  We describe and analyze perishing mining, a novel block-withholding mining
strategy that lures profit-driven miners away from doing useful work on the
public chain by releasing block headers from a privately maintained chain. We
then introduce the dual private chain (DPC) attack, where an adversary that
aims at double spending increases its success rate by intermittently dedicating
part of its hash power to perishing mining. We detail the DPC attack's Markov
decision process, evaluate its double spending success rate using Monte Carlo
simulations. We show that the DPC attack lowers Bitcoin's security bound in the
presence of profit-driven miners that do not wait to validate the transactions
of a block before mining on it.
