IDA Computer Science Steganography and Its Implications for Security Report

Refer to “Steganography and Its Implications for Security”

What Is Steganography?
The art of steganography is an old practice but the science of it comes to fruition in the computer age. For
centuries people have concealed information from view using various methods, and computers make the
concealment methods more sophisticated.
Basic elements of system steganography include:
▪ Secret message (information to conceal)
▪ Embedding algorithm (method for concealing the information)
▪ Carrier medium (unsuspecting document, image, audio, or video file)

The intent is to store and/or transmit secret messages hidden in an innocuous carrier medium. Good
steganography is imperceptible: it doesn’t significantly distort or degrade the quality of the carrier
medium. For example, it’s possible to disguise a secret message entirely within spam email such that it
reads like any other bogus email without revealing any secrets.

The capacity for concealed data is confined to the type of message and the carrier medium. Given a large
enough audio or video file any amount of secret data can be stashed away. Robustness, the ability to
survive manipulation of the medium to modify embedded data, depends on the method and algorithm.

Steganography is used in conjunction with cryptography for dual–layer protection. For a third layer, a
technique called chaffing and winnowing is used, which is a method of interleaving bogus data between
slices of real data to avoid reassembly by undesired parties. Steganography, cryptography, and chaffing
and winnowing are combined to construct messages such that no third–party can identify the original
message. Imagine the following implications:
▪ Data concealment by encrypted or randomized data
▪ Concealment in tampered executable files
▪ Covert channels in system processes and network protocols
▪ Plaintext messages hidden in other plaintext messages

Detection requires careful inspection and thorough examination called steganalysis, the detection of
stenographical encoded messages. Sometimes messages can be revealed by comparing original and
modified forms (text files, executables) where possible. Otherwise, embedding data leaves statistical
anomalies or artifacts that are detectable by “binary similarity measures”.

Please write a summary report on the significance of steganography and how it affects security and forensic investigations.