On Cancellation of Transactions in Bitcoin-Like Blockchains

Önder Gürcan, Alejandro Ranchal-Pedrosa, Sara Tucci Piergiovanni

Abstract: Bitcoin-like blockchains do not envisage any specific mechanism to avoid unfairness for the users. Hence, unfair situations, like impossibility of cancellation of transactions explicitly or having unconfirmed transactions, reduce the satisfaction of users dramatically, and, as a result, they may leave the system entirely. Such a consequence would impact significantly the security and the sustainability of the blockchain. Based on this observation, in this paper, we focus on explicit cancellation of transactions to improve the fairness for users. We propose a novel scheme with which it is possible to cancel a transaction, whether it is confirmed in a block or not, under certain conditions. We show that the proposed scheme is superior to the existing workarounds and is implementable for Bitcoin-like blockchains.