SECURE COMMUNICATION BY USING MULTIPLE KEYS HAVING VARIABLE LENGTH IN A REAL TIME ENVIRONMENT FOR MULTIPLE STATIONS

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1 Journal of Engneerng Scence and echnology Vol. 7, No. 4 ( School of Engneerng, aylor s Unversty SECURE COMMUNICAION BY USING MULIPLE KEYS HAVING VARIABLE LENGH IN A REAL IME ENVIRONMEN FOR MULIPLE SAIONS AJAY KAKKAR, *, M. L. SINGH, P. K. BANSAL 3 hapar Unversty, Patala, Punab, Inda ECE Department, Guru Nana Dev Unversty, Amrtsar, Punab, Inda 3 MIMI, Malout, Punab, Inda *Correspondng Author: aar_aay9@redffmal.com Abstract he number of securty attacs aganst networ s ncreasng dramatcally wth tme. o protect the model aganst these attacs; technques le passwords, cryptography, and bometrcs are used. Even multple passwords are not preferred due to low entropes. he bometrc s a very costly technque; moreover they may produce harmful effects to the body. Cryptography s used to avod unauthorzed access of data. It ncludes qute smple encrypton algorthm and eys generated from the data. hs paper deals wth the parameters such as number of users, falure rate of varous eys, recovery mechansm, encrypton, transmsson, decrypton and latency tme, etc.; requred for secure transmsson of data. he proposed algorthm shows that all the stages are mutually ndependent from each other. It also provdes the faclty to use compresson and re-encrypton technques. Keywords: Encrypton, S-Boxes, Paddng, Keys, Falure rate.. Introducton Securty of data s the prme requrement of all the organzaton. It can be acheved by usng varous technques such as passwords, cryptography, bometrcs and many more, but out of all these, cryptography wth good encrypton algorthm havng multple eys provdes relable model. Hacng s done on the nternet by creatng the spy-ware; whch s sent to the vctm s machne. User cannot realze t because after openng t, t wll be deleted automatcally. hen after ths moment as soon as user flls hs/her user name and password, t wll be sent to the attacer. At ths pont t s possble that the attacer can dsable the vctm s machne. 55

2 56 A. Kaar et al. Nomenclatures B Bandwdth of the channel b (t Data sgnal of the th user C Capacty of the channel C F Compresson factor D t Decrypton tme E r Re-Encrypton E t Encrypton tme E, E Frst and second level encrypton F Number of falures durng the nstallaton f c Centre frequency L t Latency tme R Data rate of bt (=/ b rt, (r+ Rectangular pulse n the nterval of S Sgnal power S, S,..., S n Statons S t Synchronzaton tme b me requred to transmt bt t ransmsson tme U, U,.., U n Users he normal wndow XP s easly haced by usng server software s wthout changng/obtanng the wndow password. Normally we observe that the system s loced by the admnstrator and one should requre username and password n order to access t. here are varous ways to acheve the securty n data communcaton such as; passwords, multple passwords, cryptography and bometrcs. hese technques are used to eep the data secured from the hacer. Passwords are not treated as relable for ths tas. It s easy to guess passwords due to ts short range. Cryptography s a technque used to protect the data from unauthorzed access. It s the best method of savng the documents from the compettors n busness. It conssts of two components Encrypton algorthm and Keys. here are many cryptographc algorthms avalable n the maret for encryptng the data. Encrypton s the process n whch orgnal data (plantext s converted nto the encoded format (cpher text wth the help of ey. he user s machne can be haced by two methods: Method : by pressng Ctrl+Alt+Del twce, t s observed that new operatng system (created durng the nstallaton process s avalable for the user havng username admnstrator and blan password. By pressng Enter you are able to do any nd of tas by usng that machne. Method : f new operatng system does not have blan password then restart the machne and press F8, go for safe mode command prompt type net user admnstrator. A new screen s avalable where you can put your new password or you may leave t blan. o protect the machne from these attacs encrypton s the best method. he ultmate am of cryptography s to provde the securty even f the hacer s able to access the data. Data securty s related wth both, physcal and wreless securty. he man motve of the hacer s s to destroy the wreless securty, means to Journal of Engneerng Scence and echnology August, Vol. 7(4

3 Secure Communcaton n a Real tme Envronment for Multple Statons 57 generate the vrtual attacs because all the systems are based upon the wreless that provdes the freedom of moblty to the users. Moreover t s not accepted that the nformaton avalable on the web always of hgh qualty. echnques and organzatonal solutons are requred to access and attest the qualty of data. hey should provde more effectve ntegrty semantcs verfcaton and the use of tools for the assessment of data qualty [,]. Real operatons requre mmedate response from the devce when called by the man staton. he factors should be ept n my mnd whle desgnng a networ are: ( Users (U, U,.., U n, ( ype of hardware/software, ( Channel Capacty, C, (v Number of falures durng the nstallaton, F, and transmsson (a, b, c,, Number of chec ponts, (v Encrypton, transmsson, decrypton, latency tme (E t, t, D t, L t, (v Level of protecton; frst and second level encrypton, E, E and re-encrypton, E r, (v Actve statons wth relable ey(s, (v synchronzaton tme, S t, (x Compresson factor, C F, and, (x Paddng. he obectves of ths wor are: - o acheve securty wth mnmum number of overheads. For ths the encrypton algorthm s qute smple and to acheve hgh degree of securty; multple eys are used generated from the data. - It s clear that eys play an mportant role n encrypton process, whch s a man part of cryptography. If the ey s slghtly changed then almost all the data s worthless. - Sometmes n transmttng the data, the length of data does not match wth the bt length offered by the encrypton process. herefore paddng technques are used to sort out the problem. - Key should be changed wth respect to tme because securty s not a product, t s a process. Wth the ncrease of tme the chances of model breaage ncreases. herefore the falure tme of each staton should be determned. If any staton goes down then recovery mechansm runs (n that encrypton s done by usng other ey, process called reencrypton. Agan falure rate s calculated f staton passes the test then the data s send to the next staton, otherwse partcular staton wll be cut-off from the model.. Proposed Model System-wde securty s always requred to mae sure that data s safe. By usng the nformaton about tmng, power consumpton, and radaton of a devce durng the executon of a cryptographc algorthm; cryptanalysts have been able to brea the system. So a motve should be to mae the combnaton secure. Practcal model conssts of transmtter(s and other processng unts capable to encrypt whch s further transmtted over the channel (guded or unguded. he data rate s dependent on the bandwdth further affected by the nose and sgnal strength. Let consder a model havng User A, multple ntermedate statons S, S... Sn and a recever (User B as shown n Fg.. Journal of Engneerng Scence and echnology August, Vol. 7(4

4 58 A. Kaar et al. Fg.. Mult-Node Networ Havng Varous Nodes Encrypted wth Varable Keys. If K users transmttng the data (bnary smultaneously n a common band wth a centre frequency f c, then the transmtted sgnal from the K th user s: s ( c t = Pb ( t a ( tcos(π f t + θ ( where P s the total power avalable to each user, b (t s the data sgnal of the th user, whch conssts of a rectangular pulse n the nterval of (rt, (r+. he n th bt, b,n n the K th user s assumed to be ± wth equal probablty and ndependent of all the bts, b,. hen we can wrte the data sgnal for the K th user: r = b ( t = b, p( t rt ( p( t =, = r t otherwse he sgnal a s the perodc coded rectangular pulse havng second duraton. It s used to spread to the data sgnal b. he recever for K th user of staton S receves the sgnal L M r ( t = P β ( t τ a ( t τ (3 b q= = q q q q ( t τ cos(πf t + φ n ( t (4 q q c q + where θ s the carrer phase unformly spread over random varable (, π. In ths paper a number of parameters are consdered... Number of users It s an mportant parameter; system s desgned on the bass of user. All the equpments and the accessores are nstalled by eepng an eye on the total number of users. Normally, a rough estmate s taen about the user, after that t s taen care that that grade of servce not fall below then 73% [,]. If model contans n number of statons; each capable of supportng x number of users then Journal of Engneerng Scence and echnology August, Vol. 7(4

