overview why java is secure

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1、Overview•WhyJavaissecureEvolutionofJavaSecurity•JDK1.0securitymodel•JDK1.1.xsecuritymodel•JDK1.2securitymodelOlgaKornievskaiaWhyisJavasecure?WhyisJavasecure(cont.)•Completesourcecodeispublished•Garbagecollection:avoidscommonbugs•Well-definedlanguage–failingtofreememoryonceisnolongerneeded–a

2、llprimitivetypesareofaspecificsize–accidentlyfreeingthesamememorytwice–alloperationsperformedinaspecificorder•Compile-TimeChecking•Nopointers–explicitruntimecheckforcastingobjects–nopointerarithmetic–allreferencesarecheckedforvalidity–allreferencesviasymbolicnames•accessofuninitializedvaria

3、bles•referencingaprivatevariable/methodWhyisJavasecure(cont.)WhyisJavasecure(cont.)•Bytecodeverifier:•SecurityManager:–stackoverflows–enforcesboundariesaroundthesandbox–invalidregisteraccessesandstores–consultedoneachprivilegedaction–invalidparameterstobytecodeinstructions–loadedatstart-up,

4、can’tbeextended,–illegaldataconversionoverriddenorreplaced.•Classloader:–definesalocalnamespace1Inshort...OriginalSecurityModel•Well-defined,type-safelanguage•Localcodeistrustedtohavefullaccess•Checksbycompiler•Downloadedcodeis•Checksbyverifiernottrusted•ChecksbySecurityManagerWhatappletsCA

5、N’Tdo?ExtendedSecurityModel•Read,write,orgetinformationaboutafile•JDK1.1.xintroducedsignedapplets•executeOScommandsornativecode•Signedappletsgain•loadlibrariesfullaccesstosystem•establishnetworkconnectiontoanyresourcesmachineotherthanapplet’shostmachine•Unsignedappletsstilltreatedasuntruste

6、dappletsExtendedSecurityModelCapabilitiesBasedModel•Microsoft:Trust-based•Netscape:Capabilities•Principle:representsthe“who”SecurityModelModel•Target:representsthe“what”–allpermissionsare–queryusersasgrantedup-frontpermissionsarerequested•Privilege:denies/authorizestoaccessTargetby–mostofth

7、etime,no–codemodificationisPrincipleadditionalcodeisneededalwaysrequired•PrivilegeManager:trackswhichprinciplesare–threelevelsofaccess–fine-grainedaccessallowedtoaccesswhichtargetscontrolcontrol2NetscapesecuritystepsTodownloadaJARfile•Modifyyourapplicati