A secure resource discovery model for devices running in pervasive computing environments has become significant. Due to the constrained nature of these devices, the need for a model that allows discovery and sharing of resources without putting much overhead on the operation of devices is needed. The dependency on fixed powerful machines for ensuring security is not desired and also not feasible. In this paper, we present a resource discovery model that provides security whenever needed without degrading the performance of the device. We also propose a trust based service-oriented adaptive security mechanism named SSRD (Simple and secure resource discovery).