Blockchain Consistency Check Protocol for Improved Reliability

Blockchain is a technology that provides security features that can be used for more than just cryptocurrencies.Blockchain achieves security by saving the information of one block in the next block.Changing the information of one block will require changes to all the next block in order for that change to take effect.Which makes it unfeasible for such an attack to happen.However,the structure of how blockchain works makes the last block always vulnerable for attacks,given that its information is not saved yet in any block.This allows malicious node to change the information of the last block and generate a new block and broadcast it to the network.Given that the nodes always follow the longer chain wins rule,the malicious node will win given that it has the longest chain in the network.This paper suggests a solution to this issue by making the nodes send consistency check messages before broadcasting a block.If the nodes manage to successfully verify that the node that generated a new block hasn’t tampered with the blockchain than that block will be broadcasted.The results of the simulation show suggested protocol provided better security compared to the regular blockchain.

“异或”校验漏检率分析

“异或”校验(Block Check Character)在使用中存在错误无法检测即漏检的发生,其可靠性未得到理论层面的证明。为证明“异或”校验的可靠性,通过对“异或”校验的校验过程进行分析,得到了“异或”校验发生漏检的原理并找到了漏检出现的根本原因。采用数学分析的方法得到了影响漏检率的因素是校验位长度与所校验数据量,推导出“异或”校验的漏检率计算公式。最后将计算公式应用在北斗短报文通信这一重要实际应用中,得到了北斗短报文“异或”校验位的漏检率在0.00390~0.00391范围内,证明了“异或”校验在短报文通信应用中的可靠性。

高速无菌牛奶砖包机上下位机通讯设计

为了解决高速无菌牛奶砖包机在设计中出现的通讯问题,并考虑对操作员操作及对砖包机维护的需要,使用工控机作为上位机,采用GE90系列PLC作为下位机,上位机对PLC内部底层通讯协议SNP进行封装,使用多寄存器寻址方式,实现了在一个采样周期内完成对一台下位机的多类型寄存器的数据采集,阐述了实现高速数据采集实现原理,并结合寄存器修改方式,实现了上位机对下位机PLC输入端口的“虚拟输入”,在此基础上,编写了上位机对下位机的监视及控制程序,并建立了基于网络的远程故障诊断及维护系统。