Study on Trust Evolution and Simulation Oriented to Cloud Services

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1 Joral of Advaced Maagemet Scece Vol., No., Je 014 Stdy o Trst Evolto ad Smlato Oreted to Clod Servces Zho Ye School of Maagemet ad Egeerg, Nag Uversty, Nag, Cha yzho@.ed.c I ths paper, trst stdy s focsed as a research drecto of clod secrty. The artcle frst examed the related researches ot trst the codto of clod servces. Ad the the paper provded a model of the trst evolto based o the theory of the lfe cycle. After that the paper descrbed the smlato reslts wth the model o the Netlogo platform. Fally the artcle dscssed the cotrbtos ad mplcatos of the research as well as the ftre stdy wor. Abstract Clod comptg, as a ovel bsess model, has bee pad more ad more atteto from academa ad dstry. The secrty sse of clod comptg s a ey costrat for ts applcatos. Some scholars stded the secrty sses of clod comptg from the vewpot of trst. However, the past researches of trst maly focsed o the comptato of trst degrees ad overlooed the research of evolto of trst relatoshps. I addto, these research models cold ot completely adopt the evromet of clod comptg. Ths artcle costrcted a trst evolto model based o the trade evalato mtally combed wth the theory of terpersoal socety trst relatoshp ad characterstcs of clod servces. Smlato was made o the Netlogo platform ad the smlato reslts proved the model s relle ad effectve. The model has a certa appled vale. II. A. Defto of Trst Trst s a complex cocept for whch there s o versally accepted scholarly defto at preset. There are a great mber of papers that stded trst deftos from dfferet vews sch as a psychologcal state [5]; a behavor [6]; a atttde [7]; a cofdece [8]; a expectacy [9] ad [10]; a belef or set of belefs [11]; a dspostoal varle [9]; a statoal varle[1]; a strctral varle [13]: a socal agecy relatoshp varle [14]; a terpersoal varle [15]; a orgazatoal relatoshp [16]; a cooperato [17]; ad rellty, faress, ad goodwll/beevolece [18]. Aother compoet of trst s reptato. Reptato s perhaps a compay s most valle asset [19]. Trst s sbectve whle reptato s obectve. Both reflect the dfferet aspects of trst. I ths paper we defe trst as a relatoshp betwee the ser ettes ad servce provder ettes der the evromet of clod servces. Trst maes the ser ettes are wllgess to try sg the servces ad resorces provded by the servce provder ettes ad to tae a certa rs. Idex Terms clod comptg, clod servce, trst, evolto, smlato, the behavor smlarty theory I. INTRODUCTION Clod comptg s a ovel bsess model that eles bqtos, coveet, o-demad etwor access to a shared pool of cofgrle comptg resorces (e.g., etwors, servers, storage, applcatos, ad servces) that ca be rapdly provsoed ad released wth mmal maagemet effort or servce provder teracto [1]. Its essetal characterstcs clde odemad self-servce, broad etwor access, resorce poolg, rapd elastcty, ad measred servce. Clod servces are a fdametal compoet clod comptg: frastrctre, platforms, ad software are provded ad cosmed as o demad servces. I the recet years, clod comptg has grow from beg a promsg bsess cocept to oe of the fast growg segmets of the IT dstry. Bt as more ad more formato o dvdals ad compaes are placed the clod, cocers are begg to grow ot st how safe a evromet t s [3]. So clod secrty s reglarly cted as a hbtor for the more rapd adopto of clod servces [4]. Clod secrty volves may aspects cldg access cotrol, detty maagemet, motorg, ecrypto, data, prvacy protecto, frastrctre, ad trst. Amog them, trst s oe of the core sses of clod secrty. B. Related Theores ot Trst Formg Mechasm Socal