Taking the work out of Blockchain Security

A.W. Roscoe, Wang Lei
Chieftin Lab
University College Oxford Blockchain Research Centre

The most convincing argument for proof of work in the mining of public blockchains is, at least in our view, that it makes the creation of a fake branch too difficult or impossible thanks to the follow the longest chain principle. In this paper we suggest a modification to the structure and protocol for blockchains that provides an alternate possibility for this. Specifically, we show how blockchains can develop links in the opposite direction to the standard hashes of the hash chain thanks to building in hooks that can later be used to attach further up the chain. These, together with limited use of timing, can eliminate any realistic possibility of a branch being plausible.