Управление на ключове

Mainperformance

Keymanagementincludesallaspectsfromkeygenerationtokeydestruction.Mainlymanifestedinthemanagementsystem,managementagreementandkeygeneration,distribution,replacementandinjection,etc.Formilitarycomputernetworksystems,duetousermobility,affiliationandcoordinatedcombatcommandarecomplicated,higherrequirementsareputforwardforkeymanagement.

Процес

Генериране на ключ

Дължината на ключа трябва да е достатъчно дълга. Най-общо казано, колкото по-голяма е дължината на ключа, толкова по-голямо е съответното ключово пространство и по-трудно е за нападателя да използва изчерпателно отгатване на паролата.

Chooseagoodkeyandavoidweakkeys.Therandombitstringgeneratedbytheautomaticprocessingdeviceisagoodkey.Whenchoosingakey,youshouldavoidchoosingaweakkey.

Forpublickeycryptosystems,keygenerationismoredifficultbecausethekeymustsatisfycertainmathematicalcharacteristics.

Keygenerationcanbeachievedthroughonlineorofflineinteractivenegotiation,suchascryptographicprotocols.

Keydistribution

Theuseofsymmetricencryptionalgorithmsforconfidentialcommunicationrequiresthesharingofthesamekey.Usually,amemberofthesystemselectsasecretkeyfirst,andthentransmitsittoanothermemberorothermembers.TheX9.17standarddescribestwotypesofkeys:keyencryptionkeysanddatakeys.Thekeyencryptionkeyencryptsotherkeysthatneedtobedistributed;whilethedatakeyonlyencryptstheinformationflow.Thekeyencryptionkeyisgenerallydistributedmanually.Toenhanceconfidentiality,thekeycanalsobedividedintomanydifferentpartsandthensentoutondifferentchannels.

Ключ за потвърждение

Ключът се предава с някои прикачени битове за откриване и коригиране на грешки. Когато ключът има грешка при предаване, той може лесно да бъде извлечен и ако е необходимо, ключът може да бъде предаден.

Thereceivingendcanalsoverifywhetherthereceivedkeyiscorrect.Thesenderencryptsaconstantwiththekey,andthensendsthefirst2-4bytesoftheciphertexttogetherwiththekey.Atthereceivingend,dothesamework.Ifthedecryptedconstantatthereceivingendcanmatchtheconstantatthesendingend,thetransmissioniserror-free.

Updatingthekey

Whenthekeyneedstobechangedfrequently,itisindeeddifficulttodistributethenewkeyfrequently.Aneasiersolutionistochangethekeyfromtheoldone.Anewkeyisgeneratedfromthekey,sometimescalledakeyupdate.Youcanuseaone-wayfunctiontoupdatethekey.Ifbothpartiessharethesamekeyandoperatewiththesameone-wayfunction,thesameresultwillbeobtained.

Съхранение на ключове

Ключовете могат да бъдат съхранени в мозъка, карта с магнитни ленти, смарткарта. Ключът може също така да бъде разделен на две части, като едната половина се съхранява в терминала, а другата се съхранява в ключа ROM. Също така е възможно да се използват методи, подобни на ключа за криптиране на ключа, за криптиране и запазване на трудния за запомняне ключ.

Резервен ключ

Ключ, секретно разделение, споделяне на секрети и т.н. могат да се използват за архивиране на ключ.

Theeasiestwayistouseakeyescrowcenter.Keyescrowrequiresalluserstohandovertheirkeystothekeyescrowcenter,andthekeyescrowcenterbacksupandkeepsthekeys(suchaslockedinasafesomewhereorencryptedandstoredwiththemasterkey),Oncetheuser'skeyislost(suchastheuserforgetsthekeyortheuseraccidentallydies),inaccordancewithcertainrulesandregulations,theuser'skeycanbeobtainedfromthekeyescrowcenter.Anotherbackupsolutionistousesmartcardsastemporarykeyescrow.Forexample,Alicestoresthekeyinthesmartcard,andgivesittoBobwhenAliceisaway.BobcanusethecardtodoAlice'swork.WhenAlicereturns,Bobreturnsthecard.Becausethekeyisstoredinthecard,BobIdon'tknowwhatthekeyis.

Secretdivisiondividesthesecretintomanypieces.Eachpiecedoesnotmeananything,butwhenthesepiecesareputtogether,thesecretwillbereproduced.

По-добре да използвате протокол за споделяне на тайни. Разделете ключовете Kinton на блокове и всяка страна се нарича негова "сянка". Знаейки още повече блокове, можете да изчислите ключа K, като знаете, че всеки 1 или по-малко блокове не могат да бъдат изчислени Ключът K, който се нарича (m, n) прагова (базирана на праг) схема. ,проективнагеометрия,линейнаалгебра,SunTzutheorem и др.

