Paper 2021/1606

An Enhanced Long-term Blockchain Scheme Against Compromise of Cryptography

Long Meng and Liqun Chen

Abstract

Blockchain is a decentralized ledger applying the peer-to-peer (P2P) network, cryptography and consensus mechanism over distributed network. Especially, the underlying cryptographic algorithms protect the blockchain integrity and data authenticity. However, it is well-known that every single algorithm is associated with a limited lifespan due to the increasing computational power of attackers. The compromise of algorithms directly leads to the compromise of blockchain validity. There are two existing long-term blockchain schemes dealing with this problem, but we observe that in these schemes: 1) the calculation of block hash values is not compatible with existing blockchains; 2) the hash transition procedure is only specified from the first algorithm to the second one, there are multiple possibilities to implement the scheme for a longer time, some of them may lead to the failure of the scheme; 3) the security of their schemes are not formally analyzed and proved. In this paper, we propose an enhanced long-term blockchain scheme as a solution to issue 1 and 2, and we formally prove that our scheme is secure without the limitation of cryptographic algorithms. Besides, we implement our scheme, the results show that our hash transition procedure can be completed between 20 minutes (best case) and several hours (worst case) for a current Bitcoin and Ethereum blockchain, which is very efficient.