Möbius: Trustless Tumbling for Transaction Privacy

Abstract

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