A British student has released a Google Chrome extension that enables you to hide secret messages in your Facebook pictures.  Owen Campbell-Moore, studying computer science at Oxford University, used a technique called JPEG Steganography to make tiny changes in photos that form a secret code. Called 'Secretbook', you can now download it and communicate with your friends without anybody else knowing you are doing it.

The extension can only be used with Google Chrome and messages can only be 140 characters.  Usually when such altered photographs are recompressed, any message is garbled -- but Campbell-Moore found a way around this by having the extension automatically compress the message before it is uploaded to Facebook.

Campbell-Moore said the goal of this research was to demonstrate that JPEG steganography can be performed on social media where it had previously been impossible.

Nobody can read these messages unless they have the password created by the user, including Facebook itself. Tools do exist to detect steganography in pictures, but because hundreds of millions of pictures are uploaded to Facebook each day, it is far more difficult for them to detect this extension. The privacy settings on photo albums also prevent any possibility of government access.

As well as providing an easy way to enhance your privacy, this does create the possibility that extremists may use the extension for their own purposes; but as it is not completely flawless, Campbell-Moore believes they will avoid it.

You can download the extension from the Chrome Web Store here.