Security and privacy are prominent tasks in resource constrained devises in Internet of Things (IoT) and Wireless Sensor Networks (WSN). Therefore, to ensure anonymity and trust, concealing nodes' real identity trust management are mandatory. The majority of exiting IoT security solutions didn't achieve complete security needs and/or have large computation overheads. In this paper, STAC-protocol, a secure and trust anonymous communication protocol for IOT is presented. It is applied in clustered network to achieve sender, receiver and link anonymity and trusted communication. STAC-protocol is based on lightweight key agreement protocol; the Identity Based Encryption (IBE) and Pseudonym Based Encryption (PBC). A security analysis and performance evaluation are discussed to prove the protocol's enhancement.