Merged Bitcoin: Increasing Blockchain Security by Combining Mining Resources

Christopher Blake is a professor at Great Bay University in Dongguan, China. He received his Master's in Electrical and Computer Engineering from MIT and his PhD in the same field from the University of Toronto. His research focuses on the fundamental limits of communication of information. His research spans from the classical communication problem (in which the Universe adds passive, random noise), for which classical coding strategies are effective, to the problem of communication in the presence of Byzantine adversaries (in which noise is intelligent and adversarial), for which Blockchains provide a promising solution.

Abstract: Proof of work blockchain protocols using multiple hash types are considered. It is proven that the security region of such a protocol cannot be the AND of a 51\% attack on all the hash types. Nevertheless, a protocol called Merged Bitcoin is introduced, which is the Bitcoin protocol where links between blocks can be formed using multiple different hash types. Closed form bounds on its security region in the $\Delta$-bounded delay network model are proven, and these bounds are compared to simulation results. This protocol is proven to maximize cost of attack in the linear cost-per-hash model.