Exploring steganography: Seeing the unseen

TLDR

Steganography hides information so that its existence is concealed, employing techniques such as invisible inks, microdots, character arrangement, digital signatures, covert channels, and spread‑spectrum communications, and is distinct from cryptography, which merely scrambles content. The authors aim to examine how information can be hidden in image files and evaluate existing steganographic software. They analyze image‑based steganography by testing available software tools and provide a sidebar outlining the historical evolution of the technique. Their results show that steganography alone does not guarantee secrecy, nor does simple encryption, but combining the two yields stronger encryption.

Abstract

Steganography is the art of hiding information in ways that prevent the detection of hidden messages. It includes a vast array of secret communications methods that conceal the message's very existence. These methods include invisible inks, microdots, character arrangement, digital signatures, covert channels, and spread spectrum communications. Steganography and cryptography are cousins in the spycraft family: cryptography scrambles a message so it cannot be understood while steganography hides the message so it cannot be seen. In this article the authors discuss image files and how to hide information in them, and discuss results obtained from evaluating available steganographic software. They argue that steganography by itself does not ensure secrecy, but neither does simple encryption. If these methods are combined, however, stronger encryption methods result. If an encrypted message is intercepted, the interceptor knows the text is an encrypted message. But with steganography, the interceptor may not know that a hidden message even exists. For a brief look at how steganography evolved, there is included a sidebar titled "Steganography: Some History."