Automated Trust Negotiation Model based on Dynamic Game of Incomplete Information

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1 2668 JOURNAL OF SOFTWARE, VOL 8, NO 10, OCTOBER 2013 Automated Trust Negotiatio Model based o Dyamic Game of Icomlete Iformatio Hogwei Che, Shuig Wag, Hui Xu, Zhiwei Ye,*Chuzhi Wag School of Comuter Sciece, Hubei Uiversity of Techology, Wuha, Chia chw2001@siacom Abstract This aer rooses a automated trust egotiatio model based o dyamic game of icomlete iformatio Through the trust evaluatio o the early stage of the cosultatio rocess ad differet rocesses for trust at the later stage, this aer itroduces the thought of dyamic game ad establishes a evaluatio model based o trust relatioshi aalysis First of all, through the aalysis ad comariso, this aer combies the automatic egotiatio rocess ad the thought of game, ad discusses the trust evaluatio factors for the early stage of the egotiatio Ad the this aer quatifies the rivacy value ad the trust degree, rovides a method of establishig automated rocess for trust egotiatio based o the dyamic game, ad fially gives the examle aalysis ad discussio for this model Idex Terms Automated Trust Negotiatio, Dyamic Game, Trust Degree, Game Tree I INTRODUCTION I the oe etwork eviromet, Automated Trust Negotiatio (ATN) mechaism is suitable for rocessig requests of users ad etwork services about trust issues i differet security domais, icludig disclosure of the resective access cotrol strategy, the certificate exchage, cosultatio message assig, rivacy rotectio[1-2] Its characteristics are as follows First, the trust relatioshi betwee strager etities through the attribute certificate exchage is established Secod, both cosultative arties ca defie the access cotrol olicy, i order to regulate each other for the resource access Third, trusted third-arty articiatio is ot required I trust egotiatio based o the attribute certificate, the focus of egotiatio is to cotrol the access to a resource, ad the strategy is achieved by secific access cotrol [3-5] Geerally, there exist two eer etities i the automated trust egotiatio model, oe called server which ows resources, ad the other called cliet which requests sources Servers ad cliets are i differet trust domais, so the two egotiatio arties do t fully trust each other The sesitive iformatio or service ca be accessed util trust is established through egotiatio As for egotiatio strategy, William ut forward the ethusiastic egotiatio strategy with higher efficiecy ad the stigy egotiatio strategy for better rivacy rotectio Yu thought that, cotrollig the access to rotected resources i trust egotiatio ot oly icluded the demad resources of users for fial access, but also icluded the certificate itself [6] Boatt made use of the rimitive redicate filter to reduce access cotrol olicy ad imroved the egotiatio efficiecy Tia Liqi used the Bayesia etwork to redict user s behavior trust, ad attemted to use the game theory to build trust TrustBuilder trust system used careful egotiatio strategy ad attemted to sythesize the advatages of both ethusiastic ad stigy egotiatio strategies Trust- X egotiatio strategy used vote of cofidece ad trust memory, so that the egotiatio efficiecy was imroved [7-11] Game theory is a effective tool to aalyze the iteractio of both sides May scholars aly game theory to etwork trust ad security A L1-VPN fair resource sharig roblem as a Adative Two-Stage Bargaiig Process Scheme is formulated by game theory [12] A trust evolutio model for social etwork is established based o Logistic model ad evolutioary game theory, [13] A Game Theory-Based model which describes the relatioshi betwee security ad efficiecy is reseted, ad the existece of Nash equilibrium i this model is roved [14] I order to revet ratioal layers cheatig, the reeated iteractio method to rovide motivatio so as to attract the layers to cooerate i the recostructio hase is alied The scheme has higher safety ad effectiveess, to better meet the alicatio requiremets [15] I this aer, a automated trust egotiatio model based o dyamic game of icomlete iformatio is roosed I sectio 2, we discuss