It's curtains for data security

The data on any monitor can be read remotely via reflections in teapots, teaspoons, coffee cups or spectacle lenses – or even the eyes of a PC user. This was discovered during research by computer scientists at Saarland University. Using a special telescope setup, they were able to reconstruct the information shown on a screen from a distance of up to ten metres, from its reflection in various objects. The necessary equipment is said to have cost only €1000.

The research team concludes that with more professional equipment, secret data could easily be read off in this way from a greater distance, possibly from the windows of a neighbouring building. Criminals could use this technique, they warn, for industrial espionage, to snoop on bank data or to shadow politicians and prominent figures. The research results are to be presented at CeBIT 2008 from 4 to 9 March on the Saarland research stand (Hall 9, Stand B 35).

The content shown on the monitor is easier to recognise the less the eye moves and the closer the user is to it.

Reflections in the spectacle lenses of PC users are said to be particularly suitable for spying on information. The team reports that text in a 12-point typeface can be deciphered easily from a distance of ten metres. Even the human eye can act as a mirror within certain limits. Test images were admittedly blurred, but it was possible nevertheless to recognize headings, as well as displayed web sites and diagrams. Exposure times of one second were sufficient for photographing individual web sites through a telescope. Rapid motions of the eye caused problems with recognition. But, say the scientists, better equipment and improved algorithms could soon compensate for this.

The scientists achieved their best results with stationary objects, such as reflective teapots. Using image-processing software, they easily corrected images that had been distorted by curved surfaces.

They say that at present, people aware of the dangers described can only protect themselves by closing blinds or curtains when handling confidential data, and by watching out for concealed telescopes. The research team intends to present its results at the international "IEEE Symposium on Security and Privacy" in the US in May 2008.

See also:

• Compromising Reflections: How to read Computer Monitors around a Corner, study by Michael Backes, Markus Dürmuth and Dominique Unruh

(mba)