Digital Rights Lounge
Hidden Text in Images - Steganography Demo and CTF

Short thesis

Hands-on with Image Steganography. Showing how it's done, detected followed by a Capture The Flag (CTF) challenge.


Steganography is the area that deals with the study and application of techniques that hide messages or objects within other messages or objects (called carriers) so that they are not detected. The very concept of steganography comes from the Greek word steganos, which means covered or hidden, and graphos, which means writing. An example of this type of technique (and perhaps of the best-known type of steganography) is to hide a message among the bits of an image in such a way that in the event that the image were to be intercepted by a third party, they would only see the image, not the message hidden in it. 

In this workshop we will be using common techniques to hide messages in images and we will be performing a steganalysis to detect hidden messages. This will be followed by a small CTF challenge session for the participants.

Capture the Flag (CTF), a type of cryptosport, is a computer security competition. CTF contests are usually designed to serve as an educational exercise to give participants experience in securing a machine, as well as conducting and reacting to the sort of attacks found in the real world. In this CTFs participants can work in teams or as individuals to solve the challenges. Answers and how-tos will be revealed at the end. 

Participants are expected to bring their own laptops to take part in the CTF.

The video that was covered during the session:

The example and tool: