pppl and princeton demonstrate novel technique that … … · · 2016-10-25pppl and princeton...
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PPPLandPrincetondemonstratenoveltechniquethatmayhaveapplicabilitytofuturenucleardisarmamenttalksByJohnGreenwaldSeptember20,2016
GraduatestudentSébastienPhilippewholedthezero-knowledgeprotocolexperiment.(PhotobyElleStarkman/OfficeofCommunications)AsystemthatcancomparephysicalobjectswhilepotentiallyprotectingsensitiveinformationabouttheobjectsthemselveshasbeendemonstratedexperimentallyattheU.S.DepartmentofEnergy’s(DOE)PrincetonPlasmaPhysicsLaboratory(PPPL).Thiswork,byresearchersatPrincetonUniversityandPPPL,marksaninitialconfirmationoftheapplicationofapowerfulcryptographictechniqueinthephysicalworld.
“Thisisthefirstexperimentaldemonstrationofaphysicalzero-knowledgeproof,”saidSébastienPhilippe,agraduatestudentintheDepartmentofMechanicalandAerospaceEngineeringatPrincetonUniversityandleadauthorofthepaper.“Wehavetranslatedamajormethodofmoderncryptographydevisedoriginallyforcomputationaltasksintouseforaphysicalsystem.”Cryptographyisthescienceofdisguisinginformation.Thisresearch,supportedbyfundingfromtheDOE’sNationalNuclearSecurityAdministrationthroughtheConsortiumforVerificationTechnology,marksapromisingfirstexperimentalsteptowardatechniquethatcouldproveusefulinfuturedisarmamentagreements,pendingtheresultsoffurtherdevelopment,testingandevaluation.Whileimportantquestionsremain,thetechnique,firstproposedinapaperpublishedin2014inNature(linkisexternal)magazine,mighthavepotentialapplicationtoverifythatnuclearwarheadspresentedfordisarmamentwereinfacttruewarheads.SupportforthisworkcamealsofromtheJohnD.andCatherineT.MacArthurFoundationandtheCarnegieFoundationofNewYork.Theresearch,outlinedinapaperinNatureCommunicationsonSeptember20,2016,wasconductedonasetof2-inchsteelandaluminumcubesarrangedindifferentcombinations.Researchersfirstorganizedthecubesintoadesignated“true”patternandthenintoanumberof“false”ones.Next,theybeamedhigh-energyneutronsintoeacharrangementandrecordedhowmanypassedthroughtobubbleneutrondetectorsproducedbyYaleUniversity,ontheotherside.Whenaneutroninteractswithasuperheateddropletinthedetector,itcreatesastablemacroscopicbubble.Toavoidrevealinginformationaboutthecompositionandconfigurationofthecubes,bubblescreatedinthismannerwereaddedtothosealreadypreloadedintothedetectors.Thepreloadwasdesignedsothatifavalidobjectwerepresented,thesumofthepreloadandthesignaldetectedwiththeobjectpresentwouldequalthecountproducedbyfiringneutronsdirectlyintothedetectors–withnoobjectinfrontofthem.Theexperimentfoundthatthecountforthe“true”patternequaledthesumofthepreloadandtheobjectwhenneutronswerebeamedwithnothinginfrontofthem,whilethecountforthesignificantlydifferent“false”arrangementsclearlydidnot.“Thiswasanextremelyimportantexperimentaldemonstration,”saidRobertGoldston,afusionscientistandcoauthorofthepaperwhoisformerdirectorofPPPLandaPrincetonprofessorofastrophysicalsciences.“Wehadatheoreticalideaandhavenowprovidedaprovenpracticalexample.”JoininghimascoauthorsareAlexGlaser,associateprofessorinPrinceton’sWoodrowWilsonSchoolofPublicandInternationalAffairsandtheDepartmentofMechanicalandAerospaceEngineering;andFrancescod’Errico,seniorresearchscientistattheYaleSchoolofMedicineandprofessorattheUniversityofPisa,Italy.
