外文翻译基于数字水印技术的信息隐藏理论研究.docx

外文翻译基于数字水印技术的信息隐藏理论研究.docx

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外文翻译基于数字水印技术的信息隐藏理论研究

外文资料

InformationHidingThieoreticResearchBasedonDigitalWatermarkTechnology

SchoolofMathematicsandComputerScienceNingxiaUniversitYinchuan,China

Abstract-Withrapidlygrowinginterestinwaystohideinformation,alargenumberofschemeshavebeenproposedforaudioandothermultimediaindigitalpictures,video,audioandothermultimediaobjects.Inanattempttoovercomethisproblem,watermarkinghasbeensuggestedintheliterratureasthemosteffectivemeansforcopyrightprotectionandauthentication.Themainfocusofthisthesisistheproblemofwatermarkingandcompressionofimageduetobandwidthorstorageconstraints.

Keywords:

informationhiding;digitalwatermarking;transparency;robustness

I.Introduction

DuetotherapidlydevelopmentoftheInterestandtheWorld-Wide-Web（WWW）,distributionofdigitalmultimediadatatoalargepopulationofuserscanbedoneveryeasily.Moreover,digitaldatacanbeduplicatedveryfastandwithoutanydegrationinquality-cinsider,forexample,howcommonthecopyingofmusicalCDshasbecomeinthelastfewyears.Naturally,thissituationhasraisedmanyconcernsaboutpossibleviolationsofintellectualpropertyrights.Unauthorizedduplicationanddistributionofcopyrightedmaterial（photographs,music,movies,etc.）,withoutappropriatecompensationtothecopyrightholders,arebecomingincreasinglyproblemtic.Inordertofightpiracy,manycompanies（especiallyintheentertainmentandnewsindustries）havedevotedconsiderableattentiontothedevelopmentofinformationhiding（orwatermarking）techniques.Inplainterms,awatermarkisasignalwhichishideninsidesomemultimediadata,andcarriesinformationaboutthisdata（e.g.,owner,title,dataofcreation,ect）.Thusawatermarkuniquelyidentifiestheworkbeingprotected,andhelpsresolvedisputesabouttheownershipofthedata.

Therehavebeenmanyinstancesofdisputesorlitigationsontheintellectualownershipofmultimediadata.Acopyrightviolationslawsuitthatreceivedextensivepublicityintheearly2000's,wasthatagainstNapster.AndtheDigitalVideoDisk,alsoknownasDigitalVersatileDisk（DVD）consortiumcalledforproposalsforacopyrightmarkingschemetoenforceserialcopymanagement.TheideaisthattheDVDplayerssoldtoconsumerswillallowunlimitedcopyingofhomevideosandtime-shiftedviewingofTVprogrammers,butcannoteasilybeabusedforcommercialpriacy.ElectroniccopyrightmanagementschemeshavealsobeenproposedbyEuropeanprojectssuchasImprimaturandCITED,andAmericanprojectssuchastheproposedbytheWorkingGrouponIntellectualPropertyRights.

Duetoitssignificance,thewatermarkingfieldhasgrowntremendouslyintheinformationhidingtheoretic.Therearenumerousarticles（thereferencestherein）andbooksthatexplainthebasicofwatermarking,exploreitsmanypracticalapplication,andevaluatetheperformanceofvariousschemesunderavarietyofattacks.

II.DigitalWatermarkingSystem

A.Watermarking

Inthecommunicationmodelforwatermarking,thewatermarkembedderplaystheroleofthetransmitter,thewatermarkdetectorplaystheroleofrecieverandtheattackrepresentsthecommunicationchannel（Fig.1）.Theobjectiveistodecodethehiddenmessagereliably;theoriginalimagecanbeconstruedofassideinformationwhichisalwaysavailableattheencoder,butisonlyavailableatthedecoderintheprivatescenario（notthepublicone）.

