Radio frequency identification isn't new. The basic concepts have been around since the 1940s, but thanks to economies of scale, better manufacturing processes and more capable back-end data management, the technology is coming of age. We're seeing the tags in everything from poker chips to passports, and it has created significant concerns in some security circles. One expert worried about RFID is Adam Laurie, who has accumulated considerable practical knowledge of short-range radio technologies. Laurie, who recently mounted an attack on the UK Government's RFID-enabled passport for the Times newspaper, explains the underlying mechanics of the technology - and its weaknesses. Many people will be familiar with RFID technology without being aware of what it is, to what degree it is being deployed in the modern world, or even that it exists at all. Most of us will have come into contact with it either through an access control system such as a 'Prox' card or keyfob, used to gain access to our buildings. In the UK, the Transport for London 'Oyster' card carries an RFID chip^1. In the near future, all European citizens will carry one when they travel abroad, in the form of an 'ePassport', and possibly even when walking the streets in the UK, with the proposed national ID card^2. But how secure is this technology, and can we really trust it with our most precious data or the security of our cars, alarm systems, and buildings?