《科技英语文献阅读与翻译》UnitTextBPPT课件

UnitOneTextB,DigitalSignatureinAppliedCryptography,06.05.2020,.,2,BackgroundInformation,06.05.2020,.,3,cryptography,Cryptographyisthestudyofmathematicaltechniquesrelatedtoaspectsofinformationsecuritysuchasconfidentiality,dataintegrity,entityauthentication,anddataoriginauthentication.AstheInternetandotherformsofelectroniccommunicationbecomemoreprevalent,electronicsecurityisalsobecomingincreasinglyimportant.Cryptographyisusedtoprotecte-mailmessages,creditcardinformation,andcorporatedata.,06.05.2020,.,4,publickey,Itisthekeyforusewithpublickeyencryptionmethodsthatispubliclymadeavailable.Itispublishedbythekeyholderortheissuingcertificationauthority.Thecertificationauthoritysdirectoryservercandistributeitbydisk,webdownloadore-mail.Thepublickeycanbecertifiedusinganelectroniccertificateissuedandsignedbyacertificationauthority.,06.05.2020,.,5,privatekey,Itisthekeyforusewithasymmetricencryptionthatisaccessibletothekeyholderonly.Asymmetricencryptionusesdifferentkeysforencryptionanddecryption.Eachparticipantisassignedapairofkeys,consistingofanencryptionkeyandacorrespondingdecryptionkey.Aprivatekeyisusedforgeneratingdigitalsignaturesandfordecryptingdata.,06.05.2020,.,6,hashfunctionandhashvalue,HashFunctionisanalgorithmthattransformsastringofcharactersintoausuallyshortervalueofafixedlengthorakeythatrepresentstheoriginalvalue.Thisiscalledthehashvalue.Hashfunctionsareemployedinsymmetricandasymmetricencryptionsystemsandareusedtocalculateafingerprint/imprintofamessageordocument.,06.05.2020,.,7,hashfunctionandhashvalue,Whenhashingamessage,themessageisconvertedintoashortbitstring-ahashvalue-anditisimpossibletore-establishtheoriginalmessagefromthehashvalue.Ahashvalueisuniqueinthesensethattwomessagescannotresultinthesamebitstring,andanyattempttomakechangestothemessagewillnegatethevalueandthusthesignature.,06.05.2020,.,8,digitalcash,Digitalcashisadigitallysignedpaymentmessagethatservesasamediumofexchange.Digitalcashisasystemofpurchasingcashcreditsinrelativelysmallamounts,storingthecreditsinyourcomputer,andthenspendingthemwhenmakingelectronicpurchasesovertheInternet.Theoretically,digitalcashcouldbespentinverysmallincrements,suchastenthsofacent(U.S.)orless.Mostmerchantsacceptdigitalcashsofar,however,theyalsouseitasanalternativetootherformsofpaymentforsomewhathigherpricepurchases.,06.05.2020,.,9,sourcecode,Sourcecodeisanyseriesofstatementswritteninsomehuman-readablecomputerprogramminglanguage.Inmodernprogramminglanguages,thesourcecodewhichconstitutesaprogramisusuallyinseveraltextfiles,butthesamesourcecodemaybeprintedinabookorrecordedontape(usuallywithoutafilesystem).Thetermistypicallyusedinthecontextofaparticularpieceofcomputersoftware.,06.05.2020,.,10,LanguagePoints,06.05.2020,.,11,Thismeansthataneavesdropper,referstoEve,willnotbeabletolisteninontheircommunication.(para.1):,eavesdroppern.apersonwholistenssecretlytoprivateconversationNowadaysmanyeavesdroppersareabletoconnecttoyourpersonalcomputerandphonenetworks.eavesdropv.listensecretlytoprivateconversationofothersAnewlawhasbeenapprovedbythecongresstoallowtoeavesdroponprivatephoneconversations.,06.05.2020,.,12,Digitalsignaturesarecoupledtotheelectronicdocumenttowhichtheyapply.(para.2):,v.1)tolinkorassociatetogether,connecteg:Pressure,coupledwithnervousnessmadeithardforthepresidentcandidatetofallasleep.2)tojoinasspouses,marryeg:Fallinginloveatthefirstsight,theycoupledasaperfectmatch.,06.05.2020,.,13,Inpublickeycryptography,anythingAliceencryptswithBobspublickeycanbedecryptedbyBobwiththecorrespondingprivatekey.(para.3):,Inpublickeycryptography,anythingAliceencodeswithBobspublickeycanbedecodedbyBobwiththematchingprivatekey.译文:在公钥密码系统里,艾丽斯用鲍勃的公钥加密的任何内容都可以被鲍勃用对应的私钥解密.,06.05.2020,.,14,Encryptingwithaprivatekeythuscanberegardedasanequivalenttoplacingonessignatureonthemessage.(para.4):,equivalentadj.(to)beequalinvalue,amount,meaningn.somethingthatisequalinvalue,amount,meaningeg:IsthereaFrenchwordthatistheexactequivalentoftheEnglishwordchurch?,06.05.2020,.,15,Acryptographichashfunctioncantransforminputofanarbitrarylength(para.7):,transformv.changecompletelyinform,appearance,ornatureeg:Fatherhoodtransformedhimintoamoreresponsibleman.Asteamenginetransformsheatintopower.transformationn.eg:Localpeoplehavemixedfeelingsabouttheplannedtransformationoftheirtownintoaregionalcapital.,06.05.2020,.,16,Afterall,thesecondpropertyofthehashfunctionsaysthatthechancethat(para.11):,chancen.possibility;likelihoodeg:Whatareherchancesofsurvival?Hisquittinghasimprovedmychancesofpromotion.(The)chancesare(that):Itislikelythateg:ChancesaretheyllbeintentonleavingforEurope.,06.05.2020,.,17,Usingthispublickeythebrowsercandeterminethatthecertificateisauthentic.(para.18):,authenticadj.genuine,oflegitimateorundisputedorigin;trustworthyeg:ThespecialistconfirmedthatthisisanauthenticpieceofpaintingbyPicasso.,06.05.2020,.,18,Themanufacturerofcoursepromisesthattheapplicationwillnotdoanythingmalicious.(para.24):,Theproducercertainlypromisesthattheapplicationwillnotdoanythingmeanorharmful.译文:软件生产商当然会承诺使用他们的软件不会对用户产生任何不良后果.maliciousadj.ill-willed,desiringtoharmotherseg:Dontbelievethemaliciousgossip.malicen.eg:Therefugeesbearmalicetowardsnone.,06.05.2020,.,19,TheCPUinaPCwouldcheckthedigitalsigna