Схемата на интерполационния полином на Лагранж е лесна за разбиране прагова схема за споделяне на тайна (m,n).

Secretsharingsolvestwoproblems:first,ifthekeyisaccidentallyorintentionallyexposed,theentiresystemisvulnerabletoattack;second,ifthekeyislostordamaged,allinformationinthesystemcannotbeused.

Keyvalidityperiod

Encryptionkeyscannotbeusedindefinitely.Thereareseveralreasons:thelongerthekeyisused,thegreaterthechanceofitbeingleaked;ifthekeyisHasbeenleaked,thenthelongerthekeyisused,thegreatertheloss;thelongerthekeyisused,thegreaterthetemptationforpeopletospendenergydecipheringit-evenbruteforceattacks;formultipleciphertextsencryptedwiththesamekeyItisgenerallyeasiertoperformcryptanalysis.

Differentkeysshouldhavedifferentvalidityperiods.

Thevalidityperiodofthedatakeymainlydependsonthevalueofthedataandtheamountofencrypteddatainagiventime.Thegreaterthevalueandthedatatransferrate,themorefrequentlythekeysusedwillbereplaced.

Keyencryptionkeysdonotneedtobechangedfrequently,becausetheyareonlyusedoccasionallyforkeyexchange.Insomeapplications,thekeyencryptionkeyisonlychangedonceamonthorayear.

Theencryptionkeyusedtoencryptthesaveddatafilecannotbechangedfrequently.Usuallyeachfileisencryptedwithauniquekey,andthenallkeysareencryptedwithakeyencryptionkey.Thekeyencryptionkeyiseithermemorizedorstoredinasafeplace.Ofcourse,losingthiskeymeanslosingallfileencryptionkeys.

Thevalidityperiodoftheprivatekeyinthepublickeycryptographyapplicationvariesaccordingtotheapplication.Theprivatekeyusedfordigitalsignatureandidentificationmustlastforseveralyears(orevenlife),andtheprivatekeyusedforthecointossprotocolshouldbedestroyedimmediatelyaftertheagreementiscompleted.Evenifthesecurityofthekeyisexpectedtolastforalifetime,itisnecessarytoconsiderchangingthekeyonceeverytwoyears.Theoldkeystillneedstobekeptsecretincasetheuserneedstoverifytheprevioussignature.Butthenewkeywillbeusedtosignthenewfiletoreducethenumberofsignaturefilesthatacryptanalystcanattack.

Унищожете ключа

Ако ключът трябва да бъде заменен, старият ключ трябва да бъде унищожен и ключът трябва да бъде физически унищожен.

Система за управление

Паролата за publickey прави ключа по-лесен за управление. Без значение колко хора има в мрежата, всеки има само един publickey.

Itisnotenoughtouseapublic/privatekeypair.Theimplementationofanygoodpublickeycryptographyneedstoseparatetheencryptionkeyfromthedigitalsignaturekey.Butasinglepairofencryptionandsigningkeysisnotenough.LikeanIDcard,aprivatekeyprovesarelationship,andpeoplehavemorethanonerelationship.Forexample,Alicecansignadocumentinthenameofaprivateperson,thevicepresidentofthecompany,etc.

InthefinancialICcardjointpilotprojectsofcommercialbanks,thesecuritycontrolandmanagementofkeysbybanksatalllevelsisthekeytothesecurityoftheapplicationsystem.

"RT-KMSKeyManagement System" следва "ChinaFinancialIntegratedCircuit(IC)CardSpecification(v1.0)"и"BankICCardJointPilotTechnicalPlan"за улесняване на независимостта на банките-членки

Издаване на карти, реализиране на споделянето на четци на карти и завършване на междубанкови транзакции на различни места.

Securitymechanism

InthenationalbankICcardjointpilotprogram,banksatalllevelsusekeymanagementsystemstoimplementkeysecuritymanagement.Thekeymanagementsystemadoptsthe3DESencryptionalgorithmandusesthethree-levelmanagementsystemofthebankheadoffice,theregionalbranchofthePeople’sBankofChina(commercialbankheadoffice),andmemberbankstosecurelysharethepublicmasterkeyandrealizecardintercommunication.,Equipmentsharing.

Theentiresecuritysystemstructuremainlyincludesthreetypesofkeys:thenationally-usedconsumer/cashwithdrawalmasterkeyGMPKoftheheadoffice,theconsumption/cashwithdrawalmasterkeyMPKoftheissuingbank,andothersoftheissuingbank

Главен ключ. Според предназначението на ключа системата приема различни стратегии за обработка.