5 Secure Communcaton n a Real tme Envronment for Multple Statons 59 the total number of users n a model s calculated as U N = n x. he effcency of the system s degraded by the faulty user. hey smply waste the bandwdth and create an overburden on the other staton (retransmsson of data, re-encrypton, generaton of ey(s [3, 4]... ype of Software/Hardware It provdes the faclty to the users to select/generate ther own ey(s. It s also used to determne the speed of the model. he length of a ey, n bts, for a conventonal encrypton algorthm s a common measure of securty. o attac an algorthm wth n-bt ey t wll generally requre roughly n- operatons. Hence, to secure a publc ey system one would generally want to use parameters that requre at least n- operatons to attac [5]. able gves the ey szes used n the proposed algorthm whch s the combnaton of DES and the Round Functon based on contans ECB (Electronc Code Boo, CBC, wth Cloc Speed:.4GHz, RAM: GB. able. Comparson of Performance of Measurng Parameters at Varous Statons. Operaton Statons 4 Statons 8 Statons 6 Statons 3 Encrypt me (s 8 bts Decrypt me (s 8 bts Key Setup me (s Algorthm Setup me (s Key Change 8 Based upon Based upon Based upon falure rate falure rate falure rate Run me (s Channel Capacty It s the capacty of the channel that how much data can be handled by the channel. he sgnal to nose rato s an mportant parameter n the transmsson of dgtal data. Channel capacty s determned by usng Shannon s theorem C = B log ( + S / N [6]. In deal case the channel bandwdth C = B. In order to ncrease the data rate ether sgnal strength or bandwdth s ncreased. When sgnal strength s ncreased t leads to nonlneartes (nter-modulaton nose whch mae the system unstable [7]. On the other hand ncrease n the bandwdth decreases the sgnal to nose rato [8, 9]. We focused on a new parameter, rato of energy per bt to nose power densty/hertz. Energy/bt n a sgnal are E b = S b. Where C and B are capacty and bandwdth of the channel respectvely, S s the sgnal power, b s the tme requred to transmt bt. hen the data rate can wrtten as R=/ b. herefore Bt Error Rate (BER wth respect to E b /N o can be determned n order to now the performance of the model. For Channel = AWGN, Modulaton order, 8, 6, for Modulaton type = DPSK (Fg. and for Modulaton type = PSK (Fg. 3. Journal of Engneerng Scence and echnology August, Vol. 7(4

6 5 A. Kaar et al. he results have been obtaned for and 9% confdence level. From Fgs. and 3 t has been observed that t s worthy to use PSK wth modulaton order 8 for a relable transmsson. Fg.. Performance of Proposed Model n AWGN Channel wth DPSK. Fg. 3. Performance of Proposed Model n AWGN Channel wth PSK..4. Falures occurred durng the nstallaton and transmsson he falures occurred durng the nstallaton and transmsson needs to be evaluated for a secured model. Durng the nstallng operaton t s observed that - 35% machnes fals, and after runnng the recovery mechansm t can be reduced to approxmately %.he falure of staton s tme dependent process [5, -]. For a model havng n number of dentcal statons the probablty of falure rate of statons can be determned as s = P ( ( e dt ( ( S = / where s.5a. he result holds good when sngle staton fals. For a huge model contanng large number of nodes the quantty A s too less than unty. herefore n that case falure of anyone staton can be gnored and the data s passed over the other path. On the other hand for the multple falures the ont probabltes are to be determned. Journal of Engneerng Scence and echnology August, Vol. 7(4

7 Secure Communcaton n a Real tme Envronment for Multple Statons 5 Case: Analyss of sngle ey havng same falure rate he case of same falure rate, a, ey,, and dentcal statons, S, where N, has been used to encrypt the data for the varous nodes present n the model. Each node encrypts the data wth sngle ey (dfferent for node,,..., N but havng same bt length. = P ( K = (/ ( e dt ( a a + e = P( K = ( / ( e dt = (3 a 3 x x By usng the expanson of e x = x , let x=a and from! 3! Eqs. ( and (3 we get: ( a ( a 3 a + a a a + e! 3! = a a 3 ( a ( a ( a ( a = +... = +... a! 3! 3 ( So, n the above expresson we neglect the hgher terms,.e., = a (4 we get a, whch s approxmately equals to.5a. Case: Analyss of sngle ey havng dfferent falure rate For dfferent falure rates, (a and b eys,, where N, has been used to encrypt the data for the varous nodes present n the model. Each node encrypts the data wth sngle ey havng dfferent ey lengths. = P( K = ( / ( e ( e dt = b ( b e b + ( e a ( t + (5 Case: 3 Analyss of multple (two eys havng same falure rate For dfferent falure rates, (a and b eys, and, where N, have been used to encrypt the data for the varous nodes present n the model. Each node encrypts the data wth eys havng same ey length., = P K K = (/ ( e.( e = P( K K ( dt (6 = e t at dt + e at dt = + a a a ( e ( e a Journal of Engneerng Scence and echnology August, Vol. 7(4

