A Decentralized Data Sharing Model using Blockchain with Fine Grained Access Control

In recent years, the use of cloud services for data sharing poses a severe threat to the security and privacy of the data being shared over a public communication channel. The owners not only lose complete ownership of the data being uploaded to the cloud but the security and privacy of the data are also at stake. The interplanetary file system, IPFS has introduced a decentralized way to store data on a large scale, thereby overcoming the issue of a single point of failure and unavailability of data at all times. For added security, the use of attribute-based encryption before uploading the data on the IPFS provides an extra layer of security and confidentiality. ABE enables data owners to encrypt their data under a list of attributes with only the user possessing those attributes can decrypt the said file. The use of ABE provides fine-grained access control on the data being shared and provides the facility for easy updations of access rights. In this paper, we analyzed various data-sharing schemes based on Ethereum and IPFS and presented a scheme incorporating ciphertext policy, attribute-based encryption, CP-ABE along with Ethereum and smart contracts for enabling data storage and data sharing in the Internet of Medical Things, IoMT. The use of partial decryption also reduces the load on the resource-constrained IoT devices of a user. To further make the framework efficient and always available, the ability to access the file using a keyword search is also added to the framework. Experimental results prove that the proposed scheme uses less storage overhead as compared to some of the existing schemes thus reducing the computation time and cost too.