Принципи на проектиране

(1) Всички ключове са заредени и импортирани в кодиран текст.

(2)Ключът подлежи на строг контрол на авторитета и различни организации или персонал имат различни правомощия за четене, писане, актуализиране и използване на различни ключове.

(3)Inordertoensurethesecurityofkeyuseandconsidertheneedsofactualuse,thesystemcangeneratemultiplesetsofmasterkeys.Ifoneofthekeysisleakedorattacked,theapplicationsystemcanbestoppedimmediatelyTheuseofthissetofkeysandtheuseofbackupkeys,soastoavoidthewasteofexistinginvestmentandequipmentasmuchaspossible,andreducetheriskofsystemuse.

(4)Userscanchoosedifferentcombinationsandconfigurationsofthekeymanagementsubsystemaccordingtoactualneeds.

(5) Ключовата услуга, съхранението и архивирането са във формата на ключ за криптираща машина.

Managementtechnology

Technologyclassification

1.Symmetrickeymanagement.Symmetricencryptionisrealizedbasedonthecommonkeepingofsecrets.Bothpartiestothetradethatadoptsymmetricencryptiontechnologymustensurethattheyusethesamekey,thattheexchangeofeachother'skeysissafeandreliable,andalsosetupprocedurestopreventkeyleakageandchangekeys.Inthisway,themanagementanddistributionofsymmetrickeyswillbecomeapotentiallydangerousandcumbersomeprocess.Therealizationofsymmetrickeymanagementthroughpublickeyencryptiontechnologymakesthecorrespondingmanagementsimplerandmoresecure,andatthesametimesolvesthereliabilityandauthenticationproblemsinthepuresymmetrickeymode.Thetradingpartycangenerateauniquesymmetrickeyforeachexchangeofinformation(suchaseachEDIexchange)andencryptthekeywithapublickey,andthenencrypttheencryptedkeywiththekeyTheinformation(suchasEDIexchange)issenttothecorrespondingtradingpartytogether.Sinceauniquekeyisgeneratedforeachinformationexchange,eachtradingpartynolongerneedstomaintainthekeyandworryabouttheleakageorexpirationofthekey.Anotheradvantageofthismethodisthatevenifakeyisleaked,itwillonlyaffectonetransaction,andwillnotaffectallthetransactionrelationshipsbetweenthetradingparties.Thismethodalsoprovidesasecurewaytoissuesymmetrickeysbetweentradingpartners.

2.Publickeymanagement/digitalcertificate.Digitalcertificates(publickeycertificates)canbeusedtoexchangepublickeysbetweentradingpartners.ThestandardX.509developedbytheInternationalTelecommunicationUnion(ITU)definesdigitalcertificates.ThisstandardisequivalenttotheISO/IEC9594-8:195standardjointlyissuedbytheInternationalOrganizationforStandardization(ISO)andtheInternationalElectrotechnicalCommission(IEC).Digitalcertificatesusuallyincludethenamethatuniquelyidentifiestheownerofthecertificate(ie,thetradingparty),thenamethatuniquelyidentifiesthecertificateissuer,thepublickeyofthecertificateowner,thedigitalsignatureofthecertificateissuer,thevalidityperiodofthecertificate,andtheserialnumberofthecertificate,etc..Thecertificateissuerisgenerallycalledacertificateauthority(CA),whichisanorganizationtrustedbyallpartiesinthetrade.Digitalcertificatescanplayaroleinidentifyingtradingpartiesandarecurrentlyoneofthetechnologieswidelyusedine-commerce.

3.Standardspecificationsrelatedtokeymanagement.Atpresent,relevantinternationalstandardizationorganizationshavestartedtoformulatetechnicalstandardsandspecificationsonkeymanagement.TheInformationTechnologyCommittee(JTC1)underISOandIEChasdraftedaninternationalstandardspecificationforkeymanagement.Thespecificationismainlycomposedofthreeparts:oneisthekeymanagementframework;thesecondisthemechanismusingsymmetrictechnology;thethirdisthemechanismusingasymmetrictechnology.Thespecificationhasnowenteredthestageofvotingondraftinternationalstandardsandwillsoonbecomeanofficialinternationalstandard.

