  Blockchain is a novel technology that is rising a lot of interest in the
industrial and re- search sectors because its properties of decentralisation,
immutability and data integrity. Initially, the underlying consensus mechanism
has been designed for permissionless block- chain on trustless network model
through the proof-of-work, i.e. a mathematical challenge which requires high
computational power. This solution suffers of poor performances, hence
alternative consensus algorithms as the proof-of-stake have been proposed.
Conversely, for permissioned blockchain, where participants are known and
authenti- cated, variants of distributed consensus algorithms have been
employed. However, most of them comes out without formal expression of security
analysis and trust assumptions because the absence of an established knowledge.
Therefore the lack of adequate analysis on these algorithms hinders any
cautious evaluation of their effectiveness in a real-world setting where
systems are deployed over trustless networks, i.e. Internet ...
