Many applications of wireless sensor networks, such as homeland security and commercial applications collect and disseminate sensitive and important information. In order for these applications to operate successfully, it is necessary to maintain the privacy and security of transmitted data. What remains undefined is an agreeable and most effective way of securing the information. This paper considers current mechanisms of authentication used to achieve security. When a node of a network can be verified as being a valid member node of the network, by some security mechanism, this is known as authentication. This node may then send and receive trustworthy messages across the network, appended with a message authentication code that only other valid nodes, holding a shared secret, may access. A comparison table is presented, illustrating various properties held by these authentications protocols. This is beneficial to designers wishing to implement the most cost effective and appropriate protocol for the intended application, as the desirable characteristics, both simulation based and implementation based, are easily identifiable. © 2007 IEEE.