Steganography is the art of concealing information. In computer science, it refers to hiding data within a message or file. It serves a similar purpose to cryptography, but instead of encrypting data, steganography simply hides it from the user.
Invisible ink is an example of steganography that is unrelated to computers. A person can write a message with clear or "invisible" ink that can only be seen when another ink or liquid is applied to the paper. Similarly, in digital steganography, the goal is to hide information from users except those who are meant to see or hear it.
Since steganography is more of an art than a science, there is no limit to the ways steganography can be used. Below are a few examples:
- Playing an audio track backwards to reveal a secret message
- Playing a video at a faster frame rate (FPS) to reveal a hidden image
- Embedding a message in the red, green, or blue channel of an RGB image
- Hiding information within a file header or metadata
- Embedding an image or message within a photo through the addition of digital noise
Steganography can also be as simple as embedding a secret message in plain text. Consider the following sentence:
"This example contains highly Technical expressions regarding modern simulations."
The first letter of each word produces the hidden phrase, "TechTerms."