A Secure Mobile DRM System Based on Cloud Architecture

Transcription

1 Compter Science and Information Sytem 11(3): DOI: /CSIS C A Secre Mobile DRM Sytem Baed on Clod Architectre Chin-Ling Chen 1, Woei-Jinn Tar 2, Y-Yi Chen 3 and Yao-Chng Chang 1 1 Department of Compter Science and Information Engineering Chaoyang Univerity of Technology, Taichng, 41349, Taiwan {[email protected]; [email protected]} 2 Department of Information Management Da-Yeh Univerity, Changha, 51591, Taiwan [email protected] 3 Department of Management Information ytem National Chng Hing Univerity, Taichng, 402, Taiwan [email protected] Abtract. Pblic clod architectre offer a pblic acce oftware ervice. Uer can login to acce the clod reorce via vario device. The main advantage of the SaaS (Software a a Service) clod ervice i that it pport different oftware and device, in order to open web brower, to athenticate the er throgh the tandard format. E-book are protected by digital right management (DRM), and er can e mobile device to read them. However, the er' identity need to be athenticated or the commnication between the er and the clod erver will be at rik. The procee by which er bmit their proof of identity to the clod need to be protected. In thi paper, information ecrity can be achieved efficiently via clod erver architectre and a cryptography mechanim. The propoed cheme foce on ing a mobile device to acce the clod ervice. The DRM mechanim can protect digital content; once the mobile er pa the athentication they can acce the clod ervice, with athenticated er able to eaily e mobile device to read digital content. Keyword: Clod, DRM, Athentication, Mobile Device, Secrity 1. Introdction Firt, we introdce clod architectre, the DRM concept of clod architectre, and the analyi of DRM implementation ing mobile device. 1.1 Clod Architectre A long a information i tored in a clod, er can acce the clod ervice throgh the Internet and mobile device[1,2] anytime and anywhere. The er doe not need to

2 926 Chin-Ling Chen et al. know what kind of clod architectre i preent (ch a clter compting, grid compting, ditribtion compting, etc). The er need only end the reqet to the clod and it will perform the mot efficient operation. The early goal of clod architectre were to combine many compter of ditribted comptation via the Internet. The rnning program wa divided into many thread and ditribted into many compter for exection, with the relt being preented immediately. Clod architectre wa gradally developed into ervice-oriented application, with er being able to e the clod propertie: permanently available, fat compting, etc, with imple tep ch that er cold acce the ervice provided by the clod [3]. In the early tage, er commnicated with different device provided by the clod architectre, and the clod trctre commnication ervice needed to be robt. Crrent clod trctre ha adopted a hierarchical trctre. The top of the er ervice reqet meage i forwarded and handled by the internal framework. Uer do not directly commnicate with the internal trctre of clod, and thi enre internal afety; thi i called object-to-object architectre [3], and i ditinct from the early hotto-hot architectre. The preent clod trctre can be divided into the following three mode [4,5]; the trctre i hown in Figre 1. Pblic Clod Private Clod Hybrid Clod When the er reqet meage pae throgh the interface of a pblic clod, malicio packet are filtered ot by the firewall. The athenticated er reqet will be forwarded to the API erver. The API erver need not be in the ame geographical region. For example, when a Google Doc file i tored in a US databae, the docment can be opened by other people to co-edit it, and other er may edit the ame docment in different contrie; however, all of them e the ervice throgh the ame API. On the other hand, a private clod i an internal elf-management ytem databae which develop and maintain the normal operation of the API. The network i connected throgh a local network; thi incr greater cot for mall and medim enterprie. Th, the Hybrid Clod wa developed. The Hybrid Clod trctre act a a proxy erver in mot enterprie. It main goal i to identify taff identification. In thi way, it allow enterprie to control their own taff permiion, while the databae i maintained by the provider. Cot are there by redced. 1.2 Clod Service Model If clod ervice are provided by a ingle indtry, the clod may not be able to atify all of a er reqirement. Th, a er may e clod network ervice provided by different indtrie. Clod ize can be divided into the following mode: Dometic clod and Tranborder clod [6].