trust relatioshis, roose a automated trust egotiatio model, ad give a game model for automated trust egotiatio I sectio 3, we establish a dyamic egotiatio mechaism, icludig calculatio of trust degree evaluatio, settig of a threshold for dyamic adustmet, calculatio of certificate loss, choosig of Policy, ad rocess of dyamic game I sectio 4, we rovide maig rules betwee egotiatio sequece ad game tree, ad give stes for costructio of the game tree I sectio 5, we roose a algorithm of dyamic game for automated trust egotiatio, ad aalyze the algorithm comlexity I sectio 6, we aalyze the egotiatio rocess of dyamic game i the case of icomlete iformatio through a examle I sectio 7, we give our coclusio II TRUST RELATIONSHIPS AND GAME ANALYSIS A Characteristics of Game for Iteractio doi:104304/sw

2 JOURNAL OF SOFTWARE, VOL 8, NO 10, OCTOBER I etwork eviromet, resource betwee odes or service iteractio ofte exhibits a game behavior [16-23] Automated trust egotiatio is a dyamic game rocess of icomlete iformatio for both arties to exchage certificate or resource, select the aroriate egotiatio strategy ad be mutually authorized The basis of iteractio for both arties is mutual trust, ad the buildig of trust esures the ormal service I the iteractive rocess of gradually buildig trust betwee odes, some commo exteral behaviors ca be discovered as follows (1) Both arties of iteractio show ratioality, which reflects i two asects First, as arties of iteractio, both obtai the other arty's trust realized by certificate iteractio, ad the trust is obtaied by this kid of obective existece Secod, whe both make decisios, they ot oly take ito accout the curret iteractio, but also cosider other odes with the same the iterests for each other (2) Dyamic ad reetitive characteristics of game Iteractio betwee the two arties of the game is ofte a dyamic game of icomlete iformatio, ad each other makes trust evaluatio through some obective factors, such as iteractive history, thus dyamically adusts their strategies Reroducibility meas reeated games of certificate or resource i a iteractio ad role exchages for iteractio of odes (3) No-zero-sum characteristic of game Usually, the game betwee odes is a o-zero-sum game, which ca achieve a wi-wi situatio through the iteractio, ad is usually erformed i a successful iteractio that the resource demader ca obtai the corresodig resource, ad the resource rovider ca access each other's trust, ready for subsequet resource request iteractio Failure of the iteractio causes egative effects for subsequet iteractio due to the historical record B The Process of Trust Negotiatio This aer cosiders the trust evaluatio at the early stage of the cosultatio ad differet situatios for the trust at the later stage, divides the automated trust egotiatio rocess ito three hases, as show i Figure 1 Negotiatio arties of both Cliet ad Server eter ito the early stage of egotiatios, ad first obtai the situatio of each other's trust from resective local areas, called as the stage of obective trust evaluatio The accordig to each other's assessmet situatio, select the aroriate egotiatio strategy for cosultatio, called as the stage of dyamic egotiatio Fially, at the ed of cosultatios, both arties of egotiatios udate their cosultatio iformatio to record the history ad rovide iformatio to other odes, call as the stage of cosultatio recordig Figure 1 A Automated trust egotiatio Model C Game Model for Automated Trust Negotiatio The existig egotiatio strategy is the rocess to costruct the egotiatio tree Usually, certificates are suosed as odes, ad the rocess of ulock-certificates are suosed as sides This rocess is similar to the game with icomlete iformatio Both sides who articiate i the game ca be abstracted by decisio ode, ad the certificate set of disclosig ca be abstracted by brach The rocess of egotiatio is the rocess of costructig the game tree; via icome fuctio to calculate the articiator s fial effectiveess ad to solve the Nash equilibrium I the dyamic game of icomlete iformatio, accordig to the aalysis above, the trust egotiatio model based o dyamic game ca be abstracted ito quadrule