Cuckoo's Nest: An Ultra-Lightweight DoS-Resilient Bitcoin Mempool

The memory pool (mempool) plays a key role in processing and disseminating live transactions over the Bitcoin network. However, rising transaction loads and spam attacks significantly increase the mempool memory consumption which leads to dropped transactions, processing delays, and spikes in transaction fees, and exposes the network to sophisticated attacks. We present Cuckoo's Nest, a novel lightweight mempool design which provides resilience against spam attacks and contributes to the overall health of the network. Cuckoo's Nest reimagines the transaction pool using probabilistic data structures to fingerprint and forward live transactions. We implement Cuckoo's Nest in C++ and benchmark it using a unique 90-day Bitcoin transaction dataset. Our solution processes 300 MB worth of transaction load with only 12 MB RAM consumption with 99.999% fidelity and at three times the computational efficiency of the Bitcoin Core client. Cuckoo's Nest is an effective and efficient solution for lightweight and IoT-based Bitcoin clients; it does not require a hard fork; and its key design features can be adapted to other cryptocurrencies.