Security presents a significant challenge for the implementation and the realization of IoT scenarios. Its requirements include data confidentiality, authentication, access control as well as privacy and trust among things and services. To evaluate entities trustworthiness, exchanging trust information is crucial to reach an accurate assessment. Secure sharing and storage of trust information is essential for its confidentiality, integrity and privacy. In this context, our objective is to propose a secure trust management system based on the blockchain technology so that we can take advantages of security features it provides regarding reliability, traceability and information integrity. Blockchain based trust management can provide tamper proof data, enable a more reliable trust information integrity verification, and help to enhance its privacy and availability during sharing and storage. For this purpose, we design and implement a blockchain based trust architecture to collect trust evidences, to define a trust score for each device and to securely store and share them with other devices within the network by embedding them into blockchain transactions. Results from performance evaluation demonstrate that our proposal provides security features including tamper-proof and attacks resiliency, reliability in addition to a low complexity for IoT scenarios and applications.