The current UTXO-based blockchains require the validators to keep the entire ever-growing UTXO set to verify transactions, which is unsuitable for ordinary machines since they occupy a large size of RAM in the long run, resulting in network centralizations. Recently, stateless blockchain technology has been proposed which uses the accumulator to combine the large UTXO set into one short, constant-sized commitment. However, the UTXO commitments in these methods are inefficient since the UXTO set is required dynamic addition and removal of elements as transactions are processed. In this work, we propose MiniChain, which replaces the UTXO set with two append-only data structures: STXO (Spent Transaction Outputs) set and TXO (Transaction Outputs) set. Thus, a valid UTXO must belong to the TXO set, but not in STXO set. Then, we construct a novel STXO commitment and TXO commitment by using a trapdoor-less RSA accumulator and a Merkle Mountain Range (MMR) respectively, greatly increasing the efficiency of accumulator. Besides, we introduce a cache mechanism, by storing the STXOs of latest $N$ blocks, the transaction proof can be kept alive for a period of time, avoiding constantly recomputing proofs for unaccepted transactions. Our evaluation shows that (i) MiniChain only needs a fixed-size RAM and the disk usage grows very slow since only the block headers are stored; (ii) comparing to the state-of-the-art work, the performance of the accumulator update has been improved from $O\left(n^2\right)$ to $O\left(n\right)$, enabling MiniChain to support a higher TPS.

当前基于UTXO的区块链要求验证器保留整个不断增长的UTXO集以验证交易，这不适合普通机器，因为它们长期占用大量RAM，从而导致网络集中化。最近，提出了无状态区块链技术，该技术使用累加器将大型UTXO集组合为一个简短的，固定大小的承诺。但是，由于需要在处理事务时动态添加和删除元素，因此UXTO集在这些方法中的UTXO承诺效率很低。在这项工作中，我们提出了MiniChain，它用两个仅附加的数据结构代替了UTXO集：STXO（花费事务输出）集和TXO（事务输出）集。因此，有效的UTXO必须属于TXO集，但不能属于STXO集。然后，我们分别使用无陷门式RSA累加器和Merkle山脉（MMR）构造了新颖的STXO承诺和TXO承诺，大大提高了累加器的效率。此外，我们通过存储最新的STXO来引入缓存机制$ñ$区块，交易证明可以保留一段时间，避免不断为不被接受的交易重新计算证明。我们的评估表明：（i）MiniChain只需要一个固定大小的RAM，并且由于只存储块头，因此磁盘使用增长非常慢；（ii）与最新技术相比，累加器更新的性能从$Ø（{ñ}^2）$ 至 $Ø（ñ）$，从而使MiniChain支持更高的TPS。