  Bitcoin and many other similar Cryptocurrencies have been in existence for
over a decade, prominently focusing on decentralized, pseudo-anonymous
ledger-based transactions. Many protocol improvements and changes have resulted
in new variants of Cryptocurrencies that are known for their peculiar
characteristics. For instance, Storjcoin is a Proof-of-Storage-based
Cryptocurrency that incentivizes its peers based on the amount of storage owned
by them. Cryptocurrencies like Monero strive for user privacy by using
privacy-centric cryptographic algorithms. While Cryptocurrencies strive to
maintain peer transparency by making the transactions and the entire ledger
public, user privacy is compromised at times. Monero and many other
privacy-centric Cryptocurrencies have significantly improved from the original
Bitcoin protocol after several problems were found in the protocol. Most of
these deficiencies were related to the privacy of users. Even though Bitcoin
claims to have pseudo-anonymous user identities, many attacks have managed to
successfully de-anonymize users. In this paper, we present some well-known
attacks and analysis techniques that have compromised the privacy of Bitcoin
and many other similar Cryptocurrencies. We also analyze and study different
privacy-preserving algorithms and the problems these algorithms manage to
solve. Lastly, we touch upon the ethics, impact, legality, and acceptance of
imposing these privacy algorithms.
