An Agreement Protocol to Handle Byzantine Failures in Authenticated Hierarchical Configuration

Abstract

Consensus algorithms that, essentially, endeavor agreement or commit on a particular transaction, are preeminent building blocks of distributed systems. It poses more severe threats, in case, the distributed network possesses some arbitrary behaving (malicious) nodes. The proposed article adds up a non-faulty agreement decision to the requesting client nodes from the coordinator replicas. The work is divided into two-phases, namely, a fault-free and fair cluster formation which employs authenticated key management scheme and secondly, an authenticated agreement among the cluster heads resulting in secure and correct outcome of a transaction. We assume a two-layer hierarchy with different clusters of replicas in one layer associated with their cluster heads on another layer. Multiple levels of encryption are incorporated by means of two keys: (1) a unique pair-wise key between the processes, and (2) a communication key that provides more authenticity and enables a secure communication among the processes. The necessary correctness proof has also been presented. The protocol is robust and exhibits better efficiency for long-lived systems.