An enhanced dynamic-id-based remote user authentication protocol with smart card

Transcription

1 Internatonal Journal of Engneerng Advanced Research Technology (IJEART) ISSN: Volume-2 Issue-4 Aprl 206 An enhanced dynamc-id-based remote user authentcaton protocol wth smart card aoran Chen Janhna Chen an Shen Abstract Wth the bloomng development of network technologes remote user dentty authentcaton s becomng more more mportant to ensure that only the legal user can consume the servces of the system Recently Sh et al presented an mproved remote user authentcaton scheme wth key agreement that attempts to resst varous attacks to acheve perfect user anonymty owever n ths paper we shall show that ther scheme s prone to smart card loss attack offlne password guessng attack mpersonaton attack server spoofng attack What s more Sh et al scheme fals to provde user anonymty as they clamed Then we put forward an enhanced protocol whch s more secure sutable for the applcaton envronment Index Terms dynamc dentty; mutual authentcaton; protocol; smart card I INTRODCTION Owng to the rapd progress n wreless network technology t s becomng more more convenent for users to enjoy desred servces from servce provder servers At the same tme t rases securty concern about a system s protected servces mght be utlzed by llegal users n a fraudulent manner As a result how to dentfy a remote user n the open network becomes a crucal ssue To solve ths problem n 98 Lamport [] proposed the frst password-based scheme by employng a one-way hash functon Due to ts smplcty that the password s easy to memorze password-based authentcaton schemes have been wdely used to valdate the remote user Snce then numerous [2-5] password-based protocols were proposed owever n these schemes the server has to store a senstve verfer table that contans the passwords of all the regstered users One securty threat of ths knd of schemes s that once ths password-verfer table s leaked all the regstered users password wll be at rsk Thus some [6-] user authentcaton schemes are desgned wth no verfer table Owng ts portablty low cost cryptographc computatonal capacty nature the smart card s wdely used n these protocols owever based on fxed dentty schemes [-] may leak the regstered users nformaton to malcous attackers further damage users prvacy To preserve users prvacy Das et al [4] proposed the frst dynamc ID-based two-factor authentcaton scheme n 2004 whch they clamed s secure aganst ID-theft can resst the reply attacks forgery attacks guessng attacks nsder attacks stolen verfer attacksnfortunately n 2009 Wang et al [5] ponted out that Das et al s scheme s completely nsecure for ts ndependence of usng passwords Moreover ther protocol suffers from mpersonaton attack fals to provde mutual authentcaton user anonymty To ncrease securty they presented an mproved verson whch was revealed by Chang et al [6] not a true dynamc-dentty based scheme n fact possesses securty holes n the password change phase because an attacker can update the password n a user s smart card at hs wll Then they proposed an untraceable remote user authentcaton scheme wth verfable password update nfortunately Kumar et al [7] found that the scheme of Chang et al s completely nsecure So Kumar et al also put up wth ther mproved scheme In 205 Sh et al [8] presented an mprovement scheme of Kumar et al s protocol they clam that ther scheme can resst varous attacks acheve user anonymty owever based on the securty analyss we fnd that ther scheme s vulnerable to smart card loss attack offlne guessng attack user mpersonaton attack server spoofng attack Besdes ther protocol cannot provde user anonymty In ths paper an enhanced dynamc-id-based remote user authentcaton scheme wth smart card s proposed We wll llustrate that wth lttle computatonal cost our protocol can not only wthst varous attacks but also acheve truly user anonymty The rest of ths paper s organzed as follows: n secton 2 we revew Sh et al s scheme brefly Then ther scheme s analyzed n detal n secton Next we proposed an enhanced dynamc-id-based remote user authentcaton scheme