form Γ = ( PCSU,,, ), i which P is game articiat, icludig both arties, the Server arty ad the Cliet arty, P : P = { Server, Cliet}, C is the collectio of cosultatio certificates, the oe for Server recorded as C s ad the oe for Cliet oted as C c ad their corresod rivacy values are resectively marked as ad s, c s S: S = { Ss, Sc}, S is the strategy set of c the Cliet arty, o-emty set, S s is the strategy set of the Server arty, o-emty set, ad U is loss (rofit) fuctio Sc Ss U III ESTABLISHMENT OF DYNAMIC NEGOTIATION MECHANISM A Calculatio of Trust Degree Evaluatio Before the cosultatio betwee the two arties, reliability is collected from the etwork ad history, which are ad h for hyothesis, i [0,1], i {, h} If h( ) is recorded as historical iformatio for iteractio, ad h is measured by roortio of the successful umber for iteractio ad the total umber, the

3 2670 JOURNAL OF SOFTWARE, VOL 8, NO 10, OCTOBER 2013 h = + m hl() t h() t (1) 0 k= 1 k= 1 i which 0 is the iitial value whe the two arties without iteractio history Recommedatio of etwork odes is marked as t, ( ) i which ti () is the curret trust degrees for odes, ad 0 Iteractio ti () = If is measured by No - iteractio the weighted average of the recommedatio degree, the 1 = ti () (2) i= 1 The obective trust value of both arties for cosultatio is measured by the comositio of two arts ad h = λαh + (1 λ) β (3) i which α is the atteuatio factor, β is ucertai factor for etworks α is used to measure certai effects o iteractio caused by time i the iteractio rocess, ad β is used to measure the ucertai factors i the etworks B Settig a Threshold for Dyamic Adustmet Accordig to obtaied credibility of both arties, adust the resective iitial threshold K 0 K = (1 ) K0 (4) C Calculatio of Certificate Loss The basic value of rivacy for a certificate is marked as ϕ : ϕ [0,1] Whe the certificate is ulocked, the eed to rovide more certificates idicates that the rivacy level of a certificate is higher, i other words, disclosure eeds to reach the threshold The formula of calculatig the disclosure loss of a certificate is m i τ m κ ϕ ( ) τ ϕ ( ) ϕ0 (5) U = c s + i i i which κτ, are the comesatio factors ϕ 0 is the basic value or loss of certificates, divided ito ublic certificates ad rivacy certificates D Choosig Policy Comare the calculated value with the threshold value, i order to determie whether the ext egotiatio certificate achieves the coditios of iteractio The followig formula is used to calculate olicy A( ) { * ( ) } { * ( ) } 1 K Max K ci, s, U A( ) = 0 K < Max K ci, s, U i which the situatio of A= ( ) 1meas that the curret certificate ca cotiue to the ext ste of iteractio, the (6) value 0 meas that the coditio of iteractio is reached, eedig to re-cosult E Process of Dyamic Game A comlete rocess of cosultatio ca be exressed as follows ( ) ( ) Γ= Mi A Mi U (7) That is, each game ca obtai the best iteractio of certificates through the miimum utility IV PROCESS OF CONSTRUCTING THE GAME TREE A Maig Rules The actual egotiatio rocess is very comlex, ad it ca simlify i these coditio of covetio: (1)The resource requestor C ad the resource rovider S are both comletely ratioal (2) The resource requestor C ad the resource rovider S will ursue the maximum icome for themselves i the remise of isurig to costruct trust (3) The resource requestor C ad the resource rovider S ca obtai couterart s access cotrol strategy via egotiatio As for the study of automated trust egotiatio, access cotrol rules usually use the disuctive aradigm I the rocess of dyamic game, maig relatioshi should satisfy the followig coditios, i order to traslate the egotiatio sequece ito the costructio of the game tree (1) The aradigm for requested resource is R { Ci} { C}, i which R reresets the requested resources, ad C ad i C are eeded disuctive exressios of certificates by the requests, with maig aradigm show i Figure 2 (a) (2) The couctive aradigm for certificate requiremet is Sk { Ci} { C}, i which S k reresets coditioal disclosed certificate by either arty of egotiatio, ad C i ad C are eeded couctive exressios of certificates by the requests, with maig aradigm show i Figure 2 (b) (3) The aradigm to termiate egotiatio isck T, i which C k is ucoditioal disclosed certificate by either arty of egotiatio, usually reresetig the ed of the egotiatio The disuctive method for comositio is as follows S { C} { C } C T k i k

