The year is about to finish, and we all are ready for the final countdown to welcome to the New Year. It is time to review the famous cyber-attacks...

Have you ever done invisible ink when you were a kid? Apple juice, onion juice, potato juice and milk appear as invisible ink under the influence of heat. We had good fun writing invisible messages on papers to send our friends.

Steganography is just that, the art of hidden messages in front of everyone’s eyes. Not encrypted, just hidden. Cool, isn’t it?

It’s been used since ancient Greek times, when people used to hide messages within wax tablets that apparently contained innocent messages. The French Resistance also used it during World War II to write messages with invisible ink on the backs of couriers. And you can find many other examples of the usage of physical steganography that probes it not a child’s game.

Steganography is a very efficient way to deliver a secret message indeed. I am going to specifically talk about digital steganography, which is the modern version: Hiding digital content into another one.

There are several types of algorithms to make this possible. I am going to focus on a software called "Steghide" and will give you a small guide to use it. Steghide is available for Windows and Linux platforms and it’s free. Click here to download it!

Steghide is able to hide data in several types of image and audio files. It uses non relevant bytes in the carrier to embed the message to hide, and it uses Rijndael as the default encryption algorithm. You don’t really need to know how steganography is performed underneath, just know a few parameters to use along steghide command. So hands-on that it may prompt you to try and do on your own.

To embed a message into an image:
steghide embed –cf imageFile –ef messageTextFile
This will embed a message text on the "imagefile", that will be modified.

To set a specific output file when embedding:
steghide embed –cf imageFile –ef messageTextFile –sf outputImageFile
OutputImageFile will contained the embedded message.

To extract a message:
steghide extract –sf imageFile
And that will give you the message straight away.

You probably want to encrypt and hide your message at the same time, if this is your case use the parameter –p or –passphrase, like following:
steghide embed –cf imageFile –ef messageTextFile –p MYverystrongpassw0rd!
steghide extract –sf imageFile –p MYverystrongpassw0rd!

You have to know steganography makes files to increase their size, so if you hide 3,000 pages of your secret plans to rule the world in an innocent butterfly image, someone could find it suspicious as the final size of the file would be so big for such an innocent butterfly.

Steganography is so impressive, and the funny thing is the human eye cannot detect its hidden messages, Can you believe it? The thing that probes it is you’ve been looking at that "stegosaurus" image on this article all this time, and you haven´t noticed there is a hidden message on it!! Find the hidden surprise and tell us via "contact us" if you liked it!

Keep it secure!