The financial world is forever struggling to implement effective security against fraud. The newest schemes rely on the much-improved ability of computers to match patterns. These examine some pattern linked to the user and check that it matches that stored in its records, in a technique called biometrics. Among the suggested patterns are hand shape, the timbre of the voice, and even body odour. Fingerprints are another, known to be unique to each individual, but criminals may be able to fake these with special slip-over plastic gloves, and the patterns are difficult to digitise with confidence. As a result, attention has turned to the eye, whose iris pattern is also known to be uniquely linked to the individual. The computer scans the customer’s eye, identifies the iris pattern, and converts it to a short digital code, the iris code, which is then checked against the one stored. It is claimed that a new system using this idea, called iris scanning, can examine eyes from three feet away even if the person is wearing contact lenses or spectacles, even in the dark. It may be implemented as a secure identification scheme for hole-in-the-wall bank teller machines.