Exchage Theory (SET) Socal exchage volves the voltary actos of dvdals, whch are motvated by the expectato that ftre retrs receved from others wll be mch larger tha crret costs pt. SET explored by Bla [0], therefore, s to expla the pheomea throgh statg the formato of socal cotracts betwee two or more partes, where preset socal costs are vested exchage for ftre, o-garateed socal rewards. People form relatoshps o the bass of trst, especally drg tal exchages accordg to the SET. It s eve the trth o the Iteret, where cstomers Mascrpt receved September 1, 013; revsed November 7, Egeerg ad Techology Pblshg do: /oams LITERATURE REVIEW 88

2 Joral of Advaced Maagemet Scece Vol., No., Je 014 typcally perceve hgher rss compared to covetoal shoppg evromet as a reslt of log dstaces, vrtal dettes, or lac of reglatos [1]. Expectato-Cofrmato Theory (ECT) ECT s proposed by Olver [] to wdely stdy cosmer satsfacto, reprchase teto ad behavor. The derlyg logc of the ECT framewor s: cosmers frstly form a tal expectato pror to prchase, ad the egeder perceptos ot ts performace after a perod of tal cosmpto. Ths, they may decde the satsfacto level based o the extet to whch ther expectato s cofrmed throgh assessg the perceved performace vs-à-vs ther orgal expectato. Fally, the satsfed cosmers form reprchasg tetos. Theory of Reasoed Acto (TRA) TRA orgated by Fshbe ad Aze [3] s to aalyze the correlato of belef, atttde, teto ad behavor. The TRA maly asserts that belefs affect the perso s atttdes, that s, ther favorle or favorle evalatos of the others; ad atttdes tr flece behavoral teto, whch s a good predctor of actal behavor. I addto, t also spports that the sbectve orm cocerg the behavor that s the totalty of ormatve pressres comg from the referets who th the perso shold or shold ot perform the behavor s a dspesle alteratve atecedeces of behavoral teto. The ormatve orm, or ormatve pressre s maly derved from exteral evromet. The ove theores are helpfl to derstad trst formato. It s also a theoretcal base of or model costrcto. C. Stdy of Trst Maagemet Based o the defto of trst ths paper we focs o the trst stdy betwee ettes der the codto of clod servces. I order to solve the trst problem amog strage ettes Blaze et al provded the cocept of trst maagemet [4]. The trst maagemet s also called the access cotrol based o competece [5]. It cold ot estlsh a dyamc trst relatoshp wth strage ettes becase t reqres ssg a credetal for sers advace by provders. L et al provded a smple rolebased trst maagemet [6]. It combed wth the rolebased access cotrol to the trst maagemet. At preset, the trst maagemet systems represeted by roles descrbe ad deal wth trst relatoshps betwee ettes a accrate ad ratoal way. It s overrgoros ad dffclt to descrbe the extet of the trst relatoshp betwee ettes. It s ecessary to mae t flexble for the balace betwee secrty ad coveet access ad dvdato. Beth et al [7] preseted a method for the valato of trstworthess whch ca measre the extet of trst a relatve way from the stadpot of the sbectve trst ad o-ratoal. Ths model of the valato of trstworthess maes se of the recommedato of smlarty ettes ad themselves expereces to atomatcally compte the trst degree wth the mathematcal models. The comptg reslts are sed to mae the athorty decso. Ths trst egotato mechasm ca be sed as a applcato base the evromet of clod servces. I smmary, the ove researches ot trst maagemet provde a sbstatal bass for trst measremet ad cotrol. Ths paper wll exted the preset research achevemets to stdy the trst evolto process ad treds based o the trst degree calclato. III. A TRUST EVOLUTION MODEL CONSTRUCTION