# The Evolution and Optimization Strategies of a PBFT Consensus Algorithm for Consortium Blockchains
## 2 Introduction to Blockchain  
### Blockchain Technology  
As a decentralized distributed information management architecture [9], blockchain technology is fundamentally characterized by its ability to establish a trustworthy value transfer network through cryptographic principles and consensus mechanisms. A blockchain system adopts a chain-structured data model, integrates transaction records to form data blocks chronologically, and achieves irreversible linking between blocks with the help of hash pointers, ultimately constructing a distributed ledger system with a full historical traceability [10]. Its decentralized characteristics are rooted in the P2P network architecture, which ensures that each node participates in the collaboration process in a peer-to-peer capacity. At the security level, asymmetric encryption algorithms provide underlying protection for information transmission, and digital signature technology verifies the real identity of the transaction subject. Different from the traditional trust model relying on centralized institutions, blockchain reconstructs the trust paradigm through cryptographic principles and consensus mechanisms: network nodes collaborate to verify the legitimacy of transactions based on the predefined protocols, which not only eliminates the risk of double spending, but also significantly reduces the possibility of data tampering. At this stage, the evolution of blockchain technology presents multidimensional breakthroughs: the optimization of the consensus layer: a new type of fault-tolerant algorithm significantly improves the verification efficiency; the upgrading of the contract function: Turing-complete smart contracts support the deployment of complex business logic; and the enhancement of cross-chain synergy: the atomic exchange protocol promotes the flow of value between heterogeneous chains [11]. These technological iterations are driving the accelerated penetration of blockchain applications from cryptocurrency to supply chain traceability, digital identity management, intelligent IOT,and other scenarios. However, network throughput bottlenecks, arithmetic resource consumption, and privacy leakage risks are still key factors restricting large-scale landing, giving rise to the continuous exploration of innovative solutions such as slice verification and homomorphic encryption. A blockchain block is composed of two primary elements: the block header and the block body. Its cryptographic design, combined with a layered architecture, establishes the fundamental technical basis for data immutability. This structure ensures secure data storage through the following three layers:  
1. The information encapsulation layer of the block header  
As the core verification unit of blockchain, the block header employs a streamlined data structure to store six key parameters: (1)Version Number (Version): indicates the state of protocol iterations; (2) Timestamp (Timestamp): records the time of block generation; (3) Previous Block Hash (Previous Block Hash): establishes the chain linkage by referencing the preceding block; (4) Merkle Root (Merkle Root): generated through binary tree-based hash computations; (5) Nonce (Nonce): used in the proof-of-work (PoW) computation; (6) Target Hash (Target Hash): defines the current network difficulty threshold. Among these, the Merkle Root acts as a cryptographic identifier, ensuring transaction integrity. It is derived by applying a double-hash (Double Hash) computation to transaction data within the block, iteratively merging hash values layer by layer in a bottom-up manner according to the Merkle tree structure, ultimately forming a unique root hash digest. 2. The data storage layer of the block structure  
The block body organizes verified transaction records using a Merkle tree topology [12], where each leaf node corresponds to the SHA-256 hash value of a single transaction. Intermediate nodes are generated by concatenating the hash values of two lower-level nodes and then hashing the result again.