||Distributed sensor networks meet many different barriers that reduce their efficient applicability. One of them is requirement of assurance of the information security when it is transmitted, transformed, and stored in the electronic service. It is possible to provide an appropriate level of security applying the present-day information technology. However, the level of the protection of information applied to the whole network is often much higher than it is necessary to meet potential threats. Since the level of security strongly affects the performance of whole system, the excessive protection decreases the system's reliability and availability and, as a result, the global security of the construction. In this paper we present a model of scalable security for digital information transmission systems for the sensor network. In our model the basic element is the risk management procedure leading to an adequate protection level.