Proposal and Development of Encryption Key Distribution System Using Visible Light Communication

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Therefo a wireless LA uate managem d unauthorized yption key anges the encr nistrator and ght communic use VLC has a with radios and n area of VLC ight area recei nnot receive t ethod that di em using VLC ryption key of user . A proto LC is also the l be constant. T d. In the exper by USB bass p ise (Eb/N) and ured by the ch the relationsh e. The results istribution, an and secure wir le Light Co otspotI. I NTR between VLC a us ed VLCs (v LEDs has spr er power con bs and fluores d for lighting and D bution Murata, Tom Uemuraronics Inform University,Japanc.ryukoku.ac.j aru}@rins.ryuk eless LAN us lic wireless LA mission area of ore, it is diffic AN. As a resu ment against in d access. Adm frequently. H ryption key fr users. If the cation), it is a clear commu d IR (infrared C, thus it is eas ive the encrypt the encryption istributes encr C. The innovat a wireless LA type system is lighting system Therefore 2 P P riment, we use ower. The com d error rate w hanging illumin hip between t show that sys nd we are abl reless LAN. ommunication;RODUCTIONand LEDvis ible light c read because s umption and scent tubes. T and traffic s ig Develo n Syste Comm moo Nakamu matics, jpkoku.ac.jpsers is increa AN services is f a wireless LA cult to contro ult, administr nformation lea ministrators ne However, if requently, this administrator easy to co unication area.d rays), we ca sy to control ac tion key. The u key. In this p ryption keys tion of this pap AN using VLC s also evaluate m. The brightne PM (pulse pos e very bright L mmunication sp were measured.nation of the L the communic stem was usefu le to commun ; wireless L communicatio of their low p d longer life Therefore, they gnals [1, 2]. T opmen em Us municura,asing. s also AN is ol the rators kage, eed to the s is auses ontrol This n see ccess. user s paper in a per iswith ed. In ess of sition LEDs, peed, . 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How key frequently lic wireles sL fraredspeed cause uency sition f we hange nergy ess to ge theNefore,asing. ble to fficult r of gainst ccess. wever, y, it isLANs2011 IEEE International Conference on Consumer Electronics - Berlin (ICCE-Berlin)are t diffi encr adm anyo encr on a been encr man enha incoII T a wi the encr deliv light Ther the devi of thA. A In th by U This light DC rece The Theryen the low level icult for una ryption key minis trator. Ho one acces s it ryption key reg administrators n us ed witho rypted commu ny free s pots,anced, conven nvenient serv II. P ROPOSE his paper prop reless LAN sypropo s ed s y ryption key o vered by VLC ting, and wil refore, only th wireles s LAN ice. The lighti he transmissio F IV. About equipme he experiment USB bass pow s circuit has a t except VLC (direct curre iver are contronumber of tr re are 15 tran (U.S. $16). T security for c authorized us for a wirele owever, once . Therefore, gularly. Encry s and us ers. H ut us ing an unications are , which has nience is impa ices. ED E NCRYPTIO poses the distr ystem using V ystem. The l f the wireles s C. The users ta ll be able to he users in the N. In this pa ing must be of on data. Theref Figure 2. Over E XPERIMENT entt, we use very wer. The receiv simple high p has low-freq ent) compone olled by an AV rans mitter an ns mitter comp There are 24 re convenience. T ser s to u se e LAN i the encryptio it is neces s a yption key cha Hence s ome a encryption k e eas ily tappe safety probl aired, and user ON K EY DISTRI ribution of an VLC. Figure 2lighting s y s te s LAN. The ake the encryp o connect th e lighted area aper, the VLC f uniform brig fore, PPM is u rview of syste T AND E VALU y bright LEDs ver element is pass filter, bec quency noise, ent nois e. Th VR micro com nd receiver co ponents , which eceiver compo Therefore iti the service.provided by on key is kn ary to change anges are a bu acces s points key s et, and ed. There are lems . If s afet rs do not often IBUTION S YST n encryption k 2 is an overvie em