Bobtail: Improved Blockchain Security with Low-Variance Mining

Abstract

Blockchain systems are designed to produce blocks at a constant average rate. The most popular systems currently employ a Proof of Work (PoW) algorithm as a means of creating these blocks. An unfortunate limitation of all deployed PoW blockchain systems is that the time between blocks has high variance. For example, Bitcoin produces, on average, one block every 10 minutes. However, 5% of the time, Bitcoin's inter-block time is at least 30 minutes.