图像信息隐藏算法的研究与实现翻译.docx

图像信息隐藏算法的研究与实现翻译.docx

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图像信息隐藏算法的研究与实现翻译

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苏州大学应用技术学院11电子班（学号**********）马玲丽

ImageInformationHiding:

AnSurvey

I.INTRODUCTION

Nowadaysmanyproblemsariseduringtheimagetransformationfromthesendertothereceiver.Strangerscaneasilysnoopintoothersaccountandgetmanysecretinformationevenitwashidedbysomemechanism,withouttheirpermission.Toavoidthisweproposeasecureschemebyusingsteganographyconcept.Steganographymeanshidinginformationinaparticularwaythatpreventsthedetectionofhiddeninformation.Inthisconceptnoonecanfindthatthereisahiddenmessagepresentintheimage,Becauseofinformationishiddenbehindanimageinamatrixform,whichiscreatedbybitmatrixoftheobject.ByusingtheLSBwecanstorethecharacteristicsofparticularpixelsofanimagearemodifiedtostoreamessage.Finallywesendthefinalpictureandcoverimageusedforhiddentheimagetothereceiver[Johnson&Jajodia,1998].

Atfirstwecalculatetheheightandwidthoftheimage,whichhidetheinformationthenmultiplyitwith8andstoreitinanyvalue.Thenwecalculatetheheightandwidthoftheimagewhichisusedtohidetheobjectandmultiplywitheachother.Thenwecomparethatanswerswithboththeimagewhichisusedtohidetheinformationandwhichisusedtohidetheobject.Theimagewhichisusedtohidetheobjectmusthavegreatervaluethantheotherimage;wechoosetheobjectmustsatisfytheabovecondition.Thentheencodedmatrixismappedwiththeimagebyusingleastsignificantbitmechanism.

Leastsignificantbitonlystorestheinformationinsteadofreplacingthepixelofimage.Soscatteringofinformationtakesplacewhiletransferringtheimagesoaccordingtohumaneyethereisnodifferencebetweentheoriginalandstegoimage.Finallysendersendsthebothoriginalandstegoimagetothereceiver.InthereceiversidetogettheinformationthereceivermustdoXORoperationbetweenbytespresentinboththeimage.Comparetheresultwith0*00000000Iftheoutputwillbeyesthenstore0else1inamatrixandthismatrixwillbeequaltothewidthandheightofthepixelmatrixoftheimage.Convertthebitsintobytesuntilallbitsgotutilized.Finallyreceivergetstheinformation.

1.1.HistoryofInformationHiding

1.2.TheBasicsofEmbedding

Threedifferentaspectsininformation-hidingsystemscontendwitheachother:

capacity,security,androbustness.Capacityreferstotheamountofinformationthatcanbehiddeninthecovermedium,securitytoaneavesdropper’sinabilitytodetecthiddeninformation,androbustnesstotheamountofmodificationthestegomediumcanwithstandbeforeanadversarycandestroyhiddeninformation[FabienA.P.Petitcolasetal.,1999;SabuMThampi,2004;NameerN.EL-Emam,2007].

1.3.DiscreteCosineTransform

Foreachcolorcomponent,theJPEGimageformatusesaDiscreteCosineTransform（DCT）totransformsuccessive8×8pixelblocksoftheimageinto64DCTcoefficientseach.TheDCTcoefficientsF（u,v）ofan8×8blockofimagepixelsf（x,y）.

Asimplepseudo-codealgorithmtohideamessageinsideaJPEGimagecouldlooklikethis:

Input:

message,coverimage

Output:

steganographicimagecontainingmessage

Whiledatalefttoembeddo

GetnextDCTcoefficientfromcoverimage

IfDCT=!

0andDCT=!

1then

GetnextLSBfrommessage

ReplaceDCTLSBwithmessagebit

Endif

InsertDCTintosteganographicimage

Endwhile

1.4.DetectionTechniques

Manyalgorithmswereproposedforestimatingthelengthofthesecretmessageinthecoverimage.Westfeld（2001）proposedtheblindsteganalysisbasedonstatisticalanalysisofPoVs（pairsofvalues）.Thismethod,so-calledstatisticaltest,givesasuccessfulresulttoasequentialLSBsteganographyonly.Fridrichetal.proposedtheRSsteganalysis.Thismethodmakessmallalternationstotheleastsignificancebitplaneinanimagethebyusingthefollowingmethodourprocess[Kekreetal.,2008;BinLietal.,2011].

1.5.SecuritythePacketDecoder

Thedecodeengineisorganizedaroundthelayersoftheprotocolstackpresentinthesupporteddata-linkandTCP/IPprotocoldefinitions.Eachsubroutineinthedecoderimposesorderonthepacketdatabyoverlayingdatastructuresontherawnetworktraffic.Thesedecodingroutinesarecalledinorderthroughtheprotocolstack,fromthedatalinklayerupthroughthetransportlayer,finallyendingattheapplicationlayer.Speedishighlightinthissection,andthemajorityofthefunctionalityofthedecoderconsistsofsettingpointersintothepacketdataforlateranalysisbythedetectionengine[RichardPopa,1998].

