Temporary Power Adjusting Withholding Attack
2026-04-15 • Cryptography and Security
Cryptography and SecurityDistributed, Parallel, and Cluster ComputingInformation Theory
AI summaryⓘ
The authors study a type of cheating in cryptocurrency mining pools called block withholding attacks. They improve on a known method (PAW) by introducing Temporary PAW (T-PAW), where attackers hold back a mined block only for a limited time instead of indefinitely. This new method can earn attackers significantly more rewards, especially when the attacker is small and has limited influence. They also find that honest mining is not the best strategy against T-PAW, revealing a major weakness in current pooled mining systems. This shows that even small miners might benefit from acting against the pool rather than cooperating.
block withholding attackmining poolPower Adjusting Withholding (PAW)Temporary PAW (T-PAW)fPoWhash rateadversarial strategyBitcoin miningdifficulty adjustmentcryptocurrency security
Authors
Mustafa Doger, Sennur Ulukus
Abstract
We consider the block withholding attacks on pools, more specifically the state-of-the-art Power Adjusting Withholding (PAW) attack. We propose a generalization called Temporary PAW (T-PAW) where the adversary withholds a fPoW from pool mining at most $T$-time even when no other block is mined. We show that PAW attack corresponds to $T\to\infty$ and is not optimal. In fact, the extra reward of T-PAW compared to PAW improves by an unbounded factor as adversarial hash fraction $α$, pool size $β$ and adversarial network influence $γ$ decreases. For example, the extra reward of T-PAW is 22 times that of PAW when an adversary targets a pool with $(α,β,γ)=(0.05,0.05,0)$. We show that honest mining is sub-optimal to T-PAW even when there is no difficulty adjustment and the adversarial revenue increase is non-trivial, e.g., for most $(α,β)$ at least $1\%$ within $2$ weeks in Bitcoin even when $γ=0$ (for PAW it was at most $0.01\%$). Hence, T-PAW exposes a significant structural weakness in pooled mining-its primary participants, small miners, are not only contributors but can easily turn into potential adversaries with immediate non-trivial benefits.