Wednesday, November 07, 2018

I see what you're doing there

Researchers have found a way to see through walls using ambient Wi-Fi signals and an ordinary smartphone.
They say the new technique allows an unprecedented invasion of privacy. “Bad actors using smartphones can localize and track individuals in their home or office from outside walls, by leveraging reflections of ambient Wi-Fi transmissions.”
Humans reflect and distort a Wi-Fi signal. The distortion, and the way it moves, would be clearly visible through Wi-Fi eyes, even though the other details would be smeared. This crazy Wi-Fi vision would clearly reveal whether anybody was behind a wall and, if so, whether the person was moving.
First they locate the transmitter.
It is even possible to work out exactly where the transmitter sits inside a house, because floor plans of most homes and offices in the US are downloadable from places such as real estate websites. 
The researchers say that by walking back and forth a few times outside a room or building, they can reliably locate the transmitter. “We found that consistency check across 4 rounds of measurements is sufficient to achieve room level localization of 92.6% accuracy on average,” they say.
Various movements change the signal in different ways. For example, opening a door changes the field in two adjacent rooms and thus is straightforward to spot. Walking around creates large distortions, and even an action like typing creates small changes that a smartphone Wi-Fi receiver can pick up.
What if your wife gets one of these? Yikes.

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