  Although Bitcoin in its original whitepaper stated that it offers anonymous
transactions, de-anonymization techniques have found otherwise. Therefore,
alternative cryptocurrencies, like Dash, Monero, and Zcash, were developed to
provide better privacy. As Edward Snowden stated, "Zcash's privacy tech makes
it the most interesting Bitcoin alternative (...) because the privacy
properties of it are truly unique". Zcash's privacy is based on peer-reviewed
cryptographic constructions, hence it is considered to provide the foundations
for the best anonymity. However, even Zcash makes some privacy concessions. It
does not protect users' privacy in the presence of a global adversary who is
able to observe the whole network, and hence correlate the parties exchanging
money, by using their network addresses. The recent empirical analysis of Zcash
shows, that users often choose naive ways while performing the protocol
operations, not realizing that it degrades their anonymity. In this talk, we
will discuss an extension of Zcash using mix networks to enhance the privacy
guarantees of users that choose to remain anonymous by tackling two major
security challenges: one at the application layer of the scheme and one at its
network layer.
