Abstract 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.

The Resource Public Key Infrastructure (RPKI) is a new infrastructure that prevents some of the most devastating attacks on interdomain routing. However, the security benefits provided by the RPKI are accomplished via an architecture that empowers centralized authorities to unilaterally revoke any IP prefixes under their control. We propose mechanisms to improve the transparency of the RPKI, in order to mitigate the risk that it will be used for IP address takedowns. First, we present tools that detect and visualize changes to the RPKI that can potentially take down an IP prefix. We use our tools to identify errors and revocations in the production RPKI. Next, we propose modifications to the RPKI's architecture to (1) require any revocation of IP address space to receive consent from all impacted parties, and (2) detect when misbehaving authorities fail to obtain consent. We present a security analysis of our architecture, and estimate its overhead using data-driven analysis.

The RPKI is a new security infrastructure that relies on trusted authorities to prevent some of the most devastating attacks on interdomain routing. The threat model for the RPKI supposes that authorities are trusted and routing is under attack. Here we discuss the risks that arise when this threat model is flipped: when RPKI authorities are faulty, misconfigured, compromised, or compelled to misbehave. We show how design decisions that elegantly address the vulnerabilities in the original threat model have unexpected side effects in this flipped threat model. In particular, we show new targeted attacks that allow RPKI authorities, under certain conditions, to limit access to IP prefixes, and discuss the risk that transient RPKI faults can take IP prefixes offline. Our results suggest promising directions for future research, and have implications on the design of security architectures that are appropriate for the untrusted and error-prone Internet.