Wireless sensor networks provide solutions to a range of monitoring problems. However, they introduce a new set of problems mainly due to small memories, weak processors, limited energy and small packet size. Thus only a very few conventional protocols can readily be used in sensor networks. This paper proposes efficient protocols to distribute keys in wireless sensor networks. This is achieved without the necessity of using traditional encryption. The proposed solution replicates the authentication server such that a group of malicious and colluding servers cannot compromise security or disrupt service. We show that the proposed multiple server authentication protocols will only have O(n) complexity, where n is the number of authentication servers. The protocols use information from the sensor nodes and the servers to generate a new key, and do not solely rely on the sensor nodes to generate good random numbers. The scheme works well even when the base stations are untrusted. The proposed protocols guarantee that the new key is fresh and that the communicating nodes use the same key.