Chapter 2 Public-Key Cryptograph.ppt
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Chapter 2 Public-Key Cryptograph.ppt

Chapter2Public-KeyCryptograph.ppt

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PKIPrincipleandTechnology思考题Chapter2Public-KeyCryptography本章重要知识点1AsymmetricCryptographyWhyPublic-KeyCryptography?1AsymmetricCryptographyPublic-KeyCryptographyPrinciplesApplicationsforPublic-KeyCryptosystemsPublicKeyEncryptionModelRequirementsforPublic-KeyCryptographyRequirementsforPublic-KeyCryptographyPublic-keyCryptosystemEncryptionusingPublic-KeysystemAuthenticationusingPublic-KeySystemPublic-KeyCryptographicAlgorithmsRSAOtherPublic-KeyCryptographicAlgorithms1AsymmetricCryptography1AsymmetricCryptographyHybridEncryption(混合加密RealWorld)1AsymmetricCryptography1AsymmetricCryptography*#$fjda^ju539!3tt389E*&\@5e%32\^kd1AsymmetricCryptographyHashingisthemethodusedtoobtaina"digitalfingerprint"(hash)foragivenmessage,whichmaybeusedtovalidatethemessageintegritybutnottoreproduceit.Thehashcodehasafixed-length(normally128or160bits)andit'sdesignedtobeunique(differentmessagesproducedifferenthashes).Hashingalgorithmsarealsocalledone-wayhashfunctions,messagedigestalgorithms,cryptographicchecksum,digitalfingerprint,messageintegrityLength-reducingfunctionhMaparbitrarystringstostringsoffixedlengthOneway(“preimageresistance”)Giveny,hardtofindxwithh(x)=yCollisionresistantHardtofindanydistinctm,m’withh(m)=h(m’)Alsouseful:2ndpreimage(原相)resistanceGivenx,hardtofindx’xwithh(x’)=h(x)Collisionresistance2ndpreimageresistanceApplicationsofone-wayhashSubsequentdevelopments3DigitalSignaturesPropertiesofsignaturesCreatingaDigitalSignatureVerifyingaDigitalSignature4DigitalCertificatesWhatisaCertificate?4DigitalCertificates4DigitalCertificatesUsingdigitalcertificatesPlaintextEncrypteddigesttotheplaintextDigitalCertificate4DigitalCertificates5Non-Repudiation