《計(jì)算機(jī)專(zhuān)業(yè)英語(yǔ)》課件第24章

UnderstandingEncryption

Securityexpertsagreethatcircumspectuseofstrongencryptionisthebestwaytokeepconfidentialdatasecretfrominterloperswhomaystealcomputers,intercepte-mail,orslipthroughcracksinfirewalls.Encryptionisthereal-worldworkhorseofthescienceofcryptography.Itistheprocessofconvertingdataintoaformthatisunintelligiblewithoutthesecretdecryptionkey.

First,let’sgetafewtermsoutoftheway.1Incryptography,afileofanytypethatisn’tencryptediscalledplaintext;encrypteddataiscalledciphertext.Anencryptionalgorithmorcipher,suchasaweakonecalledCaesarCipher,mightreplaceeachcharacterofplaintextbyskippingtwoletterssothatAbecomesD,PbecomesS,ZbecomesC,andsoonthroughoutthealphabet.Thus,plaintextisnowgarbledciphertext.

Ofcourse,thesecurityrenderedbysuchanantiquatedalgorithmisnil.2Modernencryptionalgorithmsarenecessarilymoresophisticatedbecausetheciphertextmayoftenbeprotectinginformationworththousandsormillionsofdollars.3Today’sstrongalgorithms,whichneednotremainsecret,poseamathematicalproblemthatishardtosolvewithoutthecorrectkey.Tocryptographers,“hard”meanscomputingwiththousandsofsystemsandgettingananswerinmonths,years,orsometimesaftertheendoftheuniverse.

Encryptionalgorithmcangenerallybedividedintotwotypes:conventionalalgorithmsandpublic-keyalgorithms.(Thereareothersthathavespecializedfunctions,forinstance,digitalsignatureandkeyagreementalgorithms.)Conventionalalgorithmsaresymmetricalandrelyonthesamekeyforencryptionanddecryption.Theyarebestusedtoencryptfilesonaharddisk.

4Public-keyalgorithms,ontheotherhand,areasymmetrical,usingdifferentkeys,apublickey,andasecretkey,forencryptionanddecryption.Public-keyalgorithmsletyousharefiles,particularlye-mailcorrespondence,withotherusers.Inapublic-keysystem,forinstance,ifZooeywantstosendFrannyanencryptionmessage,FannywouldfirstsendZooeyherpublicKey.ZooeythenusesFranny’spublic-keytoencryptamessagetoher.WhenFrannyreceivesthemessagefromZooey,shecandecryptthemessagewithhersecretkey.

Public-keyencryptionsolvestheproblemofmanagingseveralkeys,butencryptionisslowcomparedtoconventionalencryption.Keymanagementinconventionalencryption,however,isaproblembecauseseveralfilesmaybeencryptedwithdifferentkeys.

Althoughgoodconventionalandpublic-keyalgorithmsarebothconsideredstrong,theirrespectivekeylengthsforsecurityvary.Awhileago,anadhocgroupofcomputerscientistsandcryptographerscontributedtoapaperthatrecommendedakeyofatleast90bitsforsymmetricalgorithmsusedincommercialsecurity.Manydomesticproductsalreadyexceedthatrecommendationandallow128bitkeys,Akeysizeof128bitsmeansthatthereare2128possiblekeys,enoughtofoilabruteforceattack(tryingeverypossiblekey).5Symmetricalgorithmswhosekeysizeis40bitscanbeandhavebeencrackedbyhackers.

Publickeys,however,mustbelarger,becausethemathematicsinanasymmetricalgorithmaredifferent.KeysizesforgoodsecurityusingtheRSApublic-keyalgorithmrangefrom768bitsto2,048bits.6CrackingRSAmeansconfrontingwhatmathematiciansbelievetobethehardproblemoffactoringlargenumbers.NewWordsencryptionn.加密securityn.安全expertn.專(zhuān)家circumspectadj.周到的,周密的confidentialadj.保密的,機(jī)密的interceptv.竊聽(tīng)crackv.破譯firewalln.防火墻workhorsen.骨干cryptographyn.密碼unintelligibleadj.難解的decryptionn.解碼encryptv.將……譯成密碼plaintextn.明文(未加密的電文),明碼文本ciphertextn.加密文本algorithmn.算法cipherv.加密skipv.跳過(guò)garblev.混淆renderv.交付antiquatev.廢棄necessarilyadv.必要地posev.提出cryptographern.破解密碼者digitaladj.數(shù)字的symmetricaladj.對(duì)稱(chēng)的asymmetricaladj.不對(duì)稱(chēng)的correspondencen.一致性,通信decryptv.解密respectiveadj.分別的varyv.使多樣化contributev.貢獻(xiàn)recommendv.推薦exceedv.超過(guò)recommendationn.推薦confrontv.面臨PhrasesandExpressions

sothat以便divideinto把……分開(kāi)forinstance例如ontheotherhand另一方面compareto與……比較TheExplanationofDifficultStatements

