Ethical Hacking (part 11.0/20): Introduction to steganography with examples and tools

How to hide secret messages inside digital objects

Note: by sharing knowledge of existing vulnerabilities, tools and countermeasures, we can prevent cyber criminals from taking inappropriate actions.

This article will cover:

1. Introduction to steganography
2. Step by step explanation of how it works
3. Steghide installation (available in Windows, Linux and Mac)
4. Hands on embedding a secret message into an image
5. Extras

Introduction to steganography

Steganography is a technique of hiding a secret message inside of a common object. It might be an image, a song, a pdf document or even an excel file.

For beginners, steganography may be confused with a cryptography. Generally, cryptography is based on techniques that mainly enables privacy. Steganography’s intention is to enable secrecy — and deceit.

Steganography has the advantage over cryptography in a sense that the secret message does not attract attention to itself as an object of scrutiny.

Nevertheless, the common practice is to combine cryptography and steganography together. Usually, firstly the secret message is being encrypted (cryptography) and then put secretly into some object (steganography).

Note: The word steganography comes from Greek steganographia, which combines the words steganós (στεγανός), meaning “covered or concealed”, and -graphia (γραφή) meaning “writing”.

Step by step explanation of how it works

Let’s see steps involved in steganography and see how the process looks like in very simple points:

1. First, we need to have an object where a secret message will be hidden. Let’s see an example of an image.

Note: we can use any digital object e.g. audio, pdfs or excel files because all of it is represented in bits.

This is our example image 10 x 10 pixels: