区块链的安全检测模型

区块链^1]是去中心化交易平台比特币的底层技术.该系统由分布式数据存储、点对点传输、共识机制、加密算法等计算机技术组成，它的安全性受到广泛关注.目前的研究大多使用数学证明的方法分析每个攻击的作用，本文提出了一种新颖的根据区块链的结构来评估和检测安全性的方法.在真实环境下当一个区块连接超过6个区块后，该区块的内容基本无法改变，被认为是稳定状态，分支产生的概率逐渐降低，因此整个系统的状态是无限循环的.该方法通过分析每个结构到达稳定状态的概率来评估系统的安全性，并通过实验分析了攻击力度，攻击状态和实验循环次数之间的关系，验证了该方法的可行性和有效性.

Security Detection Model of Blockchain

Blockchain is the basic technology of bitcoin, which is a decentralized peer-to-peer transaction system. Blockchain consists of distributed storage, peer-to-peer transfer, consensus mechanism and encryption algorithm. The security of blockchain is always the focus of people''s attention. Many researches use mathematic methods to analyze the impact of each attack in blockchain. But types of attacks in blockchain have not been fully identified. Evaluating the security of blockchain by analyzing the impact of each attack separately is incomplete. In this paper, we propose a method to detect and evaluate the security of each state in blockchain by simulating blockchain''s process. This simulation method uses two strategies: attacking algorithm and honest algorithm to get all states of blockchain including attacking states. When a block contains illusory transactions connects with more than six blocks, this state of blockchain is regarded as attacking state and others are called honest state. According to simulating process, we can analyze the probability that honest state becomes attacking state. When the probability exceeds a high value, people will get a warning, they can wait a longer time to accept the transactions in order to defend being attacked and improve the security of blockchain. Some experiments are also carried to measure this method and we use various forms to analyze and show these results, which verify our method is correct and feasible.