Information Technology Journal1812-56381812-5646Asian Network for Scientific Information10.3923/itj.2008.63.69Chou LiaoHsien- -Hsiang ChaoYun 1200871The wide spread of WLAN and the popularity of mobile devices increases the frequency of data transmission among mobile users. However, most of the data encryption technology is location-independent. An encrypted data can be decrypted anywhere. The encryption technology cannot restrict the location of data decryption. In order to meet the demand of mobile users in the future, a location-dependent approach, called Location-Dependent Data Encryption Algorithm (LDEA), is proposed in this study. A target latitude/longitude coordinate is determined firstly. The coordinate is incorporated with a random key for data encryption. The receiver can only decrypt the ciphertext when the coordinate acquired from GPS receiver is matched with the target coordinate. However, current GPS receiver is inaccuracy and inconsistent. The location of a mobile user is difficult to exactly match with the target coordinate. A Toleration Distance (TD) is also designed in LDEA to increase its practicality. The security analysis shows that the probability to break LDEA is almost impossible since the length of the random key is adjustable. A prototype is also implemented for experimental study. The results show that the ciphertext can only be decrypted under the restriction of TD. It illustrates that LDEA is effective and practical for data transmission in mobile environment.]]>Aikawa, M., K. Takaragi, S. Furuya and M. Sasamoto,1998Becker, C. and F. Durr,2005Eagle, N. and A. Pentland,2005Gruteser, M. and X. Liu,2004Jamil, T.,2004Jiang, J.,1996Lian, S., J. Sun, Z. Wang and Y. Dai,2004Liao, H.C., P.C. Lee, Y.H. Chao and C.L. Chen,2007McLoone, M. and J.V. McCanny,2000Mohapatra, D. and S.B. Suma,2005Mundt, T.,2005Qiu, D., S. Lo, P. Enge, D. Boneh and B. Peterson,2006Scott, L. and D.E. Denning,2003Shaar, M., M. Saeb, M. Elmessiery and U. Badwi,2003Smid, M.E. and D.K. Branstad,1988Toye, E., R. Sharp, A. Madhayapeddy and D. Scott,2005Xu, J., B. Zheng, W.C. Lee and D.L. Lee,2004Zhang, Y.P., J. Sun and X. Zhang,2004Zhang, Y., W. Liu, W. Lou and Y. Fang,2005