In this paper, we propose an authenticated data transmission technique for Clustered wireless sensor network (CWSN). The proposed scheme starts by assigning the identity, shared secret key and an encryption key to the sensor nodes by the base station (BS). Driven by the technology advances in micro-electronics, it is possible to run some key management techniques at each sensor level. This step helps in authentication of the sensors and secured communication in the network. Subsequently the sensor nodes are deployed in the hostile environments, due to the self healing nature of the sensors, they will form a network to transmit the data. The secured communicating protocol described in this paper guarantees that, when two sensor nodes are in communication, they must have gone through prior authentication and key pre-distribution process. The proposed scheme is invariant to the environment where the clusters are formed dynamically and periodically. According to the message communication point of view, we are restricting the network from receiving junk message from the adversaries or compromised nodes due to the authentication and confidentiality.