‘Secretbook’ Lets You Encode Hidden Messages in Your Facebook Pics

[Owen Blacker]

http://www.wired.com/dangerroom/2013/04/secretbook/

Facebook is a place where you can share pictures of cute animals and fun
activities. Now there’s a browser extension that lets you encode those
images with secret, hard-to-detect messages.

That’s the idea behind
Secretbook<https://chrome.google.com/webstore/detail/secretbook/plglafijddgpenmohgiemalpcfgjjbph>,
a browser extension released this week by 21-year-old Oxford University
computer science student and former Google intern Owen-Campbell Moore. With
the extension, anyone — you, your sister, a terrorist — could share
messages hidden in JPEG images uploaded to
Facebook<http://www.wired.com/magazine/2013/04/facebookqa/> without
the prying eyes of the company, the government or anyone else noticing or
figuring out what the messages say. The only way to unlock them is through
a password you create.

“The goal of this research was to demonstrate that JPEG steganography can
be performed on social media where it has previously been impossible,”
Campbell-Moore tells Danger Room. He says he spent about two months spread
out over the last year working on the extension as a research project for
the university.

[…]

It wasn’t easy developing the extension. “Many tools for steganography in
JPEGs have existed in the past although they have always required that the
images are transmitted exactly as they are,” Campbell-Moore says.

This could be a single pixel changed to a different color, and then
repeated over several images, spelling out a message — which you can’t see,
unless you have the translation key, and know which pixel to look for. But
when you upload an image to Facebook, the image is automatically
recompressed, which can lower the image quality. If you’ve encoded a secret
message in the image, Facebook will garble
it<http://www.owencampbellmoore.com/blog/2013/04/hide-secret-messages-in-facebook-photos-using-this-new-chrome-extension/>.
Facebook competitor Google+ doesn’t do this, so you can share encoded
messages <http://www.greatplay.net/essays/steganography-in-social-media> there
without needing an app for it.


[continues…]
-- 
Owen Blacker, London GB
@owenblacker <http://twitter.com/owenblacker>
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