wth smart card n secton 4 In secton 5 we dscuss the securty of our protocol provde detals of the proof Secton 6 descrbes performance evaluaton Fnally we draw a concluson n secton 7 II REVIEW OF SI ET AL S SCEME We wll brefly revew Sh et al s protocol n ths secton It conssts of the followng four phase: regstraton phase logn phase authentcaton phase password change phase The notatons used throughout ths paper are descrbed as follows: / / S : ser/attacker/server; ID : Identty of ; PW : Password of ; CID : Dynamc dentty of ; SC : Smart card of ; r : nque rom number assgned to by S ; r : A rom number selected by the smart card; T T2 T : Current tmestamps; h() : One way hash functon; Ek () : A symmetrc key encrypton algorthm k s the secret key; : Bt-wse exclusve-or () operaton; 49 wwwjeartcom

2 An enhanced dynamc-id-based remote user authentcaton protocol wth smart card : Connecton operaton; 2 Regstraton Phase If a user would lke to regster as a legal user of the system he would perform the followng procedures: ) The user frst chooses hs dentty ID password PW freely chooses a rom number a to computes the value R h( a PW ) transmts server va a secure channel 2) On recevng the message ID R ID R to the the server chooses a rom number r for every regstered user then computes the value of TN h( h( ID ) x) R TY r h( h( ID ) x) R TD h( ID r R ) TE r h( y x) he stores TY TD TE nto SC send t together wth the value TN to over a secure channel ) When the user receves the message form the server S he computes the value of A h( ID pw ) a TM TN a keeps the values 22 Logn Phase A TM n SC After executng the regstraton phase becomes the legal user of the system In order to communcate wth the server nputs hs dentty ID password PW nto the smart card then SC performs the followng steps: ) Frst smart card computes a A h( ID PW ) R h( a PW ) then he further calculates the value of h( h( ID ) x) TM a R r TY h( h( ID ) x) R 2) Next smart card SC TD h( ID r R ) computes checks whether the equaton TD TD holds or not f t holds then the smart card SC contnues to calculate h( y x) r TE TN TM a Otherwse SC termnates the sesson ) At last smart card SC gets the current tmestamp T computes user s dynamc dentty CID h( ID ) h( TN r ) then SC further calculates the value of TG TN h( r ) TB TN R After that SC romly choose a number b to calculate the value of Q h( h( ID ) b) then SC cam obtan the value of DS TB Q TC h( TN r Q ) TF r ( h( y x) ) After that SC transmts the logn request CID TG TC TF DS T to S 2 Authentcatone Phase In ths phase both the user the server start to take the followng steps to authentcate the legtmacy of each other further consult the common sesson key ) pon recevng the logn request S obtan the CID TG TC TF DS T from current tmestamp T2 examnes the valdty of T That s f T2 T T holds T s vald S contnues to execute the next step If not so the procedure wll be aborted 2) Next S retreves the values r TF h( y x) T TN TG h( r T ) by usng hs prvate key x then the server contnues to compute h( ID ) CID h( TN r T ) TB h( h( ID ) x) Q TB DS Next the server checks whether the equaton TC? h( TN r Q ) holds or not If not S termnates the sesson Otherwse s authentcated as a legal user by S At last S gets the current tme T to compute sends the response message mmedately V h( TB r T ) V T to ) pon recevng V T from freshness of T If T s fresh V h( TB r T ) S compares valuev f they are equal then server by Otherwse examnes the contnues to compute V wth the stored S s authentcated as a vald drops the message termnates the sesson 4) Fnally computes hs sesson key SK h( TB r T T h( y x) Q ) u S calculates SKs h TB r T T h y x Q ( ( ) ) From the dscusson above we know that TB TB Q Q Thus the server S user generate the same to encrypt or decrypt the sesson key SK SKu SKs messages transmtted between them 24 Password Change Phase Ths phase s carred out when the user wants to update hs password wthout connectng the server Then he should execute the followng steps: ) nserts hs smart card SC nto the card reader nputs hs dentty ID password PW so as to request for password changng 2) Next SC verfes the correctness of TD n the way the 50 wwwjeartcom

