Steganography 111107140802 Phpapp02

7/29/2019 Steganography 111107140802 Phpapp02

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By

Harsh Madhani

Computer Engineering

Steganography


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cryptography

hidden

writing

A secret manner of writing, Generally, the art ofwriting or solving ciphers.

Oxford English Dictionary


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cryptology

hidden

speaking

1967 D. Kahn, Codebreakers p. xvi, Cryptology is the

science that embraces cryptography and cryptanalysis,but the term cryptology sometimes loosely designatesthe entire dual field of both rendering signals secureand extracting information from them.

Oxford English Dictionary


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Steganography

covered

writing

The art of secret (hidden) writing


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PATSAHORNYEGGSTEGANOGRAPHY


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Steganography

Art and science of communicating in a way thathides the existence of a message

signal or pattern imposed on content

persistent under transmission not encryption

original image/file is intact

not fingerprinting

fingerprinting leaves separate file describing contents


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Steganography includes the concealment ofinformation within computer files.

In digital Steganography, electroniccommunications may include steganographiccoding inside of a transport layer, such as adocument file, image file, program or protocol.

Media files are ideal for steganographictransmission because of their large size.

As a simple example, a sender might startwith an innocuous image file and adjust thecolor of every 100th pixel to correspond to aletter in the alphabet, a change so subtle thatsomeone not specifically looking for it isunlikely to notice it.
http://en.wikipedia.org/wiki/Pixelhttp://en.wikipedia.org/wiki/Pixel


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Classic techniques

Invisible ink (1st century AD - WW II)

Tatoo message on head

Overwrite select characters in printed type inpencil look for the gloss

Pin punctures in type

Microdots (WW II)

Newspaper clippings, knitting instructions,XOXO signatures, report cards,

i i


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igita teganograp y

Modern Steganography entered the world in1985 with the advent of the personalcomputer being applied to classicalSteganography problems.

Over 925 digital Steganography applicationshave been identified by the SteganographyAnalysis and Research Center.DigitalSteganography techniques include:

Concealing messages within the lowest bits ofnoisy images or sound files.

Chaffing and winnowing.
http://en.wikipedia.org/wiki/Steganography_toolshttp://en.wikipedia.org/wiki/Image_noisehttp://en.wikipedia.org/wiki/Chaffing_and_winnowinghttp://en.wikipedia.org/wiki/Chaffing_and_winnowinghttp://en.wikipedia.org/wiki/Image_noisehttp://en.wikipedia.org/wiki/Steganography_tools


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Concealed messages in tampered executablefiles, exploiting redundancy in the targetedinstruction set.

Pictures embedded in video material(optionally played at slower or faster speed).

Injecting imperceptible delays to packets

sent over the network from the keyboard. Delays in keypresses in some applications (

telnet or remote desktop software) can mean

a delay in packets, and the delays in thepackets can be used to encode data.

Imagebit-plane complexity segmentation Steganograph
http://en.wikipedia.org/wiki/Instruction_sethttp://en.wikipedia.org/wiki/Telnethttp://en.wikipedia.org/wiki/Remote_desktop_softwarehttp://en.wikipedia.org/wiki/BPCS-Steganographyhttp://en.wikipedia.org/wiki/BPCS-Steganographyhttp://en.wikipedia.org/wiki/Remote_desktop_softwarehttp://en.wikipedia.org/wiki/Telnethttp://en.wikipedia.org/wiki/Instruction_set


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Chaffing & Winnowing

Separate good messages from the bad ones

Stream of unencoded messages with signatures Some signatures are bogus

Need key to test

M0M3 M1M2 M0M3 M1M2

Alice Bob

M0M3 M1M2

Irene

? ? ? ?

OK


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Null Cipher

Hide message among irrelevant data

Confuse the cryptoanalyst


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Null Cipher



Big rumble in New Guinea.

The war oncelebrity acts should end soon.Over fourbig ecstatic elephants replicated.


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Null Cipher



Big rumble in New Guinea.

The war oncelebrity acts should end soon.Over fourbig ecstatic elephants replicated.

Bring two cases of beer.

t t


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etwor teganograp y

Network Steganography utilizes

communication protocols' control elementsand their basic intrinsic functionality.

Typical network Steganography methods

involve modification of the properties of asingle network protocol.

Moreover, it is feasible to utilize the relationbetween two or more different network

protocols to enable secret communication.These applications fall under the term inter-protocol Steganography.[14]
http://en.wikipedia.org/wiki/Steganographyhttp://en.wikipedia.org/wiki/Steganography


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Steganophony - the concealment of messages

in Voice-over-IP conversations, e.g. theemployment of delayed or corrupted packetsthat would normally be ignored by the

receiver (this method is called LACK - LostAudio Packets Steganography), or,alternatively, hiding information in unusedheader fields.
http://en.wikipedia.org/wiki/Voice-over-IPhttp://en.wikipedia.org/wiki/Voice-over-IP


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Image watermarking

Spatial domain watermarking

bit flipping color separation

Frequency domain watermarking embed signal in select frequency bands (e.g. high

frequency areas) apply FFT/DCT transform first

e.g. Digimarc

watermark should alter the least perceptible bits these are the same bits targeted by lossy image

compression software


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UV Watermarking


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Machine ID codes in laser printers

See http://www.eff.org/Privacy/printers/


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Text

Text lines shifted up/down (40 lines text

240 codes) word space coding

character encoding - minor changes to shapes

of characters


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Image Steganography

Image of a tree with asteganographically hiddenimage. The hidden image isrevealed by removing all butthe two least significant bits

of each color component and asubsequent normalization.