8 5 A. Kaar et al. a a a + 4e e 3 = a Agan by usng the expanson of ( a x e, t can be shown that: 3 (8 3 a whch s approxmately equals to.33(a. (7 Case: 4 Analyss of multple ey havng dfferent falure rate For dfferent falure rates, (a and b eys, and, where N, have been used to encrypt the data for the varous nodes present n the model. Each node encrypts the data wth eys havng dfferent ey length.,,, = P( K, K, = (/ ( e ( e dt ( e ( e dt (9 By solvng the frst half part of Eq. (5,.e., = (/ ( e ( e dt hs has been done because the n the reamng part all the terms are same, only the lmts are changed,.e., to so, the calculaton for the frst part s gven below: = ( e = ( e = ( e ( e e t b b + e b d( e dt dt at ae e t b ( e b ae dt b + e b. dt dt b b b ( b e a = ( e + b b b b ( b e ( b e dt b b { e ( b e } dt a = ( e + ( e b b b ( e b a( t+ = + ( e ( b At ths pont smlarly one can determne the second term and gven as: b ( e b a( t+ = + ( e ( b Usng Eqs. (9, ( and ( we can wrte: Journal of Engneerng Scence and echnology August, Vol. 7(4

9 Secure Communcaton n a Real tme Envronment for Multple Statons 53 b b ( b e ( t+ ( b e a ( t+, = + ( + ( a,, e e ( b b By usng Eq. ( the response of a staton havng dfferent falure rates for varable tme ntervals ( t s shown n able. able. Falure Rate and Encrypton me for Varous Statons. Statons a B S.. 5,S,, S ,S,, S ,S,3,3 S ,S,4,4 S ,S,5,5 3. Algorthm he algorthm checs the nput data stream and then further ey generaton process has been used to desgn the multple eys by usng S- Boxes. he nput data streams are broadly classfed nto four categores named as; ( alphabets and ( numerc data. hs bnary data strng has been used for the random ey generaton process specfed by able 3. Once the ey has been generated then the encrypton s carred by usng the fxed and varable length ey. he varable length ey has been preferred due to less overheads and t also provde more secured model. he paddng overheads are very small n ths case. he falure rate of ey has been checed by usng mathematcal tools; f ey strength s wea then the re-encrypton has been done by usng nd ey whch has been generated by usng the same procedure as used for st ey. he requrement of nd ey s requred f there s a node falure or nput data sequence s very large. he ey strength s very hgh n case of hybrd data sequences because more combnatons are avalable for the eys generaton. Data ype Alphabets Number able 3. Specfcatons of Random Key generaton Process. Condtons Operaton performed by S-Boxes Round Functons (RF A > B A + B 8 RF are used f nput data A = B A B A < B A B A > B A + B stream s 6 bts, otherwse 6 RF are used 8 RF are used f nput data stream s 8 bts, otherwse 6 RF are used Journal of Engneerng Scence and echnology August, Vol. 7(4

10 54 A. Kaar et al. he encrypton tme depends upon the number and type of operatons used n S-boxes and ey(s. he Round Keys are derved from the Cpher Key by means of the ey schedule. hs conssts of two components: the Key Expanson and the Round Key Selecton. he total number of Round Key bts s equal to the bloc length multpled by the number of rounds plus. Encrypton and Decrypton tme s determned by usng equaton (4. Whereas transmsson s based on the n channel; latency tme = lk l S l, where, l S s the smallest value of M n = latency and M s the total number of messages. Some encrypton technques provde a vrtually unbreaable barrer to nformaton theft; others ust requre a determned attacer wth moderate resources to be broen. One way to compare technques on ths level s to estmate how much CPU tme would be requred on a machne of a gven processng speed to terate through all the possble eys to the encoded data. For example, let s tae a system havng a ey of length bt then t s sure that the hacer s able to brea the system after 35 attempts (maxmum, technque s called Frst level encrypton E. If the ey length s ncreased then hacer has to made more attempts for the tas, technque nown as Second level encrypton E. For hghly secure model Re- Encrypton E r s used where multple eys are used by each staton/sub-staton along wth S-Boxes then t wll be very dffcult tas for the hacer. he Synchronzaton me (S t has been very mportant because transmtter and recevers needs to be run the encrypton and decrypton algorthm at the same tme for optmzed and secured data transmsson. In publc ey cryptography every user that wants to send or receve secure electronc mal needs a vald ey par. In a networed envronment, the user mght need to use electronc mal from multple computers, all wth dfferent operatng systems. hs creates a need for some nd of ey sharng scheme. herefore t s requred to synchronze the speed of transmtter(s and recever(s. In Fg., t s necessary to match the transmttng speed of A wth the recevng speed of S and so on. Also requred to determne the other parameters such as tme delay, processng tme of ndvdual statons, bandwdth of channel, and number of collsons occurred durng the transmsson. Compresson technques are used to mae the system effectve for adhoc networs. If the cpher text s transmtted through the web then t should be compressed ether by usng Drect Cosne ransformaton (DC or by wavelet technque []. In ths JPEG compresson technque s used, where the mage s splt up nto 8 8 squares. Each square s transformed by usng DC results a mult dmensonal array of 63 coeffcents at the output. hen a quantzer rounds each of these coeffcents, whch s the requred compresson stage (where data s lost, small unmportant coeffcents are rounded to where as larger ones lose some of ther precson. hen array of streamlned coeffcents, are used further compressed (Huffman encodng may be used. At the recever secton decompresson and decrypton are done by an nverse DC and decrypton model [, 5]. Paddng s requred when the plantext and the ey length does not matches. Consder a bloc cpher wth a bloc sze of B bts. It s often the case that the length of the natural nput wll not be of multple of B bts. hen, two optons are possble: ( the user should detect the partal bloc and handle t accordngly, or ( the mplementaton should accept partal blocs and use a strategy to map t to Journal of Engneerng Scence and echnology August, Vol. 7(4

