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1、14河南科技大学本科毕业设计（论文）AcascadediterativeFouriertransformalgorithmforopticalsecurityapplicationsAbstract:AcascadediterativeFouriertransform(CIFT)algorithmispresentedforopticalsecurityapplications.Twophase-masksaredesignedandlocatedintheinputandtheFourierdomainsofa
2、4-fcorrelatorrespectively,inordertoimplementtheopticalencryptionorauthenticityverification.Comparedwithpreviousmethods,theproposedalgorithmemploysanimprovedsearchingstrategy:modifyingthephase-distributionsofbothmaskssynchronouslyaswellasenlargingthesearchings
3、pace.Computersimulationsshowthatthealgorithmresultsinmuchfasterconvergenceandbetterimagequalityfortherecoveredimage.Eachofthesemasksisassignedtodifferentperson.Therefore,thedecryptedimagecanbeobtainedonlywhenallthesemasksareunderauthorization.Thiskey-assignme
4、ntstrategymayreducetheriskofbeingintruded.Keywords:Opticalsecurity–opticalencryption–cascadediterativeFouriertransformalgorithm1.IntroductionOpticaltechniqueshaveshowngreatpotentialinthefieldofinformationsecurityapplications.RecentlyRéfrégierandJavidiproposed
5、anoveldouble-random-phaseencodingtechnique,whichencodesaprimaryimageintoastationarywhitenoise.ThistechniquewasalsousedtoencryptinformationinthefractionalFourierdomainandtostoreencryptedinformationholographically.Phaseencodingtechniqueswerealsoproposedforoptic
6、alauthenticityverification.WangetalandLietalproposedanothermethodforopticalencryptionandauthenticityverification.Unlikethetechniquesmentionedabove,thismethodencryptsinformationcompletelyintoaphasemask,whichislocatedineithertheinputortheFourierdomainofa4-fcorr
7、elator.Forinstance,giventhepredefinitionsofasignificantimagef(x,y)asthedesiredoutputandaphase-distributionexp{jb(u,v)}intheFourierdomain,it’seasytooptimizetheotherphasefunctionexp{jp(x,y)}withamodifiedprojectionontoconstraintsets(POCS)algorithm[10].Thereforet
8、heimagef(x,y)isencodedsuccessfullyintoexp{jp(x,y)}withtheaidofexp{jb(u,v)}.Inotherwords,thefixedphaseexp{jb(u,v)}servesasthelockwhiletheretrievedphaseexp{jp(x,y)}servesasthekeyofthesecuri
