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The most commonly used BFT consensus mechanism is the Practical Byzantine Fault Tolerance (PBFT). This algorithm was proposed by Miguel Castro and Barbara Liskov in 1999. It solves the problem of low efficiency of the original Byzantine fault-tolerant algorithm. It reduces the complexity of the algorithm from the exponential level of the number of nodes to the square level of the number of nodes, making the Byzantine fault-tolerant algorithm in It becomes feasible in actual system application.
PBFT is an algorithm developed for a distributed system execution environment based on state machine copy replication. It aims to allow most honest nodes in the system to cover the behavior of malicious or invalid nodes. The number of nodes in the PBFT algorithm is fixed, and the node identity is determined in advance, and cannot be dynamically added or deleted. It can only be applied to consortium chains or private chain scenarios with a fixed number of nodes.
Problems with the PBFT algorithm:
◼ Computing efficiency depends on the number of nodes participating in the protocol, and is not suitable for blockchains with too large number of nodes
The system has poor scalability.
◼ The system nodes are fixed and cannot cope with the open environment of the public chain. It is only suitable for alliance chains or private chains.
There is a chain environment.
◼ The PBFT algorithm requires the total number of nodes n>=3f+1 (where f represents the number of malicious nodes). The number of failed nodes in the system shall not exceed 1/3 of the total network nodes, and the fault tolerance rate is relatively low.