Wireless keyboards are a great convenience. However, they are also insecure. Most Bluetooth keyboards radiate signals in all directions for a MINIMUM of 30 feet and some of them can send as far as 100 meters or 328 feet. A few may transmit even further.
NOTE: Class 1 Bluetooth devices transmit at 100 milliwatts (on-tenth of a watt) which results in a standard range of approximately 100 meters or 328 feet, range is comparable to that of an 802.11b WLAN device. Class 1 devices are most commonly implemented in devices where power is plentiful, such as laptop and desktop systems. However, most Bluetooth keyboards transmit with less than 100 milliwatts.
A hacking tool called Keysniffer allows any hacker with a $12 radio device to intercept the connection between any of eight wireless keyboards and a computer from 250 feet away. What’s more, it gives the hacker the ability to both type keystrokes on the victim machine to and silently record the target’s typing. All this works by intercepting keyboard keystrokes. Use of a VPN (virtual private network) or other security software is ineffective against Keysniffer.