If you own a wireless keyboard, you'll want to ensure the connection is encrypted, lest the bad guys spy on every letter you type. In a study that just came out, as reported in The Atlantic, hackers can sit hundreds of feet away and steal every keystroke typed by an unsuspecting user.
Researches test eight wireless keyboards produced by major manufacturers and discovered that data was being transmitted in plain text which could easily be stolen. Using equipment bought on Amazon.com for less than $100, they were able to eavesdrop on a victim without them even realizing it.
The list of vulnerable devices can be found here.
Keyboards that connect via Bluetooth are safe and couldn't be hacked using this method, because Bluetooth encrypts the data transmission.
The experts say that if one owns one of these wireless keyboards, there's no way to encrypt the data, so it's best to just throw it out and buy a secure one.