Цифров подпис

Digitalsignatureisanothertypeofapplicationofpublickeyencryptiontechnology.Itsmainmethodis:thesenderofthemessagegeneratesa128-bithashvalue(ormessagedigest)fromthemessagetext.Thesenderusesitsownprivatekeytoencryptthishashvaluetoformthesender'sdigitalsignature.Then,thisdigitalsignaturewillbesenttotherecipientofthemessageasanattachmenttothemessagetogetherwiththemessage.Thereceiverofthemessagefirstcalculatesa128-bithashvalue(ormessagedigest)fromthereceivedoriginalmessage,andthenusesthesender'spublickeytodecryptthedigitalsignatureattachedtothemessage.Ifthetwohashvalues​​arethesame,thereceivercanconfirmthatthedigitalsignatureisfromthesender.Throughthedigitalsignature,theauthenticationandnon-repudiationoftheoriginalmessagecanberealized.

ISO/IECJTC1isalreadydraftingrelevantinternationalstandards.Thepreliminarytitleofthestandardis"InformationTechnologySecurityTechnologywithAttachedDigitalSignatureScheme",whichconsistsoftwoparts:anoverviewandanidentity-basedmechanism.

Алгоритъм за шифроване

Въведение в криптографията. Според записите през 400 г. пр. н. е. древните гърци са изобретили заместващ шифър. През 1881 г. се появява първият в света патент за телефонна сигурност. По време на Втората световна война германските военни са използвали криптографската машина „Енигма“ и криптографията е имала голямо значение.

Withthedevelopmentofinformationtechnologyanddigitalsociety,people’sawarenessoftheimportanceofinformationsecurityandconfidentialitycontinuestoincrease,soin1997,theNationalBureauofStandardsannouncedtheimplementationofthe"USDataEncryptionStandard(DES)"Thecivilforcesbegantofullyinterveneintheresearchandapplicationofcryptography,usingencryptionalgorithmssuchasDES,RSA,andSHA.Asthedemandforencryptionstrengthcontinuestoincrease,AESandECChaverecentlyappeared.

Usingcryptographycanachievethefollowingpurposes:

Поверителност: Предотвратете прочитането на идентификацията или данните на потребителя.

Целостта на данните: Предотвратяване на промяна на данните.

Потвърждение на самоличността: за да се гарантира, че данните са изпратени от конкретна страна.

2.IntroductiontoencryptionalgorithmsAccordingtodifferentkeytypes,moderncryptographictechnologiesaredividedintotwocategories:symmetricencryptionalgorithms(secretkeyencryption)andasymmetricencryptionalgorithms(publickeyencryption).

Thesymmetrickeyencryptionsystemusesthesamesecretkeyforencryptionanddecryption,andbothpartiesincommunicationmustobtainthiskeyandkeepthekeysecret.

Ключът за криптиране (publickey) и ключът за декриптиране (privatekey), използвани от системата за криптиране с асиметричен ключ, са различни.

Symmetricencryptionalgorithm

Inasymmetricencryptionalgorithm,onlyonekeyisusedtoencryptanddecryptinformation,thatis,thesamekeyisusedforencryptionanddecryption.Commonlyusedalgorithmsinclude:DES(DataEncryptionStandard):adataencryptionstandard,whichisfasterandissuitableforencryptinglargeamountsofdata.

3DES(TripleDES):Въз основа на DES, част от данните се криптират три пъти с три различни ключа, с по-висока якост.

AES(AdvancedEncryptionStandard):AdvancedEncryptionStandard,стандарт за алгоритъм за криптиране от следващо поколение,с бърза скорост ивисоко ниво на сигурност;

InOctober2000,NIST(AmericanNationalStandardAndTechnologyAssociation)announcedtheadoptionofanewkeyencryptionstandardselectedfrom15candidatealgorithms.RijndaelwasselectedasthefutureAES.Rijndaelwasfoundedinthesecondhalfof1999byresearchersJoanDaemenandVincentRijmen.AESisincreasinglybecomingthedefactostandardforencryptingvariousformsofelectronicdata.

Националният институт за стандарти и технологии (NIST) формулира нова спецификация на Advanced Encryption Standard (AES) на 26 май 2002 г.

AlgorithmprincipleTheAESalgorithmisbasedonpermutationandpermutationoperations.Permutationistorearrangedata,andreplacementistoreplaceonedataunitwithanother.AESusesseveraldifferentmethodstoperformpermutationandpermutationoperations.

AESisaniterative,symmetrickeyblockcipher,itcanuse128,192,and256-bitkeys,anduse128-bit(16-byte)blockstoencryptanddecryptdata.Unlikepublickeyciphersthatusekeypairs,symmetrickeyciphersusethesamekeytoencryptanddecryptdata.Thenumberofbitsoftheencrypteddatareturnedbytheblockcipheristhesameastheinputdata.Iterativeencryptionusesaloopstructureinwhichtheinputdataisrepeatedlyreplacedandreplaced.

