A mobile ad hoc network (MANET) is a self-organized, multi-hop wireless communication network formed by a set of mobile nodes without relying on an established infrastructure. Self-organized public key authentication in a MANET provides security in an otherwise hostile environment by requiring participating mobile nodes to cooperate in the establishment and continued organization of an ad hoc network. However, limitations of hardware resources such as processing power, battery, storage and bandwidth, tend to make the nodes selfish and uncooperative and thus can compromise the security infrastructure of the network. In this paper, we studied the effects of selfish nodes nodes in a MANET. Specifically, we utilized concepts of Value-Based Utility (VBU) and designed a Java module for WiFi networks for measuring selfishness and giving incentives to non-selfish nodes. In an incentive-based scheme, a node can only avail of other resources or services, if the node is deemed cooperative by the other node. Examples of resources or services in this context are: forwarding of certificates, answering certificate updates, and authenticating other nodes. This framework was modeled using a Java-based Scalable Wireless Ad hoc Network Simulator (SWANS). Our results indicate that the introduction of VBU enabled each node to track the behavior of other nodes and thus react appropriately to non-cooperating nodes.