Data are now an invaluable asset; therefore, in most machine-aided human activities, it guides all organizational decisions. Attacks to data integrity are therefore of paramount importance, as essential organization decisions can be maliciously affected by manipulation of information. This problem is particularly true in cloud computing settings where information owners are unable to monitor basic information elements such as access control and physical data storage. Recently, Blockchain has appeared as an intriguing technology that offers convincing data integrity characteristics among others. In this paper, we design a blockchain-based cloud architecture, focusing the threats of data integrity. We propose a methodology in peer to peer cloud storage to verify integrity based on blockchain, making checking more transparent, open, and publicly available. In this framework, we confirm the data integrity by using merkle trees and design a smart contract for the authentication process. Furthermore, we present an elementary model of an e square icient blockchain structure for cloud computing settings. Thus, this methodology helps in enhancing the security and integrity of the cloud storage system.