Сравнение между AES и 3DES

Асиметричен алгоритъм

Обикновените алгоритми за симетрично криптиране са както следва:

RSA:InventedbyRSA,itisapublickeyalgorithmthatsupportsvariable-lengthkeys.Thelengthofthefileblockthatneedstobeencryptedisalsovariable;

p>

DSA(DigitalSignatureAlgorithm):Алгоритъм за цифров подпис,isstandardDSS(DigitalSignatureStandard);

ECC(Криптография на елиптични криви):Криптография на елиптични криви.

In1976,becausesymmetricencryptionalgorithmscouldnolongermeettheneeds,DiffieandHellmanpublishedanarticlecalled"NewTrendsinCryptography",whichintroducedtheconceptofpublickeyencryption.AdelmanproposedtheRSAalgorithm.

Withtheprogressandimprovementofthemethodofdecomposinglargeintegers,theincreaseofcomputerspeedandthedevelopmentofcomputernetworks,inordertoensurethesecurityofdata,theRSAkeyneedstoincreasecontinuously.However,theincreaseofthekeylengthleadstoAsthespeedofencryptionanddecryptionhasbeengreatlyreduced,hardwareimplementationhasbecomemoreandmoreunbearable,whichhasbroughtaheavyburdentoapplicationsthatuseRSA,soanewalgorithmisneededtoreplaceRSA.

In1985,N.KoblitzandMillerproposedtheuseofellipticcurvesincryptographicalgorithms,basedonthediscretelogarithmproblemECDLPinpointgroupsonellipticcurvesoverfinitefields.ECDLPisamoredifficultproblemthanthefactorizationproblem,itisexponentiallydifficult.

Principle-thedifficultproblemontheellipticcurveThediscretelogarithmproblemontheellipticcurveECDLPisdefinedasfollows:GivenaprimenumberpandanellipticcurveE,forQ=kP,findPandQFindapositiveintegerkthatislessthanp.ItcanbeprovedthatitiseasiertocalculateQfromkandP,butitismoredifficulttocalculatekfromQandP.

Correspondingtheadditionoperationintheellipticcurvetothemodularmultiplicationoperationinthediscretelogarithm,andthemultiplicationoperationintheellipticcurvecorrespondingtothemodularexponentiationoperationinthediscretelogarithm,wecanbuildbasedonThecorrespondingcryptosystemoftheellipticcurve.

Forexample,correspondingtotheDiffie-Hellmanpublickeysystem,wecanimplementitontheellipticcurveinthefollowingway:selectthegeneratorPonE,andrequireenoughgroupelementsgeneratedbyP,andthecommunicationpartiesAAndBselectsaandbrespectively,aandbarekeptsecret,butaPandbParemadepublic,andthekeyusedforcommunicationbetweenAandBisabP,whichisnotknowntoathirdparty.

ThecorrespondingELGamalcryptosystemcanbeimplementedontheellipticcurveinthefollowingway:

Вградете обикновения текст в точката Pm на E, изберете точка B∈E и всеки потребител изберете цяло число,0

K=kG[къдетоK,GarepointsonEp(a,b),иkisintegerless thann(nistheorderofpointG)]

ItisnotdifficulttofindthatgivenkandG,itiseasytocalculateKaccordingtotheruleofaddition;butgivenKandG,itisrelativelydifficulttofindk.

Това е проблемът, който създава алгоритъмът за криптиране на елиптичната крива. Ние наричаме точката Gбазова точка, k(privtekey) и Kпубличният ключ.

ComparisonofECCandRSAComparedwithECCandRSA,Hasabsoluteadvantagesinmanyaspects,mainlyreflectedinthefollowingaspects:

Силна анти-атака. Същата дължина на ключа, неговата анти-атака е многократно по-силна.

Theamountofcalculationissmallandtheprocessingspeedisfast.TheoverallspeedofECCismuchfasterthanthatofRSAandDSA.

Thestoragespaceissmall.ThekeysizeandsystemparametersofECCaremuchsmallerthanthoseofRSAandDSA.More,itmeansthatitoccupiesamuchsmallerstoragespace.ThisisofspecialsignificancefortheapplicationofencryptionalgorithmsonICcards.

Lowbandwidthrequirements.WhenencryptinganddecryptinglongmessagesAtthistime,thethreetypesofcryptosystemshavethesamebandwidthrequirements,butwhenappliedtoshortmessages,theECCbandwidthrequirementsaremuchlower.ThelowbandwidthrequirementsmakeECChaveawiderangeofapplicationprospectsinthefieldofwirelessnetworks.