4 JOURNAL OF SOFTWARE, VOL 8, NO 10, OCTOBER Ste7 Calculate the rofit or the loss set U of both arties, as the leaf odes of the tree Ste8 Ed the costructio of the game tree V ALGORITHM OF DYNAMIC GAME FOR AUTOMATED TRUST NEGOTIATION (a) resource request (b) couctive exressio (c) egotiatio termiatio Figure 2 Maig relatioshi betwee egotiatio sequece ad game tree B Costructio of the Game Tree The costructio of a game tree is divided ito two stages The first stage is to costruct the tye of the tree, the basis ad method of which is maig rules ad the thought of recursive iteractio The secod stage is to calculate the corresodig loss or utility, ad to assess ad select aroriate cosultatio sequece The stes for costructio are as follows Ste1 Iitialize the tree as a emty oe, deoted byt 0 Ste2 Add the requested resource R tot 0, as the root ode Ste3 Perform disuctive decomositio of access cotrol rules for R, ad use all sub-tyes by the decomositio as the root odes of the ext layer of odes for subset of access cotrol rules, with the maig mode R { C} { C } Ste4 Server resoses to subset of access cotrol rules for Cliet, ad accordig to the maig mode Ck { Si} { S } requests the certificate set of Cliet i a reversed way, with its rules as the ext-layer odes for the tree Ste5 Cliet resoses to subset of access cotrol rules for R, ad accordig to the maig mode Sk { Ci} { C} requests the certificate set of Server i a reversed way, with its rules as the ext-layer odes for the tree Ste6 Reeat Stes (4) ad (5), util the ed of a cycle of access rules C k T or circular deedecy existig for the certificate i A Algorithm of Dyamic Game for Automated Trust Negotiatio From the aalysis i Sectio 4, the algorithm of dyamic game is summarized as follows Iut arameters: Credetials ad Strategy // Credetials is the set of certificates of both arties, ad resources are also see as certificates here // Strategy is the set of strategies of both arties for iteractio Outut arameters: Tree ad U // Tree is the geerated game tree // U is the loss of utility, calculated accordig to the formula i Sectio 3 Tree = φ Credetials = { R, Ci, S } Strategy = { k } Select the strategy request R from Strategy Strategy = Strategy { R} While Strategy φ do For each sub _ strategy do If Ci S Credetials the Re cursio sub _, If C S True the ( strategy Credetials) i Create a ormal brach Calculate U s ad U c Edif else Create a blak or cycle brach Calculate U s ad U c Edif Tree = Tree { brach} Edfor Strategy = Strategy { k } Edwhile retur OtimalStrategy Tree U U (, s, c ) B Comlexity Aalysis of Algorithm Accordig to the aalysis o dyamic game algorithm for automated trust egotiatio, the worst case is circular

5 2672 JOURNAL OF SOFTWARE, VOL 8, NO 10, OCTOBER 2013 deedecy of certificates, ad the time comlexity for 2 this case is ON ( ), i which N = C is the umber of certificates umber Ad the best case is for the first time to directly create the smallest brach, ad the time comlexity for this case will show a liear time comlexity OC ( ) I geeral, mea time comlexity to create ad calculate the whole tree is O(lg N ) the formig of circular deedecy for a certificate i the last brach also causes the trust ot to be established Ad there are three actio sequeces that ca build trust, as show i Table 2 VI EXAMPLE ANALYSIS This sectio will aalyze the egotiatio rocess of dyamic game i the case of icomlete iformatio through a examle It is assumed that the certificates ad olicies for both arties are show as Table 1 As is show i Table 1, the reresetatio of olicies is the disuctive aradigm The game tree for examle is show i Figure 3 Through dyamic game, the etire game tree ca be rued, ad the trust relatioshi ca be established by calculatio ad selectio of otimal reveue from the rofits TABLE I POLICIES FOR THE EXAMPLE Figure 3 A game tree for examle See from Table 2, the sequece C6 C7 C8 S4 T is a best sequece, ad the result of the game is to build the trust relatioshi with as little as ossible exosure of a certificate ad rivacy loss I additio, the reaso of sequecec 1 Susesio is that the resource requester lacks the certificatec 1, which leads to susesio of the egotiatio Ad sequeces C 2 C 4 S 1 S 5 C 5 C 7 S 2 S 4 C 5 ad C3 C7 S1 S5 C5 S2 S4 C geerate circular 5 deedecy of the certificate C 5, ad the cosultatio caot be erformed TABLE II PATH ANALYSIS Ad trust caot be established if the actio sequece for oe arty caot rovide the certificate C 1 I additio,