A. A Trst Evolto Model Dscrpto There ca be dfferg phases a trst relatoshp process sch as bldg trst, a stle trst relatoshp ad declg trst. Trst ca be lost qcly: as Nelse states [8]: It [trst] s hard to bld ad easy to lose: a sgle volato of trst ca destroy years of slowly accmlated credblty. Drg bldg p trst stage, sers provde servce reqests ad access caddates (clod servce provders) throgh comptg trst degrees. The caddate s selected ad added to the lst of the relle clod servce provders whe the trst vale s more tha the threshold that the ser had set p advace. I the same tme, clod servce provders also access sers wth the same way. As log as the ser ad the provder all satsfed a trst relatoshp has bee estlshed. That meas they have a trade relatoshp. After that the trst eters a developmet stage. Drg ths stage the ser ad the provder cote to access f ther trst degrees are more tha ther settg the thresholds servce qalty, se behavor, ad the degrees of satsfacto after every deal. If satsfacto the trst relatoshp matas ad cotes to trade, otherwse trst decles ad eters demse as show Fg. 1. B. Trst Degree Comptato The ey sse s to calclate the trst degree the trst evolto model. Trst degree comptato cldes drect trst degree whe the ser ad the provder have trades ad drect trst degree whe the ser ad the provder have o trade. Drect trst degree s calclated terms of the degree of trade satsfacto alog wth the tradg volme ad the tme horzo. TD C( ). (1) SD 1 where TD s the drect trst vale ad SD s the vale of the degree of trade satsfacto. Amog (1) C( ) A( ) M ( ) 1 t t t 0 t 0 D 1 D m 1 m. () Idrect trst degree s compted based o the method of the ser behavor smlarty (UBS). I the sparse data codto the sparse ser formato reslts correct comptg otcomes wth the tradtoal smlarty algorthms (Pearso correlato coeffcet). UBS method ca effectvely solve ths problem. 014 Egeerg ad Techology Pblshg 89

3 Joral of Advaced Maagemet Scece Vol., No., Je 014 Sppose the clod trade etty a ad the target etty b have trades. A depedet evalato set s represeted by { v 1,v,,v } after th trade ad meas the mber of evalatg dcators ( ths research =4). The behavor featre vector of th trade evalato s preseted by L v, v,, v ), 1 ( 1 (3) The total behavor smlarty vector ca be measred wth () ad (3) U (,, 1, ), 1 C( ) v, 1,. (4) 1 Trst Degree Users Ital Trst Formato Trst Developmet Trst Demse Y threshold N Trade Termato Provde Reqests Pblsh Servces Gve p Provders N Evalato of trstworthess threshold Y Lst of Relle Provders Servce Qalty Evalato Update Trst Degree Trade Relatoshp Estlshmet Provders Selecto Use Behavor Evalato Trst Threshold Evalated Trst Degree Crve Tme & Trade Nmbers Fgre 1. A trst evolto model. Sppose S XY s the behavor smlarty of the trade etty X ad Y to the target etty Z. S XY 1 X Y 1. (5) X 1 Whe 0 or 0 defe S 0. 1 X 1 There are two statos to calclate UBS der the codto of clod servces. The trade etty a ad the target etty b had trades happeed. Defe r s the left trade ettes except a. Y Y XY U a b ( 1 r) s the total behavor smlarty vector. The behavor smlarty of a ad a ca be calclated based o (4), (5) Saa 1 a a 1. (6) a 1 The trade etty a ad the target etty b had o trade record. a I ths stato U cold ot be compted. We mst select a referece etty whose reptato vale (RV) s the greatest amog the same ettes. Sppose a s l a referece etty, we defe RVa l max RVA. Here A meas a class of all the same ettes except a. I ths way we have S aa RV al S ala RV al 1 1 ( al al a 1 ) a. (7) Combed wth (1) ad (7) the drect trst degree ca be calclated by TI S 1 r aa TD Fally we ca get a total trst degree TC 1 TD. (8) TI. (9) where 1 1, 1, they represet drect trst degree ad drect trst degree weghts respectvely. C. The Best Servce Provder Selecto Algorthm 014 Egeerg ad Techology Pblshg 90