1.Incryptograghy,afileofanytypethatisn’tencryptediscalledplaintext.

分析:“thatisn’tencrypted”作定語(yǔ),此處“that”為關(guān)系代詞,故不可以省略。

句意:在密碼學(xué)中,沒(méi)有加密的任何形式的文件都叫做普通文本(也可譯為“明文”)。

2.Modernencryptionalgorithmsarenecessarilymoresophisticatedbecausetheciphertextmayoftenbeprotectinginformationworththousandsormillionsofdollars.

分析:“worththousandsormillionsofdollars”為形容詞短語(yǔ)作定語(yǔ),句型“beworthdoingsth./sb.”意為“值得做某事”。句意:現(xiàn)代加密算法必須更為復(fù)雜,因?yàn)槊艽a文本常為用戶(hù)保護(hù)價(jià)值數(shù)十萬(wàn)或數(shù)百萬(wàn)美元的信息。

3.Today’sstrongalgorithms,whichneednotremainsecret,poseamathematicalproblemthatishardtosolvewithoutthecorrectkey.

分析:“whichneednotremainsecret”和“thatishardtosolvewithoutthecorrectkey”同為定語(yǔ)從句,翻譯時(shí)可采用“分譯法”。句意:今天,強(qiáng)有力的算法無(wú)須保密,因?yàn)樗岢龅臄?shù)學(xué)問(wèn)題在沒(méi)有正確的密鑰情況下是難以解開(kāi)的。

4.Public-keyalgorithms,ontheotherhand,areasymmetrical,usingdifferentkeys,publickey,andasecretkey,forencryptionanddecryption.

分析:“usingdifferentkeys,publickey,andasecretkey,forencryptionanddecryption”為現(xiàn)在分詞作伴隨情況的狀語(yǔ)。句意:公開(kāi)密鑰算法法則是不對(duì)稱(chēng)的,采用不同的密鑰,一個(gè)公開(kāi)的密鑰和一個(gè)秘密的密鑰,用來(lái)加密和解密。

5.Symmetricalgorithmswhosekeysizeis40bitscanbeandhavebeencrackedbyhackers.

分析:“whosekeysizeis40bits”為定語(yǔ)從句,whose在從句中作定語(yǔ)。

句意:密鑰長(zhǎng)度為40位的對(duì)稱(chēng)算法可能并且已經(jīng)被黑客破譯了。

6.CrackingRSAmeansconfrontingwhatmathematiciansbelievetobethehardproblemoffactoringlargenumbers.

分析:“meandoingsth.”的意思是“意味著”、“有……的意思”,“meantodosth.”的意思是“打算做某事”

句意:破譯RSA意味著面臨數(shù)學(xué)家們所認(rèn)為的問(wèn)題——分解大量數(shù)字因子的難題。GrammarTranslationSkills被動(dòng)語(yǔ)態(tài)的翻譯方法

英語(yǔ)中被動(dòng)語(yǔ)態(tài)使用廣泛,尤其是科技作品使用更多,而漢語(yǔ)使用面較窄,因此在翻譯科技作品時(shí),英語(yǔ)被動(dòng)語(yǔ)態(tài)一般翻譯成主動(dòng)語(yǔ)態(tài)。具體有如下翻譯方法。

1.把被動(dòng)句譯成主動(dòng)句

當(dāng)英語(yǔ)被動(dòng)句的主語(yǔ)是無(wú)生命名詞時(shí),常常直譯成漢語(yǔ)的主動(dòng)形式。例如:

Thequalityofthenewproductshasbeengreatlyimproved.這種新產(chǎn)品的質(zhì)量有了很大的提高。

Thisformulahasalreadybeenmentionedabove.這個(gè)公式上面已經(jīng)提到過(guò)。

2.用“將”、“把”、“使”等詞譯成無(wú)主語(yǔ)主動(dòng)句例如:

