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International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.

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Hk3312911294

  1. 1. Rahul Joshi, Lokesh Gagnani / International Journal of Engineering Research and Applications(IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.1291-12941291 | P a g eImprove Security & Quality of Stego Image Using Proposed LSBMethodRahul Joshi1, Lokesh Gagnani21PG Student,KIRC,Kalol2Asst Prof,KIRC (I.T Department),KalolAbstractSteganography is the art of hiding thefact that communication is taking place, byhiding information in other information.In thispaper proposed method focus on improvingquality of stego image by increasing value ofPSNR and SNR with less number of LSBchanged compare to simple LSB method resultin better security. This paper also comparesresults of proposed method with simple LSB.I. INTRODUCTIONSteganography is the art and science ofinvisible communication. This is accomplishedthrough hiding information in other information,thus hiding the existence of the communicatedinformation. The word steganography is derivedfrom the Greek words “stegos” meaning “cover”and “grafia” meaning “writing” [1] defining it as“covered writing”. In image steganography theinformation is hidden exclusively in images. Todaysteganography is mostly used on computers withdigital data being the carriers and networks beingthe high speed delivery channels. Steganographydiffers from cryptography in the sense that wherecryptography focuses on keeping the contents of amessage secret, steganography focuses on keepingthe existence of a message secret [2].Steganography and cryptography are both ways toprotect information from unwanted parties butneither technology alone is perfect and can becompromised. Once the presence of hiddeninformation is revealed or even suspected, thepurpose of steganography is partly defeated [2].The strength of steganography can thus beamplified by combining it with cryptography.Research in steganography has mainly been drivenby a lack of strength in cryptographic systems.Many governments have created laws to eitherlimit the strength of a cryptographic system or toprohibit it altogether [3], forcing people to studyother methods of secure information transfer.Businesses have also started to realize the potentialof steganography in communicating trade secrets ornew product information. Avoiding communicationthrough well-known channels greatly reduces therisk of information being leaked in transit [4].Hiding information in a photograph of thecompany picnic is less suspicious thancommunicating an encrypted file.II. SIMPLE LSB METHODAlgorithmThe popular and oldest method for hiding themessage in a digital image is the LSB method. InLSB method we hide the message in the leastsignificant bits (LSB’s) of pixel values of an image.In this method binary equivalent of the secretmessage is distributed among the LSBs of eachpixel.For example data bits 01100101 are tried to hideinto an 8 bit image. According to this technique 8consecutive pixels from top left corner of the imageare selected. The binary equivalent of those pixelsmay be like this:00100101 11101011 11001010 0010001111111000 11101111 11001110 11100111Now each bit of data 01100101 are copied serially(from left hand side) to the LSB’s of equivalentbinary pattern of pixels, resulting the bit patternwould become:00100100 11101011 11001011 0010001011111000 11101111 11001110 11100111The problem with this technique is that it is veryvulnerable to attacks such as image compressionand quantization of noise.III PROPOSED LSB METHODAlgorithm-Hiding Operation
  2. 2. Rahul Joshi, Lokesh Gagnani / International Journal of Engineering Research and Applications(IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.1291-12941292 | P a g e.Algorithm-Extracting OperationIn this method message bits divide intosegment using proper segment length ( like 2,4,8etc). Create the segments in such a way that consistequal number of bits in each segment. Selectsuitable cover image enough to embed entiremessage. For testing purpose I use bmp type imageof 8 bit depth. Store segments into one list calledsegment list. Find all lsb of cover image and storeinto one dimensional array called imagebits. Nowfind the best match sequence of lsb in one segmentwith sequence of imagebits. If match is found thenreplace that sequence of lsb with message bits ofsegment. If match is not found then insert messagebits into lsbs without overlapping the sequence oflsb .Repeat this process for all segments.Resultant image is called stego image. To extractmessage follow algorithm for extracting operation.IV.EXPERIMENTAL PARAMETERa) .Number of LSB changedThis parameter count the number of lsb changed.For better result value of this parameter keep asminimum as possibleb). TimeThis parameter use to measure time required tohide message in image and also time required toretrieve message from image.c). Signal to Noise RatioSNR is calculate using following equationSignal-to-noise ratio expressed in dBd).Peak Signal to Noise RatioPeak signal-to-noise ratio expressed in dBPSNR is the standard measurement used insteganography technique in order to test the qualityof the stego images. Higher the value of PSNRmore the quality of the stego image.V. EXPERIMENTAL RESULTAfter implementation of Simple andProposed LSB method for lena.bmp androcket.bmp in Matlab (R2009a) following resultsare obtained. Here both images have 8 bit depth.Following Table shows the result of both methodsfor lena.bmp
  3. 3. Rahul Joshi, Lokesh Gagnani / International Journal of Engineering Research and Applications(IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.1291-12941293 | P a g eFollowing Table shows the result of both methodsfor rocket.bmpFollowing Figures ( a to d) Shows the effect ofsegment length on various parameters forlena.bmp(a)(b)(c)(d)Following Figures (e to h) shows the effect ofsegment length on various parameters forrocket.bmp(e)
  4. 4. Rahul Joshi, Lokesh Gagnani / International Journal of Engineering Research and Applications(IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.1291-12941294 | P a g e(f)( g)(h)Figure (a,e) shows the effect of segment length (for2,4,5) on number of LSB changed. As length ofsegment is increase number of LSB changed alsoincrease because probability of finding matchsequence is decrease as length of segment isincrease.Figure (b,f) shows the effect of segment length (for2,4,5) on SNR. As length of segment is increasevalue of SNR is decrease due to number of LSBchanged increase. This is also true for rocket.bmpFigure (c,g) shows the effect of segment length (for2,4,5) on PSNR. As length of segment is increasevalue of PSNR is decrease due to number of LSBchanged increase.Figure (d,h) shows the effect of segment length (for2,4,5) on Time required to hide message in image.As length of segment is increase time required tohide message is decrease because number ofsegments is decrease .so time spend to searchmatch sequence is also reduced.VI CONCLUTIONThe main purpose of this method is todecrease the number of LSB that are changed andas a result increase the immunity of the stego-image against the attack by human visual system(HVS). The problem of the proposed LSB Methodis time required to hiding message that is spendduring the search to find the best matching whenusing a large size stego-image. Implementation ofthis method for Audio and Video Steganographywill considered as a future work.REFERENCES[1] Moerland, T., “Steganography andSteganalysis”, Leiden Institute ofAdvanced Computing Science,www.liacs.nl/home/ tmoerl/privtech.pdf[2] Wang, H & Wang, S, “Cyber warfare:Steganography vs. Steganalysis”,Communications of the ACM, 47:10,October 2004[3] Dunbar, B., “Steganographic techniquesand their use in an Open-Systemsenvironment”, SANS Institute, January2002[4] Artz, D., “Digital Steganography: HidingData within Data”, IEEE InternetComputing Journal, June 2001

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