An Optimized Concurrent Proof of Authority Consensus Protocol.

Security and reliability in Blockchain software systems is a major challenge in Blockchain Oriented Software Engineering. One of the most critical components to address at the architectural level is the consensus protocol, as it serves as the mechanism for accepting valid transactions and incorporating them into the ledger history. Given that this process is executed by specific blockchain nodes, it is crucial to consider them as a key point of focus for ensuring the integrity of the entire blockchain history. This paper addresses the major challenge of security and reliability in Blockchain software systems by proposing a new protocol for Permissioned Concurrent Proof of Authority (CPoA). This protocol involves selecting a group of nodes as authority nodes, responsible for validating new identities, blocks, and transactions. The protocol is integrated with a framework that subjects validators to a unique eligibility criterion and a combination of reputation, security score, online aging, and general performance indicators related to node reliability, significantly reducing the risk of validator misbehavior and enhancing security, reliability and confidentiality of the entire blockchain compared to other existing approaches.