An essential requirement for providing secure services in wireless sensor networks is the ability to establish pairwise keys among sensors. Due to resource constraints on the sensors, the key establishment scheme should not create significant overhead. To date, several key establishment schemes have been proposed. Some of these have appropriate connectivity and resistance against key exposure, but the resources needed in the sensors are substantial. Others are appropriate from the resource consumption perspective, but have weak performance. This paper proposes a key establishment protocol based on symmetric polynomials. To improve performance, the protocol uses a new model to distribute polynomial shares to the sensors. A key feature of the proposed protocol is the tradeoff between performance, security and resource consumption. Analysis shows that our solution has good performance compared to other approaches.