Unseen An Overview of Steganography and Presentation of Associated Java Application C Hide Unseen An Overview of Steganography and Presentation of Associated Java Application C Hide Jessica Codr jmc5 cec wustl edu A project report written under the guidance of Prof Raj Jain Download ABSTRACT People have desired to keep certain sensitive communications secret for thousands of years In our new age of digital media and internet communications this need often seems even more pressing This paper presents general information about steganography the art of data hiding The paper provides an overview of steganography general forms of steganography specific steganographic methods and recent developments in the field The information presented in this paper is also applied to a program developed by the author and some sample runs of the program are presented KEYWORDS steganography steganalysis data hiding data security data embedding stego objects watermarking secret communications secret messages hidden messages hidden channel covert channel LSB alterations TABLE OF CONTENTS 1 Introduction and Overview 1 Steganography Versus Cryptology 2 Characteristics of Strong Steganography 3 Origins of Steganography 2 Cover Media and General Steganography Techniques 1 Digital Media 2 Text 3 Network Communications 3 Specific Steganographic Tactics 1 Least Significant Bit Alterations 2 Transform Domain Techniques 3 Data Dispersal and Feature Modification Techniques 4 Non Image Techniques 4 Cutting Edge Developments 1 Novel View of Steganography 2 Advances with JPEGs 3 Advances with Networks 4 Steganalysis and Artificial Intelligence 5 Other Recent Developments http www cse wustl edu jain cse571 09 ftp stegano index html 1 of 21 Unseen An Overview of Steganography and Presentation of Associated Java Application C Hide 5 Author s Application and Conclusions 1 My Application Description 2 My Application Results and Evaluation 3 Final Conclusions References Acronyms Appendix A Additional Terms Appendix B Puzzle Solutions Appendix C Java Application Design Choices 1 Introduction and Overview Have you ever set up code words for talking with your friends so that you could convey something to them without those nearby knowing you were doing so Perhaps you established a code word or signal to be used at a party to indicate you were bored and ready to go home or if you are more devious established a system to cheat at a card game If you have done anything like this you have used steganography Steganography is the art of hiding a message so that only the intended recipient knows it is there In the most widely cited description of steganography two prisoners Alice and Bob are trying to plan a jail escape while under the watchful eye of Warden Wendy Wendy will not tolerate suspicious behavior such as passing notes that are clearly encrypted So Alice and Bob communicate such that it seems they are talking about something harmless such as the weather or their families when they are actually planning an escape cited in Bergmair06 from Simmons84 From this simple theoretical example many steganographic techniques and practices have spawned and have helped improve data security in the real world 1 1 Steganography Versus Cryptology In the real world steganography like cryptology is intended to add a layer of security to communications so that pesky eavesdroppers don t know what Alice is saying to Bob However unlike cryptology steganography is not meant to obscure the message but to obscure the fact that there is a message at all Attacks against cryptography take what is known to be an encrypted message and attempt to decrypt the message Attacks against steganography take what seems to be an ordinary image text multimedia file or other document and determine whether or not there is another message hidden within Steganography and cryptography are strongest when combined A message sent in secret steganography in an encrypted form cryptography is much more secure than a plain text message sent by secret means or a clearly sent encrypted message There are some cases in which steganography can take the place of cryptography for instance German bans on encrypting radio communications were recently countered by applying steganography to radio communications Westfeld06 Generally however steganography is not intended to replace cryptography but supplement it Johnson95 Steganography like cryptography also has its own set of terminology In steganography cover refers to the media in which a message is hidden Covertexts and coverimages are texts and images used as covers respectively A stego object is the cover with the secret message embedded in it Steganography also has an additional branch known as watermarking which is a means of hiding data within a cover in order to mark that cover and prevent duplication or unauthorized use Whereas pure steganography hides data completely watermarking is meant to be detectable but unalterable Watermarks can be applied to text documents containing intellectual property art work music files movies or anything that an author or owner does not want others to use or copy without proper authorization The watermark verifies a media file http www cse wustl edu jain cse571 09 ftp stegano index html 2 of 21 Unseen An Overview of Steganography and Presentation of Associated Java Application C Hide owner s right to use it If the watermark can be removed systems that check watermarks to see if the user is authorized to have the media just see an ordinary file with no protection and allow the owner to use it Thus watermarks must be hidden so as not to damage the media and must be detectable by an outside system but not removable Lu05 Katzenbeisser00 This discussion of the purpose of watermarking leads into a more general discussion of the goals of strong steganography presented in the next subsection 1 2 Characteristics of Strong Steganography Though steganography s most obvious goal is to hide data there are several other related goals used to judge a method s steganographic strength These include capacity how much data can be hidden invisibility inability for humans to detect a distortion in the stego object undetectability inability for a computer to use statistics or other computational methods to differentiate between covers and stego objects robustness message s ability to persist despite compression or other common modifications tamper resistance message s ability to persist despite active measures to