6 JOURNAL OF SOFTWARE, VOL 8, NO 10, OCTOBER average um ber of disclosured certificates eager strategy rudet strategy dyamic game strategy umber of certificates Figure 4 The comariso of simulatio results I a simulatio eviromet, the umber of certificates ad access cotrol olicies ad differet settigs of the rivacy will roduce differet results I order to better model the actual effect, the certificate ad the strategy to obey that a certai distributio is radom is reasoable Here is a selectio of the ethusiastic model ad the cautious model to serve as cotrast, ad the average disclosed certificate umber is as the comariso obect, as is show i Figure 4 VII CONCLUSION I order to solve the rivacy rotectio roblem i the rocess of automated trust egotiatio, this aer rooses a automated trust egotiatio model based o dyamic game of icomlete iformatio This aer uses dyamic game for establishig dyamic game rocess ad discusses the model through examle aalysis The work of this aer ca be summarized as follows (1) It itroduces the thought of dyamic game through aalysis; a automated trust egotiatio model, ad a game model for automated trust egotiatio is roosed (2) It alies the rocess of dyamic game ito establishmet of automated trust egotiatio A dyamic egotiatio mechaism is established, icludig calculatio of trust degree evaluatio, settig of a threshold for dyamic adustmet, calculatio of certificate loss, choosig of Policy, ad rocess of dyamic game (3) It rovides the algorithm of establishig dyamic game rocess Maig rules betwee egotiatio sequece ad game tree, ad stes for costructio of the game tree are roosed I additio, a algorithm of dyamic game for automated trust egotiatio is reseted, ad the algorithm comlexity is aalyzed (4) It gives a examle of automated trust egotiatio, ad the egotiatio rocess of dyamic game i the case of icomlete iformatio through the examle is aalyzed ACKNOWLEDGMENT This work has bee suorted by the Geeral Program for Natioal Natural Sciece Foudatio of Chia (No ), the Natioal Natural Sciece Foudatio of Chia for Youg Scholars (No ), the Key Proect for Natural Sciece Foudatio of Hubei Provice i Chia (No 2010CDA011), the Geeral Program for Natural Sciece Foudatio of Hubei Provice i Chia (No 2011CDB075, No 2012FFB00601), the Key Proect for Scietific ad Techological Research of Educatio Deartmet of Hubei Provice i Chia (No D , No D ), the Provicial Teachig Reform Research Proect of Educatio Deartmet of Hubei Provice i Chia (No ), the Key Proect for Scietific ad Techological Research of Wuha City i Chia (No ), ad the Twilight Pla Proect of Wuha City i Chia (No ) REFERENCES [1] Bailig Liu, "Efficiet Trust Negotiatio based o Trust Evaluatios ad Adative Policies", Joural of Comuters, vol 6, o 2, ,2011 [2] Yu Wag, Qiuwei Yag, "Eveloe Protocol for Privacy Protectio", Joural of Covergece Iformatio Techology, vol 7, o 1, , 2012 [3] Aa C Squicciarii, Federica Paci, Elisa Bertio, "Trust establishmet i the formatio of Virtual Orgaizatios", Comuter Stadards & Iterfaces, vol33, o1, 13-23, 2011 [4] Wai-Khue Cheg, Boo-Yaik Ooi, Huah-Yog Cha, "Resource federatio i grid usig automated itelliget aget egotiatio", Future Geeratio Comuter Systems, vol26, o8, , 2010 [5] Deqig Zou, Shagxi Du, Weide Zheg, Hai Ji, "Buildig Automated Trust Negotiatio architecture i virtual comutig eviromet", The Joural of Suercomutig, vol55, o1, 69-85, 2011 [6] Zuo Che, Qiuwei Yag, Xi Wa, Yuaya Tu, Fei Yu, Che Xu, "Automated Trust Negotiatio with Time Behavior", Joural of Networks, vol 6, o 8, , 2011

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