A General and Robust Blockchain Storage System Based on External Storage Service

Recently, blockchain technology has emerged as an important technology for executing smart contracts and storing consensus data reliably in decentralized manner. On the other hand, it is required that each node has to maintain the consensus ledger in its local storage. Due to limited storage capacity, most blockchain platforms typically adopt the techniques of checkpointing and pruning the consensus ledger database. However, in case of sensitive data such as financial, healthcare or identity information, there may be some regulations on data maintenance. Thus, we have to keep those data until a specified time interval to meet the regulation compliance. In this paper, we propose a general and robust blockchain storage system, BSS, exploiting large-scale external storage services such as Amazon S3, which stores the entire blockchain consensus ledger from the genesis block. It is general in the sense that BSS is designed to be compatible with any blockchain platform. It is robust in the sense that BSS supports the f-tolerant write operation, which tolerates the malicious behavior of blockchain nodes and external storage service. We show that the BSS meets three security properties: safety, liveness, and external validity.