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On the Information Hiding Technique Using Least Significant Bits Steganography

Jun 04, 2018

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    (IJCSIS) International Journal of Computer Science and Information Security,Vol. 11, No. 11, 2013

    On the Information Hiding Technique Using LeastSignificant Bits Steganography

    Samir El-Seoud

    Faculty of Informatics and Computer Science,The British University in Egypt,Cairo, Egypt

    Islam Taj-Eddin

    Faculty of Informatics and Computer Science,The British University in Egypt,Cairo, Egypt

    Abstract Steganography is the art and science of hiding data orthe practice of concealing a message, image, or file within anothermessage, image, or file. Steganography is often combined withcryptography so that even if the message is discovered it cannotbe read. It is mainly used to maintain private data and/or secureconfidential data from misused through unauthorized person. Incontemporary terms, Steganography has evolved into a digitalstrategy of hiding a file in some form of multimedia, such as an

    image, an audio file or even a video file. This paper presents asimple Steganography method for encoding extra information inan image by making small modifications to its pixels. Theproposed method focuses on one particular popular technique,Least Significant Bit (LSB) Embedding. The paper uses the(LSB) to embed a message into an image with 24-bit (i.e. 3 bytes)color pixels. The paper uses the (LSB) of every pixels bytes. Thepaper show that using three bits from every pixel is robust andthe amount of change in the image will be minimal andindiscernible to the human eye. For more protection to themessage bits a Stego-Key has been used to permute the messagebits before embedding it. A software tool that employsteganography to hide data inside of other files (encoding) as wellas software to detect such hidden files (decoding) has beendeveloped and presented.

    Key Words Steganography, H idden-D ata, Embedding-Stego- M edium, Cover-M edium, D ata, Stego-Key, Stego-I mage, LeastSignif icant Bit (L SB), 24-bit color pixel, Hi stogram Er ror (H E),Peak Signal N oise Ratio (PSNR), Mean Square Er ror (M SE).

    I. I NTRODUCTIONOne of the most important properties of digital

    information is its easiness in producing and distributingunlimited number of its copies (i.e. copies of text, audio andvideo data) regardless of the protection of the intellectualand production rights. That requires innovative ways ofembedding copyright information and serial numbers in thosecopies.

    Nowadays, the need for private and personal computercommunication for sharing confidential information

    between two parties has increased.

    One such technique to solve the above mentioned problems is Steganography [11][3]. It is the art of hiding private information in public information used or sent on public domain or communication from an unwanted party.

    These private information need to be undetectable and/orirremovable, especially for the audio and video data cases.

    The art of hiding messages is an ancient one.Steganography (literally meaning covered writing ) is a form ofsecurity through obscurity. For example, a message might

    be hidden within an image. One method to achieve that is by

    changing the least significant bits to be the message bits. Theterm steganography was introduced at the 15th century.Historically, steganography was used for long timeago. Messages were hidden (i.e. tattooed) on the scalp ofslaves. One famous example being Herodotus who in hishistories tells how Histiaeus shaved the head of his mosttrusted slave and tattooed it with a message which disappearedonce the hair grew back again. Invisible ink has been for quitesome time. Microdots and microfilm technology used after theadvance of the photography science and technology.

    Steganography hides the private message but not the factthat two parties are communicating. The process involves

    placing a hidden message in a transport medium (i.e. thecarrier). The secret message is embedded in the carrier to formthe steganography medium. Steganography is generallyimplemented by replacing bits of data, in regular computerfiles, with bits of different, invisible information. Thosecomputer files could be graphics, sound, text or HTML. Thehidden information can be plain text, cipher text, or images.

    In paper [2], the authors suggested an embeddingalgorithm, using two least significant bits that minimize thedifference between the old value of the pixel in the cover andthe new value of the pixel in the stego-image in order tominimize the distortion made to the cover file. Experimentalresults of the modified method show that PSNR is greater thanthe conventional method of LSBs replacement.

