When network participants do not know how to trust each other, network operations suffer. Participants that naïvely trust will be victimized and their resources misused. Mistrustful participants will ignore opportunities and their resources will be wasted through inefficiencies. Current research on the establishment of trust often focuses on narrow models and specific domains. There is a gap between point solutions and a system-wide trust infrastructure. This research addresses the major issues in designing such a trust infrastructure. In particular, what are the threat models for a trust infrastructure? How should those threats be mitigated? What is the meaning of trust, its properties, and measurement? Where and how should trusts in applications and across networks be managed?