
computer’s running
“A unique aspect of our approach is remains stable over a prolonged period. Later, they even extended the measurement
that we are carrying out the experiment period to a whole month. In addition to expensive high-precision measuring technology for
while the computer is running,” points recording the fingerprint, they also compared the radio signal with simple technology that
out Tobisch. This causes all kinds of sells for a handful of euros. They found that this technology did the job, too, albeit with a
interference. “The fans are like little slightly lower hit rate. “It’s always a compromise between cost and accuracy,” says Staat.
hoovers and the processor is like Depending on the intended use, the impact of ambient conditions would also have
a heater,” illustrates Staat. These to be taken into account. After all, if the temperature or humidity in the room changes,
fluctuations in the ambient conditions these changes can also affect the radio fingerprint. “We hope to tackle such problems
affect the radio signal. The researchers in the future with the help of machine learning,” anticipates Tobisch. The idea is that
have to measure such disturbances and artificial intelligence could autonomously learn which changes in the radio signal are due
factor them out in order to determine to non-critical changes in the surroundings and which are due to manipulation.
whether fluctuations in the signal are
legitimate or the result of manipulation. Broad application possible
The IT experts from Bochum can “Fundamentally, there’s nothing standing in the way of a broad application of this
reliably detect the penetration of a technology. It is suitable for both high-security applications and everyday problems,”
needle 0.3 millimetres thick with their stresses Christian Zenger, founder and CEO of PHYSEC. The IT company already uses the
system from a penetration depth of one technology to prevent unauthorised manipulation of critical infrastructure components.
centimetre. The system still detects a “There are plenty of other technical systems that need to be protected, not only from
needle that is only 0.1 millimetres thick remote cyberattacks but also from hardware manipulation,” he adds. “Examples include
– about as thick as a hair – but not in control units in cars, electricity meters, medical devices, satellites and service robots.” n
all positions. “The closer the needle is
to the receiving antenna, the easier it is
to detect,” explains Staat. The thinner
and further away the needle, the more
likely it is to go undetected. The same
applies to the penetration depth: the
deeper the needle is in the system,
the easier it is to detect. “Therefore, in
practical applications, it makes sense to
think carefully about where you place
the antennas,” as Tobisch sums up the
findings. “They should be as close as
possible to the components that require
special protection.”
Tobisch and Staat allowed their
experiment to run for ten days, thus Detecting hardware manipulations - Bochum researchers Paul Staat and Johannes Tobisch are
showing that the measuring system developing a technique that uses radio waves to detect tampering with hardware.

EngineerIT | July 2022 | 32