After watching Surveilled on HBO last night (which was an expectedly overly sensationalist documentary with Ronan Farrow as the self centered host), they showed

After watching Surveilled on HBO last night (which was an expectedly overly sensationalist documentary with Ronan Farrow as the self centered host), they showed a security researcher wrapping a laptop with aluminum foil to stop signal from reaching it. Asking google about it was not helpful.