4 Joral of Advaced Maagemet Scece Vol., No., Je 014 Whe a lst of the relle clod servce provders s got the best provder shold be chose. We desg a algorthm based o the rle of TOPSIS (Techqe for Order Preferece by Smlarty to Ideal Solto) [9] wth the servce capacty dcators. A tal evalato matrx s costrcted Tle I. TABLE I. TCS A AN INITIAL EVALUATION MATRIX a 1 a a 3 a 4 tcs1 A11 A1 A13 A14 tcs m Am1 Am Am3 Am4 A lst of the relle clod servce provders ca be represeted by a vector TCS={tcs 1,tcs,,tcs m }, m meas the legth of the vector. The evalato dcators s represeted by A={a 1,a,a 3,a 4 }, they represet rellty, badwdth, cost, ad performace respectvely [30]-[3]. Costrctg the decso matrx wth the etropyweght method Sppose the decso matrx R ( r ) s ormal. We m4 have r a m 1 a, (1 m,. (10) 1 4) amog them A ( a ) actg as the tal decso m4 matrx. Comptg etropy e m e r l r, ( 1/ l m, e 0). (11) 1 Comptg the dverget coeffcet g Comptg weghts w g 1. (1) e g w. (13) 4 1 Costrctg the decso matrx X ( x ) m4 x w r, (1 m, 1 4).(14) Calclatg the deal solto ad the egatve deal solto The best vale ad the worst vale the decso matrx are sed to costrct the deal solto ad the egatve deal solto. x max x, x m x, (1 m, 1 4) (15) Comptg the dstace measre The dstace measre represets the adacet extet betwee the deal solto ad the relle provder solto. It ca be calclated by the Ecld dstace. g d 4 1 ( x x ), d 4 1 ( x x ), (1 m, 1 4) (16) Calclatg the relatve dstace measre Sppose the relatve dstace measre C represet the dstace betwee the caddate solto ad the deal solto. We have C d /( d d ), (1 m) (17) Sortg the relatve dstace measres Sort the relatve dstace measres C. The bggest vale represets the best provder amog them. D. Satsfacto Degree Comptato Satsfacto degree comptato cldes both the ser to the provder ad vce versa. The satsfacto degree of the ser to the provder s calclated by the for evalato dcators. 4 SD w a, w 1. (18) s where w s the weght of the a dcator. The satsfacto degree of the provder to the ser s calclated by the ser se behavor evalato dcators as show Tle II. TABLE II. THE USE BEHAVIOR EVALUATION INDICATORS Idcators Stadard Vales b 1: Operato Normalzato Volatg Rle 0~5 Tmes b : Cotract Complace Gradg 0~5 b 3: Paymet O Tme Gradg 0~5 SD 3 b, (0 b 5, 1,,3) s (19) 1 E. Dyamc Update of Trst Degree ad Reptato Degree Trst degree ad reptato degree are dyamc chage wth the trade crease the evromet of clod servces. We adopt a cremet pdate method. Whe satsfacto degree SD s less tha the set threshold ST, a pshmet fcto P s added to calclate the cremet of trst degree ΔTV. TV [( SD ST)/ SDmax ] TV ( m/ mav) P (0) where TV s the trst degree, m s the trade volme, ad m av s the average vale of all the trade volmes. h P f [1/( l e )] (1) where f=0 f the trade s sccessfl; f=1 otherwse. h 1/( l e ) s the acceleratg factor; h s the amot of the trade falres ad l s the mber related the trade volme. The trst degree pdate formla s TV 1 TV TV 1,,, () Smlarly the reptato degree pdate formla s 014 Egeerg ad Techology Pblshg 91

