Abstract: Blockchain cross-chain interaction is a research hotspot in the field of blockchain. In order to avoid the phenomenon of "data island", scholars put forward cross-chain technologies such as hash locking, side chain/relay technology and notary mechanism. Based on improved PageRank algorithm and deposit pool, this paper introduces time factor in damping factor, and evaluates credit value from perspective of node’s trading performance on a single chain and as a notary to make an appropriate emphasis on the evaluation of new and old notary nodes, which can avoid the witch attacks and better attach great importance on credit supervision of nodes. Experimental results show that the proposed algorithm has a better evaluation effect than the traditional credit ranking methods, which not only improves the fairness of node credit evaluation, but also can effectively eliminate the number of malicious nodes.

Key words: notary mechanism, PageRank algorithm, credit ranking, blockchain, cross-chain

摘要： 区块链跨链交互是当前区块链领域的一个研究热点. 为了避免“数据孤岛”现象的出现，学者们提出了哈希锁定，侧链/中继技术以及公证人机制等跨链技术. 本文基于改进的PageRank算法与保证金池，将时间因子引入阻尼因子中，从单链以及充当公证人的交易表现两个维度对节点的信用值进行评估，使得新旧公证人节点在评估时有不同的侧重，能够避免女巫攻击以及较好地解决了节点信用监督不足的问题. 实验结果表明，这一算法相对于传统的节点信用值排序结果而言具有更好的评估效果，提高了节点信用值评估的公平性，也能够较为有效地剔除恶意节点. 

关键词: 公证人机制, PageRank算法, 信用排序, 区块链, 跨链