Abstract: Sensor network has quick installation, dynamic configuration features. Security of the data in the wireless sensor network has become a critical issue. As the applications are increasing, privacy preservation is an important issue in wireless sensor network. Depending on the nature of the installment of the network and the data that is exchanged between two nodes, steps taken to secure the data have to be decided. Security mechanisms like authentication and encryption play a vital role. The existing encryption algorithms cannot be applied directly to WSN. Care has to be taken to modify these algorithms to fit into WSN, as these modifications may lead to additional computations which consume additional energy and additional communication. This paper aims at implementing one such encryption algorithm which is easy to develop using common programming language like C and easy to port across different processors varying in processing speed, computations and operating word size.