A key constraint that limits the implementation of blockchain in Internet of Things (IoT) is its large storage requirement resulting from the fact that each blockchain node has to store the entire blockchain. This increases the burden on blockchain nodes, and increases the communication overhead for new nodes joining the network since they have to copy the entire blockchain. In order to reduce storage requirements without compromising on system security and integrity, coded blockchains, based on error correcting codes with fixed rates and lengths, have been recently proposed. This approach, however, does not fit well with dynamic IoT networks in which nodes actively leave and join. In such dynamic blockchains, the existing coded blockchain approaches lead to high communication overheads for new joining nodes and may have high decoding failure probability. This paper proposes a rateless coded blockchain with coding parameters adjusted to network conditions. Our goals are to minimize both the storage requirement at each blockchain node and the communication overhead for each new joining node, subject to a target decoding failure probability. We evaluate the proposed scheme in the context of real-world Bitcoin blockchain and show that both storage and communication overhead are reduced by 99.6\% with a maximum $10^{-12}$ decoding failure probability.

翻译：限制区块链在物联网（IoT）中实施的一个关键瓶颈是其巨大的存储需求，这源于每个区块链节点必须存储完整的区块链。这增加了节点的负担，并导致新加入节点因需复制整个区块链而产生更高的通信开销。为在不降低系统安全性与完整性的前提下减少存储需求，近年来学界提出了基于固定速率与固定长度纠错编码的编码区块链方案。然而，该方法难以适应节点频繁退出与加入的动态IoT网络。在此类动态区块链中，现有编码区块链方案会导致新加入节点产生高通信开销，并可能面临高解码失败概率。本文提出一种无速率编码区块链方案，其编码参数可根据网络条件动态调整。我们的目标是在满足目标解码失败概率约束下，最小化每个区块链节点的存储需求以及每个新加入节点的通信开销。我们在真实比特币区块链场景中评估了所提方案，结果表明，在最大解码失败概率为$10^{-12}$的条件下，存储与通信开销均降低了99.6%。