Trail: A Blockchain Architecture for Light Nodes

TL;DR

Trail introduces a blockchain architecture enabling nodes to store minimal data while still generating and validating blocks, significantly reducing storage requirements and enhancing decentralization.

Contribution

The paper presents a novel blockchain architecture called Trail that allows nodes to operate with small storage and generate blocks without depending on consensus algorithms.

Findings

Block size is approximately 8 KB, 100 times smaller than Bitcoin.

Nodes only store blocks, not transactions or account states.

Trail improves decentralization by enabling more users to participate as validators.

Abstract

In Bitcoin and Ethereum, nodes require large storage capacity to maintain all the blockchain data, such as transactions, UTXOs, and account states. As of May 2020, the storage size of the Bitcoin blockchain has expanded to 270 GB, and it will continue to increase. This storage requirement is a major hurdle to becoming a block proposer or validator. Although many studies have attempted to reduce the storage size, in the proposed methods, a node cannot keep all blocks or cannot generate a block. We propose an architecture called Trail that allows nodes to hold all blocks in a small storage and to generate and validate blocks and transactions. Trail does not depend on a consensus algorithm or fork choice rule. In this architecture, a client who issues transactions has the data to prove its own balances and can generate a transaction containing the proof of balances. The nodes in Trail do not store transactions, UTXOs and account balances: they keep only blocks. The blocksize is approximately 8 KB, which is 100 times smaller than that of Bitcoin. Further, the block size is constant regardless of the number of accounts and the number of transactions. Compared to traditional blockchains, clients who issue transactions must store additional data. However, we show that proper data archiving can keep the account device storage size small. Trail allows more users to be block proposers and validators and improves the decentralization of the blockchain.