3 A Secre Mobile DRM Sytem Baed on Clod Architectre 927 Fig. 1. Clod architectre (1) Dometic clod: The entire clod i phyically located within one jridiction. The provider provide device or data exclively for pecific enterprie. The provider need not provide additional ervice via third party provider to a pecific provider, with the reltant advantage of niform ize and high data ecrity. (2) Tranborder clod: Device can tranmit data to a erver (ch a Google). Althogh the Google erver may be located in different contrie, er can determine which erver tore the data, even if they cannot find ome data. Google Doc i a imilar concept: omeone can open a file and other people can edit the ame docment in different location in different contrie. In Febrary 2000, Amazon.com ffered from DDOS attack which caed erio damage [7]. A new technology wa developed to defend againt ch attack. Now, packet will be filtered, and it will be determined whether they are normal or not by the firewall before er commnicate with the clod. The private key of the clod ytem i not tored in the er eqipment. The er mt e a ecre encryption method (ch a Pblic Key Infratrctre (PKI) or Secre Socket Layer (SSL) to tranmit meage to the clod, and then the clod tored er identity verification table will identify the er.

4 928 Chin-Ling Chen et al. In 2007, vendor phed the OpenID [8] verification pecification 2.0 and attribte of a tandard 1.0. OpenID, aiming to provide different clod provider with a mean to athenticate er identitie. The er only need to regiter once with OpenID, and they can then log into the athentication page. However, OpenID alliance hold enre the er afety and be able to determine if a clod i illegal or not, otherwie er privacy will be eaily revealed by a malicio attacker maqerading a a clod ervice. Clod ervice have been a hot topic in recent year. Depite the lack of a concrete definition of a clod, there eem to be a common conen a to what contitte a clod [6]. The National Intitte of Standard and Technology (NIST) [9] ha propoed the following five baic characteritic of crrent clod architectre: (1) On-demand elf-ervice: A conmer can nilaterally provide compting capabilitie, ch a erver time and network torage, a needed atomatically, withot reqiring hman interaction with each ervice provider. (2) Broad network acce: Capabilitie are available over the network and accee throgh tandard mechanim that promote e by heterogeneo thin or thick client platform (e.g., mobile phone, laptop and PDA). (3) Reorce pooling: The provider compting reorce are pooled to erve mltiple conmer ing a mlti-tenant model, with different phyical and virtal reorce dynamically aigned and reaigned according to conmer demand. There i a ene of location independence in that the ctomer generally ha no control over or knowledge regarding the exact location of the provided reorce, bt may be able to pecify location at a higher level of abtraction (e.g., contry, tate or data center). Example of reorce inclde: torage, proceing, memory, network bandwidth, and virtal machine. (4) Rapid elaticity: Capabilitie can be rapidly and elatically proviioned, in ome cae atomatically, to qickly cale ot, and rapidly releaed to qickly cale in. To the conmer, the capabilitie available for proviioning often appear to be nlimited and can be prchaed in any qantity at any time. (5) Meared Service: Clod ytem atomatically control and optimize reorce e by leveraging a metering capability at ome level of abtraction appropriate to the type of ervice (e.g., torage, proceing, bandwidth, and active er accont). Reorce age can be monitored, controlled and reported, providing tranparency for both the provider and conmer of the tilized ervice. A long a a ervice i connected to a network and e the network to achieve a certain goal, it can be called a clod ervice (for example: , E-book, Google Doc, Google TV, Clod Printer, etc). That i, er rely on the application data tored on a remote erver, with no additional device intalled in the peronal application. Uer data and information can be tored anywhere in the clod. A prereqiite of connecting to the clod i network connectivity. Uer can end a meage, e the ervice, receive meage etc; all rely on a network connection to commnicate with the clod. The er information mt be protected o there mt be commnication throgh a mechanim to protect the er identity and information. Different pplier have different protection mechanim, for example, Google protection mechanim i ed for SSL. The remainder of thi paper i organized a follow: Section 2 review the DRM related work. In ection 3, we introdce the propoed protocol. Section 4, we analyze the ecrity of the propoed cheme, and we provide conclion in Section 5.

