Wireless sensor network research enriched with diverse applications from industry to daily life. Widespread of sensor-based applications mandated for user authentication and secure communication. However, sensor nodes are limited energy and resources and hence secure communication for sensor nodes became a challenging task. This paper presents a fast encryption scheme for secure communication in wireless sensor networks. The proposed scheme consists of three phases namely registration, network deployment, and data transmission. In this work, a Gaussian transposition cipher for the generation of strong key. This cipher uses Gaussian noise, modified rail fence cipher and transposition. Fast encryption has achieved using XOR-based encryption and hence the proposed scheme incurs low computational cost. The proposed scheme resistant to various security attacks.