《科技英語文獻閱讀與翻譯》Unit-1-TextB

UnitOne

TextBDigitalSignatureinAppliedCryptography3/20/20251第1頁BackgroundInformation3/20/20252UnitOne第2頁cryptography

Cryptographyisthestudyofmathematicaltechniquesrelatedtoaspectsofinformationsecuritysuchasconfidentiality,dataintegrity,entityauthentication,anddataoriginauthentication.AstheInternetandotherformsofelectroniccommunicationbecomemoreprevalent,electronicsecurityisalsobecomingincreasinglyimportant.Cryptographyisusedtoprotecte-mailmessages,creditcardinformation,andcorporatedata.3/20/20253UnitOne第3頁publickeyItisthekeyforusewithpublickeyencryptionmethodsthatispubliclymadeavailable.Itispublishedbythekeyholderortheissuingcertificationauthority.Thecertificationauthority’sdirectoryservercandistributeitbydisk,webdownloadore-mail.Thepublickeycanbecertifiedusinganelectroniccertificateissuedandsignedbyacertificationauthority.

3/20/20254UnitOne第4頁privatekey

Itisthekeyforusewithasymmetricencryptionthatisaccessibletothekeyholderonly.Asymmetricencryptionusesdifferentkeysforencryptionanddecryption.Eachparticipantisassignedapairofkeys,consistingofanencryptionkeyandacorrespondingdecryptionkey.Aprivatekeyisusedforgeneratingdigitalsignaturesandfordecryptingdata.3/20/20255UnitOne第5頁

hashfunctionandhashvalue

HashFunctionisanalgorithmthattransformsastringofcharactersintoausuallyshortervalueofafixedlengthorakeythatrepresentstheoriginalvalue.Thisiscalledthehashvalue.Hashfunctionsareemployedinsymmetricandasymmetricencryptionsystemsandareusedtocalculateafingerprint/imprintofamessageordocument.3/20/20256UnitOne第6頁hashfunctionandhashvalueWhenhashingamessage,themessageisconvertedintoashortbitstring--ahashvalue--anditisimpossibletore-establishtheoriginalmessagefromthehashvalue.Ahashvalueisuniqueinthesensethattwomessagescannotresultinthesamebitstring,andanyattempttomakechangestothemessagewillnegatethevalueandthusthesignature.

3/20/20257UnitOne第7頁

digitalcash

Digitalcashisadigitallysignedpaymentmessagethatservesasamediumofexchange.Digitalcashisasystemofpurchasingcashcreditsinrelativelysmallamounts,storingthecreditsinyourcomputer,andthenspendingthemwhenmakingelectronicpurchasesovertheInternet.Theoretically,digitalcashcouldbespentinverysmallincrements,suchastenthsofacent(U.S.)orless.Mostmerchantsacceptdigitalcashsofar,however,theyalsouseitasanalternativetootherformsofpaymentforsomewhathigherpricepurchases.3/20/20258UnitOne第8頁sourcecode

Sourcecodeisanyseriesofstatementswritteninsomehuman-readablecomputerprogramminglanguage.Inmodernprogramminglanguages,thesourcecodewhichconstitutesaprogramisusuallyinseveraltextfiles,butthesamesourcecodemaybeprintedinabookorrecordedontape(usuallywithoutafilesystem).Thetermistypicallyusedinthecontextofaparticularpieceofcomputersoftware.3/20/20259UnitOne第9頁LanguagePoints3/20/202510UnitOne第10頁Thismeansthataneavesdropper,referstoEve,willnotbeabletolisteninontheircommunication.(para.1):

eavesdroppern.apersonwholistenssecretlytoprivateconversationNowadaysmanyeavesdroppersareabletoconnecttoyourpersonalcomputerandphonenetworks.eavesdropv.listensecretlytoprivateconversationofothersAnewlawhasbeenapprovedbythecongresstoallowtoeavesdroponprivatephoneconversations.3/20/202511UnitOne第11頁Digitalsignaturesarecoupledtotheelectronicdocumenttowhichtheyapply.(para.2):v.1)tolinkorassociatetogether,connecteg:Pressure,coupledwithnervousnessmadeithardforthepresidentcandidatetofallasleep.2)tojoinasspouses,marryeg:Fallinginloveatthefirstsight,theycoupledasaperfectmatch.3/20/202512UnitOne第12頁Inpublickeycryptography,anythingAliceencryptswithBob’spublickeycanbedecryptedbyBobwiththecorrespondingprivatekey.(para.3):

Inpublickeycryptography,anythingAliceencodeswithBob’spublickeycanbedecodedbyBobwiththematchingprivatekey.譯文:在公鑰密碼系統(tǒng)里,艾麗斯用鮑勃公鑰加密任何內容都能夠被鮑勃用對應私鑰解密.3/20/202513UnitOne第13頁Encryptingwithaprivatekeythuscanberegardedasanequivalenttoplacingone’ssignatureonthemessage.(para.4):

equivalentadj.(to)beequalinvalue,amount,meaning

n.somethingthatisequalinvalue,amount,meaningeg:IsthereaFrenchwordthatistheexactequivalentoftheEnglishwordchurch?3/20/202514UnitOne第14頁Acryptographichashfunctioncantransforminputofanarbitrarylength…(para.7):transformv.changecompletelyinform,appearance,ornatureeg:Fatherhoodtransformedhimintoamoreresponsibleman.Asteamenginetransformsheatintopower.transformationn.eg:Localpeoplehavemixedfeelingsabouttheplannedtransformation

oftheirtownintoaregionalcapital.3/20/202515UnitOne第15頁Afterall,thesecondpropertyofthehashfunctionsaysthatthechancethat…(para.11):chancen.possibility;likelihoodeg:Whatareherchancesofsurvival?Hisquittinghasimprovedmychancesofpromotion.(The)chancesare(that)…:Itislikelythat…eg:Chancesarethey’llbeintentonleavingforEurope.3/20/202516UnitOne第16頁Usingthispublickeythebrowsercandeterminethat

thecertificateisauthentic.(para.18):authenticadj.genuine,oflegitimateorundisputedorigin;trustworthyeg:ThespecialistconfirmedthatthisisanauthenticpieceofpaintingbyPicasso.3/20/202517UnitOne第17頁Themanufacturerofcoursepromisesthattheapplicationwillnotdoanythingmalicious.(para.24):

Theproducercertainlypr