Byzantine bug tolerance mechanisms use components that repeat an incoming message (or only their signature) for other recipients of that incoming message. All these mechanisms assume that the act of repeating a message blocks the spread of Byzantine symptoms. For systems with a high degree of safety or security, it is demonstrated that these assumptions apply to an acceptable level of error coverage. When establishing evidence through testing, one of the difficulties is to create a sufficiently wide range of signals with Byzantine symptoms.  Such tests likely require specific error injectors.   Some spacecraft flight systems, such as SpaceX`s Dragon, take into account Byzantine error tolerance in their design. It can also be relaxed into a more «realistic» problem, where faulty components do not cooperate to induce others to make mistakes. Practical algorithms have been developed in this environment. Satoshi Nakamoto created bitcoin in 2008, and he made the network very strong as a peer-distributed model, maintained without an intermediary. Since then, many digital currencies have been created, following the same system, where all nodes share the same information (same copy of the blockchain) and each node can communicate securely with any other node through the network, knowing that it will display the same data.
Byzantine chess is considered the most general and difficult class of errors among the modes of error. The Fail-Stop-Failure mode proves the simplest end of the spectrum. While Fail-Stop error mode simply means that the only way to fail is a node crash detected by other nodes, Byzantine errors do not imply any restrictions, meaning that the failed node can generate any data, including data that makes it appear as a functional node. Thus, Byzantine failures can confuse defect detection systems, making the margin of error more difficult. Despite the analogy, a Byzantine failure is not necessarily a safety issue with hostile human interventions: it can be purely due to electrical or software errors. To make it easier to understand the interactive problem of consistency, Lamport devised a colorful allegory in which a group of army generals formulate a plan of attack against a city. In its original version, the story focused on the generals as commanders of the Albanian army. The name was changed and eventually based on «Byzantine», at the proposal of Jack Goldberg, to ensure any insult to the future.
 This formulation of the problem, along with some additional results, was presented by the same authors in their 1982 paper «The Byzantine Generals Problem.»  An example of BFT used is Bitcoin, a peer-to-peer digital system.  The Bitcoin network is working in parallel to generate a blockchain with proof-of-work that allows the system to overcome Byzantine errors and obtain a coherent global view of the state of the system. Around 1980, several system architectures were developed to implement Byzantine error tolerance. . . .