3 logn phase performs IfTD the password change request Only f TD proceeds on ) Fnally SC remnds the user password Internatonal Journal of Engneerng Advanced Research Technology (IJEART) ISSN: Volume-2 Issue-4 Aprl 206 SC rejects TD smart card TD wll SC to nput the PW computes the value of A h( ID PW ) a R h( a PW ) nd compute SC contnues to TM TM R R TD h( ID r R ) Then SC replaces the stored values A TD TM TY wtha TD TM TY III SECRITY ANALYSIS OF SI ET AL S PROTOCOL Before analyzng of Sh et al s protocol we frst pont out that smart card can no longer be deemed as fully tamper-proof devcewhen a user lost hs smart card the adversary can extract the nformaton stored n the smart card by means of analyzng the power consumpton whch has proposed by Kocher et al [9] Messerges et al [20] In ths phase we llustrate that there exsts many securty holes n Sh et al s scheme descrbe them n detals Smart Card Loss Attack Off-lne Password Guessng Attack If the smart card of the user was stolen by an adversary who s also a legal user of the system has hs own smart card SC suppose can ntercept the logn request CID TG TC TF DS T of We pont out that Sh et al s scheme s vulnerable to offlne password guessng attack owng to smart card loss the procedure s as follows: Step : extractsa TM TY TD TE from hs smart card SC computes a A h( ID PW ) R h( a PW ) r TY h( h( ID ) x) R thus can obtan the system constant value h( y x) by computng h( y x) TE r Step 2: As the attacker obtans the logn request CID TG TC TF DS T of values together wth the value h( y ) he can use these x obtaned n Step to compute r TF h( y x) T TN TG h( r T ) TN TG h( r T ) Step : When the user s smart card SC was stolen by an adversary he can extract the a messages A TM TY TD TE h( ) stored n SC Then he can obtan the value of a by usng the extracted value TM the value TN whch was computed n Step 2 ths s because a TM TN Consequently the attacker can obtan the hashed value h( ID PW ) by calculatng h( ID PW ) A a Step 4: Now launches offlne password guessng attack usng the mportant value h( ID PW ) Frst chooses the cdate dentty ID password PW from two ndependent dctonares respectvely Step 5: The attacker further computes the value of h( ID PW ) compare t wth h( ID PW ) f they are equal t ndcates that the attacker has successfully guessed the rght dentty password of Otherwse returns to Step 4 untl he fnally seek out the true dentty password of In ths way the attacker can eventually obtan the dentty password of the system s arbtrary user ence Sh et al s protocol suffers from smart card loss attack offlne password guessng attack 2 ser Impersonaton Attack When the smart card of the legal user was stolen or obtaned by the attacker he had ntercepted the logn request from the open network then he can launch offlne password guessng attack to obtan the dentty password of the user as we explaned n secton In ths case the attacker possess the followng prvate values: ID PW a mpersonate R r TM TN We show that he can n the followng manner wthout a smart card: ) The attacker acqures the current tmestamp T computes the followng values: CID h( ID ) h( TN r T ) TG TN h( r T ) TB TN R n order to compute DS TC TF he frst compute Q h( h( ID ) x) next the attacker can obtan these values by computng DS TB Q TC h( TN r Q T ) TF r h( y x) T transmts the logn request CID TG TC TF DS T to the server 2) Obvously the attacker s logn request CID TG TC TF DS T wll be accepted by the server because t s computed by usng the vald dentty ID password PW So n Sh et al s protocol the attacker 5 wwwjeartcom

