Preventing DDoS Attacks on Bitcoin Memory Pool by the Dynamic Fee Threshold Mechanism

Blockchain is a well-known distributed technology which can be regarded as a decentralized database and combines the peer-to-peer architecture, cryptography and consensus mechanism. As the first and most famous application of blockchain and cryptocurrencies, Bitcoin also suffers from different kinds of attacks. Several studies have been done to analyze and solve these attacks. In this paper, we research the Distributed Denial-of-Service (DDoS) on Bitcoin’s memory pool (Mempool). We analyze the feasibility of this kind of attack based on the current mining and relay progress of Bitcoin, and propose the possible effects caused by this attack from some novel aspects of Bitcoin, including the confirmation time, market price and legitimate user. We further present the Dynamic Fee Threshold Mechanism to counter this attack. Our method uses several characteristics to distinguish the normal transactions in Bitcoin from the malicious spam transactions. We also make an analysis and experiments on the method, to demonstrate its effectiveness and accuracy of detecting the malicious transactions.