SSRD is a secure resource discovery model for devices running in a pervasive computing environment. SSRD is based on a lightweight trust model. SSRD+ is an extension of the existing SSRD model. In SSRD+, we enhance the trust model by adding dynamic trust relationship and also specifying behavioral characteristics that determine the level of trust among devices. We also add a risk model to address challenges posed by the pervasive and ad hoc nature of the network. These models work together to make the entire discovery process lightweight and secure. In this paper we present details of the trust and risk models. We illustrate the design and implementation of SSRD+ as a whole that optimally explores resources without degrading the performance of the devices while ensuring user security and privacy.