A Fair Endorser Selection Mechanism Using Ciphertext-Policy Attribute-Based Encryption in Hyperledger Fabric

Hyperledger Fabric has gained immense attention recently being an open-source permissioned blockchain plat-form. It follows the execute-order-validate transaction flow in a network which includes the functionality of endorsement. Endorsing peers are selected based on the endorsement policy to maintain the integrity of the information on the ledger when executing a transaction. An endorser mentions its identity along with the signature to the result for validation. However, revealing the endorser identities for certain sensitive transactions may cause a conflict of interest among the consortium and may also lead to collusion among dishonest peers. Therefore, it is not only necessary that the endorsers should be selected dynamically but the transaction proposal request must also be kept confidential. In this paper, we offer a remedy based on the ciphertext policy Attribute-based Encryption (ABE) mechanism which allows a transaction proposer to encrypt the message based on policy. This determines that only the authorized peers with rightful attributes can access and perform the endorsement. In addition, to achieve ledger privacy, only the outcome of the endorsement along with the hashed message will be stored in the global ledger. This is beneficial for healthcare applications with reliable data sharing and access control, where healthcare blockchain member nodes can hold ownership of the sensitive data/records.