IoT routing layer protocol, RPL is subject to several attacks. Trust measurement schemes have been suggested to secure RPL. The trust measurement denotes that how the IoT devices estimate the truth of relationship with other devices and it is measured as the combination of direct and indirect trust values. The former one denotes the self-observations and the latter one denotes the recommendations provided by the neighbors. Trust measurement improves the security of RPL. However, trust management is a real challenge when deploying RPL over resource-restricted tiny devices.