Möbius: Trustless Tumbling for Transaction Privacy

Abstract

Cryptocurrencies allow users to securely transfer money without relying on a trusted intermediary,
\nand the transparency of their underlying ledgers also enables public verifiability. This openness,
\nhowever, comes at a cost to privacy, as even though the pseudonyms users go by are not linked to their
\nreal-world identities, all movement of money among these pseudonyms is traceable. In this paper,
\nwe present M¨obius, an Ethereum-based tumbler or mixing service. M¨obius achieves strong notions of
\nanonymity, as even malicious senders cannot identify which pseudonyms belong to the recipients to
\nwhom they sent money, and is able to resist denial-of-service attacks. It also achieves a much lower
\noff-chain communication complexity than all existing tumblers, with senders and recipients needing
\nto send only two initial messages in order to engage in an arbitrary number of transactions.