Ciphertext Policy-Attribute Based Encryption for Fine-grained Access Control in Blockchain

Blockchain technology has become increasingly popular in recent years to implement a wide range of services, including trade finance, supply chain management, cloud computing, cryptocurrency, and IoT (Internet of Things). Blockchain technology is classified into two types: permissioned blockchain and permissionless blockchain. In the permissionless blockchain, there is no central authority, whereas in the permissioned blockchain, a single organization has authority over the network. However, permissioned blockchain platforms such as hyperledger fabric (HLF) face challenges such as private data leakage, compromised endorsers, and fine-grained data access control. This paper proposes ciphertext-policy attribute-based encryption (CP-ABE) based access control for blockchain. The proposed scheme uses a more efficient and expressive cryptographic approach that does not rely on pairings, but instead uses elliptic curve cryptography (ECC) and a linear secret sharing scheme (LSSS) with a more flexible access structure. The selection of endorsers for the hyperledger fabric has been made by the CP ABE policies defined, thus keeping endorser’s identities a secret. The proposed scheme ensures data confidentiality and lowers overhead compared to existing schemes.