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Vol.14,No.11©2003JournalofSoftware1000-9825/2003/14(11)1936*+(,100080)(,100080)TTPRolesinElectronicCommerceProtocolsQINGSi-Han(EngineeringResearchCenterforInformationSecurityTechnology,TheChineseAcademyofSciences,Beijing100080,China)(StateKeyLaboratoryofInformationSecurity,InstituteofSoftware,TheChineseAcademyofSciences,Beijing100080,China)+Correspondingauthor:Phn:86-10-62635150,Fax:86-10-62635150,E-mail:qsihan@yahoo.com;Accepted2003-06-30QingSH.TTProlesinelectroniccommerceprotocols.JournalofSoftware,2003,14(11):1936~1943.:TTP(trustedthirdparty)playsanimportantroleinelectroniccommerceprotocols.DifferentrolesofTTPininlineTTPprotocols,onlineTTPprotocolsandofflineTTPprotocolsarepointedoutthroughthreeprotocolsofdifferenttypes,i.e.,Coffey-Saidhaprotocol,CMP1protocolandAsoken-Shoup-Waidnerprotocol.Theaboveprotocolsareanalyzedthoroughly,andtheircharacteristics,defectsandapproachestofurtherimprovementarediscussedrespectivelyinthispaper.Keywords:TTP(trustedthirdparty);electroniccommerceprotocol;non-repudiation;accountability;fairness:,TTP(trustedthirdparty).3,Coffey-SaidhaCMP1Asoken-Shoup-Waidner,TTPinlineTTPonlineTTPofflineTTP.,.:;;;;:TP309:AInternet,.,.,..[1~3],.,,:(1);(2);(3)*SupportedbytheNationalNaturalScienceFoundationofChinaunderGrantNo.60083007();theNationalGrandFundamentalResearch973ProgramofChinaunderGrantNo.G1999035810((973)):(1939),,,,,.:1937;(4);(5),.,:,,.,.,.“”?.,:(1);(2)TTP(trustedthirdparty),TTP.,TTP(deliveryauthority).TTP,TTP.(accountability),.[4].EOO(evidence-of-origin),.EOR(evidence-of-receipt),.BAN[5]BAN,,.,.,Kailar[6],.KailarBAN,,.[7],Kailar:(1);(2),;(3).[8]Kailar,.Kailar,3:(1);(2),;(3),.(fairness).:,,EOREOO.,,,.,,EOOEOR.:(1)(gradualexchangeprotocol).,,.,“”.:1,;2,.(2),,,,.,,.,,.,.,.,TTP,inlineTTPonlineTTPofflineTTP3.inlineTTP,TTP.,TTP.,TTP.onlineTTP,,TTP;offlineTTP,,TTP.,TTPinlineTTP,offlineTTP,TTP.,,TTP:(1)“(certificationauthority)”.,.1938JournalofSoftware2003,14(11) (2)“(notary)”.,.(3)“(deliveryauthority)”.,TTP.(4)“(adjudicator)”...,.(5)“(time-stampingauthority)”..:(m,n):mn;fX:,,.,fEOOEOO,EOO;Ka:A,A.1-aKKaA;h(m):m.,,TTP.inlineTTP,(,).:1},,,{-=aKEOOmBTTPfEOO,1},,,{-=ttpKEODmBAfEOD.(1)EOOmBTTPfTTPAEOO,,,,:→.(2)EOOmBTTPfBTTPEOO,,,,:→.(3)EODBAfATTPEOD,,,:→.,TTP,AB,AEOD(evidence-of-delivery).,EODEOR.3,TTP,3.1InlineTTPCoffey-Saidha1.1Coffey-SaidhaCoffey-Saidha[9]1996,ABm,,AEORBmEOO.Coffey-Saidha,:t1,t2:;Na,Nb:;TSA:TTP;NRS:TTP;11},,},,,{{1--=tsaaKKEOOtTSAmBAfEOO:m;11},,)}(,,,{{2--=tsabKKEORtTSAEOOhABfEOR:m;1},,,{_-=aKEOOmBAfEOOP:m;)(,,,_EOOhABfEORPEOR=:m;1)}(,,,{__-=bKEOREOOhABfEORPS:m.Coffey-Saidha,1.