基于整数小波变换和双三次插值的隐写术(IJIGSP-V4-N12-4)

I.J.Image,GraphicsandSignalProcessing,2012,12,26-33PublishedOnlineNovember2012inMECS()DOI:10.5815/ijigsp.2012.12.04Copyright©2012MECSI.J.Image,GraphicsandSignalProcessing,2012,12,26-33SteganographyBasedonIntegerWaveletTransformandBicubicInterpolationN.AjeeshvaliM.Techstudent,DepartmentofElectronicsandcommunicationengineering,GudlavalleruEngineeringCollege,GudlavalleruJawaharlalNehruTechnologicalUniversityKakinada,KakinadaE-mail:[e-mail]ssor,DepartmentofElectronicsandCommunicationEngineering,GudlavalleruEngineeringCollege,GudlavalleruJawaharlalNehruTechnologicalUniversityKakinada,KakinadaE-mail:[e-mail]—Steganographyistheartandscienceofhidinginformationinunremarkablecovermediasoasnottoobserveanysuspicion.Itisanapplicationunderinformationsecurityfield,beingclassifiedunderinformationsecurity,Steganographywillbecharacterizedbyhavingsetofmeasuresthatrelyonstrengthsandcounterattacksthatarecausedbyweaknessesandvulnerabilities.Theaimofthispaperistoproposeamodifiedhighcapacityimagesteganographytechniquethatdependsonintegerwavelettransformwithacceptablelevelsofimperceptibilityanddistortioninthecoverimageasamediumfileandhighlevelsofsecurity.Bicubicinterpolationcausesovershoot,whichincreasesacutance(apparentsharpness).TheBicubicalgorithmisfrequentlyusedforscalingimagesandvideofordisplay.Thealgorithmpreservesfinedetailsoftheimagebetterthanthecommonbilinearalgorithm.IndexTerms—Steganography,IntegerWaveletTransform(IWT),OptimalPixelAdjustmentProcess(OPAP),BicubicinterpolationI.INTRODUCTIONTheinformationcommunicatedcomesinnumerousformsandisusedinpeertopeercommunicationnetworksanddigitalcommunications.Steganographyisatypeofhidingthecommunicationdatathatmeans―coveredwriting‖obtainedfromtheGreekwordssteganoor―covered‖andgraphosor―towrite‖.ThegoalofSteganographyistohideaninformationmessageinsideharmlesscovermediuminsuchawaythatitisimpossibleeventodetectthatthereisasecretmessage[1,2].Theinformationdata-hidingprocessinaSteganographicsystemstartsbyidentifyingacovermedium‘sredundantbits(thosethatcanbemodifiedwithoutdestroyingthatmedium‘sintegrity).Theembeddingprocessproducesastegomediumbyreplacingtheseredundantbitswithdatafromthehiddenmessage.Suchsecretcommunicationrangesfromthecasesofbanktransfers,corporatecommunications,andcreditcardpurchases,alargepercentageofeverydaymail.MainlySteganographyaimistokeepitspresenceundetectable,butsteganographicsystems,becauseoftheirnature,leavesdetectabletracesinthecovermediumfile.Modifyingitsstatisticalproperties,anyonecandetectthedistortionsintheresultingstegomedium‘sstatisticalproperties.Theprocesscalledstatisticalsteganalysisisusedtofindthedistortionsoccurred.II.STEGANOGRAPHYSYSTEMAsteganographicsystem‘ssecurityisdependentontheencodingsystem‘ssecrecy.Althoughsuchasystemmightworkforatime,itissimpletoexposetheentirereceivedmedialikeimagesarepassingbytocheckforhiddenmessages;suchasteganographicsystemmaybefails.Modernsteganographicsystem,asshowninFigure1attemptstobedetectableonlyifsecretinformationisknownnamely,asecretkey[1].Inthisprocess,cryptographyshouldbeused,whichholdsthatacryptographicsystem‘ssecurityshoulddependantsolelyonthekeymaterial.Steganographytoremainundetected,theunmodifiedcovermediumbykeepingsecret,ifitisexposed,acomparisonbetweenthecoverandstegomediaimmediatelydescribesthechanges[4,6].Thebasictypesofstegosystemsareavailableunderthreemodels:•Purestegosystems-nokeyisusedforthesystem.•Secret-keystegosystems–hereaprivatekeyisused.•Public-keystegosystems–inthispublickeyisused.ThetechniquethatisfollowedinthispaperwillusesecretkeytoencryptthehiddenmessagethatwillbeencapsulatedinsideacovermediaSteganographyBasedonIntegerWaveletTransformandBicubicInterpolation27Copyright©2012MECSI.J.Image,GraphicsandSignalProcessing,2012,12,26-33.Figure1.SteganographysystemA.Information-hidingsystemfeaturesAninformation-hidingsystemischaracterizedbehavingthreedifferentaspectsthatcontendwitheachotherarecapacity,security,androbustness.Capacityreferstotheamountofinformationthatcanbehiddeninthecovermedium,securitytoaneavesdropper‘sinabilitytodetecthiddeninformation,androbustnesstotheamountofmodificationthestegomediumcanwithstandbeforeanadversarycandestroyhiddeninformation[6].B.DatahidingtechniquesThemostpopularhidingtechniquesarespatialdomainandtransformdomainbasedtechniques.ThefirstgroupisbasedonembeddingmessageintheLeastSignificantBits(LSB)ofimagepixels.Ithaslowrobustnessversussomeattackssuchaslow-passfilteringandcompression[5].SpatialdomainbasedsteganographyincludestheLeastSignificantBit(LSB)technique[3];PixelvaluedifferencingandlaterincludesDCT,DWTandIWT.SeveralsteganographytechniquesfordatahidinginJPEGhavebeenproposed;suchasJ-Steg[7],JPHide&Seek[7]andOut-Guess[8].MostrecentresearchesutilizeDiscreteWaveletTransform(DWTbecauseofitswideapplicationinthenewimagecompressionstandard,JPEG2000.AnexampleistheemploymentofanadaptivedataembeddingtechniquewiththeuseofOPAPtohidedatainIntegerWaveletcoefficientsofthecoverimage[9].III.THES