  The Bitcoin Backbone Protocol [GKL15] is an abstraction of the bitcoin
proof-of-work consensus protocol. We use a model-checking tool (UPPAALSMC) to
examine the concrete security of proof-ofwork consensus by varying protocol
parameters and using an adversary that leverages the selfish mining strategy
introduced in [GKL15]. We provide insights into modeling proof-of-work
protocols and demonstrate tradeoffs between operating parameters. Applying this
methodology to protocol design options, we show that the uniform tie-breaking
rule from [ES18] decreases the failure rate of the chain quality property, but
increases the failure rate of the common prefix property. This tradeoff
illustrates how design decisions affect protocol properties, within a range of
concrete operating conditions, in a manner that is not evident from prior
asymptotic analysis.
