Design and Verification of a RAFT-PBFT Hybrid Consensus Architecture for High Performance and Byzantine Fault Tolerance

We propose a hybrid consensus framework that simultaneously achieves high throughput and Byzantine fault tolerance in distributed systems. The proposed structure operates as a two‑stage pipeline: it first uses a majority‑voting RAFT protocol within each shard to obtain a rapid temporary agreement, and then relies on a compact PBFT committee of representative nodes to conduct a global final approval. Under normal conditions, this approach delivers throughput and latency comparable to standalone RAFT, while in the presence of malicious nodes the PBFT stage enforces transaction integrity. Formal verification using Z3/PySMT confirms that both safety and liveness properties are satisfied. Our study introduces a new consensus paradigm that unifies the efficiency of RAFT with the security of PBFT, demonstrating its practicality for permissioned blockchains, financial platforms, and distributed databases where both performance and fault tolerance are critical.