Inthispaper,atransmittersendsasignalXntoareceive（withntransmissions）,throughthefollowingchannel:

Y"=Xn+Sn+Zn,whereSn,Znareindependent,i.i.d.Gaussianrandomvectors.Here,Snisknowntotheencoder,whileZnactsasnoiseknowntoneitherencoderordecoder.ItisprovedthatthecapacityofthischannelisthesameasifSnwereknowntothedecoderaswell.

Ingeneral,thisnumbergrowslinearlywiththeimagesize,andtheconstantofproportionalityisknownasthecapacityC.PracticalwatermarkingimplementationembedatarateRbits/imagedimension,whereR

B.Characteristicsofwatermarking

Inthedesignofwatermarkingschemes,wemainlythinkabouttwokeyrequirements.

Transparency:

Thehiddenmessageshouldnotinterfereperceptuallywiththehostsignal.Thisrequirementisperfectlyjustifiedbythefactthatwatermarkingaimsatprotectingmultimediadata,whicharesensitive,ingeneral,tochanges.Inotherwords,animageoramusicalpiececouldbecomeuselessiftheintroducedartifacts（duetowatermarking）exceededsomeperceptualthreshold.Thequalityofthewatermarkeddatamustthusbecomparabletothatofthecovertext,arequirementwhichisoftenexpressedintermsofadistoritionconstraint.

Robustness:

Themessagemustbedetectableinthewatermarkedimage（thecovertextisassumedtobeanimagethroughoutthisthesis,thoughsimilartechniquescanbeappliedtoothertypesofmultimediadata）,evenafterdegradationduotomaliciousattacksorotherprocessing（quantization,D/Aconversion,etc）.Ofcourse,detectabilityofthewatermarkiscloselyrelatedtothemaxinumamountofdistortionthatcanbeintroducedbyanattacker.Awatermarkingschemeisrobustifitallowsthehiddenmessagetobeaccuratelydecodedinadistortedimagewhosequalityisclosetothatofthewatermarkedimage（thisrequriementisagainexpressedintermsofadistortionconstraint）.

C.Detectionscenarios

Therearetwodecetionscenarios:

privateandpublic.Intheprivatedecetionscenario,theoriginalimageisavailabletothedecetor,inthepublicscenario,itisnot.Althoughpublicdetectionschemecanbemoreusefulinpractice（sinceitisnotalwayspossibletohavetheoriginalimageavailableduringthedecetion）,privateschemesusuallyoffermorerobustness.

III.WatermarkingRatesInThePresenceOfMemorylessAttacksAndGaussianAttacks

Wechoosethatthememorylessattackisfixed（intermsoftheconditionalprobabilitydistributionoftheattackchannel）,forbothdiscreteandcontinuousalphabets.Weestablisedtheregionachievablerates（Rq,Rw）undermemorylessattacks.

A.DiscreteAlphabets.

ThegeneralformofthewatermarkingsystemunderconsiderationisshowninFig.2.ThewatermarkindexWisuniformlydistributedoverasetofsize2nRw;Ynisthewatermarkedimagewhichcanbefoundinasourcecodebookofsize2nRw,theattackchannelismemoryless.

ThewatermarkdecodeoutputsW'.Weconsideraprivatescenariohere,soweassumethatInisknownatthedecoder.

A.AttackingProcedure

Thewatermarker（whodesignstheencoderpair）triestomaximizetheachievablerateregionwhiletheattackertriestominimizeit[12].Theprocedureofattackareexpressedasfollows:

1.Theencoder（watermarkembedder）isdesignedwithoutanyknowledgeoftheattackconditionaldistributionp.Firstly;thewatermarkdesignsanencodingfunctionf.Thewatermarkmustensurethattheratesarechosensuchthatthewatermarkisdetectedreliablyforanyattackddiatributionpchosenbytheattacker.

2.Theattack,whoknowsk,playssecondandchoosesaconditionaldistributionpfortheattacksuchthatthedistortionconstraintismet.

3.Thewatermarkplaysnext,anddesignshiswatermarkdecodingalgorithmgwithrespecttothedistributionpchosenbytheattacker.