4 An enhanced dynamc-id-based remote user authentcaton protocol wth smart card can mpersonate the legal user of the system Therefore ther scheme s vulnerable to user mpersonaton attack Server Spoofng Attack As descrbed n secton secton 2 the attacker can obtan the system value h( y x ) whch s common for all users Subsequently he can get the dentty ID password PW of the user by launchng offlne password guessng attack then he computes the value of a A h( ID PW ) R h( a PW ) n order to get the value of h( h( ID ) x) TM a R Wth these values n h can masquerade the legal server smply n the followng procedures ) At frst ntercepts the logn request then computes CID TG TC TF DS T of r TF h( y x) T TN TG h( r T ) TB h( h( ID ) x) 2) After that acqures the current tme T A h( TB r T ) calculates messageatto send the response ) Snce the tmestamp T s fresh that had successfully guessed the dentty ID password PW of the response message AT wll certanly pass the authentcaton test at the user s sde In ths way the attacker can trck the user mtatng the legal server 4 ser s Identty s Traceable by Based on the dscusson n secton the attacker has the ablty to obtan the dentty password of the system s legal user f he has the smart card of the user ntercepted all messages transmtted n a logn-authentcaton sesson That s the adversary can obtan the dentty of the arbtrary user so we can see that the user s dentty s traceable So Sh et al s scheme could not protect user s prvacy as they clamed IV OR ENANCED PROTOCOL A fresh protocol s proposed n ths secton whch can resst the attacks descrbed n the prevous sectons The proposed scheme has the same four phases lke Sh et al s scheme The detals of the proposed scheme are shown below 4 Regstraton Phase Before a user logn n the remote server become the legal user of the system he should execute the followng steps as shown n Fgure 2: ) Frstly chooses hs ID PW a rom number a computes the value of R h( PW a) next transmts the message S va a secure channel ID R to 2) pon recevng the message ID R from generates a rom number r for the correspondng user contnues to compute the value of TN h( ID x) R TY r h( ID x) TD h( ID r R ) TE Ex( y ID ) r Then the server S keeps TY TD TE h( ) nto the smart card SC delvers SC TN to Fgure 2 The Regstraton Phase of The Proposed Scheme 42 Logn Phase When a regstered user would lke to logn nto the server S access the servces nserts smart card SC nto a termnal devce nputs hs dentty ID password PW then SC performs the followng steps whch are shown n Fgure : ) Frstly the smart card SC successvely computes the followng values: a A h( ID PW ) R h( a PW ) h( ID x) TM a R computes the value of r TY h( ID x) TD h( ID r R ) 2) If TD TD SC contnues to calculate the value Ex ( y ID ) TE r we wrte TF Ex( y ID ) for smplcty Otherwse SC drops the sesson ) Then SC acqures the current tmestamp T computes the user s dynamc dentty CID h( ID ) r TG TN h( r ) TB TN R After that the smart card SC generates a rom number r further computes the value of Q h( ID r) DS TB Q TC h( TN r Q ) then SC sends the S 52 wwwjeartcom

5 logn request 4 Authentcaton Phase Internatonal Journal of Engneerng Advanced Research Technology (IJEART) ISSN: Volume-2 Issue-4 Aprl 206 TF CID TG DS TC T to S In ths phase the user server take the followng steps to acheve mutual authentcaton further consult the common sesson key ) On recevng the logn request TF CID TG DS TC T S obtans the current tme T 2 verfes the valdty of T Only when T s fresh wll the server S contnue further Otherwse S rejects all the logn requests Subsequently S decrypts TF wth the secret key x then he can obtan the user s dentty SKs h( TB r T Q ) ( ) ( ) ( ) computes SKs h( TB r T Q ) S can compute the value of ( ) key SK SKu SKs h TB r T T Q r CID h ID T TN TG h r T TB h ID x Q DS TB so TC h TN r Q T 2) Next S checks whether the computed TC the stored TC are equal or not If not S drops the sesson Only f TC TC wll the user be authentcated the sesson proceeds further ) S acqures the current tme T to calculates V h( TB r T ) delvers the message VT to 4) pon recevng the response message VT SC checks T for freshness If T s fresh SC computes V h( TB r T ) verfes whether the equaton V V holds or not If so authentcates S as a legal server or else SC stops the procedure neglect the response message Fnally S computes hs sesson key smart card SC ence they have negotated the common sesson ( ) Fgure Logn Authentcaton Phase 44 Password Change Phase When the user wants to update hs password wthout connectng the server Then he should perform the followng steps: ) Frstly nserts hs smart card nto the card reader nputs hs dentty password to request for changng hs password 2) Next SC verfes the correctness of TD n the way the logn phase performs If TD TD SC drops the password change request But after thrce falures SC wll get blocked the user must enter the prvate unblockng key to re-actvate hs smart card Only f TD TD wll SC proceed on ) Then SC remnds to nput the password PW computes the value of ( ) h( a PW ) ( ) A h ID PW a R TM TM R R computes TD h ID r R Fnally SC stores A TD TM n place of A TD TM respectvely 5 wwwjeartcom

