简介：Theonlinesocialnetworks(OSNs)offerattractivemeansforsocialinteractionsanddatasharing,aswellasraiseanumberofsecurityandprivacyissues.Althoughcurrentsolutionsproposetoencryptdatabeforesharing,theaccesscontrolofencrypteddatahasbecomeachallengingtask.Moreover,multipleownersmayenforcedifferentaccesspolicytothesamedatabecauseoftheirdifferentprivacyconcerns.Adigitalrightsmanagement(DRM)schemeisproposedforencrypteddatainOSNs.Inordertoprotectusers'sensitivedata,theschemeallowsusersoutsourceencrypteddatatotheOSNsserviceproviderforsharingandcustomizetheaccesspolicyoftheirdatabasedonciphertext-policyattribute-basedencryption.Furthermore,theschemepresentsamultipartyaccesscontrolmodelbasedonidentity-basedbroadcastencryptionandciphertext-policyattribute-basedproxyre-encryption,whichenablesmultipleowners,suchastaggeduserswhoappearinasingledata,customizetheaccesspolicycollaboratively,andalsoallowsthedisseminatorsupdatetheaccesspolicyiftheirattributessatisfytheexistingaccesspolicy.Securityanalysisandcomparisonindicatethattheproposedschemeissecureandefficient.