  Among the now numerous alternative cryptocurrencies derived from Bitcoin,
Zcash is often touted as the one with the strongest anonymity guarantees, due
to its basis in well-regarded cryptographic research. In this paper, we examine
the extent to which anonymity is achieved in the deployed version of Zcash. We
investigate all facets of anonymity in Zcash's transactions, ranging from its
transparent transactions to the interactions with and within its main privacy
feature, a shielded pool that acts as the anonymity set for users wishing to
spend coins privately. We conclude that while it is possible to use Zcash in a
private way, it is also possible to shrink its anonymity set considerably by
developing simple heuristics based on identifiable patterns of usage.