6 An enhanced dynamc-id-based remote user authentcaton protocol wth smart card ser Smart card SC Inserts ID PW ID PW Inserts PW PW Compute a A h( ID PW ) R h( a PW ) h( ID x) TM a R r TY h( ID x) Check TD? h( ID r R ) For TD TD Allow to nput password Compute A h( ID PW ) a R h( a PW ) TM TM R R TD h( ID r R ) ReplaceA TD TM wtha TD TM Fgure 4 Password Change Phase V SECRITY ANALYSIS In ths secton we wll demonstrate that our enhanced protocol s secure aganst varous attacks dscussed n the prevous sectons the detals are shown n the followng content: 5 Ressts repay attack Replay attack s an offensve acton through whch an attacker may mpersonate the legal user or the server by repayng the prevous message In our protocol we assume that the attacker had ntercepted the prevous authentcaton nformaton we use tmestamp T to prevent the attacker from repayng the request message lkewse T s used to resst the attacker reusng the response message to mtate the vald serverths s because both the request response message undergo the tmestamp freshness check through the smlar freshness verfcaton process at each other s sde Therefore our protocol can wthst repay attack 52 Ressts offlne password guessng attack Off-lne password guessng attack means that the attacker can use user s smart card the nteractve nformaton between the legal user the server to successfully guess the user s password off-lne In ths scheme consder that an attacker obtans a user s smart card ether by stealng or lost by the user Then he can extract all secret values SC Among these A TM TY TD TE stored n values: A h( ID PW ) a TM h( ID x) R a TY r h( ID x) TD h( ID r R ) TE E ( y ID ) r due x to the property of one way hash functon we cannot retreve the values TD And n order to obtan ID r R out of the value h( ID x ) from TM the attacker should know the rom number a the password PW of But he cannot guess the two values a PW at the same tme And as A contans another unknown value ID could not retreve these values from A ether As a result s unable to compute the value : r TY h( ID x) In a word cannot obtan these values x r h( ID x) wthout knowng these values t s mpossble for hm to guess an arbtrary password PW verfy hs guess usng these fve values: A TM TY TD TE Next suppose that have eavesdropped the logn request TF CID TG DS TC T of we show that he stll cannot usng these values to verfy hs guess From the logn phase we can obtan the value TF Ex( y ID ) CID h( ID ) r TG TN h( r ) TB TN R Q h( ID r) successvely we can get by calculatng the value of: DS TB Q TC h( TN r Q ) Smlarly TN h( ID x) R R h( a PW ) can be obtaned from the regstraton 54 wwwjeartcom

7 Internatonal Journal of Engneerng Advanced Research Technology (IJEART) ISSN: Volume-2 Issue-4 Aprl 206 phase So we have TG h( ID x) h( a PW ) h( r ) TB h( ID x) lkewse we have DS h( ID x) h( ID r) TC h( TN r h( ID r) T ) In each tem of TF CID TG DS TC T t contans at least two unknown values for the attacker t s not possble for hm to guess two unknown values n polynomal tme Thus the proposed protocol s secure aganst the most damagng attack: offlne password guessng attack 5 Ressts prvleged nsder attack Prvleged nsder attack happens when an nsder of the system lke the admnstrator obtans the password of the legal user by montorng the regstraton message transmtted from the user to the server through a secure channel In the proposed scheme the user use a romly selected number a submts hashed value R h( a PW ) to protect hs password nstead of sendng t n a