11 Secure Communcaton n a Real tme Envronment for Multple Statons 55 a full bloc before the cpherng translaton. Zero paddng or PKCS paddng can be used dependng upon the requrement []. he method bascally acts as overheads but t does not cost the overall model so much. In case of zero paddng the zeros are added automatcally as a result t does not tae much tme. Unform lengths are always preferred n order to acheve relable and optmzed results. If msmatch sequences are taen then t wll ncreases the probablty of error. Also the latency tme ncreases n such cases. So partal blocs are selected and processed by the paddng process to mae them of equal szes. able 4. Paddng echnques. Key Plantext Zero Paddng Encrypted Data Decrypted Data 4. Concluson and Future Scope Practcal systems are not easy to handle, sometmes they behave very awwardly, and whle desgnng a system we always have to mae a system by eepng an eye on the worst case. Desgn ssues are not easy to adopt, dependng upon the nature they are taen. he algorthm used n the paper shows that all the stages are mutually ndependent from each other, provdes the faclty to use compresson and re-encrypton technques. It s stll requred to reduce the tme avalable for the hacer to mae the system more relable. Same can be done by re-encryptng the data by another ey. he am s to develop an encrypton algorthm whch provdes multple eys generated from the data tself and must be upgraded automatcally. References. Zou, C.C.; Gao, L.; Gong, W.; and owsley, D. (3. Montorng and early warnng for nternet worms. Proceedngs of the th ACM Conference of Computer and Communcaton Securty, Zou, C.C.; Gong, W.; and owsley, D. (. Code red worm propagaton modelng and analyss. Proceedngs of 9 th ACM Conference of Computer and Communcaton Securty, Deng, J.; and Han, S. (8. Multpath ey establshment for wreless sensor networs usng ust-enough redundancy transmsson. IEEE ransactons on Dependable and Secure Computng, 5(3, Chen, H.-Y. (4. Effcent tme-bound herarchcal ey assgnment scheme. IEEE ransactons on Knowledge and Data Engneerng, 6(, Journal of Engneerng Scence and echnology August, Vol. 7(4

12 56 A. Kaar et al. 5. Mhatre, V.P.; Rosenberge, C.; Kofman, D.; Mazumdar, R.; and Shroff, N. (5. A mnmum cost heterogeneous sensor networ wth a lfetme constrant. IEEE ransactons on Moble Computng, 4(, Ross, S. (9965. Stochastc Processes, ( nd Ed., John Wley & Sons. 7. Vauro, J.K. (. reatment of general dependences n system fault-tree and rs analyss. IEEE ransactons on Relablty, 5(3, zeng, W.G. (. A tme-bound cryptographc ey assgnment scheme for access control n a herarchy. IEEE ransactons on Knowledge and Data Engneerng, 4(, Y, X. (5. Securty of Chen s effcent tme-bound herarchcal ey assgnment scheme. IEEE ransactons on Knowledge and Data Engneerng, 7(9, Prasad, M.K.; and Lee, Y.H. (994. Stac flters and selecton probabltes. IEEE ransactons on Sgnal Processng, 4(, Amar, S.V.; Dugan, J.B.; and Msra, R.B. (993. A separable method for ncorporatng mperfect fault-coverage nto combnatoral models. IEEE ransactons. Relablty, 48 (3, Lngqun, W; Yngpng, Z.; and Shu, Z. (5. Applcaton of data mnng and data protecton n medcne. Computer Engneerng, 3(, Journal of Engneerng Scence and echnology August, Vol. 7(4