Temporary Power Adjusting Withholding Attack
New 'Temporary PAW' attack yields 22x more profit than previous methods, threatening Bitcoin pool security.
Cryptography researchers Mustafa Doger and Sennur Ulukus have detailed a significant new attack vector against cryptocurrency mining pools in their paper 'Temporary Power Adjusting Withholding Attack.' The work generalizes the known Power Adjusting Withholding (PAW) attack, where a malicious miner withholds a valid proof-of-work (fPoW) from the pool to manipulate rewards. Their new T-PAW strategy introduces a time-bound parameter T, limiting how long a block is withheld, and proves this finite approach is superior to the infinite withholding of classic PAW.
The mathematical analysis reveals the attack's profitability scales dramatically as the adversarial hash power (α), pool size (β), and network influence (γ) decrease. In a key example, T-PAW generates 22 times the extra reward of a PAW attack when α=0.05 and β=0.05. Crucially, the researchers show that honest mining becomes sub-optimal compared to executing T-PAW, even without difficulty adjustments. An adversary can see a non-trivial revenue increase of at least 1% within two weeks in Bitcoin for most (α, β) pairs, a stark contrast to the negligible 0.01% maximum from PAW.
This finding exposes a fundamental structural weakness in the pooled mining ecosystem. It demonstrates that the primary participants—small miners contributing hash power—are not just contributors but can easily transform into potential adversaries with immediate, measurable financial incentives. The attack undermines the security assumptions of pooled mining by making betrayal a rationally optimal strategy for a wider range of participants than previously understood, potentially destabilizing the trust model of major mining pools.
- T-PAW attack yields up to 22x more reward than previous PAW methods under tested conditions (α=0.05, β=0.05, γ=0).
- Attack provides at least 1% increased revenue within 2 weeks for most pool configurations, making honest mining sub-optimal.
- Exposes critical vulnerability: small miners in pools have immediate financial incentive to become adversaries, threatening pool security.
Why It Matters
This vulnerability could destabilize major Bitcoin mining pools by incentivizing participants to attack, undermining network security and trust.