15 research outputs found
Incentivising Privacy in Cryptocurrencies
Privacy was one of the key points mentioned in Nakamoto's Bitcoin whitepaper,
and one of the selling points of Bitcoin in its early stages. In hindsight,
however, de-anonymising Bitcoin users turned out to be more feasible than
expected. Since then, privacy focused cryptocurrencies such as Zcash and Monero
have surfaced. Both of these examples cannot be described as fully successful
in their aims, as recent research has shown. Incentives are integral to the
security of cryptocurrencies, so it is interesting to investigate whether they
could also be aligned with privacy goals. A lack of privacy often results from
low user counts, resulting in low anonymity sets. Could users be incentivised
to use the privacy preserving implementations of the systems they use? Not only
is Zcash much less used than Bitcoin (which it forked from), but most Zcash
transactions are simply transparent transactions, rather than the (at least
intended to be) privacy-preserving shielded transactions. This paper and poster
briefly discusses how incentives could be incorporated into systems like
cryptocurrencies with the aim of achieving privacy goals. We take Zcash as
example, but the ideas discussed could apply to other privacy-focused
cryptocurrencies. This work was presented as a poster at OPERANDI 2018, the
poster can be found within this short document
Tracing Transactions Across Cryptocurrency Ledgers
One of the defining features of a cryptocurrency is that its ledger,
containing all transactions that have evertaken place, is globally visible. As
one consequenceof this degree of transparency, a long line of recent re-search
has demonstrated that even in cryptocurrenciesthat are specifically designed to
improve anonymity it is often possible to track money as it changes hands,and
in some cases to de-anonymize users entirely. With the recent proliferation of
alternative cryptocurrencies, however, it becomes relevant to ask not only
whether ornot money can be traced as it moves within the ledgerof a single
cryptocurrency, but if it can in fact be tracedas it moves across ledgers. This
is especially pertinent given the rise in popularity of automated trading
platforms such as ShapeShift, which make it effortless to carry out such
cross-currency trades. In this paper, weuse data scraped from ShapeShift over a
thirteen-monthperiod and the data from eight different blockchains to explore
this question. Beyond developing new heuristics and creating new types of links
across cryptocurrency ledgers, we also identify various patterns of
cross-currency trades and of the general usage of these platforms, with the
ultimate goal of understanding whetherthey serve a criminal or a profit-driven
agenda.Comment: 14 pages, 13 tables, 6 figure
An Empirical Analysis of Anonymity in Zcash
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.Comment: 27th USENIX Security Symposium (USENIX Security '18), 15 pages, Zcas