5 2. The DRM Related Work A Secre Mobile DRM Sytem Baed on Clod Architectre 929 E-book are crrently the main prodct of clod ervice. At preent, the main provider are companie like Google, Apple, and Microoft, althogh the E-book format ha yet to be tandardized. However, the main pecification of E-book are DRM, DRM-Free, and Adobe PDF format. Take, for example, DRM-Free with permiion [10]; on April 2, 2007, Apple annonced that half of the DRM-protected mic on itne wold be old via DRM- Free. The price wold be lower for higher mic qality. In thi way, DRM-protected MP3 digital prodct it needed to pay for the licene; there wa the limitation that only Apple-related prodct cold hare thi benefit. On the other hand, Google DRM-Free forbid er to copy or print the digital content [11]. The primary bine objective of DRM are: Provider mt pecify the er right Digital content cannot be tampered The print and copy permiion of the digital content need to be athorized Digital content Copyright notice The Provider ell DRM-protected digital content that can be ed to control the conmer right [12, 13, 14, 15]. However, the DRM clod provider athorize the er to acce the digital content via a one-time ale. Microoft for digital content protection [16] mt intall the RMS oftware at the er end, and i limited to Window OSe. The encryption method i the RSA [17] key component. When a er reqet to athorize the e of a right, it allow the deignated er and i athorized to grant the permiion. However, the SP2 verion added an offline athorization fnction, and athor e the RMS application to create file permiion; thi pecifie the athorization condition. Thi i a pecial licene which can be granted by the offline tate RMS-protected content permiion. Or propoed architectre allow conmer to download E-book and enjoy the benefit of the trial period (e.g., DRM-Free). When er by the prodct, the er permiion will be changed via Licene (ch a DRM). However, or architectre i ch that, via the Internet, it i poible at any time to record a er E-book page nmber. The advantage of or approach are that it allow er to read E-book on different device, and it can be eaily modified to record the nmber of page. It can alo prevent prchaed E-book er illegally forwarding docment to other er. 2.1 Dicion of Uing a Mobile Device to Implement DRM With the rapid development of mart mobile device, it i now poible to eaily acce network reorce. Even thogh it i well-known that mobile device are ndermined by everal recent threat [18], thee mobile device (ch a PDA or Tablet PC) and clod ervice can be combined to form an eay to e commnication platform.

6 930 Chin-Ling Chen et al. Uer can acce the clod ervice throgh different mobile device, however, the hardware of ch mobile device i limited in the following way [7, 19]: bandwidth limitation connection tability low comptational ability limited battery capacity mall torage capacity From the mobile er viewpoint, the er mt provide hi/her identification before ing the clod ervice. Thi i different from ing a mart card, ince not every device can read mart card. Moreover, different operating ytem have different peripheral limitation (ch a ipad). Althogh er can browe the web, the device doe not provide a general tandard interface (ch a USB) to provide the mart card reading fnction or other more ecre mechanim (ch a a biometric identification mechanim). On the other hand, the mobile device compting power i limited. In order to end a protected meage from thee mobile device it i neceary to conider other appropriate ecrity mechanim. Google or Apple, and other provider of thee clod ervice, do not provide a clear definition for the ervice model of the clod. In thi paper, we preent a mobile device-baed DRM ytem to achieve the following objective: (1) Provide a proce for clearer commnication enabling a nified athentication. (2) Redce the comptation of commnication for mobile device. (3) The pplier can e their encryption method to protect the ecrity of E-book. (4) The E-book provider for DRM prpoe of ale and limitation are not the ame. In order to achieve the reqired level of ecrity, we have integrated the mobile device and the clod ervice model to allow er to acce an E-book reorce nder ecre athentication. 3. Propoed Athentication Protocol Becae Linx i ottanding for parallel compting and execting efficiency [4], the propoed clod ervice for mobile DRM ytem i baed on Linx. Linx i open orce, o er can develop vario API to meet their reqirement. The er meage will firt pa throgh the firewall to confirm whether or not the packet are normal. For athenticating er, the clod erver aim to prodce the eion key between er and clod. The clod confirm the identity of the er mobile device. The er need not worry abot the meage ent to the clod end or the internal proceing. Or propoed architectre i hown in Figre 2:

