基于多重异或加密的区块链混币机制

混币机制是实现区块链交易信息隐私保护的技术之一。针对现有去中心化混币机制级联加密地址传输方式存在的效率低下和安全性不足等问题，提出一种基于多重异或加密的去中心化区块链混币机制（MXShuffle）。该机制为任意两个混币参与者生成一个临时共享密钥，随机选取一个参与者作为代理节点，其余参与者通过多重异或加密依次生成密钥异或集合和地址密钥异或集合，并将加密结果混洗后发送给下一个参与者，直到代理节点接收到所有参与者的两个异或加密集合并通过异或解密逐个恢复出混币交易的输出地址。安全性分析和实验表明，MXShuffle中50名参与者的混币时间仅需8 s，相较于CoinShuffle、TTShuffle、IMShuffle等方法提升了混币效率，在确保参与者隐私安全的同时降低了恶意节点监听混币关系的可能性，减小了拒绝服务攻击的影响。

Coin mixing mechanism in blockchain based on multiple XOR encryption

Coin mixing mechanism is one of the technologies to realize the privacy protection of blockchain transaction information. In view of the issues of low efficiency and insufficient security in the existing decentralized coin mixing mechanism layered encryption address transmission methods, this paper proposed a decentralized blockchain coin mixing mechanism based on multiple XOR encryption(MXShuffle). The proposed mechanism generated a temporary shared key for any two participants and randomly selected one participant as the proxy node. The remaining participants sequentially generated a key XOR set and an address key XOR set through multiple XOR encryption, and sent the encryption result after shuffling to the next participant, until the proxy node received the two XOR encrypted sets of all participants and recovered all the output addresses of coin mixing transactions through XOR decryption. Security analysis and experiments show that the mixing time for 50 participants in MXShuffle is only 8 seconds, which improves the mixing efficiency compared to CoinShuffle, TTShuffle, IMShuffle methods. While ensuring the privacy security of participants, the proposed mechanism reduces the possibility of monitoring the mixing relationships by malicious nodes and the impact of DoS attacks.