Back-Scattering Side Channels Flashcards
2 types of back-scatter
RF Tag - tag modules the signal to transmit its id
radar - use ‘reflection’ to guess what type of object
Bistatic
the transmit and receive antennas are at different locations
Monostatic
the transmit and receive antennas are the same antenna
Quasi-monostatic
the transmit and receive antennas are slightly separated, but appear to be in the same location from the POV of the target
Time delay ranging
measure the round-trip time of a signal to see how far away the target is
Radar Cross section
equation to determine what frequency we need to detect object correctly (size and pulse frequency)
Modulation Coefficient
proportional to the difference in reflection coefficient, determines how strongly modulated (aka readable) the signal will be
2 backscattering challenges
- Transmit signal will interfere with receive antenna
- Modulated signal is weak (further compounded by the fact that the Tx is really strong)
Impedance
measure of how an EM signal moves through a substance - When a EM wave in the air hits a substance, part of it is reflected back, and part is reflected through the substance. Impedance of a substance is proportional to impedance of air
backscattering sc differences from EM/Power Side Channel
- Not created by the current, we send a wave to the device and measure the impedance
- Impedance persists once we flip a NAND gate (instead of just a short burst)
- Modulate signal is square pulse
How effective was using back-scattering with EDDIE?
was weaker, but just as effective as EM/power
how can we effect power in backscatter SC?
can easily increase power by increasing carrier (unlike EM/power)
how can we effect frequency in backscatter SC?
We can choose carrier frequency to max SNR
How does distance affect backscatter SC?
Signal gets weaker for higher distance (worse than EM)
