Information dissemination is of vital importance in today's information-centric world. However, controlling the flow of information across multiple security domains is a problem. Most of the current solutions rely on prior knowledge of the users for authorization, which does not scale well. Also, many information sources have dynamic access control policies, which are hard to satisfy under existing schemes. In this paper, we present Synergy, a general purpose information sharing framework that uses trust negotiation to implement scalable authorization in an open environment. Synergy provides an abstraction for the information sources and consumers to accommodate new trust-aware systems as well as legacy systems. We also present a practical disaster management application that uses this framework.