IV.Conclution

Inthispaper,weestablishedtheregionofachievableratesundermemoryattacks.Thepaperisdiscussedthefollowingcase:

1.Thememorylessattackischosenindependentlyoftheembeddingstrategyandisknowntobothencoderanddecoder.Resultsareobtainedfortwostatisticalmodels:

thegeneraldiscretealphabetcaseforarbitraryimagedistributionsanddistortionconstraints,aswellastheGaussiancasewheretheoriginalimageandtheattackchannelarei.i.d.Gaussian,andthedistortionmetricisquadratic.

2.Theinformationandtheattackerplayagamewhichistheattackingprocedure.Specifically,theattackerknowstheencodingfunctionusedbythewatermarker,whilethedecoderknowstheattackdistribution.

Finally,thereareanumberofdirectionforfutureresearch.Allresultsderivedinthisthesisassumeaprivatescenario.Wewerenotabletoastablisedtheregionofachievableratesinapublicscenario,evenforthesimpleGaussiancase.Futhermore,itwouldbeinterestingtoestablishrateregionsforjointwatermarkingandcompressionsystemsunderdistortionconstraintsthatdonotinvolveaveragingofdistortionmeasures.

中文翻译

基于数字水印技术的信息隐藏理论研究

宋丽娟

（宁夏大学数学与计算机科学，银川中国，slj@）

摘要：

随着信息隐藏技术的迅速发展，水印和其它一些在数码照片、视频、音频以及其它的多媒体设备等信息方面相继也提出了很多方案。

为了解决版权保护盒认证的相关问题，有人提出了使用水印作为最有效的手段。

鉴于带宽的限制和压缩存储的问题，本文的重点是研究水印和压缩方面的问题。

关键字：

信息隐藏；数字水印；透明度；鲁棒性

I.引言

由于互联网和计算机的迅速发展，数字多媒体迅速发展到数据同时共享于众多用户是很容易实现的。

此外，数据可以被快速复试而不产生任何质量损耗。

例如，最近几年里，音乐和唱片的拷贝变得非常普遍。

理所当然，这种情形唤起了人们对知识产权侵害的关注。

没有给予版权持有人适当的补偿，而进行未经许可的复制以及传播享有著作权的材料（照片，音乐，电影等），正变得越来越严重。

为了打击盗版，许多公司（尤其是娱乐和新闻行业）相当重视信息隐藏（或数字水印）技术的发展。

简单来说，水印作为一种信号隐藏技术在一些多媒体数据中，并携带有关数据（例如，所有者、标题、制作日期等）的信息。

因此，水印就能唯一的标记受保护的作品，帮助解决有关数据所有权的纷争的问。

有很多的关于多媒体知识产权的纠纷或所有权的诉讼案件方面的例子。

在2000年初一，关于Napster软件版权侵犯的诉讼案得到了普遍关注。

数字视频光盘协会（即数字通用光盘协会）号召提出一些版权保护措施来加强资源的管理。

该想法是，卖给消费者的DVD播放器将允许不受权限的复制家庭录影以及观看的是移电视节目，不能轻易将此行为定位商业侵权。

像Imprimature和CITED的欧洲项目和WorkingGroup提议的关于知识产权的美国项目都提到了电子版权的管理。

由于其重要性，水印领域有了大量关于信息隐藏技术的研究。

有很多文章（其中的参考文献）和书籍都解释了数字水印的基本知识，探索了它的许多实际应用，并评估在各种攻击下的性能。

II.数字水印系统

A.水印

在水印的通信模型中，水印嵌入扮演的是发射机，水印检测器扮演的是接收机。

攻击代表通信系统信道（图1）。

目标是可靠检测出隐藏信息；原始图像可以被理解为一直用于编码器的隐藏信息。

但是，仅仅是在隐藏（不公开）的情况下解码器可用。

在本文中，发射机发出了一个信号Xn到一个接收