This project uses block chain technology to propose a decentralized access control method for anonymous authentication and secure cloud data storage. The suggested plan improves privacy by guaranteeing that users can authenticate themselves to the cloud without disclosing who they are. Block chain integration improves system security by removing single points of failure and enabling robust, decentralized access management. The plan handles user revocation, enables fine-grained access control, and successfully thwarts replay assaults. Users have similar communication, processing, and storage overheads to centralized methods when creating, editing, and reading material that is stored on the cloud. Our method is decentralized, which sets it apart from conventional models and makes it a useful and effective way to store data securely on the cloud for applications that need a high degree of trust.