A Blockchain based Access Control Framework using Attribute-based Encryption

Nowadays, Access Control becomes the main challenges of many cloud services such as file sharing. In this article we propose a Blockchain based access control framework using access polynomial. Particularly, access control is implemented as a smart contract between data owner and user. Data owner encrypts the file with cipher-key and store it into the cloud storage. The cipher-key is embedded into a polynomial, namely access polynomial, which is retrievable by the end-users via user-key. The user-key is encrypted using ABE scheme and securely transmitted to end-user. Both user’s request and data owner response are registered as Blockchain transactions which provide non-reputation logs. This method simply supports user’s revocation by updating the access polynomial. The implementation results shows that our scheme has an acceptable performance over 20000 users. This scheme is decentralized and fault tolerant. Trusted Authority is responsible for issuing attributes to the users. Smart Contract is also lightweight Component and interface for sending Transactions to Blockcahin.