ECCThesecharacteristicsmakeitsuretoreplaceRSAandbecomeageneralpublickeyencryptionalgorithm.Forexample,thecreatorsoftheSETprotocolhaveadopteditasthedefaultpublickeyencryptionalgorithminthenextgenerationSETprotocol.

ThefollowingtwoRepresentsthecomparisonofthesecurityandspeedofRSAandECC.

Сравняване на RSA и ECC модули за сигурност

Сравнение на скоростта между RSA и ECC

Hashalgorithm

Hashingalgorithmisalsocalledhashalgorithm,EnglishisHash,whichistotransformaninputofanylength(alsocalledpre-image,pre-image)intoafixed-lengthoutputthroughahashingalgorithm.Theoutputisthehashvalue.Thisconversionisacompressionmapping,thatis,thehashvaluespaceisusuallymuchsmallerthantheinputspace,differentinputsmaybehashedintothesameoutput,anditisimpossibletouniquelydeterminetheinputvaluefromthehashvalue.Simplyput,itisafunctionthatcompressesmessagesofanylengthtoafixed-lengthmessagedigest.

HASHismainlyusedinencryptionalgorithmsinthefieldofinformationsecurity.Itconvertsinformationofdifferentlengthsintomessy128-bitcodes.Thesecodedvalues​​arecalledHASHvalues.ItcanalsobesaidthathashistofindakindofThehashofthemappingrelationshipbetweenthedatacontentandthedatastorageaddressistherefinementoftheinformation,anditslengthisusuallymuchsmallerthanthatoftheinformation,anditisafixedlength.Astrongencryptionhashmustbeirreversible,whichmeansthatnopartoftheoriginalinformationcanbederivedfromthehashresult.Anychangeintheinputinformation,evenifitisonlyonebit,willcauseasignificantchangeinthehashresult,whichiscalledtheavalancheeffect.Hashingshouldalsobeanti-collision,thatis,twopiecesofinformationwiththesamehashresultcannotbefound.Thehashresultwiththesecharacteristicscanbeusedtoverifywhethertheinformationhasbeenmodified.

Еднопосочната функция за хеширане обикновено се използва за генериране на обобщени съобщения, криптиране на ключове и т.н. Общите са:

MD5(MessageDigestAlgorithm5): Разработено е от RSADataSecurityCorporationAone-wayhashalgorithm.

SHA(SecureHashAlgorithm): Може да генерира 160-битова стойност за дължина на данните;

In1993,theSecureHashAlgorithm(SHA)wasadoptedbytheAmericanNationalStandardItwasproposedbytheInstituteofTechnologyandTechnology(NIST)andpublishedastheFederalInformationProcessingStandard(FIPSPUB180);in1995,arevisedversionofFIPSPUB180-1wasreleased,usuallycalledSHA-1.SHA-1isbasedontheMD4algorithm,anditsdesignlargelyimitatesMD4.Itisnowrecognizedasoneofthesafesthashingalgorithmsandiswidelyused.

PrincipleSHA-1isadataencryptionalgorithm.Theideaof​​thealgorithmistoreceiveapieceofplaintextandthenconvertitintoapieceof(usuallysmaller)ciphertextinanirreversibleway.ItcanalsobesimpleTheunderstandingofistheprocessoftakingastringofinputcodes(calledpre-mappingorinformation)andconvertingthemintoashort-length,fixed-digitoutputsequencethatisahashvalue(alsoknownasinformationdigestorinformationauthenticationcode).

Thesecurityoftheone-wayhashfunctionliesinitsstrongone-wayoperationintheprocessofgeneratingthehashvalue.Ifthepasswordisembeddedintheinputsequence,noonecangeneratethecorrecthashvaluewithoutknowingthepassword,thusensuringitssecurity.SHAdividestheinputstreamintoblocksof512bits(64bytes)perblock,andproduces20bytesofoutputcalledthemessageauthenticationcodeormessagedigest.

Максималната дължина на въведеното съобщение на алгоритъма не надвишава 264 бита, а изходът е 160-битово обобщено съобщение. Входът се обработва в 512-битови групи. SHA-1 е необратим, против сблъсък и има добър лавинообразен ефект.

Thedigitalsignaturecanberealizedthroughthehashalgorithm.Theprincipleofdigitalsignatureistoconverttheplaintexttobetransmittedintoamessagedigestthroughafunctionoperation(Hash)(differentplaintextcorrespondstodifferentmessagedigests),Themessagedigestisencryptedandsenttotherecipienttogetherwiththeplaintext.Therecipientwillgenerateanewmessagedigestofthereceivedplaintextandcompareitwiththesender'ssentmessagedigest.Thecomparisonresultisconsistent,indicatingthattheplaintexthasnotbeenchanged.Ifitisinconsistent,itmeansTheplaintexthasbeentamperedwith.

