This document proposes a dynamic trust management scheme for unattended wireless sensor networks (UWSNs) to provide cost-aware routing. It employs a geographic hash table (GHT) to store trust data in a distributed manner without relying on a central trusted party. The network is partitioned into grids and trust values are calculated at the grid level rather than individual nodes to reduce energy consumption. Similarity measures are used to detect trust outliers between neighboring grids and identify malicious nodes. The scheme aims to improve reliability, lifetime, and cost compared to basic trust data storage and management approaches for UWSNs.