ThisisdonebyassignaportnumbertoeveryTCPconnection.這是通過(guò)為每個(gè)TCP連接分配一個(gè)端口號(hào)實(shí)現(xiàn)的。

Temperatureischangedquicklyfromroomtemperatureto125℃andisheldthereforatleast15minutes.使溫度很快從室溫升高到125度,并至少保持15分鐘。

3.特別突出被動(dòng)者的譯法要特別突出被動(dòng)者時(shí),把英語(yǔ)的被動(dòng)句譯成漢語(yǔ)的主動(dòng)句,常用“經(jīng)過(guò)”、“由”、“被”、“受”、“讓”、“給”、“靠著”、“遭”、“加以”、“為……所”、“是……的”等詞表示。例如:

Waterisusuallyconsideredasbeingacompoundoftwoelements.水通常被認(rèn)為是由兩種元素構(gòu)成的化合物。

Thequestionwillbeansweredfirst.這個(gè)問(wèn)題總是被首先予以回答。

4.加主動(dòng)者的譯法根據(jù)句意加上“人們”、“我們”、“大家”、“有人”等詞譯成主動(dòng)句。例如:

Hewasseenbuyinganewwashingmachineinthesupermarket.有人看見(jiàn)他在超級(jí)市場(chǎng)買(mǎi)了一臺(tái)新洗衣機(jī)。

Thematterwasveryoftentalkedabout.我們?cè)啻握劦竭@件事。

5.把英語(yǔ)的被動(dòng)句譯成漢語(yǔ)因果句例如:

Thethroatisaffectedbyacold.喉嚨因患風(fēng)寒而痛。

Thecropswerebadlydamagedbyaflood.農(nóng)作物因水災(zāi)而毀壞。

6.主語(yǔ)變賓語(yǔ)的翻譯將原文中的主語(yǔ)在譯文中變?yōu)橘e語(yǔ),譯為漢語(yǔ)主動(dòng)語(yǔ)態(tài)。例如:

Thistaskmustbefulfilledbyusintime.我們必須及時(shí)完成這個(gè)任務(wù)。

7.常見(jiàn)句型的翻譯有些常用句型的翻譯方法需要注意，例如：

Itissaidthat據(jù)說(shuō)

Itisknownthat眾所周知

Itisbelievedthat大家相信

Itisgenerallyagreedthat人們通常認(rèn)為

Itisconsideredthat據(jù)估計(jì),人們認(rèn)為

Itisclaimedthat據(jù)稱(chēng),有人宣稱(chēng)

Itisassumedthat假設(shè),假定

Ithasbeenprovedthat已經(jīng)證明

Itmustbeadmittedthat老實(shí)說(shuō),必須承認(rèn)例如:

Ithasbeenprovedthatenergycannotbedestroyed;itcanonlybechangedintootherforms.已經(jīng)證明,能量是不可能消滅的,只能轉(zhuǎn)換成其它形式。Itisgenerallyrecognizedthatlighthasavastcapacityfortransmittinginformation.一般認(rèn)為,光傳播信息的容量極大。ExercisesⅠ.Fillintheblanksaccordingtothetext:(1)Securityexpertsagreethatcircumspectuseof___________isthebestwaytokeepconfidentialdatasecretfrominterlopers.(2)Incryptography,afileofanytypethatisn’tencryptediscalle______________;encrypteddataiscalled______________.(3)Today’sstrongalgorithms,whichneednotremainsecret,posea__________thatishardtosolvewithoutthecorrectkey.(4)Encryptionalgorithmcangenerallybedividedintotwotypes:______________andpubic-keyalgorithms.(5)______________algorithmsletyousharefiles,particularlye-mailcorrespondence,withotherusers.Ⅱ.Decidewhethereachofthefollowingstatementsistrueorfalseaccordingtothetext:(1)Encryptionistheprocessofconvertingdataintoaformthatisunintelligiblewithoutthesecretdecryptionkey.(2)Modernencryptionalgorithmsarenecessarilymoresophisticatedbecausetheciphertextmayoftenbeprotectinginformationworththousandsormillionsofdollars.(3)Conventionalalgorithmsaresymmetricalandrelyonthedifferentkeyforencryptionanddecryption.(4)Public-keyencryptionsolvestheproblemofmanagingseveralkeys,butencryptionisfastcomparedtoconventionalencryption.(5)Akeysizeof128bitsmeansthatthereare2128possiblekeys,enoughtofoilabrute-forceattack(tryingeverypossiblekey).Ⅲ.TranslatethefollowingsentencesintoChinese:(1)Candidatesarerequiredtopresentthemselves15minutesbeforetheexamination.(2)Attentionshouldbepaidthestudyofminoritynationalities’culture.(3)Itisconsideredofnouselearningatheorywithoutpractice.(4)Althoughgoodconventionalandpublic-keyalgorithmsarebothconsideredstrong,theirrespectivekeylengthsforsecurityvary.(5)WebswitchingisdesignedtoaddresstherequirementsofWebtraffic.Ⅳ.TranslatethefollowingparagraphintoChinese:

