Steganography

The ldquoKeysrdquo to the Kingdom

Presented By Mustahid ali

ContentsCommunication

What is cryptography

What is steganography

Steganography in digital images

Communication has always been the need for the social system we live in the primitive man use designs sounds and later on developed the art of speaking and writing languages with the purpose of communicating efficiently And today we find ourselves surrounded by the jargon of internet which is one of the most efficient and fastest means of communication throughout the globeWhenever there is a communication link there has always been a ldquoRecipientrdquo for whom the message is meant and a ldquoSenderrdquo who is sending the message But as is always the case there is a third person called ldquoThe Miscreantrdquo or the ldquoIntruderrdquo trying to intercept the message or block it before it reaches destination Ancient Greeks and other civilizations used many forms of simple techniques to evade the detection of message by hiding it or making it unreadable

Examples are

Tatoos on scalp Dots on top of lsquoirsquo and lsquojrsquo Deliberate misspellings or Error Writing with invisible ink

Introduction

Cryptography

It is the process of converting the message into an unreadable format A simple method is to convert the text into binary (based on ASCII value) Now using a key known only to the sender and recipient we can XOR the data This is known as a XOR cipher

Ciphertext = Plaintext (XOR) Key

Plaintext = Ciphertext (XOR) Key

The output would have an unreadable format like the one below

LDPKD YLQJD JUHDW WLPHK HUHLQ

To an intruder this unreadable or meaningless message will raise alarm and arouse suspicionprovoking him to decrypt the message or block it from reaching the destination In either case the sender being the loser

Steganography

In Greek steganos means ldquocoveredrdquo graphie means ldquowritingrdquo

The art of hiding information in ways that prevent detection of hidden messages

SteganographyIt is the art of hiding information in ways that prevent detection of hidden messages The goal of steganography is to conceal the very existence of a message being transmitted

The idea is to hide the secret message in an ldquoenveloperdquo or ldquowrapperrdquo The envelope may be a text file an image or a sound file

embed text in textimagessound files embed image in textimagesound files embed sound in textimagesound files

The stegnosystem consists of a cover medium in which the message is hidden based upon a secret key which is known only to the sender and receiver The Stego-data output from the system has no visible distortion (in case of image) or audible distortion (in case of audio) and appears to be the same as the cover Any output which shows firsthand distortion violates the goal of steganography and cannot be used for secret communication

Key

Goals of Steganography Communicate secretly

Mike wants to send a message to Bob without Willie knowing about it

Idea is to hide the secret message in an ldquoenveloperdquo or ldquowrapperrdquo

Message must not alter the wrapper appreciably

Medium supported

What to hidendash Textsndash Imagesndash Sound

1048698 How to hidendash embed text in textimagessound filesndash embed image in textimagesound filesndash embed sound in textimagesound files

Apparently neutralrsquos protest is thoroughly discounted and ignored Isman hard hitBlockade issue affects pretext for embargo on by-products ejecting suets and vegetable oils

1048698 Hidden Message

- Pershing sails from NY June 1

Hiding in Text

Information Hiding in Images (Least Significant Bit method)

Data to be inserted character lsquoArsquo (10000011)

The pixels which would be selected for holding the data are chosen on the basis of the key which can be a random number

Ex 00100111 11101001 11001000

00100111 11001000 11101001 11001000 00100111 11101001

Embedding lsquoArsquo

00100111 11101000 1100100000100110 11001000 1110100011001001 00100111 11101001

+ =

8-bit (256 grayscale) images

TOP SECRET

Courtesy httpwwwcitiumicheduuprovoshtml

Sacrificing 5 bits of cover to carry 5 bits of secret image

Courtesy httpwwwcitiumicheduuprovoshtml

Stegano-system criteriaCover data should not be significantly modified ie perceptible to human perception system

Distortion cannot be eliminated so error-correcting codes need to be included whenever required

The cover Media should be large enough to accommodate the data to be embedded

Embedded data should be immune to modifications to cover

Future Aspects of Stegnography

- Genome Steganography Encoding a hidden message in a strand of human DNA

- Hiding in the disk space Hiding the data in unused or reserved space

- Hiding in network packets Hidden in packets transmitted through the Internet

Anonymous communication

Security reinforcement layer to cryptography

Defence

Avoid third party snooping

Modern day applications

Stegnography has its place in the security On its own it wonrsquot serve much but when usedas a layer of cryptography it would lead to a greater security- Far fetched applications in privacy protection and intellectual property rights protection- Research is going on in both the directionsa One is how to incorporate hidden or visible copyright information in variousmedia which would be publishedb At the same time in opposite direction researcher are working on how to detectthe trafficking of illicit material amp covert messages published by certainoutlawed groups

Conclusion

• The ldquoKeysrdquo to the Kingdom
• Contents
• Introduction
• Cryptography
• Steganography
• Steganography
• PowerPoint Presentation
• Goals of Steganography
• Medium supported
• Hiding in Text
• Information Hiding in Images (Least Significant Bit method)
• Slide 12
• Sacrificing 5 bits of cover to carry 5 bits of secret image
• Stegano-system criteria
• Future Aspects of Stegnography
• Slide 16
• Conclusion
• Slide 18