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An Efficient Data Hiding Technique using Image Steganography

Jun 04, 2018

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    An Efficient Data HidingTechnique using Image

    Steganography

    Presented By:

    Jayesh Bhardwaj (BE/1124/07)

    Manish Kumar (BE/1132/07)

    Kapil Ratra (BE/1123/07)

    Project Guide:

    V.S.S Sriram

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    Introduction to Steganography:

    Steganography is the technique of concealment of data withinanother data medium so that it is very difficult to even detect the

    presence of hidden data.

    For example, We have two images below and it is amazing to knowthat the second image was hidden in the first image. This is the alsoknown as image steganography.

    Cover image Stego image

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    CoverImage->stego-image

    How?

    Drop all but the last 2 bitsof each color componentin each pixel

    Enhance brightness 85x

    2 MSB

    110000

    111100

    11

    00

    Become

    2LSB

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    Basic Techniques in Image

    Steganography: Lsb Steganography: This is the most basic

    and one of the easiest to implement methods in

    image steganographybut is now rarely used inits primitive form due to the ease with which itcan be cracked using basic steganalysistechniques.

    In this method we embed one bit of the data tohide in each pixel of the image (in the LSB)which results in insignificant distortion.

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    DCT based image steganography: This isone of the basic techniques in which we use theDiscrete Cosine Transform of the image to hide

    the data in the image medium. In this method the image is broken into blocks of

    88 and DCT is calculated for each of them.While retaining the coefficients of the high

    frequency terms the lower frequency terms areinstead used for the data to be hidden. Then weapply IDCT to the blocks to get the stego+coverimage. The recovery of image is done by simplythe reversal of the above steps.

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    Problems with the basic

    techniques: These basic techniques are vulnerable to the

    basic steganalysis methods owing to theirsimplicity.

    LSB method is not suitable when we use imagemanipulation technique such as imagecompression etc. DCT method can be applied insuch cases.

    Often mapping algorithms are used with the LSBmethod to map the bits of the stego to the bytesof the cover image in a non-linear manner.

    But inclusion of a data structure such as a mapincreases the space complexity.

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    With the rising demand for a secure medium of datatransfer cryptographic techniques were combined withthe steganography methods. i.e Symmetric Key

    Cryptography. Due to the limitations on bandwidth the steganography

    mechanism should be space as well as time efficient.

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    Goal of Design:

    To develop an efficient steganography method ourdesign should be resistive to the basic steganalysismethods.

    Our design should be space efficient i.e should consumeminimum memory.

    The design should be time efficient i.e the mechanismshould take minimum cpu time.

    The design should be such that even if an intruderknows about the presence of concealed data it is almostimpossible for him to extract the stego data.

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    Block Diagram Steganography

    Encoder

    Decoder

    Cover

    Image

    Secret

    Text

    Key

    Stego

    Object

    Original

    Cover

    Secret

    Text Communication

    s Channel

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    The Proposed Algorithm:

    The algorithm uses a combination of the LSB techniqueand a method similar to private key cryptography.

    A key is associated with each stego data and should be

    available with both the sender and the receiver. The key is used as a seed in our random number

    generator function. The generated random number is used to circular rotate

    each of the bytes of the stego data. i.e the first byte ofstego data is right rotated n mod 8 times where n is therandom number. Now this number is passed as seed togenerate a new random number for the second byte andso on.

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    After all the bytes have been rotated as per the

    generated random numbers we start embedding thestego data bit by bit in the LSB of each pixel. The random number generator function is designed such

    that it generates the same sequence of random numbersif same seed is provided which is crucial for the recovery

    process. During recovery of data at receiver side we first extract

    the LSB of the all the bytes of the received image. After extracting all the LSBs we use the same seed to

    generate the same sequence of random numbers andnow use them to rotate the byte in left direction (or right ifleft was used by sender).

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    Pseudocode:

    //Sender SideKey k;//Rotation codeFor each Byte in stego: k=myrand(k); right_rotate(Byte,k%8);//EmbeddingStegobit=first bit of stegoFor each Byte in cover image:

    embed in lsb of Byte the stegobit move stegobit to next bit

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    Pseudo Code Contd.

    //Receiver SideKey k; //same key as sender//ExtractStegobit=For each Byte in recvd_image: extract lsb from Byte append lsb to stegobit//RotateFor each Byte in Stegobit:

    k=myrand(k); left_rotate(Byte,k%8);//Extraction Complete

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    Analysis of Algorithm:

    8n

    Lets analyse the difficulty in breaking this code: The intruder can extract the lsb from the cover image but the data

    when assembled seems unarguably random and is meaninglesssince each byte of the data is rotated. If he uses guess work toderive the correct number of rotation for each pixel he would needcalculations where n is the number of pixels.

    Thus it becomes very difficult for computing systems with ordinarycomputing resources to successfully extract the data from theintercepted image.

    The code is pretty simple in implementation and hence consumes

    very less computing resources.

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    Waveform Steganography

    Steganography in waveforms means embedding thestego data in the waveforms so that the new

    waveform formed after embedding is almost same asprevious one. This is a new way of hiding a data inwaveforms. It can be highly useful in fields ofmedicine for hiding the patients data in his/her ECG

    report, military for sending secret information in thetopography maps, education for hiding studentsinformation in his performance graph ,etc.

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    Input Sampled Waveform

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    Output Sampled Waveform

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    Video Steganography

    Video files are generally a collection of images and sounds, somost of the presented techniques on images and audio can beapplied to video files too. The great advantages of video are the

    large amount of data that can be hidden inside and the fact that it

    is a moving stream of images and sounds. Therefore, any small

    but otherwise noticeable distortions might go by unobserved by

    humans because of the continuous flow of information.

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    Implementation for Video files:

    The algorithm was implemented onVideo files with some minor

    modifications. We need to extract frames from the

    video files and apply image

    steganography techniques on them. At receiver end to we extract those

    frames which contain stego data.

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    Simulation of Algorithm on

    Video Files:

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    References:

    Neil F. Johnson, Sushil Jajodia, George Mason University,"Exploring Steganography: Seeing the Unseen", IEEE Computers,February 1998, pp. 26-34

    Neil F. Johnson, Sushil Jajodia, Center for Secure InformationSystem, George Mason University, "Steganalisys of Images CreatedUsing Current Steganography Software", http://isse.gmu.edu/~csis

    Alexander Herringel, Joseph Ruanaidh, Holger Petersen, Shelby

    Pereira, Thierry Pun, "Secure Copyright Protection Techniques for

    Digital Images", 2nd Information Hiding Workshop, 1998 Ross J. Anderson, Fabien A.P. Petitcolas, "On the limits of

    steganography"

    Designing of Robust Image Steganography Technique Based onLSB Insertionand Encryption Mamta Ju

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