The art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient could understand or view is called Steganography.
According to the Wikipedia, The word steganography is of Greek origin and means “concealed writing” from the Greek words steganos (στεγανός) meaning “covered or protected”, and graphei (γραφή) meaning “writing”.
In this post I’m going to show how to create such covered or protected message. In this we are going to hide a text file inside a Image (.jpg) file.
This is what you need before starting the procedure :
1. A computer with setghide application installed on it.
( Steghide is a free steganography program that is able to hide data in various kinds of image- and audio-files. http://steghide.sourceforge.net/ )
2. A .jpg image and a .txt file to hide.
This is how to do it :
1. First install steghide in your computer. In Ubuntu you can just type this in terminal to install it right away.
1 sudo apt-get install steghide
2. Now it’s time to hide the text file inside the Image file. (I’ll take Text.txt is my text file and Image.jpg is my image file). Now simply type this in your terminal
1 steghide embed -ef Text.txt -cf Image.jpg
3. Once you execute that line the terminal will prompt you for a Pass phrase. type any pass phrase of your own for this. but that pass phrase will be needed when you needed to extract the text from the Image file. Then the process is complete.
4. Now we have Image.jpg which has Text.txt embedded on it. To extract it you just have to simply type this in your terminal
1 steghide extract -sf Image.jpg
5. Then it will prompt for that Pass phrase you gave it while you were embedding that Text.txt to the Image.jpg. Once you entered your pass phrase it will extract the content which is hidden inside that .jpg file.