Stuck on the tarmac, flipping through a travel magazine, you’re struck by the blurb for metal-lined wallets. Purpose: to prevent digital pickpocketing by blocking radio frequencies.

Your reaction: Wow! Luxury accessories for paranoids!

But you would be wrong. Maybe.

Because, says electronic security expert Bruce Schneier, crystallizing the view of many: “As weird as it sounds, wrapping your passport in tinfoil helps. The tinfoil people, in this case, happen to be correct.”

The issue is bigger than just the new style of passports, which contain chips that emit information that can be read by a scanner. New credit cards, such as MasterCard’s PayPass, don’t have to be swiped through a machine, either. Conceivably, a pickpocket with a laptop and an antenna could lift the digital contents of your wallet.

The scenario has been reenacted by hackers under simulated conditions, though the makers and issuers of these cards insist your data is encrypted and safe. And a spokesmen for the State Department and the Department of Homeland Security says that even when passport books are open, the digital information can be read by a scanner no more than a few inches away.

But if the specter of unauthorized leaks from your hip pocket keeps you awake at night, Geb Masterson, president of Kena Kai in Anaheim Hills, Calif., will sell you one of his DataSafe models. The shielding material is a thin “metalized nylon,” finished for the style-conscious with fine Italian leather. The result is no heavier than a standard leather wallet, says Masterson, who adds that he has sold more than 50,000 in less than two years. Prices start at $79.99.

Even more affordable: tinfoil.