7 A Secre Mobile DRM Sytem Baed on Clod Architectre 931 Fig. 2. Or propoed architectre Step 1: Uer log into clod for athentication via mobile device. Step 2: Clod confirm the er identification and generate the eion key. Step 3: The er' meage i protected by the eion key and a ervice reqet i made to the clod. Step 4: Clod repond to er reqet (ch a the E-book page or E-book age right). Or cheme i to record the page nmber of the er lat review. We limit the er commnication time with the clod to negotiate the eion key by changing the licene permiion. The advantage are that er can read E-book on different device, and we can prevent acce to the E-book. The following notation i ed in thi paper: exclive -or operation : concatenation operation ID : er identification PW : er paword IMEI : identity of the mobile device, International Mobile Eqipment Identification N, N : nonce SK : eion key between er and clod E book req : mobile er firt reqet of the E-book M req : E-book page nmber reqet after lat view RESP : repone meage of the clod to er reqet E SK (m) : e the ymmetrical key SK to encrypt a meage m D SK (m) : e the ymmetrical key SK to decrypt a meage m A? B : determine whether or not A and B are eqal h (.) : one way hah fnction

8 932 Chin-Ling Chen et al. 3.1 Regitration Phae The er propoe an identification ID and paword pw to the clod throgh a ecre channel. The clod tore the er athentication information in the verification table. 3.2 Athentication Phae The er athenticate with the clod, and generate a eion key. Figre 3 how or propoed athentication protocol. Step 1: Uer enter ID and pw, and generate a nonce follow: N and comptec1 and C 2 a C IMEI ) 1 N (1) Afterward, the er end (ID, IMEI, C 1 and C 2 ) to the clod. Step 2: The clod firt check ID and e the ID to identify the correponding pw on the verification table. Then the clod compte N and perform the athentication a Eq. (4) C ID N IMEI )) (2) 2 N C pw ) IMEI ) 1 (3) ID pw ) N IMEI ))? C (4) If Eq. (4) hold, then the clod complete the er athentication. The clod generate N and compte the commnication eion key for the next commnication a follow: 2 SK N N ) IMEI (5) Afterward, the clod end IMEI N ) N and h IMEI N N ) to the er. Step 3: The er compte N and check N ( N IMEI N ) IMEI N ) N (6) IMEI N N? IMEI N N ) (7) )

9 A Secre Mobile DRM Sytem Baed on Clod Architectre 933 Fig. 3. The overview of or propoed athentication phae If Eq. (7) hold, the clod complete the mtal athentication with the er, and then the er can commnicate the ervice meage with the clod. The er alo generate a eion key SK for the next commnication. SK N N ) IMEI (8) 3.3 Service Repone Phae The er preent the ervice reqet by ing the previo generated eion key, and the clod repond to the er reqet. Figre 4 how or propoed ervice repone proce.

10 934 Chin-Ling Chen et al. Step 1: The er chooe the clod ervice API licene or ak to repond to the reqet; the clod athenticate the er identity, generating a ymmetric encryption meage a follow: C E ( E book ) (9) 3 SK req or C E ( M ) SK (10) 3 req A new nonce N i generated and an athentication meage i compted a 1 follow: C (11) IMEI ) N 4 1 C ID N IMEI )) 5 1 (12) Afterward, the er end ID, C, C, ) to the clod. ( C Step 2: The clod firt check ID, and e the correponding eion key SK to decrypt the ervice reqet. The clod compte N 1 N E book D ( C 3 ) (13) req SK or M D C ) (14) req ( SK 3 C pw ) IMEI ) 1 4 (15) ID pw ) N C (16) IMEI ))? 1 5 If Eq. (16) hold, then the clod generate the next nonce N, and calclate the 1 new eion key SK a follow: new SK new N N ) IMEI 1 1 (17) Uer compte C a follow: 6 C E ( RESP) 6 SK (18) n ew Afterward, the clod end C, 6 h ( h ( pw ) IMEI N ) N 1 and h ( IMEI N ) 1 N to 1 1 the er.

