Detection constraint for Harvesting Attack in Proof of Work mining pools

PoW consensus largely depends on mining that mostly happens in the pools where Pay Per Share (PPS) and Pay Per Last N Shares (PPLNS) are the most common reward schemes that are offered to the affiliated miners by pool managers. In this report, we describe detection constraint for ``pool harvesting" attack that is harmful for honest miners. In order to profit from the attack on PPLNS pool malicious manager declares that a non-existent miner A joins that pool. She then collects the portion of reward that corresponds to the mining power of the proclaimed miner A. We discuss a number of statistical tests that may be used by honest miners in PPLNS pool to detect the attack.