Image of a cat extractedfrom the tree imagebesides.
http://en.wikipedia.org/wiki/Bithttp://en.wikipedia.org/wiki/Color_componenthttp://en.wikipedia.org/wiki/Normalization_(image_processing)http://en.wikipedia.org/wiki/Normalization_(image_processing)http://en.wikipedia.org/wiki/Color_componenthttp://en.wikipedia.org/wiki/Bit


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Audio

Perceptual coding

inject signal into areas that will not be detected by humans may be obliterated by compression

Hardware with copy-protection

not true watermarking - metadata present on media DAT

minidisc

presence of copy protection mechanisms often failed to give

the media wide-spread acceptance


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Video

Coding still frames - spatial or frequency

data encoded during refresh closed captioning

visible watermarking used by most networks (logo at bottom-right)

D t E b ddi S it S h


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Data Embedding Security Schemes

One of the areas that improves

steganographic robustness is usage of a keyscheme for embedding messages.Key schemeterm means a procedure of how to use keysteganographic system based on the extentof its use. However, when the steganographicrobustness is increased a bandwidth of thewhole embedding system is decreased.

Therefore the task of a scheme selection forachieving the optimal values of thesteganographic system is not trivial.


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The first level of protection is determined only by the choice ofembedding algorithm. This may be the least significant bits

modification algorithm, or algorithms for modifying the frequency orspatial-temporal characteristics of the container. The first level ofprotection is presented in any steganographic channel.Steganographic system in this case can be represented as shown atThe First Protection Level Schemefigure.


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The second protection level of the steganographic system, as well as all levels ofprotection of the higher orders, is characterized by the use of Key (password)via steganographic modification. An example of a simple key scheme, whichprovides a second level of protection, is to write the unmodified or modifiedpassword in the top or bottom of the message; or the distribution of thepassword sign on the entire length of the steganographic channel. Such keyschemes do not affect the distribution of messages through the container and donot use a message preprocessing according to the defined key (see figure TheSecond Protection Level Scheme). This kind of steganographic systems are usedin such tasks as, for instance, adding a digital signature for proof of copyright.Data embedding performance is not changed in comparison with the fastest

approach of the first protection level usage.


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The difference between the fourth protection level scheme and thethird one is that in steganographic system there are twodistribution functions of a message within a container are used. The

first is responsible for a message samples selection according tosome function G(Q, N), and the second function F(P, L)is responsiblefor position selection in a container for message sample hiding. HereQ the size of message block to be inserted; N the size (in bits)of one sample of the message file (see figure The Fourth Protection

Level Scheme).

C d d i


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Countermeasures and detection

In computing, detection of steganographically

encoded packages is called steganalysis. Thesimplest method to detect modified files,however, is to compare them to known

originals. For example, to detect information beingmoved through the graphics on a website, ananalyst can maintain known-clean copies of

these materials and compare them against thecurrent contents of the site. Thedifferences, assuming the carrier is the same,will compose the payload.

Ste anal sis can have a two-sided a roach

l h d d h
http://en.wikipedia.org/wiki/Steganalysishttp://en.wikipedia.org/wiki/Steganalysis


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Steganalysis can have a two-sided approachthat involves detecting both artifacts andsignatures of known steganography

applications.All files on a suspect filesystemcan be hashed using a hash function and thencompared to a hash table of knownsteganography applications to show that a

particular steganography application is, orwas, present on the system at some point intime. The second step in the steganalysisprocess is to search all files on a suspect

filesystem for signatures (uniquelyidentifiable byte patterns) that act asidentifiers that are embedded as a result ofhiding the information.
http://en.wikipedia.org/wiki/Hash_functionhttp://en.wikipedia.org/wiki/Hash_tablehttp://en.wikipedia.org/wiki/Hash_tablehttp://en.wikipedia.org/wiki/Hash_function


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Difference between Cryptography andSteganography & Watermarking

Cryptography hides the content of themessage, but not the existence of themessage; steganography & watermarking hide

both the contents and existence of themessage.


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Then what is the difference between

Steganography and Watermarking?

Steganography performs message hiding such

that an attacker cannot detect the presenceof the message in the image/video/audio;watermarking hides the message such that anattacker cannot tamper with the message

contained within the image/video/audio.

A li ti


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Applications

Used in modern printers

Allegedly used by terrorists. e.g. It is allegedthat Al-Queda used Chaffing to encryptmessages at time of 9/11 and exchanging imagesvia ebay.com.

Alleged use by intelligence services: In2010, the FBI revealed that the Russian foreignintelligence uses customized steganographysoftware for embedding encrypted textmessages inside image files for certaincommunications with "illegal agents stationedabroad.

Digital Watermarking


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setec astronomy

The Conclusion

The conclusion is that in this world there arestill

too many secrets


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IT MEANS: THANK YOU

Hanky Out

Steganography 111107140802 Phpapp02

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