# A Survey of Blockchain Security Issues and Challenges ###### tags: `Security`, `*`, `2017`, `Fork problem`, `TT` ## Summary This paper makes a summary of what is a blockchain(decentralizes, transparent, open source, autonomy, immutable, anonymity), gives examples of it’s applications and explains briefly the security issues and challenges. They talk about majority attacks, their possible causes, fork problems: Hard fork(old node verification requirement is much stricter than new node) and Soft Fork(new node verification requirement is much stricter than old node), Scaling and time confirmation. ## Comments This paper is really general, it contains information that we already know or don’t detail them. It’s a good summary but not that interesting to read since they are not criticizing or proposing an application. ## Origin Asia University and National Chung Hsing University in Taiwan. Paper is published in International Journal of Network Security in 2017.