MAC(InformationAuthenticationCode)isahashresult.Partoftheinputinformationisapassword.OnlyparticipantswhoknowthispasswordcanrecalculateandverifythevalidityoftheMACcode.ThegenerationofMACisshowninthefigurebelow.

Сравнение между SHA-1 и MD5, тъй като и двете са получени от MD4, и SHA-1 и MD5 са много различни от всяка друга.прилика.

Securityagainstforcedsupply:ThemostsignificantandimportantdifferenceisthattheSHA-1abstractislongerthantheMD5abstract32bits.Usingforcetechnology,thedifficultyofgeneratinganymessagesothatitsdigestisequaltoagivendigestisa2-orderoperationforMD5,anda2-orderoperationforSHA-1.Inthisway,SHA-1hasgreaterstrengthagainstforcedattacks.

Сигурност на криптирания анализ: Благодарение на дизайна на MD5 е уязвим на атаки на криптиран анализ и SHA-1 не е уязвим на такива атаки.

Скорост: На същия хардуер SHA-1 работи по-бавно от MD5.

Сравнение на двата

Сравнение на симетрични и асиметрични алгоритми

Theprinciplesofthetwoencryptionmethodsaresummarizedabove.Generallyspeaking,therearemainlythefollowingaspectsDifferent:

1.Intermsofmanagement:thepublickeycryptographicalgorithmonlyneedslessresourcestoachieveitspurpose.Inthedistributionofkeys,thereisanexponentialleveldifferencebetweenthetwo(oneisnoneIsn).Therefore,theprivatekeycryptographicalgorithmisnotsuitablefortheuseofWAN,andmoreimportantly,itdoesnotsupportdigitalsignatures.

2.Intermsofsecurity:Sincethepublickeycryptographicalgorithmisbasedonanunsolvedmathematicalproblem,itisalmostimpossibletocrack.Fortheprivatekeycryptographicalgorithm,althoughitisimpossibletocracktheoreticallybyAES,fromtheperspectiveofcomputerdevelopment.Thepublickeyismoreadvantageous.

3.Fromthepointofviewofspeed:ThesoftwareimplementationspeedofAEShasreachedseveralmegabitsortensofmegabitspersecond.Itis100timesthepublickey.Ifimplementedbyhardware,thisratiowillbeexpandedto1000times.

ThechoiceofencryptionalgorithmThepreviouschaptershaveintroducedsymmetricdecryptionalgorithmsandasymmetricencryptionalgorithms.Manypeoplearewondering:Sowhichoneshouldweuseinactualuseisbetter?

Weshoulddetermineaccordingtoourowncharacteristics.Sincetherunningspeedofasymmetricencryptionalgorithmismuchslowerthanthatofsymmetricencryptionalgorithm,whenweneedtoencryptalargeamountofdata,itisrecommendedtousesymmetricencryptionalgorithmtoimproveEncryptionanddecryptionspeed.

Symmetricencryptionalgorithmcannotrealizesignature,sosignaturecanonlybeasymmetricalgorithm.

Asthekeymanagementofthesymmetricencryptionalgorithmisacomplexprocess,themanagementofthekeydirectlydeterminesitssecurity,sowhentheamountofdataissmall,wecanconsiderusinganasymmetricencryptionalgorithm.

Intheactualoperationprocess,weusuallyadoptthemethod:useanasymmetricencryptionalgorithmtomanagethekeyofthesymmetricalgorithm,andthenusethesymmetricencryptionalgorithmtoencryptthedata,sothatwehaveintegratedtwotypesofencryptionalgorithmsTheadvantageofnotonlyrealizestheadvantagesoffastencryptionspeed,butalsorealizestheadvantagesofsafeandconvenientkeymanagement.

Ако алгоритъмът за криптиране е избран погрешно, колко бита ключ трябва да се използва? Най-общо казано, колкото по-дълъг е ключът, толкова по-ниска е скоростта на работа. Той трябва да бъде избран в съответствие с нивото на сигурност, което действително се нуждае.

Themodernapplicationofcryptography,withthepopularizationofcommercialapplicationsofcryptography,publickeycryptographyhasreceivedunprecedentedattention.Inadditiontotraditionalcryptographicapplicationsystems,thePKIsystemisbasedonpublickeycryptography,providingfunctionssuchasencryption,signature,authentication,keymanagement,anddistribution.

Confidentialcommunication:Confidentialcommunicationisthecauseofcryptography.Whenusingpublicandprivatekeycryptographyforconfidentialcommunication,therecipientoftheinformationcandecrypttheinformationonlyifheknowsthecorrespondingkey.

