Long-term public blockchain: Resilience against Compromise of Underlying Cryptography

Blockchain technology realizes unforgeable and decentralized ledger by applying P2P network, cryptography and consensus mechanism over distributed network. Its security relies on all of these technologies. One of fundamental problem of the security of blockchain technology is compromise of underlying cryptographic algorithms. This paper shows the impact of compromise of underlying cryptography and the way to extend the validity of blockchain applying the long-term signature scheme which was standardized in ETSI. The long-term signature scheme assume the existence of centralized PKI and secure time-stamp service. In this paper, we propose a method to apply similar concept and data structure with de-centralized manner. Our scheme avoids hard-fork of original blockchain, in the case of compromise of hash function and provides smooth-fork in the case of compromise of digital signature scheme.