Towards Quantum-Secured Permissioned Blockchain: Signature, Consensus, and Logic

Abstract

While Blockchain technology is universally considered as a significant technology for the near future, some of its pillars are under a threat of another thriving technology, Quantum Computing. In this paper, we propose important safeguard measures against this threat by developing a framework of a quantum-secured, permissioned blockchain called Logicontract (LC). LC adopts a digital signature scheme based on Quantum Key Distribution (QKD) mechanisms and a vote-based consensus algorithm to achieve consensus on the blockchain. The main contribution of this paper is in the development of: (1) unconditionally secure signature scheme for LC which makes it immune to the attack of quantum computers; (2) scalable consensus protocol used by LC; (3) logic-based scripting language for the creation of smart contracts on LC; (4) quantum-resistant lottery protocol which illustrates the power and usage of LC.

Multi-Party Quantum Byzantine Agreement without Entanglement

“…Since low-dimensional entanglement can be implemented by current technology, in the future, we will study whether semi-honest distributors could be replaced by low-dimensional entanglement. One potential application of our DBA protocol is in the field of quantum blockchain [ 21 , 22 , 23 ]. In the future, we plan to apply our protocol to quantum blockchain to solve particular problems such as auction, lottery and multi-party secure computation.…”

Lottery and Auction on Quantum Blockchain

“…There is a significant number of publications related to the quantum-safe blockchain immune to attacks of quantum computers [ 6 , 7 , 8 , 9 , 10 ]. One of the most prominent proposals is the Quantum-secured Blockchain (QB) [ 6 ].…”

“…The major limitation of QB is that the consensus protocol it adopts is not efficient, because it becomes exponentially data-intensive if a large number of cheating parties is present. This limitation is overcome in [ 9 ], where a new consensus protocol is proposed, with only quadratic dependence of resources on the number of miners.…”

“…While the auction protocol we propose is the first one of the kind, a lottery protocol for quantum blockchain was already mentioned in [ 9 ]. The lottery protocol presented there is, however, defined for only two parties and for that reason cannot be applied to the majority of lotteries.…”

“…The concept of quantum blockchain was presented in [ 6 , 9 , 10 ]. We are using this general framework to specify lottery and auction protocols.…”