Denial of service: Artificial difficulty increases

We learn that proof of work difficulty values are designed to ensure a desired rate of block creation in the network. These difficulty values are updated at regular intervals, usually every two weeks in the case of Bitcoin. The purpose of these updates is to account for changes in the network's computational power and maintain the target block creation rate.

However, if an attacker with a large amount of resources on the blockchain network suddenly reduces their resources, it can lead to a denial of service attack. This attack occurs when the reduced resources result in a significant decrease in block creation rate, causing a decrease in the number of transactions that can be processed. This degraded service persists until the next difficulty update.

These attacks specifically target the proof of work consensus algorithm and can have a cascading effect, potentially driving away other miners and further slowing down the network. It is important to note that any proposed solution to fix the 51% attack in proof of work would require some level of centralization, which goes against the decentralized nature of blockchain.