In this work, we propose a stateless blockchain called CompactChain, which compacts the entire state of the UTXO (Unspent Transaction Output) based blockchain systems into two RSA accumulators. The first accumulator is called Transaction Output (TXO) commitment which represents the TXO set. The second one is called Spent Transaction Output (STXO) commitment which represents the STXO set. In this work, we discuss three algorithms - (i) To update the TXO and STXO commitments by the miner. The miner also provides the proofs for the correctness of the updated commitments; (ii) To prove the transaction's validity by providing a membership witness in TXO commitment and non-membership witness against STXO commitment for a coin being spent by a user; (iii) To update the witness for the coin that is not yet spent; The experimental results evaluate the performance of the CompactChain in terms of time taken by a miner to update the commitments and time taken by a validator to verify the commitments and validate the transactions. We compare the performance of CompactChain with the existing state-of-art works on stateless blockchains. CompactChain shows a reduction in commitments update complexity and transaction witness size which inturn reduces the mempool size and propagation latency without compromising the system throughput (Transactions per second (TPS)).

翻译：本文提出一种名为紧凑链（CompactChain）的无状态区块链，该方案将基于UTXO（未花费交易输出）的区块链系统的完整状态压缩至两个RSA累加器中。第一个累加器称为交易输出（TXO）承诺，代表TXO集合；第二个称为已花费交易输出（STXO）承诺，代表STXO集合。本文讨论了三种算法：（i）由矿工更新TXO和STXO承诺的算法，矿工同时提供更新后承诺正确性的证明；（ii）通过提供TXO承诺中的成员资格证据及STXO承诺中用户所花费币的非成员资格证据，证明交易有效性的算法；（iii）更新尚未花费币的证据的算法。实验评估了紧凑链在矿工更新承诺所需时间及验证者验证承诺与交易所需时间方面的性能。我们将紧凑链的性能与现有最先进的无状态区块链工作进行了比较。结果表明，紧凑链有效降低了承诺更新复杂度与交易证据规模，进而缩减内存池规模与传播延迟，同时未影响系统吞吐量（每秒交易数，TPS）。