Vehicles will exchange much information in the future in order to efficiently maintain their inner model of the environment. Before they can belief received pieces of information, they must evaluate their reliability. Trust is a mechanism to estimate this reliability based on the sender. As cars often drive the same route, they meet each other again and again. They can establish friendship-like relations and thus are embedded in a social structure. A trust model depends on this social structure. For this reason, we simulate the driving pattern of a small town. Within this simulation, all cars are equipped with a trust model that continuously monitors the experiences made with others. The developed model focuses on direct experiences of the individual and not on a system-wide reputation which would depend on a central unit. It continuously evaluates the performance and reputation of other cars and includes a feedback loop to faster adapt to changes in the other's behaviour. To make a decision out of the collected data, the model uses the capacity of the binary error and erasure channel from information theory. This capacity provides a better decision criterion than the traditional expectation value. The proposed trust model is an individuallevel model; nonetheless it can be connected to a system-wide reputation mechanism.

Future vehicles will exchange much information through a wireless network in order to efficiently maintain their inner model of the environment. Before they can believe received pieces of information, they must evaluate their reliability. Trust is a mechanism to estimate this reliability based on the sender. It depends on friendship-like relations between vehicles, the social structure.Our traffic and network simulation shows that such relations indeed arise, because vehicles often drive the same route. Within this simulation, all vehicles are equipped with the proposed trust model, which continuously monitors the experiences made with others. The model focuses on these direct experiences of the individual and does not depend on a central reputation unit. It continuously evaluates the performance and reputation of other vehicles and includes a feedback loop to faster adapt to changes in the other's behaviour. Since the performance of a vehicle depends on the abilities of its sensors, like different abilities in velocity measurement or in traffic sign detection, the proposed model develops trust depending on the sender and on the type of the information.

Abstract.For ubiquitous communication self-organising adhoc networks become more and more important. We consider mobile phones as an appropriate trusted gateway for external machines with low communication needs. A message-based approach is best in such a scenario with moving mobile phones and machines. We propose a security model for access control to the communication infrastructure that is also messagebased. To meet the requirements of ubiquitous communicating machines, all algorithms on the sender's side are based on symmetric cryptography resulting in low computation needs. A sophisticated symmetric key infrastructure for message authentication provides the necessary key management. The trustworthiness of the mobile phone is achieved by using the SIM as a secure storage and computing module. This makes it possible to use the mobile phone not only as a user terminal but also as a trusted infrastructure component of the mobile network.