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标准模型下基于强RSA假设的身份签名方案 1.Introduction Thestandardmodelofcryptographyrestsonseveralassumptions,includingthestrongRSAassumption.ThisassumptionpositsthatitisinfeasibleforanadversarytodetermineanRSAprivatekeygivenonlythecorrespondingpublickey.Inthispaper,weexploretheuseofthestrongRSAassumptioninthecontextofidentity-basedsignatureschemes. Anidentity-basedsignatureschemeallowsasignertosignmessagesusinganarbitrarystringasthepublickey.Thisstringistypicallyauser'sidentity,suchasanemailaddressorausername.Thesignergeneratesaprivatekeythatistiedtothisidentity,allowingthemtosignmessagesthatcanbeverifiedbyanyonewhoknowsthecorrespondingpublickey. 2.StrongRSAAssumption ThestrongRSAassumptionisatypeofone-wayfunctionthatisusedinmanycryptographicprotocols.ItpositsthatgiventhepublickeyNandanarbitraryelementMinZ_N,itiscomputationallyinfeasibletodeterminethecorrespondingprivatekeydsuchthatM^d≡MmodN. Thisassumptionisusedinmanycryptographicprotocols,includingdigitalsignatureschemes,encryptionschemes,andkeyexchangeprotocols.Inthecontextofidentity-basedsignatureschemes,thestrongRSAassumptionisusedtoensurethattheprivatekeyassociatedwithauser'sidentitycannotbecomputedwithoutknowledgeofthecorrespondingpublickey. 3.Identity-BasedSignatureSchemes Identity-basedsignatureschemeswerefirstproposedbyAdiShamirin1984.Inthisscheme,ausergeneratesapublickeybasedontheiridentityandamastersecretkeygeneratedbyatrustedparty.Themastersecretkeyisusedtogeneratetheprivatekeysassociatedwitheachuser'sidentity. Thesignergeneratesasignaturebyapplyingamathematicaloperationtothemessageandtheirprivatekey.Thissignaturecanbeverifiedbyanyonewhoknowsthecorrespondingpublickey.Inordertoverifythesignature,theverifiermustcalculateavalueusingthemessage,thesignature,andthepublickey. Thesecurityofidentity-basedsignatureschemesreliesonthestrongRSAassumption.Withoutthisassumption,anadversarycouldcomputetheprivatekeyassociatedwithauser'sidentitywithoutknowledgeofthecorrespondingpublickey. 4.SecurityofIdentity-BasedSignatureSchemesUsingth