Byzantine Fault Tolerance (BFT)

To create blockchain technology, its founder had to solve complex puzzles that perplexed the technology world for years. One of the challenges that had to be overcome was the Byzantine Fault Tolerance problem.

What is Byzantine Fault Tolerance (BFT)?

It is a condition in computer systems where its components encounter some fault but there is inconsistent and unreliable data about the problem. It is an imminent logical problem that could result in a catastrophe if all relevant actors don’t agree on some concerted strategy. In other words, Byzantine Fault Tolerance is the ability of a computer to thwart Byzantine Faults.

Byzantine Fault (also known as Byzantine failure) is a term derived from the problem of the Byzantine Generals as shown by historical data.

To achieve Byzantine Fault Tolerance, the system must create mechanisms that stop malicious actors from causing failures. It sounds very simple in the beginning but it is quite the opposite. Achieving Byzantine Fault Tolerance is one of the most challenging tasks every face in computing. The creation of blockchain technology was also hindered by Byzantine Faults and developers had to overcome these faults while developing a code that can guarantee safe transactions in newly designed systems.

Working of Byzantine Fault Tolerance

Byzantine Fault Tolerance works by establishing an agreed set of rules that allows solving the Byzantine Fault/Failure through a complex process. These faults occur in every network and show on very crucial timings hence it is very difficult to solve them and requires a complex code. In order to achieve Byzantine Fault Tolerance, the systems must meet the following criteria.

  • Every process should start from an undetermined state without assuming the answer as ‘YES’ or ‘NO’. The network itself calculates some deterministic values that can be applied to the process/code.
  • To share the data, a reliable means of communication should be in use in every case. This should be ensured in order to share messages in secure systems.
  • At that point, the nodes compute the data and go into a decided state. In the network, every node generates its own code during its determining process.
  • In the end, they begin counting and the one with the largest number of voting wins the state.

The above-mentioned points define the basic process of fault tolerance and every point is indispensable to avoid failure.

Example of Use Case Blockchain Consensus Protocols

Every consensus protocol on blockchain like Proof-of-work (PoW) is tolerant of Byzantine Fault. Consensus protocols allow a consensus to be reached in Byzantine systems under Byzantine conditions which ultimately pave way for tolerance in a network. Satoshi Nakamoto also considered this type of tolerance while developing the first cryptocurrency in the world and made sure to use these systems in an effective way. To create software with Byzantine Fault Tolerance, he created a chain of rules and then applied the PoW consensus protocol which helped in safe transactions for Bitcoin which is an important point.  

Advantages and Disadvantages of Byzantine fault Tolerance


  • Guarantee legitimacy of data in distributed systems even in hostile scenarios.
  • Ensure the ability to provide data and its process within diverse environments and systems.
  • Ability to provide accuracy and precision in a computational network.
  • Positively affects scalability which is the main point in these systems.
  • A large number of available nodes with Byzantine tolerance increases the security of the systems and the network.


  • The creation of these systems and tolerance is difficult even with so much effort and in some cases still leads to failures.
  • Correctness of these operations depends upon a case that its distribution is increasing with every passing day.
Josh Fernandez

Josh Fernandez

Josh Fernandez is a well-known crypto journalist who has been actively covering the world of cryptocurrency and blockchain for several years.

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