Consensus Algorithm | Is the Blockchain Really Secure?

6 min readOct 30, 2020

As a decentralized distributed public database, the blockchain does not have a central management agency for management, but is jointly maintained by distributed nodes using cryptographic protocols. Each node must ensure the consistency of the ledger through the underlying consensus protocol when maintaining the entire system.

Humans are inherently complex, and so are our behaviors. Therefore, it is a very challenging task to create a consensus protocol for multi-person interaction. There are many types of consensus protocols, but none of them can perfectly solve the security problems of the blockchain, and they all have their limitations. For distributed systems, the types of errors and mathematics that different consensus models can tolerate in different environments are also different. Therefore, we can derive the definition of the security of the blockchain from the judgment standard of the distributed system consensus.

Consensus algorithm——Introduction to consensus algorithm model

01 Synchronization model

As the name implies, the synchronization model requires that the sender and receiver directly resemble a face-to-face response. That is, the delay time interval is determined, and the execution time of the algorithm is also determined. However, the synchronization model does not exist in the real world, and the delay is certain in a distributed system, so the delay time is uncertain. So this model is just a hypothesis. If this hypothesis is applied to reality, then the correctness of our further research based on this model will not be guaranteed.
From another perspective, if there is still no algorithm to solve a problem under the assumption of the synchronous model, then under the asynchronous model, the predictable time is lost, and this problem is even more unsolvable.

02 Asynchronous model

In the asynchronous model, the delay time interval of the message is not determined, it can be any long time. In the asynchronous model, the program may enter a blocking state due to message waiting until a certain statement is executed, so its execution time is very uncertain. Therefore, using this algorithm also has certain drawbacks. For example, we…




The World's 1st Smart Contract based AI Conversation as Service Platform.