plan text As the attacker doesn t know the rom number a the password PW t s mpossble for hm to smultaneously guess two values n polynomal tme Thus t s not hard to see that the proposed protocol s secure aganst prvleged nsder attack 54 Ressts user mpersonaton server masqueradng attack In the proposed scheme f an attacker would lke to mpersonate he should compute the logn request TF CID TG DS TC T to pass the server s verfcaton Wthout knowng the dentty ID password PW of cannot calculate the rom number a not to menton R h( ID x ) even f he has the smart card of And he cannot synchronously guess the possble dentty password of the user because he has no opton to verfy hs guessthus t s not feasble for to launch user mpersonaton attack Smlarly assume that the attacker ntercepted the logn requesttf CID TG DS TC T of In order to successfully mpersonate a legal server he should compute a vald response message rt as an answer to the logn request From the dscusson above cannot compute h( ID x ) he doesnt know the secret key x of the server so he cannot decrypt TF to get ID therefore he cannot calculate r CID h( ID ) Based on the dscusson above t s not feasble for an attacker to launch server masqueradng attack on the proposed scheme 55 Ressts smart card loss attack Suppose an attacker obtans the smart card of the user eavesdrops the nformaton transmtted between the two sdes from the open network Secton 42 shows that the attacker cannot obtan any useful nformaton such as x r h( ID x ) even f he has stolen the smart card of ntercepted all messages transmtted n a logn-authentcaton sesson ence a lost or stolen smart card s helpless for to obtan the prvate nformaton of the user Consequently the securty of the proposed protocol remans unaffected to smart card loss attack 56 Mutual authentcaton In our protocol the server ensures that the logn request s from the legal user by means of checkng whether TC s h( TN r Q T ) equal to or not after acceptng the logn request dependng upon the freshness of the tmestampt Lkewse the user authentcate the server by means of verfyng whether the equaton V V holds or not after acceptng the response request dependng on the freshness of the tmestamp T Thereforethe proposed protocol provdes secure mutual authentcaton between the legal user the vald server VI PERFORMANCE COMPARISON AND FNCTIONALITY ANALYSIS Effcency functonalty comparsons among the proposed protocol the related three protocols: Sh et at s [8] Kumar et al s [9] Chang et al s [20] are shown n ths secton Table shows the effcency comparson among the four protocols Table 2 shows the functonalty comparson among these schemes In Table each scheme conssts of fve parts: regstraton phase logn phase authentcaton phase password change phase the sum of computatonal complexty For convenence some notatons whch wll be used n the effcency comparson are gve n the followng: t : the tme complexty for one way hash functon ; t E : the tme complexty for symmetrc encrypton; t : the tme complexty for operaton ; Table Computatonal Cost Computatonal cost comparson Ours Sh et al Kumar et al Chang et al Regstraton phase 55 wwwjeartcom

8 An enhanced dynamc-id-based remote user authentcaton protocol wth smart card 6t 5t t 6t 8t 5t 5t E Logn phase 0t 9t t t 2t 0t 8t t 4t E t t Authentcaton phase Password change phase Sum of computatonal complexty t 6t t 4t 8t t 7t 6t 0t E 7t 6t 0t 7t 6t 6t 8t 2t 26t 26t t t 5t 24t 26t 8t 27t E Table shows that the proposed agreement takes more computatons cost than those of others due to the applcaton of the symmetrcal encrypton technque But f merely hash arthmetc operaton are ntroduced n a scheme t s unable to guarantee the safety of the scheme As we can clearly see from the Table that the other three protocols whch are desgned only wth one way hash functon the operaton are prone to varous attack such as smart card loss attack offlne password guessng attack user mpersonaton attack server masqueradng attack Thanks to the adopton of symmetrcal encrypton algorthm the proposed scheme can resst the above attacks provde perfect user anonymty ence our