Space-Efficient Storage Structure of Blockchain Transactions Supporting Secure Verification

Abstract

The rapid growth of the blockchain size is a major bottleneck hindering its implementations in data-heavy applications. Current efforts improve the distributed storage ways and transactions' storage mechanisms of blockchain, however, the blockchain distribution and integrity are destroyed. Simplified Payment Verification (SPV) is closely related to blockchain storage, but the current solutions did not explore the privacy-preserving SPV. In this paper, we propose a new storage structure for blockchain transactions, called Coloring Index (CI), to reduce the blockchain's space occupation. Specifically, we devise an index building algorithm to simply calculate the indices of transactions for the sake of information concealing. By improving the Coloring Embedder for multi-sets query, we can store the indices into the Coloring Embedder to achieve the structured storage of transactions with small space occupation. Using CI, SPV query proceeds without revealing the user's address, thereby achieving secure data sharing in applications such as the intelligent vehicles' communications and distributed IoT. We prove CI's security against malicious full nodes when establishing possible connections between the address and the user. The experiments show that blockchain systems using our CI store one time more transactions than Merkle tree and half more than Bloom filter.