Thenumberofbusinesscrimesofalltypesisprobablydecreasingasadirectresultofincreasingautomation.Whenabusinessactivityiscarriedoutwithcomputerandcommunicationssystems,dataarebetterprotectedagainstmodification,destruction,disclosure,misappropriation,misrepresentation,andcontamination.Computersimposeadisciplineoninformationworkersandfacilitateuseofalmostperfectautomatedcontrolsthatwereneverpossiblewhenthesehadtobeappliedbytheworkersthemselvesundermanagementedict.Forexample,acontrolinacomputertodetectalltransactionaboveacertainamountandflagthemforlaterauditworksperfectlyeverytime.Computerhardwareandsoftwaremanufacturesarealsodesigningcomputersystemsandprogramsthataremoreresistanttotampering.ReadingMaterialsComputerCrime(VarietyandExtent)

Computerhavebeenusedformostkindsofcrime,includingfraud,theft,embezzlement,burglary,sabotage,espionage,murder,andforgery,sincethefirstcaseswerereportedin1958.Onestudyof1,500computercrimesestablishedthatmostofthemwerecommittedbytrustedcomputeruserswithinbusinesses—personswiththerequisiteskills,knowledge,access,andresources.Muchofknowncomputercrimehasconsistedofenteringfalsedataintocomputers,whichissimplerandsaferthanthecomplexprocessofwritingaprogramtochangedataalreadyinthecomputer.Withtheadventofpersonalcomputertomanipulateinformationandaccesscomputersbytelephone,increasingnumbersofcrimes—mostlysimplebutcostlyelectronictrespassing,copyrighted-informationpiracy,andvandalism—havebeenperpetratedbycomputerhobbyists,knownas“hackers,”whodisplayahighleveloftechnicalexpertise.Organizedprofessionalcriminalhavebeenattackingandusingcomputersystemsadstheyfindtheiroldactivitiesandenvironmentsbeingautomated.

Therearenovalidstatisticsabouttheextentofcomputercrime.Victimsoftenresistreportingsuspectedcases,becausetheycanlosemorefromembarrassment,lostreputation,litigation,andotherconsequentiallossesthanfromtheactsthemselves.Limitedevidenceindicatesthatthenumberofcomputersinbusinessapplicationswherecrimehastraditionallyoccurred.Thelargestrecordcrimesinvolvinginsurance,banking,productinventories,andsecuritieshaveresultedinlossesoftensofmillionstobillionsofdollars—allfacilitatedbycomputers.NewWordsandExpressions

fraudn.欺騙,欺詐行為embezzlementn.貪污,盜用theftn.偷竊burglaryn.夜盜行為,盜竊sabotagen.(對(duì)財(cái)產(chǎn)等)故意破壞,破壞活動(dòng)espionagen.諜報(bào),間諜活動(dòng)forgeryn.(簽字,文件等)偽造,贗品requisitea.必要的,必不可少的adventn.出現(xiàn),到來(lái)trespassvi.非法入侵piracyn.侵犯版權(quán),海盜行為vandalismn.破壞文化行為,破壞(他人或公共)財(cái)產(chǎn)hobbyistn.有業(yè)余癖好的人Questions(1)WhichkindsofcrimehaveComputerbeenusedfor?(2)Wherehascrimetraditionallyoccurred?ComputerCrime(RemediesandLawEnforcement)

Thenumberofbusinesscrimesofalltypesisprobablydecreasingasadirectresultofincreasingautomation.Whenabusinessactivit