(1)tsaKEOOPTSAA}_{:→.:1939(2)aKEOOATSA}{:→.(3)REQNRSA:→.(4)aKaNANRS}{:→.(5)nrsaKKaEORPEOONNRSA}}_,,{{:1-→.(6)bnrsKKbEORPNBNRS}}_,{{:1-→.(7).}__{:tsaKEORPSTSAB→(8)bKEORBTSA}{:→.(9)nrsbKKbEORNNRSB}},{{:1-→.(10)bKEOOBNRS}{:→.(11)aKEORANRS}{:→.1,AP_EOO,TSATSA.Coffey-Saidha,3,.,.2,TSAP_EOO,EOO,A.3,ANRSREQ,B.4,NRSNa,A.5,A(Na,EOO,P_EOR)NRS.6,NRSNaEOO,Nb.NRS(Nb,P_EOR),B.7,BP_EOR,TSA.8,TSAS_P_EOR,EOR,B.9,B(Nb,EOR)NRS.NRSNbEOR,1011BAEOOEOR.2.2TTPCoffey-SaidhaCoffey-Saidha,TTP,TTPTSA,TTPNRS.TSA.,,.4TSA,1278.,TSA,EOOEOR.,ABTSATSAm,TSAm,n(m,TSA,),nAB.,TTP.X.509,.,.,,.,,.,.,.,,.,,TTP,.NRSTTP,.Coffey-SaidhainlineTTP,TTP,TTP.,BEOO,AEOR.Coffey-Saidha.,.,BEOOAm.AEORBm.,Coffey-Saidha.,1011.,BEOOAEOR;AEORBEOO.,Coffey-Saidha.,,mTTP,,Coffey-SaidhaAB.Coffey-Saidha:,.,3,.,AB,TTP,.,,.,.965438721TSANRSAB1110TTP’sserviceastime-stampingauthorityFig.1Coffey-Saidhaprotocol1Coffey-SaidhaOrdinaryTTP’sservice1940JournalofSoftware2003,14(11) ,NaNbEOOEOR,.,EOOEOR.EOOEORm.,.,;EOOEOR.2OnlineTTPCMP12.1CMP11995,Deng[10]CMP1CMP2.,CMP1,CMP2.CMP1:1},,,{-=aKmTTPBAEOO,1)}(,,,{-=bKmhTTPBAEOR,1},,{-=ttpKEORmBEOD.(1)kKEOOkmhTTPBABAttp}{,}{),(,,,:→.(2)kKEOOkEORTTPBttp}{,}{,:→.(3)1}{:-→ttpkEOOBTTP.(4)EODATTP:→.1,AmEOO;k,kEOO;mh(m);TTPk;(1)B.2,Bh(m)EOR,(2)TTP.TTP(2),EOO,A.,TTPEORB.,TTPEOOmh(m),EORh(m).,TTP34BA(3)(4).2.2TTPCMP1CMP1onlineTTP,CMP1inlineTTP,5,2.1,ATTPmEOO.2,TTPBm.3,BTTPEOR.TTP,45BA(m,EOO)EOD.,4.,A(m,EOO),BEOR.TTP,(m,EOO)EOD,:A,B.,onlineTTPCMP1.,BEOO,AEOREOD.CMP1.,.,BEOOAm.AEORBh(m);EODTTPBm.,ABm.,CMP1.,,34.,BEOOA(EOR,EOD);A(EOR,EOD)BEOO.,CMP1.,TTP.,TTPh(m)m,CMP1:A,Bh(m)Bm.,,3,TTPEOO,EOO54321Fig.2InlineTTPCMP1protocol2InlineTTPCMP1TTPBA:1941m.,CMP13(3)EOOBTTP:→.,1,B{EOO}k.,3,Bk,BkEOO.,CMP13(3)kBTTP:→.,CMP1.,mTTP,,CMP1.,h(m),m.,,h(m,k)h(m).CMP1,,m,TTP.3OfflineTTPAsokan-Shoup-Waidner3.1Asokan-Shoup-Waidner1998,AsokanofflineTTP[11],.Asokan-Shoup-Waidner4:exchange,abort,resolve_Aresolve_B.,exchange.AB,.exchange,NaNbAB;mAB;ttpKbaaKKNmC},,,{=.(1):BA→1)}(,,,,{),(,,,,1-=aKbabamhCTTPKKmhCTTPKKme.IFBgivesupTHENquitELSE(2):AB→1)}(,1{),(2-=bKbbNhmeNhme.IFAgivesupTHENabortELSE(3):BA→aNmme,3=.IFBgivesupTHENresolve_BELSE(4):AB→bNme=4.IFAgivesupTHENresolve_Aabort:(1):TTPA→1}1,{,1,1-=aKmeabortedmeabortedma.IFBhasresolvedTHENresolve_AELSE(2):ATTP→1}1,{,1,_-=ttpKmaabortedmaabortedtokenabort.resolve_B:(1):TTPB→bbNmemeKmrb,2,1,1=IFabortedTHEN(2):BTTP→tokenabort