An outbreak of corona virus caused by a novel virus called SARS-CoV-2 occurred at the end of 2019. The unexpected outbreak and unchecked global spread of COVID19 indicate that the current global healthcare networks have limitations in addressing the crises for public safety. In this paper, we have studied to secure the COVID-19 patients ’ data. Data security and Storage Management becomes the most promising task in it, to manage it we use cloud computing. This leads to the strong evidence of unanswered questions related to the data security over the cloud data centres. The Proposed research work aims to protect the cloud data by implementing the new approach using blockchain technology. a novel secure Online/offline Decentralized Attribute Based Encryption for cloud. The proposed scheme reduces the online computation burden for data owners by completing the preprocessing computation as much as during the offline phase. The proposed scheme eliminates a major of computation overhead on user side by migrating the partial decryption computation to the cloud servers. The secure hash blocks are generated and maintained by the cloud storage devices enhance the data security on the cloud. The block chains allow the user to trace back the malicious data access and modifications.