Steganography

Steganography

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  The “Keys” tothe Kingdom Presented By: Mustahid ali
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  Contents Communication? What is cryptography? Whatis steganography? Steganography in digital images
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  Introduction Communication has alwaysbeen 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 globe.Whenever there is a communication link there has always been a “Recipient” for whom the message is meant and a “Sender” who is sending the message. But as is always the case there is a third person called “The Miscreant” or the “Intruder” 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 ‘i’ and ‘j’ • Deliberate misspellings or Error • Writing with invisible ink
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  Cryptography: It is theprocess 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 suspicion,provoking him to decrypt the message or block it from reaching the destination. In either case the sender being the loser.
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  Steganography In Greek steganosmeans “covered” graphie means “writing”. The art of hiding information in ways that prevent detection of hidden messages.
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  Steganography: It is theart 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 “envelope” or “wrapper”. The envelope may be a text file, an image or a sound file. • embed text in text/images/sound files • embed image in text/image/sound files • embed sound in text/image/sound 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.
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  Key
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  Goals of Steganography Communicatesecretly Mike wants to send a message to Bob without Willie knowing about it. Idea is to hide the secret message in an “envelope” or “wrapper”. Message must not alter the wrapper appreciably.
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  Medium supported What tohide – Texts – Images – Sound • How to hide – embed text in text/images/sound files – embed image in text/image/sound files – embed sound in text/image/sound files
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  Hiding in Text: Apparentlyneutral’s protest is thoroughly discounted and ignored. Isman hard hit.Blockade issue affects pretext for embargo on byproducts, ejecting suets and vegetable oils • Hidden Message - Pershing sails from NY June 1
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  Information Hiding inImages: (Least Significant Bit method) Data to be inserted: character ‘A’: (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 11001000 00100111 11101001 11101001 Embedding ‘A’ 00100111 00100110 11001001 11101000 11001000 00100111 11001000 11101000 11101001
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  TOP SECRET + = 8-bit (256grayscale) images. Courtesy: http://www.citi.umich.edu/u/provos.html
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  Sacrificing 5 bitsof cover to carry 5 bits of secret image Courtesy: http://www.citi.umich.edu/u/provos.html
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  Stegano-system criteria Cover datashould not be significantly modified i.e 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.
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  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.
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  Modern day applications Anonymouscommunication Security reinforcement layer to cryptography Defence Avoid third party snooping
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  Conclusion Stegnography has itsplace in the security. On its own, it won’t serve much but when used as 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 directions a. One is how to incorporate hidden or visible copyright information in various media, which would be published. b. At the same time, in opposite direction, researcher are working on how to detect the trafficking of illicit material & covert messages published by certain outlawed groups