Japanese researches claim to have developed a special paint that can improve wireless network security by blocking out signals.
The paint contains aluminium-iron oxide that can absorb and block wireless network signals.
Businesses could coat offices with the paint to ensure wireless signals cannot be monitored from outside, the researchers have told the BBC.
The University of Tokyo researchers said the paint is a quick and cheap way of preventing access to sensitive data from unauthorised users.
But security experts have said the of electromagnetic shielding techniques is nothing new and not a complete solution as it blocks only eavesdroppers and fails to stop hackers and other intruders.