An Overview of Steganography for the Computer Forensics Examiner

author:Gary C. Kessler
Associate Professor
Computer and Digital Forensics Program
Champlain College
Burlington, Vermont

Abstract

Steganography is the art of covered or hidden writing. The purpose of steganography is covert communication—to hide the existence of a message from a third party. This paper is intended as a high-level technical introduction to steganography for those unfamiliar with the field. It is directed at forensic computer examiners who need a practical understanding of steganography without delving into the mathematics, although references are provided to some of the ongoing research for the person who needs or wants additional detail. Although this paper provides a historical context for steganography, the emphasis is on digital applications, focusing on hiding information in online image or audio files. Examples of software tools that employ steganography to hide data inside of other files as well as software to detect such hidden files will also be presented.