Digitalsignature:Digitalsignaturetechnologycanreplacetraditionalhandwrittensignatures,andfromasecurityperspective,digitalsignatureshaveagoodanti-counterfeitingfunction.Ithasawiderangeofapplicationenvironmentsingovernmentagencies,militaryfields,andcommercialfields.

Secretsharing:Secretsharingtechnologyreferstotheuseofcryptographictechniquestosplitasecretinformationintonpiecesofinformationcalledsharingfactors,anddistributethemtonmembers,onlyk(k≤n)legalmembersThesecretinformationcanberecoveredbythesharingfactorof,andanyoneorm(m≤k)memberscooperateswithoutknowingthesecretinformation.Theuseofsecretsharingtechnologycancontrolanysecretinformation,commands,etc.thatneedtobecontrolledbymultiplepeople.

Authenticationfunction:transmitsensitiveinformationonopenchannels,usesignaturetechnologytoverifytheauthenticityandintegrityofthemessage,andverifytheidentityofthecommunicationsubjectbyverifyingthepublickeycertificate.

Keymanagement:Thekeyisamorefragileandimportantlinkinthesecuritysystem.Thepublickeycryptosystemisapowerfultooltosolvethekeymanagementwork;thepublickeycryptosystemisusedforkeynegotiationandgeneration,Thetwopartiesinconfidentialcommunicationdonotneedtosharesecretinformationinadvance;publickeycryptosystemsareusedforkeydistribution,protection,keyescrow,andkeyrecovery.

Basedonthepublickeycryptosystem,inadditiontotheabovegeneralfunctions,thefollowingsystemscanalsobedesignedandimplemented:securee-commercesystem,electroniccashsystem,electronicelectionsystem,electronicbiddingsystem,electroniclotterysystem,etc.

Theemergenceofthepublickeycryptosystemisthebasisforthedevelopmentofcryptographyfromthetraditionalgovernment,militaryandotherapplicationfieldstocommercialandcivilianuse.Atthesametime,thedevelopmentoftheInternetande-commercehasopenedupabroaderfieldforthedevelopmentofcryptography.prospect.

ThefutureofencryptionalgorithmsWiththeimprovementofcalculationmethods,theaccelerationofcomputeroperationspeed,andthedevelopmentofnetworks,moreandmorealgorithmshavebeencracked.

Atthe2004InternationalConferenceonCryptography(Crypto'2004),ProfessorWangXiaoyunfromShandongUniversity,China,madeareportondecipheringMD5,HAVAL-128,MD4andRIPEMDalgorithms,whichmadethepresentinternationaltoppasswordsAcademicexpertsareshocked,whichmeansthatthesealgorithmswillbeeliminatedfromtheapplication.Subsequently,SHA-1wasalsodeclaredtohavebeencracked.

TherearethreeattackexperimentsthathaveanimpactonDESinhistory.In1997,using70,000computersfromvariouscountriesatthattime,ittook96daystocracktheDESkey.In1998,theElectronicFrontierFoundation(EFF)usedaspecialcomputerbuiltfor$250,000tocracktheDESkeyin56hours.In1999,EFFcompletedthecrackingworkin22hoursand15minutes.therefore.DES,whichoncemadeoutstandingcontributions,cannolongermeetourgrowingneeds.

Recently,agroupofresearcherssuccessfullydecomposeda512-bitintegerandannouncedtheRSAcracking.

Wesaythatdatasecurityisrelative.Itcanbesaidthatitissafeforacertainperiodoftimeandundercertainconditions.Withthedevelopmentofhardwareandnetwork,ortheemergenceofanotherWangXiaoyun,thecurrentcommonlyusedencryptionalgorithmsareItmaybecrackedinashorttime.Atthattime,wehavetouselongerkeysormoreadvancedalgorithmstoensuredatasecurity.Therefore,encryptionalgorithmsstillneedtobecontinuouslydevelopedandimprovedtoprovidehigherencryptionsecuritystrengthandcalculatingspeed.

Overviewofthesetwoalgorithms,oneisfromDESto3DEStoAES,andtheotherisfromRSAtoECC.Itsdevelopmentangleisallconsideringthesimplicityofthekey,thelowcost,theeaseofmanagement,thecomplexityofthealgorithm,thesecurityofconfidentiality,andthespeedofcalculation.Therefore,thedevelopmentofalgorithmsinthefuturemustbebasedontheseperspectives,andthesetwoalgorithmsareoftencombinedinactualoperations,andanewalgorithmthatcombinestheadvantagesofthetwoalgorithmswillappearinthefuture.Atthattime,therealizationofe-commercewillsurelybefasterandsafer.