11 A Secre Mobile DRM Sytem Baed on Clod Architectre 935 Fig. 4. The overview of or propoed ervice repone phae Step 3: The er compte N 1 a follow: N (19) IMEI N ) IMEI N ) N And athenticate the N 1 ) IMEI N N? IMEI N N ) (20)

12 936 Chin-Ling Chen et al. If Eq. (20) hold, then the er e the previoly generated N to compte the 1 SK a follow: new SK new N N ) IMEI 1 1 (21) and decrypt C to obtain the repone meage RESP 6 RESP D ( C 6 ) (22) SK n ew Th, the er can acce the previoly reqeted meage RESP. In or propoed protocol, the clod ervice er can contine to maintain a ecre commnication with the clod. 4. Secrity Analyi The following analyi i to how how or propoed cheme can prevent vario attack. 4.1 DOS Attack Prevention A with the Amazon clod infratrctre ite [5], the er commnication meage are the firt throgh the firewall filter on the erver. The er can ynchronize with cookie to redce abnormal malicio attack, and er alo mt be limited to connect with the clod. If er e the brower to perform malicio attack, the erver atomatically lock the er behavior. For example, if the ame IP reqet 1000 meage in one econd, the er i regarded a a malicio attacker, and the erver will block the IP ervice. 4.2 Paword Geing Attack Prevention A the er do not tore any er data in their mobile device, an attacker cannot achieve offline paword geing attack via the mobile device. The clod protect the er accont on the clod end. If an attacker or a legitimate er enter conective incorrect paword, the erver will block the accont, and the er will be reqeted to change the paword and to end the regitration information via . Th, there i no way to e online paword geing attack ince the attacker or the er doe not know the previo paword et. 4.3 Inider Attack Prevention High vale aet of the clod ytem [5] reqet the er to change their paword reglarly, and the private key of the erver will alo be reglarly changed. While the clod tore the paword, it doe not directly tore er paword, and it i protected

13 A Secre Mobile DRM Sytem Baed on Clod Architectre 937 by a one way hah fnction in order for er to tore their paword. For example, a er paword pw and Linx private key x are protected by an MD5 hah fnction x)). So, even if an inider attacker (root) teal the verification table, the attacker cannot e brte-force attack to ge the er paword and identify the erver private key. 4.4 Reply Attack Prevention Becae the nonce N and N are not the ame, even if the attacker were to intercept the meage ( C IMEI ) N and IMEI N 1 ) N ), in order to make a forged meage C IMEI ) N 4 1 h ( IMEI N ) N ) 1 1, an attacker cannot e the intercepted meage to commnicate with a er on the clod dring the athentication phae. and 4.5 Imperonation Attack Prevention Since each commnication i recorded for a er ID and IMEI, the er paword pw i protected by a one way hah fnction ( C IMEI ) N ), o the 1 attacker cannot cceflly fake being the er dring the commnication proce. Neither can an attacker fake being the erver. Moreover, the er' paword i difficlt to work ot. Only the legal clod can compte the correct N C pw ) IMEI ), o the attacker cannot fake being the clod Man-in-the-Middle Attack Prevention Each meage i protected by two nknown nonce N and h (, o even if an X attacker intercept the meage C IMEI ) N and 1 IMEI N ) N, the attacker cannot pa the athentication by the following eqation: ID pw ) N IMEI ))? C 1 2 and h IMEI N N )? IMEI N N ). Th, the Man-in-the-Middle attack will be prevented. ( 4.7 Parallel Seion Attack Prevention The er tranmit the commnication meage C, C, C, ) to the clod, and the ( C clod repond with the meage IMEI N ) N and h IMEI N N ). Both (