superimp encryption ke ption key from he wireles L will be able to C is als o ligh ghtness, regar used [1, 2]. emUATION, which are dr s a phototrans cause illumin and sunlight h he transmitter mputer (Ardui omponents is h cos t about onents, which s not An y the nown, e the urden have non-such ty is n use TEM key inew of posed ey is m the LAN. o use hting rdlessriven istor. ation has a andino). low.1300 h costabou are vB. SThe gene AVR the mod tran elec the c wire C. TThe 1170Whe bits comut 2200 yen (very low cost F Signal flowFigurs ignal flow erates an encr R micro com received en dulated light i sistor. The trical s ignal. client comput eless LAN, us Throughput oretically, the 0 micro-secon en s uperimpo to be tranmmunication sp (U.S. $27). Th to make.Figure 3. Photo re 4. Block dia is s hown in ryption key. T mputer. The A ncryption key s converted in AVR micro The demoduter, and the cli ing the encryp e time for 8 b nds, and the co os ed on the H n s mitted i s 1peed is 4.2 kb hus the transm o of experime agram of signa Figure 3. Th The encryption AVR micro co y and fla s he nto electrical o computer ulated encrypt ient computer ption key. bits (1 byte) to ommunication Hamming cod 1890 micro-sbps. mitter and rec ental flow e s erver com n key is sent t omputer modu sthe LED. signals by a p demodulates tion key is s e can connect t o be transmitt n speed is 6.8des , the time second s, and ceivermputer to the ulates The photo theent to to the ted is kbps. for 8d theD. Description of experimentThe distance between the LED and receiver was fixed at 1 m. The intens ity of the nois e lighting and VLC lighting weremeasured. We measured the error rate and Eb/N. One byte ofdata signals was transmitted, and the bit errors were counted. The error rate was then calculated.E. Experimental resultsFigure 5. Experimental resultsThe experimental results are shown in Figure 5. When EB/N is about 8, the signal strength of signal 1 was 110 lux and, Signal 2 was 80 lux. When Eb/N is less than 10, an error occurred at Signal 1. When Eb/N is less than 8, an error occurred at Signal 2. The caus e of the difference is not only Eb/N, but is probably related to the pure s ignal s trength. The optical signal s were converted into electrical signal s, and the electrical signals were converted from analog signals to digital signals by the comparator. Errors occur if the signal strength is below a certain level.Figure 6. Relationship between distance and angleThe angle of the tran s mitter and receiver affect s the communication distance. This can be understood from Figure6. From this res ult, only us ers in the light can receive the encryption key. This is related to the directivity of the LED and phototrans is tor. The LED and phototrans is tor are highly directional. Thu s by attaching a len sto the LED, the administrator can easily change the communication area.The transmission speed was around 2.4 kbps, with Hamming codes, and around 4 kbps without Hamming codes. We are not going to optimize our program. In this condition we can get the transfer rate of about 60% of theoretical maximum value.V.C ONCLUSIONThis s tudy examined an encryption key dis tribution s ys tem using VLC. The system can easily limit the users. By sending the light power used long-distance communication is possible in mos t cas es. The s ys tem is able to correct errors by us ing Hamming code. If AGC (auto gain control) is used, it will be able to communicate regardless of the distance. In the future, the modulation s cheme will be changed, and the optimal modulation methods evaluated. For the future we optimize our program.A CKNOWLEDGEMENTThis work was supported by KAKENHI 21710188.[1] T. Saito, S. Haruyama, and M. Nakagawa, “A Study for flicker onVisible Light Communication,” Technical Report of IEICE CS, vol. 106, No. 450, pp. 31-35, January 2007.[2] I. Shouichi, M. Nakagawa, and S. Haruyama, “Reduction of Flicker byCoding and Modulation for Vis ible-Light Communication” Technical Report of IEICE OCS, vol. 108, No. 39, pp. 1-4, May 2008.0.0000010.00010.0114681012E r r o r R a t eEb/N Signal1Signal2。