  It is no exaggeration to say that since the introduction of Bitcoin,
blockchains have become a disruptive technology that has shaken the world.
However, the rising popularity of the paradigm has led to a flurry of proposals
addressing variations and/or trying to solve problems stemming from the initial
specification. This added considerable complexity to the current blockchain
ecosystems, amplified by the absence of detail in many accompanying blockchain
whitepapers.
  Through this paper, we set out to explain blockchains in a simple way, taming
that complexity through the deconstruction of the blockchain into three simple,
critical components common to all known systems: membership selection,
consensus mechanism and structure. We propose an evaluation framework with
insight into system models, desired properties and analysis criteria, using the
decoupled components as criteria. We use this framework to provide clear and
intuitive overviews of the design principles behind the analyzed systems and
the properties achieved. We hope our effort will help clarifying the current
state of blockchain proposals and provide directions to the analysis of future
proposals.
