In this paper, the authors show some solutions for key management in mobile ad hoc networks. The major problem in providing security services in such infrastructure, how to manage the cryptographic keys that are needed. In order to design practical and sufficient key management systems it is necessary to understand the characteristics of ad hoc networks and why traditional key management systems cannot be used. The aim of key management is to provide secure methods for handling cryptographic keying algorithm. The tasks of key management include keys for generation, distribution and maintenance. Key maintenance includes the procedures for key storage, key update, key revocation, etc.