What you type on an ordinary keyboard can no longer be considered secure, as scientists have discovered a way to analyse the electromagnetic signals produced by every key press - even at a distance of 20 metres.

Studying the signals made by keystrokes Swiss researchers from the Security and Cryptography Laboratory at the Swiss Ecole Polytechnique Federale de Lausanne have been able to reproduce what the subject typed.

The researchers used a radio antenna to "fully or partially recover keystrokes" and managed to develop four different "attacks" that work on a variety of computer keyboards.

Keyboards that connect via USB or a PS/2 socket were vulnerable as were keyboards embedded in laptops. The researchers state that keyboards are "not safe to transmit sensitive information".