14 938 Chin-Ling Chen et al. of the commnication meage of the hah vale are different; th, the propoed cheme prevent parallel eion attack. 4.8 Seion Key Error or Tampering Or protocol aim at redcing the comptation cot on the mobile device. Once the eion key i checked, if an error occr or the key i tampered with dring the athentication, the er jt need to be athenticated again and log into the clod to acce the clod ervice. 4.9 Comparion From Figre 5, it can be een that we combine the charging mechanim and replace age right with licene in order to change the method of E-book age right via prchae. The propoed cheme enable the clod to eaily record a er reading information, and the lat viewed page immediately, depite interface and device limitation. Uer can read E-book free from the vario device and paid oftware (ch a office erie) limitation anytime and anywhere. We e ymmetric encryption for the device to redce the comptation and commnication cot, which i different from other pplier encryption mechanim. Fig. 5. The comparion of the related work 5. Conclion The propoed clod cheme not only provide more convenient E-book ervice, bt allow er to apply to other clod ervice, with the digital content tored in the clod. Uer can acce E-book ing different device, anytime and anywhere. The digital content i protected by DRM, which i flexible via changing the licene age mechanim ch that the clod can record the er information. Or propoed protocol allow er to e different mobile device to acce the clod ervice. The mobile device do not need to tore the er privacy and clod related meage. In the commnication proce, we e low complexity fnction (ch

15 A Secre Mobile DRM Sytem Baed on Clod Architectre 939 a hah fnction, exclive-or and lightweight operation [20, 21]) to redce the compting cot of the mobile device, and we alo addre mtal athentication ie. Thi tdy realize the following goal: (1) Propoe a cro-vendor athentication of the clod. (2) Reit known attack. (3) Provide a low compting cot for mobile er. (4) Provide a er friendly e for the digital content. (5) Provide a device-independent management for DRM. Conidering the ditribted natre of protected DRM content and alo that the propoed protocol allow to e different mobile device, ome poible ftre work cold be to extend the work in a way to be alo applicable to interconnected federated clod, ch a propoed in [22]. Reference 1. Albano, P., Brno, A., Carpentieri, B., Catiglione, A., Catiglione, A., Palmieri, F., Pizzolante, R. and Yo, I.: A Secre Ditribted Video Srveillance Sytem Baed on Portable Device, Lectre Note in Compter Science, Vol. 7465, pp , (2012). 2. Pizzolante, R., Carpentieri, B. and Catiglione, A.: Text Compreion and Encryption throgh Smart Device for Mobile Commnication, Proceeding of 2013 Seventh International Conference on Innovative Mobile and Internet Service in Ubiqito Compting (IMIS 2013), Jly 3-rd to Jly 5-th, 2013, Aia Univerity, Taichng, Taiwan, pp Ohlman, B., Erikon, A., Rembarz, R.: What Networking of information Can Do for Clod Compting. the 18th IEEE International Workhop on Enabling Technologie : Infratrctre for Collaborative Enterprie, 78-83, (2009). 4. Byya, R., Yeo, C.S., Vengopal, S., Broberg, J., Brandic, I.: Clod Compting and Emerging IT Platfom: Viion, Hype, and Reality for Delivering Compting a the 5th Utility. Ftre Generation Compter Sytem, Vol. 25, No. 6, , (2009). 5. Sbahini, S., Kavitha, V.: A Srvey on Secrity Ie in Service Delivery Model of Clod Compting. Jornal of Network and Compter Application, Vol. 34, No. 1, 1-11, (2011). 6. Svanteon, D., Clarke, R.: Privacy and Conmer Rik in Clod Compting. Compter Law & Secrity Review, Vol. 26, , (2010). 7. Chen, C.L.: A Secre and Traceable E-DRM Sytem Baed on Mobile Device. Expert Sytem With Application, Vol. 35, No. 3, , (2008) 8. OpenID. Acce available 13/8/ Mell, P., Grance, T.: The NIST Definition of Clod Compting (Draft). Acce available 4/8/2011, (2011). 10. Apple DRM-Free. Acce available 13/8/ Google DRM-Free , Acce available 13/8/ Google DRM. Acce available 13/8/ Google adopt Adobe ebook DRM. google-ebook.html, Acce available 13/8/2013.

