Monday, November 28, 2016

Steganography

Not actually Erin.
& is used with permission.
No, it's not a new dinosaur; steganography is the practice of hiding information (usually a message of some sort, often numeric) within a picture. While this was of limited utility in years past, the advent of personal computers and the Internet has made digital stegonography usable by all.

For example, let's say that you needed to give directions to a friend so that they could access your bug-out location, including such things as passwords, security codes, and the like, and you didn't want to transmit them in the clear (unless email is encrypted, it's "in the clear") but neither did you have time to deliver them written instructions.

The simple answer would be to send them an innocuous image (in my case, it would be a cute or funny My Little Pony picture as I have many of them on my computer, but in your case it might be a picture of your family, or a cute cat; just make sure that whatever you send is not "out of character" for you or for your recipient) with the relevant information encoded within it.
  1. Simply use an online stegonography service (like this one) to upload your image and compose your message. 
  2. Email the message to your friend, with a written clue (such as a specific phrase) that they should look for messages within the picture. 
  3. Your friend consults the same service, and using a predetermined password (do NOT include it in the message!) is able to read that message. 

There are of course a few drawbacks to this message:
  1. Your friend must remember both the clue phrase and the password.
  2. Your friend must realize that a message is being sent. 
  3. Your message isn't 100% private, as the online stegonography service knows the picture, the password, and the message. This is why an innocuous picture is important -- hide its importance by picking one that looks mundane!
As an example of how this works, a secret message has been hidden in a picture in this blog post. The password is the author's name.  Can you find it?

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