    A distinguish between stegnography and cryptographyshould be emphasized. Steganography is the science and artof hiding information from a third party.Cryptography is the science and art of making dataunreadable by a third party. Cryptography got more attentionfrom both academia and industry than steganography.

    34 http://sites.google.com/site/ijcsis/ISSN 1947-5500

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    (IJCSIS) International Journal of Computer Science and Information Security,Vol. 11, No. 11, 2013

    Nowadays, steganography is becoming increasingly importantfor both military and commercial communities [9].

    II. STEGANALYSIS Steganalysis is the science and art of detecting and

    breaking steganography. Examining the color palette is onemethod of the steganalysis to discover the presence of hiddenmessage in an image. Generally, there will be a unique binaryencoding of each individual color. If the image containshidden data, however, many colors in the palette will haveduplicate binary encodings. If the analysis of the color

    palette of a given image yields many duplicates, we mightconclude with high confidence of the presence of hiddeninformation.

    Steganalysts have a tough job to do, because of the vastamount of public files with different varieties (i.e. audio,

    photo, video and text) they have to cover. Different varietiesrequire different techniques to be considered.

    Steganalysis and cryptanalysis techniques can be

    classified in a much similar way, depending upon the known prior information:

    Steganography-only attack: Steganography medium isavailable and nothing else.

    Known-carrier attack: Carrier and steganography mediaare both available.

    Known-message attack: Hidden message is known. Chosen-steganography attack: Steganography medium

    as well as used steganography algorithm are available. Chosen-message attack: A known message and

    steganography algorithm are used to createsteganography media for future analysis.

    Known-steganography attack: Carrier andsteganography medium, as well as thesteganography algorithm, are available.

    In [1] the author urges the steganalysis investigation of thethree least significant bits.

    Until recently, information hiding techniques received verymuch less attention from the research community and fromindustry than cryptography, but this has changed rapidly. Thesearch of a safe and secret manner of communication is veryimportant nowadays, not only for military purposes, but alsofor commercial goal related to the market strategy as well

    as the copyright rights.

    Steganography hides the covert message but not the factthat two parties are communicating with each other. Thesteganography process generally involves placing a hiddenmessage in some transport medium, called the carrier. Thesecret message is embedded in the carrier to form thesteganography medium. The use of a steganography key may

    be employed for encryption of the hidden message and/or forrandomization in the steganography scheme.

    III. HOW DOES IT WORK ?Without any loss of generality, the paper will use the

    following equation to support us with a general undurstandingof the steganographic process:

    cover_medium + hidden_data + stego_key = stego_medium.

    The cover_medium is the file to be used to hide thehidden_data. A stego_key could be used if an encryptionscheme (i.e. private/public key cryptography) will be mixedwith the steganography process. The resultant file is thestego_medium, which will be the same type of file as thecover_medium. In this paper, we will refer to thecover_image and stego_image, because the focus is on theimage files.

    Classification of stenography techniques based on the cover

    modifications applied in the embedding process is as follows: A. Least significant bit (LSB) method

    This approach [19][6][5][4][14][12] is very simple. In thismethod the least significant bits of some or all of the bytesinside an image is replaced with a bits of the secretmessage. The least significant bit (LSB) substitution andmasking & filtering techniques are well knowntechniques to data hiding in images. LSB is a simpleapproach for embedding information in an image.Replacement of LSBs in digital images is an extremely simpleform of information hiding.

    B. Transform domain techniquesThis approach [7][10] embeds secret information in the

    frequency domain of the signal. Transform domain methodshide messages in significant areas of the cover image whichmake them more robust to attacks such as: compression,cropping, and some image processing, compared to LSBapproach.

    C. Statistical methodsThis approach [8] encodes information by changing

    several statistical properties of a cover and uses ahypothesis testing in the extraction process. The above processis achieved by modifying the cover in such a way that somestatistical characteristics change significantly i.e. if "1" is

    transmitted then cover is changed otherwise it is left as such.

    D