Bitcoin's (BTC) Difficulty Adjustment Algorithm (DAA) has been a source of vulnerability for incentive attacks such as selfish mining, block withholding and coin hopping strategies. In this paper, first, we rigorously study the short-term revenue change per hashpower of the adversarial and honest miners for these incentive attacks. To study the long-term effects, we introduce a new efficiency metric defined as the revenue/cost per hashpower per time for the attacker and the honest miners. Our results indicate that the short-term benefits of intermittent mining strategies are negligible compared to the original selfish mining attack, and in the long-term, selfish mining provides better efficiency. We further demonstrate that a coin hopping strategy between BTC and Bitcoin Cash (BCH) relying on BTC DAA benefits the loyal honest miners of BTC in the same way and to the same extent per unit of computational power as it does the hopper in the short-term. For the long-term, we establish a new boundary between the selfish mining and coin hopping attack, identifying the optimal efficient strategy for each parameter. For block withholding strategies, it turns out, the honest miners outside the pool profit from the attack, usually even more than the attacker both in the short-term and the long-term. Moreover, a Power Adjusting Withholding (PAW) attacker does not necessarily observe a profit lag in the short-term. In other words, even without a difficulty adjustment, a PAW attacker makes profits. It has been long thought that the profit lag of selfish mining is among the main reasons why such an attack has not been observed in practice. We show that such a barrier does not apply to PAW and relatively small pools are at an immediate threat.

翻译：比特币（BTC）的难度调整算法（DAA）一直是自私挖矿、区块截留和币种跳跃策略等激励攻击的脆弱性来源。本文首先严格研究了这些激励攻击中敌对方和诚实矿工每算力的短期收益变化。为了研究长期效应，我们引入了一个新的效率指标，定义为攻击方和诚实矿工每单位时间每算力的收益/成本。结果表明，与原始自私挖矿攻击相比，间歇性挖矿策略的短期收益微不足道，而长期来看，自私挖矿提供了更好的效率。我们进一步证明，依赖于BTC DAA在BTC与比特币现金（BCH）之间的币种跳跃策略，在短期对BTC的诚实忠诚矿工所产生的每单位算力收益，与跳跃者所得的收益在方式和程度上完全相同。长期而言，我们在自私挖矿与币种跳跃攻击之间建立了一个新边界，确定了每种参数下的最优高效策略。对于区块截留策略，结果发现矿池外的诚实矿工从该攻击中获利，通常甚至在短期和长期都超过攻击者。此外，功率调整截留（PAW）攻击者在短期不一定存在收益滞后。换言之，即使没有难度调整，PAW攻击者也能获利。长期以来人们认为自私挖矿的收益滞后是此类攻击在实践中未被观察到的主要原因之一。我们证明这种障碍并不适用于PAW，相对较小的矿池面临直接威胁。