Physical shielding methods, such as wrapping cards in aluminum foil, create a Faraday cage effect that blocks the radio frequency signals used by scanners, effectively protecting credit cards from unauthorized RFID skimming.
The retrieved literature supports the efficacy of physical metallic shielding and Faraday-type enclosures in blocking radio frequency identification signals to prevent unauthorized scanning. Papers [7] and [8] specifically discuss how physical shielding successfully thwarts RFID attacks and reduces reading ranges.