Research Article An Efficient Blockchain Based Data Access with Modified Hierarchical Attribute Access Structure with CP-ABE Using ECC Scheme for Patient Health Record F. Sammy 1 and S. Maria Celestin Vigila 2 1 Department of Information Technology, Dambi Dollo University, Dembi Dolo, Welega, Ethiopia 2 Department of Information Technology, Noorul Islam Centre for Higher Education, Kumaracoil, Tamil Nadu, India Correspondence should be addressed to F. Sammy; sammy@dadu.edu.et Received 21 January 2022; Revised 2 February 2022; Accepted 12 February 2022; Published 8 March 2022 Academic Editor: G. ippa Reddy Copyright © 2022 F. Sammy and S. Maria Celestin Vigila. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Secure patient health record (PHR) information exchange via cloud computing is a considerable security risk to user privacy. e fundamental reason of this issue is cloud computing’s reliance on trustworthy third parties to share data across it. To exchange data securely, many conventional cryptographic algorithms employ various keying approaches. However, relying on a trusted third party compromises the privacy of consumers’ data. To offer secure communication without the involvement of a third party, a distributed blockchain based (DBC) ciphertext–policy attribute-based encryption (CP-ABE) approach is employed in this study. Because of bilinear paring and simple scalar multiplication factors, the proposed CP-ABE system is entirely dependent on elliptic curve cryptography to reduce complexity. Furthermore, the data requester provides dynamic attributes, and a user-centric access policy is created, allowing multiple authorities to manage the attributes and provide data access. Data confidentiality, data authentication, user authentication, and tamper-proof data are all guaranteed by the suggested method. e DBC-CP-ABE method is used to provide user-centric access policies and effective key management. 1. Introduction e Internet of ings (IoT) is a new technology that allows items to communicate with one another across wireless networks. IoT devices are resource-constrained and have challenges with data processing, data storage, and energy consumption. Cloud computing provides a centralized so- lution to these resource restricted procedures to overcome these limits. e collected data is stored and processed in the cloud, but the cloud can be a trustless environment with major security issues such as single point failure, data tampering, lack of user privacy due to a lack of data access control, Denial of Service (DoS), Man-in-the-Middle attack (MiTM), and password phishing. As a result of permitted data/device access, the cloud environment is prone to se- curity breaches, compromising users’ privacy. Many public key secret writing techniques provide a fine-grained access control strategy while also protecting the privacy of users. Among other public key encryption methods, CP-ABE scheme offers one-to-many access control which allows data to be shared across multiple users. But the implementation overhead incurs due to operations with bilinear pairing. It consumes more resources with high computational cost. To overcome this issue, less complex and less resource con- sumption scalar computation with elliptic curve cryptog- raphy (ECC) is used in this work. is reduces the computational requirement by two-three times that of bi- linear pairing. is work focuses on building a security system with blockchain where hierarchical access control policy is achieved by combining CP-ABE and ECC. e experiment analysis shows that our scheme outperforms the compared work in cryptographic operations. e major focus of this work is concentrated to achieve the following criteria: Hindawi Security and Communication Networks Volume 2022, Article ID 8685273, 11 pages https://doi.org/10.1155/2022/8685273