5 Joral of Advaced Maagemet Scece Vol., No., Je 014 RV 1 RV RV 1,,, (3) IV. SIMULATION RESULTS AND ANALYSIS A. Idcators ad Parameters Selecto We set p three dcators to measre the trst evolto based o the related researches [33]. Proposto 1 A average trst desty of the trst system eqals to where Node e 1 RV / (4) Node, meas the trade mber of tmes. represets the trst level of the system. Proposto A collorato sccess rato eqals to S / 100% (5) where S s the mber of the trade sccess. reflects the rellty of the trst evolto model. Proposto 3 A average trst vale TV of the clod servce provder eqals to TV TV / N (6) TV R where the ser class s N CU 1 N CU (N s the mber of the sers), the clod servce provder set s NCS CS 1 M (M s the mber of the provders), the trst relatoshp set s R {( CS, CU, TV ) CU NCU, CS NCS}. TV reflects the varato tred of the trst relatoshp of the provder. Before smlato the tal parameters had bee set p as show Tle IV after may trals. TABLE IV. THE INITIAL PARAMETERS Parameters Assgmet Parameters Assgmet M N Trst thr. Satsfacto thr. Rato of balefl odes %, 0%, 30%, 40% Wgt. of rellty Wgt. of badwdth Wgt. of cost Wgt. of performace No. of trades pro. = provders; thr. = threshold; wgt.=weght where the rato of balefl odes meas the rato of CU B all the sers. The smlato reslts are show Fg. to Fg. 9. Fgre. chage tred 10% balefl odes TABLE III. THE CLASSIFICATION OF THE PROVIDERS AND USERS Ettes CS 1 CS CS 3 CS 4 CU A CU B Servce promse/ assgmet hgh/hgh tal trst degree hgh/hgh tal trst degree low/low tal trst degree low/low tal trst degree Hgh qalty Low qalty Promse performg/ assgmet good/hgh evalato vale poor/low evalato vale good/hgh evalato vale poor/low evalato vale Before smlato t s ecessary to classfy the provders ad sers (to see Tle III). B. Smlato Reslts Two ds of smlato were carred ot ths stdy o the Netlogo platform based o the prcple of the mlt-aget smlato. Oe s to verfy the rellty of the trst evolto model. The other s to explore the trst evolto developmet treds wth the model. The ettes of provders ad sers are represeted by agets. The trade betwee agets s smlated by the teracto of agets. Fgre 3. Fgre 4. chage tred 0% balefl odes chage tred 30% balefl odes 014 Egeerg ad Techology Pblshg 9

6 Joral of Advaced Maagemet Scece Vol., No., Je 014 Fgre 9. Fgre 5. chage tred 40% balefl odes chage tred 40% balefl odes chage tred 10% balefl odes Fgre 10. TV chage tred 10% balefl odes Fgre 6. Fgre 7. chage tred 0% balefl odes Fgre 11. TV chage tred 0% balefl odes Fgre 8. Fgre 1. TV chage tred 30% balefl odes chage tred 30% balefl odes 014 Egeerg ad Techology Pblshg 93

7 Joral of Advaced Maagemet Scece Vol., No., Je 014 I order to explore the evolto treds of trst for ds of provders were set p (to see Tle III) to codct for tmes of smlato wth the for dfferet balefl odes respectvely. The smlato reslts are show Fg. 10 to Fg. 13. Fgre 13. TV chage tred 40% balefl odes C. Smlato Reslts Aalyss We fod that the average trst desty s more tha 80% whe the rato of balefl odes s less tha 0% from the Fg. ad Fg. 3. Ths reslt proved that the smlato model we desged s more relle tha other dyamc trst models. Wth the crease of the rato of the balefl odes has the lower vale from the start (to see Fg. 4 ad Fg. 5). However wth the crease of trade mber of tmes goes p gradally ad eeps stle fally. It also dcates or model s very relle. has the same chage treds o matter the ratos of balefl odes are dfferet or ot. It s becase a pshmet fcto P s added or trst model to esre a hgh trade sccessfl rato whe the worst sers are elmated. For expermets have bee doe wth the for dfferet ratos of balefl odes (that meas CU B rato), 10%, 0%, 30%, ad 40% respectvely from Fg. 10 to Fg. 13. The CS 1 ad CS have the same tal trst degrees bt the developmet treds are dramatcally dfferet wth the crease of the trade mber of tmes. The trst degree of CS goes dow qcly to a lower level bt the trst degree of CS 1 goes p to a hgher level becase of the dfferet promse performg. Althogh CS 3 has