According to the article - as far as I remember - closed only means, that you need to closer to the passport.
> The official range of an e-passport’s RFID is supposed to be no more than ten centimetres (four inches). But with $100 worth of hobbyist gear, Israeli researchers managed to skim encrypted data off e-passports from several feet away. A student at Cambridge University in Britain went further, intercepting e-passport transmissions some 50 metres (160 feet) away.
> That was enough for State Department officials in Washington, DC, to insist that American e-passports be fitted with metal sleeves to shield them, when closed, from prying electronic eyes. The measures seem to be reasonably effective, though e-passports that get wedged open slightly by keys or loose change can still be read electronically from a distance.
> Slightly open passports could leave holders vulnerable to physical attack. Each country encrypts data in a characteristic way that terrorists could use to identify the nationality of the person carrying the chipped passport. To demonstrate the point, a firm called Flexilis used a partially opened American e-passport tucked in the pocket of a dummy to trigger an explosion as it passed a dustbin containing a small charge.
> The official range of an e-passport’s RFID is supposed to be no more than ten centimetres (four inches). But with $100 worth of hobbyist gear, Israeli researchers managed to skim encrypted data off e-passports from several feet away. A student at Cambridge University in Britain went further, intercepting e-passport transmissions some 50 metres (160 feet) away.
> That was enough for State Department officials in Washington, DC, to insist that American e-passports be fitted with metal sleeves to shield them, when closed, from prying electronic eyes. The measures seem to be reasonably effective, though e-passports that get wedged open slightly by keys or loose change can still be read electronically from a distance.
> Slightly open passports could leave holders vulnerable to physical attack. Each country encrypts data in a characteristic way that terrorists could use to identify the nationality of the person carrying the chipped passport. To demonstrate the point, a firm called Flexilis used a partially opened American e-passport tucked in the pocket of a dummy to trigger an explosion as it passed a dustbin containing a small charge.