Hide Secret Messages In Facebook Photos Using This New Chrome Extension | Owen Campbell-Moore

Secretbook is a Chrome Extension I built as a research project in Oxford University (brief) which allows users to transmit completely secret messages on Facebook. These messages are hidden in photos so (without great effort) they cannot be detected by Facebook, Governments or prying friends.

Download the extension here and then hit ctrl+alt+a on Facebook to activate the secret new functionality. Any user with the correct password and extension installed can then decode the secret message by pressing ctrl+alt+a while looking at the photo in question.

200% zoom of before and after embedding a secret message. Changes are slight enough that without access to the original it would be impossible to visually detect the message.

The extension utilises a technique known as JPEG Steganography to hide secret messages in photos by making many visually imperceptible changes to encode the secret data. This technique has been demonstrated many times in the past although this is the first time software which allows the JPEGs to be recompressed (such as when uploaded to Facebook) without damaging the secret contents has been publicly available.

Steganography tools have traditionally been complicated (and often command line based) so a core goal to this project was to make Steganography easy and accessible so more people can take advantage of the privacy it provides.

Tools to detect steganography have existed for a long time and this extension is also susceptible - the advantage in this case is that 300+ million new photos are uploaded to Facebook every day so scanning them all (in addition to Facebook’s existing 250 billion photo database) would be highly computationally intensive. Governments also do not have access to privately shared Facebook albums so the risk of steganography being detected in a walled garden such as Facebook is much lower than for images shared on public websites such as eBay in the case of Al Qaeda in the past. In the past walled gardens have always recompressed JPEGs rendering previous steganography tools unusable – that is the true innovation this extension brings.

Full details of implementation are given in the following draft document.