1.6.InternetProtocolVersion

InternetProtocolversion6（IPv6）isanetworklayerIPstandardusedbyelectronicdevicestoexchangedataacrossapacket-switchedinternetwork.ItfollowsIPv4asthesecondversionoftheInternetProtocoltobeformallyadoptedforgeneraluse.AmongtheimprovementsbroughtbyIPv6istheincreaseofaddressesfornetworkeddevices,allowing,forexample,eachcellphoneandmobileelectronicdevicetohaveitsownaddress.IPv4supports4.3×109（4.3billion）addresses,whichisinadequateforgivingevenoneaddresstoeverylivingperson,muchlesssupporttheburgeoningmarketforconnectivedevices.IPv6supports3.4×1038addresses,or5×1028（50octillion）foreachoftheroughly6.5billionpeoplealivetoday.

Normallythepacketsaretransferredfromonesystemtoanotherinpackets.Thepacketsaretransferredthroughthetcpconnectioninamoresecureway.

II.HIDEANDSEEK:

ANINTRODUCTIONTOSTEGANOGRAPHY

2.1.ProblemFormulation

Inthepast,forthesecuritypurposepeopleusedhiddentattoosorinvisibleinktoconveysteganographiccontent.Todayforhidingpurposecomputerandnetworktechnologiesprovideeasy-to-usecommunicationchannelsforsteganography[SarajuP.Mohant,2003;MuhalimMohamedAminetal.,2003].

Steganographicsystembecauseoftheirinvasivenature,leavethedetectabletracesinthecovermedium.Thesecretcontentisnotrevealed,butitsstatisticalpropertieschangedsothethirdpartycandetectthedistortionsintheresultingimage[Morkeletal.,2005].Theprocessoffindingthedistortionsiscalledstatisticalsteganalysis.

2.2.ResearchDesign

Thispaperexplainsthesteganagraphicsystemsandpresentstherecentresearchindetectingthemthroughstatisticalsteganalysis.

SteganographicsystemsfortheJPEGformatseemmoreinteresting,becausethesystemsoperateinatransformspaceandarenotaffectedmyvisualattacks.

Visualattacksmeanthatwecanseesteganographicimagesonthelowbitplanesofanimagebecausetheyoverwritethevisualstructures.

2.3.Finding

TheJPEGimageformatusesadiscretecosinetransformtotransformsuccessive8*8pixelblocksoftheimageinto64DCTcoefficientseach.TheSIJTransactionsonComputerScienceEngineering&itsApplications（CSEA）,Vol.1,No.1,March-April2013ISSN:

2321–2381©2013|PublishedbyTheStandardInternationalJournals（TheSIJ）3

TheembeddingalgorithmsequentiallyreplacestheleastsignificantbitofDCTcoefficientswiththemessagedata.ThesameprocessisalsodoneintheJPEGformat.

Theauthorandhiscolleagueusedasupportvectormachinetocreateanonlineardiscriminationfunction.Thentheypresentalesssophisticatedbuteasiertounderstandmethodfordeterminingalineardiscriminationfunction.

2.4.ConclusionandLimitations

Weofferfourdetailsforourinabilitytofindsteganographiccontentontheinternet.Theyare,

·Allsteganographicsystemuserscarefullychoosepasswordsthatarenotsusceptibletodictionaryattacks.

·Maybeimagesfromsourceswedidnotanalyzecarrysteganographiccontent.

·Nobodyusessteganographicsystemsthatwecouldfind.

·Allmessagesaretoosmallforouranalysistodetect.

Althoughsteganographyisapplicabletoalldataobjectsthatcontainredundancy,weconsiderJPEGimagesonlyforsteganography.

2.5.Implications

Weinsertthetracerimagesintoeverystegbreakjob.Thedictionaryattackfollowsthecorrectpasswordsfortheseimages.

III.STEGANOGRAPHYANDSTEGANALYSIS

3.1.ProblemFormulation

Thegrowthofcomputernetworksandinternethasexploredmeansofbusiness,scientific,entertainment,andsocialopportunities.

Thedigitalinformationcanbeeasilyduplicatedanddistributedhasledtotheneedforeffectivecopyrightprotectiontoolssuchassteganographyandcryptography[StefanoCacciaguerra&StefanoFerretti,2003;RobertKrenn,2004].

3.2.ResearchDesign

Secretscanbehiddeninsideallsortsofcoverinformation:

text,images,audio,videoandmore.Moststeganographicutilitiesnowadays,hideinformationinsideimages,asthisisrelativelyeasytoimplement[ChristianCachin,1998].

Hidinginformationinsideimagesisapopulartechniquenowadays[ShashikalaChannalli,2009].AnimagewithasecretmessageinsidecaneasilybespreadovertheWorldWideWeborinnewsgroups.

Themostcommonmethodstomakealterationsintheimagepresentinnoisyareainvolvetheusageoftheleast-significantbitorLSB,masking,filteringandtransformationsonthecoverimage.Thesetechniquescanbeusedwithvaryingdegreesofsuccessondifferenttypesofimagefiles.

3.3.Finding

Moretechniquesaredevelopedforhidingtheinformationtodetecttheuseofsteganography.Whiletheinformationcanbehiddeninsidetextsinawaythatthemessagecanonlybedetectedwiththeknowledgeofthesecretkey.

Awidelyusedtechniqueforimagescanninginvolvesstatisticalanalysis,withthestatisticalanalysisonthelsb,thedifferencebetweenrandomvaluesrealimagevaluecaneasilybedetected.

Thestatistica