Privacy and security challenges for cryptocurrency with comparative evaluation ofanonymity techniques

Bitcoin has emerged as the most successful cryptographic currency in history that records all transactions in a distributed append only public ledger called Block chain. Within few years of its quiet launch in 2009, Bitcoin grew to comprise billions of dollars of economic value. Bitcoin have received a lot of attention: some of it good and some of it bad; they have been associated with numerous scams and thefts and other vulnerabilities which lead to the execution of various threats to the normal functionality of Bitcoin. In this paper, a systematic survey has been shown that covers the security and privacy of Bitcoin along with anonymity and privacy techniques by showing comparative evaluation of anonymity techniques.