What is Byzantine fault tolerance?

Byzantine Fault Tolerance (BFT) is one of the fundamental properties of creating reliable blockchain rules or protocols. But before we can understand what byzantine fault tolerance is, we need to take a step back and work out what peers, nodes, and consensus means and what military tactics have to do with it all. What are peers and nodes?

Is a decentralized permissionless system a Byzantine fault tolerant system?

A decentralized, permissionless system is said to be Byzantine fault tolerant if it has solved the Byzantine Generals’ Problem — a problem that Bitcoin finally solved in a distributed manner. As it stands, anyone can join a decentralized, permissionless system and start broadcasting information.

Can digital signatures provide Byzantine fault tolerance?

A second solution requires unforgeable message signatures. For security-critical systems, digital signatures (in modern computer systems, this may be achieved in practice using public-key cryptography) can provide Byzantine fault tolerance in the presence of an arbitrary number of traitorous generals.

How does bitcoin incorporate Byzantine fault tolerance into its network?

Bitcoin incorporates Byzantine fault tolerance into its network through the proof of work consensus protocol. The blockchain's PoW consensus algorithm mandates all the nodes on the blockchain to check the data structure, block size, block timestamp, block header hash, and the first transaction on every data.