• electromagnetism
• filter
• frequency-selective surface
• information leakage
• metamaterial
• physical layer
• physical layer security
• shielding
• shielding effectiveness
• side-channel attack
• unwanted emission

Traditionally, when thinking about cybersecurity and the ways to defend valuable assets the common thought is directed towards software tools. However, considering that attackers' skills are improving at a very fast pace it is essential to broaden the defender's mindset by paying attention also to those cyber threats originating from the lowest layer of the protocol stack: the physical layer. This work focuses on side-channel attacks exploiting electromagnetic waves and proposes a methodology to address these threats based on the theoretical concept of shielding. It discusses a step-by-step process to design, build and experimentally validate the prototype of a frequency-selective surface capable of shielding against electromagnetic waves at specific frequencies. Furthermore, it is taken even a step forward by developing a reconfigurable version of the metamaterial, whose operational state can be modified according to the user's needs.