the lower tal trst degree ts average trst vale goes p stly becase of good promse performg. Dstctly, the average trst vale of CS 4 goes dow gradally becase of ts low tal trst degree ad poor promse performg. V. CONCLUSIONS AND DISCUSSIONS A. Coclsos The paper descrbes a mtal assessmet trst evolto model based o the theory of terpersoal socety trst relatoshp ad clod servce characterstcs. The model has bee verfed by smlato. Smlato reslts proved that the model s relle ad effectve. It provdes a ovel referece model for solvg clod servce secrty sse. The ma cotrbtos of the paper clde pttg forward the cocept of the mtal assessmet betwee trstors ad trstees der the codto of clod servces; costrctg a dyamc evolto model wth the crease of the trade mber of tmes based o the characterstcs of clod servces; desgg a set of algorthms to measre the trst degree ad the reptato degree terms of the theory of terpersoal socety trst relatoshp ad the theory of the behavor smlarty; verfyg the rellty ad correctess of the model ad algorthms throgh smlatos; the smlato reslts ca be sed to specfy the behavor of the provders ad sers to mata a loger trst relatoshp. B. Dscssos The model ad the smlato reslts dcate: the trst relatoshp s mtal. Both clod servces provders ad sers behavor all flece the varato of the trst vales; order to mata a hgher trst degree both sdes of the clod servces mst preset good behavor; a pshmet mst be gve whe the trade s falre. I addto the trade tme ad volme also mst be cosdered. The ftre stdy wll focs o two aspects. Oe s to revse ad exted the model tself to mae t adapt to more geeral statos. The other s expermet desg ad parameters selecto, sch as the pshg fcto desg, the assgmet of the tal trst degree, ad so o mst be cosdered careflly ad expermetally. REFERENCES [1] P. Mell ad T. Grace, The NIST Defto of Clod Comptg, NIST Specal Pblcato , Natoal Isttte of Stadards ad Techology (NIST), September, 011. [] C. Ba, M. Kze, J. Nms, ad S. Ta, Clod Comptg: Web- Based, Dyamc IT Servces, Hedelberg, Germay: Sprger, 011, ch. 1, pp. 1. [3] S. Sbash ad V. Kavtha, A srvey o secrty sses servce delvery models of clod comptg, Joral of Networ ad Compter Applcatos, vol. 34, o. 1, pp. 1 11, 011. [4] P. G. Dorey ad A. Lete, Commetary: Clod comptg - A secrty problem or solto? Iformato Secrty Techcal Report, vol. 16, pp , Ag-Nov 011. [5] D. Rossea, S. St, R. Brt, ad C. Camerer, Not so dfferet after all: A cross-dscple vew of trst, Academy of Maagemet Revew, vol. 3, o. 3, pp , [6] D. E. Zad, Trst ad maageral problem solvg, Admstratve Scece Qarterly, vol. 17, o., pp. 9-39, 197. [7] D. L. Kega ad A. H. Rbeste, Trst, effectveess, ad orgazatoal developmet: A feld stdy R&D, Joral of Appled Behavoral Scece, vol. 9, o. 4, pp , [8] A. K. Cohe, Devace ad Cotrol, Eglewood Clffs, NJ: Pretce-Hall, 1966, ch. 1, pp. 3. [9] J. B. Rotter, Iterpersoal trst, trstworthess, ad gllblty, Amerca Psychologst, vol. 35, o. 1, pp. 1-7, [10] J. Scazo, Socal exchage ad behavoral terdepedece, Socal Exchage Developg Relatoshps, R. L. Brgess & T. L. Hsto Ed., New Yor: Academc Press, 1979, pp [11] B. Barber, The Logc ad Lmts of Trst, New Brswc, NJ: Rtgers Uversty Press, 1983, ch. 1, pp.. [1] C. Johso-George ad W. C. Swap, Measremet of specfc terpersoal trst: Costrcto ad valdato of a scale to assess trst a specfc other, Joral of Persoalty ad Socal Psychology, vol. 43, o. 6, pp , Egeerg ad Techology Pblshg 94

