混合混沌序列与混沌图像加密技术研究

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1、西南交通大学硕士学位论文混合混沌序列与混沌图像加密技术研究姓名：许克兵申请学位级别：硕士专业：密码学指导教师：黄文培20070501西南交通大学硕士研究生学位论文第1I页AbstractWithdevelopmentofinformationtechnologyandincreasingfrequencyofinformationexchange，theresearchoninformationsecnrityengineeringisbecomingmoreandmoreimportant．Asanoveltechnologyin

2、cryptography,digitalchaoticcipherhasbeenattractedresearcherdenseinterestandwidelystudied．Chaos，asakindofnonlinearphenomenon，hasmanyremarkablecharacteristics：suchaspseudo—random，unpredictabilityofevolutionofitsorbits，propertiesofmixingandsensitivitytoinitialconditionsan

3、dsystemparameters．Thesecharacteristicsareinaccordancewiththerequirementsofcryptography．Researchshowsthattherearesomerelationsbetweentraditionalcipherandchaos．Challengeshavebeensetwithtraditionalcryptographybecauseofthebull【datacapacityandhighredundancyofwidely·usedpatt

4、ernsandmulti-mediainformation，whilechaoticcipherhasgreatsuperiorityovertheencryptionofmulti·mediainformation．Thisthesisintroducesthedevelopment，rudimentaryandrelevantknowledgeofchaostheory．Thep托limiⅡaIiesincludingthetheoryofmodemcryptographyandchaosdynamicsarepresented

5、atfirst．Thentheauthorhasdiscussedthechaoticsequencesgeneratedvialogisticmapwithchaosandhasclaimedthatthistypechaoticsequencesarenotsuitableforkeystream．Basedonthediscussionabove，aclassofmixedchaoticsequences，whichareproducedbycombininglogisticchaoticsequencesandm—seque

6、ncesinformofexclusive·0凡hasbeenproposedinthispaper．Thecryptographicproperties，suchaslongperiod，randomicity,balance，muninglength,correlationfunctionandlinearcomplexity,ofmixedchaoticsequenceshavebeenanalyzedindetail．TheresultsshowthatthenewapproachallowsUStoimprovetheco

7、mplexityandtheperiodofthechaoticsystemunderthefinite—precisioncircumstances．Withthesuperiorityofchaoticcipheroverimagingencryption，thisthesisemphasizesontheresearchonchaoticimagingencryptiontechnologyandthemeth6dofimagingpermutationmatrix，producedbyonedimbnsionalchaoti

8、cmap，twodimensionalchaoticmapsrespectively．Thismethodiscapableofchangingoriginalimagesintounrecognizablechaoticimages