A Study on Security and Privacy related Issues in Blockchain Based Applications

In recent years, Blockchain has become increasingly popular in secured transactions. The blockchain is considered to be highly advantageous over other similar technologies because of its unique and significant feature that allows us to attach a time stamp to its entity called, a block. The stamps are useful to identify each transaction as an independent atomic unit. Although technology has been successfully applied in some areas, still there are some threats associated with it. For example, if the data stored on the chain are not secured, it is quite possible that hackers may control the entire chain by using attacks like `majority attack'. The purpose of this paper is to highlight the possible types of blockchain security threats and the available techniques to manage them. In order to achieve this, a complete survey has been presented, taking into considerations, the current state of the research areas particularly in security and privacy aspects. Some of the novel ways of mitigating the risks of blockchains have also been discussed. This paper would hopefully help blockchain research scholars and application users.