With the exorbitant growth of Internet of Things (IoTs) scale and the interconnections among such a vast realm of heterogeneous objects, it is vital to uniquely identify the IoT devices and build a robust identity management (IdM) system, thus enabling many desired security mechanisms including authentication, authorization and secure exchange. An appealing technology to overcome the shortcomings of conventional online identity models and empower the construction of a robust IoT IdM system lies in decentralized identity, also known as self-sovereign identity. The existing literature on IoT IdM systems omits several critical functionalities like legacy compatibility and consideration of the IoT device lifecycle. In this study, we tackle these issues and present \(\textsf{DIdM}\) - \(\textsf{IoT}\) , a system for realizing secure and robust decentralized identity management in the IoT setting. We elaborate on the system details and give security sketch. Experimental results demonstrate its effectiveness and efficiency.