protocol s sutable for the applcaton envronment Table 2 Securty Comparsonom Securty comparson Ours Sh et al Kumar et al Chang et al Resstng nsder attack Y Y Y N Resstng smart card loss attack Y N N N Resstng mpersonaton attack Y N N N Resstng server spoofng attack Y N N N Offlne password guessng attack Y N N N Offlne password guessng attack Y N N N Resstng repay attack Y Y Y Y Provdng mutual authentcaton Y N N N Provdng mutual authentcaton Y N N N From Table 2 t s obvous to see that our protocol has many mportant secure propertes Compared wth the other three related works our scheme s secure aganst nsder attack smart card loss attack mpersonaton attack server spoofng attack password guessng attack repay attack Furthermore the proposed scheme can provde mutual authentcaton user anonymty VII CONCLSION In ths paper we frst brefly revewed an mproved anonymous remote user authentcaton scheme based on dynamc dentty But after basc secure analyss of Sh et al s protocol we found that ther scheme s stll subject to varous attacks lack of user anonymty To overcome the weakness of Sh et al protocol we presented an enhanced dynamc-id-based remote user authentcaton scheme wth smart card Through securty analyss performance comparson we have llustrated that wth lttle ncrease n computatonal cost the proposed key agreement can resst varous attacks provde perfect user anonymty REFERENCES [] Lamport L (98) Password authentcaton wth nsecure communcaton Communcatons of the ACM [2] N aller The S/KEY one-tme password system Proceedngs of the ISOC Symposum on Network Dstrbuted System Securty 994 pp 5 57 [] Peyravan M (2000)Methods for protectng password transmsson Computers & Securty 9(5) [4] Y L Tang M S wang C C Lee A smple remote user authentcaton scheme Mathematcal Computer Modelng vol 6 Issues -2(2002) pp wwwjeartcom

9 Internatonal Journal of Engneerng Advanced Research Technology (IJEART) ISSN: Volume-2 Issue-4 Aprl 206 [5] Ln C (200)A password authentcaton scheme wth secure password updatng Computers & Securty22() [6] C L su Securty of Chen et al Remote user authentcaton scheme usng smart cards Computer Stards Interfaces vol 26 no (2004) pp [7] W C Ku S M Chen Weaknesses mprovements of an effcent password based remote user authentcaton scheme usng smart cards IEEE Transactons on Consumer Electroncs vol 50 no (2004) pp [8] Y F Chang C C Chang Authentcaton schemes wth no verfcaton Table Appled Mathematcs Computaton vol 67 no 2 (2005) pp [9] ed Chen J & u J (20)Further mprovement of Juang et al s password-authentcated key agreement scheme usng smart cards Kuwat Journal of Scence Engneerng 8(2A) [0] Juang W Chen S & Law (2008)Robust effcent password-authentcated key agreement usng smart cardsieee Transactons on Industral Electroncs 55(6) [] Yang G et al (2008)Two-factor mutual authentcaton based on smart cards passwords Journalof Computer System Scences 74(7) [2] Xu J Zhu W & Feng D (2009) An mproved smart card based password authentcaton schemewth provable securty Computer Stards & Interfaces (4) [] Yeh K et al (200)Two robust remote user authentcaton protocols usng smart cards Journal of Systems Software 8(2) [4] M Das A Saxena V Gulat A dynamc d-based remote user authentcaton scheme IEEE Trans ConsumElectron 50 (2) (2004) [5] Y Wang J Lu F Xao J DanA more effcent secure dynamc d-based remote user authentcaton scheme Comp CommunSyst 2 (4) (2009) [6] Chang YF Ta WL Chang C ntraceable dynamc-dentty-based remote user authentcaton scheme wth verfable password updateint J CommunSyst 20 [7] S Kumar M K Khan X L An mproved remote user authentcaton scheme wth key agreement Computers Electrcal Engneerng vol 40 no 6 (204) pp [8] Y Sh Shen Y Y Z J Chen An mproved anonymous remote user authentcaton scheme wth key agreement based on dynamc dentty InternatonalJournal of Securty Its ApplcatonsVol9No5(205) pp [9] P Kocher J Jaffe B Jun Dfferental power analyss Proceedngs of advances n cryptology CRYPTO 99 (999) pp [20] T S Messerges E A Dabbsh R Sloan Examnng smart-card securty under the threat of power analyss attacks IEEE Trans Comp vol 5 no 5 (2002) pp wwwjeartcom