With benefit of ease and convenient deployment and maintenance, wireless sensor 

networks has evolved as a important technique and finds it application in various field such as environment monitoring, health monitoring,  crop monitoring, military surveillance etc.  The sensor node may be placed in unattended places and the transmission takes place in wireless medium. Hence the data is more vulnerable for the attacks. Secure transmission of data in wireless sensor network is an important requirement.  In an unattended network it is essential to ensure that data is from the valid user. User Authentication is a fundamental protection measure for a secure network system. This paper presents the analysis of various attacks and the security measurements needed to protect from the attack. In this paper a ticket based authentication is proposed in which the tickets are distributed priory.  Based on the ticket the client authenticate with base station. It uses simple operation for authentication hence the computational load for authenticity is less. The proposed scheme analyses the security measure and computational cost. In general the data are collected from the base station, to foresee the data there may be situation in which the data from the sensor nodes need to be collected. The provision to access the data from the sensor node by the third party should be granted. If third party is granted with access to the sensor data, then proper security and authentication for the user (third party) need to be provided. This paper describes a mutual authentication scheme for the user, sensor node and base station.