16 940 Chin-Ling Chen et al. 14. Chen, Y.Y., Wang, Y.J. and Chen, J.C.: A Fair-e DRM Sytem Baed on Web Service. Eighth International Conference on Intelligent Sytem Deign and Application, Vol. 3, No. 11, 11-16, (2008). 15. Lee, W. B., W, W. J., Chang C. Y.: A Portable DRM Scheme Uing Smart Card. Jornal of Organizational Compting and Electronic Commerce, Vol. 17, No. 3, , (2007). 16. Window Right Management Service Acce available 13/8/ Rivet, R., Shamir, A., Adleman, L.: A Method for Obtaining Digital Signatre and Pblic Key Cryptoytem. Commnication of the ACM, Vol. 21, No. 2, , (1978). 18. Catiglione, A., De Prico, R. and De Santi, A.: Do Yo Trt Yor Phone?, Lectre Note in Compter Science, Vol. 5692, pp 50-61, (2009). 19. Chen, C.L.: All-In-One Mobile DRM Sytem Deign. International Jornal of Innovative Compting, Vol. 6, No. 3A, , (2010). 20. Chen, C. L., Tai, Y. T.: Aniello Catiglione and Franceco Palmieri, Uing Bivariate Polynomial to Deign a Dynamic Key Management Scheme for Wirele Senor Network. Compter Science and Information Sytem, Vol. 10, No. 2, , (2013). 21. Chen, C. L., Tai, W. C.: Uing a Stored-vale Card to Provide an Added-vale Service of Payment Protocol in VANET Seventh International Conference on Innovative Mobile and Internet Service in Ubiqito Compting (IMIS 2013), Jly 3-rd to Jly 5-th, 2013, Aia Univerity, Taichng, Taiwan. 22. Epoito, C., Ficco, M., Palmieri, F. and Catiglione A.: Interconnecting Federated Clod by Uing Pblih-Sbcribe Service, Clter Compting, In pre, DOI / z, (2013). Chin-Ling Chen, PhD, i a member of the Chinee Aociation for Information Secrity. From 1979 to 2005, he wa a enior engineer at the Chnghwa Telecom Co., Ltd. He i crrently a profeor of the Department of Compter Science and Information Engineering at Chaoyang Univerity of Technology, Taiwan. Hi reearch interet inclde cryptography, network ecrity and electronic commerce. Dr. Chen had pblihed over 50 SCI/SSCI article on the above reearch field in international jornal. Woei-Jinn Tar, PhD, worked a a project manager and technology conltant from 1994 to 2003 in R&D Diviion of Sycom Compter Engineering Co., a reearch center of oftware development in Taiwan. Since 1999, he ha been with the Department of Information Management at Da-Yeh Univerity, Taiwan, where he i crrently a fll profeor. Hi reearch interet inclde network ecrity, ecrity topic in operating ytem, applied cryptography, information ecrity management and compter network. He ha directed many reearch project in the area of network ecrity and clod compting ecrity. Dr. Tar i alo a member of the IEEE and the Chinee Cryptology and Information Secrity Aociation. Y-Yi Chen, PhD, i preently an aociate profeor of the Department of Management Information ytem, National Chng Hing Univerity, Taiwan. Hi reearch interet inclde compter cryptography, network ecrity, and e-commerce.

17 A Secre Mobile DRM Sytem Baed on Clod Architectre 941 Yao-Chang Chng wa born in He received the B.S degree in Department of Compter Science and Information Engineering from St. John' Univerity, Taipei Taiwan in He received hi Mater degree at the Department of Compter Science and Information Engineering, Chaoyang Univerity of Technology in Hi reearch interet inclde information ecrity and clod ecrity. Received: September 19, 2013; Accepted: Janary 6, 2014.

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