Whenfurtherdevelopedforapossiblearmscontrolapplication,thetechniquewouldaddbubblesfromirradiationofaputativewarheadtothosealreadypreloadedintodetectorsbythewarhead’sowner.Ifthetotalforthenewandpreloadedbubblesequaledthecountproducedbybeamingneutronsintothedetectorswithnothinginfrontofthem,theputativeweaponwouldbeverifiedtobeatrueone.Butifthetotalcountforthepreloadpluswarheadirradiationdidnotmatchtheno-objectcount,theinspectedweaponwouldbeexposedasaspoof.Priortothetest,theinspectorwouldrandomlyselectwhichpreloadeddetectorstousewithwhichputativewarhead,andwhichpreloadtousewithawarheadthatwas,forexample,selectedfromtheowner’sactiveinventory.Inasensitivemeasurement,suchasoneinvolvingarealnuclearwarhead,thepropositionisthatnoclassifieddatawouldbeexposedorsharedintheprocess,andnoelectroniccomponentsthatmightbevulnerabletotamperingorsnoopingwouldbeused.Evenstatisticalnoise—orrandomvariationinneutronmeasurement—wouldconveynodata.Indeed,“Forthezero-knowledgepropertytobeconserved,neitherthesignalnorthenoisemaycarryinformation,”theauthorswrite.Anecessaryfuturestepistoassessthispropositionfully,andtodevelopandreviewaconceptofoperationsindetailtodetermineactualviabilityandinformationsensitivity.Importantquestionsyettoberesolvedincludethedetailsofobtainingandconfirmingatargetwarheadduringthezero-knowledgemeasurement;specificsofestablishingandmaintainingthepre-loadeddetectorsinawaythatensuresinspectingpartyconfidencewithoutrevealinganydataconsideredsensitivebytheinspectedparty;andfeasibilityquestionsassociatedwithsafelydeployingactiveinterrogationmeasurementtechniquesonactualnuclearwarheadsinsensitivephysicalenvironments,inawaythatprovidesconfidencetoboththeinspectedandinspectingparties.Glaser,GoldstonandBoazBarak,aprofessorofcomputerscienceatHarvardUniversityandformerPrincetonassociateprofessor,firstlaunchedtheconceptforazero-knowledgeprotocolforwarheadverificationinthe2014paperinNaturemagazine.ThatpaperledForeignPolicymagazinetonametheauthorsamongits“100LeadingGlobalThinkersof2014,”andpromptedotherresearchcenterstoembarkonsimilarprojects.“Wearehappytoseethisimportantfieldofresearchgainnewmomentumandcreatenewopportunitiesforcollaborationbetweennationallaboratoriesanduniversities,”Glasersaid.SeedmoneyfortheoriginalworkcametoPrincetonfromTheSimonsFoundationofVancouver,Canada,throughanonprofitcalledGlobalZero,andfromtheU.S.DepartmentofStateVerificationAssetsFund.Clickheretoseevideo
PPPL,onPrincetonUniversity'sForrestalCampusinPlainsboro,N.J.,isdevotedtocreatingnewknowledgeaboutthephysicsofplasmas—ultra-hot,chargedgases—andtodevelopingpracticalsolutionsforthecreationoffusionenergy.ResultsofPPPLresearchhaverangedfromaportablenuclearmaterialsdetectorforanti-terroristusetouniversallyemployedcomputercodesforanalyzingandpredictingtheoutcomeoffusionexperiments.TheLaboratoryismanagedbyPrincetonUniversityfortheU.S.DepartmentofEnergy’sOfficeofScience,whichisthelargestsinglesupporterofbasicresearchinthephysicalsciencesintheUnitedStates,andisworkingtoaddresssomeofthemostpressingchallengesofourtime.Formoreinformation,pleasevisitscience.energy.gov.EstablishedbyCongressin2000,NNSAisasemi-autonomousagencywithintheU.S.DepartmentofEnergyresponsibleforenhancingnationalsecuritythroughthemilitaryapplicationofnuclearscience.NNSAmaintainsandenhancesthesafety,security,andeffectivenessoftheU.S.nuclearweaponsstockpilewithoutnuclearexplosivetesting;workstoreduceglobaldangerfromweaponsofmassdestruction;providestheU.S.Navywithsafeandeffectivenuclearpropulsion;andrespondstonuclearandradiologicalemergenciesintheU.S.andabroad.Visitnnsa.energy.govformoreinformation.Gallery:
Gallery1SetupoftheexperimentinaPPPLlaboratory(credit:ElleStarkman)
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