8 Joral of Advaced Maagemet Scece Vol., No., Je 014 [13] J. D. Lews ad A. J. Wegert, Trst as a socal realty, Socal Forces, vol. 63, o. 4, pp , [14] S. P. Shapro, The socal cotrol of mpersoal trst, Amerca Joral of Socology, vol. 93, o. 3, pp , [15] J. K. Rempel, J. G. Holmes, ad M. P. Zaa, Trst close relatoshps, Joral of Persoalty ad Socal Psychology, vol. 49, o. 1, pp , [16] R. Mayer, J. Davs, ad F. D. Schoorma, A tegratve model of orgazatoal trst, Academy of Maagemet Revew. vol. 0, o. 3, pp , [17] D. Gambetta, Ca we trst? Trst: Mag ad Breag Cooperatve Relatos, D. Gambetta Ed. electroc edto, Departmet of Socology, Uversty of Oxford, 000, ch. 13, pp [18] J. H. Dyer ad W. Ch, The role of trstworthess redcg trasacto costs ad mprovg performace: Emprcal evdece from the Uted States, Japa, ad Korea, Orgazato Scece, vol. 14, o. 3, pp , 003. [19] H. Nssebam, Ca trst be secred ole? A theoretcal perspectve, Etcae Poltca, o., Dec [0] P. Bla, Exchage ad Power Socal Lfe, Wley, New Yor, 1964, ch. 1, pp. 4. [1] R. L. Olver, A cogtve model of the atecedets ad coseqeces of satsfacto decsos, Joral of Maretg Research, vol. 17, o. 4, pp , November [] S. J. Ta, Strateges for redcg cstomer s rs averso ad teret shoppg, Joral of Cosmer Maretg, vol. 16, o., pp , [3] M. Fshbe ad I. Aze, Belef, Atttde, Iteto ad Behavor: A Itrodcto to Theory ad Research, Readg, MA: Addso- Wesley, 1975, ch. 1, pp. 5. [4] M. Blaze, J. Fegebam, ad J. Lacy, Decetralzed trst maagemet, Proc. IEEE Symp. o Secrty ad Prvacy, Washgto, IEEE Compter Socety Press, 1996, pp [5] W. H. Wsborogh, K. E. Seamos, ad V. E. Joes, Atomated trst egotato, Proc. DARPA Iformato Srvvlty Cof. ad Exposto, S. C. Hlto Ed. New Yor: IEEE Press, 000, pp [6] N. H. L, W. H. Wsborogh, ad J. C. Mtchell, Dstrbted credetal cha dscovery trst maagemet, Joral of Compter Secrty, vol. 1, o. 11, pp , 003. [7] T. Beth, M. Borcherdg, ad B. Kle, Valato of trst ope etwors, Proc. 3rd Eropea Symposm o Research Compter Secrty, Lodo, UK: Sprger-Verlag, 1994, pp [8] J. Nelse. (1999). Trst or bst: Commcatg trstworthess web desg, Jacob Nelse s Alertbox. [Ole]. Avalle: [9] D. L. Olso Comparso of weghts TOPSIS models, Mathematcal ad Compter Modelg, vol. 40, pp , October 004. [30] J. Hassa, L. X. Hg, U. Kalm, A. Asad, S. Y. Lee, ad Y. K. Lee, A trst model for bqtos systems based o vectors of trst vales, Proc. 7th IEEE It l Smp o Mltmeda, Washgto: IEEE Compter Socety Press, 005, pp [31] R. He, J. W. N, ad G. W. Zhag. CBTM: A trst model wth certaty qatfcato ad reasog for pervasve comptg, Parallel ad Dstrbted Processg ad Applcatos, vol. 3758, pp , 005. [3] W. J. L ad L. D. Pg. Trst model to ehace secrty ad teroperlty of clod evromet, Clod Comptg, vol. 5931, pp , 009. [33] S. Marsh, Formalzg trst as a comptatoal cocept, Ph.D. dssertato, Dept. Comptg Scece ad Mathematcs, Uversty of Strlg, Scotlad, UK, Y. J. Zho s a Professor of Idstral Egeerg at the Nag Uversty, P. R. Cha. He was bor Oct Nag Cty, Jags, P. R. Cha. He got hs Ph.D. from the Cty Uversty of Hog Kog 00. He has over 8 years worg ad research experece. He codcted a post-doctoral research at Florda Atlatc Uversty, U.S.A. drg He s the athor of 5 boos ad over 70 oral ad teratoal coferece papers. Artcles pblshed the Iteratoal Joral of Mafactrg Techology Maagemet, the Iteratoal Joral of Idstral Ergoomcs, the Iteratoal Joral of Operatos ad Prodcto Maagemet, the Iteratoal Joral of Advaced Mafactrg Techology, ad so o. Hs prevos research focsed o Compter Itegrated Mafactrg. Hs preset terest research areas cldg clod servce spply cha maagemet, maagemet formato systems, ad logstcs ad spply cha maagemet. Prof. Zho s a seor member of Chese Mechacal Egeerg Socety ad a fellow of Chese Idstral Egeerg Isttto. He was awarded a secod prze ad a thrd prze of the mster s scece ad techology. 014 Egeerg ad Techology Pblshg 95