On the application side, we find DiceMix to be an ideal privacy-enhancing primitive for crypto-currencies such as Bitcoin. The public verifiability of their pseudonymous transactions through publicly available ledgers (or blockchains) makes these systems highly vulnerable to a variety of linkability and deanonymization attacks. DiceMix can allow pseudonymous users to make their transactions unlinkable to each other in a manner fully compatible with the existing systems. We demonstrate the efficiency of DiceMix with a proof-of-concept implementation. In our evaluation, DiceMix requires less than 8 seconds to mix 50 messages (160 bits, i.e., Bitcoin addresses), while the best protocol in the literate requires almost 3 minutes in a very similar setting. As a representative example, we use apply DiceMix to define a protocol for creating unlinkable Bitcoin transactions.
Finally, we discover a generic attack on P2P mixing protocols that exploits the implicit unfairness of a protocol with a dishonest majority to break anonymity. Our attack uses the attacker’s real-world ability to omit some communication from a honest peer to deanonymize her input message. We also discuss how this attack is resolved in our application to crypto-currencies by employing uncorrelated input messages by across different protocol runs.Category / Keywords: cryptographic protocols / anonymity, mixing, DC-nets, crypto-currencies, Bitcoin Date: received 24 Aug 2016 Contact author: tim ruffing at mmci uni-saarland de Available format(s): PDF | BibTeX Citation Version: 20160830:205548 (All versions of this report) Short URL: ia.cr/2016/824 Discussion forum: Show discussion | Start new discussion