CTT: A Three-Layer Tree Consensus Mechanism for Consortium Blockchains With Enhanced Security and Reduced Communication Cost

Practical Byzantine Fault Tolerance-based consensus mechanisms in consortium blockchains face challenges in scalability and communication efficiency. While recent approaches like HotStuff and Kauri have attempted to address these issues through star and tree communication structures, they still encounter limitations in security, communication costs, and node workload distribution. This article presents CTT, a novel consensus mechanism with a three-layer tree communication structure for consortium blockchains. CTT incorporates three key innovations: 1) A fixed three-layer architecture that reduces communication complexity between any two nodes to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</i>(1), compared to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</i>(log<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i>) in existing tree-based approaches; 2) specialized role distribution among nodes at different layers to optimize workload and enhance system security; 3) an improved Borda counting method for efficient consensus node selection based on multiple attributes including verification rate, propagation rate, and storage space. The mechanism features dual middle-node communication paths with bottom nodes, providing enhanced fault tolerance and security compared to existing approaches. Experimental results demonstrate CTT's effectiveness in improving scalability and security while reducing communication overhead in consortium blockchain systems. The findings have the potential to significantly advance the performance and applicability of consortium blockchains in critical areas such as finance, supply chain, and healthcare.