Publications

2020
Kalodner, Harry, et al.BlockSci: Design and applications of a blockchain analysis platform”. USENIX Security Symposium 2020. Web. Publisher's Version
Lee, Kevin, et al.An Empirical Study of Wireless Carrier Authentication for SIM Swaps”. Symposium on Usable Privacy and Security 2020. Web. Publisher's Version
2018
Lee, Kevin, and Andrew Miller. “Authenticated Data Structures for Privacy-Preserving Monero Light Clients”. IEEE Security & Privacy on the Blockchain (IEEE S&B) 2018. Web. Publisher's Version
Möser, Malte, et al.An Empirical Analysis of Traceability in the Monero Blockchain”. The 18th Privacy Enhancing Technologies Symposium 2018. Web. Publisher's VersionAbstract
Monero is a privacy-centric cryptocurrency that allows users to obscure their transactions by including chaff coins, called “mixins,” along with the actual coins they spend. In this paper, we empirically evaluate two weaknesses in Monero’s mixin sampling strategy. First, about 62% of transaction inputs with one or more mixins are vulnerable to “chain-reaction” analysis - that is, the real input can be deduced by elimination. Second, Monero mixins are sampled in such a way that they can be easily distinguished from the real coins by their age distribution; in short, the real input is usually the “newest” input. We estimate that this heuristic can be used to guess the real input with 80% accuracy over all transactions with 1 or more mixins. Next, we turn to the Monero ecosystem and study the importance of mining pools and the former anonymous marketplace AlphaBay on the transaction volume. We find that after removing mining pool activity, there remains a large amount of potentially privacy-sensitive transactions that are affected by these weaknesses. We propose and evaluate two countermeasures that can improve the privacy of future transactions.