Blockchain e a Revolução do Consenso sob Demanda

Blockchain introduces a new on-demand consensus paradigm where the set of P2P network nodes confirm the order in which the transaction blocks are aggregated into the chain of blocks, providing a reliable, secure, scalable, and immutable distributed environment for the transactions' execution on the Internet. The blockchain eliminates the need for a trusted third party and digitally creates a decentralized trust entity. The disruptive character of the technology is vast and applications are emerging in several areas: finance, health, arts, government, etc., beyond computing itself. A number of challenges exist and involve security, privacy, storage, availability, performance improvement, scalability, sustainability, etc.. This chapter presents the blockchain, its main elements, properties, models, algorithms and challenges. Special emphasis will be given to distributed consensus protocols for the maintenance of the replicated state machine, as well as the use of the technology in the context of computer networks, fog computing and IoT.