This paper, written by Patrick McCorry, Ethan Heilman and Andrew Miller and looks at cryptocurrencies Bitcoin and Ethereum, although it focuses mainly on Bitcoins, and whether the coins could be swapped in the event that two blockchains emerge from a single ‘pre-fork’ blockchain. They looked in detail at the survey and history of previous softforks and hardforks in both Ethereum and Bitcoins.
They looked at the history of forks in detail, and found that Bitcoins has implemented over six softforks, which is stored in the scriptsig of the transaction, and has experienced two accidental splits, that required minor intervention to fix. The Ethereum has executed four hardforks, in a response to community demand and to reduce the impact of network spam attacks. Most notably, TheDAO fork, which reversed a theft of approximately $40million.
The replay protection was studied in detail, which permits users to decide which blockchain can accept their newly signed transactions – something that Ethereum’s had lacked.
They went on to study Bitcoins hardfork atomic cross-chain trade, and had two parties deposit coins into a single transaction, before one party was left responsible for triggering the trade. They did the same for Ethereum, and had the same two parties deposit their coins into a smart contract.
They concluded their extensive and in-depth research, by proposing that two parties can commit to swap ‘pre-fork’ coins before a hardfork activates, before enforcing the swap after the hardfork has occurred.