Field area networks are rapidly expanding to include a wide range of applications. Intelligent nodes on the network will be installed in a small to medium geographical area to monitor and control processes. Such nodes are generally connected to a centralized gateway used by a service provider to monitor and control various applications. The growth in popularity of ubiquitous computing requires the use of embedded network processors in everyday objects. Even though the idea of interaction between the digital devices around us could bring a great deal of convenience it also introduces great risks. Therefore such applications would not only require measurement, control and communication functionality but also a high level of security. Smart cards offer a simple, inexpensive method of incorporating a cryptographic processor into an embedded system that will allow for the implementation of security services. A field area network has resource limitations that influence security service implementation, such as low bandwidth, limited processing power, limited storage capacity and limited communication protocols. This dissertation discussed the implementation of a security policy for embedded field area networks used in distributed real-time applications, using smart card technology. The primary objective is to formulate a policy that can be implemented to secure a field area network. The secondary objective is to determine whether this policy can be implemented using mechanisms provided by smart card technology, while maintaining reasonable system performance. It states the approach taken to finding a viable solution to the problem defined above. A comprehensive literature study provides background on relevant technology and possible solutions. In a system overview the system’s boundaries and functional requirements are defined. The implementation section outlines possible solutions and describes how these can be implemented. Evaluation, verification and quantification of the performance of the proposed system are performed according to the experimental procedures described. The results obtained are documented and discussed. In the conclusion the proposed solution and the findings from the results are placed in context. Future topics of research in this field are suggested.