Due to advancement in E-commerce, M-Commerce and rapid development in wireless technology shift of users from wired network to wireless network have increased day by day. Since wireless networks are easy to break and prone to security threats, it is important that all wireless users are required to be authenticated before using the information present in the wireless LAN. Also doing secured online transaction in wireless LAN, authentication of user is the upmost requirement. Due to uniqueness of biometric traits it can be used in authentication. In this paper, we proposed a finger based biometric authentication scheme. During enrollment, minutia points are generated and encrypted using Gauss Iterated Map. The encrypted template is stored in the template database. During authentication, a matcher algorithm is used to match the minutia points of the decrypted thumb template of the particular user captured during enrollment with the minutia points generated during authentication. If match is found then server will generate a One Time Password (OTP) and send to the user for further level of authentication. If user enters the correct OTP through client interface to the server then ARAS (Advanced Remote Authentication Server) grants permission to access the system to that user otherwise access is denied to the user.